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MOBILIZATION OF SELECTED TRACE METALS BY
CONCENTRATED AQUEOUS SOLUTIONS: EFFECTS OF

SOLUTION COMPOSITION, REDOX CONDITIONS, AND
METAL PARTITIONING

presented by

John W. Marsh Jr.

has been accepted towards fulfillment
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M. S . degree in Geology

    

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Date April 15, 1985

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MOBILIZATION OF SELECTED TRACE METALS BY CONCENTRATED
AQUEOUS SOLUTIONS: EFFECTS OF SOLUTION COMPOSITION, REDOX
CONDITIONS, AND METAL PARTITIONING

BY

John W. Marsh Jr.

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE

Department of Geological Sciences

1985

ABSTRACT

MOBILIZATION OF SELECTED TRACE METALS BY CONCENTRATED
AQUEOUS SOLUTIONS: EFFECTS OF SOLUTION COMPOSITION, REDOX
CONDITIONS, AND METAL PARTITIONING

BY

John W. Marsh Jr.

The intent of this research is to gain insight into the
reasons for the segregation of metals in low temperature,
low pressure, strata-bound ore deposits. To attain this
goal, the selective nature of the mobilization process is
investigated.

The experimental results show that the cation
composition of the leaching solution, the ligand composition
of the leaching solution, the REDOX conditions under which
mobilization occurs, and the metal partitioning within the
shales; influence the efficiency of metal mobilization and
can cause selectivity in the mobilization process. These
results are interpreted to suggest that cation exchange and
ligand extraction reactions are, in part, responsible for
metal mobilization. These results are also interpreted to
indicate that readsorption of metals occur during
brine-shale interactions. Readsorption retards much of the
possible metal mobilization and causes metal repartitioning
within the shales. Hence, given a potential ore forming
brine of Na-Ca-Cl composition, the process of selective
mobilization may result in the formation of unique metal

enriched solutions.

To my father,

I miss you.

ACKNOWLEDGMENTS

I would like to thank all of my colleagues and
officemates. You had to put up with alot over the duration
of my stay. I wish you all good luck. I would also like to
thank Dr. James W. Trow and Dr. John T. Wilband for their
constructive input. Most of all I would like to thank Dr.
David T. Long. I would not have attempted, completed, or
understood the complexities of this research project without
his encouragement, prodding, and expertise. Thanks, Dave.

I would also like to thank Sigma Xi and the A.A.P.G. for
their support.

Last of all, I wish to thank Mom for all that she has

done for me. Thanks!

Table of Contents

List of Tables ........................................ v
List of Figures ....................................... vii
INTRODUCTION .......................................... 1
NATURE OF PROBLEM ................................ 1
DEVELOPMENT OF PROBLEM ........................... 2
GENERAL BACKGROUND ............................... 9
GOALS ............................................ 13
EXPERIMENTAL PROCEDURES ............................... l4
PROCEDURES ....................................... 16
SHALE MINERALOGY ................................. 16
TOTAL ORGANIC CARBON CONTENT ..................... 17
TOTAL METAL CONTENT .............................. 18
METAL PARTITIONING ............................... 20
Acid-reducible .............................. 21
Acid-oxidizable ............................. 22
Residual .................................... 22
METAL ANALYSIS ................................... 23
LEACHING EXPERIMENTS ............................. 24
RESULTS AND DISCUSSION ................................ 27
INITIAL SHALE CHARACTERISTICS .................... 27
NEW ALBANY SHALE ............................ 33
EUDORA SHALE ................................ 33
HEUMADER SHALE............................... 34
LEACHING EXPERIMENT RESULTS ...................... 35
SELECTIVE NATURE OF MOBILIZATION ............ 35
EFFECT OF SOLUTION COMPOSITION .............. 38
Mobilization as a Function of Cations in
Solution ............................... 42
Mobilization as a Function of Ligands in
Solution ............................... 44
RESULTS OF IONIC STRENGTH 1 LEACHES ......... 47
EFFECT OF REDOX ............................. 51
EFFECT OF METAL PARTITIONING ................ 55
REPARTITIONING OF METALS .................... 63
CONCLUSIONS ........................................... 90
APPENDICES ............................................ 94
Appendix A. Initial shale characteristics ....... 94
Appendix B. Metal mobilization data ............. 96
Appendix C. Metal repartitioning data ........... 103
Appendix D. Ratio data .......................... 109
LIST OF REFERENCES .................................... 121

Table

Table

Table

Table
Table
Table
Table
Table
Table

Table

Table
Table
Table
Table
Table
Table

Table

1.

2.

3.

4.

5.

A1.
A2.
A3.
B1.
B2.
BB.

B4.

List of Tables

Controls on the behavior of elements in exogenic

environments.

Examples of low temperature,
strata-bound ore deposits.

low pressure,

Comparison of average total metal contents
obtained by various methods.

Shale
Total
Metal
Metal
Metal

Ratio

characteristics.

metal content

of study shales.

partitioning (average distributions).

mobilization data.

mobilization data for anoxic leaches.

data for metal repartitioning.

Ratio data for metal repartitioning under

anoxic leaching conditions.

Shale mineralogy and age.

Total
Metal
Metal
Metal
Metal

Metal

metal content of shales.

partitioning
mobilization
mobilization
mobilization

mobilization

(average distributions).

from the New Albany Shale.

from the Eudora Shale.
from the Heumader Shale.

under anoxic conditions.

4

19
29
29
30
37
52
80

88

98

99

Table

Table

Table

Table
Table
Table
Table

Table

Table

Table

B5.

B6.

B7.

C1.
C2.
C3.
D1.

D2.

D3.

D4.

Metal
(11).

Metal
(II).

Metal
(11).

Metal
Metal

Metal

mobilization from the New Albany Shale

00.00....-.0...0.0000000000000CCOOOOOO.100

mobilization from the Eudora Shale

OOO...00......O...00.0.000000000000000101

mobilization from the Heumader Shale

OOOOOOOOOOOOOOOOOOOOOOOOOOOOOO00......102

partitioning in the New Albany Shale. .103
partitioning in the Eudora Shale. ....105

partitioning in the Heumader Shale. . 107

Ratio data for the New Albany Shale. ...... 109

Ratio data for anoxic leaches
(New Albany Shale). OOOOOOOOOOOOOOOOOOOOOOO 112

Ratio data for the Eudora Shale. .......... 115

Ratio data for the Heumader Shale. ........ 118

vi

Figure
Figure
Figure
Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

List of

Figures

Experimental procedures flow chart. ......

Experimental design. .....................

Total metal content. OOOOOOOOOOOOOOOOOOOOO

Metal partitioning.

Metal mobilization from the New Albany
Shale as a function of salt composition
for the 3 ionic strength solutions with 02

atmospheres. .....

Metal mobilization from the Eudora Shale
as a function of salt composition for the
3 ionic strength solutions with OZ

atmospheres. .....

Metal mobilization from the Heumader Shale
as a function of salt composition for the 3
ionic strength solutions with 02

atmospheres. .....

Metal mobilization from the New Albany Shale
as a function of salt composition for the 1

ionic strength solutions with 02 atmospheres.

Metal mobilization from the Eudora Shale as a

function of salt composition for the 1 ionic
strength solutions with 02 atmospheres. ....

Metal mobilization from the Heumader Shale
as a function of salt composition for the 1
ionic strength solutions with 02

atmospheres. ....

Percent mobilized from the New Albany shale

(02 atmosphere).

vii

15
26
31

32

39

4O

41

49

53

Figure

Figure
Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure

Figure

12

13.
14.

15.

16.

17.

18.

19.

20.

21.
22.
23.
24.
25.
26.
27.
28.
29.

30.

Relative Cu mobilization.

Relative Cu partitioning.

Percent
percent
shales.

Percent
percent
shales.

Percent
percent
shales.

Percent
percent
shales.

Percent
percent
shales.

Percent
percent
shales.

Example of metal repartitioning.

Cu
Ni
Pb
Zn
Cu
Ni
Pb
Zn

Cu

repartitioning
repartitioning
repartitioning
repartitioning
repartitioning
repartitioning
repartitioning
repartitioning

repartitioning

Percent mobilized from the New Albany shale
(N2 atmosphere).

Cu mobilized as a function of

hydromorphic Cu content of the

Zn mobilized as a function of

hydromorphic Zn content of the

Cu mobilized as a function of
reducible Cu content of the

Zn mobilized as a function of
reducible Zn content of the

Cu mobilized as a function of
oxidizable Cu content of the

Zn mobilized as a function of
oxidizable Zn content of the

in
in
in
in
in
in
in
in

in

viii

the

the

the

the

the

the

the

the

the

New Albany
New Albany
New Albany

New Albany

Eudora
Eudora
Eudora

Eudora

Heumader shale.

shale.
shale.
shale.

shale.

shale.
shale.
shale.

shale.

53
58

58

60

60

61

61

62

62
65

68
69
70
71
72
73

74

Figure
Figure
Figure

Figure

Figure

Figure

Figure

Figure

31.
32.
33.

34.

35.

36.

37.

38.

Ni repartitioning

Pb repartitioning

Zn repartitioning

Cu repartitioning
(N2 atmosphere).

Ni repartitioning
(N2 atmosphere).

Pb repartitioning
(N2 atmosphere).

Zn repartitioning
(N2 atmosphere).

in the Heumader shale. .
in the Heumader shale. .
in the Heumader shale. .

in the New Albany shale

in the New Albany shale

in the New Albany shale

in the New Albany shale

Selective Mobilization from the Eudora

Shale.

ix

76
77

78

84

85

86

87

93

INTRODUCTION

NATURE OF PROBLEM

Mobilization -- is the process by which potential ore
forming solutions obtain their metal content. Little is
known about the chemical controls on the mobilization
process. Recently, Long and Angino (1982) show how trace
metal mobilization from organic rich shales by aqueous
solutions is a function of temperature, ionic strength, and
ligand/cation composition of the leaching solution. Their
results suggest that the mobilization process may be
selective in the metals leached. Different metals were not
mobilized to the same degree from the same shale and the
same metal was not mobilized to the same degree from
different shales. They found that the relative amounts of
metal mobilized changed as a function of leaching solution
chemistry. Long and Angino interpreted their results to
suggest that brine leaching of sedimentary rocks could, in
part, account for the origin of some low temperature, low

pressure, ore forming fluids.

Long and Angino's (1982) study was not designed to
investigate the nature of the mobilization process;
however, their results do suggest that the mobilization
process is selective in the metals leached from a potential
source rock. If metal mobilization is selective, then this
process may, in part, explain the selective enrichment of
metals in low temperature, low pressure, sedimentary ore
deposits.

The chemical response of metals to mobilization, as
solution chemical parameters are changed, is poorly
understood. The purpose of this study is to define the
chemical nature of the mobilization process. The thesis of
this study is that changes in solution chemical parameters
will cause: (1) changes in the amounts of metals mobilized,
and (2) the formation of unique metal enriched solutions.
This thesis is addressed by studying the nature of the
mobilization process as a function of changes in
ligand/cation concentrations in solution, REDOX state of the
system, and metal partitioning in the solid phase. Three

chemically unique shales are studied.

DEVELOPMENT OF PROBLEM

A goal of low temperature aqueous geochemistry is to
understand the factors and processes which control the
mobility of an element in exogenic systems, i.e. their
geochemical cycles. In order to understand the factors and

processes which govern the geochemical cycles of elements,

the various controls on the geochemical behavior of a metal
must be defined.

The behavior of an element within an environment is in
response to the tendency towards chemical equilibrium
between the various processes which operate in an
environment. The processes are of two major types: (1)
processes which tend to immobilize elements or remove
elements from solution, and (2) processes which tend to
mobilize elements or keep elements in solution. Table 1
summarizes the various chemical processes which may govern

metal behavior.

Table 1. Controls on the behavior of elements in exogenic
environments.

A.

Precipitation/d1ssolution reactions.

A function of:
pH
pe or Eh
temperature
presencezof‘pomplexing/precipitating ligands
(OH, CO3, Cl, SO43 HCOB? dissolved organics)

Adsorption/desorption reactions.
A function of:
controls summarized in A
presence of adsorbing substrates
(clays, Fe-Mn oxides, silicates, carbonates,
solid organics)

Biologic assimilation/decay reactions.

A function of:
controls summarized in B
chemical, physical and metabolic nature of
biota

Mechanical deposition/erosion processes.

A function of:
controls summarized in C
physical/chemical nature of detrital solids
physical nature of environment

Differences in individual elemental characteristics,
such as size, charge, electronegativity, and structure,
cause differences in metal reactivities, which can in part,
account for variation in metal behaviors. For example, the
tendency for an element to bond covalently rather than by
electrostatic forces will influence the type of compounds it
forms and hence the solubility of its compounds. Other
factors which are summarized in Table 1, such as pH, pe, or
the presence of complexing ligands also influence the
behavior of an element. The behavior of Cr in solution is a
good example of the extent to which these factors can
influence the behavior of an element. Chromium behaves as a
cation or an anion in solution. This dual behavior arises
from the various valence states of Cr (a function of pe) and
the stability and type of complexes which Cr forms in
solution (a function of pH and the composition and
concentration of the ligands in solution). Cationic Cr
species (Cr(III)) are generally immobile in low temperature
aqueous environments due to precipitation as hydroxides and
oxides and adsorption onto solid media, whereas the anionic
Cr species (Cr(VI)) may be highly mobile (Gephart, 1982).

Elemental segregations, i.e. the concentration of some
elements relative to other elements within a geochemical
environment, result from the controls on metal behavior
listed in Table 1. Elemental segregations can be observed
on a variety of scales. The compositional differentiation

of the earth into the core, mantle, crust, hydrosphere, and

atmosphere; the variation of chemistries within the crust;
the metal partitioning within sediments; and the
mineralized zones within the lithosphere are examples of
elemental segregations (Krauskopf, 1979).

A spectacular example of elemental segregation is the
selective enrichment of metals in low temperature (less than
200°C), low pressure (less than 400 atm), strata-bound ore
deposits. The Pine Point ore deposit (NWT), the Appalachain
strata-bound Zn deposits (TENN. and PA.), the Tri-state
deposits (OK, MO, and KAN.), and the Creta Mineralization
Belt (TX and OK) exemplify the metal segregation which
occurs in these deposits. Table 2 summarizes the major
characteristics of these deposits.

The major metal chemistry and the mineralogy of these
deposits are simple. Sphalerite (ZnS) and Galena (PbS) are
the common sulfide minerals present in the Pb-Zn deposits,
while Chalcopyrite (CuFeSa), Covellite (CuS), and Chalcocite
(CuAS) are common in the Cu mineralizations. The exclusion
of most base metals and the simple mineralogy of these

deposits is quite apparent.

Table 2. Examples of low temperature, low pressure,
strata-bound ore deposits.

Deposit Host Rock Metal Content Age Reference

Pine Point,

NWT Carbonate Pb 2.4% Zn 6.0% Dev. Kyle (1981)

Appalachain Zn,

TN and PA. Carbonate Zn 3-4% Ord. Hoagland
(1971)

Tri-State,OK, MO,
KAN. Carbonate Pb and Zn 2-4% Miss. Hagni (1976)

Creta Mineralization Belt,
TX. Carbonate Cu 2.2-4.4% Per. Smith (1974)

During the formation of sedimentary ore deposits, the
ore metals must be PRECONCENTRATED into a source rock,
MOBILIZED from the source rock, TRANSPORTED to the site of
deposition, and DEPOSITED. In addition, to this four stage
process of ore formation, the ore metals must be
concentrated in a deposit while being separated from other
metals present in the source rock.

Traditionally, the segregation of metals within low
temperature ore deposits has been attributed to processes
which Operate at the site of deposition. Renfro (1974), for
example, proposed that the metal segregation and the mineral
zonation of Mississippi Valley-type ore deposits was due to
a metal's affinity for reduced sulfur. Others prOposed that
changes in the temperature, pressure, pH, Eh, or salinity of
the depositional environment could initiate precipitation,
cause metal segregation, and result in mineral zonation
(Anderson, 1975; Beales, 1975; Leach, 1977; Jackson and
Beales, 1967; White, 1968; Hoagland, 1971; Kyle, 1980;
Macqueen, 1976; Macqueen, 1979; Hagni, 1976; Giordano and
Barnes, 1981).

In these models it may be assumed that ore forming
solutions could contain many metals, and that during the
depositional stage only certain metals are deposited
resulting in metal segregation. However, metal segregation
could also result from chemical processes which occur during
the mobilization stage of ore solution formation. Two cases

can be considered, either the source rock is selectively

enriched in a metal, or the potential ore forming solution
selectively leaches metal from the source rock.

Selective metal enrichment in the source rock could
obviously produce a unique ore forming solution during
leaching. Although the importance of this case in the
generation of ore deposits needs to be investigated, this
research concentrates on the second case, selective
mobilization. Accordingly, the following question is

addressed in this study:

Can the manner (selective mobilization) in which solutions
leach (mobilize) metal from a source rock cause the
formation of unique metal enriched solutions?

In order to evaluate this question, the chemical nature
of the mobilization process must be studied, and is the
stimulus for this research. This study investigates the
effects of solution composition, oxidation - reduction
state, and metal partitioning on the nature of the
mobilization process. The results of this research are used

to speculate on reaction mechanisms responsible for

mobilization, and causes of metal segregation.

GENERAL BACKGROUND

Previous studies on the mobilization process involved
laboratory experiments during which various sediment samples
were leached with different aqueous solutions and the amount
of metal mobilized measured (Banat et al., 1974; Hathaway et

al., 1972; Hathaway and Galle, 1978; Weiss and Amstutz,

15

:8

I1

Vflu

1c

m.

1966; Ellis, 1968; Hirst, 1972; Burrows and Hulbert, 1975;
Long, 1977; Bischoff et al., 1981; and Long and Angino,
1982; Lu and Chen, 1977). The results of these earlier

studies are summarized as follows:

(1) metals are mobilized from a variety of sediments by a
variety of solutions;

(2) different metals are mobilized to different degrees;

(3) changes in the REDOX conditions appear to change the
efficiency of the mobilization process;

(4) the efficiency of metal mobilization varies with
changes in solution composition; and

(5) in general, the efficiency of the mobilization process
increases with increasing ionic strength and increasing
temperature of the leaching solution.

These studies were not designed to investigate the
causes of metal segregation, nor the potential selective
nature of the mobilization process. Rather they were
designed to determine the extent of metal mobilization from
sediments. However, these results do indicate that the
mobilization process may be selective in the metals
mobilized. In this study, selectivity in mobilization, is
defined as: (1) different metals mobilized to different
degrees from one shale, and (2) the same metal mobilized to
different degrees from different shales.

The selectivity of the mobilization process can be
attributed to the reaction mechanisms responsible for metal
mobilization; although the importance of particular

reaction mechanisms are unknown. For example, metals may be

-10-

mobilized by the complete or partial dissolution of
particular shale phases, by cation exchange reactions, or by
extraction reactions (Long, 1977; Long and Angino, 1982;

and Forstner et al., 1981). The processes responsible for
metal mobilization may influence the selectivity of the
mobilization process.

Long (1977) hypothesized that cation exchange reactions
and ligand extraction reactions are important mobilizing
mechanisms. If this hypothesis is true, then the type of
cation and ligand in the leaching solution should effect the
mobilization of metals. Leaching solutions which contain
cations with the greatest exchanging powers would be
expected to mobilize metals the most effectively. Ligand
composition would aid mobilization if stable metal-complexes
can be formed in solution. The mobilization process would
be selective because metals which form the most stable
complexes in solution and metals which are most loosely
bound to the sediment will be preferentially mobilized.

On the other hand, if metal mobilization mainly
resulted from dissolution of particular chemical shale
fractions, all metals would be leached equally and the
selectivity of the mobilization process would not
necessarily be a function of solution composition. In this
second case the apparent selectivity of the mobilization
process would be a function of the relative partitioning of

the metals within the shales.

-11-

Metals are known to be associated with a variety of
chemical phases in sediments, such as clay particles,
carbonate precipitates, Fe/Mn oxides, organic material, and
other crystalline materials (Burrows and Hulbert, 1975;
Long, 1977; Forstner, 1981; Gephart, 1982). The percentage
of each metal associated with the various sediment fractions
is known as the metal partitioning within the sediment.

The nature of metal partitioning and the existence of
several adsorbing phases within a sediment could aid in the
selectivity of the mobilization process. For example, if
the mobilization process attacked only certain shale
fractions, such as the organic material fraction, the metals
associated with the organic material would be preferentially
released. In this case, the relative order of metal
mobilization would, ideally, follow the relative order of
metal concentrations in the particular shale fraction
attacked.

Factors that determine which sediment fractions will be
susceptable to attack by aqueous solutions are speculated to
be ionic strength, temperature, REDOX conditions, and the
relative concentrations of cations and anions in the
leaching solution (Burrows and Hulbert, 1975; Forstner, et
al., 1981; Lu and Chen, 1977; Long and Angino, 1982;

Holland, 1980 personal communication).

-12-

GOALS

The relative importance of the various mobilizing
mechanisms have not been determined and the factors which
govern the selectivity of the mobilization process have not
been clearly defined. Based on the previous research five
goals are established to investigate the selective nature of

the mobilization process. They are:

(1) To confirm the selective nature of the mobilization
process.

(2) To determine how, the absolute composition of the
leaching solution, affects the selectivity of the
mobilization process;

(3) To determine how, the REDOX condtions under which
mobilization occurs, affects the selectivity of the
mobilization process;

(4) To determine how, the metal partitioning within a
shale, affects the selectivity of the mobilization process;
and

(5) To interpret from the results of this study possible
causes for the selectivity of the mobilization process.

-13-

EXPERIMENTAL PROCEDURES

The working hypothesis for this study, based on past
experimental studies, is that: the selectivity of the
mobilization process is a function of (1) absolute
composition of the leaching solution; (2) the REDOX
conditions under which mobilization occurs; and (3) the
metal partitioning within the shales. This hypothesis is
tested by studying the mobilization behavior of Cu, Fe, Ni,
Pb, and Zn from three chemically unique shales. The shales
were chemically characterized by determining their
mineralogies, percent total organic carbon contents, total
metal contents, and their initial metal partitionings. The
shales were then subjected to various leaching experiments
for which the leaching atmospheres (either N2 or OZ) and the
composition of the leaching solutions were controlled. In
addition, the metal partitioning within the shales was
determined again after brine-shale interactions. Figure 1
is a flow chart of the experimental procedures used in this
study. A detailed description of the experimental

procedures follows.

-14-

 

 

 

 

 

 

Initial shale sample * LL

preparation. Shale mineralogy. Metal partitioning.
Percent organic .

New Albany carbon. 39‘1””

Eudora ~ Idizable

Heumader Residual

 

 

 

 

 

 

 

 

i '| Total metal contend
Leaching Experiments.
50°C 72 hours —
lonic strengths 0.|.63 {rm-”9:1 Zan'igormg Gill
02 8 N2 Atmospheres eoc e 5 ae.

Salts:

Kl, KBr, KCI, NaCl,
CaClz , 8 lMgCl2

l Mobilized metals. Ir Metal analysis I

Figure 1. Experimental procedures flow chart.

 

 

 

 

 

 

 

 

 

 

 

 

-15..

PROCEDURES

All glassware were prepared by washing with soap and
water, rinsing with distilled water, and rinsing a second
time with doubly distilled water. The glassware was then
soaked in 3 percent HCl for 24 hours, rinsed with doubly
distilled water, and allowed to dry. All reagents used were
of A.C.S. grade.

The shale samples were initially washed with distilled
water and a nylon brush and allowed to dry overnight. The
shales were then broken into pieces about 0.5 to 1.0 cm in
size. The pieces were crushed in a titanium ball shatter
box for 90 seconds, sieved to less than 144 microns, and
stored in polyethylene containers. The prepared shale

samples were used in all of the remaining experiments.

SHALE MINERALOGY

The mineralogy of the bulk shale and the clay minerals
were determined by x-ray spectroscopy according to the
methods of Carroll (1970). The clay mineralogy was
determined from diffractograms prepared by treating the bulk
shale samples to remove carbonate and other soluble salts,
Fe-oxides, and organic material. Clay mounts on glass
slides were x-rayed with nickel filtered Cu K(alpha)2

radiation.

_16_

TOTAL ORGANIC CARBON CONTENT

The percent organic carbon content was determined using
the technique outlined by Gaudette et al. (1974). Between
0.2 and 0.5 grams of sample were placed into a 500 ml
Erlenmeyer flask. Ten milliliters of 1N K2Cr207 were added
and mixed gently, after which 20 ml of concentrated H2304
were added and mixed for 1 minute. Care was taken not to
splash material onto the sides of the flask. The mixture
was allowed to stand for 30 minutes and then diluted to 200
ml with distilled water. Ten milliliters of 85% H3PO4, 0.2
grams of NaF, and 15 drops of diphenylamine indicator
solution were added and the solution was back titrated with
0.5N ferrous ammonium sulfate solution to the brilliant

green end point. The equation:

% Organic carbon = [(10)(1-(T/S))][(1.0N)(0.003)(100.0/W)]

was used to calculate the percentage of organic carbon in

the sample. The variables in the equation are:

T = ml of ferrous ammonium sulfate solution for titration of
sample.

S m1 of ferrous ammonium sulfate solution for blank.

W weight of sample in grams.

1.0N = normality of K2Cr207 solution.

10 = volume of K2Cr207 solution.

0.003 = 12/4000 = meq weight of carbon.

-17-

TOTAL METAL CONTENT

The total metal contents of the shales were determined
in two different manners. The first method was a lithium
metaborate fusion technique outlined in the Perkin Elmer
Atomic Adsorption Instruction Manual (1976). A sample
weight of 0.2000 grams was placed into a graphite crucible
with 1.0 grams of LiBOB and mixed thoroughly. The mixture
was then fused in a furnace for 20 minutes at 1000°C. The
molten bead was dissolved in 5 ml of HCl and 50 ml of doubly
distilled water. After which the solution was diluted to
100 ml in a volumetric flask and stored in a precleaned
polyethylene bottle. Trials were run in triplicate with
blanks prepared using the same technique. Metal analyses
were done by atomic adsorption spectroscopy.

The second method used to obtain the total metal
contents of the shales was simply to add up the total
amounts of metals found to be present in the various shale
fractions and back calculate to determine the original metal
concentration in the shale samples. Table 3 is a comparison
table of the various techniques employed to determine the
total metal content of the shales. The total metal content
values listed under the summation "A" method were used in
this study because these values are similar to the other
values and because they are averages calculated from the

greatest sample pOpulation.

_18-

Table 3. Comparison of average total metal contents
obtained by various methods.

SHALE and METAL METHOD

New Albany Shale 1 2 3

Metal LiBO3 Fusion Summation A Summation B
4

Cu 97.4 (33.8) 96.8 (4.4) 103.8 (7.8)

Fe 48238 (3859) 44808 (1695) 46373 (3035)

Ni 143.0 (22.1) 109.9 (13.0) 104.5 (20.8)

Pb 42.6 (38.5) 15.7 (4.4) 27.8 (45.7)

Zn 1848 (536) 2740 (128) 3008 (232)

1-- The fusion technique was employed on bulk shale samples.
Values are averages calculated from 3 trials; n=3.

2-- Summation A averages the results of the leaching
experiments; n=20.

3-- Summation B averages the results of the initial metal
partitioning determinations; n=6.

4-- Values in parentheses are 95% confidence intervals based
on the range (Sokal and Rohlf, 1969).

-19-

METAL PARTITIONING

The metal partitioning within the shales was determined
using a selective chemical extraction technique, modified
after Tessier, et al. (1979) and Gephart (1982), during
which the metals are selectively leached from specific
chemical shale fractions. Three chemical fractions were
identified in the shales: metals leached with an
acid-reducing solution, metals leached with an
acid-oxidizing solution, and residual metals left in the
shale after the chemical attacks.

The chemical fractions have been suggested to represent
various sediment phases. For example, the acid-reducible
metals are associated with metals adsorbed onto clays, Fe
and Mn oxides, and carbonate precipitates. The
acid-oxidizable metals are associated with metals adsorbed
onto organic material and with sulfide precipitates. The
metals associated with the reducible and oxidizable
fractions are collectively referred to as hydromorphic
metals and are commonly considered to be "mobile".

Several assumptions are made when selective chemical
extractions are used. The assumptions are: (1) that
selective extractions completely leach metals associated
with the specified fractions, (2) that only the specified
fractions are attacked, and (3) that metal readsorption does
not occur. The assumptions and methodology of selective
chemical extractions have been investigated (Chester and

Hughes, 1967; Gibbs, 1973; Gupta and Chen, 1975; Tessier, et

-20-

al., 1979; Gephart, 1982); and metal partitioning in
sediments as determined by selective chemical extractions is
taken to be a good indicator of the state of a metal in a
sediment (Lion and Leckie, 1982).

The three identified shale fractions in which metals
can exist are referred to as acid-reducible,
acid-oxidizable, and residual in this study because
selective chemical extractions were designed for use on oxic
sediments not organic rich shales and it is not known
whether or not the metal associations commonly used in the
literature are accurate. The following is the procedure

used to identify these fractions.

Acid-reducible - Five grams of shale sample were placed into
a glass centrifuge bottle, after which 100 ml of 0.04 M
NHZOH*HC1 (25% v/v HOAc) were added. The mixture was
allowed to digest for 6 hours with occasional agitation at
96% (plus or minus 3C). The sample was centrifuged for 12
minutes at 1500 rpm and 50 m1 of supernatant were pipetted
into a polyethylene bottle for analysis (1 ml of
concentrated HCl was added before storage). The remaining
supernatant was siphoned off and discarded. The residue was
rinsed with approximately 10 ml of doubly distilled water

and then subjected to the acid oxidizing attack.

-21-

Acid-oxidizable - Fifteen milliliters of 0.02M HNO3 and 25
ml of 30% H202, pH adjusted to 2.0 with HNO3 were added to
the residue. The 30% H202 was added in 5 ml aliquots five
minutes apart underneath a hood. The mixture was allowed to
digest for 2 hours at 85C (plus or minus 2b) with occasional
agitation. After two hours a second 10 ml aliquot of 30%
H202 was added to the mixture and allowed to digest. After
one hour a third 10 ml aliquot was added. The mixture was
allowed to digest for 3 more hours with occasional
agitation, and then allowed to cool. After cooling 25 ml of
3.2M NH4OAc (20% v/v HNO3) were added. Following the
addition of the 3.2 M NH4OAc the mixture was agitated
continuously for 30 minutes and then centrifuged for 12
minutes at 1500 rpm. The supernatant was siphoned into a
100 ml volumetric flask, diluted to volume, and transferred
into a polyethylene bottle for analysis. One milliliter of

HNO3 was added to the supernatant before storage.

Residual - The residue was washed with distilled water and
dried for 4 days. After drying the residue was weighed and
a subsample taken for metal analysis using the lithium

metaborate fusion technique outlined earlier.

_22_

METAL ANALYSIS

Metal analyses were done by atomic adsorption
spectroscopy using a Perkin-Elmer Spectrophotometer, Model
560 with flame attachment. Metal analyses were done
directly for the solutions of 0 and 1 ionic strength
leaches, the acid reducing attacks, the acid oxidizing
attacks, and the lithium metaborate fusions. Standards were
prepared in the various matrices to minimize possible matrix
effects.

The 31 (ionic strength) solutions were too concentrated
with salts to analyze directly by atomic adsorption
spectroscopy. Therefore prior to analyses the metals were
extracted from the leaching solutions using the MIBK - APDC
extraction technique of Florence and Bately (1976). Fifty
milliliters of sample were pipetted into a 100 ml beaker and
5 ml of a 1% ammonium pyrrolidine dithiocarbamate (APDC)
solution were added. The pH was adjusted to approximately
2.5 with concentrated HNO3. The solution was then
transfered to a 200 m1 volumetric flask and 20 ml of methyl
isobutyl ketone (MIBK) were added. After 5 minutes of
agitation the solution was allowed to separate into two
phases. The MIBK phase was immediately analyzed for its
metal content. Standards were prepared using the same

technique and background matrices.

-23-

The metals Cu, Fe, Ni, Pb, and Zn were measured. If
metal concentrations were initially above the linear range
for atomic adsorption analyses dilutions were made with the

appropiate blank solutions.

LEACHING EXPERIMENTS

Leaches were conducted at 50°C, for 72 hours, at
solution ionic strengths of 0,1, and 3. The salts used were
KI, KBr, KCl, NaCl, CaC12, and MgC12. Experiments were run
in triplicate in either oxygen or nitrogen atmospheres.
Nitrogen atmospheres were attained by sealing nitrogen
filled centrifuge bottles inside a nitrogen atmosphere glove
box. A temperature of 50°C was used because sufficient
metals were mobilized at this temperature to study the
hypotheses and fewer problems were encountered with
evaporation loss of solution (Long, 1977). A leaching
duration of 72 hours was used following the procedures of
Long (1977). Figure 2 is a summary of the experimental
design for this research.

Leaching experiments were performed on the shales using
the "syranwrap” technique outlined by Long (1977). Five
grams of sample were placed into a glass centrifuge bottle
and 100 ml of leaching solution were added. The bottle was
then sealed by stretching a precleaned piece of syranwrap
over the neck of the centrifuge bottle and wrapping wire
around the neck. The neck of the bottle was initially

wrapped with teflon tape to insure an airtight seal. The

-24-

sample was then placed into a Fisher, model 127, constant
temperature, shaking waterbath for 72 hours. After 72 hours
of constant agitation at 50°C the suspension was centrifuged
for 12 minutes at 1500 rpm and about 75 ml of supernatant
siphoned into a prewashed polyethylene bottle for analyses.
One milliliter of HCl was added to the supernatant before
storage. The remaining supernatant was discarded. The
leached residue was rinsed with 10 ml of distilled water and
the metal partitioning within the leached shale residue

redetermined.

-25-

SALTS

KI
KBr
KCl
NaCl
CaC12
MgClZ

TEMPERATURE

50°C

IONIC STRENGTHS ATMOSPHERES

0 Oxygen
1 Nitrogen
3

MISCELLANEOUS

Trials done in triplicate.
Leaching duration 72 hours.

Figure 2. Experimental design.

-26-

RESULTS AND DISCUSSION

The results (with discussion) of this research will be
presented in two sections. The first section presents the
results of analyses which chemically characterize the
shales. The second section presents the experimental
results in terms of the individual factors hypothesized to
influence the selectivity of the mobilization process. This
work concentrates on the results of experiments using the

most concentrated solutions (ionic strength of 3).

INITIAL SHALE CHARACTERISTICS

Several considerations were taken into account in
choosing which shales would be used in this study. The
first consideration was that the shales must contain enough
metals for mobilization studies. Secondly, the shales
should be similiar to those shales which are hypothesized to
have been a possible source of metals for low temperature,
low pressure, strata-bound ore deposits. The third
consideration was that the metal partitioning within the
shales be different from one other. Therefore, eight shales
were initially sampled and characterized by chemical

properties such as clay mineralogy, percent organic carbon

-27-

content, total metal content, and metal partitioning within
the shales.

The three shales chosen for this research; the New
Albany Shale, Indiana; the Eudora Shale, Kansas; and the
Heumader Shale, Kansas are chemically unique. They have
similar mineralogies (Table 4), however the total metal
contents (Table 5; Figure 3), the metal partitioning within
the shales (Table 6; Figure 4), and the total percent

organic carbon contents (Table 5) are different.

-23-

Table 4. Shale characteristics.

*

SHALE NAME MINERALOGY AGE

New albany Shale I, Ch, K, MX, and Q Devonian
Eudora Shale I, Ch, K, and Q Pennsylvanian
Heumader Shale I, Ch, K, Q, and F Pennsylvanian

* I=Illite, Ch=Chlorite, K=Kaolinite, MX=Mixed layered
clays, Q=Quartz, F=Feldspar

Table 5. Total metal content of study shales.

*
**

METAL NEW ALBANY EUDORA HEUMADER MEAN SHALE
Cu 96.8 (4.4) 100.5 (28.4) 33.0 (5.8) 39

Fe 44808. 22493. 29757. 48000

(1695.) (1196.) (1823.)

Ni 109.9 (13.0) 294.9 (16.0) 36.0 (10.5) 68

Pb 15.7 (4.4) 183.0 (28.5) 10.5 (3.4) 23

Zn 2740. (128.0) 810. (43.0) 85.2 (7.1) 120

% Org. C 8.13 8.38 0.99

* Values are in ppm whole rock. Values in parentheses are
95% confidence intervals.
** Mean shale values obtained from Wedepohl (1968).

-29-

Table 6.

SHALE
(METAL)

(Cu)

New Albany
Eudora
Heumader

(Fe)

New Albany
Eudora
Heumader

(Ni)

New Albany
Eudora
Heumader

(Pb)

New Albany
Eudora
Heumader

(Zn)

New Albany
Eudora
Heumader

* Values are percentages of metals associated with the

various

REDUCIBLE

\IOH
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21.4
28.3
12.8

7.4
17.1
14.0

shale fractions.

OXIDIZABLE

_30_

81.3
47.2
54.7

48.9
79.6
20.5

29.8
29.9
23.2

79.3
68.3
27.5

Metal partitioning (average distributions).

RESIDUAL

17.0
52.6
37.6

31.4
61.6
76.5

29.4
14.1
40.9

48.8
41.8
64.0

13.3
14.6
58.5

 

 

 

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-32-

NEW ALBANY SHALE

Illite, kaolinite, chlorite and quartz are the primary
minerals making up the New Albany shale. Mixed layered
clays and pyrite are also present. Except for Cu and Zn,
the total metal content is close to the mean shale values of
Wedepohl (1968). Copper and zinc are enriched relative to
the mean shale values. The average percent organic carbon
content is 8.13%. The metal partitioning within the shale
is different for each metal, however in general the
oxidizable fraction has the greatest concentration of metals
associated with it. The oxidizable fraction is followed by
the residual and reducible fractions, respectively, in the

percentage of metals associated with the fractions.

EUDORA SHALE

The Eudora shale consists primarily of illite,
kaolinite, chlorite, and quartz. Pyrite is present, however
mixed layered clays are not found. The total metal contents
are highly enriched relative to the mean shale values for
all metals with the exception of Fe. The percent organic
carbon content is 8.38%. The metal partitioning within the
shale is different from the New Albany shale, with the
greatest concentration of metals associated with the

oxidizable and residual fractions.

_33_

HEUMADER SHALE

The mineralogy of the Heumader shale is primarily
illite, kaolinite, chlorite, and quartz. Feldspars are also
present. The Heumader shale is the least concentrated, with
respect to total metal content, compared to the three
shales. All metal concentrations, except for Ni, are below
those of the mean shale values. Nickel is slightly
enriched. The percent organic carbon content is 0.99%. The
metal partitioning within the shale is different from the
New Albany and the Eudora shales with the majority of the
metals being associated with the residual fraction and a
high percentage of metals associated with the reducible
fraction.

In summary, the three shales have unique metal
contents, yet are mineralogically similar with illite,
kaolinite, chlorite and quartz being the primary minerals.
The New Albany and the Eudora shales are enriched in metals
relative to the mean shale values, whereas the Heumader
shale is generally depleted. The Eudora shale has the
greatest percent organic carbon content followed by the New
Albany and Heumader shales. The metal partitioning is also
different. Metals are partitioned differently within the
shales, and the same metal is partitioned differently
between the shales. The majority of metals are associated
with the oxidizable fractions in the New Albany and Eudora
shales, and in the residual and reducible fractions in the

Heumader shale.

-34-

LEACHING EXPERIMENT RESULTS

SELECTIVE NATURE OF MOBILIZATION

The selective nature of the mobilization process is
apparent from the variation in the mobilization behavior of
Cu, Fe, Ni, Pb, and Zn from the New Albany, Eudora, and
Heumader shales. Table 7 summarizes the experimental
leaching results. Table 7 also lists the total metal
contents and the hydromorphic metal contents (the sum of the
metal contents of the acid-reducible and acid-oxidizable
fractions) of the three shales.

It is clear from the results, summarized in Table 7,
that the metals are not mobilized to the same degree from
the three shales. Different metals are mobilized to
different degrees from the same shale and the same metal is
mobilized to different degrees from different shales. For
example, during the 31 KI leaching experiment approximately
17% of the Cu, 0% of the Fe, 0.5% of the Ni, 21% of the Pb,
and 0.02% of the Zn present in the New Albany shale were
mobilized. These values differ from the amount of metals
mobilized from the Eudora and Heumader shales during the
same leaching experiment. Approximately, 13% of the Cu, 0%
of the Fe, 0.1% of the Ni, 3.8% of the Pb, and 0.01% of the
Zn present in the Eudora shale were mobilized, whereas
approximately 40% of the Cu, 0% of the Fe, 0.2% of the Ni,
12% of the Pb, and 0.1% of the Zn present in the Heumader

shale were mobilized. The variation in the amount of metal

-35-

mobilized from a sediment is commonly hypothesized to be the
result of variation in the total metal contents of a
sediment or variation in the hydromorphic metal contents of
a sediment (Forstner, et al., 1981). However, these
hypotheses are not supported by the mobilization data.

If the mobilization process is not selective and the
variation in the amount of metals mobilized from a sediment
is a function of total metal content and/or hydromorphic
metal content of the shales, then metal mobilization should
increase with increase in total metal content and/or
hydromorphic metal content of the shales. Metal
mobilization from the New Albany shale, for example, would
be expected to increase in the order of Pb < Fe < Ni < Cu <
Zn (based on hydromorphic metal content; Table 7) or Pb < Cu
< Ni < Zn < Fe (based on total metal content; Table 7).
These orders are not observed. The relative order of metal
mobilization from the New Albany shale never follows the
orders predicted from the total metal content or
hydromorphic metal content data and those orders of metal
mobilization which are observed change as solution chemistry
is changed. This is true for each of the shales. Thus, the
variation in the degree of metals mobilized from the shales

is interpreted to be the result of selective mobilization.

-35-

Table 7.

SHALE
New Albany Shale
*

Total Metal Content
Percent Hydromorphic
Percent Mobilized**

KI

KBr

KCl

NaCl

CaC12

MgC12
Eudora Shale
Total Metal Content
Percent Hydromorphic
Percent MObilized

KI

KBr

KCl

NaCl

CaC12

MgC12
Heumader Shale
Total Metal Content
Percent Hydromorphic
Percent Mobilized

KI

KBr

KCl

NaCl

CaC12

MgC12

Metal mobilization data.

Cu

96.8
83.01

17.22
6.07
2.92
4.47
8.15
3.29

100.5
47.33

12.99
3.04
1.18
1.03
1.59
0.79

33.0
62.34

39.63
10.91
4.11
2.11
1.48
1.93

Ni

109.9
70.64

0.49
6.39
6.41
8.57
26.12
19.77

294.9
85.93

0.13
1.64
2.28
1.93
13.09
7.02

36.0
59.11

0.21
0.81
3.03
2.57
1.51
3.14

METAL

Pb

15.7
51.21

21.08
18.66
3.32
5.69
7.07
1.77

183.0
58.21

3.79
23.85
4.67
3.07
11.48
3.18

10.5
36.07

11.51
7.53
4.02
0.77
6.01
5.84

Zn

2740
86.72

0.02
0.39
1.74
3.02
11.42
4.32

810
85.41

0.01
0.59
4.17
3.24
9.16
5.91

85.2
41.60

0.09
1.67
0.81
0.65
2.22
1.64

* Total metal contents are in ppms whole rock.
** The percent mobilized values are averages calculated from
the amount mobilized relative to the total metal content of

the shales for three trials.

-37-

Fe

44808
68.62

0.00
0.00
0.00
0.04
0.06
0.08

22493
38.35

0.00
0.00
0.00
0.02
0.00
0.00

29757
23.57

0.00
0.00
0.00
0.02
0.01
0.00

EFFECT OF SOLUTION COMPOSITION

If the composition of the leaching solution causes
selectivity in the mobilization process, then the amount of
metal mobilized, should change as a function of changes in
solution composition. The results of experiments studying
metal mobilization, as a function of solution chemistry, are
shown on Figures 5-7 for ionic strengths of 3 and Figures
8-10 for ionic strengths of 1. The data are presented as
the percent metal mobilized with respect to the total metal
contents of the shales. The percentage of metal mobilized
is plotted against the composition of the leaching
solutions. All of the metals are shown except for iron.
Iron is not shown due to the small percentage of Fe
mobilized in all of the experiments. These data can be
interpreted to suggest that solution composition causes
selectivity in the mobilization process.

It is apparent from Figures 5-10 that the degree to
which a metal is mobilized varies with change in solution
composition. The magnitude of the variation in metal
mobilization, associated with changes in solution
composition, is different for each metal which indicates
that the composition of the leaching solution is a factor in
the selectivity of the mobilization process. There also
appears to be regular changes in metal mobilization
associated with changes in the cation and ligand composition

of the solution. A summary follows.

-33-

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Figure 5. Metal mobilization from the New Albany Shale
as a function of salt composition for the 3 ionic
strength solutions with 02 atmospheres.

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Figure 6. Netal mobilization from the Eudora Shale as
a function of salt composition for the 3 ionic strength
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METAL

Figure 7. Metal mobilization from the Heumader Shale as
a function of salt composition for the 3 ionic strength
solutions with 02 atmospheres.

-41...

Mobilization as a Function of Cations in Solution - It is

 

well known that dissolved cations in contact with a sediment
may exchange with cations which are adsorbed onto the
sediment (Krauskopf, 1979). The exchanging power of a
cation in solution is a function of such factors as the
size, charge, hydrated radius, and concentration of the
cation in solution, composition and concentration of the
anions in solution, and the nature of the metal—sediment
bond (Garrels and Christ, 1965; Grim, 1968; Krauskopf, 1979;
and Freeze and Cherry, 1979; Farrah, et al., 1980; Farrah
and Pickering, 1979; Kinniburgh and Jackson, 1981).

With respect to charge, bivalent cations should be more
strongly attracted to exchange sites than univalent cations.
Therefore, given equal concentrations, bivalent cations
should be more effective in mobilizing (exchanging for)
cations from sediments than univalent cations. The results
of the experiments appear to support this idea. The
bivalent cations (Ca and Mg) are, in general, more effective
in mobilizing metals from the shales than are the univalent
cations (K and Na) even though the concentrations of Ca and
Mg in solution are less than the concentrations of Na and K
in solution during the experiments. (Solution ionic
strengths were kept constant in the experiments, however the
molarities of individual ions varied in the leaching
solutions.) This can been seen for all 3 shales (Figures

5-7).

-42-

The relative exchanging powers of the cations used in
this study, should increase in the order K > Na > Ca > Mg
(based on the ionic potential of the cations:
charge/radius) or Na > K > Mg > Ca (taking the hydrated
radii of the cations into account)(Huheey, 1978; Grim, 1968;
Freeze and Cherry, 1979; Farrah and Pickering, 1978;
Krauskopf, 1979; Forstner, et al., 1979). The amount of
metal mobilized from the New Albany shale follows the order
predicted by the ionic potential with the exception of Mg.
For example, Ni mobilization increases in the 31 leaches in
the order KCl < NaCl < CaC12, but decreases in the MgC12
leach (Figure 5). This is observed for each of the metals.
The magnitude of reduction in metal mobilization by the
MgC12 leach is variable. This reduction in metal
mobilization associated with the MgC12 leach may result from
the small size of the Mg ion and the tendency for Mg to be
hydrated in solution (Bathurst, 1971).

Metal mobilization from the Eudora and Heumader shales
follow the order predicted by the hydrated radii. Metal
mobilization increases in the leaches in the order NaCl <
KCl < MgC12 < CaC12 (Figures 6 and 7). Copper and Nickel
mobilization from the Heumader shale are, however,
exceptions. The CaC12 leach is less efficient in mobilizing
Cu and Ni than are the NaCl, the KCl, and the MgC12 leaches.

Explanations for these exceptions are not apparent.

-43-

The changes in metal behavior during mobilization, as a
function of changes in the cations in solution, are
interpreted to indicate that a cation exchange reaction is
important in mobilizing metals from shales. The efficiency
of the mobilization process increases with increases in the
exchanging power of the cations in solution. These data
also indicate that cation exchange reactions can cause
selectivity in the mobilization process. The changes in
metal mobilization with respect to cation composition are
different for each metal, even though the orders of relative
efficiencies remain the same. It is assumed that the metals
which are the most loosely bound to sediment fractions are
preferentially exchanged or mobilized during brine-shale
interactions. It is also possible, that certain cation
compositions of the leaching solutions are more effective in
exchanging for cations adsorbed onto particular chemical

shale fractions, than are other cation compositions.

Metal Mobilization as a Function of Ligands in Solution -

 

The nature of aqueous metal chemical speciation has been
hypothesized to be responsible for the migrationof metals
in a variety of sedimentary environments (Bouleque and
Michard, 1978; Davison, 1979; Giordano and Barnes, 1981;
Higgins, 1980; Lu and Chen, 1977; Macqueen, 1980; Presley,

et al., 1972).

-44-

Shanks and Bischoff (1977), for example, hypothesized
that metal transport in the Red Sea Geothermal system was
due to metal-chloride complexation at elevated temperatures.
Lu and Chen (1977) suggested that organic-metal complexes
may have aided in the mobilization of metals from reducing
sediments. Bischoff, et al. (1981), interpreted thier
experimental data to indicate that metal-chloride complexes
were responsible for the mobilization of metals from
greywackes during seawater and/or brine - sediment
interactions. In this study, the observed metal
mobilization trends as a function of the anions in solution,
may also be explained by metal complexation or ligand
extraction reactions.

The premise of ligand extraction reactions as a cause
of metal mobilization is that, a metal is more
thermodynamically stable in solution as a metal-ligand
complex, than in solid phases during brine-shale
interactions. The stability of a metal-ligand complex in
solution is a function of such factors as the composition
and concentration of the complexing anions in solution, the
pH, the temperature, and the chemical and physical nature of
the cation (Garrels and Christ, 1965; Stumm and Morgan,
1970; Huheey, 1978; and Krauskopf, 1979) If metal
mobilization is, in part, due to ligand extraction, then the
efficiency of the mobilization process should vary with the
ligand composition of the leaching solution. Metals which

form the most stable complexes should be mobilized to the

-45—

greatest extent, while metals which form less stable
complexes are mobilized to a lesser degree.

Pearson's hard-soft, acid-base principle predicts that
type ”b“ cations (soft, large, unpolarizing cations) tend to
complex with ligands in the increasing order F < Cl < Br <
I, whereas type "a” cations tend to complex with the ligands
in the opposite order (Huheey, 1978). The experimental
results can be interpreted in terms of this principle.

Copper and lead are characteristic of type "b” cations,
therefore, they should form complexes with ligands in
solution which increase in stability in the order of Cl < Br
< I and inturn the amount of Cu and Pb mobilized from the
shales should increase in the leaches in the same order.

The amount of Cu and Pb mobilized from the New Albany shale
increases in the leaches in the order KCL < KBr < KI (Figure
5). This is also true for the Eudora and Heumader shales
(Figures 6 and 7). Nickel and Zn, on the other hand, are
more characteristic of type "a" cations and show the
opposite trend, that of decreased mobilization in the
leaches in the order KCL > KBr > KI.

The observed mobilization trends agree, in general,
with the ligand extraction hypothesis. The selectivity of
the mobilization process results from variation in the
stability of metal-ligand complexes in solution. The
greater the stability of the metal-ligand complexes, the

greater the degree of metal mobilization.

-46..

RESULTS OF IONIC STRENGTH 1 LEACHES

In general, the trends observed with respect to the
cation and ligand composition of the 31 leaching solutions
are also observed for the 11 leaching solutions, although
fewer metals are mobilized during the 11 leaches than during
the 31 leaches (Figures 8-10). The reduced efficiency in
metal mobilization associated with the 1 ionic strength
leaches is expected, since cation exchange and ligand
extraction reactions are a function of solution
concentration.

There are differences in metal mobilization with
respect to change in solution ionic strength, however the
data is inconclusive as to the reasons for the changes in

metal mobilization as a function of solution ionic strength.

-47-

 

 

 

 

 

 

[=1
. 02
30.
0 cl
u.)
N
:3 2‘74
3 i
o 1
2:10
.. K E
0- 131mm mg n-9mnm E

 

Cu i Zn Pb
METAL

Figure 8. Metal mobilization from the New Albany Shale
as a function of salt composition for the 1 ionic
strength solutions with 02 atmospheres.

-48-

 

 

   

    
    
   

  

 

 

 

r=1
. 02
3
N20,
3
33 .
O
2:
1o. ,,
at
ii
0‘ m flmaw? ___TER Hm T m
Cu Ni Zn Pb
METAL

Figure 9. Metal mobilization from the Eudora Shale as
a function of salt composition for the 1 ionic strength
solutions with 02 atmospheres.

-[49-

 

 

 

 

 

 

 

30
1 =1
. _ 02
532‘).
N
E
on .
O
z 10 _
o\°
1 V
§
0 m0 I 03$ l'llelS-Ffl -m_T__ ”Ll
Cu Ni Zn Pb
H E TAL

Figure 10. Metal mobilization from the Heumader Shale
as a function of salt composition for the 1 ionic
strength solutions with 02 atmospheres.

-50-

EFFECT OF REDOX

The extent to which the oxidation-reduction state (Eh)
of the leaching environment can influence the mobilization
behavior of metals from shales is dependent on the reaction
mechanisms responsible for mobilization, the metal
partitioning within the shales, and the stability of
metal-ligand complexes in solution. An oxidizing
environment is expected to retard the mobility of most
metals due to the precipitation of metal oxides and the
adsorption of metals onto Fe and Mn-oxides (Garrels and
Christ, 1965; Krauskopf, 1979; Forstner, 1981; Gephart,
1982; Hem, 1978; Kinniburgh and Jackson, 1981). On the
other hand, some metal mobility may be aided by oxidizing
environments. Reduced species, such as sulfide precipitates
and organic material, would undergo oxidation and upon
dissolution release metals adsorbed onto them (Lu and Chen,
1975; Jacobs and Emerson, 1982; Bouleque and Michard, 1981;
Forstner, et al., 1981; Krauskopf, 1981; Garrels and
Christs, 1965). If there were enough complexing ligands,
then the released metals could remain as dissolved aqueous
species rather than precipitating as hydroxides or being
readsorbed. Hence, the ultimate mobility of metals is
dependent on the equilibrium condition established for a

particular environment.

-51-

The results of leaching experiments conducted under 02
and N2 atmospheres, for the 31 solutions and the New Albany
shale are summarized in Figures 11 and 12 and Table 8. The
other shales were not studied. The results indicate that
metals are mobilized under both 02 (oxic) and N2 (anoxic)
atmospheric conditions and that, in general, fewer metals

are mobilized under anoxic (N2) atmospheres than under oxic

(02) atmospheres.

Table 8. Metal mobilization data for anoxic leaches.

LEACH METAL
Percent mobilized

Cu Ni Pb Zn Fe
K1 15.07 2.96 6.44 0.0 0.0
KBr 4.13 4.94 10.69 0.08 0.0
KCl 1.02 3.65 0.73 0.81 0.0
NaCl 1.22 3.69 2.95 0.72 0.0
CaC12 0.91 10.08 1.41 1.18 0.0
MgC12 1.36 10.61 2.06 1.08 0.0
Percent change from 02 leaches (Table 7).
K1 -12.5 +83.4 -73.4 -100.0 -100.0
KBr -32.0 -27.7 -42.7 -79.5 -100.0
KCl -65.1 -43.1 -78.0 -53.4 ~100.0
NaCl -72.7 -56.9 -48.2 -76.2 -100.0
CaC12 -88.8 -61.4 -80.1 -89.7 -100.0
MgC12 -58.7 -46.3 +14.1 -75.0 -100.0

-52-

 

 

°/o MOBILIZED
3
2421
m

 

 

 

 

 

 

 

 

 

o Maggi -im.‘ JEN R E a

Cu Ni Zn Pb
METAL

 

Figure 11. Percent mobilized from the New Albany Shale
(02 atmosphere).

30

 

O
1

3")
(.1 l)
(““11
r'r'
Nb)

 

 

 

 

 

 

 

 

 

 

 

CD
I“
N
E
m ”"7
g
10. '1
\, 3i
j
fir ‘
0 rmfiyfi deggm 93mm i QRMN
Cu Ni Zn Pb
METAL

Figure 12. Percent mobilized from the New Albany Shale
(N2 atmosphere).

-53-

It is clear from Figures 11 and 12, and the data in
Table 8, that the amount of reduction in metal mobilization
(02 to N2) is not the same for each metal. For example, it
appears that Ni is influenced less by REDOX conditions than
are Cu, Pb, and Zn (Table 8). This variation in the amount
of reduction of metal mobilization indicates that REDOX
conditions are a factor which controls the selectivity of
the mobilization process.

In addition, the trends in metal mobilization, as a
function of the cation and ligand composition, under N2
atmospheric leaches are different from those under 02
atmospheric leaches (Figures 11 and 12). The changes in
metal behavior suggest that the relative exchanging power of
the cations in solution change as the REDOX conditions
change, that metal complexation is different under anoxic
conditions than under oxic conditions, and/or that different
shale fractions are attacked under anoxic conditions than
under oxic conditions.

If the exchanging power of the cations and the
stability of metal-ligand complexes in solution do not
change as the Eh of the leaching environment changes from
oxic to anoxic conditions, then no change in the relative
order of metal mobilization, as a function of solution
composition, is expected. However this is not the case.
The relative orders of metal mobilization do change as the

atmospheric conditions are changed.

-54-

If metal speciation and the exchanging power of cations
do not change as a function of REDOX, then the
susceptibility of the various chemical shale fractions to
attack, by different leaching solutions, change as a
function of REDOX. For example, under anoxic conditions the
acid-oxidizable fractions may be more stable or resistant to
metal mobilization by leaching with concentrated brines,
then the acid-reducible fractions. If this is the case,
then the relative order of metal mobilization may change as
a function of Eh. The results of this study are
inconclusive as to the reasons why REDOX conditions
influence the mobilization process, however it is clear that
REDOX conditions do influence the efficiency of the

mobilization process and cause selectivity in the process.

EFFECT OF METAL PARTITIONING

As discussed earlier, metals can exist in several
different solid fractions within a sediment. The chemical
phase in which metals are associated (metal partitioning)
may control the ease in which metals are mobilized from
sediments as well as shales (Presley, et al., 1972; Long,
1977; Forstner, et al., 1981; Gephart, 1982). The
partitioning of a metal results from variation in the
strength of metal-sediment bonds. The variation in
metal-sediment bond strengths could aid in the selectivity
of the mobilization process. Metals which are strongly

bound to the various shale fractions should be more

_55_

difficult to mobilize than loosely bound metals.

It is also possible that the shale fractions will be
selectively attacked by leaching solutions. If this is
true, then the metal partitioning within the shales should
control the mobilization behavior of metals from shales.

For example, if the acid-reducible fraction was selectively
attacked, then the metals associated with this fraction
should be preferentially released during mobilization.

By keeping all variables in the leaching experiments
constant, except for metal partitioning, the affect of metal
partitioning on the mobilization process can be determined.
As an example, Figures 13 and 14 compare the amount of Cu
mobilized from the New Albany, Eudora, and Heumader shales
during the various 31 leaches to the relative Cu
partitioning within the three shales. It is clear from
Figures 13 and 14 that the percentage of Cu mobilized from
the three shales is different for each shale.

Some of the variation in Cu mobilization as a function
of shale type may be due to variation in the total Cu
contents of the shales. However, in the previous example
the total Cu contents of the New Albany and Eudora shales
are essentially the same (96.8 and 100.5 ppms respectively),
yet a greater percentage of Cu is consistently mobilized
from the New Albany shale than from the Eudora shale (Figure
13). Thus differences in Cu mobilization from the New
Albany and Eudora shales may be attributed to the metal

partitioning being different within the two shales.

-55-

It is apparent from Figure 14 that the New Albany shale
has a greater concentration of Cu associated with the
hydromorphic fractions (especially the oxidizable fraction)
than the Eudora shale. Therefore, it may be hypothesized
that more Cu is available ('mobile" metal) to be mobilized
from the New Albany shale, than from the Eudora shale.
However the effect of metal partitioning on the mobilization
process is not as simple as the previous example may imply.
Similar differences in metal mobilization, as a function of
shale type, are apparent for the other metals, though
comparisons similiar to those just made are not possible due

to variation in the total metal contents of the shales.

-57-

.wcHCoprphmn so o>HpmHom .SH opzwflm

nine-mum

m..-0<N-o-xo

 

 

 

 

”mu-m-oaowm

.COHpmNHHHDos so o>wpmHom

.mfi magmas

 

 

~83- Boz .9.
~88 .3- C.»
o u o q ..
I 4 :3
I ‘ tr
e
o :2
:3
:3
3.2- 3323: I
- L.
is: éoe; 4

3.03 »z<m._< >32 0

 

OEZI'IIBOW °/o

-58-

Figures 15-20 present the metal mobilization data for
the 31 KCl leaching experiment as a function of the metal
partitioning within the shales. Figures 15 and 16 show the
percent of Cu and Zn mobilized from the shales as a function
of hydromorphic metal content. As can be seen, the amount
of Cu and Zn mobilized from the shales increase as the
percent of Cu and Zn associated with the hydromorphic
fractions increase in the shales. The trends observed,
however, are not simple or linear.

Figures 17-20 show the percent of Cu and Zn mobilized
from the shales as a function of their relative proportions
within the hydromorphic fractions (reducible and oxidizable
fractions). Again it is apparent that the percentages of Cu
and Zn mobilized from the shales increase as the percentage
of Cu and Zn associated with the reducible and oxidizable
fractions increase in the shales. The observed trends also
are not simple or linear. In any case, variation in metal
mobilization as a function of shale type or metal
partitioning, indicates that the partitioning of metals
within a sediment can influence metal mobilization and cause

selectivity in the mobilization process.

-59-

 

Cu - 31 KCl LEACH

 

S a
,. . A N.A.S. .
I E.S.
l-l.S.
'D 3 «I . ‘
U
..".‘
E 2«
O
s: I
a! 1‘
0 1 I r I I I I I A
20 no do so foo

Figure 15.

% Hydromorphic

Percent Cu mobilized as a function of percent

hydromorphic Cu content of the shales.

 

 

51 Zn- 31 KCl LEACH
, . A N.A.S. I
I 5.5.
1:
a C H.S.
.Z‘.‘ 3 ‘
E?
s: 2 " A
32
1' .
0 r I I ‘1 I I If ‘T I I
20 40 60 80 100
“I. Hydromorphic
FWigure 16. Percent Zn mobilized as a function of percent

hydromorphic Zn content of the shales.

-60-

Cu- 31 KCl LEACH

 

51
k. 9 A N.A.S.
I as.

t . 11.5.
E 3‘ ‘
‘3 2-
Z
:2 1

 

0 ;£;é}.1+2;1;6;20
70 educrble

Figure 17. Percent Cu mobilized as a function of percent
reducible Cu content of the shales.

5. Zn- 3r KCl LEACH

A N.A.S. -

“J I 5.5.
g e H.S.
£1 3‘
'3;
a: 2‘ ‘
33

“ o

0 4r T I I I I

 

 

'8 .12
“lo Reducuble

figure 18. Percent Zn mobilized as a function of percent
:reducible Zn content of the shales.

-6l-

Cu- 31 KCl LEACH

 

 

l

4- A N.A.S. .

a I 6.5.
O H.S.

2 3" l

‘3 2-

z

a: 1. I

0 r ; ; i : Tr ; t e a

20 40 60 80 100

‘lo Oxidizable

Figure 19. Percent Cu mobilized as a function of percent
oxidizable Cu content of the shales.

Zn - 31 KCl LEACH

 

 

51
“.1 ‘ N.A.S. .
g I ES.
'3. 3‘ o H.S.
E
s: 2‘ ‘
o\° 1. .
o i {o3 60' 610‘ 8‘0 rToo

°lo Oxidizable

IPigure 20. Percent Zn mobilized as a function of percent
azidizable Zn content of the shales.

REPARTITIONING OF METALS

The metal partitioning within the shales after
brine-shale interactions is different than the initial metal
partitioning within the shales. Figure 21 is an example
which shows the change in Ni partitioning within the New
Albany shale after leaching with a 31 NaCl solution.
Plotted on the triangular diagram is the initial Ni
partitioning and the Ni partitioning after the 31 NaCl
leaching experiment.

A certain amount of change in the metal partitioning
within a shale must occur when a portion of the metal
content is removed (i.e. mobilized). In the example shown
in Figure 21, approximately 8.6% of the Ni present in the
New Albany shale is mobilized during the 31 NaCl leaching
experiment. The triangular area abc represents the area
where Ni should plot as a result of 8.6 percent of the Ni
present in the New Albany shale being removed from the
shale. If all of the Ni was mobilized from one particular
shale fraction (e.g. the oxidizable fraction), then the
change in the Ni partitioning should be in a direction
directly away from the fraction which lost the metal (e.g.
oxidizable fraction), and the magnitude of change should
correspond to the amount of Ni mobilized (8.6%), i.e. should
jpdot at point b (Figure 21). If the Ni was removed from
aseveral of the shale fractions, the direction of change in
“the metal partitioning would be variable, but the magnitude

c>f change should still correspond to the amount of Ni

-63-

mobilized and plot within or on triangle abc. The change in
the Ni partitioning, however, is greater than what can be

attributed to the mobilization process.

_64_

REDUCIBLE

 

 

 

OXIDIZABLE 50 RESIDUAL

A Initial Ni partitioning
Average Ni partitioning
0 Final Ni partitioning

Figure 21. Example of metal repartitioning.

_65_

Similar changes in metal partitioning are also apparent
for the other metals. Figures 22-33 summarize the changes
in metal partitioning in the shales after leaching as a
function of leaching solution composition. The magnitude of
change in metal partitioning and the direction of metal
repartitioning in the shales is variable. For example, the
amount of change in the Cu partitioning within the shales
(Figures 22, 26, and 30) appears to be less than the amount
of change in the Ni partitioning (Figures 23, 27, and 31).
In both examples, Cu and Ni repartition towards the
reducible fraction corner of the triangular diagrams,
however the exact direction of change and the magnitude of
change vary with the composition of the leaching solution
and the shale type. Regular changes in metal partitioning
as a function of the cation and ligand composition of the
leaching solutions are not apparent on these diagrams.

There is also no apparent correlation between the
degree of metal mobilization (Table 7) and the
repartitioning of metals within the shales. For example the
CaC12 solution is the most efficient Zn mobilizer from the
New Albany shale (Table 7), whereas the greatest degree of
Zn repartitioning occurs after the NaCl leaching experiment
(Figure 25). The metal partitioning data are interpreted to
indicate that metal readsorption onto the various shale

fractions occurs during brine-shale interactions.

-55-

Cu

 

 

 

REDUCIBLE
50
U
Awe
OXIDIZABLE 5° RESIDUAL
e INITIAL 1 =3
Y Kl 02
O KBr
A KCl
[3 NaCl
0 C3 C12
Figure 22. Cu repartitioning in the New Albany Shale.

-57-

Ni
REDUCIBLE

 

 

 

OXIDIZABLE 50 RESIDUAL
INITIAJ. I.-:3

KI

KBr 02

KCl

NaCl

Ca C12

DIO>C].’CI4IO

Figure 23. Ni repartitioning in the New Albany Shale.

Pb
REDUCIBLE

 

 

 

OXIDIZABLE so RESIDUAL
IMHAL 1-3

Kl

KBr 02
KCl

NaCl

CaClz

MgC12

[>‘0 CJI’()-<‘.

Figure 24. Pb repartitioning in the New Albany Shale.
-59-

Zn
REDUCIBLE

 

 

D
F?”

 

OXIDIZABLE SO RESIDUAL

DODDO-(O

Figure 25.

INHML 1-3
Kl

KBr
KCl
NaCl
CaClz
MgClz

Zn repartitioning in the New Albany Shale.
-70-

CU
REDUCIBLE

50

 

 

 

 

OXIDIZABLE I o- RESIDUAL

INITIAL I=3
KI

KBr 02
KCl

NaCl

CaC12

MgC12

t>ou>0-<o

Figure 26. Cu repartitioning in the Eudora Shale.

Ni
REDUCIBLE

50

 

A”?
“00

OXIDIZABLE SO RESIDUAL

INITIAL I=3
Kl 02
KBr

KCl

NaCl
(31:12

tigIIIZ

 

D>C)CJD’O <2.

Figure 27. Ni repartitioning in the Eudora Shale.

-72—

Pb
REDUCIBLE

 

 

OXIDIZABLE 50 RESIDUAL

ImnAL I=3
Kl 02
KBr

KCl

NaCl

CaClz

tlglilz

l> C)CJI> Cl-(lO

Figure 28. Pb repartitioning in the Eudora Shale.

- 73-

Zn
REDUCIBLE

50

 

A

3“

OXIDIZABLE SO RESIDUAL

INHML I=3
Kl 02
KBr

KCl

NaCl

(:a(:lz

A MgC12

   

 

oD>O-(O

Figure 29. Zn repartitioning in the Eudora Shale.

CU
REDUCIBLE

50

 

 

 

OXIDIZABLE 50 RESIDUAL

IMTML I=3
Kl 02
KBr

KCl

NaCl

CaC12

P|g(:lz

DOD>O*.

Figure 30. Cu repartitioning in the Heumader Shale.

-75..

Ni

REDUCIBLE

 

 

 

so D
A
00.
, A
‘F 00
O
OXIDIZABLE so RESIDUAL
o IMTML I=3
Y Kl 02
O KBr
A KCl
Cl NaCl
C) 1:31:12
A M902

Figure 31. Ni repartitioning in the Heumader Shale.

Pb
REDUClBLE

50

 

m
RESID UAL

 

OXIDIZABLE

IMNAL I=3
Kl 02
KBr

KCl

NaCl

CBCIZ

D>otji>0'<’

Figure 32. Pb repartitioning in the Heumader Shale.

Zn
REDUCIBLE

50

 

 

 

OXIDIZABLE SO RESIDUAL

INITIAL I: 3
Kl
KBr
KCl
NaCl
[31:12
iflgi:l2

DOE-"150*.

.Figure 33. Zn repartitioning in the Heumader Shale.

~78-

The hypothesis of metal readsorption is further
demonstrated by the ratios between the initial metal
contents of the various shale fractions and the post-leach
metal contents of the various shale fractions. The ratios
are listed in Table 9. Only the the ratios for the New
Albany shale are shown. Ratios for the other shales are in
Appendix D. A number larger than 1 indicates a gain in
metal content relative to the initial metal content for that
particular shale fraction.

Comparison of the ratio values indicate that the shale
fractions can gain in metal content after brine leaching.
The gain in metal content of the various shale fractions,
relative to the initial metal content, indicates that metals
are readsorbed by the shale fractions. For example, the
ratio values of Cu after the three 31 MgC12 leaching
experiments are 1.95, 1.59, and 1.73 for the reducible
fraction; 1.03, 0.98, and 0.84 for the oxidizable fraction;
and 0.37, 0.57, and 1.06 for the residual fraction. These
values suggest that Cu is mobilized from the oxidizable and
residual fractions and partially readsorbed by the reducible
fraction. Comparing the ratio values for all the leaching
solution compositions indicate that Cu is mobilized from all
three fractions during the potassium salt solution leaches,
whereas during the Cl salt leaches, Cu is mobilized from the
oxidizable and residual fractions and partially readsorbed
onto the reducible fraction. Similar results are found for

the other metals.

_79_

SHALE,

Cu
Cu
Cu

Cu
Cu
Cu

Cu
Cu
Cu

Cu
Cu
Cu

Cu
Cu
Cu

Cu
Cu
Cu

Ni
Ni
Ni

Ni
Ni
Ni

Ni
Ni
Ni

Ni
Ni
Ni

Ni
Ni
Ni

Ni
Ni
Ni

3I

3I

3I

BI

31

31

BI

31

3I

31

31

31

Table 9.

METAL, and LEACH
New Albany Shale

KI

KBr

KCl

NaCl

CaC12

MgC12

KI

KBr

KCl

NaCl

CaC12

MgC12

02 atmosphere

02 atmosphere

REDUCIBLE

0.
o.
O.

0.49
0.49
0.49

0.97
0.86
0.86

2.21
3.53
1.94

1.11
0.74
1.97

1.95
1.59
1.73

0.89
0.93
0.85

1.02
0.97
1.01

1.35
1.33
1.32

1.40
2.20
1.68

0.46
0.49
0.46

0.85
0.61
0.95

-30-

Ratio data for metal partitioning.

OXIDIZABLE

0.83
0.88
0.88

0.87
0.92
0.90

0.97
0.96
0.98

0.91
0.91
0.94

0.99
1.03
0.96

1.03
0.98
0.83

0.76
0.88
0.84

0.75
0.81
0.83

0.67
0.72
0.73

0.47
0.38
0.47

0.46
0.62
0.45

0.58
0.41
0.47

RESIDUAL

0.52
0.67
0.66

1.54
0.83
1.09

0.83
0.96
0.98

1.06
0.81
1.05

0.98
0.98
0.97

0.37
0.57
1.06

1.22
0.95
1.01

1.02
0.85
0.91

1.05
0.77
1.21

1.22
1.14
1.00

1.81
1.99
2.10

0.56
0.95
1.39

Table 9 (cont'd).

METAL AND LEACH

Pb
Pb
Pb

Pb
Pb
Pb

Pb
Pb
Pb

Pb
Pb
Pb

Pb
Pb
Pb

Pb
Pb
Pb

Zn
Zn
Zn

Zn
Zn
Zn

Zn
Zn
Zn

Zn
Zn
Zn

Zn
Zn
Zn

Zn
Zn
Zn

31

31

3I

31

31

BI

31

3I

31

31

3I

3I

KI 02 atmosphere

KBr

KCl

NaCl

CaC12

MgC12

KI 02 atmosphere

KBr

KCl

NaCl

CaC12

MgC12

REDUCIBLE

0.48
0.64
0.66

1.49
1.50
1.73

3.61
3.47
3.67

1.62
1.49
2.20

2.83
2.10
2.41

2.06
1.87
2.10

1.39
1.39
1.19

1.59
1.59
1.59

2.29
2.19
1.99

6.08
6.31
3.94

1.70
1.59
1.90

1.69
1.39
1.79

-31-

OXIDIZABLE

0.04
0.04
0.04

0.04
0.04
0.04

0.30
0.22
0.17

1.16
1.11
2.09

1.26
1.12
0.86

0.53
0.34
0.51

0.93
0.94
0.90

0.93
0.98
0.90

1.02
1.04
1.02

0.61
0.62
0.82

0.88
0.95
0.85

0.81
0.79
0.69

RESIDUAL

0.57
0.84
0.56

0.60
0.87
0.59

0.59
0.59
0.60

0.57
0.51

'0.50

1.15
0.59
0.71

0.96
0.60
0.55

0.49
0.41
0.67

0.71
0.64
0.48

0.72
0.57
0.71

0.51
0.63
0.75

0.86
1.00
1.15

1.26
0.74
1.21

The ratio data also indicates that regular changes in
metal partitioning result from brine-shale interactions.
For example, the Ni ratios for the reducible fraction
(average values 0.89, 1.00, and 1.33) of the New Albany
shale steadily increase with changes in the ligand
composition of the leaching solutions in the order I < Br <
Cl. This is true for each of the other metals in the New
Albany shale. Regular changes are also apparent for the
Eudora and Heumader shales (Tables D3-D4; Appendix D).
Regular changes in metal partitioning, as a function of the
cation composition of the leaching solutions, are not
apparent.

In general, the metal partitioning data is interpreted
to indicate that under oxidizing conditions metals are
predominantly mobilized from the oxidizable fractions of the
shales and, at least partially, readsorbed onto the
reducible and residual fractions. Variation in metal
repartitioning as a function of solution composition
indicates that the different leaching solutions attack the
shales in different manners.

Metal repartitioning under anoxic conditions is
different from metal repartitioning under oxic conditions.
Table 10 and Figures 34-37 summarize the changes in metal
partitioning and the ratio data for anoxic (N2) atmospheric
leaches. The changes in metal repartitioning, as a function

of REDOX, support the hypothesis of metal readsorption.

-82-

Less repartitioning of metals is apparent under
reducing (N2) atmospheric leaches than under oxidizing
conditions. This is consistent with the hypothesis that
metals are mobilized primarily from the oxidizable
fractions, and partially readsorbed onto the reducible
fractions (and residual fractions) within the shales. Fewer
metals are mobilized under anoxic conditions than under oxic
conditions, therefore fewer metals are readsorbed onto the
reducible fractions, and inturn, less metal repartitioning
occurs during anoxic leaches, than during oxic leaches. The
ratio data demonstrates this and may indicate that the
fraction from which metals are primarily mobilized change as

a function of REDOX.

-33-

CU
REDUCIBLE

50

 

51

.n
: --\

OXIDIZABLE 50

 

RESIDUAL
INITIAL [:3

K1 N

KBr 2

KCl

NaCl

(:a(:lz

tlgIZLZ

DODDO-(O

Figure 34. Cu repartitioning in the New Albany Shale
(N2 atmosphere).

“'84-

Ni
REDUCIBLE

SO

 

 

 

OXIDIZABLE so RESIDUAL
INITIAL I=3
KI N2

Figure 35. Ni repartitioning in the New Albany Shale
(N2 atmosphere).

_85_

Pb
REDUCIBLE

SO

 

 

Y
OXIDIZABLE SO RESIDUAL
INITIAL I=3
Kl
KBr
KCl
Natl
CJBCIZ
HgCIz

I>OCI>o 4 0

Figure 36. Pb repartitioning in

the New Albany Shale
(N2 atmosphere).

-86-

Zn
REDUCIBLE

SO

 

 

 

OXIDIZABLE SO RESIDUAL

o ImnAL 1’3
KI
KBr
KCI
NaCl
CaClz
MgClz

DOD>0<

Figure 37. Zn repartitioning in the New Albany Shale
(N2 atmosphere).

-87..

Table 10.

leaching conditions.

METAL AND LEACH

Cu
Cu
Cu

Cu
Cu
Cu

Cu
Cu
Cu

Cu
Cu
Cu

Cu
Cu
Cu

Cu
Cu
Cu

NI
Ni
Ni

Ni
Ni
Ni

Ni
Ni
Ni

Ni
Ni
Ni

Ni
Ni
Ni

Ni
Ni
Ni

3I

3I

31

3I

31

3I

3I

3I

31

31

3I

3I

KI N2 atmosphere

KBr

KCl

NaCl

CaC12

MgC12

KI N2 atmosphere

KBr

KCl

NaCl

CaC12

MgC12

REDUCIBLE

0.11
0.
0.12

0.49
0.61
0.24

0.64
0.60

0.73
0.73
0.61

0.55
0.30

0.37
0.24
0.24

0.93
1.10
0.96

1.29
1.12
1.35

1.02
0.93

0.85
0.94
0.98

0.59
0.53

0.67
0.79
0.63

-88-

OXIDIZABLE

0.79
0.80
0.89

1.01
1.03
1.05

1.16
1.07

1.02
1.05
1.00

1.01
1.11

1.04
1.03
1.04

0.76
0.71
0.71

0.97
0.89
0.98

0.91
0.91

0.71
0.96
0.84

0.86
0.77

0.75
0.92
0.72

Ratio data for metal partitioning under anoxic

RESIDUAL

0.87
0.82
0.27

0.30
0.27
0.31

0.84
0.84

0.31
0.28
0.29

0.60
0.63

0.30
0.31
0.30

0.85
1.05
0.94

1.25
1.64
1.38

2.77
1.23

1.54
0.89
1.62

0.88
1.88

2.06
1.83
1.86

METAL AND LEACH REDUCIBLE OXIDIZABLE RESIDUAL
Pb 31 K1 N2 atmosphere ---- -—-- ----
Pb 0.98 0.83 5.53
Pb 0.75 0.40 2.74
Pb 31 KBr 1.91 0.13 0.65
Pb 1.83 0.39 0.59
Pb 1.78 0.21 0.52
Pb 31 KCl 2.00 0.23 0.61
Pb 2.24 0.20 1.96
Pb ---- ---- ----
Pb 31 NaCl 2.04 0.64 0.66
Pb 2.00 0.78 0.61
Pb 2.16 0.99 0.64
Pb 31 CaC12 1.97 0.47 1.46
Pb 1.98 0.23 0.73
Pb ---- ---- ----
Pb 31 MgC12 1.97 0.47 0.65
Pb 5.00 1.34 1.74
Pb 3.96 0.81 1.24
Zn 31 K1 N2 atmosphere 1.69 1.04 0.64
Zn 1.99 1.04 0.27
Zn 1.89 1.07 0.46
Zn 31 KBr 1.79 1.07 0.52
Zn 1.79 1.13 0.47
Zn 1.99 1.13 0.49
Zn 31 KCl 1.48 1.13 0.66
Zn 1.63 1.15 0.49
Zn ---- ---- ----
Zn 31 NaCl 1.61 1.01 0.54
Zn 1.69 1.04 0.65
Zn 1.58 0.95 0.66
Zn 31 CaC12 1.67 1.09 0.31
Zn 1.79 1.10 0.75
Zn ---- ---- ----
Zn 31 MgC12 1.69 1.18 0.58
Zn 1.59 1.19 0.56
Zn 1.69 1.17 0.44

Table 10 (cont'd).

-39-

CONCLUSIONS

In summary, the leaching experiment results indicate
that the cation composition of the leaching solution, the
ligand composition of the leaching solution, the REDOX
conditions under which mobilization occurs, and the metal
partitioning within the shales influence the efficiency of
the mobilization process and cause selectivity in the
mobilization process. Specifically the results indicate

that:

(1) Different metals are not mobilized to the same degree
within one shale, nor is the same metal mobilized to the
same degree from different shales;

(2) The efficiency of the mobilization process varies as a
function of solution chemistry;

(3) Bivalent cations are more efficient metal mobilizers
than are univalent cations;

(4) The efficiency of the mobilization process increases as
the ionic potential of the cations in solution increase;

(5) The efficiency of the mobilization process increases as
the stability of metal-ligand complexes in solution increase
(Type "b" metals are more efficiently mobilized by large,
soft, polarizable ligands then are type"a" metals, whereas
type "a" metals are more efficiently mobilized by small,
hard, unpolarizable ligands then are type "b" metals.);

(6) The efficiency of the mobilization process is reduced
under anoxic (N2) atmospheric leaching conditions;

(7) The relative order of the amounts of metal mobilized

-90-

from the shales under anoxic conditions are different than
the orders observed under oxic conditions;

(8) The efficiency of the mobilization process is dependent
on the shale type or metal partitioning within the shales;

(9) As a result of brine-shale interactions the metals
repartition within the shales; and

(10) The repartitioning of metals is variable, however in

general it appears that metals repartition to the reducible
shale fractions.

It is clear that the mobilization process is complex
and is a function of a variety of variables and processes.
Interpretation of the data indicates that metal mobilization
from shales by aqueous solutions is selective in the metals
released. The selectivity of the mobilization process is
caused, at least in part, by the cation composition of the
leaching solution, the ligand composition of the leaching
solution, the REDOX (oxidation-reduction) conditions under
which mobilization occurs, and the metal partitioning
within the shales. The ultimate behavior of metals and the
selectivity of the mobilization process is dependent on the
equilibrium conditions established between the various
competing processes which Operate in an environment. The
mechanisms responsible for metal mobilization (mineral
dissolution, cation exchange, and ligand extraction
reactions) preferentially release metals into solution,
while on the other hand the mechanisms responsible for the
removal of metals from solution (adsorption and

precipitation reactions) may also preferentially remove

-91-

metals from solution. Competition between these various
processes control the final behavior of metals during the
mobilization process. Change in the environmental
conditions result in change in metal behavior or metal
mobility.

Based on the results the conclusions of this study are

that:

(l) Cation exchange reactions are, in part, responsible for
metal mobilization and the selectivity of the mobilization
process;

(2) Ligand extraction reactions are, in part, responsible
for metal mobilization and the selectivity of the
mobilization process;

(3) Readsorption of metals onto the various shale fractions
(primarily the reducible fractions) occur during brine-shale
interactions;

(4) Different leaching solutions attack the various
chemical shale fractions in different manners; and

(5) Metals are primarily mobilized from the oxidizable
shale fractions during oxic brine-shale interactions.

In conclusion it is interesting to note that the
interaction of the Eudora shale (a black, organic rich
shale) with a potential ore forming brine solution, of
Na-Ca-Cl composition, could produce a unique metal enriched
solution which is enriched with Pb and Zn, and lesser
amounts of Cu (Figure 38). However, the importance of
selective mobilization during the formation of sedimentary
ore deposits, when numerous source rocks are available basin

wide, needs to be evaluated.

-92-

- NaCl CI CaC12

 

 

 

Is.
1
10- ' w
D .
m «II
N
3
m
o
z 5.
.\° ..

 

 

 

 

     

Cu Fe Ni Pb Zn

Figure 38. Selective mobilization from the Eudora Shale.

APPENDICES

APPENDICES

Appendix A. Initial shale characteristics.

Table A1. Shale mineralogy and age.

SHALE NAME MINERALOGY* AGE

New albany Shale 1, Ch, K, MK, and Q Devonian
Eudora Shale I, Ch, K, and Q Pennsylvanian
Heumader Shale I, Ch, K, Q, and F Pennsylvanian

*

I=Illite, Ch=Chlorite, K=Kaolinite, MX=Mixed layered clays,
Q=Quartz, F=Feldspar

Table A2. Total metal content of shales.

METAL NEW ALBANY* EUDORA HEUMADER MEAN

SHALE**

Cu 96.8 (4.4) 100.5 (28.4) 33.0 (5.8) 39

Fe 44808. 22493. 29757. 48000
(1695.) (1196.) (1823.)

Ni 109.9 (13.0) 294.9(16.0) 36.0 (10.5) 68

Pb 15.7 (4.4) 183.0 (28.5) 10.5 (3.4) 23

Zn 2740. (128.0) 810. (43.0) 85.2 (7.1) 120

% Org. C 8.13 8.38 0.99

* Values are in ppm whole rock. Values in parentheses are
95% confidence intervals.
** Mean shale values obtained from Wedepohl (1968).

-94-

Table A3.

SHALE
(METAL)

(CU)

New Albany
Eudora
Heumader

(Fe)

New Albany
Eudora
Heumader

(Ni)

New Albany
Eudora
Heumader

(Pb)

New Albany
Eudora
Heumader

(Zn)

New Albany
Eudora
Heumader

*

REDUCIBLE

1.688*
0.174
7.673

7.430
4.660
13.826

21.692
6.342
38.620

21.389
28.287
12.845

7.397
17.133
14.080

OXIDIZABLE

81.320
47.161
54.667

61.195
33.699
9.744

48.947
79.586
20.497

29.821
29.924
23.224

79.332
68.276
27.520

Metal partitioning (average distributions).

RESIDUAL

16.992
52.665
37.661

31.375
61.642
76.431

29.362
14.072
40.883

48.790
41.788
63.931

13.271
14.591
58.400

Values are percentages of metals associated with the

various shale fractions.

-95-

Table Bl. Metal mobilization from the New Albany Shale.
New Albany Shale -- 3 Ionic Strength Leaches.

LEACH INITIAL WEIGHT Cu Fe Ni Pb Zn
(grams) (ppms/100mls)

KI 5.00122 1.00 0.01 0.03 0.10 0.03
5.00461 0.85 0.03 0.28 0.11 0.03
5.00408 0.60 0.02 0.02 0.08 0.02

KBr 5.00154 0.31 0.05 0.36 0.13 0.58
5.00483 0.30 0.04 0.34 0.13 0.50
4.99985 0.27 0.04 0.29 0.11 0.46

KCl 5.00484 0.12 0.10 0.38 0.01 2.95
5.00610 0.15 0.19 0.34 0.04 2.78
4.99672 0.15 0.08 0.33 0.02 2.02

NaCl 4.99670 0.28 0.70 0.73 0.06 6.25
5.05536 0.12 1.59 0.26 0.04 2.03
5.05523 0.26 0.78 0.50 0.05 5.02

CaC12 4.98240 0.46 1.59 1.95 0.08 18.56
5.00945 0.33 1.07 1.44 0.07 13.06
4.99236 0.49 3.08 2.04 0.07 19.38

MgC12 5.01680 0.09 0.19 0.75 0.02 3.68
5.00806 0.28 0.31 1.35 0.01 8.44
5.00649 0.09 0.15 0.71 0.01 3.97

Average Percent Mobilized

KI 17.22 0.00 0.49 21.08 0.02

KBr 6.07 0.00 6.39 18.66 0.39

KCl 2.92 0.00 6.41 3.32 1.74

NaCl 4.47 0.00 8.57 5.69 3.02

CaC12 8.15 0.00 26.12 7.07 11.42

MgC12 3.29 0.00 19.77 1.77 4.32

Appendix B.

-96-

Metal Mobilization Data.

Table 82. Metal mobilization from the Eudora Shale.
Eudora Shale -- 3 Ionic Strength Leaches
LEACH INITIAL WEIGHT Cu Fe Ni Pb
KI 5.00023 0.56 0.02 0.02 0.19
5.00179 0.71 0.02 0.02 0.22
KBr 5.00123 0.14 0.02 0.25 2.07
5.00224 0.16 0.02 0.26 2.13
KCl 5.00645 0.06 0.03 0.41 0.46
4.99340 0.05 0.02 0.29 0.42
NaCl 5.04380 0.05 0.18 0.30 0.36
5.00279 0.06 0.24 0.36 0.34
5.02129 0.04 0.34 0.22 0.35
CaC12 4.98067 0.08 0.12 1.56 1.25
5.05715 0.09 0.12 2.03 1.08
5.01102 0.10 0.09 2.07 1.36
MgC12 5.00350 0.03 0.05 0.82 0.28
5.00079 0.04 1.24 0.84 0.07
5.01046 0.04 0.04 1.04 0.29
Average Percent Mobilized
KI 12.99 0.00 0.13 3.79
KBr 3.04 0.00 1.64 23.85
KCl 1.18 0.00 2.28 4.67
NaCl 1.03 0.00 1.93 3.07
CaC12 1.59 0.00 13.09 11.48
MgC12 0.79 0.00 7.02 3.18

-97-

Zn
0.00
0.00
0.21
0.26
2.02
1.70
1.32
1.49
1.30
3.47
3.47
3.47
2.06
2.24
2.78

0.00

0.59
4.17
3.24
9.16
5.91

Table B3.

KI

KBr

KCl

NaCl

CaC12

MgC12

KI
KBr
KCl
NaCl

CaC12
MgC12

Heumader Shale —- 3 Ionic Strength Leaches
LEACH INITIAL WEIGHT Cu Fe Ni Pb
5.00196 0.61 0.02 0.00 0.06
4.99780 0.61 0.04 0.00 0.06
4.99959 0.63 0.04 0.00 0.05
5.00642 0.21 0.06 0.02 0.05
5.00222 0.20 0.02 0.00 0.04
5.00218 0.20 0.21 0.02 0.02
5.00156 0.06 0.11 0.04 0.03
4.98944 0.06 0.09 0.04 0.04
4.99716 0.08 3.00 0.04 0.01
4.93490 0.03 0.32 0.04 0.00
4.99220 0.03 0.21 0.02 0.00
4.98163 0.04 0.55 0.04 0.00
5.03560 0.01 0.18 0.06 0.04
5.01843 0.03 0.22 0.04 0.02
4.98903 0.02 0.13 0.02 0.03
5.00147 0.02 0.04 0.05 0.01
4.98936 0.02 0.04 0.05 0.03
4.98639 0.02 0.13 0.04 0.01
Average Percent Mobilized
39.63 0.00 0.13 3.79
10.91 0.00 0.81 7.53
4.11 0.00 3.03 4.02
2.11 0.00 2.57 0.77
1.48 0.00 1.51 6.01
1.93 0.00 3.14 5.84

-93-

Metal mobilization from the Heumader Shale.

Zn
0.00
0.00
0.00
0.06
0.05
0.11
0.03
0.04
0.04
0.02
0.03
0.04
0.16
0.05
0.06
0.05
0.05
0.06

0.09
1.67
0.81
0.65
2.22
1.64

Table B4.

Metal mobilization under anoxic conditions.

New Albany Shale -- 31 Leaches, Nitrogen Atmosphere.
LEACH INITIAL WEIGHT Cu Fe Ni Pb Zn
KI 5.00488 0.69 0.00 0.15 0.05 0.00

5.01060 0.66 0.00 0.14 0.05 0.00
5.00499 0.68 0.00 0.13 0.06 0.00
KBr 5.00200 0.18 0.01 0.33 0.06 0.11
5.00291 0.17 0.02 0.31 0.07 0.12
5.00870 0.21 0.00 0.35 0.09 0.11
KCl 5.00333 0.10 0.05 0.40 0.01 1.76
5.00099 0.06 0.07 0.37 0.01 1.96
NaCl 5.00923 0.05 0.08 0.26 0.03 1.48
5.00326 0.05 0.01 0.22 0.03 0.84
5.00840 0.06 0.01 0.15 0.01 0.83
CaC12 5.00216 0.07 0.12 0.88 0.01 2.45
5.00731 0.06 0.09 0.91 0.02 2.83
MgC12 5.00497 0.06 0.10 0.75 0.03 2.08
4.99883 0.05 0.05 0.69 0.01 1.41
5.00258 0.07 0.02 0.72 0.02 1.62
Average Percent Mobilized
KI 15.07 0.00 2.96 6.44 0.00
KBr 4.13 0.00 4.94 10.69 0.08
KCl 1.02 0.00 3.65 0.73 0.81
NaCl 1.22 0.00 3.69 2.95 0.72
CaC12 0.91 0.00 10.08 1.41 1.18
MgC12 1.36 0.00 10.61 2.06 1.08

-99-

Table B5. Metal mobilization from the New Albany Shale (11)
New Albany Shale -- 11 leaches
LEACH INITIAL WEIGHT Cu Fe Ni Pb Zn
KI 4.99825 0.41 0.17 0.36 0.00 0.64
4.99743 0.46 0.11 0.47 0.00 0.80
5.00131 0.55 0.12 0.49 0.00 1.10
KBr 5.00064 0.06 0.18 0.30 0.00 0.40
5.00034 0.06 0.11 0.33 0.00 0.46
5.00237 0.04 0.10 0.33 0.00 0.44
KCl 5.00098 0.04 0.17 0.45 0.00 1.14
4.99806 0.04 0.27 0.68 0.00 2.19
5.00396 0.03 0.43 0.44 0.00 1.35
NaCl 5.01976 0.04 0.22 0.33 0.01 1.19
5.02393 0.05 0.16 0.49 0.01 1.74
5.01647 0.04 0.16 0.36 0.04 0.97
CaC12 5.00677 0.17 1.05 1.95 0.00 22.04
5.02032 0.13 0.68 1.56 0.00 15.74
5.01336 0.07 0.50 1.22 0.00 10.34
MgC12 4.99746 0.03 0.94 0.57 0.05 2.02
4.99436 0.03 0.26 0.51 0.04 1.78
Average Percent Mobilized
KI 10.26 0.00 9.04 0.00 0.67
KBr 1.09 0.00 5.61 0.00 0.36
KCl 0.77 0.00 11.61 0.00 1.07
NaCl 0.92 0.01 0.89 2.15 0.89
CaC12 2.67 0.03 30.82 0.00 10.96
MgC12 0.63 0.00 12.42 5.90 1.52

-100-

Table B6.

LEACH INITIAL WEIGHT Cu

KI

KBr

KCl

NaCl

CaC12

MgC12

KI
KBr
KCl
NaCl

CaC12
MgC12

5.00093
5.00151
4.99971
5.00143

5.00080
4.99381
5.00424
5.00166
5.02436
5.02000
5.01554
4.94765
4.99444
4.99962
4.99569

-101-

Eudora Shale -- 11 Leaches

Fe Ni
0.40 0.14 0.32
0.37 0.12 0.30
0.01 0.10 0.22
0.01 0.27 0.29
0.01 0.04 0.26
0.01 0.04 0.25
0.00 0.12 0.30
0.00 0.12 0.39
0.00 0.45 0.27
0.02 0.18 1.50
0.02 0.20 1.44
0.02 0.95 1.38
0.02 0.09 0.74
0.01 0.02 0.67
0.01 0.02 0.60

Average Percent Mobilized

7.56 0.01 1.99
0.19 0.01 1.57
0.21 0.00 1.69
0.00 0.01 2.29
0.43 0.03 10.64
0.45 0.01 7.15

Pb
0.39
0.35
0.06
0.04
0.00

0.00
0.02
0.02
0.01
0.00
0.01
0.01
0.05
0.03
0.05

4.27
0.63
0.00
0.15
0.07
0.67

Metal mobilization from the Eudora shale (11).

Zn
0.12
0.11

0.11
0.14

0.13

0.13
0.11
0.13
0.15
1.57
1.83
1.27
0.63
0.62
0.60

0.29
0.31
0.30
0.30
4.01
2.27

Table B7. Metal mobilization from the Heumader Shale (11).
Heumader Shale -- 11 leaches
LEACH INITAL WEIGHT Cu Fe Ni Pb Zn
KI 4.99956 0.37 0.14 0.03 0.00 0.01
5.01255 0.38 0.21 0.03 0.00 0.01
4.99868 0.36 0.13 0.01 0.00 0.01
KBr 5.00424 0.01 0.32 0.02 0.01 0.03
5.00116 0.01 0.14 0.01 0.01 0.02
5.00262 0.03 0.15 0.01 0.01 0.03
KCl 5.00909 0.01 0.32 0.02 0.00 0.01
5.02083 0.01 0.22 0.02 0.00 0.01
5.01742 0.02 0.15 0.04 0.00 0.01
NaCl 5.00280 0.00 0.21 0.01 0.03 0.01
4.99200 0.00 0.27 0.01 0.02 0.01
4.99602 0.00 0.13 0.02 0.03 0.00
CaC12 5.00470 0.01 0.15 0.01 0.00 0.36
5.04570 0.01 0.22 0.00 0.00 0.00
5.04205 0.01 0.28 0.01 0.00 0.01
MgC12 4.99837 0.01 0.06 0.01 0.02 0.00
4.98360 0.02 0.05 0.01 0.06 0.01
5.00980 0.02 0.06 0.02 0.02 0.01
Average Percent Mobilized
KI 24.87 0.00 1.39 0.00 0.30
KBr 1.08 0.01 0.63 2.97 0.69
KCl 0.93 0.01 1.40 0.00 0.21
NaCl 0.00 0.01 1.28 4.46 0.21
CAC12 0.74 0.01 0.41 0.00 0.26
MgC12 1.40 0.01 1.27 11.99 0.19

-102-

Appendix C.

Metal Repartitioning Data.

Table C1. Metal partitioning in the New Albany Shale.

Initial Metal Partitioning

Reducible Fraction

(percent association)

 

Cu Fe Ni Pb Zn
1.60 7.17 23.42 25.95 7.18
1.70 7.50 22.52 22.28 7.35
1.77 7.62 19.13 15.95 7.66
Oxidizable Fraction '
81.54 58.28 51.65 36.75 75.71 L.
81.76 63.12 51.88 30.63 82.16 -
80.67 62.19 43.31 22.08 80.13 L
31 K1 Leach I
Cu Fe Ni Pb Zn "
Reducible Fraction
0.00 9.69 20.76 25.82 11.39
0.00 9.43 22.28 24.18 11.43
0.00 9.36 20.58 32.86 9.91
Oxidizable Fraction
88.39 62.96 40.52 3.23 81.37
86.29 61.75 47.12 2.42 82.46
86.52 61.20 46.31 2.99 80.08
31 KBr Leach
Cu Fe Ni Pb Zn
Reducible Fraction
0.85 10.25 24.80 51.13 12.42
0.92 10.80 24.67 42.23 11.97
0.90 10.92 24.56 55.16 13.16 E
Oxidizable Fraction
72.44 55.85 41.54 2.05 77.63
83.36 54.63 46.13 1.80 79.29
79.16 55.69 45.41 1.92 79.75
31 KCl Leach
Cu Fe Ni Pb Zn i
Reducible Fraction L
1.76 11.01 31.60 67.06 15.75
1.52 10.79 33.18 67.88 15.24
1.50 10.42 28.68 69.43 14.01
Oxidizable Fraction
83.36 59.45 35.15 7.82 75.33
81.43 60.73 40.79 5.85 77.60
81.45 60.44 35.67 4.55 77.03

-103-

Table C1 (cont'd).

31 NaCl Leach

Cu Fe Ni Pb Zn

Reducible Fraction

3.91 14.48 34.11 35.69 44.80

6.42 15.16 47.72 35.38 43.69

3.39 13.46 41.05 35.11 28.05

Oxidizable Fraction

77.29 65.59 25.89 35.69 48.47

78.82 65.68 18.58 36.80 48.46

78.33 66.50 ' 25.94 46.49 62.40
31 CaC12 Leach

Cu Fe Ni Pb Zn

Reducible Fraction

1.91 12.30 11.61 39.21 13.56

1.23 10.56 10.88 41.78 11.75

3.42 12.24 10.78 45.98 14.53

Oxidizable Fraction

81.16 64.46 26.43 24.40 74.16

82.37 64.04 30.42 31.03 74.91

79.69 61.93 23.71 22.99 69.59
31 MgC12 Leach

Cu Fe Ni Pb Zn

Reducible Fraction

3.55 11.57 29.13 41.13 13.29

2.93 12.03 21.49 50.07 12.35

3.34 12.65 24.35 51.38 15.80

Oxidizable Fraction

89.67 63.50 44.99 14.96 68.82

86.63 64.18 32.83 12.92 75.86

76.27 57.65 27.50 17.62 64.95

-104-

Table C2. Metal partitioning in the Eudora Shale.

Initial Metal Partitioning

Cu Fe
Reducible Fraction
0.17 4.44
0.18 4.82
0.17 4.71

Oxidizable Fraction
45.05 31.33
51.30 37.31
45.14 32.46

Cu Fe
Reducible Fraction
0.00 6.28

0.00 6.70

Oxidizable Fraction
54.44 54.70
52.09 54.53

Cu Fe
Reducible Fraction
0.22 9.30

0.20 9.02

Oxidizable Fraction
52.87 51.30
50.00 49.16

Cu Fe
Reducible Fraction
0.22 9.74

0.21 9.26
Oxidizable Fraction
56.03 51.79
53.86 52.23

Ni

6.26
6.37
6.40

78.20

82.23

78.33

31 KI Leach
Ni

8.68
9.31

77.70
78.17

31 KBr Leach
Ni

9.73

10.00

79.42
78.94

31 KCl Leach
Ni

19.39
16.05

68.77
72.65

-105-

Pb

26.87
30.00
28.00

30.99
29.21
29.57

Pb

7.91
8.54

88.49
87.82
Pb
20.31
21.71

75.32
75.33
Pb
33.66
32.15

59.33
63.61

Zn

17.00
17.13
17.27
67.90
70.32
66.61

Zn
21.34
21.67

67.97
66.02
Zn
22.16
21.99

66.30
64.91
Zn
17.22
17.14

67.50
69.62

Table C2 (cont'd).

31 NaCl Leach

Cu Fe Ni Pb Zn
Reducible Fraction

0.21 9.22 19.72 39.37 18.97
0.22 9.64 19.72 34.14 21.63
0.20 8.81 19.96 42.04 19.52
Oxidizable Fraction

55.16 52.67 68.35 55.41 66.02
57.87 52.13 68.72 56.56 67.14
53.01 52.32 68.42 54.53 65.40

31 CaC12 Leach

Cu Fe Ni Pb Zn
Reducible Fraction

0.14 8.48 10.69 25.38 16.73
0.20 9.65 10.77 29.29 16.69
0.21 9.74 11.00 32.93 16.94
Oxidizable Fraction

34.37 41.86 72.41 56.37 61.65
47.92 37.86 67.10 55.89 66.88
52.41 40.84 67.58 61.65 67.41

3I MgC12 Leach

Cu Fe Ni Pb Zn
Reducible Fraction

0.53 8.83 20.09 36.33 25.40
0.21 6.52 18.24 34.90 20.73
0.39 7.72 19.56 38.77 20.12
Oxidizable Fraction

53.73 40.97 74.33 61.17 59.15
52.83 43.11 72.87 62.67 64.44
46.76 46.13 72.30 59.30 60.88

-106-

Table C3. Metal partitioning in the Heumader Shale.

Initial Metal Partitioning

Cu Fe
Reducible Fraction
7.92 14.38
8.19 12.42
6.91 14.68

Oxidizable Fraction
57.56 10.18
59.84 9.21
46.90 9.85

Cu Fe
Reducible Fraction
6.80 16.83
4.89 15.86
4.72 17.80

Oxidizable Fraction
62.56 14.19
43.97 14.20
40.59 13.99

Cu Fe
Reducible Fraction
14.08 15.03

7.80 15.94

8.92 15.87
Oxidizable Fraction
58.64 12.20
36.56 12.49
40.91 12.07

Cu Fe
Reducible Fraction
17.37 20.93
20.84 21.20
18.08 17.46
Oxidizable Fraction
48.25 13.63
55.34 14.11
51.66 13.56

Ni

30.88
40.40
44.58

17.41
20.20
23.88
31 K1 Leach

Ni

27.41
24.11
23.29

21.13
19.92
20.65
31 KBr Leach

Ni

36.35
37.87
28.88

25.31
27.72
18.65
31 KCl Leach

Ni

52.44
46.25
51.22

21.64
20.56
21.14

-107-

Pb

14.77
7.78
15.98

19.70
23.33
26.64

Pb

37.31
37.47
32.86

2.66
15.43
18.48

Pb

2.00
2.97
12.10

2.00
2.97
2.02

Pb

40.21
40.88
38.70

25.73
23.58
21.87

Zn

14.14
13.60
14.50

27.80
26.25
28.51

Zn

15.79
15.71
17.10

23.24
23.01
23.48

Zn

15.67
15.94
16.52

25.49
27.67
26.75

Zn

17.71
17.57
15.92

23.91
24.96
24.40

Table C3 (cont'd).

31 NaCl Leach

Cu Fe Ni Pb Zn
Reducible Fraction

17.87 18.60 43.98 19.19 16.01
21.24 19.26 52.21 13.75 16.34
24.59 19.56 48.21 13.98 15.21
Oxidizable Fraction

39.93 14.65 24.26 36.46 23.50
45.43 15.24 27.85 41.24 23.74
58.69 14.83 19.45 43.93 23.49

31 CaC12 Leach

Cu Fe Ni Pb Zn
Reducible Fraction

14.13 20.82 24.03 6.27 25.40
10.29 17.29 18.65 8.30 17.69
14.48 17.06 15.41 10.48 18.78
Oxidizable Fraction

70.67 10.25 11.09 37.62 26.51
48.15 10.34 9.49 23.25 25.45
69.79 10.54 7.84 23.96 23.92

31 MgC12 Leach

Cu Fe Ni Pb Zn
Reducible Fraction

18.78 19.96 33.78 13.70 21.65
19.77 19.88 46.36 19.21 21.28
18.19 18.21 31.75 19.09 19.27
Oxidizable Fraction

64.24 9.36 9.56 9.13 23.62
64.52 10.26 13.37 23.06 22.59
66.06 10.63 9.16 28.63 22.53

-108-

 

Appendix D. Ratio data.

Table D1. Ratio data for the New Albany Shale.

SHALE, METAL, and LEACH REDUCIBLE OXIDIZABLE RESIDUAL
New Albany Shale

Cu 31 K1 02 atmosphere 0. 0.83 0.52
Cu 0. 0.88 0.67
Cu 0. 0.88 0.66
Cu 31 KBr 0.49 0.87 1.54
Cu 0.49 0.92 0.83
Cu 0.49 0.90 1.09
Cu 31 KCl 0.97 0.97 0.83
Cu 0.86 0.96 0.96
Cu 0.86 0.98 0.98
Cu 31 NaCl 2.21 0.91 1.06
Cu 3.53 0.91 0.81
Cu 1.94 0.94 1.05
Cu 31 CaC12 1.11 0.99 0.98
Cu 0.74 1.03 0.98
Cu 1.97 0.96 0.97
Cu 31 MgC12 1.95 1.03 0.37
Cu 1.59 0.98 0.57
Cu 1.73 0.83 1.06
Fe 31 K1 1.32 1.04 0.88
Fe 1.27 1.01 0.91
Fe 1.24 0.98 0.92
Fe 31 KBr 1.33 0.87 1.03
Fe 1.31 0.93 0.99
Fe 1.02 0.76 1.02
Fe 31 KCl 1.60 1.04 1.01
Fe 1.55 1.05‘ 0.96
Fe 1.51 1.06 1.00
Fe 31 NaCl 1.91 1.04 0.62
iFe 1.91 1.07 0.61
Fe 2.06 1.08 0.64
er 31 CaCL2 1.69 1.07 0.75
Fe 1.46 1.07 0.83
Fe 1.71 1.05 0.85
Fe 31 MgC12 1.57 1.04 0.79
Fe 1.66 1.07 0.77
Fe 1.57 0.86 0.87

-109-

Table D1 (cont'd).

METAL AND LEACH
RESIDUAL

Ni
Ni
Ni

Ni
Ni
Ni

Ni
Ni
Ni

Ni
Ni
Ni

Ni
Ni
Ni

Ni
Ni
Ni
Pb
Pb
Pb

Pb
Pb
Pb

Pb
Pb
Pb

Pb
Pb
Pb

IPb
Pk)
Pt)

Pt)
Pk)
Pt)

31

3I

3I

3I

3I

3I

31

31

31

31

31

3I

KI

KBr

KCl

NaCl

CaCl

MgCl

KI

KBr

KCl

NaCl

CaCl

MgCl

02 atmosphere

2

2

02 atmosphere

2

2

REDUCIBLE

0.89
0.93
0.85

1.02
0.97
1.01

1.35
1.33
1.32

1.40
2.20
1.68

0.46
0.49
0.46

0.85
0.61
0.95
0.48
0.64
0.66

1.49
1.50
1.73

3.61
3.47
3.67

1.62
1.49
2.20

2.83
2.10
2.41

2.06
1.87
2.10

-110-

OXIDIZABLE

0.76
0.88
0.84

0.75
0.81
0.83

0.67
0.72
0.73

0.47
0.38
0.47

0.46
0.62
0.45

0.58
0.41
0.47
0.04
0.04
0.04

0.04
0.04
0.04

0.30
0.22
0.17

1.16
1.11
2.09

1.26
1.12
0.86

0.53
0.34
0.51

1.22
0.95
1.01

1.02
0.85
0.91

1.05
0.77
1.21

1.22
1.14
1.00

1.81
1.99
2.10

0.56
0.95
1.39
0.57
0.84
0.56

0.60
0.87
0.59

0.59
0.59
0.60

0.57
0.51
0.50

1.15
0.59
0.71

0.96
0.60
0.55

Table D1 (cont'd).

METAL AND LEACH
RESIDUAL

Zn
Zn
Zn

Zn
Zn
Zn

Zn
Zn
Zn

Zn
Zn
Zn

Zn
Zn
Zn

Zn
Zn
Zn

31

31

3I

31

31

31

K1

KBr

KCl

NaCl

CaC12

MgC12

02 atmosphere

REDUCIBLE

1.39
1.39
1.19

1.59
1.59
1.59

2.29
2.19
1.99

6.08
6.31
3.94

1.70
1.59
1.90

1.69
1.39
1.79

-111-

OXIDIZABLE

0.93
0.94
0.90

0.93
0.98
0.90

1.02
1.04
1.02

0.61
0.62
0.82

0.88
0.95
0.85

0.81
0.79
0.69

0.49
0.41
0.67

0.71
0.64
0.48

0.72
0.57
0.71

0.51
0.63
0.75

0.86
1.00
1.15

1.26
0.74
1.21

 

Table D2.

METAL AND LEACH

Cu
Cu
Cu

Cu
Cu
Cu

Cu
Cu
Cu

Cu
Cu
Cu

Cu
Cu
Cu

Cu
Cu
Cu

Fe
Fe
Fe

Fe
Fe
Fe

Fe
Fe
Fe

Fe
Fe
Fe

Fe
IFe
Fe:

Fe:
ZFe
Fe:

31 K1 N2 atmosphere

31

31

31

31

31

31

31

31

31

31

31

KBr

KCl

NaCl

CaC12

MgC12

K1

KBr

KCl

NaCl

CaC12

MgC12

REDUCIBLE

0.11
0.
0.12

0.49
0.61
0.24

0.64
0.60

0.73
0.73
0.61

0.55
0.30

0.37
0.24
0.24

1.85
1.87
1.88

1.89
1.89
1.89

1.79
1.78

1.94
1.86
1.85

1.93
1.84

1.89
1.87
2.04

-112-

OXIDIZABLE

0.79
0.80
0.89

1.01
1.03
1.05

1.16
1.07

1.02
1.05
1.00

1.01
1.11

1.04
1.03
1.04

1.14
1.15
1.19

1.11
1.10
1.13

1.08
1.09

1.22
1.19
1.17

1.15
1.13

1.17
1.18
1.21

Ratio data for anoxic leaches (New Albany Shale).

RESIDUAL

0.87
0.82
0.27

0.30
0.27
0.31

0.84
0.84

0.31
0.28
0.29

0.60
0.63

0.30
0.31
0.30

0.28
0.94
0.76

0.88
0.94
0.89

0.98
0.94

0.79
0.82
0.83

0.55
0.97

0.88
0.87
0.75

 

METAL AND LEACH

N1
Ni
Ni

Ni
Ni
Ni

Ni
Ni
Ni

Ni
Ni
Ni

Ni
Ni
Ni

Ni
Ni
Ni

Pb
Pb
Pb

Pb
Pb
Pb

Pb
Pb
Pb

Pb
Pb
Pb

IPb
Pt)
IPb

Pt)
Pb)
Pt)

31

31

31

31

31

31

31

31

31

31

31

31

Table D2 (cont'd).

KI N2 atmosphere

KBr

KCl

NaCl

CaC12

MgC12

KI N2 atmosphere

KBr

KCl

NaCl

CaC12

MgC12

REDUCIBLE

0.93
1.10
0.96

1.29
1.12
1.35

1.02
0.93

0.85
0.94
0.98

0.59
0.53

0.67
0.79
0.63

0.98
0.75

1.91
1.83
1.78

2.00
2.24

2.04
2.00
2.16

1.97
1.98

1.97
5.00
3.96

-113-

OXIDIZABLE

0.76
0.71
0.71

0.97
0.89
0.98

0.91
0.91

0.71
0.96
0.84

0.86
0.77

0.75
0.92
0.72

0.83
0.40

0.13
0.39
0.21

0.23
0.20

0.64
0.78
0.99

0.47
0.23

0.47
1.34
0.81

RESIDUAL

0.85
1.05
0.94

1.25
1.64
1.38

2.77
1.23

1.54
0.89
1.62

0.88
1.88

2.06
1.83
1.86

5.53
2.74

0.65
0.59
0.52

0.61
1.96

0.66
0.61
0.64

1.46
0.73

0.65
1.74
1.24

 

METAL AND LEACH
31 K1 N2 atmosphere

Zn
Zn
Zn

Zn
Zn
Zn

Zn
Zn
Zn

Zn
Zn
Zn

Zn
Zn
Zn

Zn
Zn
Zn

31

31

31

31

3I

KBr

KCl

NaCl

CaC12

MgC12

REDUCIBLE

1.69
1.99
1.89

1.79
1.79
1.99

1.48
1.63

1.61
1.69
1.58

1.67
1.79

1.69
1.59
1.69

-114-

Table D2 (cont'd).

OXIDIZABLE

1.04
1.04
1.07

1.07
1.13
1.13

1.13
1.15

1.01
1.04
0.95

1.09
1.10

1.18
1.19
1.17

RESIDUAL

0.64
0.27
0.46

0.52
0.47
0.49

0.66
0.49

0.54
0.65
0.66

0.31
0.75

0.58
0.56
0.44

METAL AND LEACH
31 K1 Leach 02

Cu
Cu
Cu

Cu
Cu
Cu

Cu
Cu
Cu

Cu
Cu
Cu

Cu
Cu
Cu

Cu
Cu
Cu

Fe
Fe
Fe

Fe
Fe
Fe

Fe
Fe
Fe

Fe
Fe
Fe

Fe
Fe
IFe

Fe:
Fe:
Fe:

31

31

31

31

31

31

31

31

31

31

31

Table D3.

KBr

KCl

NaCl

CaC12

MgC12

K1

KBr

KCl

NaCl

CaC12

MgC12

REDUCIBLE

o.
0.

1.01
1.00

1.00
1.01

0.99
1.00
1.00

1.16
0.99
1.00

2.01
1.01
2.04

1.36
1.45

1.78
1.83

2.17
2.06

1.99
2.02
1.86

1.80
2.19
2.07

1.70
1.44
1.69

-115-

Ratio data for the Eudora Shale.

OXIDIZABLE

0.97
0.93

1.01
1.06

1.07
1.07

1.13
1.09
1.03

1.17
0.99
1.08

0.86
1.07
1.02

1.64
1.65

1.37
1.39

1.61
1.62

1.58
1.53
1.54

1.24
1.19
1.22

1.09
1.33
1.32

RESIDUAL

0.73
0.77

0.81
0.94

0.75
0.82

0.82
0.71
0.89

1.99
0.96
0.88

0.66
0.85
1.04

0.64
0.64

0.57
0.65

0.66
0.66

0.63
0.61
0.63

0.81
0.91
0.80

0.74
0.85
0.82

METAL AND LEACH

Ni
Ni
Ni

Ni
Ni
Ni

Ni
Ni
Ni

Ni
Ni
Ni

Ni
Ni
Ni

Ni
Ni
Ni

Pb
Pb
Pb

Pb
Pb
Pb

Pb
Pb
Pb

Pb
Pb
Pb

Pb
Pb
Pb

Pb
Pb
Pb

31

31

31

31

31

31

31

31

31

31

31

31

K1

KBr

KCl

NaCl

CaC12

MgC12

KI

KBr

KCl

NaCl

CaC12

MgC12

REDUCIBLE

1.46
1.55

1.59
1.65

3.14
2.59

3.22
3.11
3.13

1.38
1.44
1.51

2.38
2.49
2.54

0.16
0.16

0.52
0.57

1.18
1.09

1.65
1.47
1.79

0.93
1.14
1.12

1.14
1.26
1.38

-116-

Table D3 (cont'd).

OXIDIZABLE

1.03
1.03

1.03
1.03

0.88
0.93

0.88
0.86
0.85

0.74
0.71
0.74

0.69
0.78
0.74

1.73
1.63

1.83
1.86

1.97
2.06

2.19
2.29
2.19

1.97
2.06
1.99

1.82
1.82
2.00

RESIDUAL

1.02
0.93

0.79
0.82

0.86
0.82

0.86
0.82
0.82

0.97
1.32
1.32

0.29
0.54
0.47

0.05
0.05

0.07
0.05

0.16
0.09

0.14
0.27
0.09

0.45
0.39
0.13

0.05
0.05
0.04

METAL AND LEACH

Zn
Zn
Zn

Zn
Zn
Zn

Zn
Zn
Zn

Zn
Zn
Zn

Zn
Zn
Zn

Zn
Zn
Zn

31

31

31

31

31

31

K1

KBr

KCl

NaCl

CaC12

MgC12

REDUCIBLE

1.28
1.29

1.27
1.23

1.08
1.04

1.24
1.15
1.33

0.82
0.82
0.92

1.18
1.07
1.13

-117-

Table D3 (cont'd).

OXIDIZABLE

1.02
0.98

0.95
0.91

1.06
1.06

1.01
1.02
1.01

0.84
0.83
0.92

0.69
0.84
0.86

RESIDUAL

0.75
0.86

0.77
0.86

1.11
0.94

0.83
0.99
0.94

0.88
0.95
1.00

0.85
0.90
1.25

METAL AND LEACH
31 K1 Leach 02

Cu
Cu
Cu

Cu
Cu
Cu

Cu
Cu
Cu

Cu
Cu
Cu

Cu
Cu
Cu

Cu
Cu
Cu

Fe
Fe
Fe

Fe
Fe
Fe

Fe
Fe
Fe

Fe
Fe
Fe

Fe
Fe
Fe

Fe
Fe
Fe

31

31

31

31

31

31

31

31

31

31

31

Table D4.

KBr

KCl

NaCl

CaC12

MgC12

KI

KBr

KCl

NaCl

CaC12

MgC12

REDUCIBLE

0.39
0.58
0.40

1.44
1.28
1.35

2.32
2.32
2.22

2.75
2.87
2.47

1.42
2.17
0.87

1.51
1.51
1.51

1.27
1.25
1.30

1.09
1.13
1.17

1.49
1.53
1.29

1.41
1.39
1.34

1.26
1.45
1.40

1.25
1.28
1.23

-118-

Ratio data for the Heumader Shale.

OXIDIZABLE

0.51
0.73
0.48

0.84
0.84
0.87

0.90
0.87
0.89

0.86
0.87
0.83

1.00
1.42
0.58

0.72
0.69
0.77

1.52
1.59
1.46

1.26
1.26
1.26

1.38
1.45
1.43

1.58
1.56
1.45

0.88
1.23
1.23

0.83
0.94
1.02

RESIDUAL

0.37
1.24
0.95

0.57
1.87
1.55

0.94
0.54
0.76

1.33
0.92
0.34

0.31
1.79
0.19

0.27
0.24
0.26

0.95
0.93
0.99

0.95
0.92
0.95

0.84
0.84
0.92

0.91
0.85
0.82

0.75
1.09
1.07

0.80
0.81
0.86

METAL AND LEACH

Ni
Ni
Ni

Ni
Ni
Ni

Ni
Ni
Ni

Ni
Ni
Ni

Ni
Ni
Ni

Ni
Ni
Ni

Pb
Pb
Pb

Pb
Pb
Pb

Pb
Pb
Pb

Pb
Pb
Pb

Pb
Pb
Pb

Pb
Pb
Pb

31

31

31

31

31

31

31

31

31

31

31

31

K1

KBr

KCl

NaCl

CaC12

MgC12

KI

KBr

KCl

NaCl

CaC12

MgC12

REDUCIBLE

0.69
0.67
0.64

0.81
0.86
0.88

0.92
0.91
0.93

0.87
0.87
0.85

0.75
0.79
0.80

0.82
0.75
0.77

2.11
2.56
2.41

0.15
0.16
0.90

3.75
3.92
3.46

1.52
1.05
1.06

0.44
0.91
1.11

0.45
0.75
0.90

-119-

Table D4 (cont'd).

OXIDIZABLE

1.01
1.04
1.07

1.07
1.18
1.07

0.72
0.76
0.72

0.91
0.87
0.64

0.65
0.76
0.76

0.43
0.41
0.42

0.08
0.58
0.74

0.08
0.08
0.08

1.32
1.24
1.25

1.59
1.73
1.83

1.48
1.41
1.40

0.17
0.50
0.75

RESIDUAL

1.23
1.46
1.45

0.81
0.74
1.52

0.43
0.62
0.47

0.59
0.31
0.54

1.93
2.90
3.77

1.29
0.62
1.35

0.67
0.64
0.71

1.44
1.02
1.29

0.64
0.68
0.71

0.70
0.68
0.63

0.80
1.51
1.38

0.51
0.45
0.49

METAL AND LEACH

Zn
Zn
Zn

Zn
Zn
Zn

Zn
Zn
Zn

Zn
Zn
Zn

Zn
Zn
Zn

Zn
Zn
Zn

31

31

31

31

31

31

K1

KBr

KCl

NaCl

CaC12

MgC12

REDUCIBLE

1.18
1.20
1.27

1.13
1.11
1.20

1.30
1.29
1.27

1.40
1.27
1.15

1.54
1.23
1.92

1.11
1.10
1.11

-120-

Table D4 (cont'd).

OXIDIZABLE

0.88
0.89
0.89

0.94
0.98
0.99

0.89
0.93
0.99

0.96
0.94
0.90

0.82
0.90
0.94

0.62
0.59
0.66

RESIDUAL

1.09
1.12
1.05

1.01
0.94
0.98

1.03
1.01
1.14

1.13
1.12
1.11

0.70
0.94
0.95

0.67
0.69
0.80

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