A. _‘.,__A ' J— __A - h--- «ma: - ~ - A. - 31’: A . I I I IIII I mu I I I I I I II Hog—x Icoo (DUO-b AN EXPERIMENTAL STUDY OF THE TREATMENT OF CYANIDE SOLUTIONS WITH LIME-SULPHUR TO DESTROY ITS TOXICITY Thesis for the Degree cf B.S. MICHIGAN STATE COLLEGE \X/iIber Dean Chapel 1942 IIIIIIIII IIIIIIIIIIIIIIIIIIII __'_ 31293 01098 9881 v I 1‘\ ’3 3 -. .f ‘, An Experimental Study of the Treatment of Cyanide Solutions with Lime~Sulphur to Destroy Its Toxicity A Theses Submittad to the Faculty of MICHIQAN STéTk COLLEGE , of GHICULPUPT Ann AP?IIpn gjzrwcg by Wilbor Dean Chagel Candidate for the Degree of Bachelor of Science July 27,1942 THESIS I r . f, z I I; ’ ACKNOWLIDGHENT The writer wishes to express his appreciation to Mr. E. F..Eldridge for his suggestions an material assistance with the problem. 143084 C ONTENTS Statement of the Problem Survey of the Literature Discussion of the Methods of Waste Diaposal Pending Dilution Acid Treatment and Aeration Oxidation with Potassium ?ermanganate Treatment with Ferrous Sulphate methods of Determining cyanide Sohonbein Test PhenOphthalin Test Prussian Blue Test Silver Cyanide Test Silver Nitrate Test Thiocyanate Test The EXperimental Work Interpretation of the Results Conclusions References "‘3 \O m'fl'fi :0 PCR 11 12 14 14 14 15 15 15 16 17 30 32 STATFKENT OF THE PROBLSM The prieary purzosc or this ex criment 18 to det- ermine the possibility of using a lime-sulohur solution in the treatment of cyanide wastes to remove the toxic effect of the cyanide solutions. The cyanide waste is one of the most important from the standoofint cf pol- ution. There are few industrial wastes which are more hazardous. many of the solutions used for cleaning and plating in industrial slants contain sows form of the metallic cyanides. The disposal of these wastes is often difficult and dangerous. at present titre is not an entirely satisfactory nethod of tre"tnent as all methods are unaccsotable for one or 'ore reasons. The precipitation of cyanide to lower toxic forms with the use of potassium pernanganate is used to some extent by some slants, but the nethod is linited due to the expense invOlved. The disposition of cyanide wastes by the acid reduction method is used by sons plants. The dsoosit on, of evolved gases is a very serious problen, especially in crowded and built up arras. Therefore a new :ethod is being sought which will solve sons of the problens encountrred by the above two methods of handling cyanide wastes. The use of line-sulohur has been sugjestrd as the nossibility of being a new method which will solve problems encounters” by other wethods of cyanide waste treatment. SURVEY OF THE LITERATURE Cyanide wastes may be found in every industrial plant in the country. Automobile factories and other industrial plants have plating rooms in which iron and steel parts are covered with coatings of cooper, nickle, chromium and other metals. There are also the case hardening departnents which use cyanides to a great extent. In the operation of platint races the different parts are suspended in vats containing the cleaning or plating solutions. when the particular secretion is complete the carts are removed from tic bath and rinsed in a vat of water. During the renoving and the transfering of the parts freq the cyanide vats to the rinse water, there are drippinzs Which fall to the floor and are washed down the sewers. Also parts which are not regular, carry over varying anounts of concentrated cyanide sol- utions to the rinsing baths. This tends to keep the concentration of the cyanides up around 400 to 500p.p.m.. The lowest average a plant will have will be around 100 p.p.m. and the wastes fron hardening roons will run up to Very high concentrations of around 20,000 p.p.n.. The wash water vats usually have a continuous flow of water through them so t‘at this tends to keen the cyanide con- oentrations lower. The cyanides are very poisonous and their discharge into streans is a constant senses to fish and aquatic life. Animal life which has access to such strea s, where cyanide wastes say be. is also senaced. If such streams or ponds are not protected, children as well as adults may be killed by coming into contact with water containing cyanides. The physiological action of cyanide is very important and can be explained better by referring to almost any medical book. If the acid, gas, or solid form of cyanide is delt with, care must be taken. Solutions of hydrocyanic acid applied to the skin will cause numbness and a partial loss of sensation. If cyanide is taken internally the central nervous system is at first stimulated and then depressed and finally paralysed. The stimulation is especially marked in the medulla, so that the respiratory center, vasomotor. vagal centers are stimulated, resulting in an acceleration of the respiration, constriction of the blood vessels, and the slowing of the heart. The blood pressure rises on account of vaso- constriction in spite of the slowing of the heart, but soon falls on account of vasodilation. The reapirations are at first accelerated as stated before, but soon becomes slowed and shallow. Coma follows quickly, sometimes preceded by convulsions, death being due to asphyxia. Hydrocyanic acid enters the blood very rapidly and while in the circulation, profoundly affects metabol- ism so that the tissues lose their power of absorbing oxygen. Contrary to previous belief it does not fix oxygen more firmly to the hemoglobin. but forms cyano- hemoglobin which differs from ordinary hemoglobin in its bright red color, a nd which is reaponsible for the bright red color of the blood. Eyes will become dilated and unconsciousness comes rapidly with convulsions. If a person comes incontact with cyanide gas. death is sure to follow, if they get a good dose in about 5-30 minutes. Because of the nature of the wastes there are several important things to remember: 1. There should be complete safety to Operators hand- ling the disposition. 2. The wastes materials cannot be left in dumps or placed where contamination is a possibility. 3. In the handling of the deposition of cyanide wastes, at least two people should work together as a safety precaution. Dr. H. s. Ellis of the United States Bureau of Fisheries makes the following statement about the toxic action of cyanides. "The simple cyanides exert a toxic action on living organisms by reducing or eliminating the utilization of oxygen. As a result of this physio- logical action. cyanide compounds reduce oxygen con- sumption and deve10p symptoms simulating asphyxia.” Professor Karstens' report on the physical effect of cyanide on fish was one of the first complete reports to be published. The trout, used in the experiment. were observed by Professor Kareten to die in rather an unusual manner. They indicated in their notions, efforts typical of trying to get out of the water. They showed all the evidence of suffering from the lack of air. Also a physical effect, which was noticed, was that the gills of the trout assumed a brilliant red color. This indicated that the action of the cyanide was likely through the medium of the blood by the formation of cyano-hemoglobin. This shows that the fish did not die from the lack of oxygen but were effected as humans are to a certain extent. The effect of cyanide on humans having been explained. This action on the fish showed that the hemoglobin carried cyanide instead of oxygen to the portions of the body where oxygen was needed. The cyono-hemoglobin, which must have formed, can be reconverted to hemoglobin if the fish have not been subject to the cyanide for too long a oeriod of time. They may be revived in fresh water, if there is any signs of life, in a short time. Some imoortant results that Professor Kareten found in his experiment with cyanide wastes and fish life are: l. Acids, ferrous sulphate and notassium permanganate cannot be used to destroy cyanide to the point at which it no longer affects trout. An excess of acids or permanganate may be detrinental and cannot be used unless destroyed before reaching the stream. 2. Acids. ferrous sulahate and potassium permanganate can be used for reducing the stream-effluent ratio. If used for this purpose it may become possible for cyanide discharging industries to use streams that might other- wise be too small to dilute the cyanide effluent to the point at which non-effectiVeness to trout is realized. 3. Cyanide in a stream docs not affect the oxygen content for the reason that the atmospheric oxygen maintains the éolubility equilibrium by furnishing oxygen at a rate greater than that of removal due to the formation of oyanate. DISCUSSION OF HE TPTHTDS CF WASTE DISPOSAL FUNDING One of the original methods of cyanide waste disposal is pending. This method is also used today, as a good treatment of cyanide has yet to be fount. Ponding is a simple method to use. Farthen dikes are built around an area of land. These areas are inclosed by a strong fance and must have signs pOStLd on then stating the character of the waste in the area. Tach of these areas should be divided into several ponds so ttat the wastes will not have to be enptyed into a pond until that pond has stood long enough for tests to reveal ttat all tie cyanide has been renoved fron it. The voluno and number of ponds depends upon the volune of waste nroduoed. The cyan de content of the waste waterial in these wonds will gradually decrease and f nally disaooesr entirely if no fresh waste is added to t-e nond. The renoval of the cyanide is due to several factors. They are mainly: dilution by rain water, seenaze, and destruction of the cyanide by either oxidation, hydrolysis, or decomposition. The time required for the complete re oval of the cyanide from the ponds is not definitely known as it undoubtedly depends upon a number of factors. These being rainfall, tenperature, and type of soil, and other factors caused by local conditions. The method of ponding should be considered as the next step better than the discharje of the wastes directly 8 into streams, as it has meny objections. Concrete will stop the objection of seepage, but seepate is one of the factors for the removal of cyanide and yet is one of its objections. If seepage is allowed it ight contam- inate wells in the vicinity, or it nigit gain ae‘ess to swimning holes or any number of thin's that huaans eight cone in centact with. There are also other ob- Jectiens which aid in the removal of the cyanide and yet are an objection because of the danger that they cause. DILUTION Dilution is probably the easiest method of handling the cyanide wastes from the industrial alantfi. This is done by dischar:in5 the wastes into rivers, lakes, or sewers. however plating room wastes run on averace about 400 to 500 p.p.m. of cyanide and the aoeroxi ate toxicity threshold for cyanide is one or less p.p.a.. Therefore it would be very hard for a plant to dilute tieir wastes enough so only to contain one or less p.é.n. of cyanide. The discharging of cyanide wastes into a stream is very dangerous unless the velune of the stress is at all tines sufficient to reduce the cyanide below the fatal dose for aquatic life. Also the waste would have to be diswersod so as t?e local cowcentration of the cy- anide would be prevented. The runn n; of tkr cyanide wastes into the sewer flakes another problee for t*e Scwate plant to solve. Cyanide inhibits the di'estion of sewage Iludge. If cyanide wastes were continually discharged as would be the case in actual practice, the inhibiting effect would be continuous and sludge digtstion would be considersnly inpeded if not entirely checked. There is not a po nt in favor of the disposal of cyanide wastes by the nethod of dilution. There are too many things against the use of this method and it should never be used by any plant for tie disposal of cyanide wastes. except when the body of water. that the waste is emptyed into. is so great that no harm is done. ACID TRLATJEET AND AERATIOH The removal of cyanide from wastes may be accom- plished by means of a commercial sulphuric acid treat- ment followed by the volslitization of the hydrocyanic acid gas that is formed. During the CPOCCBB compressed air should be introduced through pipes in the bottom of the tank. The success of this treatment ascends upon, mainly, four main factors: 1. the acid concentration. 2. the period of aeration (a total of 16 hours is usually sufficient) 3. the completeness of cyanide removal, and 4. the toxicity of the remaining waste. Usually the volume of the cyanide waste is com- paratively small but uou should segregate all wastes not containing cyanides from the cyanide bearing wastes. One other important factor in designing the size of 10 treatment plant needed is the volume of wastes to be treated. A weir box in the sewer lint at sons convenient point will be needed to detcrnine tie flow of wastes. Spilled wastes volune may be detcrnincd b; computing the volume of the vats that contain the wastes. The hydrooyanic gas produced by this treatment process is very poisonous and tierefore the location and dhaign of the equipment must be such that the danger from these fumes is a minimum. The treatment plant should consist of a rubber lined tank of sufficient capacity to hold the daily voLume of waste. The cover of the tank should fit tightly. This cover should have a done in the center which is connected to a tall stack. The wastes say either be pumped into the tank from a sumo connected to the factory drain, or they may flow in by gravity. The commercial sulpheric acid 8 ould be introduced into the tank, from a carboy, by teens of a perforated lead pipe located in the tank above the surface of the waste solutions. The only danger in handling the acid is the adding of it too fast. This would cause too great an evolution of :as and ight cause trouble by not being sufficiently diluted with sri. Compressed air is to be i trodnced through perfor‘ ated lead pines laid in the floor of the tank. Diffusion plates say be usnd instead of lead pipas if so desired. In order to further dilute the Ens, a blower should be located so as to blow a larfc volume of air into the 11 side of the stack. The height of the stack should be at least forty feet high in order to get t‘e gases us above most surrounding buildings. If there are any existing boiler st cks near they might be used. The treat d wastes may be enptied into a stream after a test shows the desired reduction in the cyanide content. OXIDATION WITH PQTASSIU£ PERfATBAHflTZ Potassius pcrnanjsnnte will oxidize tie cyanides in neutral or alkaline solutions with the production of cysnates. 31453: 21531104 3&120 2‘fin ( O! {)4 QI’OH SI’OS’N Using the molecular weights of the above you find that ac?ording to this equation. 1.62 parts by weight of KflnO4 is required to exactly oxidize one part of row or its equivalent of some oth:r cyanide. Tests have shown that the use of potassium per- manganate is entirely practical from the standpoint of Operation and cost of operation. However, the wastes are sonewhst toxic after the treatment if they are emptied undiluted into a stream, lake, etc.. This is found to be esaecially true if the wastes are not aerated. Dr. Nubbs of the University of Vichiqan found that if the wastes were diluted one to one they would not kill fish as had the wastes before hey were diluted. In a large stream this dilution would probably not have to be made. 12 In designing a elant for cyanide wastes treatment by the permanganate method you should build a tank hava ing a happer bottom for the collection of the sludge. this tank does not have to be covered as in the acid treat~ mint method as there are no dangerous gases to contend Iith. The mixing of the permanganate and wastes in the _ tank can be accomplished by means of diffused air as in the acid treatment plant. There should also be a sludge bed of underdrained sand provided for the dewatering of the sludge. The tank may be filled during the day and then treat- ed Just before closing time at night. The aeration may continue for a short time so that the wastes and perman- ganate are throughly mixed. The sludge nay be drawn off the next morning. The cost of the acid treatment and permanganate treatment plants will run about the same. The cost of construction of the acid treatment plant being more than the cost of construction of the permanganate treatnent plant. However. the cost of Operation of the permanganate plant will run somewhat higher than the cost of Operation of the acid treatment plant. TREATIENT WITH FERROUS SUL‘HATE Ferrous sulphate was tried as a means of reducing the cyanide to soae harmless form. This method was tried because it was thought that this method might be quick and also cost less than any other method used at this time. 13 Sons of the facts found out about this method are that: when an excess of alkali is used, the anount of ferrocyanide formed is less than when small+r amounts of alkali are present: that a rise of temperature above . 20°C is harmful to the reaction: that the results are independent of the dilution; that the reactions are as complete in 5 to 10 seconds as they are after long stand- ing; that unless the alkalinity is most carefully adjusted to suit the amount of iron used, an excess of ferrous solution gives no better results than the theoretical quantity, that is required by the equation: Gran 2FeSO4'7H20 K2Fe(FeCN5) exesc4 According to Professor Kareten as far as his ex- periment went, he did not find the ferrous sulphate treat- ment as good as thought. because it did not remove the cyanide to a great enough degree. The remaining cyanide was found to be around 4 p.p.m. and this is enough cyanide to kill fish in about fifteen to twenty minutes. l4 METHODS OF DETERWINING CYANIDE An important factor in work of this kind is the determining the manner in which the results are to be checked after the treatment has been made. host tests that are used with cyanide will give the same reaction with other radicals. There are six tests that give fairly good results, the Schonbein test using guaiac paper. the phenophthalin test. the prussian bule method, the silver cyanide method, the silver nitrate test, and the thiocyanate test which is specific for cyanides and is more sensitive than all the others. These tests are made as follows: (1) The guaiac paper in the Schonbein test is prepared b“ saturation of strips of filter paper with 10 percent alchholic tincture of resin of guaiac which in freshly prepared. These strips are dried and placed in a stoppered vial. They are moistened with a one to 1000 solution of GuSO4 when they are used. The sample to be tested is placed in a flask and acidified with tartaric acid. The flask is closed with a corkiin the bottom of which is a slit for holding the moistened paper above the solution. The contents are warned over a water bath and a blue or blue-green color of the paper indicated that cyanide is present. (2) The phenOphthalln test is sensitive if the preper precautions are ta en. If is a good nethod for determining small quantities of the cyanide. This test depends uaon the production of a red color by the l5 oxidation of an alkaline solution of phenoohthalin to ohenolnhthalein in the preSence of a cyanide and a weak solution of a cusric salt. Tris test is not specificly for cyanides, as other compounds are able to oxidize the phenolphthalin under tiose conditions and give a positive re ction. (3) The Prussian Blue nethod is specific for cyanides and depends upon the formation of a ferro- cyanide. This takes place when an alkaline solution of an easily decomposable cyanide is warned with a sol- ution of ferrous sulphate. Fer low concentrations of cyanide tnis method is very good but for large asounts of cyanide the Prussian Blue wcthod giv:s a very dense blue precipitate. (4) The Silver dyanido nothod drornfls noon the coalescence oroduccd when and excess of silver nitrate is added to a slightly acid solution of cyanide. This test is not Specificly for cyanides. as halogen acids and their salts or certain fatty acids will also produce coalescence with silver nitrate. (5) This test is the some as is used for chlorides in water analysis. This is the Silver nitrate tcst wkich is also used by many to deturnine the orcsence of cyanide. HOWGVtP the chlorides interfere with this detrrrinstion and it cannot be us:d if hydrochloric acid or its salts have access to the was a. lfiuatani paint of tfis silver nitrate detaruinstion is not as well isfinsd in tkis case as is obtained about halfway tirough the titration or 16 just after the double salt fornation is con lstu. (6) The Thiocyanate test which is also 0 ccific for cyanidcs was found to be 5 to 10 times as sensitive as the Prussian Blue tsst. The Thioc'snatr test de- pends upon Hatching of the color of the unknown ssncle and the colors of tte standards. This color stric method is also uscd with the Prussian Elmo test, the silver cyanide test and the Phenookthalin test. It has been found that the Ttiocvanate test will detect .Ol”705 grass of Si! in 1") 1'11. and less ti'an His H'TTC‘llYlt if the volume of the unk1own sawple is reduced to one or two cubic centinetcrs. This is the test used in t*is exocriment and the results found were very satisfactory. 17 THE EXPLIRIL'EEJTAL WORK here were three main things wanted in the work on cyanide wastes. 1. If lime-sulnhur could be used to treat cyanide wastes of high concentrations and re- duce their toxicity far enough to cake thee safe to be emptyed into streams. lakes. or ponds. 2. If time was a factor. That is if the length of time in the treatment of the wastes by lime-sulphur had any effect on the results. Whether the wastes had to stand for one hour or 24 hours after the lime~sulphur had been added to them. And 3. if‘smsll concentrations of cyanide wastes could be treated. These wastes that contained around 500 p.p.m. of cyanide. Cyanide wastes of this concen- tration being found more often than wastes of higher concentration. 80 as to be able to deter ine the value of a lime- sulphur solution in treating cyanide wastes, a known concentration of cyanide was made up. This was treated with the lime-sulphur solution, and then the acount of KCNS present was determined by analysis. The lime-sulphur solution that was used was purchased from the Carrier-Stephens Chemical Company, Lansing, Michigan. The chemical analysis of it is as follows: Calcium Polysulphide 30,01 Calcium Thiesulohate 1.’g Water and other inert ingredients 68.5% Lime and Sulphur in solution 31,5g Sulphur 24.0”: Baume 32 degrees at 15°C In order that a person might have an idea of what 18 range of standards that were necessary for the deter- mination of the cyanide that remained, a rough treat- ment was first made. The solution of KCNS was made up so that 1 ml. of KOHS was equal to 1 mg. of K33. By using their molecular weights it was found that 1.4924 awe. of KCNS in 1 liter of solution should be used. The solution of HON. that was used, was a 10% solution. This consisted of weighing out 100 gas. of KSN and making up the solution to 1 liter. This first set of determinations consisted of taking 50 m1. portions of a 10% solution of KCN and adding vary- ing amounts of lime-sulphur salution, letting these samples stand for 24 hours and then running a rough determination by use of the thiocyanate method. The standards deeded upon had a range of .5 ml. to 5 ml. of KGNS. In that range there were ten different standards with each standard increasing in the amount of KCHS by .5 ml.. The preparation of the standards will be dis- cussed in detail later. This rough determination showed that the ranze, of the standards to be used in further experirent, was between 1 ml. and 2 ml. of Kass used in each standard. The first accurate determination was sade as follows: An accurate prepared 10% HCN solution was distributed in 50 ml. portions into 5 beakers. A sixth beaker contain- ing 50 ml. of distilled water was used as a blank treat- ment to see if it contained any cyanide. To all of these beakers. lime-sulphur was added in varying amounts as 19 follows. Beaker N0. ml. of RON solution Ml. of line-sulphur 1 50 water blank 6 2 SO 6 3 50 7 t 50 8 5 50 9 6 50 10 When the limensulphur solution was added there were two things noted. One was that there was a precip- itate formed and that each solution changed to a yellow color. However this color gradually disaneared in the beakers containing 6, 7, 8, ml. of lime-sulphur. Beakers No. 6 which had 10 ml. of lime-sulphur in it remained a yellow color. This leads one to believe that there was an excess of lime-sulphur added so that upon carry- ing out the tests for cyanide there should be a 1003 reduction of cyanide in that beaker. The asount of precipitate increases also as the am unt of line-sulphur added increases. Second that all of the sanples gave off H23 gas upon the addition of the line-sulphur solution. These samples were covered with watch glasses and were left to stand for 24 hours. At the end of this period of time the samples were filtered to remove the precipitate. Then the solutions were diluted to eresare for the determination of the remaining cyanide. The dilutions used in the rough treatment were used again here as the range of the standards had been determined from the rough treatment trial. 5 ml. of this solution was pipetted into a 230 ml. flask and made up to the 200 ml. mark. Then after being throughly nixed, 10 ml. 26 of this was ta en and dilutcd to 133 ml.. This last dilution was nainly a convenience as the snount of this solution used in the ncsslor tube wos_10 ml. and this made a rosultin* dilution of 40 to 1. After the second dilution was wade, 331 was added so that the solution was just acid to litnus. This was done to renove any excess sulphur which nisit be present and which would interfere with the analysis. she acid- ified sample was heat.d gently to coagulate tke sulohur and also to resove any H S gas that sirht still be 2 present, (J. W. Foshen and co~suthors, Childs and Ball found that heat did wot drive off any averscishlo a cunts of cyanide). I also assumed that br‘njing there sol- utions to a teen reture tint would drive off the has gas would not drive off any cyanide. When the sulphur had been coagulat d and there was not any further odor of H23 the samples Were allowed to cool. They wire then filtered to renove the sulphur. The saddles were now ready for the deteriination of the a cunt of HCNS ore- sent in then. It was found out by exoerience that if the 1 ml. of ferric chloride solution was not added to the couple until the standards were made up that the results would be better. As soon as you add tht ferric ciioriie to sit or the sanolus or the standards tielr color will begin to becoae fa'nter upon standin: a f-w ninutas. That is the reason, I believe, for t7c first two trials 21 being low. If the samples or standards are allowed to stand over night. the color will be alnost entirely gone by the next morning. At this point in the deterqinatlon the standards were made up so that the ferric chloride could he added to the samples and standards at approximately the same time. The solutions that were used in the preparation of the standards are as follows: 10 A 5%‘hydroohlorio acid solution 2. A 10,%'ferrio chloride solution 3. A standard solution of KCHS prepared so that 1 ml. of the solution was equal to 1 mg. of KCN. Nessler tubes were used to hold the amounts of standard solutions and also the samples. The rants of standards used in the first four trials was from 1 ml. of Ross to 2 ml. of K315 and varied fro m ea eh ot‘ er by .2 ml.. The amounts of KCUS, to give the desired range, were placed in the tubes and diluted to about 60 ml. with distilled water. The solutions were then acid- ified with 1 ml. of the 5% H01 solution. The 1 ml. of MD% solution of ferric chloride was added to both the samples and the standards. Both were adjusted accouo ately to 100 ml.. and all solutions were then inverted so as to mix them well. The samples were compared to the standards by comparing the colors. The metering colors representing 23 the amount of KCSS present. The samples that had the largest amount of lime- sulphur added to them showed the deepest color when comparing with the standards. This proved that the more lime-sulehur added to the sample the more KEN that was converted to KCNS until 1005 of the HON had been con- verted to the £033. The first trial made after the rough trial is shown on the too of the third page of the exocrinental work. Trial number two was also made using six samples. One of these again being a sample of distilled water. Trials three and four were made using nine samnles. These nine samples ranged from three through eleven ml. of lime~sulphur used in them. Each differing from the preceeding one by one m1. There were two things that had to be corrected for in figuring out the results, so as to have an accurate figure for the percent of the cyanide removed. One was the purity of the XOR used. The other was to find out how much moisture the HON contained. The KCN used had a purity of 95% and the moisture present in the ROM was so small that it did not effect the results. The obtained results. therefore, were divided by .95 to correct for the purity and give the actual results. The results of this first part of the experiment are listed below and are self exalanatory. 24 Part 1 In part 1 all these results are based on the 24 hour samples. Sample Number 1 2 3 4 5 6 7 8 9 10 Strength of sample All samples were of 10% strength ml. of sample 50 m1. of sample in each used M1. of 6 6 8 9 10 Lime- 6 6 8 9 10 Sulphur 2 3 5 6 7 8 9 10 11 g I 5 6 .1, 8 9 10 ll 7 7 4 4 1 1 mg. of you 0 2.23 2. 9 2.15 2.12 2.08 7 1n p0rt10n O 2023 20 9 2015 2-12 2008 tested 2.40 2.36 2.32 2027 2023 2019 2.15 2.12 2008 2.05 2.40 2.35 2.32 2.27 2.23 2.19 2.15 2.12 2.08 2.05 as. O! O 1.6 IOI I. 5 I. 5 I08 Converted O 101 1.3 106 108 2-0 KCN 05 .6 08 100 102 1.4 1.6 108 2.0 2.1 5.4 .6 .8fi;.0 1.2 1.4 1.6 1.8 2.0 2.0 1 convert- 0 44.8 5002 6004 70.8 8606 ed to CNS 0 4903 5903 7405 85.0 9602 20.8 25.4 34.5 44.2 53.9 63.8 74.4 85.0 96.2 102 16.7 25.4 34.5 44.2 58.4 63.8 74.4 85.0 96.2 97.5 % oonvert- O 4702 5208 6306 7406 9102 ed to CNS 0 52.0 62.0 78.4 89.4 101.1 oorreoted21.9 26. 8 3603 46.4 5607 6703 7804 8904 101.1 108 for 95% 17.6 26.8 36.3 46.4 61.4 67.3 78.4 89.4 101.1 102.5 purity of KCN The second stage of the experi ent was to deter- mine if the length of tine, after the addition cf tte line-sulphur had any effect upon the results. It was proven that one hour of time was as ‘ood as 24 hours. In each of tke deterrinations in the first part, ted for F315 after l {D a portion of the savnle was to hour and another portion was tested for YCWG 2% hours later. The results in each case were the sane. The only error that was found in the exocrinent has been explained as error due to thn waking up of the stands ds or saneles before being ready to conpare. This tine lapse being responsible for the change in color of the samples and standards and therefore making an error in the results. Below is a chart of the results wade after 1 Four and those *ade 24 hours later. lash is forked as to its respective tine. From the chart you may nwtier t“at the first trial did not have as good results as tPe last t ree trials. This is the one that had the crr r due to the dadi.g of color of the stand rds. The samples in this case had} the ferric chloride added to them before the standards were made us and t“nrefore w~tn cone red with the stand- ards they conparcd favorably with t*0se giving low results. The water blank that was carried slow: with each trial did not show any signs of cyanide. In each trial the blank was tested as the samples were and there was no positive water blanks found ’n any of the trials. 26 Sample Number 1 2 3 4 5 5 7 8 9 10 M1. of Lime- 2 3 4 5 6 7 8 9 1011 Sulphur In 24 hrs. ' 0 47.2 52.8 63.6 74.6 91.2 % convert» ' 0 52.0 62.5 78.4 89.4 101.1 ed to CNS 21.9 26.8 36. 3 46.4 56.7 67.3 78.4 89.4 101.1 108 and s 17.6 26.8 36. 3 46.4 61.4 67.4 78.4 89.4 101.1 102.5 corrected . for purity of KCN In 1 hr. % ' 0 52.0 52.8 63.6 89.4 91.2 converted O 56.7 62.4 78.4 89.4 101. to CNS BUG 2109 26. 8 36-3 4604 61.4 67.3 7804 8#05 10101 10205 % corrected21.9 26.8 40.8 46.4 61.4 67.3 78.4 89.4 101.1 102.5 for purity ' of ROM The results as a whole Check quite closely. The error that there is, is probably due to error caused by I my-self in reading the standards. However the error in the first two samples has been explained as due to fading of the color of the samnles. 27 Part three was to find out if snall co.oentrstions of cyanide wastes could be treated. Three different concentrations were used in this part of the experiment. One had a KCE concentration of 500 p.p.m., the second was 1000 p.p.m., and the third was a concentration of 2000 p.p.m. of cyanide. That was the same as making up concentrations of EON of .Ofifl. .11, and .2i solutions. The procedure was much the same as tre one on the higher concentrat‘ons. differing only with the amount of lime- sulphur added and the dilutiions made. With all three of the concentrations, 100 m1. sasples were used. The amount of lime-sulphur used in the .Osi sample was .1. .2. and .3 m1.. filth the .15 sample, the lime- sulphur used was .2. .3. and .4 m1. and .4, .5. and .6 ml. or lime-sulphur were used with the.2£ solution. The dilutions were made such that they would form concentrations that would fall in the range of standards that contained from .2 through .6 ml. of KONG. Upon the addition of the lime-sulphur, to these small concentrations. it was observed trat trere was no noticeable precipitate. However the time element did not effect these sanples either, according to the results. It was also hard to detect any noticeable H25 gas from ‘the samples. The only objectable thing in making the tests for KCNS where such small concentrations of KCE are used is that you are working all the time with tenths of 3 ml.. 28 The difference in color can not be distinguished very easily unless the standards differ by .1 ml. of K318, but a difference of .1 ml. of KCNS makes quite a difference in the results of the sorcenta e of cyanide removed when working with concentrations of 500 p.p.m.. However the results of the work on small concentrations are satisfactory. In working with the .05% solution of ROM, to which was added .1. .2, and .3 ml. of lime~sulphur, it was found that the 100 ml sample to which .1 ml. of lime- sulphur was added that the yellow color left it after about one hour. This showed that there was probably not 100! reduction of the EON. This was proven by the results. The yellow color of the sample that contained .3 ml. of lime-sulphur remained and in this.case there was an excess of limeesulpnur. In the case of .1% and .2e solutions, simular results were found. The sample containing the smaller amount of lime-sulphur lost its color in about one hour and the samples containing the larger amount of lime- sulohur retained their color. The results of part three of this date oinationo are listed below and are self exolainatory. 29 Part 3 1 hour samoles 24 hour samples 100 ml. samples used in each case dilutions made so as the same standards couln be used in each case. A Strength , .051 .051 of sample .10% .101 “89d 020$ 020$ M1. or .1 .2 .3 .1 .2 .3 Lime- .2 .3 .4 .2 .3 .4 Sulphur .4 ‘ .5 .6 .4 .5 .5 M3. Of .499 .099 .498 .499 .499 .498 RON in .499 .498 .498 .499 .498 .498 p0rt10n .498 .498 .497 .498 9498 .497 tested MS. or .3 .0 65 .4 .4 .5 converted .4 .4 .5 .3 .5 .5 KCN .4 .4 .5 .3 .4 .5 .3. .4 .5 .4 .45 .5 .4 .45 .5 .3 .0 .5 .4 .4 .5 .4 .4 .4 % convert-60.1 80.3 100.2 80.3 80.3 100.2 ed to 80.3 80.3 100.2 60.1 100.1 100.2 CNS 80.2 80.3 100.2 60.2 80.3 100.2 50.2 80.3 100.2 80.2 90.3 100.3 80.3 90.3 100.5 60.4 80.3 100.5 80.3 80.3 100.5 80.3 80.3 100.5 x convert-63.3 84.4 105.3 84.4 84.4 105.) Ed to CNS 84.4 84.4 10503 63.3 105.4 105.3 corrected for 95% 84.4 84.5 105.6 63.3 84.5 105.6 purity Of 0303 84.5 105.5 84.4 05.2 105.6 KCN 8#.5 95.2 105.9 64.6 84.5 105.9 84.5 84.5 105.9 84.5 84.5 105.9 A II III I III I I III I .II A I III I II II I I I I II _ III I II II III I IIIII II II . III I III I I I o I II I . III . II I III _ IIIIII I I . II I . V I II I III IIIII I III fl II I I- I IIIIIII I III I.- IIIIIIIIII. III III I. ..I. I IIIIIIII IIIIII I IIIIIIIIIIIIIIIIIIIIII II III -IIII I III IIIIIIIIII I II I I II . . I III . II HMI I II IMII . II . I I I . I . I I III III I I I. - II III < I II I ..IIII I I I {I..-I II IIIv..II..II II «I . .II II ...I. (I) II II. I I I. ..I I 11,] , I‘ll .I. . I. .I .I I. ..I III . . .I.III 1 I... .I . .. II..I. III II I II . III I III! I. III . I.. I I I l . II N I II I _ w . I II II I I I I O u II I I I __. ”..I... H I I I :0 *4 .q‘ “wr‘ - w- I . . I I I I II I I. . .III I I I I. . III IIII .I I .II Ia III I.I I I w I III. I II ~ w r . . . I I .I I . I I IIII ‘ I IIV I I. I I II I I I. I .I.. 1] iIhllt-i‘llll‘l. . IIIIQI'II . I I I . . I II . I I . I . . .. I . I; I‘lilll [III I I | ‘I‘IIIIIIIIIII. I ill- I I I! II. I I! I I. _ .. . . .. .IIIIIIIIIIII......I...II.IIII .I..IIIII.IIII.IIII . I III II II I I . .0 .III I I II . . IIII A p . II II_III III III IIIII_ III III . I- I I I III I I II II I . I m . I I . IIHI _ . I I. I I. III II I I II I I I . I I I I . I I . I IIWI I . _ .. I II I I I I I I . II. I W _ I I .II III .I‘iIIIII! IIIIIIIIII Illilslliltixlilllyty ll»..|.1!l lulIIIn . I‘ll \II II III. FI'III I I.. . II I ..I-..I I .| ..I It; I .I I II .iI It. I II It» .I III . IIIII .. .II ) I. . . _ I III I I I I IIII I . I II I I I I . I . II . I ‘ .. . . III I w . III I w I .I III I I . II . II I I I I _ I I I IIIII v I . IIII l v A I. II II . VIII I - .II I . ILI'II b I V _ I _ I II I IIII II_I IIIIIII I . .L . n . II II . I I I I I IIIIII . v IIII 9 s _ I I III. I.III ..... . II I. K . III I ... . IIIII I..II A I I LII I . I. . . . . III _ ‘ III I. I. . II I . I I. . I ... I.I.II. .. I I- .. I I I . . -IWI f. I _ I ..III. ._ .I. ..I. _ . . IIIIT I. . _. IIII . a . ....I.II .. . ..III_III . n IIIIIIII _ I _ ..I.|I . I. .11 . I .I.. I ,I II.I_I II . I.» II. I I _ . . III I . I III. .I . ._ . . . _ .:II.IIII I _ I . I . III. . III _ . . H II III . 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I I “I. I I I II;; I. III _ L. 3.17: . . -I III _ II III I I . III _ I I I III, w I. IIIII . _ ~I IIHI I I. I III I II I II II I I I II I I I I I II III . III I III. .I... I IIIIII “IIII II I MIIIII IIIIII ..IIIIIII IIIIle III..I.I. . , I III-.. ..I/..I- I II- . I I I I II .I II I II I III . I I I. . I III . _.. III. I I )v. .I I . .I.I .. II I.. I III .. IIII _ .. .v I III .I... IIIVII .. . I .I I .III . _ I . I II. I_ . III * I IIIII ..I . .. IIII.I.. ...... I . .I I H II I . III. . I III. m I II I I W I II . [III I?" III. M ._ III I .H IIHII. IIIIII .. I I . . . .. ..I. . .. ..IIHII . III... I I . ..|,I I . I I I. ..I... I I . .IIII .. . .I.. I . I . . .III m. H II. . H ..I. III .. ... . I I..... ..I.II .I. . . TI I r . . I I .I . I. .,.II..I : ..IIIII: . . ..I I. I. . _ an 9.. vo.ILo>FoJ o\ 30 INTERPRETATION OF RESULTS The results obtained in the course of experiment were very successful in most cases. By turning to the graph on the preceeding page you are able to get a good‘ picture or the results obtained by the use of varying amounts of lime-sulphur with the lOX’KCH solution. The best idea on how much cyanide was actually removed from the solutions is obtained by referring to the column in the tables giving the percent of cyanide removed. The amount of cyanide removed increases as the amount of lime-sulphur solution.added increases. This, of course, is only natural and what you would expect. The results with the LOX solution of KCN proved that lime-sulphur may be used to treat high concentrations of cyanide wastes. The percent of cyanide removed after one hour was the same as the percent removed after 24 hours. This proved that, by the use of lime-sulphur in the treatment of cyanide wastes, a plant could treat its wastes in a very short period of time. This is very advantageous to a plant having a large volume of wastes. This also cuts down on the size of the treatment plant needed. So the cost of a waste treatment plant, it lime-sulphur is used. will be quite reasonable. The third part of the experiment dealt with small concentrations of cyanide wastes. The smaller of the concentrations of KCN used was 500 p.p.m. and this is still somewhat larger than the average concentration of cyanide found in the average waste. At this small 31 concentration every measurment was in tenths of a m1.. It is very hard to do accurate work using such small measurments. The results obtained were satisfactory as to the percent of cyanide removed. However if a part of a drcp in excess was added it would throw the results off. One drOp might contain one or more tenths of a ml.. let from the results obtained from the work on such small concentrations one would be led to believe that small concentrations of cyanide wastes could be treated with good results. 32 CENCLUSIONS From the exocrimental results, it anoears that the liue~sulohur does have the ability to convert the cyanide to a cyanate or thiocyanate w“ich is stable and not toxic to hunans, aniaals, or fish. After the sludje has been renoved frii t*c treated solutions, the effluent way be diluted safely by lett~ ing it flow into a stro”m or lake. The reaction the takes place upon the addition of the lino-suluhur is not a violent one. The only problem to be encountered is the fornation of the sludge. Cn low co centrations of cyanide the sludge will be very small in convarison to tie voluue of wastes and it s ems that it could be dumped into the river along with the trusted liquid. However, if posvible it might be drawn off and placed on a drying bed to rezove the uolsturc. The residue then could be discosad of in a ‘anner desired by the plant. If the concentration of the cyanide runs us around 20,000popom. the voluno of oludre will be firester and if enptyed into a stress it might cause a scum and do- posits along the banks.. This is to be avoided if nos- ible. In a paper published by he Clds Yotor Horks of Lansing, Kichigan, they stated that the sludge they had after using the lime-sulohur as concosed of: 1. Calcium Thiocysnntc 2. Sodium Thiocyanate 3- Calcium Cyanauide 4. Sodium Carbonate 5. Sodium Sulphide 33 The main trouble, with the use of lime-sulphur in the treatment of cyanide wastes, is that if there are other wastes present the results will no be as desired. The Ford hotor Comoany, Desrborn, hichigan tried to use lime-sulphur. their results were unset- isfactory because of other wastes present. For ex- ample, they had a chromste waste present. When the wastes were treated the precipitate was so dense that the problem or its disposal was as great as the orig~ insl problem itself. The lime-sulphur treatment should not be used if the wastes are a combination of several types. Another method might be better. The acid treatment with all its faults docs dcfinitely lower the concentration of cyanide and if it were not for the personal hazards it would probably be the best method. If there had been more time to make further ex- perimentation with this method, it might have been well to carry out the treatment of a combination of wastes. Wastes which would be simulsr to wastes encountered in most plants. The one thing sure from the work on the treatment of cyanide wastes with lime~su1phur is that high concentrations can be treated very well and with good results. The limit or the lowest concentration of cyanide that can be treated with good results is still some in doubt as you are working with such small measurmcnts that one is not sure that his results are correct. The time limit or time factor has been shown not to be important it it is over one hour. Therefore 34 the writer believes that the things desired have been proven but that there are several other questions that will have to be proven before lime-sulphur may be used by all plants in treating their cyanide wastes. 35 RIF? RFNC ES (1) "Industrial Waste Treatment Processes And Plant Design? E. F. Eldridge, fiichigan Engineering Experiment Station Bulletin No. 82 (2) "The Removal of Cyanide from Plating Peon Wastes? E. F. Eldridge, Kichigan ?ngineerin1 fixprrincnt Station Bulletin No. 52 ' (3) "The Effect of Cyanide on Black Hills Trout? The Black Hills Engineer. The South Dakota atate School of nines. Hay 1934 (5) "The Treatment of Cyanide taste with mime-Sulphur to Destroy Its Toxicity? A Thesis by Dale w. Granger, Michigan State College, June 1041. (5) "The Treatment of Cyanide Wastes with Lime-Sulohur to Destroy Its Toxicity? A thesis by Vernon F. Durancesu Michigan State College, June 1042. (6) Practical Physiological Chemistry (7) Ibid. (8) "Steel" Harry L. Campbell, M.S. (9) "Wetal Castings" Harry L. Campbell, T.S. (10) "Disoosition of Cyanide Salts? (11) "Deterninat’on of Small Aseunts of Cyanides by the Formation of Ferric Thiocyanate? J. W. Tllns and Y. Habeshian. NICHILQN STQTE UNIV LIBR’ 99 99 999 999 99999 99 9 1293010989881