Thesis (B.S.)--University of Illinois, 1911.Typescript.Includes bibliographical references

Lauter, Carl J.

English

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THE UNIVERSITYOF ILLINOISLIBRARYraitLSI1rapTHE QUANTITATIVE SEPARATION OFANTIMONY AND TINBYCARL J. LAUTERTHESIS FOR THE DEGREE OF BACHELOR OF SCIENCEIN CHEMICAL ENGINEERINGIN THECOLLEGE OF SCIENCEOF THEUNIVERSITY OF ILLINOISPresented June, 19HUNIVERSITY OF ILLINOISJune 1, 19^1THIS IS TO CERTIFY THAT THE THESIS PREPARED UNDER MY SUPERVISION BYCarl John LauterENTITLED The Quantitative Separation of Antimony and Tin.IS APPROVED BY ME AS FULFILLING THIS PART OF THE REQUIREMENTS FOR THEdegree of Bachelor of Sci eneeIn Chemical EngineeringAPPROVED:head of department of Chemistrythe quantitative sepahatioh ofantimony aid tutBy the tern alloys is meant a metal made "by the fusion of two or moreelementary metals for the purpose of obtaining some particular property/ peculiato the mixture alone.This art of making alloys was Vnown in the earliest ages, for therehave been found in the old tombs and ruins all kinds of articles and weaponmade of bronze and similar alloys.Since that time the production of alloys has rapidly increased, until atthe present time we have an almost infinite number of such metals. Especiallynoteworthy have been the advances made in the production of various steels,containing small amounts of the rare metals, imparting certain valuable nropertito the former; and in the manufacture of babbit or bearing metals. The demandfor good metals of this latter type has been following the rapid growth of theautomobile industry, wherethe best babbit metal obtainable is used, sinceefficiency and life of such high speed engines depends greatly upon the natureof the bearings. Most of these alloys contain the metals tin, antimony, zincand generally some copper. These are present in varying amounts dependingupon where they are used; for small amounts of one or the other will greatlychange the properties of the resultant alloy. Thus, antimony gives a certainhardness whereas too much would make it brittle. Antimony, also imparts tothe metal its peculiar property of expansion upon cooling which insures asnug fit for bearings.It is therefore evident that the problem in hand is the quantitativeseparation of this metal from its group metal, tin, which is consistentlypresent in all brasses, bronze and similar alloys, jnong the many methodsthe following may be mentioned:Digitized by the Internet Archivein 2013http://archive.org/details/quantitativesepaOOIaut-2-(1)In 7/illor*s method, the metals are both in the higher state of oxi-dation. The solution is then treated with Hydriodic acid, whereby, theantimonic chloride is reduced to antimonous chloride, while the stannic chlorideremains unchanged. The equivalent amount of iodine which is thus liberated isthen distilled into a potassium iodide solution end titrated with a dilutesolution of sulphurous acid. Ireat care must be talten in this distillation;therefore making the analysis difficult and not attractive to the industrialchemist.(2)In Garnet *s method antimony is precipitated from tin by the additionof sodium thio sulphate, to a neutral solution of tin and antimony, after anexcess of oxalic acid had boon added to the mixed chlorides of the metals.Oxalic acid must bo in considerable excess or tin will also be precipitated.In precipitating, antimony in this way I found some antimony in the filtrateand results obtained with this method are widely variant.(3)Bresson's method deals with the separation of antimony andarsenic. The metals are precipitated as the sulphides which are then dissolvedin an excess of potassium hydroxide, after which a stream of chlorine is passedthrough the solution, volatilizing the arsenic. This method dees not takeinto account the difficulty of getting the antimonic sulphide dissolved inpotassium hydroxide or the fact that the arsenic is not completely volatilized.He also says nothing about the separation of tin, with which we are chieflyinterested.(4)In Karfiner* (B method the sulphides of antimony, arsenic, and tinare treated with sodium peroxide. This dissolves the sulphides but partially(1) Chemical News Vol. 46, p. 172(2) Zeit. fur Anal. Chemie. Vol. 27, p. 651(3) Anal. Ghemie, Vol. 192, p. 317(4)Zeit. fur Anal. Chemie Vol. 34, p. 596.re-precipitates some of the tin. If the solution is "boiled the tin is allrepreoipitated while the antimony stays in solution, which is later precipitatedas pyro-antimonic acid, by the addition of alcohol. The objection to the useof this method is that the tin is not completely precipitated in boiling andsome of the antimony likewise stays in solution, after the alcohol treatment.(5)In LIcCays method the mixture of the higher sulphides of antimonyand tin are redissolved in five cubic centimeters of hydrochloric acid andafter expelling the hydrogen sulphide a solution of tartaric acid is addedand the filtrate then neutralized with sodium hydroxide. Five cubiccentimeters of a 40 per cent hydrofluoric acid solution are then added andan excess of sodium acetate. The solution is then diluted to about threehundred cubic centimeters and the antimony precipitated with hydrogen sulphide,the fluoride present .prevents precipitation of stannic tin. The antimonyprecipitate is convorted, as usual, into the blar;v anhydrous sulphide. Thefiltrate is evaporated in a platinum dish on the water bath with an additionof sulphuric acid to expel the fluorine, and after dissolving the residue inwater, the tin is precipitated with hydrogen sulphide and treated in the usualway.(6) (6)By Vortmann andlletyl's method, antimony may be quantitativelyseparated from tin by dissolving the mixed sulphides in a little hydrochloricacid, neutralizing by addition of sodium hydroxide and diluting to a volumeof about sixty cubic centimeters. An equal volume of phosphoric acid. ofspecific gravity 1.3 and about twenty five cubic centimeters of concentratedhydrochloric acid are then added and the solution treated at boiling temperaturewith hydrogen sulphide. The blaclc predipitate of antimony tri sulphide iscollected and weighed. The filtrate containing all the tin in solution is(5) Journal American Chem. Society 31, 373-38.(6) Seit. fur Anal. Cheraie 1905- pages 525-535-4.nearly neutralized; diluted with an equal volume of water, v/arraed and thetin precipitated as sulphide and weighed in the usual way. This method isuntrustworthy if nitric acid or other oxidizing agents are present.(?)In Warren's method the antimony and tin are precipitated assiilphides along with the other metals and separated from them by dissolvingin sodium hydroxide. The sulphides are then reprecipitated "by an addition ofhydrochloric acid and they are then dissolved in aqua regia. The nitric acidis driven off and the tin precipitated as ferrocyanide; no such compound "beingknown for antimony. The objection to this method is in the use of sodiumhydroxide in dissolving the sulphides of antimony and tin. Unless certainprecautions not given under this method are taken the tin is partiallyreprecipitated and antimony, if in the higher state of oxidation is verydifficultly soluble in alkalies.(8)Low's method is the direct titration of both metals in the presenceof each other. The solution of the metals or sulphides in sulphuric acidis titrated with potassium permanganate, whereby the antimony is oxidized.The tin is then reduced with metallic antimony and titrated with a solution ofiodine. This method usually gives low results for tin.(9)Vietz's method is a modification of Low's. Here the tin andantimony or sulphides are dissolved in concentrated sulphuric acid. This isdiluted to about two hundred cubic centimeters and the antimony which ispresent in the antimonous state is titrated with standard permanganate solution.After titrating with permanganate, about one gram of finely powdered antimonyper 5/10 grams of alloy and 25 cubic centimeters of concentrated hydrochloricacid are added to reduce the tin. Carbon dioxide is then passed through theflask, while it is being boiled, to prevent re-oxidation of the tin. The(7) Ghem. News Vol. 57, p. 124(8) Jour. .American Ghem. Society Vol. 29, p. 66(9) Ghem. Engineer Vol. XII, p. 116.-re-solution is then rapidly cooled, continually passing carbon dioxide and thenquickly titrated with iodine, standardized against tin and carried out in thesarae mariner as above described.The analysis is reliable only - hen the process is carefully carriedout, the titrations require a little practice before reliable results can beobtained.(10)Glarke's method depends upon the fact that antimony is completelyprecipitated from an oxalic acid solution while stannic tin is not. Thealkaline solution of the sulphides of antimony and stannic tin are placed ina flask and treated with six crams of pure potassium hydroxide (.3 grams ofthe combined metals being present) . To this mixture enough 30 per centhydrogen peroxide is added to completely oxidize the tin and any thiosulphatewhich may have been formed. The excess of hydroren peroxide is boiled offand the solution cooled, after which five times the weight of the combinedmetals, of oxalic acid is slowly added and then vigorously boiled to removeany surplus hydrogen peroxide. Through this volume of the solution, whichis about 100 cubic centimeters, a rapid stream of hydrogen sulphide ispassed. After a short time the volume is increased and hydrogen sulphidepassed for fifteen to twenty minutes longer.The antimony pentasulphide is filtered through a Gooch crucible, driedin a stream of carbon dioxide at 300° for an hour and weighed as antimonicsulphide. The filtrate is evaporated to about 200 cubic centimeterstransferred to a platinum dish and electrolysed at 60° with a current of .2amperes, and weighed as metallic tin.(expesilieittal wohk)It has been found possible to get a clear solution and a clean separation(10) Chem. News Vol. 21, p. 124. Zeit. Anal. Chem. XLI 1.of antimony and tin from the rest of the sulphides of croup two by the use ofpotassium hydroxide. The mixed sulphides are filtered and transferred to abeaker, a little hydrochloric acid is added and this is then heated . Amixture consisting cf 100 cubic centimeters of 5 per cent potassium hydroxideand one cubic centimeter of 30 per cent hydrogen peroxide, is then added untiljust faintly alkaline to litmus. The mixture of sulphides and alkali is thenheated to boiling upon which the red coloration disappears! and more of thepotassium hydroxide can be added without fear of reprecipitating any tin.If larger amounts of hydrogen peroxide ore used, some of the copper sulphide,if present, will be oxidized and go along into solution with the antimony andtin sulphides. Having the sulphides of antimony and tin dissolved completelyin potassium hydroxide, the next question was to get a good separation of thetwo.I first tried the application of Clarke's method. As the sulphideswere dissolved in potassium hydroxide jnd hydrogen peroxide it was not necessaryto add any more peroxide and boil to oxidize sulpho salts, as the antimony andtin are both present as oxy salts. The solution of the sulphides was stronglyacidified with Oxalic acid and boiled to remove any free peroxide. A streamof hydrogen sulphide was then passed throu -h the hot solution and the antimonyprecipitated out as a dark reddish granular precipitate, which filteredrapidly and clearly. A test for tin in the precipitate showed its absence then.The filtrate was then neutralized with ammonia and ammonium acetate added whichprecipitated the tin as hydroxide. The predit>itate was T*ery gelatinous andoccupied a large volume which made it difficult to filter and wash. Thisdifficulty was overcome by the use of a filter pump; using a gentle suction.In order to find a quicker way for the determination, the readtionsof various reagents upon the alkaline solxitions were tried out.-7-Separate solutions containinc only tin and only antimony were tried, andgive the following tabulated results:Reagent Tin Sulphide in Antimony Sulphide inPotassium Hydroxide Potassium HydroxideToAcetic acidneutral Excess ofpoint reagentwhite ppt, no change?o neutral Excess ofpoint reagentno ppt. no ppt.Sodium bicarbonate it ii ii ii ii ii ii iiPotassium persulphate ii ii ii ii •i ii ii iiAmmonium persulphate ii ii ii ii n ii ii tiOxalic acid n ii ii ii ii ii ii iiPotassium ferri cyanide green " " " ii ti ii nPotassium ferrocyanido white " " ii ii ii iiPhosphoric acid " n redis solves ii ii ii iiHydrochloric acid ii ii n ii ii ii iiNitric acid ii ii it ii ii ii iiAluminium no action metallic 3b. metallic 3b.From these facts we seem to have reached an ideal separation, foracetic acid, potassium and ammonium persulphate, sodium bicarbonate, andphosphate all give a complete separation of tin, leaving none in solution,while they are without absolutely any visible action at all upon the antimonysolutions.A mixture of the two metals was then analyzed using about .1 gramsof each metal, -his was precipitated with hydrogen sulphide, filtered anddissolved in the usual way in a 5 per cent solution of potassium hydroxidecontaining 1 cubic centimeter of 30 per cent hydrogen peroxide in onehundred cubic ceiitimeters of solution.-8-After obtaining a clear solution about one cubic centimeter moreof hydrogen peroxide and 25 cubic centimeters of potassium hydroxide wasadded, so as to be sure to have the tin and antimony both completely oxidised.This v/as then boiled to completely expel the excess of peroxide, after whichacetic acid was added until the solution was distinctly acid. A whiteprecipitate was formed which quickly settled to the bottom and filtered easilyand clear.This precipitate was then dried and ignited and weighed as stannicoxide, but the results were all much higher than the amounts of tin taken,although somewhat close to each other.Results of the Analysis.Tin taken Tin found.0974 grams .1217 grams.0974 " .1208 ".0974 •» .1298.0974 " .1107The fact that the weights of tin found agreed as closely as theydid gave a suggestion that perhaps a compound of antimony and tin was found.This may have been a tin antimonate having a definite composition, in whichcase this would have been as good as a clean separation of the two metalsas the antimony remaining in solution could be determined later. If notenough antimony were present in the beginning a known amount of a standardsolution could be added to combine with all the tin present.In order to verify this, another series of analyses were run usinga fresh solution of tin and antimony. The results were as follows:Tin taken Tin foundI .0689 grams .0818 gramsII .0689 » .0795 «III .0689 » .0808-9-Here again the weights of tin found v/ere higher than amounts takenbut the percentage difference was not the same as in the first set of determin-ations and results v/ere not as concordant. This proves beyond a doubt thatthe antimony must be carried down mechanically with the tin.Potassium persulphate and ammonium persulphate and sodium bicarbonateall behaved similarly with the mixed sulphides in potassium hydroxide; allbringing down antimony with the tin precipitate. Phosphoric acid when triedon the mixtures gave a precipitate which was impossible to filter and uponheating went back into solution.From the results obtained it seems sure that there is no definitecompound formed between antimony and tin as the percentage increase in weightis not constant under similar conditions. It may, however, be possible tofind a way to get a complete separation with varyinr* conditiorjs or >>yreprecipitation. Otherwise the long method of Clarice's is applicable to theconditions in which the two sulphides are left, after separating from theother elements of the same group.-10-BIBLIOGRAPHY.(1) teller.(2) Garnot( 3) Bunsen(4) Karsner(5) L!cCay(6J Vortnann(7) Warren(8) Low(9) Viety(10) ClariceChenical Hews, Vol. 46, p. 172it3eit. fur Anal. Chenie. Vol. 27, p. 651it"eit. fur Anal. Chenie. Vol. 192, p. 317i»Zeit. fur Anal. Chemie. Vol. 34, p. 596Jour. Aner. Chen. Society Vol. 31, p. 373-81,»tZeit. fur Anal. Chenie 1905, p. 525-35Chen. News Vol. 57, p. 124Jour. Aner. Chen. Society Vol. 29, p. 66.Chen. Uncineer Vol. 12, p. 116Chen. Hews, Vol. 21, p. 124

The quantitative separation of antimony and tin

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Typescript.Thesis (B.S.)--University of Illinois, 1911.Includes bibliographical references.Mode of access: Internet

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The quantitative separation of antimony and tin /

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The quantitative separation of antimony and tin

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