Semi-Works Development of a Germanium Extraction Process Citation Burks, Jesse Carhart (1922) Semi-Works Development of a Germanium Extraction Process. Bachelor's thesis, California Institute of Technology. doi:10.7907/TE5X-TQ90. https://resolver.caltech.edu/CaltechETD:etd-04192004-161549 Abstract No Abstract. Item Type: Thesis (Bachelor's thesis) Subject Keywords: Chemical engineering Degree Grantor: California Institute of Technology Division: Chemistry and Chemical Engineering Major Option: Chemical Engineering Thesis Availability: Public (worldwide access) Research Advisor(s): Lacey, William Noble Thesis Committee: None, None Defense Date: 1 January 1922 Record Number: CaltechETD:etd-04192004-161549 Persistent URL: https://resolver.caltech.edu/CaltechETD:etd-04192004-161549 DOI: 10.7907/TE5X-TQ90 Default Usage Policy: No commercial reproduction, distribution, display or performance rights in this work are provided. ID Code: 1417 Collection: CaltechTHESIS Deposited By: Imported from ETD-db Deposited On: 22 Apr 2004 Last Modified: 03 Oct 2019 23:08 Thesis Files Preview PDF (Burks_jc_1922.pdf) - Final Version See Usage Policy. 890kB Repository Staff Only: item control page

Alles, Gordon A Ames,Panl R Beman;illerd <3: Bridgeford, Prank R. Burks, Gillies, Robert W Jesse C Knight,Alfred ¥ Reynolds, Maynard 5S Ritchie,Chéerles Fisher Vesper, Warner, Howard G Lester 0° THESSS 1922 A new acridine dye. The specific heat capacity of heavy pétroléum products. ™he Tiowig procese for caustic soda using trana as a rew materio?, A process for the utilization of pyrite ash. Seni-works development of a germanium extraction process. An attempt to dehydrogenate cottonseed oil. Perchloric acid from ammonium perchlorate and oxides of nitrogen. The utilization of a denosit of magnesite located nesr Porterville,California as a source of raw materiel for the manufacture of C.P. Epsom salts. An investigation on the production of sodium thiosulfate from trona. The preparation of carbon monosulphide and hydrocyanic acid by the use of activated carbon. The reaction between nitrogen and methane in the silent electric discharge. California Institute of Technology Pasadena, California CLASS OF 1922 Department of Chemistry Wndergraduate Theses of Gordon A.Alles Paul R.Ames Willard J.Beman rank R.Bridgeford Jesse C.Burks — Robert W.Gillies Alfred ™.KXnight Maynard 5.Reynolds Charles *isher Ritchie Howard G.Vesper Lester 0. Warner Semieworks Development of 2a Germanium Extraction Process Thesis by vesse CG. Burks In partial fulfillment of the requirerents for the degree of Bachelor of Science in Chemical Engineering California Institute of Technology Pasadena, California 1922 i. Semi-works Development of a Germanium Extraction Process . General Considerations. The existence of Germanium in the dine Sulvhide ores of the Joplin, Mo. district is generally known. “The element, combined as the oxide GeO. is present to the extent of approximately 0.01% . ‘this fact is of no particular interest as far as the economical extraction of the element is concerned, but in addition it is found that during the process of refining of the zine ore, in the production of gine oxide, the residue of zine oxide remaining in the retorts contains Germanium Oxide to the extent of approximately 0.24% - This fact is significant in that it furnishes a source of the otherwise extremely rare @lement in a comparatively concentrated form. Through Dr. A. A. Noyes it was possible to obtain two hundred pounds of the crude gine oxide from the New Jersey dine Co. , this sample being used in the work described in this paper. | Purpose of Investigation. In view if the fact that there had been little, if any development of a method of obtaining Germanium or its compounds in any appreciable quantities, and also due to the fact that a demand had been created for enough of the element to carry on an extensive investigation of its proverties, the matter of large scale extraction was looked into. the purpose of this work was therefor to attempt & development of a semi=works scale process ,whereby Germanium or one of its related compounds could be obtained in @ practical and economical manner from crude zine ' oxide. Previous Work . Preliminary work on this problem was started by Kr. Phillip Clarke in January, 192%, and continued until June of that year. A thorough survey of the properties of Germanium and its compounds was made and previous methods of extraction ifivestigated, followed by the develonment of a more practical method of extraction applicable to large scale operation. The results of his investigations appear in his thesis report : "The Extraction of Germanium from Crude dine Oxide." “Clarke found that the erude: zine oxide contained Germanium Uxide (Ge02) to the extent of 0.24% and arsenic oxide to approximately twice that amount. He points out that practically ali methods of extraction prior to his investigatioms, involved a distillation of the dissolved germanium bearing substance, in which a separation was made through the volatility of Germanium Chloride. There were several modifications of this general procedure, Some separating the Germanium from the arsenic and gine chlorides in the first step, by distillation in the presence of an oxidizing agent, under which conditions the arsenic chloride was non volatile. Others, distilling over both the Germenium and arsenic in the first step, rely on redistillation for separation. None of these methods however, did away with the necessity of distiliing large . quantities of an extremely corrosive liquid. The disadvantages of such a distillation are manifest. - A consideration of the fact that Germanium tas recovered from the distillate in the above mentioned distillations by precipitation with hydrogen sulphide led Clarke to investigate the possibility of making the first step in the process a precipitation of the dissolved Germanium Oxide. This proved to be practically quantitative the procedure being as follows ie 10 gr. of the zine oxide were dissolved in 30 coc. of concentrated Hydrochloric acid, heated to dissolve all Zine oxide and allowed to cool to room temperature, lead chloride separating out as needle-like crystals. The solution was filtered ard hy@rogen sulphide vassed through the clear filtrate. A yellow flocculent predipitate of combined areenic and Germanium sulphides came down and was recovered by filtration on a Buechner funnel. This precipitate was then dissolved by heating in a relatively small amount of hydrochloric acid, nitric acid added to convert the arsenous sulphide to the non volatile arsenic state. The mixture was distilled in a current of carbon dioxide. Germanium chloride came over at about 120°C. and was reprecipitated from the acid solution as white Germanium Sulphide (GeS,) . Although the procedure developed by Clarke seemed much more applicable to large scale work than the distillation methods previously outlined, it had a serious drawback in the fact that it necessitated the handling “oF strong hydrochloric acid. He substituted sulphuric acid of the same concentration, which gave equally good results. The use of sulphuric acid instead of hydrochloric was advantageous from a standpoint of cost as well as relative corrosive qualities of the two acids. The remainder of this paper will be taken up in a presentation of the work done in the development of Clarks procedure to @ semi=works scale, comprising both laboratory and semi-works experiments. Laboratory Developments. (a) Determination of acid concentration It was first necessary to determine the minimum quantities of 60°Be. sulphuric acid and water required for a given amount of oxide, considering both solution of the oxide and precipitation of the dissolved Germanium. ds the oxide was readily soluble in acid, the amount of acid was determined by the requirements for the precipitation of Germanium. Accordingly, 10 gr. charges of the oxide were dissolved in varying quantities of 60°Be. acid,mixed with I00 c.c. of water, agitated to insure complete solution, the precipitated lead sulphate allowed to settle and the solution filtered. After cooling, hydrogen sulphide was passed through the filtrate until precipitation was complete, a condition that was indicated by the absence of further precipitation when gas was passed through the filtrate from the original precipitation, or until there was indieation that precipitation would not be complete. The results showed that the most economicai mixture for 5. ‘complete precipitation per 10 gr. of oxide was 25 c.c. of 60°Re. sulphuric acid and 100 c.c. water. Smaller concentrations of acid yielded a precipitate of the combined sulphides that was more or less colloidal in structure, making filtration and recovery difficult if not impossible. (b) Heat effects and their relation to Precipitation = ilethods of Precipitation . As the addition of acid to the oxide and water caused a very appreciable temperature rise , approximately 35°C, and , as noted by Clarke , the solubility of Germanium Sulphide increases very rapidly with increased temperature, it was necessary to determine the maximum temperature at which precipitation would take place. The relation of this date to large. scale operation is obvious, as precipitation at higher temperatures would eliminate the necessity of cooling after the charge had been agitated with acid. @o obtain this date , as well as information as to methods of precipitation, 100 gr. of the oxide were placed in a 2 liter battery jar, 1000 c.c. water and 250 cece. of 60°Be. sulphuric acid slowly added, the mixture being agitated by means of a motor driven stirrer. After I hour , agitation was stopped and the solution allowed to stand. The lead sulphate settled out rapidly, decantation yielding a clear liquid after four hours. The clear liquid was transferred to a & liter wide mouth bottle , fitted with a mechanical stirring device that is best described by reference to figure (I). : A vertical shaft, fitted with a pulley (g) passes a gure | ba. 6. ' through a mereury filled, gas tightbearing (a). At. the end of this rotating shaft is connected a two armed . stirrer made of glass tubing with openings at (b) ana (a), but sealed at (co). The liquid level is slightly above the eross arms (h). On being rotated , liqiid tat is in the lower part of the stirring arms is thrown outward by centrifugal force, causing a flow of liquid upward and out against the walls of the container at (a), at the same time pulling liquid in at (b). This causes a circulation of liguid as well as exposure of a large wetted surface. Hydrogen sulphide ges from a Kipp generator, passes in at (e), air first being expelled through (f). This apparatus prooved to be very well adapted to precipitations of this nature. It eliminated the necessity of a hood to carry away hydrogen sulphide , since the total amount of gas utilized consisted only of that required for precipitation and to saturate the liquid. A I5 e.c. sample (called rl) of the clear filtrate was taken before precipitation in the 2 liter jar was started, hydrogen sulphide passed through it until | precipitation was complete and the liquid saturated with gas. This was filtered and 10e.c. of the Ziltrate titrated with KilnO, solution. At different stages in the precipitation in the 2 liter jar , I5 e.c. samples were taken, filtered , and 10c.c. portions titrated with KMnOg. This afforded a means of observing the rate at which Saturetion was taking place, the extent of precipitation at different time intervals and the extent Ve ‘ of saturation when precipitation was complete. ihe ratio of the amount of KlinOg reduced by 10 c.c. of saturated liquid to that reduced by any given sample indicated the percentage saturation existing et that time. The extent of precipitation was vispally estimated and was accordingly only approximate. -<-== In this manner a number of observations were made with regard to the time required, saturation effects and the rate and efficiency of stirring and agitation , as related to temperature . The results of these runs are tabulated below , and graphically represented on page "a. (A) Precinitation at 20°C. Semple Time of contact c¢.c.KMn04 Jo Yo with Hes . used pption. saturation I. 45 min. 40.70 100 LOO 2. 15 6.95 60. 17 Se 30 15.80 95 34 4. 45 17.90 LOO 44 De 60 38.60 Loo 94 Remarks: Precipitation complete after 45 min. agitation. Solution 44% satureted . (B) Precipitation at 35°C. Sample Time of contact ¢.c.KMn0, Je 40 with HoS used pption. saturation. I. 45 min. 36.00 100 100 2. 30 8.60 24 Be 45 | 12.00 38 Ae 60 . I9.00 50 5 75 18.90 _ 60 Va. Ho [00 zoe Remarks: Precipitation complete after I hr. agitation. | Solution 50% saturated . (CG) Precipitation at 45°C. Sample ime. of contact c.c.Kiin0, yp with Hos used pption. saturation I. 45 min. 56-50 L00 TOO Re 50 9-40 26 . Be 45 9.90 27 4. 60 10.00 2764 5e 75 10.70 29 6. 105 20.10 55 Remarks: Precipitation was not complete at the end of Ihr. I5 min. agitation . Saturathon was 55% . The results of these runs were interpreted as indicating the fact that for satisfactory precipitation the temperature should be as much under 259C. as possible. Above this temperature proper coagulation was not obtained. At lower temperatures the precipitate settled out repidly, leaving a clear liquid that could be decanted off , and that gave no further evidence of precipitation when subjected to contact with hydrogen sulphide. Another interesting fact was that the liquid did not have to be saturated.In fact , less than 50% Saturation was sufficient for complete precipitation. (c) Determination of Yield . To determine the yield of the process as outlined , 100 gr. of the oxide were agitated with IOO0C o.ce Of water and 250ce.c. 60°Be. sulphuric acid, Ge .ags previously described. The clear filtrate was transferred to the precipitating jar and agitated with the centrifugal device until precipitation was complete. When the precipitate of the combined sulphides had settled, the clear liquid was decanted off and the precipitate collected on a Buechner funnel. The precipitate was washed free from hydrogen sulphide with dilute acid ané dried in an oven at II5°0C. The filter cake was removed from the paper and weighed. As this weight representeéd the combined germanium and arsenic sulphide obtained from a 100 gr. sample , approximately one tenth of this precipitate was weighed out and a quantitative analysis made to determine the percentage of Germanium sulphide in the combined ‘precipitate, the quantitative procedure conforming to that previously used in the analysis of a IO gr. charge of the original zinc oxide. The procedure , as used by Clarke, is as follows := 50 c.c. of 68% HBr is added to the weished sample in a 100 a,c. distilling flask. Distillation is made through a condenser and adapter into a 500 c.c. conical flask containing 10 c.c. of water into which the adapter igs dipping. Distillation is continwed until the residue is neerly solid and has a volume of I0@Ib ec.c. The condenser is washed through with a minimum quantity of fuming nitric acid , and fuming nitric acid added to the distillate slowly until all HBr is converted to Br. . This is heated on a water bath until all Br. is expelled and then boiled to a small volume, avoiding the ceparetion LQ. of germanium and arsenic as oxides in the strong nitric acid solution. The Liquid is transferred to a platinum erucible and the evaporation finished on a water bath. Im¥2 coc. of hydrofluoric acid are added, the oxides forming @ clear slightly colored solution which is evaporated to a syrupy consistency. I0-I5 drops of hydrofluoric acid are added and about 25 drops of saturated potassium fluoride solution and 2=3 c.c. 95% alcohol to make precipitation complete. Filtration is made on a filter paper pulp in a platinum .Gooch, washed with 95% alcohol until free from potassium salts , and the crucible dried to constant weight at I25°C. Increase in weight represents KeGeFg . Three such runs were made , the results obtained being as follwe :- Ut. of combined Amt. taken Wt. Equivalent % Ge ASoS; & Gedo for analysis KoGeFg amt. GeOp Extr'n. 7293 er. -0893. .0563 -O0222 74.0 15956 1061 .0886 .0349 | 80.0 «7502 20712 «0430 20170 71.0 The fact that a more nearly quantitative recovery was not realized may be attributed to several possi-# bilities, the most probable being failure to make a clean recovery of the combined precipitate. As this loss would necessarily be magnified in small acale work it was not considered improbable that the same procedure would give an extrection of over ninety percent when applied on a semieworks sesle. Other losses, such as partial colloidal suspension of the precipitste and incomplete precipitation if. . would no doubt make up the remaining loss. | (a) Re-utilization of Acid . From an economic standpoint it was very important to determine the extent to which the sulphuric acid in the process could be used before if had to be removed from the process altogether, and replaced by a fresh charge. The filtrete resulting when the arsenic: and germanium sulphides had been removed. differed from the original solution of acid in these two respects: decreased acid concentration and the presence of a lerge amount of dissolved zine sulphate . To put this liquid back into the processs to dissolve more zinc oxide, germanium and arsenic , the acid concentration could be brought back to its original value by addition of concentrated acid. Assuming that the presence of dissolved zine sulphete would not interfere with precipi- tation with hydrogen sulphide , the number of times the acid could utilized would therefor depend on the solubility of zinc sulphate in the sulphuric acid. A run was made in which the filtrate, after the removal of the combined sulphides, was used to treat a second charge of oxide, enough acid being adted to bring the acid concentration up to its original value. Precipi~ tation was satisfactory in every respect , but at the end of this run the filtrate was practically saturated with zine sulphate , the crystals becoming evident when the temperature was lowered to about 25°C. This result was compatible with data obtained on the solubility of Iz. _ gine sulphate in sulphuric acid and definitely established the fact that at the end of the secénd run the acid would have to be removed from the process, neutralized, and the zinc sulphate recovered. Semi-works ‘Development . It was decided to use, in the large scale runs, a charge of 50 lbs. of zinc oxide. Accordingly, a 100 gal. redwood tank, the dimensions of which are shown in figure (2) was used, having been given two coats of Biturin Asphalt paint. Mechanical agitation was furnished by means of a wooden stirrer shown in the drawing, rotated at approximstely 40 r.p.m. 50 lbs. of the oxide were weighed into the tank, followed by 450 lbs. of water. With the mixture being agitated 220 Lbs. of concentrated sulphuric acid (spegr. 1.834) were slowly added and agitation continued for two hours. During this step the temperature went to 60°C. The solution was allowed to stand twelve hours eat the end of which time the lead sulphate had completely settled out, leaving a clear liquid. During this time the temperature had dropped to 32°C. ‘he liquid was transferred to a second 100 gal. tank by means of a vertical, steam driven, Duriron pump. It was possible to transfer approximately ninety five percent of the liquid before it began to come over cloudy, due to agitation of the lead sulphate. Pumping was stopped at this point and the remaining liyuid transferred, after being allowed to settle a second time. The lead sulphate was transferred to a small crock for future recovery. Iéa Precipitoting ‘Tonk semi-works scale . "diam. iron pipe ‘diam glass tubin -? pip _t QIASs to 9 qa +S = eee i “angle tron | 2 ttoss brace | | Foes’ T, = : - | ; { tt quid level u $48 sth eh | { x4” nipple J if < 7 > wooden caller $xS pine Floovieg Stuffing Box Figure 2. 2b. _H,S Generator Id. ‘the tank into vhich the filtrate was pumped was fitted with a gas tight top the construction of which is shown in figure (o) . This top contained a stuffing bos, through which ran the vertical section of the stirring device, which is also best described by reference to the drawing, said devite being made of $" black iron pipe , coated inside and out with Asphalt paint. The stuffing box , or bearing, consisted of a snugly fitting wooden collar, fitting into a counter- sunk aperture in the tank top, and held firmly against @ packing consisting of gasket rubber, by means of two plates and bolts , as indicated. The vertical section of the stirrer was attached to the rotating shaft end rotated at approximately 125 r.p,m. This speed was sufficent to throw liquid against the rim of the tank, allowing the liquid to run down the inner walls. Hydrogen sulphide gas was furnished by a generator consisting of three two liter jars, connected as shown in figure (23) . (a) contained a layer of broken porcelain on top of which was pvlaced iron sulphide. Bothe (b) and (c) contained dilute sulphuric acid, the purpose of (¢c) being to collect sediment and prevent clogging of the generator jar (a) . Gas was passed into the closed tank at (A), air being first displaced through (B). (B) was then closed and agitation started, a positive pressure being maintained throughout the ruh. At intervals a samole was removed from the tank through 4. ' the opening (B) by means of a suction line, and the condition of the Liquid noted , with regard to completeness of precipitation. At the en# of I¢ hrs. precipitation was complete , as indicated by rapid settling of the precipitate and no further precipitation when the filtrate was subjected to passage of a free -gurrent of hydrogen sulphide. The liquid was allowed to stand twelve hours. Filtration was then made by means of a Duriron pump and & canvas filter leaf, built up on a frame of $+" lead pipe. It was not intended to build up a cake on the leaf, but to remove the large part of the liquid. When this had been accomplished , the precipitate , held in Suspension in a small amount of acid was transferred to a crock, and after being allowed to settle , more of the clear liquid siphoned off. The combined precipitate of areenic and germanium stlphides was finally recovered on a large Buechner funnel. A second run was made, 50 lbs. of zine oxide being added to the filtrate from the first run. 68 lbs. of acid were added to bring the acid concentration up to its original galue. The only difference in the two runs lay in the fact that after the solution had been subjected to precipitation and allowed to stand, zine Sulphate began to crystallize out. This in no way interfered with results, but made reeovery of the combined sulphides more difficult. I56 Separation of Germanium from Arsenic . it was originally planned to separate the Germanium from the arsenic , in the combined precipitate, by - distillation , regardless of the fact that it would necessarily be a slow process. Clarke had found, however, that the relative solubilities of arsenic and germanium sulphides , in acid , varied considerably with the temperature. To such an extent ig fact, that when the combined precipitate from to ere of oxide in 25 ec.c. of I2 N acid was heated to between 80-95°9C. and filtered, a quantitative separation was made, germanium sulphide being completely dissolved and no arsenic whatever being carried through. This method of separation was attempted on a large scale an the following manner :- A large evaporating dish ( 45 om diam.) was filled with Ic N acid and the combined precipitate added, being stifred mechanically. The temperature was maintained at 95°C. and stirring continued for I hr. The hot solution was filtered through a suction filter, with asbestos as the filtering medium. The precipitate was added to a feesh charge of acid and the process repeated, the filtrates from all the extractions being combined. After four extractions the combined filtrates were saturated with hydrogen sulphide at 25°C, <A white precipitate characteristic of germanium sulphide came down , but on standing became slightly discolored, indicating that separation had not been complete.1® was further evident , from the size of the precipitate, that I6. this method was not adapted to separation, due to the extremely small amount of Germanium that was recovered from each extraction. Limited time prevented the separation by distillation, work on the problem being stopped at this point. The writer acknowledges his indebtedness to Dr.eWm. N. Lacey, under whose supervision this work was carried out, for many helpful suggeetions and personal assistance. Summary. I. Large laboratory Scale and semieworks scale investigations have been carried on toward the develop= ment of 4 commercial process for the extraction of Germanium from crude zinc oxide. Re The precivitation of arsenic and germanium by hydrogen sulphide from sulphuric acid solution offers a satisfactory method of concentrating a small amount of Germanium present, so that its recovery may be carried out in small scale equipment. Se & very satisfactory semi-works scale method was developed, for saturating a liquid with a gas with only small loss of the latter. This might proave generally applicable where noxious gases are being handled in large scale experimental work. California Institute of Technology Pasadena, California . 1922