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ACKNOWLEDGMENT Most of the hydrocarbons investigated in this work were synthesized by P. L. Cramer and F. K. Signaigo in these laboratories. Compounds obtainable commercially were redistilled just prior to use in the engine. The samples of 2,2,4-trimethyl-3-pentene and 2,2,4-trimethyl-4-pentenewere furnished by F. C. Whitmore and M. R. Fenske of Pennsylvania State College.
LITERATURE CITED (1) Alden, Natl. Petroleum News, 24, No. 3, 32 (1932). (2) Campbell, Lovell, and Boyd, J . Soc. Automotive Eng., 26, 163 (1930).
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(3) Lovell, Campbell, and Boyd, IND. ENG.CHEM.,23, 26 (1931). (4) Ibid., 23,555 (1931). (5) Ibid., 25, 1107 (1933). (6) Ibid., 26,475 (1934). (7) Neptune and Trimble, Oil dl- Gus J.,32,No. 51,44 (1934). (8) Ricardo, Automotive Eng., 11, 92 (1921). (9) Ricardo and Thornycroft, Trans. World Power Conference,3,674 (1928). (IO) Thornycroft and Ferguson, J. Inst. Petroleum Tech., 18, 329 (1932). (11) Veal, Best, Campbell, and Holaday, S. A . E. Journal, 32, 105 (1933). RECEIVBD July 16, 1934. Presented before the Division of Petroleum Chemistry a t the 88th Meeting of the -4merican Chemical Society, Cleveland, Ohio, September 10 to 14, 1934.
Utilization of Alunite through Alkali Fusion E. 0. HUFFMAN . ~ N DF. K. CAMERON, University of North Carolina, Chapel Hill, N. C.
F
OR c e n t u r i e s a l u n i t e , KzS04. illz(SO4)3.A1203 .6H20, has been utilized as a raw material for the pro-
The values in alunite can be rendered watersoluble by fusion with sodium or potassium hydroxide, and the alkali in the water solution can be converted to the corresponding carbonates with precipitation of sulfates by treating the solution with barium carbonate and carbon dioxide under pressure. The values in alunite can also be rendered water-soluble by fusion with sodium sulfide. Cheap sodium sulfate and coal breeze, obtainable in the same area with the alunite and heated with it, accomplish the fusion. Partial control of the sulfates is obtained through the time and temperature of fusion. Leachings from the sulfide roasts form a n alkaline solution containing all the values: from it a mobile scheme of recovery may be planned which is adjustable to market conditions.
duction of alum and potassium sulfate. Roman alum was made from it and was prized because of its relative purity, and because it could be recognized readily by the cubical form of its crystals (ordinary alum is obtained in octohedral crystals) and by the inclusion of small red specks of ferric oxide. Crystallization from alkaline solution and mixing of powdered brick dust led to imitation in later times. The most famous of the older sources a t T o l f a , near Civita Vecchia, Italy, has been described many times. Deposits h a v e bee’n f o u n d i n U t a h , Nevada, California, and Vancouver Island; only the one in Utah has had any development approaching commercial importance. Marysvale, now a distributing point for a large area of southern Utah, was once an active gold-mining camp because of its proximity to the once famous Annie Laurie Mine, and it has some importance today because of the Deer Trail Mine. North and south of the town rather intensive prospecting has located a number of deposits of alunite. The first discovered and by far the most important is a rein or series of veins starting at an elevation of over 11,000 feet near the peak of one of the Tushar Mountains and traced t o the Deer Trail Mine a few hundred feet above the valley floor Yhich has an elevation of somewhat over 5000 feet. This deposit was described first by Butler and Gale ( I ) who estimated that it contained upward of 3,000,000 tons. It probably contains much more than this. There has been a considerable exploitation of these deposits, mainly by the principal ownersthe Florence Mining and Milling Company, the Swift Fertilizer Works, and the E. S. Mining, Milling and Smelting Company. The latter deposits furnished a large tonnage during the World War to the Mineral Products Corporation which then controlled it. They built a plant a t Alunite, about 9 miles south of Marysvale. The ore was carted down the
mountain, crushed and ground (4, and roasted in a rotary kiln a t a temperature sufficiently h i g h t o e l i m i n a t e all of the sulfur combined with alumina. The escaping oxides of sulfur were not r e c o v e r e d , and the location of the plant prevented t h e m f r o m being a p u b l i c nuisance. The roasted ore was leached, the l e a c h i n g s were c o n c e n t r a t e d by evaporation, and a high-grade p o t a s s i u m sulfate w a s r e c o v e r e d . The leached residue was discarded, p r o b a b l y because t h e high temperature of roasting made the alumina intractable for all available treatments. The F l o r e n c e M i n i n g and Milling Company, in cobperation with the Caroleigh C h e m i c a l Company of Raleigh, N. C., ground and roasted alunite a t a plant about 4 miles south of Marysvale, the product being shipped east to be incorporated with mixed fertilizers as a source of potash. ilt Sigurd, about 55 miles north of Marysvale, some old beehive roasters which had formerly been used for roasting gypsum were employed in a process devised by Cameron ( 2 ) ; the roasting took place at about 500’ C. The roasted lumps rrere crushed and leached, and alum was recovered. The alum was then roasted or “burnt,” and potassium sulfate was recovered by leaching and evaporation, together with a quite pure alumina. Disagreements among the operators led t o abandonment of the process, and the remaining operator substituted the Morgan process for roasting a mixture of alunite and limestone. Leaching and evaporating gave an enormous yield of beautiful white crystals of syngenite, K2S0&aSO4.Hz0. Two carloads were shipped to eastern fertilizer manufacturers on the assumption that the product was pure potassium sulfate; when analysis led to recognition of the true nature of the substance, the operator fled and operations were abandoned. Shortly afterwards the American Smelting and Refining Company built and operated a plant at Murray, Utah, using a process designed by Cameron and Cullen (S), for roasting ground alunite mixed with sulfuric acid. Leaching
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INDUSTRIAL AND ENGINEERING CHEMISTRY
the melt, a solution was obtained of aluminum-potassium sulfate and aluminum sulfate. Ammonia liquor from the Salt Lake City gas works was used to convert the aluminum sulfate to ammonia alums, and about two hundred carload shipments of the alums were marketed. These activities stopped with the end of the war. The rapid fall in price of potash salts from the Korth German and Alsatian deposits, the fact that alunite contains but 37* per cent of alumina against the 63 per cent in bauxite imported from South America, and the relatively bad transportation position of Utah with relation to markets mere determining factors.
EXPERIMENTAL PROCEDURE Many attempts have been made to find a method for using alunite as a raw material in the chemical industry. A recent discussion and summary by Thoenen (6) makes i t unnecessary to repeat details here. A number of these proposed procedures have been reexamined with a view to their commercial practicability and have led to a consideration of two possibilities which appear to be novel and of an importance justifying publication. The fundamental basis of these operations is to sinter or fuse pulverized alunite with an alkali to render all the alumina water-soluble, as well as the potential potassium sulfate it may contain. Most effective t o this end is sodium (or potassium) hydroxide. But as shown by Table I, it is necessary to use an excess of the hydroxide to render all the alumina water-soluble. A graph of these results is a smooth curve apparently asymptotic, which shows but little advantage in using more than 1.033 grams of potassium hydroxide per gram of alunite. RECOVERY OF ALIJMIXA BY ROASTING ALUNITEWITH POTASSIUM HYDROXIDE
TABLEI.
W T . KOH
WT.ALUNITE 1.0373
1.0400 1.1002 1.2023 1.4905
ALGMINA OBTAINIOD
RECOVERY
%
70
31.00 31.32 33 I42 36.05 38.14
81.35 82.20 87.48 94.50 100.00
TABLE11. EFFECTOF INCREASE I N P R E S S U R E O N CONVERSION OF POTASSICM SULFATE TO POTASSIUM C A R B O S A T E B Y C A R B O N DIOXIDE IN PRESENCE OF BARIUM CARBONATE PRESSURE Lb./so. in. ( k g . / s o . em.) 60 75
so
85 90 100 125
Kd207 OBTAINED F R O M TOTAL
R PRESENT lo 78.68 80.85 85.58 90.21 93.31
CONVERSION %
64.18 $7.16 (4.01 80.23 84.47 91.49 97.30 97.36
This process would be commercially feasible if a practicable method could be found for recovering the alkali hydroxide. It is dl known that treatment of the solution with calcium hydroxide would not yield a complete conversion of the sodium or potassium salts to the corresponding hydroxides. A solution obtained by leaching a melt of alunite and potassium hydroxide was saturated with carbon dioxide and the precipitated alumina separated by filtration. Milk of lime added to the filtrate precipitated all the carbonate but only a little of the sulfate ion. Several repetitions gave recoveries of 52 to 67 or an average of 57.01 per cent recovery of potassium hydroxide which had been added to the alunite. It was then attempted to recover the potassium as carbonate. Pulverulent calcium carbonate was added to the mother liquor in a compression chamber, and carbon dioxide
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was passed through the suspension a t pressures of 100 to 125 pounds per square inch (7.0 to 8.8 kg. per sq. cm.). The suspension was agitated by a stirrer formed by a soft iron wire sealed in a glass tube and agitated by an electric solenoid outside the compression chamber (Figure 1). It was assumed that the calcium carbonate would be converted to the bicarbonate, and, under the conditions of the experiment, that calcium sulfate would be the least soluble solid possible and a complete precipitation of sulfate would ensue. The a n t i c i p a t e d reaction took [ (-4Jb-4 place to a very small extent & only. Substituting b a r i u m carbonate for calcium carb on a t e , the process proved successful, as shown in Table 11. The results obtained at a p r e s s u r e of 125 pounds p e r s q u a r e inch show that practically all the sulfate ion was precipitated w i t h t h e barium and practically all the potassium in the mother l i q u o r was recoverable as carbonate. Barium carbonate is obtainable in quantity and a t a price n o h i g h e r than the selling value of the barium sulfate formed, which might be m a r k e t e d a s such or reduced t o barium sulfide for lithopone or insecticides, or converted FIGURE 1. C O M P R E S S I O N CHAMBERF O R TREATING to the carbonate. A posS O L U T I O NOF S ALKALINE sible objection to the process SULFATES WITH BARIUhl is that the r e l a t i v e l y h i g h CARBONATE A N D CARBON p r i c e s of t h e barium carDIOXIDE bonate ($55 to $60 per ton) 1. Stirrer 2 . Three-way stopcock require a considerable capital 5. Compression chamber 6. Rubber platform p e r m a n e n t l y involved in oDerations and subiect to loss Gy leakage or accident. Moreover, the market for barium products is neither large nor very stable. Attempts to improve the process by substituting potassium carbonate for potassium hydroxide in fluxing the alunite met partial success only. Much more heat is required and the recoveries of alumina are seldom as high, so that a new procedure was sought. Along the shore and under the bottom of Great Salt T,ake are extensive layers of Glauber’s salt. This is easily raised by steam shovel and melts in its own Jvater of crystallization or with very little added water. Adhering sand sinks, and sodium chloride floats and can be skimmed off. ilfter decanting and cooling the liquid, a very pure sodium sulfate is obtained. Since the lake waters are saturated with this salt, large quantities separate in cold weather and are blown ashore to form windrows nThich are easily gathered; there is also a large production of the salt, mainly waste, in the operation of the Inland Crystal Salt Company. It is obtainable very cheaply, since there is no market for it owing t o prohibitive shipping costs. Powdered coal and coke breeze are also obtainable a t nominal figures. Hence, sodium sulfide can be produced for a few dollars per ton. As a flux it might be expected t o act similarly to sodium hydroxide. A melt of alunite, with rather more than the theoretical quantity of pure sodium sulfide, when leached showed 36.56 per cent soluble alumina or a recovery of 96.15 per cent. A series of experiments was made by roasting a mixture of alunite ground to pass a 40-mesh sieve, powdered coal, and
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iron cxint~~iiiers for tire roastiiig. Several roasts carried a iiickcl erucible I~adlydamaged tire crilcible. It may well prore advantngeoiis in a 1:wge-scale opcration to carry tho fitsiori t o a triie inelt wliich caii be tiiyiied from the coiitniner and thus facilitate a eontinuoils rstlier tiinn a hatch operation. The mother liquor or leacliings of t l i c melt contain in solutiuii sodium aluininate, potassium aliiininate, sodium hydroxide, piitnssimil hydroxide, and relatively small projrort,ions of nnlfates. The alumina is ren:\iiy ;aturatiiig the solution with carbon dioxide. 1311 pcrinits of t i mobilo plaii of recovery adspt:rlilo to market cmdiliow and need.: i i o further discitision licre. l'lic dunite used in tli perceutaige cuqmiticxis: silica, 0.135; aluiniiia, 35.1; .iiiin iisiile, 10.5; sodioin d e , 0.33; ferric oxide, FiirnislieJ by ,I. A. I'itzwater (khti), 1 3 . 2 I t 1 p t r i c k of tlic Fli~renccMining a Milling Ginpany, aiid is rcixcicntritivc oS the ore hidy friiin that c u n p m y ' s morkings. The :mtlioss wish to ncknowlcdgc X r . Fitzptrick's courtesy. iisc
