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374
ZbHoffmann, Loc. cit. 27--Lebreton, LOC.cit. 28-Will, Be?., 18 (1885), 1311; 20 (1887), 294. 2P-Hilger, Ibid., 9 (18761, 26. 30-Kraemer, “Text on Pharmacognosy.” 31-Von Rijn, “Die Glykoside,” 1900. 32-LeLong, “Citrus in California,” 1900. 33-Will, THIS JOURNAL, 8 (1916), 78. 34--l’anret, Comgt. rend., 102 (1886). 518. dS-Tanret, Ibid., 102 (1886). 1518; also Rraemer, LOG.cit.
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J&Aaronsohn, World’s Production in Citrus Fruits,” Trans. from Jewish Agr. Exp. Sta., Palestine, Bull. 1 (1914), 7 . 37-Virgi1, Georg. book 11, vers. 1 2 6 . 38--Wallach, Liebig’s Annalen, 246, 251. 39-EhestBdt, Regt. of Shimmel & Co., April 1910, p. 164. 40-Wil1, Bev., 20 (1887), 1186. 41--Mullikan, “Identification of Pure Organic Compounds,” Vol. I. 42--Zelinsky, Be?., 30 (1897), 1541. u. s. DEPARTMENT OF AGRICULTURE WASHINGTON, D. C. ’ I
LABORATORY AND PLANT AN INEXPENSIVE ASH LEACHING PLANT By W. D. TURNER AND B. G. NICHOLS Received March 25, 1918
The industrial chemistry department of the Missouri School of Mines has erected a small plant for the leaching of wood ashes, and a t this time when the potash industry is receiving such frequent mention,l a brief description of this installation will be of some interest. The work was started for its pedagogic value but developed t o a point where it assumed small commercial dimensions. APPARATUS
To apply the countercurrent lixiviation principle vertical columns of buckets were arranged. A column was supported on two upright “two by fours,” I O f t . long and spaced 2 0 in. apart, fastened directly t o the floor at the base and braced t o the ceiling a t the top. At a point 30 in. above the floor and a t intervals of 16 in. above this, spikes were driven part way into these uprights and projected outward about a n inch t o serve as brackets to support cross-rods of a/,-in. sq. iron bars from which the buckets could be suspended. The leaching buckets consisted of ordinary 6o-lb. wooden lard tubs, in the bottom of which a dozen or more holes were bored. The original handles were removed from these tubs and were replaced by heavier iron loops bent from l/d-in. round iron rods and fastened to the buckets by driving the ends through holes drilled in the sides of the tubs and bending them up into place. For the water reservoir at the top a bucket was similarly prepared with only one hole in the bottom provided with a loose wooden plug by means of which the flow of water could be regulated. T o catch the liquor at the bottom a t u b without holes was used. The column thus consisted of a liquor receptacle standing on the floor, above this a series of 5 leaching buckets, and at the top a water reservoir. This column constituted a complete unit. The second unit was constructed beside the first, letting one “two by four” serve in both columns. The two units were identical except that all the bracket spikes in the second were four inches higher than in the first t o prevent interference in changing the ashes. The third column was again like the first, and so on. The liquor was causticized in an ordinary oak barrel into which a current of live steam could be conducted t o heat and stir the contents, and from which the clear liquor could be siphoned after the mud had settled. 1 THIS
JOURNAL, 10 (1918), 6 , 96, 106, 109, etc.
For concentrating the liquor a cast-iron, seamless steamjacketed kettle was used, though for an isolated installation both this and the causticizing operations could be carried out in open flame-fired kettles. The final evaporation or fusing of the potash was carried out in an ordinary caustic pot. OPERATION
At the start of operations the bottom of each leaching bucket was covered with about 3 in. of excelsior, which later packed down t o an inch, and over this was spread a layer of old toweling or other cloth. The buckets were then filled t o the top with ashes and were lifted into place in the columns by means of a small block and tackle which could be suspended from a hook in the ceiling in front of each column. Water was then filled into the reservoir and was allowed t o drip through the successive buckets until the ashes in all were saturated. A measured quantity of water, equivalent t o half the weight of the ashes in one bucket, was then placed in the reservoir and was allowed t o drip through the column, forcing out a n equivalent amount of liquor into the receptacle at the bottom. When the top bucket had ceased i o drip, i t was removed by means of the block and tackle and was dumped. The excelsior and cloth which came out with the spent cake were replaced, and the t u b was again filled with fresh ashes. Each of the remaining buckets was now raised successively t o the next higher bracket and the fresh ashes were placed a t the bottom. Water equivalent t o times the weight of the ashes was now placed in the reservoir and was allowed t o drip through. This was sufficient t o saturate the fresh ashes and force out about half their weight of liquor. This operation of renewing the ashes was then repeated as often as the reservoir could be emptied. The liquor from the leaching columns was placed in the causticizing barrel until this was about threefourths full. The calculated amount of lime was then added and the mixture boiled for about an hour by means of the live steam jet. It was then allowed t o cool and settle and the supernatant liquor was siphoned into the concentrating kettle. The lime mud at t h e bottom was then spread over the fresh ashes a t the bottom of the leaching columns, so t h a t any potash which i t still contained was leached out as i t passed up through ’ the successive steps t o the top. By this means the customary countercurrent lixiviation of the lime mud was obviated. The concentration of the liquor was continued until most of t h e sulfate which i t contained separated out
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as a granular deposit. The liquor was then drawn off into the caustic pot where it could be evaporated t o any desired concentration or could be fused if necessary.1 T o obtain a clean product without the necessity for calcination, the potash in a part of the liquor was converted entirely t o sulfate by neutralizing with commercial sulfuric acid. This operation was carried out in a n ordinary oak barrel arranged so t h a t acid could be siphoned into i t directly from a carboy. Before neutralizing, the leach liquor was concentrated until
DIAGRAM OF LEACHING COLUMN
solid carbonate began t o appear. I t was then drawn off into another container where i t was allowed t o settle and cool. The clear, saturated solution was then placed in the barrel and the acid allowed t o run in until neutral t o litmus. This caused a violent reaction and resulted in the precipitation of a large per cent of the potash in a clean, pure, finely divided crystalline mass. This was allowed t o settle, the supernatant liquor was returned t o the concentrating kettle, and the crystals dried in a centrifugal machine. 1
Martin, “Salt and Alkali Industry,” p. 45.
37s
By this means almost all of the organic matter was removed and the potassium sulfate obtained was nearly pure and colorless, the sodium remaining behind as carbonate in the concentrating kettle, and the organic matter remaining in the liquor. DATA A N D R E S U L T S
It was found from preliminary experiments t h a t the rate of flow through the ashes was dependent mainly on the area of the cross-section from which the liquor could drain, but was practically independent of the depth. The buckets which were used were 1 6 in. in diameter a t the top and 1 2 ‘ / ~ in. a t the bottom, and were 1 1 in. deep. These dimensions gave a n area of drain of about 490 sq. in. and a capacity of about 3 j lbs. of ashes when loosely packed. Through this body the necessary 7 gals. of water would percolate in about 4 hrs. or less under favorable conditions. It was thus practicable t o make three changes per day, making the total capacity of each column about 1 0 5 lbs. Since oak ashes average about 1 1 per cent potassium salts the yield from each column was about I O or 1 1 lbs. of potash salt per day. One man could change one column in about I O or 1 2 min., so t h a t he ought t o handle easily 4 columns per hr. or a total of a t least I 5 columns, allowing 4 hrs. between changes. A few average analyses will give a measure of the efficiency of the apparatus. Analysis of t h e ashes in the vicinity of t h e School of Mines shows about 4 . 2 5 per cent hydroxide, 4.50 per cent carbonate, 2.90 per cent sulfate and 0 . 0 2 per cent chloride. If all converted t o sulfate this will yield over 1 5 per cent; if causticized it will yield about 7.8 per cent hydroxide and 2.9 per cent sulfate. Tests on the liquor from the top bucket just before discarding i t showed: sulfates a mere trace and total alkali figured as potassium hydroxide 0.3 per cent. But this final liquor is saturated with calcium hydroxide, so t h a t the actual potassium hydroxide content is not 0.30 per cent but about 0 . 0 6 per cent t o 0.08 per cent. The percentage recovery is therefore 99 per cent or more of the available salt. For causticizing, a dilute solution of the material t o be treated is necessary, and it will be noted t h a t the solution as it drains from the bottom bucket is just about a t the right concentration. Analyses on this liquor show about 3.75 per cent sulfate, 5.50 per cent hydroxide, and 5 . 7 5 per cent carbonate. This will yield about a I O per cent solution of caustic potash when completely causticized, a strength which is recommended as most economical.’ For this conversion the liquor from one bucket will require (allowing a 50 per cent excess) about I lb. of quicklime. Thus the average amount of sludge t o be returned t o each bucket from the causticizing bairel will be less t h a n 2 lbs. and may be spread over the surface of the ashes without detriment. It is probable even t h a t this sludge converts some potassium carbonate t o hydroxide during the leaching process. Typical results may be tabulated as follows: 1
F. H.Thorp, “Outlines of Industrial Chemistry,” p .
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TABLEOF ANALYSES Leach After Final Final Ashes Liquor Causticizing Hydroxide Sulfate SUBSTANCE Per cent Per cent Per cent Per cent Fer cent Sulfate . . . . . . . . 2 . 9 0 3.36 3.14 Trace 99.05 Carbonate.. . . . . 4 . 5 0 5.22 0.25 4 Nil Hydroxide.. , . . , 4 . 2 5 4.95 8.56 96 Nil ...... ... Chloride. 0.02 0.02 .. I,EACH LIQUORFOR A TYPICAL RUN,JUST BEFORECHANGING THE TUBS Tub No.. . . . . . . . . . . . . . . . 1 2 3 4 5 Total alkali (as K2COs), percent 0.33 1.99 3.59 6.88 12.30 S O D I U MAND ~ POTASSIUM IN PRODUCT NanSO4 KZSO4 Moisture Per cent Per cent Per cent 1.6 97.4 1.0 I i Sodium by difference.
..
...............
S U MM A R Y
A small, inexpensive ash-leaching plant is described in which the principle of countercurrent lixiviation is applied, with certain resulting advantages: I-Minimum initial expense and low upkeep. 2-Low operating cost. The leach liquor requires no concentration before causticization and the caustic sludge requires no separate lixiviation. 3-High efficiency. Recovery is 99 per cent or better. 4-Rapid manipulation. Each column furnishes a spent charge and a unit of full-strength leach liquor every four hours. MISSOURISCHOOL OF MINES ROLLA,MISSOURI
ANTIMONY SULFIDE AS A CONSTITUENT IN MILITARY AND SPORTING ARMS PRIMERS' By ALLERTON S. C U S H M A N ~ Received March 29, 1918
Toward the end of the year 1916 and throughout 1917, the production of military ammunition for all arms began t o be tremendously speeded up in the United States. At the same time, the overseas commerce of the world was interfered with by trade conditions incident t o the war and shortage of ships. The result of this combination of circumstances produced a very unusual condition with regard t o the chemical constituents used the world over in the manufacture of military primers of all kinds. For years past tersulfide of antimony has been used in almost every type of primer and is considered a necessary ingredient thereof, although the percentage quantity used in various formulas varies within wide ranges. The principal sources of antimony tersulfide for this purpose are the crude stibnite ores which are found native in many parts of the world, including England, Canada: United States and Alaska. Nevertheless, the principal supply of tersulfide of antimony as far as the United States is concerned is from Japan and China and a t the present time principally from China. It is probable t h a t the segregation of this business into the hands of the nations of the Orient is largely due t o cheap labor, so t h a t if on account of any condition incident t o the war it became difficult or impossible t o import antimony sulfide from overseas, the result would be t h a t the price of the crude materials would advance. Native antimony sulfide could then be produced in sufficient 1
2
Published by permission of the Chief of Ordnance. Lieutenaht-Colonel, Ordnance Department, N. A .
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quantity and of a sufficiently satisfactory grade t o assure the country a n adequate native supply. Antimony occurs in nature chiefly as the tersulfide (Sb&) in the mineral stibnite and t o a smaller extent in combination with other metallic sulfides under a variety of names, such as bournonite, pyrargyrite, kermesite, etc. For the purpose of this paper, however, i t will be sufficient t o confine the discussion t o t h e consideration of the more or less pure stibnite ores t h a t occur in nature. A s these ores are rarely free from a siliceous gangue, it is necessary in the preparation of the material for use as a primer constituent t o melt or liquate the oreout of contact with the air. Stibnite, when pure, melts a t approximately j j o o C . In the process of melting, a certain amount of metallic antimony is separated from the melt and goes to the bottom, while, on the other hand, the siliceous gangue impurities rise t o the top. On cooling down the melt, therefore, the intermediate layer represents the liquated antimony sulfide which should be carefully separated from the other two layers and represents the raw material of the antimony sulfide used as a primer constituent. If during the process of melting down, the antimony sulfide comes into contact with oxygen of the air, i t is t o a greater or less extent oxidized and the material is not pure sulfide of antimony but contains an indefinite proportion of oxide, and possibly some in the form of oxysulfide intimately associated with the tersulfide which has not been oxidized or burned. The work of liquating t h e crude ores is principally done in China and Japan before the material is imported into the United States; with the result t h a t heretofore there has been b u t little control of this process and the antimony sulfide available in the open market has shown a wide variation in its chemical analysis and therefore in its quality. Textbook and periodical literature on the subject of specification of antimony sulfide as a constituent of primer mixtures is for the most part meager and often misleading and inaccurate, It is usually the custom t o direct t h a t the purity of the antimony sulfide in quektion shall be determined by analyzing the material for antimony by any of the well-known volumetric methods and then calculating the percentage of antimony t o the basis of the tersulfide (Sb&) which in a sample of pure stibnite should figure out very close t o 100 per cent. A number of chemists have become aware of the fact t h a t analyses and calculations made on this basis very frequently led t o results running over I O O per cent, which was assumed t o be due t o the fact t h a t some slight amount of free antimony accompanied the antimony sulfide. On the other hand, when calculations were made on the same basis of analyses and came out less t h a n I O O per cent, it was considered t h a t this showed an unsatisfactory grade of purity in the material. The fact t h a t the antimony determination is easily and quickly made, while the determination of sulfur in the material has been considered a difficult and unsatisfactory determination, has probably been the principal cause of this state of affairs.
