Nov., 1 9 1 2
T H E JOL+R+YA4L OF I S D G S T R I A L A.YD E L Y G I S E E R I ~ Y GC H E - V I I S T R Y .
The material which was later made continuously according t o the process described above carries 4 . 5 per cent. of water-soluble K,O in the form of 7 . 1 2 per cent. potassium chloride and in addition to this the material carries only I . 1 2 per cent. K,O insoluble in water. I t is well known that a 2 per cent. citric acid solution will extract, when used according to the Wagner method, somewhat more K,O than can be made directly water-soluble. This fact is of considerable interest when the product is to be used directly as a potash fertilizer. c 0N c L L- s I O s . It is believed that under better conditions of heat treatment which can be obtained with longer kilns and with a somewhat different arrangement of the combustion chamber, slightly better yields than those reported can be obtained. It should be remembered t h a t the kiln used in these experimental trials was originally designed for burning cement, but this type of kiln has long been superseded by improved forms. I n order to get the proper heat treatment in the middle of the kiln to complete the reaction, i t was necessary t o have the upper part too hot. This condition mill not maintain in a properly designed kiln. It is also believed that the use of oil as fuel would have allowed an easier regulation of the heat treatment b u t the trials so far undertaken have been made under conditions which were found available a t the time. The subject of the costs of this process and of the product cannot be gone into in detail at this time b u t a few general statements may be made. The production of water-soluble potash in feldspathic rock is essentially a low-grade proposition, and the commercial success of such a process depends upon the low cost of the various operations. The manufacture of a straight potash fertilizer containing as valuable ingredients only potash and lime, must be carried out on a very large scale and by the most modern methods of continuous operation. With regard to the clumping process. the trials have shown that this operation can be practically carried out as a continuous process and a t a n exceedingly low charge per ton of product. The process may be directly compared with that of the manufacture of Portland cement. It is a little easier t o grind feldspar and lime than the shales and limestones used in cement manufacture. Drying will cost no more. Chemical control of the raw mixes will not be more expensive and perhaps much less. Clumping, as has been shown, adds a very small charge to the expense of treatment. The cost of furnacing the feldspar mix will be less than similar charges in the cement industry, as the temperatures required are much lower and less coal is consumed. The product from the potash kiln is comparatively soft and pulverizes easily in hammer mills, while the charges on the cement industry for grinding clinker is a n important item. Again, the softer potash product merely requires to be ground fine enough for use as a fertilizer, whereas cement clinker must be ground very fine and costs rise rapidly with increas-
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ing fineness. Repair bills in the case of feldspar treatment should be much smaller than in cement manufacture. The charge for raw materials is somewhat larger than in the case of cement, but this is more than met b y the smaller costs of operation. The potash fertilizer a s now produced should be the equal in fertilizing value of the ordinary grades of hardwood ashes. The product carries practically the same content of water-soluble potash and a considerable percentage of free lime. There is every reason t o believe that if the process becomes a n industry the yields of water-soluble potash can be considerably improved. The material yielded is not a fused product, i t is friable as an ash and i t has the physical texture to make i t a valuable aid to soil structure. The success of the product must. of course, depend upon the results obtained under test conditions in its experimental use as a fertilizer. If results are obtained which are as good or better than those which usually attend the proper use of highgrade wood ashes, i t is believed that there should be no reason why this product cannot be successfully produced and introduced, especially in those parts of the country where potash feldspars, fuel and shipping facilities are available. The results obtained on a number of experimental trials on a mill scale of operation show that i t is possible t o economically manufacture a potash fertilizer containing free lime from feldspar and for a sufficiently low cost to make worthy of consideration a n industry based upon the method described. RESEARCH, U’ASHINGTON, D. C.
INSTITUTE O F ISDUSTRIAL
POTASH, SILICA AND ALUMINA FROM FELDSPAR.’ B y EDWARD HART.
I n a study of the commercial utilization of feldspar which I undertook several years ago, i t soon became evident that the potash alone would not pay the cost of extraction. This is the cause of the commercial failure of all the methods heretofore proposed. It is necessary, therefore, to separate and put into marketable form the other constituents-silica and alumina-if our method is to be successful. With this purpose in view I have finally worked out the following process which gives good prospect of commercial success : The feldspar chosen should contain not much less than 1 2 per cent. potash. Spar of this quality can be obtained in quantity, but one of the pitfalls inventors must avoid is the expectation of getting spar containing the theoretical 1 6 . 9 per cent. of potash. The spar mixed with the proper amount of potassium sulfate and carbon is fused. The carbon added is so regulated that the resulting slag contains a considerable proportion of sulfids. This has the double advantage of saving a part of the sulfur, disengaged as hydrogen sulfid on dissolving in acids, which aids also in the complete decomposition by breaking apart the particles as i t is given off. Experiments show that if a colorless slag is obtained of even higher alkali content 1 Paper presented a t t h e Eighth International Congress of Applied Chemistry, Sei5 I’ork. September, 1912.
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T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERIATG C H E M I S T R Y .
i t is much less easily decomposed b y sulfuric acid. The slag so obtained must be very finely pulverized and treated in closed vessels with dilute sulfuric acid leaving behind a very pure silica which needs only washing and ignition t o yield a marketable product fitted for the potter’s use or for the manufacture of sodium silicate. The solution contains potash alum and any small amounts of other metals such as iron, manganese and soda as sulfates. Lime is inadmissible, as the sulfate forms crusts on evaporating. The solution on cooling gives a t once crystals of alum, which washing with a little water and centrifuging renders marketable. Any iron present remains as ferrous sulfate in the mother liquor. Alum, however, is marketable only in limited quantity and must be, for the most part, converted into its constituents, aluminum and potassium sulfate. This is easily done b y adding to the solution in a closed vessel potassium sulfid in slight excess when aluminum hydroxid mixed with a little sulfur precipitates in a form easily washed. This is dissolved in hot sulfuric acid, run through a filter and allowed to solidify. The potassium sulfate is obtained by evaporation. Each ton of feldspar (12 per cent. K,O) should yield 444 lbs. K,SO,, 2040 lbs. commercial aluminum sulfate (18 per cent. A1,0,), and 1300 lbs. SiO,.
Nov., 1912
the potassium present therein. Since in such analyses any error is thrown upon the sodium, the presence of potassium therein would not be revealed unless tested for. The investigation has consisted in a study of representative specimens of rock salt from those places where the beds have been entered; of brines from salt wells; of brine from gas and oil wells; of brines from salt lakes and of salt crusts from salt playas and marshes, and of the mother liquors and other concentrates from the salt refineries of the states east of the Rocky Mountains and from the “salt gardens” of the Pacific Coast. GEO LO GI C.4 L CO N S I D E RAT1 0 NS
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Rock salt has been found in large masses in three regions in the United States: ( I ) underlying an area represented by central and western New York, northeastern Ohio and probably the entire lower peninsular of Michigan; ( 2 ) underlying the State of Kansas and extending thence into Oklahoma ; ( 3 ) in Louisiana and Texas. I n Virginia and in certain localities of the west i t is found in smaller local deposits, where, in the latter region, it has been deposited as the evaporation product of saline lakes. The salt beds penetrated in New York, Ohio and Michigan are probably continuous, as they occur in the Salina group of rocks of the Upper Silurian, and GAYLEYCHEMICALAND METALLURGICALLABORATORY, LAFAYBTTE COLLEGE, the enclosing strata of the beds in the various regions EASTON,PA. for the most part have been pretty thoroughly correlated. The Salina formation appears as a n outcrop COMPOSITION OF TAE SALINES OF THE UNITED STATES.’ in New York along a line extending east and west, and I . Rock Salt, Artificial Brines and Mother-liquors from Artificial lying a few miles south of Lake Ontario. Thence i t Brines. extends southward and dips t o the south, disappearing B y J. W. TWRRENTINE, with analyses by A. R. MERZ AND R. F. GAKDNER. beneath the mountains of western Pennsylvania. The Received August 7, 1912. This report on the composition of the salines of the formation as far south as Ithaca and Watkins in the United States will embrace the following chapters: State of New York is known to carry rock salt, though I, “Rock Salt, Artificial Brines and Mother Liquors it is barren of salt in Pennsylvania.1 The Salina rocks from Artificial Brines;” 11, Natural (Subterranean) extend westward into Ohio until the eastern slope of Brines and Mother Liquors from Natural Brines;” the Cincinnati axis is encountered. The rock salt 111, “Brines from the Ocean and Salt Lakes;” IV, strata disappear east of that region. To the north“The Utilization of the Salines of the United States west, the western shores of Lake Michigan mark the as a Source of Potassium Salts;” and V, “The Occur- limits of the Salina. To the north and northeast rence of Lithium, Rubidium and Caesium in the Salines their limits are undetermined. Salt is being obtained from this formation a t Goderich, in Ontario Province, of the United States.” The present investigation was undertaken as a part Canada. Two theories have been advanced t o account for of the general problem investigated by the Bureau of Soils of the United States Department of Agriculture, the formation of the rock salt of the Salina strata. namely, t o determine what sources of potassium salts These theories are a t variance in that one supposes a could be developed in the United States. The inti- marine origin and the other, a continental origin. mate association of sodium and potassium in nature; The former describes the Salina sea as a n arm of the in the feldspars and other of the older rocks; in the ocean, separated from the ocean by bar-reefs or flats brine of the ocean and of numerous saline lakes and over which great tidal waves flowed into the bay. in the beds of deposited salts underlying the Magde- As the period was one of great aridity, only salt water, burg-Halberstadt region of Germany, warranted the in the manner mentioned, entered the sea. Concenbelief that the two might be associated likewise in tration through evaporation continued t o saturation with respect t o sodium chloride, whereupon t h a t the rock salt and other salines of this country. But slight informatlon bearing on the problem was substance was deposited. Later, apparently, before at hand. While numerous analyses of salines are t o the concentration with respect to the other saline be found in the chemical literature, in most instances constituents of ocean water became great enough t o seemingly no attempt has been made t o determine cause their deposition, the period of aridity came t o Published with the permission of the Secretary of Agriculture.
1
Chamberlain and Salisbury, Geology 11. p. 389.
