Nov., 1 9 1 2
T H E J O URA'AL OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y . EXTRACTION OF THORIA.' By
CHARLES
BASKERVILLE.
Thorium dioxide is obtained in the main from monazite sands, which in round' numbers may be said t o have this composition:
currents. The numerous experimental details' need not be recited. Suffice i t t o say t h a t a satisfactory charge may be with a sand of the approximate composition given above a s follows:
.............................. ...................... ........................................ ..................................
Monazite sand.. Carbon (petroleum coke). Lime Fluorspar..
Per cent.
P206(phosphates).. .......................... CezOa (earths) ............................... DizOa (earths) ............................... Si02 (silicates). .............................. Tho2 (silicates and perhaps phosphates).
........
29 31 31 1S O 6.5
I n the winnowing it is necessary to g l t rid of the phosphorus compounds a s they materially interfere with the efficiency of the thoria when used for mantles. This is usually accomplished by converting the earths into insoluble oxalates after solution of the sand. Other methods have been proposed and some are now used commercially for avoiding this by fusion with alkaline carbonates and leaching the phosphates out with water, dissolving the residue in suitable acids, and then making the separation of the earths. TroostZ prepared thorium carbide (ThC,) by heating the oxide with carbon. Moissan and Etards made elaborate studies on the formation and properties of thorium carbide. Muthmann, Hofer and Weiss4 fused monazite sand with carbon and dissolved the carbides a n d phosphides obtained in hydrochloric acid. Wherea s the objectionable phosphoric compounds are removed in this manner, other practical difficulties arise, one being the hardness of the product, which involves expense in grinding the fused production. The work of Kress and Metzgerj indicates that thorium does not occur as the silicate in monazite. It is a fact, however, t h a t silica or silicate is a constant but variable constituent of the sand and must be taken care of whatever means of extraction is applied. When the carbides are made b y electric fusion of the sand with carbon, some silicon carbide is produced which cuts the grinding machinery in the later process of pulverizing. We have found t h a t the addition of a small amount of fluorspar reduces this difficulty, yet the expense of some grinding remains. I n order t o reduce this expense to a minimum, I decided t o deliberately produce calcium carbide within the mass, which, when thrown into water, would disintegrate.6 Although Moissan has shown t h a t thorium and the rare earth( ?) carbides are attacked by water, the speed of the reaction is very much less than with calcium carbide and is also much dependent upon the fineness of the particles. Hence comparatively little of the thorium and rare earth(?) carbides would be decomposed b y such treatment. Many experiments were carried out, with theoretical and practical mixtures, in various types of furnaces (Stockem, Moissan, HCroult, and resistance), with direct and alternating 1 Paper presented at the Eighth International Congress of Applied Chemistry, New York, September, 1912. Comfit. rend.. 116, 1227 (1893). 3 Ann. chim. fihys., [71, 9, 302 (1896); [71 12, 427 (1897); Compt. rend., 122, 573, 1462 (1896). 4 Ann., 820, 260 (1901), German Patent 129,416, Aug., 1901. 5 J . Am. Chem. S o c . , 81, 640 (1909). Application for letters patent on this method of disintegration of fused masses has been made.
*
82 I
Lb. 1 .O
1.10 0.80 0.15
The best results were obtained with such charges b y using a current of 35 volts and 1 2 5 amperes for one and one-half hours. The procedure is a s follows: The mixture (unground sand being used) is made according t o the principles outlined above and then subjected t o electric heat until phosphorus ceases t o come off.2 The mass is allowed to cool and then t o decompose slowly by exposure t o the air or quickly b y placing in water. I n the latter case the acetylene may be utilized, the mass falling t o a fine powder. The dissolved and suspended calcium hydroxide are removed by washing. The residue is treated with hydrochloric acid and the thorium separated from the solution by sodium thiosulphate or other methods. This process is controlled by the Welsbach Light Co., of Gloucester City, N. J., and is published with their consent and approval. COLLEGEOF
THE
CITY
OF
YEW YORK.
THE PRODUCTION OF AVAILABLE POTASH FROM THE NATURAL SILICATES.3 By ALLERTON S. CUSHMANAND GEORGE W. COGGESHALL.
The great demand which has recently arisen for a n American supply of potash in available form for agriculture, has stimulated not only the search for new sources of this material but also experiments on a large and practical scale of operation, in the attempt to develop a method of making the vast supply of potash locked up in feldspars and feldspathic rocks either directly water-soluble or sufficiently soluble in dilute acids t o insure a product which shall be useful as a fertilizer. The natural silicates commercially available a s sources of potash are chiefly orthoclase and leucite. Both of these minerals are potassiumaluminum silicates. The theoretical formula for orthoclase is written K,0.A1,03.6Si0,, and for leucite K20.A1,0,.4Si0,. The principal sodium feldspar, albite, has the theoretical formula Na,0.A1,0,.6Si02. It is well known t h a t these feldspars run into and substitute each other in various proportions so t h a t the products from different quarries will vary widely in respect t o their soda and potash contents. There is a n enormous supply of feldspar in the United States, both east and west, which could be made economically possible as a source of potash supply, provided the cost of production can be maae low enough t o compete with the potash-holding manure salts which are a t present so largely imported from Germany. Although i t must be admitted t h a t the imThe experimental work was done by Mr. S. G. Warner of my staff. This phosphorus may be condensed. a Paper presented at the Eighth International Congress of Applied Chemistry, New York, September, 1912. 1
2
