Mar., 1919
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY
linseed oil; >kauri Chinawood oil.
and linseed oil; M-rosin
and
METHODS O F ANALYSIS
For the thinner and ash we used the usual methods. For rosin we used McIlhiney’s method substituting Wolff’s esterification method in the place of Twitchell’s and making a few other minor changes. For t h e separation and estimation of resins and oils we used Boughton’s,l Darner’s,2 and Twitchell’s, and Scott’s methodc;. RESULTS
I n the table below we have used the following abbreviations: B = Boughton’s method; D = Darner’s method; T = Twitchell’s method; S = Scott’s method. CONCLUSIONS
The results of the analyses show t h a t Boughton’s method, although it is long and tedious, is satisfactory for resins and oils. We believe i t gives the actual values t o within one per cent. The estimation of rosin is accurate t o probably three-tenths of one per cent. We have spent a good deal of time endeavoring t o find a shorter method. As the extracting in Boughton’s method is made with ether from an aqueous solution containing alcohol, we tried to find a solvent that would not require alcohol t o break the emulsion. A large number of solvents were tried but none gave good results. This problem will be included in our next year’s work. ACKNOWLEDGMENT
The writer wishes t o express his thanks t o Dr. E. F. Ladd, who not only suggested the work but gave advice and encouragement while it was in progress. CHEMICAL LABORATORY
AGRICULTURAL COLLEGE AGRICULTURALCOLLEGE, N. D.
NORTH DAKOTA
THE REDUCTION OF TUNGSTIC
0 x 1 ~ ~ 3
By C. W. DAVIS Received August 19, 1918
Powdered metallic tungsten is being produced a t the present time by several industrial concerns for use in the manufacture of alloys. The available literature on the seduction of tungstic oxide t o the metal, although extensive, fails t o give definite information concerning the conditions involved. The following work was undertaken t o supplement existing data. G E S ERAL
lIennicke4 shows that tungstic acid, as it comes from the filter press after its precipitation with acid, contains considerable water. When air dried, there is still over 7 per cent total water in the material. This must be removed before reduction, for the steam that would be liberated during the heating would cause the material t o fly in all directions, thus tending t o separate the tungstic oxide from the reducing material (when carbon in some form is used) due t o the great difference in their specific gravities. Even when dried in a 1
Bureau of Standards, Technologic P a p e r 65.
* N. D. Agr. Expt. S t n . , Pain8 Bulletin, 1, No. 6 . 3
4
Published by permission of the Director of the U. S. Bureau of Mines. “Die Metallurgie des Wolframs,” 1911, p. 183.
20I
current of air at 100’ C., 3.7 per cent total water remains. To get a sufficiently dry product, the material must be dried in a current of air a t about 5ooo C. This may be done in either reverberatory or revolving furnaces. For all reduction experiments, the tungstic oxide was thoroughly dried a t j o o o C., the color changing from a pure yellow t o a greenish yellow. For a satisfactory reduction, the dried tungstic oxide must be in a state of fine division, and if reduced with some form of carbon, should be completely mixed with it. The most satisfactory treatment consists of grinding together the tungstic oxide and the carbon in a tube mill. Steel or wooden balls should be used, as Mennickel states, for porcelain or flint introduces more impurities. The purpose t o which the finished product is to be put, however, determines the permissible impurities. When the tungsten powder is t o be added t o molten steel for the manufacture of tungsten steel, traces of iron or manganese are not injurious, and silica goes into the slag. It is well, as Mennicke and others’ suggest, t o use some form of binding material when preparing this mix for reduction. Since the specific gravities of tungstic oxide and carbon are so different, their segregation during the processes of reduction is quite apt t o occur. Colophonium, being itself a good reducing agent, easily obtained in a pure condition, and easily pulverized, is t o be recommended. The quantity of this material used by different operators varies from I O to 3 0 per cent of the carbon requirement of the reduction. PRELIMINARY EXPERIMENTS
The material used in the experiments described in this article was an impalpable, canary-yellow powder. As received, the tungstic acid gave off 8.3 per cent of water a t a temperature of j o o o C. Analysis of the tungstic oxide, dried a t 500’ C., showed a tungstic oxide content of 99.4 per cent; insoluble in potassium hydroxide, 0 . j j per cent (largely silica). The reduction processes used are conveniently treated in two sections, that of using some form of solid carbon being the more common, while the reduction performed by some reducing gas gives a purer product. I n both cases, the reduced material must be cooled in a reducing atmosphere as the powdered tungsten readily oxidizes when heated. The oxidation, once started, is pyrophoric in action, and is incandescent after the removal of the source of heat. The temperature necessary for the reduction of tungstic oxide t o the metal, using some form of carbon, is given variously, ranging all the way from red heat up to the temperature obtained with the electric furnace. The following preliminary tests on small samples show what takes place: Tungstic oxide was mixed with carbon (sugar charcoal). The samples were placed in porcelain crucibles, the covers being luted on with fire clay. The results in Table I indicate t h a t a t a temperature of 6 ; 0 ° t o X
