Abstract: A process for recovering tungsten as an ammoniacal tungstate which comprises reacting a tungsten containing material with sodium hydroxide to produce sodium tungstate and forming a first aqueous sodium tungstate solution therefrom, crystallizing sodium tungstate from the first aqueous sodium tungstate solution, dissolving the resulting sodium tungstate crystals in an aqueous medium to form a second aqueous sodium tungstate solution, extracting tungsten from the second aqueous sodium tungstate solution with an organic extracting agent wherein the extracting agent containing tungsten is capable of being stripped of the extracted tungsten by ammonia, and thereafter stripping the extracted tungsten from the organic extracting agent with ammonia to form an ammoniacal tungstate solution, crystallizing a portion of the tungsten contained in the ammoniacal tungstate solution to form a two phase system wherein an ammoniacal tungstate compound comprises the first phase and wherein the resulting mother liquor containing

Abstract: In the manufacture of ammonium paratungstate, sulfide is added to a tungsten-containing solution in order to precipitate molybdenum sulfide. Volatiles, including sulfides, evolved during this process are collected in a caustic scrubbing solution. The sulfide values in the caustic scrubbing solution may be reused to precipitate molybdenum sulfide by first treating the caustic scrubbing solution with alkaline earth chloride or sulfate to precipitate out alkaline earth carbonate.

Abstract: A process is disclosed for removing ammonia from a sodium tungstate solution. The process involves heating the solution at from about 80.degree. C. to about 95.degree. C., while at the same time maintaining the pH above about 9.4 by addition of sodium hydroxide to the sodium tungstate solution. The heating is carried out for a period of time sufficient to allow the essentially complete removal of the ammonia.

Abstract: A method is disclosed for removing tin from aqueous sodium tungstate solutions. The method involves adding ammonia to the sodium tungstate solution, adjusting the pH to above about 9.5 with an acid, adding magnesium chloride to form insoluble material containing the major portion of the tin, silicon, arsenic and phosphorus and a resulting sodium tungstate solution containing the major portion of the tungsten, and separating the insoluble material from the resulting solution.

Abstract: In a process for producing pure ammonium paratungstate from ammonium tungstate solutions containing tin, sulfide is added to the ammonium tungstate solution in an amount sufficient to form a soluble complex of the sulfide with the tin. The solution is then evaporated to a volume at which essentially all of the tungsten is in the form of insoluble ammonium paratungstate and essentially all of the tin is in the mother liquor in the form of a soluble complex along with other impurities. The solid ammonium paratungstate is then separated from the mother liquor by filtration.

Abstract: In a continuous process for producing ammonium tungstate from aqueous alkali metal tungstate solution according to an extraction process, the loaded organic extractant is cleaned after stripping by contacting with activated carbon for improving phase separation and decreasing the concentration of alkali metal.

Abstract: In a two component extraction system for producing ammonium tungstate from aqueous alkali metal tungstate solution, the stripping solution consists essentially of water and from about 5 to about 21 percent by weight ammonium hydroxide at a pH of from about 12 to 13 wherein the stripping is carried out by dispersing the aqueous ammonia solution in the loaded organic extractant.

Abstract: In a three component extraction system for producing ammonium tungstate from aqueous alkali metal tungstate from aqueous alkali metal tungstate solution, the stripping solution consists essentially of water and from about 5 to about 21 percent ammonium hydroxide at a pH of from about 12 to about 13 wherein the stripping is carried out by dispersing the aqueous ammonia solution in the loaded organic extractant.

Abstract: In a two component extraction system for producing ammonium tungstate from aqueous alkali metal tungstate from aqueous alkali metal tungstate solution, the stripped organic is washed to form a wash solution which is mixed with concentrated ammonia solution to form an aqueous ammonia solution which is mixed with product ammonia tungstate and fed as the stripping solution for contacting the loaded organic extractant.

Abstract: Tungsten is recovered from tungsten ore concentrates in the form of sodium tungstate by a basic process in which ground ore is first digested in a sodium hydroxide solution followed by diluting the solution to dissolved sodium tungstate separating the solution from the caustic insoluble sludge and crystallizing soluble sodium tungstate, wherein the present invention permits improved recovery of tungsten from difficult to process ores by the process steps of comminuting said tungsten ore concentrate to a particle size less than about 200 mesh, adding the comminuted ore to an aqueous solution of sodium hydroxide at a temperature from about 10 to about 30 degrees centigrade, dispersing said comminuted ore in the aqueous solution of sodium hydroxide prior to digestion, digesting at a temperature of from about 75.degree. C. to about 150.degree. C.