Abstract: A process is provided for extracting tungsten values from tungsten compositions. The process comprises treating a tri (alkaline earth metal) tungstate, especially tricalcium tungstate, at a temperature of preferably no greater than 50.degree. C. with a aqueous solution of hydrochloric and/or nitric acid, preferably having a concentration of no greater than 5 molar. The acid is supplied in excess of te stoichiometric amount required to convert the tungstate to tungstic acid and sufficient to maintain the thusly formed tungstic acid insoluble in the solution. The tungstic acid can then be separated from the solution and converted to soluble ammonium tungstate, which in turn can be converted into tungsten trioxide and finally into metallic tungsten. The tri (alkaline earth metal) tungstate starting material can be prepared from iron tungstate, manganese tungstate, and/or an alkaline earth metal tungstate or from ores or concentrates of these tungstates, by a high temperature treatment with calcium oxide.

Abstract: A process for the treatment of lead sulphide with an aqueous solution of sulphur dioxide at a temperature of at least 20.degree. C and in the absence of oxygen is disclosed. In a preferred embodiment the lead sulphate and/or lead sulphite so formed is heated with lead sulphide at a temperature of 700.degree. to 1200.degree. C in the absence of oxygen. Metallic lead is obtained. In the preferred embodiment the lead sulphide may contain zinc sulphide whereby both metallic lead and metallic zinc may be obtained.