GB332627A - - Google Patents

Abstract

332,627. Siemens & Halske Akt.- Ges. Nov. 22, 1928, [Convention date]. Extracting rhenium. - In the extraction of rhenium from minerals such as columbite, gadolinite, or magnetic pyrites, the mineral is brought into solution for instance with hydrochloric or sulphuric acid and the rhenium then precipitated as sulphide, as with hydrogen sulphide, together with other sulphides so precipitated. The precipitate from a solution in hydrochloric acid of magnetic pyrites containing 0.0001 per cent rhenium may contain arsenic, molybdenum, and rhenium only. Further treatment may comprise repeated solution of the sulphide precipitate in nitric acid, precipitation of constituents other than rhenium with ammonium nitrate and phosphoric acid or a phosphate, and reprecipitation of sulphides by hydrogen sulphide. Finally when the rhenium is sufficiently concentrated it may be recovered as by fractional sublimation, the, sulphide concentrate being reduced by hydrogen and then gently heated in a current of oxygen, reduction, fractional volatilization, and reoxidation of the sublimates being repeated to separate the rhenium. It is stated that rhenium may be similarly removed by fractional sublimation of a mixture of chlorides. Mineral such as columbite containing as a main constituent an acid of an amphoteric metal may be first treated to render such acid) insoluble, as by fluxing with potassium bisulphate and extracting with water, with separation in the case of columbite of niobic acid. Specification 317,035 is referred to.