GB358494A - Improvements in the manufacture and production of pure metals - Google Patents

Abstract

In the process of purification of impure iron and alloys of iron with metals that form volatile chlorides such as nickel, cobalt, chromium, vanadium and titanium, and silicon by treatment with chlorine, hydrogen chloride or gases containing them at elevated temperatures, for example in a rotary tube furnace, the chlorides are separated from the impurities of the material by volatilization and may be obtained in the case of the alloys, together, or if desired, separately by a fractional volatilization or by volatilizing them together and extracting by means of suitable solvents. Further purification of the chlorides may take place by redistillation, resublimation, extraction by solvents and reprecipitation, and they may be wholly or partially converted into the corresponding oxide or oxychloride by oxidation or hydrolytic dissociation, for example, by treatment with steam.ALSO:Pure iron is obtained by treating impure iron at elevated temperatures with chlorine or hydrogen chloride or gases containing them, separating the iron chloride formed from impurities by volatilization and reducing it by means of hydrogen if desired after further purification. The chloride may be completely or partially converted into the corresponding oxide or oxychloride before reduction to metal, by oxidation or hydrolytic dissociation, for example by treating the chloride with steam. The initial materials may comprise instead of iron, impure alloys of iron and metals (including silicon in this term) capable of forming volatile chlorides. The metal chlorides may be obtained separately by a fractional volatilization or by volatilizing them together and extracting by means of solvents, and reduced to obtain the pure metals. By not separating the chlorides or by separating them and subsequently bringing them together again after reduction if desired, of one or more of them substantially pure alloys can be obtained. The examples describe the purification of cast iron, ferrochromium containing about 63 per cent of chromium, 29 per cent of iron, and 6-8 per cent of carbon, an alloy containing 73 per cent of iron, 7 per cent of nickel, and 20 per cent of chromium, and ferrosilicon containing 70 per cent of silicon. The chloridizing may take place in a rotary tube or shaft furnace and the reduction in a tube furnace.