GB394846A - Improvements in or relating to processes of treating oxidized ores - Google Patents

Abstract

Oxidized ores containing "reagent metal" are heated to 300-750 DEG C. in a reducing atmosphere containing a combustible reducing agent and sulphur dioxide, then cooled with exclusion of free oyxgen and preferably also of moisture to obtain "reagent metal" compound in an active condition and finally treated with an acidic reagent gas or gases, such as chlorine, hydrochloric acid, ferric chloride, or sulphur dioxide. Alternatively, active "reagent metal" compound may be separately prepared and added to the ore. "Reagent metals" are those capable of exhibiting more than one valency and include nickel, cobalt, copper, and manganese, though iron is the preferred reagent since a highly active magnetic oxide results from the reducing treatment described above which enables the desired metal values to be separated magnetically from the gangue. The reducing agent may be producer gas, natural gas, hydrogen, or coal, and when a sulphurbearing coal is used it may supply the sulphur dioxide necessary. Less than 1 per cent of sulphur dioxide in the reducing atmosphere suffices, but amounts up to 75 per cent may be p used. In one example, a Cuban iron ore containing chromium and nickel is reduced with natural gas or finely divided coal in the presence of sulphur dioxide at 600 DEG C., rendered "quasi-wet" after cooling, treated with chlorine and roasted at a low temperature to chloridize the nickel; or the cooled reduced ore may be treated dry with chlorine at 300 DEG C. After leaching to remove nickel, the residue may be treated to obtain a chromium concentrate and leave a tailing rich in iron oxide. In another example a roasted copper ore containing iron is reduced with coal in the presence of sulphur dioxide, made "quasi-wet" after cooling, and treated with chlorine. Leaching the chlorinated product removes substantially all the copper. In a third example, a roasted sulphide ore containing copper and nickel and some residual sulphide is reduced with coal at 600 DEG C., made "quasi-wet" after cooling, and treated with chlorine. The amount of water-soluble copper and nickel is increased by providing additional sulphur dioxide during the reducing step. The treatment of an oxidized iron ore containing phosphorus and manganese is also referred to. In each case details are given of the results when reduction is effected without adding sulphur dioxide.