Patent GB-966548-A (GB)
Title: Process for the concentration of chromium ores
IPC: C22B34/32
Filed: 1961-01-12
Abstract: In a process for the concentration of chromium in iron-containing chromium ores, the ores are subjected to a reduction treatment in a solid phase at a temperature above 950 DEG  C. with a reducing agent containing at least 7% chromium in the form of a chromium-containing alloy and to one or more subsequent processes of grinding and separation, so as to produce an ore product having an increased chromium to iron ratio and an increased chromium oxide content and a metallic product consisting substantially of iron. The chromium-containing alloy reducing agent may be used in conjunction with another reducing agent, e.g. carbon, calcium, carbide or silicon in the solid state, and the reducing agents should preferably be added in such quantities that substantially only iron compounds are reduced A suitable reducing agent is a high-carbon ferro-chromium, i.e. containing 4 to 8% carbon.  The reduction may be carried out in a sagger, a rotating furnace, a pushing-type furnace or a shaft furnace. The ore to be concentrated is ground and mixed with the ground reducing agent and sodium chloride. After heating, the mixture is ground and magnetically separated, two fractions being obtained-an ore and a metal fraction, the chromium content of the ore fraction being greater than that in the original ore.  An iron-containing chromium ore to be concerntrated may first be mechanically concentrated, e.g. using a shaking table operation, into a heavy and a light fraction. The heavy fraction may be concentrated according to the invention and the light fraction may be used as raw material for the production of the high carbon ferro-chromium reducing agent.ALSO:In a process for the concentration of chromium in iron-containing chromium ores, the ores are subjected to a reduction treatment in a solid phase at a temperature above 950  DEG C. with a reducing agent containing at least 7% chromium in the form of a chromium-containing alloy and to one or more subsequent processes of grinding and separation, so as to produce an ore product having an increased chromium to iron ratio and a metallic product consisting substantially of iron.  The chromium-containing alloy reducing agent, which is preferably a high-carbon ferro-chromium i.e. containing 4-8% carbon, may be used in conjunction with another reducing agent, e.g. carbon, calcium carbide or silicon in the solid state. The reduction may be carried out in a sagger, a rotating furnace, a pushing type furnace or a shaft furnace.  The ore to be concentrated is ground and mixed with the ground reducing agent and sodium chloride. After heating, the mixture is ground and magnetically separated, two fractions being obtained-an ore and a metal fraction, the chromium content of the ore fraction being greater than that in the original ore.  An iron-containing chromium ore to be concentrated may first be mechanically concentrated, e.g. using a shaking table operation, into a heavy and a light fraction.  The heavy fraction may be concentrated according to the invention and the light fraction may be used as raw material for the production of the high carbon ferro-chromium reducing agent.