| 摘要 |
Sulphidised nickel silicate and/or sulphidic nickel ores and/or concentrates in the form of dry and/or wet pellets or filter cake, wetted down material or slurries mixed with fluxes, to avoid dust, are added to, or as powder, pneumatically injected into, a turbulent bath consisting mainly of matte and slag, which is agitated by a stream of combustion gas, derived from natural gas, fuel oil or powdered coal, with a measured excess of oxygen. Nickel ores and concentrates are associated with iron to a greater or lesser extent, and may also be associated with one or more of cobalt, copper and the noble metals. Oxidation of the molten bath, which takes place at about 1250<o>C is selective and controllable, and the iron sulphide in the matte is oxidised to iron oxide and forms a silicate slag, with silicates already present in the ores and/or concentrates, or silica added as a flux. This leaves an enriched nickel (cobalt, noble metal) matte, in which the nickel content may range from 45 to 75%, from which nickel may be readily and economically recovered as a useful nickel matte product, (2% max. S), by partial conversion with available free and/or combined oxygen, under conditions of a mildly oxidising gas flush or substantially reduced pressure, at 1450<o>C and upwards. Any nickel reporting in the slag may be recovered by carbonaceous or gaseous reduction, and recycled to the charge. The process may be carried out in a known crucible-type furnace, as exemplified in the drawing. |
