Process for sulphating the non-ferrous metals contained in ferruginous sulphide ores or sulphidic roasts

摘要

Non-ferrous metals contained in pyrites, mixed sulphide ores or sulphidic roasts are sulphated by charging the originating materials into a furnace wherein they are passed countercurrent to the gases and are raised to the sulphating temperature under conditions preventing oxidation of the non-ferrous metal sulphides, whereupon a combustible ferruginous contact substance in pulverulent form, e.g. flotation pyrites is blown in and burned. Combustion of the pulverulent pyrites maintains the sulphating temperature, increases the sulphur dioxide concentration, and produces ferric oxide which acts catalytically in the oxidation of sulphur dioxide to sulphur trioxide. The combustible contact substance may be replaced by pulverulent ferric oxide or roasted ore containing it, with simultaneous introduction of hot roasting gases, alone or in conjunction with a fuel, or a substance furnishing sulphur dioxide. A sulphating temperature of 450--600 DEG C. is employed. The furnace is preferably of the mechanical multi-stage or rotary type provided with air openings over its length and perimeter. When raw ore is treated, the sulphur of the pyrites is burned off in the first part of the furnace. When sulphidic roasts, e.g. Meggen pyrites (containing zinc sulphide), are treated, almost the whole of the furnace is devoted to the sulphating operation.