METHOD FOR PROCESSING COPPER SMELTING MATERIALS AND THE LIKE CONTAINING HIGH PERCENTAGES OF ARSENIC AND/OR ANTIMONY

摘要

ABSTRACTThe invention relates to a method for preparing a sulphidic concentrate whichis intended for further processing to copper and/or precious metals and whichcontains high percentages of arsenic and/or antimony, and possibly also bismuthin quantities likely to disturb subsequent processing stages, by partially roastingthe concentrate in a fluidized bed, so as to eliminate substantially all the arsenicpresent and a major part of the antimony and/or bismuth. According to theinvention, the concentrate and gas are supplied to a fluidized-bed reactor,and are there heated to a minimum temperature above the splitting or decompo-sition temperatures of the complex minerals containing arsenic and/or antimonyand bismuth present in the concentrate. The oxygen potential in the reactoris regulated, so as to prevent the formation of non-volatile compounds of saidimpurities. The residence time of the concentrate in the reactor is controlledin a manner to ensure a given minimum elimination of the impurities. Thegas and solids are withdrawn from the reactor and passed to a separating means,in which substantially impurity-free solids can be separated from the gas. Theaforesaid minimum temperature and said regulated oxygen potential are main-tained while the solids are in contact with said gas, and at least a part of theseparated solids is returned to the reactor, for controlling the residence time,and an end product is removed from the fluidized bed and/or the separatingmeans. The method is suitably carried out in one stage in a fluidized-bed reactorhaving a circulatory fluidized bed, although in certain cases the method canbe carried out in two stages, in mutually separate reactors.