Abstract:In view of the low leaching rate of high iron sulfide zinc ore treated by the present hydrometallurgical zinc smelting process, a method of pre-oxidizing roasting ore samples by adding a certain amount of CaCO3 is put forward in this paper, so that the ZnS ore phase can be transformed into a easy leaching ZnO. The results show that when the CaCO3 was not added in the iron sulfide zinc ore, the ZnS in the ore could not be completely oxidized to ZnO under the conditions of roasting temperature 700 ℃ and time 1h, and the difficultly leached ZnFe2O4 was produced in the roasted products. When the CaCO3 was added with a molar ratio of Ca:S =1:1, the ZnS in the ore could be completely oxidized to the easily leached ZnO under the same conditions, and Ca2Fe2O5 rather than ZnFe2O4 was observed in the roasted products. At the same time, the added CaCO3 was converted into CaSO4 during the process of oxidation roasting. Therefore, the addition of proper amount of CaCO3 in the iron sulfide zinc ore can not only promote the phase transformation of sphalerite (ZnS) and pyrite (FeS2) during the roasting process, but also inhibit the production of ZnFe2O4 by forming Ca2Fe2O5, and fix the sulfur by forming CaSO4. Meanwhile the above results are in good agreement with those predicted by thermody.

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