Abstract
The interaction of sulfide particles of the zinc sulfide-lead sulfide system suspended in dilute sulfulic acid solutions was studied in order to obtain foundamental data on acid leaching processes. The experiments were carried out under the following conditions: temperature: 25∼70°C, pH value: 0.5∼2, amounts of sulfide: 5×10−1∼2×10−1 M/L, air pressure: 1∼2 L/min and agitation speed: 600 rpm. The experimental results were summarized as follows:
(1) The main dissolution reaction of ZnS in the solutions was the type of H2S formation and showed a parabolic behavior. The reaction was diffusion control.
(2) The main acid dissolution reaction of PbS in the solutions was the type of H2S formation. The reaction rate followed a linear law and the activation energy was 9.1 kcal·mol−1.
(3) The dissolution of ZnS and PbS in the ZnS-PbS system suspended in the solutions was observed in the following two types:
(i) The dissolution of ZnS proceeds during the measurement and the acid dissolution of coexisting PbS is repressed remarkably.
(ii) In the early stages of the reaction, the dissolution of ZnS proceeds and the acid dissolution of the coexisting PbS is repressed. After the lapse of a certain time, however, the dissolution of ZnS is repressed and the acid dissolution of the coexisting PbS starts.
(4) The repression of dissolution of ZnS in the ZnS-PbS system suspended in the solution can be explained by the effect of the S0 films produced at the ZnS surface.
