Abstract
Effects of the various factors such as pH, temperature, dissolved oxygen, potential (or oxidation) and the reciprocal reaction with the solid particles of another metal sulfide, on the leaching of sulfide have been investigated for the purpose of clarifying the dissolution behavior of sulfides in dilute acid solution. Generally, many sulfides possess properties of a compound semiconductor. The conspicuous changes in the electric special character of semiconductor under illumination are known. Therefore, it is considered that the influence of illumination in the case of leaching should not be disregarded. However, there are few reports about this. In this investigation, the experiments on the effects of illumination were carried out in order to elucidate the dissolution mechanism of ZnS in acid solution and the galvanic reciprocal reaction of the direct selective leaching of ZnS from ZnS-CuS mixture concentrates.
The experimental results obtained are as follows:
(1) In the case of ZnS alone, the ZnS dissolution of H2S-evolution type was accelerated by illumination and its amount of dissolution increased.
(2) The galvanic reciprocal reaction of ZnS-CuS mixture concentrates was accelerated by illumination in the dilute acid solution at pH 1. ZnS was leached in accord with the dissolution reaction, ZnS=Zn2++S0+2e. This reaction was promoted with larger light energy.
(3) The ZnS dissolution of the H2S-evolution type from ZnS-CuS mixture concentrates was accelerated by illumination in the acid solution at lower pH such as −0.5.
