| High-pressure leaching technology of Zinc Sulfide Concentrate has been developed considerably abroad for having benefits such as short process, environmental protection, low cost and high leaching rate of Zinc, etc. Because we paid more attention to environmental protection and the improvement of resource utilization, the technology has been more and more concerned. However, the technology is still at an initial stage in China, for lacking of deep and systematic theoretical research on rich-oxygen leaching process of Zinc concentrate in China, for lacking of effective methods of post-processing of leaching residue and leaching solution, and for lacking of understanding of balance, transformation and recycling between the elemental sulfur and acid in leaching process. Therefore, it is significant to study deeply and systematically on rich-oxygen leaching process and post-processing of leaching in order to provide scientific basis for the high-pressure leaching process of Zinc concentrate and its practical application in this paper. The valuable research of high-pressure leaching technology was as follows.Firstly, systematically deep discussion on thermodynamics of Zn-S-H20system and metals-S-H2O systems relative to zinc sulfide concentrate were researched, their potential expressions were derived, and the e-pH figures of different temperatures, oxygen partial pressures and activities were drew for determining the existing stable area of Zn2+and S in rich-oxygen leaching of ZnS concentrate. Meanwhile, e-pH figures of Fe-S-H2O and ln-S-H2O systems were drew in the optimum conditions of leaching.Secondly, the factors of particle size, temperature, sulfuric acid concentration, leaching time, oxygen partial pressure, solid-liquid ratio, agitation rate and additive amount on rich-oxygen leaching process of ZnS, synthesized sphalerite and Zinc Sulfide Concentrate were comparatively studied, based on the ε-pH figures of ZnS-H2O system. The results indicated that the temperature, leaching time, agitation rate have significant effects on the leaching rate. The reasonable conditions of oxygen pressure, acid concentration and solid-liquid ratio obtained by experiments were in excellent agreement with the conditions determined by ε-pH figures of Zn-S-H2O system.Thirdly, the systematically research on kinetics of rich-oxygen leaching of zinc sulfide concentrate were made. The results showed that the effect of mineral granularity on metal leaching was great impact, the leaching rate was increasing with the decrease of mineral granularity and inversely proportional to the initial radius r0; the leaching process was controlled by the surface chemical reaction and followed the kinetic law of "shrinking model of unreacted core", and kinetic equation was lnkT=8.85*103/T+5.634, its reaction activation energy was73.58kJ/mol.Forth, the xylene, tetrachloroethylene and ammonium sulfide were used as extractant to extract the elemental sulfur in the leaching residue. The advantages and disadvantages of their technologies were been compared, and the optimum conditions which been used ammonium sulfide to extracting elemental sulfur was screened out. The processes of extracting In, Co, Ag in leaching residue and leaching solution were researched, and the suitable conditions to extract them were obtained.Lastly, transformation and equilibrium relationship between SO42-and S in the leaching process were calculated, the concept of acid balance in rich-oxygen leaching process was proposed, and the transformation and cyclic condition of S of zinc sulfide concentrate in rich-oxygen leaching was derived in theoretically. The acid balance of the transformation and circle of S in rich-oxygen leaching process were certificated by experiments. It has very important significance for rich-oxygen leaching of zinc sulfide concentrate production in acid scarcity area. At present, the new technology has been used to guide the production of rich-oxygen leaching in Yunnan Metallurgy Group. |
PDF Full Text Request