| Hard zinc is a product in distillation refining of coase zinc,which was produced by the ISP process, also it is one of the important raw materials of extracting germanium. A factory produces lead and zinc by ISP process, the lead and zinc concentrate used by the factory bearing germnium0.005%～0.0065%. The content of germanium in hard zinc which was produced in the coase zinc refining is about0.2%. After getting rid of zinc by vacuum distillation,germanium can be enriched more than10times and the content of germanium in vacuum furnace slag can be up to2%.Germanium in vaccum furnace slag was recoveried by the process of neutral leaching-oxidizing roasting-chlorinated distillation.In this papers the vacuum furnace slag after neutral leaching and oxidizing roasting was regard as raw material, and the leaching technology and dynamics of the oxidizing roasting slag in HCl-CaCl2-H2O system by using calcium hypochlorite as oxidant was studied.The thermodynamic of Me(Ge, Pb, In, Ag)-C1--H2O, and As-H2O system was calculated at the begin of the paper, the E-pH diagrams of Ge-Cl--H2O, Pb-Cl--H2O, In-Cl--H2O, Ag-Cl--H2O and As-H2O system under normal temperature was painted. The results show that germanium, lead, indium, silver and arsenic can be oxidated by calcium hypochlorite in oxidation leaching and the existence of Cl-can reduce the REDOX potentials of germanium, lead, indium and silver.Then, the leaching technology of germanium in oxidizing roasting slag in HCl-CaCl2-H2O system was investigated by using orthogonal and single factor experiment methods. The orthogonal experiment results show that the leaching temperature, the oxidant amount used, hydrochloric acid concentration, calcium chloride concentration and leaching time have an effect on the leaching rate of germanium in oxidizing roasting slag, the order of infuence sizes is the leaching time, hydrochloric acid concentration, calcium chloride concentration and leaching temperature. The single factor experiment results show that the leaching rate of germanium can be increased by rising the leaching temperature, decreasing the particle size of the sample, increasing the hydrochloric acid and chloridion concentration and liquid to solid rate. Optimum conditions for leaching of germanium were determined as follows:leaching temperature was95℃, the hydrochloric acid concentration was5mol/L, the chloridion concentration was9mol/L, the dosage of oxidant was2times of theoretic value, and leaching time was80min, and the leaching rate of germanium can be up to83.06%in the optium extraction conditions.In the end the leaching dynamics of germanium in oxidizing roasting slag was studied. The results show that the leaching rate of germanium in oxidizing roasting slag was increased and the balance time of leaching was shortened by rising the leaching temperature, decreasing the particle size of the sample, increasing the hydrochloric acid and calcium chloride concentration, and liquid to solid rate.The leaching process could be described with the without reaction shrinking core model, and diffusion through the product layer was the controlling step.The activation energy was calculated to be21068J/mol. A leaching macro dynamic equation as following was also fitted to describe the leaching process:1-2x/3-(1-x)2/3=1.47×10-5×CH+1.027×CCl-3.039×D-0.862×(S/L)-0.75×exp(-21068/RT)t。... |
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