| For a long time, it produce many kinds of metallurgical slag in metallurgical production process, is often ignored by people. Now, the metallurgical enterprises are faced with the double pressure of environment and resources, environmental protection treatment and resource utilization of metallurgical slag has become the consensus of people. In the process of zinc hydrometallurgy in a company, produce a certain amount of copper slag, copper slag mainly containing copper20%-40%, lead15%-30%, zinc2%-8%, cadmium1%-5%, also contains a small amount of silver (400-600g/t), germanium (500～800g/t), etc. Copper slag used to sales in the form of industrial slag and only copper, silver and germanium are valued. Other valuable metals, such as lead, zinc, cadmium are not valued. To comprehensively utilize copper slag will produce certain economic benefits and social benefits. After preliminary work, comprehensive recovery of copper slag use the technology of "copper slag-direct leaching-concentration and crystal-deposition of copper-copper sulfate pentahydrate", and carried out experimental study of technical conditions including pressure, normal pressure, concentration and crystal, deposition of copper. The purpose is to use low pressure or normal pressure to reduce the safety risk, to ensure the high leaching rate, comprehensive recover the copper, lead, silver and other valuable metals such as germanium, zinc and cadmium, all of the waste residue and waste water are comprehensive utilized, the quality of products come up to the requirement of the industrial level1of YS/T94-2007standards, and to provide technical support for build a set of production line of copper sulphate pentahydrate which production capacity are800tones. This paper discussed the influence of time, temperature, oxygen concentration, solid-liquid ratio, stirring speed and sulfuric acid concentration on leaching of copper slag. Obtained the optimum leaching conditions: temperature80℃, the liquid-solid ratio4.5, sulfuric acid concentration105g/L, oxygen concentration30%or higher, oxygen pressure0.2MPa, time4h～6h and the stirring speed500r/min. In these technology conditions, the valuable metal leaching rate of copper slag are copper≥92%, cadmium≥99%, zinc≥46%, germanium≥70%, indium≥70%. By evaporation and crystallization experiments, it is concluded that the suitable operating conditions and operating system is:concentrate and evaporation to the density of1.38,then hot filtration. The hot filtrate continued to evaporate to density of1.44, then cooling by slowly stir to room temperature for2h, filtrate. The filtrate continued to evaporation to the density of1.50, then cooled to room temperature and crystallization2h by stir slowly, filtrate. The coarse crystals through four hot water countercurrent washing, washing temperature80℃, liquid-solid ratio of1.2:1.After washing crystal are dried and packed.1m3copper slag leaching solution (concentration of Cu2+is51.93g/L) output coarse crystal and secondary coarse crystal count up to216.5kg. In evaporation concentration and washing process, total copper recovery rate was94.45%. Second mother liquid through deposit germanium by tannins and neutralization by lime milk to remove arsenic and iron, then use zinc powder to deposit copper, copper deposition rate can reach98.87%, the grade of sponge copper up to90.68%, the effect deposition is good. Deal with one tonne copper slag (dry) producing copper sulfate pentahydrate, the product leaching slag, germanium slag and sponge copper total value is Y20119.6, gross profit margin is￥3970.15/tons copper slag. It has good processing profits. The completion of the project not only has important significance for energy conservation and emissions reduction, but also great significance for speed up the realization of environmental protection treatment and resource utilization of metallurgical slag. |
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