Experimental Study On The Microwave-assisted Leaching Of Cu And Zn From Copper Smelting Dust

The consumption of copper is much more than copper productivity in China, and the demand of consuming copper increases more rapidly than the increased capacity of refined copper per year, thus more efforts and focus should be put on the research and development of recycling technology for secondary resources in order to change the present situation of copper shortages. Copper-smelting dust, one of the copper-contained secondary resources, has high recovery value for the valuable metals such as Cu and Zn. Microwave heating, as one environmentally friendly metallurgical method that develops rapidly in recent years, draws wide attention and research for its features as self-heating, energy-reservation, easy way to control, safe and eco-friendly.We studied the leaching process of Cu and Zn from copper-smelting dust on the microwave-assisted.Copper ferrite and zinc ferrite are the primary formations of Cu a nd Zn in copper smelting dust. Leaching experiment for material was performed with sulphuric acid after roasting with carbon. The effects of leaching rate of Cu and Zn by different factors was studied by single factor experiments. Though orthogonal experiments. The best experimental conditions of copper leaching, obtained from the results and analysis of a series of experiments, were found to be at 80?, with sulfuric acid concentration as 5mol/L, leaching time as 2 hours, the size of copper smelting dust is over 74?m, and liquid-solid ratio as 20:1, and the best experimental conditions of zinc leaching at 80?, with sulfuric acid concentration as 2mol/L, leaching time as2 hours, the size of copper smelting dust is over 74?m, and liquid-solid ratio as 20:1.The minor effect of size indicated that microwave heating could accelerate the leaching of Cu and Zn from copper-smelting dust of bigger size,and the primary influencing factor was found to be liquid-solid ratio.Further dynamic investigation of the leaching of Cu and Zn with microwave heating indicated that, at the temperature between 298 K to 353 K, the leaching was shrinking unreacted core model.The apparent activation energy of Cu is 10.34kJ/mol and the the apparent activation energy of Zn is 18.19kJ/mol, leaching process was mainly controlled by the diffusion in boundary layer of solid product.The series of experiments and dynamic analysis in this paper provides a theoretic and practical reference for the leaching of Cu and Zn from copper-smelting dust with microwave heating. It also gives a proof of the acceleration of microwave heating in leaching process and makes a guidance for industrialized application ofcopper-smelting dust treatment.