The Research On Reduction Process Of Copper Slag By Hydrogen

With the development of copper smelting technology,the yield of copper is increased year by year,while the discharge of copper slag is increased.As a useful secondary resource,the contents of both copper and iron in slag are higher than that in ore.At present,the research of utilizing copper slag is mainly aimed on the extraction of copper or iron individually,which cannot effectively utilize both of copper and iron.Few studies were on the simultaneous extraction of both copper and iron,and the studies are mostly using carbon as reductant.In this study,our group proposes a new method for reducing copper slag by hydrogen to obtain molten iron alloy,which is suitable for producing cupreous anti-bacterial stainless steel.In this paper,thermodynamic and kinetic analysis on the process of copper slag reduction by hydrogen were made.The effects of reaction temperature,partial pressure of hydrogen and CaO addition on the reduction process were investigated by single factor experiments and orthogonal experiments.The thermo gravimetric method was used to determine the hermo-gravimetric curve in process of hydrogen-reduced copper slag,then the curve was transformed into the relationship between reduction rate and time.In the kinetic study,apparent rate constants,diffusion coefficient and apparent activation energy were determined by the model of unreacted core.The main contents and conclusions are as follows:(1)The result of thermodynamic calculation shows that both iron oxide and copper oxide in copper slag can react with hydrogen from 950? to 1100?.Other oxides such as Al2O3 and SiO2 cannot react with Hydrogen.The predominance zone diagram of Cu-Fe-O-H and Cu-Fe-S-H show that iron and copper have a co-stable region.The reduction route is.CuO?Cu2O?Cu,Fe2O3?Fe3O4?FeO?Fe?(2)By single factor experiments of hydrogen reduction of copper slag,the optimal reaction conditions are as follow:the reduction temperature is 1100?,the partial pressure of H2 is 40%,the addition of CaO is 30%,the reaction time is 80 min,the reduction rate of copper and iron is 85.04%.Orthogonal experiment of hydrogen-reduction of copper slag show that the main factor on reduction is reaction temperature,then is H2 partial pressure,the last is CaO addition.(3)Melting analysis on the reductive copper slag was made under 1500? and 4 hours respectively.The content of MFe in and Cu in the melted metal 85.11%,and 10.4%.The content of MFe in and Cu in upper slag are 0.30%,and 0.13%.The content of MFe in and Cu in lower slag are 0.69%,and 0.14%.(4)The kinetic process of the hydrogen-reduction to copper slag was discussed.The reaction is controlled by the internal diffusion and interfacial chemical reaction according to unreacted nuclear model.The condition of reaction are:temperature is 950? to 1100?,the apparent rate constants is3.13×10-3 to 7.28×10-3m/s,the diffusion coefficient is 2.87×10-6 to 7.83×10-6m2/s,and the apparent activation energy is 29.107 to 36.082kJ/mol.