Theoretical Analysis And Experimental Study On One-step Copper Smelting Of Chalcocite

Chalcocite has high copper content,low sulfur content and low iron content.If traditional pyrometallurgical smelting is used,there are two main problems:the sulfur content in the concentrate is low,and it is difficult to realize self-heating smelting,and external heating is required;the slag type is difficult to control stably,and it cannot reach the level of copper in the slag in conventional smelting slag.Therefore,it is necessary to conduct direct-to-blister research on this type of ore.Direct-to-blister technology has the characteristics of strengthening the smelting process,increasing productivity,reducing fuel consumption and production costs,and simplifying the smelting process.This process will become the focus of research in the pyrometallurgical copper industry in the future.In this paper,chalcocite is used as the raw material,and the Fact Sage thermodynamic software is used to conduct thermodynamic analysis of the direct-to-blister process.Due to the precipitation of SiO₂ in direct smelting of chalcocite,the viscosity of the slag increased and the fluidity was poor,so normal smelting cannot be carried out.According to the analysis of the phase diagram,three types of adjustment schemes for the one-step copper smelting slag type of chalcocite are obtained:maintain the iron-silicon ratio of the original slag system,and directly add CaO to make the slag composition point in the slag liquid phase region;Add pyrite to adjust the slag iron-silicon ratio so that the slag composition point is in the slag liquid phase area;Adjust the slag system iron-silicon ratio and the amount of CaO at the same time so that the slag composition point is located in the slag liquid phase area.The three schemes are analyzed in detail and optimized and adjusted,and the optimal control scheme for the thermodynamics of direct-to-blister of chalcocite is obtained.The specific smelting parameters are:the slag viscosity is 0.49?0.69Pa·s,and the blister copper grade is 99.12?99.36%The direct yield of copper is between 88.06%-95.37%,and the S content of blister copper is stable at about 0.5%.Under theoretical conditions,1t blister copper is produced,and about 0.79?0.94t copper slag is produced.In theory,direct-to-blister of chalcocite can be realized.The feasibility control plan of the slag type was verified by experiments,and the experimental data was analyzed by chemical composition analysis,XRD,EPMA and other methods.Because the theoretical calculation cannot calculate the mechanical entrainment loss of copper in the slag,the copper content in the slag obtained from the experiment is higher than the theoretical value,which leads to a lower copper yield than the theoretical value.The grade of blister copper is close to the theoretical value,and the sulfur content of blister copper fits the theoretically calculated value.In the experimental results obtained,the direct yield of copper is between 80%?91%,and the copper content in the slag is in the range of 8%?15%.The experimental results are in good agreement with the theoretical calculations,indicating that direct-to-blister of chalcocite can be achieved under laboratory conditions.