Study On Slag Properties In Synergistic Smelting Of Cyanide Slag In Gold Smelting

With the continuous development of China’s gold industry,a large number of cyanide tailings are produced every year.The cyanide tailings contain highly toxic cyanides,and also contain valuable metals such as gold,silver,copper and lead that can be comprehensively recycled.If not treated,it not only occupies a large amount of arable land,seriously pollutes the environment,but also wastes valuable metal resources.At present,most of the cyanide tailings are stacked in the open air,only a small part of the detoxification and valuable metal recovery.The main reason is that it is difficult to solve the bottleneck problems of complete cyanide removal and low recovery rate of valuable metals.At present,the environmental protection requirements of industrial enterprises in China and abroad are increasingly stringent,so it is of great significance to develop an economic and effective cyanide tailings treatment process.Collaborative smelting is a new process method for efficient treatment of cyanide tailings.Industrial tests show that the harmless resource utilization of cyanide tailings can be realized.The addition of cyanide tailings into copper smelting is bound to bring a lot of influence to the smelting process.In particular,the components such as Fe2O3 and MgO with high content in cyanide tailings have a great influence on the properties of slag in the smelting process,which will seriously affect the normal production of copper smelting.In this paper,the effects of Fe2O3,MgO and other components with high content in cyanide tailings on the properties of slag were systematically studied,providing a theoretical basis for slag type selection in the process of cyanide slag blending with copper smelting.The main research results are as follows:(1)The effects of Fe/SiO2 on melting temperature,viscosity,slag structure and viscous flow activation energy of Fe2O3-FeO-SiO2-3wt%Al2O3-3wt%MgO-8wt%CaO six-element slag system were studied.The melting temperature of slag can be divided into two situations with the change of Fe/SiO2:at low Fe2O3 content(4 wt%,8 wt%),the melting temperature of slag gradually increases with the increase of Fe/SiO2.The melting temperature of slag decreased first and then increased with the increase of Fe/SiO2,at high Fe2O3 content(12 wt%,16 wt%).The slag viscosity η and viscous flow activation energy Eη gradually decrease with the increase of Fe/SiO2.The analysis of the slag structure by FT-IR and Raman showed that the increase of Fe/SiO2 contributed to the depolymerization of slag.(2)The effects of Fe2O3 on melting temperature,viscosity,slag structure and viscous flow activation energy of Fe2O3-FeO-SiO2-3wt%Al2O3-3wt%MgO-8wt%CaO six-element slag system were studied.The melting temperature of slag decreased first and then increased with the increase of Fe2O3 content.The changes of slag viscosity η and viscous flow activation energy Eη with Fe2O3 content can be divided into two situations.When Fe/SiO2=0.8 or 1.0,the slag viscosity η and viscous flow activation energy En decrease first and then increase with the increase of Fe2O3 content.When Fe/SiO2=1.2,the slag viscosity η and viscous flow activation energy Eη gradually increase with the increase of Fe2O3.The analysis of slag structure by FT-IR and Raman showed that Fe2O3 was a network modifier at low Fe/SiO2(0.8,1.0),which reduced the polymerization degree of slag.Under the condition of high Fe/SiO2(1.2),Fe2O3 is the network formation,which enhances the slag polymerization.(3)The effects of MgO on melting temperature,slag viscosity,slag structure and viscous flow activation energy of 12wt%Fe2O3-FeO-SiO2-8wt%CaO-3wt%Al2O3-MgO slag system were studied The results show that the melting temperature,viscosity and viscous flow activation energy of slag decrease first and then increase,with the increase of MgO content from 0 wt%to 9 wt%.When MgO content is low,the degree of polymerization of slag is reduced,and the depolymerization principle conforms to the change rule of non-bridging oxygen number NBO/Si.At high content,due to its higher melting point,the viscosity and activation energy of viscous flow of the slag are increased.