Abstract:When the side-blown smelting furnace adopts water-cooled slag-hanging furnace wall, the slag with high thermal conductivity can form a stable slag shell on the surface of the furnace lining to protect and prolong the service life of the furnace lining. Aiming at FeO-CaO-SiO2-PbO-ZnO five-element slag system used for treating jarosite residue and lead-silver slag, the thermal conductivity of furnace slag crust was measured by steady-state plate method, and the microstructure of solid slag crust was analyzed by SEM to explore the influence of slag composition change on thermal conductivity and crystalline mineral phase of slag crust. The results show that adding CaO and SiO2 will increase the thermal conductivity of slag crust, especially the addition of CaO has the most significant effect on slag type. The thermal conductivity of the optimized slag type rises to 17.94 W/(m?K), which is 135% higher than that of the original slag. The phase precipitated at high temperature during the condensation process is melilite, and its melting point and viscosity are significantly lower than that of the original slag. The adjusted slag type is easier to form a stable slag crust, which is beneficial to water cooling and slag hanging to protect the furnace.