When copper smelting, viscosity is one of the important properties of slag and it influence the separation and release of slag and matte,heat transfer, etc.It requires low slag viscosity, good liquidity in the production,it is good for operation and the separation of slag and matte. 

    Viscosity is influenced by the following two factors: 1. The degree of overheating.When slag temperature is 100-200 k higher than the melting point, the viscosity is lower, liquidity is good. 2. The structure of slag.Slag is ionic structure, it's consists of cationic such as Fe2+、Ca2+、Mg2+and complex anion such as SixO y2-,AlxOy y2-.The anion size is small,structure is simple, and AlxOy content is smaller, so the viscosity is decided by AlxOyy2- that with big size and complex structure.AlxOy y2- ion size and structure change along the SiO2 content or O: Si ratio. 

    Slag composition SiO2, Al2O3 is also called the network structure agent, therefore, in the slag composition, with the increase of SiO2, its structure is more complex, viscosity increases.FeO and MgO are called network disintegration agent, with O2- into SixOy2- anion, will collapse complex ion to simple anionic , reduce the viscosity. 

    The factors influencing slag viscosity mainly is SiO2, FeO content and temperature.