Viscosities of FenO-MgO-SiO2 and FenO-MgO-CaO-SiO2 slags
(School of Metallurgical Science and Engineering,
Central South University, Changsha 410083, China)
Central South University, Changsha 410083, China)
Abstract: The viscosities of molten FenO-MgO-SiO2 and FenO-MgO-CaO-SiO2 semi-synthetic slags for nickel flash smelting were mearured in the temperature range of 1200-1450℃ by use of a rotational viscometer. The mass ratio of Fe to SiO2 was fixed at 1.2, calcium oxide and magnesium oxide contents varied in the range of 2%-8% and 9%-12%(mass fraction), respectively. The results show that silicate anions become smaller by increasing CaO content, which results in the viscosity decrease of slag. In the case of addition of MgO the viscosity behaviour is complicated. When MgO content is less than 11%, the viscosity increases with the increase of MgO at all temperatures tested . However, when the MgO content is more than 11%, the viscosity decreases slightly for FenO-MgO-CaO-SiO2 system. At higher MgO contents, low-viscosity slags can be obtained by adding CaO. As for a given composition, the viscosity decreased with increasing temperature .The higher the temperature, the more MgO can be added before saturation. The effect of Fe3O4 on the viscosity is quite significant. The viscosity of slag increases to 300mPa·s at 1300℃ when Fe3O4 content varied from 2.84% to 9.53%. The viscosity values are expressed as the functions of temperature and composition. A comparison between FenO-MgO-SiO2 and FenO-MgO-CaO-SiO2 systems are also given.
Key words: nickel flash smelting; high-magnesium slag; viscosity