Effects of calcination process of Salt Lake magnesium slag on properties of magnesium oxysulfide cement

Abstract

In order to solve the problem of large-scale utilization of magnesium resources in salt lake, low-cost magnesium oxysulfate (MOS) cement was prepared by using magnesia residue as raw material to produce light burning magnesia after washing and calcining. The effects of calcination temperature on the properties of calcined products and the phase and microstructure of MOS cement prepared from the calcined products were studied. The results showed that Mg(OH)2 had been completely decomposing when the calcination temperature was higher than 500°C and calcination time was 2 h. As the calcination temperature reaches 500°C and continues to rise, the activity of MgO gets higher and the crystal size gets larger. It can be seen from the microstructure and XRD that the high temperature is beneficial to the growth of needlestick phase 5Mg(OH)2·MgSO4·7H2O (Phase 5) of the prepared MOS. High calcination temperature results in high porosity.