Effect of LiCl·H2O on sintering properties of MgO prepared from natural brine from Qarhan Salt Lake, crystalline bischofite and MgCl2·6H2O(AR) was studied. The results showed that LiCl·H2O of addition exceeded 1 wt% had promoting effect on sintering of magnesia prepared from MgCl2·6H2O(AR). While 1.5 wt% LiCl·H2O was added, the bulk density of magnesia was 3.40 g/cm3, and the relative density was 95.0%. With 0.5 wt% LiCl·H2O, the bulk densities of magnesia prepared from crystalline bischofite and brine were 3.04 and 3.10 g/cm3, and the relative densities increased by 8.4% and 14.8%, respectively. The main mechanism for promoting MgO sintering with LiCl·H2O was that Li2O produced by hydrolysis solubilized in MgO to form solid solutions and oxygen vacancies which were favorable to sintering. The main reasons for promoting sintering of brine magnesia with LiCl·H2O were solid solution and liquid phase sintering, while the main reason was solid solution for magnesia from crystalline bischofite and MgCl2·6H2O(AR).

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Effect of ZrO2 on sintering properties of MgO prepared from natural brine from Qarhan Salt Lake, crystalline bischofite and MgCl2·6H2O(AR) was studied. The results showed that ZrO2 of addition exceeded 1 wt% had promotive effect on sintering of magnesia prepared from MgCl2·6H2O(AR). While 1.5 wt% ZrO2 was added, the bulk density of sample was 3.37 g/cm3, and relative density was 94.1%. With 1 wt% ZrO2, the bulk densities of magnesia prepared from crystalline bischofite and brine were 3.10 and 3.27 g/cm3, and the relative densities increased by 10.0% and 19.6%, respectively. The main reasons for promoting MgO sintering with ZrO2 were that monoclinic phase ZrO2 converted to cubic phase Zr2O and excess ZrO2 reacted with MgO to generate Mg0.13Zr0.87O1.87, which activated lattice and promoted the diffusion of ions during sintering process. In addition, liquid phase sintering was also one of the main reasons for promoting the sintering of brine magnesia.