Mg recovery from salt lake brine into forsterite refractory materials via precipitation-calcination process
(1. National Engineering Research Center for Comprehensive Utilization of Salt Lake Resources, School of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China;
2. Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources, School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China)
2. Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources, School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China)
Abstract: Li/Mg separation and magnesium recovery as a high-value forsterite refractory material from the salt lake were investigated via the precipitation-calcination process. The combined Na2SiO3 and NaOH precipitants were applied for Li/Mg precipitation separation from salt lake brine and magnesium precipitates could be produced with various MgO/SiO2 molar ratios. It is demonstrated that the magnesium precipitates were mainly composed of accumulative amorphous magnesium silicate and magnesium hydroxide, with more than 62% of mass residual at 1400 °C. The high- temperature sintering experiments showed that when the Mg/Na2SiO3/NaOH molar ratio was 1:0.6:0.8, the magnesium precipitates could be prepared into a high-quality refractory material under the conditions of 1350 °C and 210 min, with the refractoriness of higher than 1800 °C, compressive strength of 190.73 MPa, bulk density of 2.53 g/cm3, and apparent porosity of 5.94%. The prepared refractory materials mainly contained forsterite, with a minor enstatite phase.
Key words: salt lake brine; combined precipitants; Li/Mg precipitation separation; magnesium precipitates; forsterite refractory material