Preparation and properties of magnesium silicate cement with magnesium slag extracted lithium from salt lake

Abstract

Using a lithium-extracted magnesium slag (LeMS) as magnesium source in magnesium silicate cement (MSC) preparation has the potential to reduce manufacturing costs and alleviate the environmental impact of LeMS. This study explored the possibility of completely replacing the frequently used light-burned magnesium oxide with LeMS containing magnesium hydroxide. The primary properties of MSC prepared from LeMS were tested and then the hydration products and microstructure were investigated using methods XRD, TG-DTG, FTIR, and SEM. A magnesia-bearing material from calcining LeMS and a brucite-bearing material from hydrated light-burned MgO were used as the magnesia component of MSC compared with LeMS. It is shown that LeMS can be used directly to prepare MSC together with silica fume. The strengths at 3d and 28d of MSC from LeMS were 11.1 MPa and 39.3 MPa respectively, higher than those of MSC from magnesia-bearing and brucite-bearing materials. MSC prepared from LeMS had relatively low apparent density and pH. The main hydration products of MSC prepared from LeMS were M-S-H gels, consistent with the previous research results, and formed much more at earlier age compared to MSC prepared from the other two materials. The relatively homogeneous, less pore microstructure and the higher hydrated degree of MSC prepared from LeMS resulted in higher strength. It is illustrated that LeMS can be used completely as the magnesian component of MSC. It is suggested that the utilization of LeMS in manufacturing MSC is one of the potential ways.