Study on the Hydrothermal Solidification of Low grade Magnesite Tailings

With a purpose of realizing the resourced utilization of magnesite tailings,a feasible way is proposed in this work with the combination of high-temperature calcination and hydrothermal solidification.The low-grade magnesite was preliminarily transferred from MgCO3 into MgO with improved activity,which subsequently combined with silica fume (strengthening additive) under the atmosphere of saturated steam in elevated temperature.A remarkable strength was obtained from the hydrothermally solidified specimens,which should be attributed to the generation and aggregation of magnesium silicate hydrate in high crystallity,i.e.talc.After a systematic investigations of the preparation process,the conditions for the high-temperature calcination and hydrothermal solidification were suggested to maximize the mechanical strength up to 16.75 MPa in the as-prepared specimen,i.e.the calcination was carried out at 800℃ for 1.0 h,while the MgO content of 50 % and water content of 40 % were controlled simultaneously in the starting materials,and the hydrothermal solidification was performed at 200℃ for 6 h.The results must be helpful to accelerate the recycled utilization of such industrial wastes as low-grade magnesite,brucite tailings or boron slurry etc.