Experimental research on the utilization of gold mine tailings in magnesium potassium phosphate cement

Gold mine tailings (GT) are fine-grained ore processing wastes with a high variety of minerals and metals. Storing large amounts of GT in impoundments results in a waste of resources and in several cases environmental pollution. Magnesium potassium phosphate cement (MKPC) is green-sustainable cement made by magnesia (MgO, M) and KH2PO4, which can be used to effectively immobilize radioactive and hazardous wastes elements through mineralization and microencapsulation. This paper aimed at the utilization of GT in MKPC.GT was incorporated into MKPC through two different pathways, either partially replacing M or the binder (both M and KH2PO4). The influences of GT on MKPC were evaluated through workability, compressive strength, and microstructure. It was found that the partial replacement of M by GT can result in better workability, denser microstructure and higher late-stage compressive strength. The incorporation of GT generates new types of hydrates in the structure. The compressive strength was improved by a factor of 114.94% when an additional 10% M was replaced by GT; when the displacement of GT was 30%, it yielded a compressive strength approaching the basic group. Therefore, the partial replacement of M with GT was suitable to incorporate GT into MKPC in order to achieve the utilization of GT, reduce the cost and improve the mechanical properties of MKPC