Characterization and evaluation of gold mill tailings as an additive in cement-stabilized products

Abstract Gold mill tailings (GMT) are waste from gold mill processing plants usually collected and stored in tailings storage facilities (TSF) and left for years in many abandoned mines in the world. GMT is in large amounts and contains high concentrations of chemicals and compounds that may harm human lives and the ecosystem if not well-maintained. A characterization study is conducted on GMT from a small-scale mill processing plant in Agusan del Sur, Philippines, and its potential utilization as an additive to sand and cement in making cement-stabilized products is also evaluated. The elemental and oxide composition, the presence of free and total cyanide, and particle size analysis were determined. Different proportions of gold mill tailings, cement, and sand were prepared and tested for compressive strength and water absorption. The results showed that the GMT contained some potentially valuable elements like tin, zinc, and europium. GMT also contains potentially hazardous elements like lead (663ppm), arsenic (157ppm), and mercury (17ppm). The free cyanide in the effluent is also found at 1.9 ppm. These elements and compounds are potentially hazardous in case of tailings seepage or overflow to groundwater and neighboring agricultural lands. The evaluation of cement-stabilized samples shows that the GMT from the study area can be utilized as an additive to cement and sand in the production of cement-stabilized products however it must be properly treated and handled to ensure the safety of workers. The TCLP result showed that the product is non-toxic and non-reactive. The construction and proper maintenance of a TSF for small-scale gold milling plants in the study area is recommended to prevent environmental, health, and safety risks.