Drying and oxidation of surface-disposed paste tailings.

摘要

Surface deposition of paste tailings has been used at the Bulyanhulu Gold Mine in Tanzania since 2001, but little is known about sulphide mineral oxidation in the paste storage facility. The rate of pyrite oxidation in a freshly deposited layer of paste depends on the rate of oxygen diffusion and the reaction kinetics. A coupled soil-atmosphere evaporation model (SoilCover) and a 1-D diffusive transport model (POLLUTE) were used to predict the extent of drying, oxygen ingress and sulphide consumption in layers of paste tailings. The results of the models agreed well with experimental results from small-scale and column laboratory tests, regardless of crack formation. The models were then used to develop a conservative estimate of pyrite oxidation at Bulyanhulu. Based on the results of the laboratory testing program and model simulations, it was concluded that acid drainage conditions could occur in the Bulyanhulu tailings storage facility.