Environmental desulfurization as a tool to improve mine waste management and mine site reclamation

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Mine waste management, including mine tailings, is the most important challenge of mining operations. An upstream-oriented approach would be beneficial for optimal tailings management. Environmental desulfurization, performed by froth flotation, allows recovering most sulfide minerals in the tailings to reduce significantly its reactivity, thus making it chemically suitable as cover material for mine waste reclamation. However, no studies were performed on the effect of desulfurization on tailings hydrogeological properties. Those properties, specifically particle size distribution, may be altered by the desulfurization process and ultimately affect the performance of cover systems made of desulfurized tailings. Furthermore, the usual methods to determine the chemical adequacy of materials for cover systems involve static and kinetic tests, which tend to be inadequate for materials that have low reactivity, and provide very limited information on long term performance of materials as covers. Hydrogeochemical numerical modelling was used to predict the long term behaviour of low reactive waste rock; however more work is required to integrate specific aspects related to low reactive material. Another aspect that deserves investigation is the possibility of using environmental desulfurization to reprocess old tailing ponds to facilitate site reclamation by producing decontaminated tailings that reduce the environmental liability of the site, while at the same time to recover valuable metals that were not recovered in the past.***The proposed research program strives to integrate mineral processing and environmental management to optimize tailings management, though environmental desulfurization as a mean to produce material with the adequate hydrogeological properties to be used in mine site reclamation. The program aims three objectives: 1) to study the effect of environmental desulfurization by flotation on the tailings hydrogeological properties; 2) to simulate using numerical models the hydrogeochemical behaviour of desulfurized tailings; 3) to evaluate the use of environmental desulfurization as a reclamation method for aged tailings. The methodology used to reach these objectives will comprise detailed material characterization (hydrogeological, geochemical, mineralogical), flotation tests, kinetic tests, and numerical modelling. Numerical models, such as Vadose/W and MIN3P will be developed based on laboratory and field data to determine the desulfurization targets to ensure that the desulfurized tailings produced have adequate properties (geochemical and hydrogeological) to be used as a successful cover (monolayer or part of a multilayer system) over the long term. The program will train undergraduate and graduate students, thus providing the Canadian mining industry and research community with much needed experts in mining environment.***