Grant: Collaborative Research and Development Grants

Water is a process medium in mineral processing. The challenge for reclaim water is to treat the process water in such a way that chemicals used in water treatment have a negligible negative impact, if not a positive synergistic effect, on mineral recovery in flotation. Base metal processing operations often treat process tailings and acid mine drainage using a lime-based water treatment process (WTP). When a recycle water stream with a high concentration of calcium (Ca2+) and sulphate (SO4 2-) ions is incorporated in the process, potential precipitation of gypsum on both sulfide minerals and silica gangues makes both mineral surfaces of the same surface characteristics, thus decreasing the selectivity and flotation recovery. A better understanding of the determinants and the nature of precipitation through the controlled nucleation/precipitation and crystallization of gypsum will enhance the formation of precipitates only on gangue minerals for a better flotation performance of valuable minerals while minimizing environmental impacts. The key themes of this proposal are to determine whether functionalized gypsum seed particles can be used to improve the gypsum crystallization rates in the water treatment plant (WTP), and how to achieve selective precipitation of gypsum to gangue minerals. The total dissolved solids (TDS) concentrations in the treated water should be close to or less than gypsum saturation level. The ability to achieve this concentration will enable more treated water to be recycled from operations and avoid scaling that occurs in the concentrators. The selective precipitation will result in higher recoveries and selectivities in the flotation. Our target operation is Teck's Red Dog Operation; however the methodologies are applicable to all other mineral processing plants.