Impact of Recirculating Mining Process Water on the Flotation Performance of a Sedimentary Phosphate Ore

Water is one of the scarce resources in the world and the mining industry like many other sectors is expected to discretionally utilise this resource sustainably. It was on the premise of adding to the body of knowledge related to water sustainability and flotation performance that an investigation was prompted to evaluate the impact of recirculating mining process water on the flotation performance of a sedimentary phosphate ore. A series of flotation locked cycle tests were conducted with the objective to simulate recycling process water, which by default modifies the water chemistry and influences flotation performance. The laboratory flotation results showed that recycling process water in the laboratory scale did not show significantly noticeable influence on P₂O₅ grade and recovery performance. A saleable product of 33.27% P₂O₅ grade at reasonable average recovery of 65% was achievable. Water analyses revealed that there was an increase in total dissolved solids [452 to 846mg/L], electrical conductivity [662 µm/cm to 1025 µm/cm], CaCO₃ [146 to 304mg/L], sodium [57.7 to 76.6mg/L], chloride [100.7 to 109.7mg/L] and magnesium [10.4 to12.6mg/L] after circulating the process water for 15 cycles. The results achieved however confirmed the importance of water quality and understanding process water chemistry in flotation processes. The compounding salts and inorganic elements in the water necessitate the need for water clarifiers for process water prior to being recycled to the flotation process.