Wastewater treatment using DAF for process water reuse in apatite flotation

Successful mineral processing depends largely on the adequate consideration of its interactions with water. Considering water scarcity and the cost for the use of a fresh water, the mineral industry has been looking for viable alternatives for the reuse of process water. However, recycling water from tailings dams can contain large amounts of dissolved species, particulate matter, organic matter from residual reagents, etc., which negatively affect the ore concentration stage. In this work, the deleterious effects of calcium, magnesium, and phosphorus ions, present in recycling water, on the apatite flotation performance have been quantified. It also investigated the use of dissolved air flotation (DAF), associated with coagulation/flocculation treatment to remove most of the contaminants present in the water. Effect of pH on this combined process of wastewater treatment has also been investigated. Removal efficiencies of calcium, magnesium, and phosphate ions and also turbidity have been measured. Water from a tailing dam of an apatite processing industry has been treated by this technique and the produced water used in the flotation of apatite in column. Results have shown that the use of recycling water after the wastewater treatment proposed in this work led to a good performance of apatite flotation, leading to recovery (80.5%) and grade (31.2%) of P2O5 highest than minimum acceptable in this industry.