Study on ozone oxidation for mineral processing wastewater treatment and sludge reduction characteristics

Abstract

With the increasingly stringent environmental management regulations in China, most mineral processing wastewater needs to be recycled and reused. During repeated use, residual chemicals accumulate, leading to an increase in organic matter (characterized by chemical oxygen demand, COD) and often affecting the flotation indicators of polymetallic mineral processing. Therefore, before reusing the wastewater for mineral processing, it needs to be treated. The traditional methods for treating COD in mineral processing wastewater typically require the addition of a large amount of chemicals. While removing COD, they also generate a large amount of sludge, which subsequently increases the high solid waste treatment cost and leads to a serious accumulation of total dissolved solids in the circulating water. These factors hinder the green and sustainable development of the mining industry. This study explores a process for submerged microporous ozone treatment of wastewater from multi metal sulfide flotation, aiming to reduce COD. Laboratory experiments were conducted to investigate the effectiveness of this process in removing COD from wastewater, reducing the generation of sludge, and achieving water recycling. The experimental results indicate that the optimal operating conditions for ozone treatment of the wastewater are an ozone dosage of 0.60-0.75 g/L and a reaction time of 20-25 minutes. This treatment can reduce the influent COD concentration from 145 mg/L to 30-40 mg/L, with a stable removal rate of over 70%. The advantage of this technology is that it does not require the addition of chemicals, produces almost no sludge, and does not generate secondary pollution. After treatment, the water quality is close to fresh production water and suitable for direct reuse in flotation operations. This study provides a technically reliable and economically feasible solution for the effective, low sludge and closed-loop recovery of flotation wastewater in the mining industry, and offers valuable technical insights for promoting green mineral processing practices and reducing solid waste.