Treatment and prevention of pollutants in the wastewater from a scheelite and fluorite processing plant

Abstract

Mineral processing wastewater contains high levels of chemical oxygen demand (COD), suspended solids (SS) and heavy metal ions, and its substandard discharge will pose a threat to the ecological environment and human health. In this study, a combined method of coagulation and Fenton oxidation was used to remove pollutants from scheelite and fluorite processing wastewater. The experimental results showed that the overall removal rates of COD, SS, Pb2+ and Zn2+ from the wastewater samples reached 88.41 %, 99.73 %, 99.09 % and 99.31 %, respectively, after stepwise treatment with poly ferric sulfate (PFS) coagulation and Fenton oxidation. The main contributors of COD in the wastewater samples were sodium oleate (NaOL) and benzohydroxamic acid (BHA). The maximum COD removal by PFS coagulation was >90 % for NaOL solution, but <45 % for BHA solution. The COD removal effect of Fenton process on NaOL solution was also better than that of BHA. This indicated that the removal effect of COD was not only related to the experimental conditions but also to the structure of organic compounds. Based on the above research, a monitoring and management system of pollutants was established, and the effective removal of pollutants was confirmed by industrial tests in a plant. This study provides a certain theoretical basis and technical support for the efficient treatment of mineral processing wastewater and is of great significance for the protection of the ecological environment around the mine.