Mining wastewater---treatment methods (2)

1.Metal replacement method
Metals in wastewater can be recovered using the metal replacement method. In principle, any metal that is more active than the metal to be removed can be used as a displacing agent; in fact, a series of issues such as the source, price, secondary pollution, and subsequent treatment of the displacing agent must be considered. Iron filings are the most commonly used displacing agent.

2.Extraction method
The extraction method uses the different solubility of solutes in water and organic solvents to transfer the solutes in the wastewater into the extraction agent, and then separate the extraction agent from the wastewater. The selected extraction agent should have good selectivity, certain chemical stability, large density difference in water and immiscibility, easy recovery and regeneration, and no secondary pollution. The extraction method is used to treat metal mine wastewater to facilitate the recovery of useful metals in the wastewater, so it is used in the treatment of metal mine wastewater.

3.Ion exchange method
The ionic pollutants in the wastewater can be separated by utilizing the corresponding ion exchange reaction between the solid ion exchanger and the relevant ions in the solution. Ion exchange is carried out in an exchange column filled with ion exchanger. Ion exchangers are divided into two categories: inorganic and organic. Inorganic ion exchangers include natural zeolites, synthetic zeolites, sulfonated coal, etc. Zeolites are utilized in heavy metal wastewater and radioactive wastewater. Organic ion exchangers usually refer to synthetic ion exchange resins. According to the type of exchangeable ions, ion exchange resin can be divided into cation exchange resin and anion cationic resin. Although the cost of ion exchange treatment of wastewater is relatively high, the treated effluent has good quality and can be reused in production, and it is easy to recover useful substances in wastewater. Therefore, it is widely used in the treatment of heavy metal wastewater, rare metal wastewater and precious metal wastewater.