Method for purifying smelting waste acid

The invention discloses a method for purifying smelting waste acid. The method comprises the following steps: adding a coordination agent into a centralized inflow adjusting pool of waste acid discharged from a sulfuric acid smelting system, stirring uniformly, and filtering the mixture in a filter to further remove insoluble granular impurities; separating dilute acid nearly containing no metal ion and low-acid wastewater through a diffusion dialyzer; adsorbing such residual anion impurities as fluorine and chlorine in the dilute acid through ion exchange resin, concentrating the dilute acid in a multi-effect evaporator and recycling the dilute acid in the sulfuric acid system; further treating the low-acid wastewater to reach the national sewage drainage standard. The method disclosed by the invention can be used for quickly and efficiently separating acid from heavy metal ions in the smelting waste acid, the separated dilute acid can be recycled in a sulfuric acid production procedure after being concentrated, and the method has the advantages of low energy consumption and few residues, and can be used for effectively and comprehensively recycling resources in the waste acid. The wastewater treatment cost is low, and the economic benefit is good. The process is simple, the occupation area of equipment is small and industrialized application is easy to achieve.