Zero discharge treatment of hydrometallurgical waste acid liquid

The lime neutralization method is used to treat acidic wastewater, so that the residual acid in the wastewater cannot be separated and recovered, the residual acid is not removed, and pollutants such as metal ions cannot be treated. This is not only true for hydrometallurgy, but also for acid wastewater treatment in metal pickling, food, pharmaceutical, non-metallic mineral mining, chemical synthesis and other industries. Therefore, acid separation and recovery of acidic wastewater is the bottleneck of environmental protection. At present, high-concentration acid recovery equipment includes heating evaporation, freezing separation, membrane diffusion separation, etc. However, for the recovery of low-concentration acid liquid, the operating cost is too high, which is also the reason why hydrometallurgy is difficult to promote.
For low-concentration acid wastewater, the current treatment method is mainly lime neutralization. The neutralization method not only destroys recyclable resources, but also uses an equal amount of alkaline substances for treatment, which increases production costs and generates The sludge will prolong the treatment process, increase the investment in treatment equipment, and further increase the company's procurement costs and transportation costs. Hydrometallurgical acidic wastewater is not only acidic but exceeds the standard. It also contains a large amount of metal ions, sometimes accompanied by toxic substances such as arsenic, fluoride, chromium, and cyanide. Under acidic conditions, metal ions are dissolved in the acid solution. After acid recovery, the metal ions are in the neutral solution, which is convenient for subsequent processing, so acid separation and recovery is a wet method. The key to metallurgical acidic wastewater.
Both hydrometallurgical waste acid liquid and acidic wastewater are low-concentration waste acid liquids. There are residual acids and free acids in the acid liquid. The technology for separation and recovery of high-concentration waste acid, heating, evaporation and freezing equipment are not suitable at all. Low concentration waste acid liquid. Due to process differences, product differences, acid types, single acid mixed acid ratios, and residual acid and metal ion impurity ratios in waste acid liquid, hydrometallurgy is divided into two categories: acid separation equipment and acid separation and recovery equipment.
For waste acid liquid with high residual acid content and relatively low metal ion impurity content, acid separation equipment is used. The metal ions in the waste acid liquid are blocked on the filler, and the regenerated acid is directly precipitated and added to the analytical solution, and the metal waste is discharged. liquid.
For waste acid liquid with relatively low residual acid content and high metal ion content, use an acid separation and recovery machine. The residual acid in the waste acid liquid is blocked on the filler, and the metal ions are directly discharged, and water is used for analysis. The liquid is discharged to regenerate the acid.
According to the properties of the waste acid liquid, pretreatment equipment is added according to the pollutant content before and after the acid separation and recovery machine.