Aluminum oxidation wastewater treatment method and method for preparing ferric phosphate from wastewater

Abstract

The invention relates to an aluminum oxidation wastewater treatment method and a method for preparing ferric phosphate from wastewater. The treatment method comprises the following steps of taking water from mixed discharged phosphoric acid-containing wastewater in an aluminum oxidation process, adding alkali liquor to perform neutralizing adjustment, setting the pH value to 2.4-3.0, adding a certain amount of ferric salt into a secondary stirring tank, adding an oxidizing agent, and performing stirring and mixing in the stirring tank to generate ferric phosphate precipitate; and after separation, obtaining ferric phosphate with relatively high purity, neutralizing clear liquid with lime milk, controlling the pH value to 9.5-10.5, performing secondary precipitation, precipitating residualphosphate radicals in a calcium phosphate mode, meanwhile precipitating aluminum, fluorine and nickel ions in waste liquid synchronously, further performing mud-water separation, adding quantitative sodium hypochlorite into the clear liquid, performing aeration, oxidizing ammonia nitrogen in water, performing blowing-off, and enabling the pH value of outlet water to be 7-9. The final outlet watercan reach the national emission standard through treatment, and phosphate is effectively recovered in a precipitation mode.

Description

technical field [0001] The invention relates to the field of treatment of aluminum oxidation wastewater, in particular to a treatment method for aluminum oxidation wastewater and a method for preparing ferric phosphate from the wastewater. Background technique [0002] Aluminum oxidation is currently the main surface treatment process, which is widely used in various aluminum-plastic packaging products, electronic and electrical product shells, and aluminum profiles. The existing aluminum oxidation surface treatment process requires electrolytic polishing and chemical polishing of the aluminum surface, and then After surface nickel sealing and dyeing, when there is a certain requirement for the quality of surface treatment, high-concentration phosphoric acid is generally used as the main treatment, combined with sulfuric acid and nitric acid for treatment. Due to the active chemical properties of aluminum, a large amount of acid solution is consumed in the whole process, wast...

AI Technical Summary

Problems solved by technology

Due to the high acidity and high concentration of aluminum ions in the wastewater from the aluminum oxidation process, the traditional method will produce a large amount of sludge, and the sludge contains heavy metals such as nickel, chromium, and copper, so the sludge must be disposed of as hazardous solid waste. High treatment costs put heavy pressure on related companies and wastewater treatment

Moreover, with this treatment method, a large amount of high-value phosphoric acid in the sewage cannot be effectively utilized