New dephosphorizing process for metal salt containing waste phosphoric acid

Abstract

The invention relates to a new dephosphorizing process for metal salt containing waste phosphoric acid. The process comprises the following steps: (1) carrying out neutralization with lime, so as to obtain calcium phosphate precipitates; (2) carrying out preliminary filtration, so as to filter out solid or colloidal particles from waste liquor; and (3) carrying out adsorption dephosphorizing on residual phosphate radicals in the waste liquor by using chloro-type strongly-alkaline anion exchange resin, wherein effluent is a phosphorus-free solution which can be directly discharged or be subjected to conventional wastewater treatment, and a phosphorus-containing salt solution which is desorbed by an ion-exchange resin bed can be refluxed to last step again for circulation. According to the process, the waste phosphoric acid is treated by a chemical ion exchange method instead of environment-sensitive biological technologies, so that phosphorus can be effectively removed from waste phosphoric acid liquor, the content of phosphorus in the wastewater can reach national emission standards, and the treatment result is very stable; and a byproduct, i.e., calcium phosphate of the process can be recycled as a phosphate fertilizer.

Description

Technical field [0001] The invention relates to the technical field of wastewater treatment, in particular to a new process for removing phosphorus from waste phosphoric acid containing metal salts. Background technique [0002] At present, certain chemical industries, such as aluminum electrolytic capacitor aluminum foil, steel and other metal surface treatment processes, produce a large amount of waste phosphoric acid. Some of the traditional methods of processing these waste phosphoric acid are directly discharged, which seriously pollutes the environment; some are neutralized with lime, which not only increases the processing cost but also produces a large amount of sludge, the solution still contains a small amount of phosphorus ions, and in recent years, my country has strictly protected water resources. The phosphorous emission standard is regulated. This method of neutralizing with lime makes the phosphorous emission unable to meet the new environmental protection standard...

AI Technical Summary

Problems solved by technology

Some of the traditional methods of treating these waste phosphoric acids are directly discharged, which seriously pollutes the environment; some are neutralized with lime, which not only increases the treatment cost but also produces a large amount of sludge. Phosphorus discharge standards are regulated, and this method of neutralizing with lime, phosphorus discharge can no longer meet the new environmental protection standards

Another approach is to use biological treatment methods, but this also has various disadvantages

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