Method for reclaiming sulfuric ammonium and ferric oxide from sulfuric acid pickling waste fluid

Abstract

The method for recovering ammonium sulfate and iron oxide from sulfuric acid pickling waste liquor belongs to the field of environmental protection. It is difficult to separate the precipitate legally formed in common ammonia from the ammonium sulfate solution, and the produced ammonium sulfate contains many impurities, poor quality, and low ammonia recovery rate. The pickling waste liquid is filtered through the primary filter to remove solid particle impurities, and enters the neutralization reactor to undergo neutralization reaction with ammonia liquid and ammonia gas. When the reaction pH value is 8 to 11.5, a precipitate is formed; an organic flocculant is added in the neutralization reaction stage , into the precipitation filter for filtration and separation; the filtrate is heated and then filtered to remove impurities; the filter residue is discharged to the precipitation filter, and the secondary filtrate is evaporated and crystallized in the evaporation crystallizer to obtain ammonium sulfate with white color; The rinser is rinsed with ammonia liquid, and the leached ammonia liquid is used as the ammonia liquid feed of the neutralization reactor; after the rinse, the filter cake is heated and dried by the dryer, and the ammonia gas is evaporated and returned to the neutralization reactor. The precipitation and the ammonium sulfate solution of the invention are easy to separate, and the ammonium sulfate produced contains less impurities and has a high ammonia recovery rate.

Description

Technical field: [0001] The invention relates to a technology for pollution control and resource reuse of industrial sulfuric acid pickling waste liquid, which belongs to the category of environmental protection. Background technique: [0002] In the iron and steel processing industry, pickling is used to remove iron oxide on the surface before phosphating, welding and other steel treatment processes. During pickling, sulfuric acid reacts with iron oxide and metallic iron on the surface, mainly producing ferrous sulfate. As the reaction progresses, the ferrous sulfate content increases and the acidity of the pickling solution decreases. When the sulfuric acid concentration of the pickling solution was reduced to 2-3%, the pickling solution must be renewed, and the ferrous sulfate weight percentage at this moment was about 20%. The discharged pickling waste liquid must be treated. The common treatment methods are: [0003] 1. Lime is legal. Add lime powder to the pickling...

AI Technical Summary

Problems solved by technology

This type of method has a good application prospect, but due to the difficulty in separating the iron oxide precipitate and ammonium sulfate solution generated in the previous process, and due to the low purity and poor quality of the obtained ammonium sulfate, this type of technology still needs to be improved

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