Waste acid recovery method and waste acid recovery device used for treating rolled steel pickling waste liquor

Abstract

The invention discloses a waste acid recovery method used for treating rolled steel pickling waste liquor. The method is used for treating the pickling waste liquor obtained by cleaning rolled steel with hydrochloric acid. By using the method that HCl gas is introduced into the pickling waste liquor and water or diluted hydrochloric acid is added into the pickling waste liquor, iron dichloride tetrahydrate crystals are precipitated from the pickling waste liquor, and a supernate, namely a hydrochloric acid solution capable of being used for rolled steel cleaning, is recycled. According to theobtained waste acid recovery method, the treatment technology that HCl gas is combined with a small amount of water to purify the pickling waste liquor is adopted, zero emission and effective recoveryof the pickling waste liquor are realized, the environmental protection pressure and the operating cost of an enterprise are reduced obviously, simultaneously, the treatment method is simple and convenient in operation, secondary pollution cannot be caused, and current technical defects in treatment of the rolled steel pickling waste liquor are effectively solved.

Description

technical field [0001] The invention relates to the technical field of recovery and treatment of pickling waste liquid, in particular to a waste acid recovery method for treating steel pickling waste liquid, and also relates to a waste acid recovery device used in the waste acid recovery method. Background technique [0002] The pickling treatment of steel is used to remove the oxide scale on the surface of the cold-rolled sheet blank, that is, the hot-rolled sheet. When producing hot-dip galvanized steel pipes, electro-galvanized steel pipes, coated steel pipes or plastic-coated steel pipes, this layer of iron oxide scale must be removed, otherwise it will seriously affect the product quality, and even fail to produce qualified products. Even if there is a thin iron oxide scale before galvanizing, it is impossible to coat a complete and continuous zinc layer. During coating or cladding treatment, if the surface oxide is not removed, it will cause bubbling and reduce the co...

AI Technical Summary

Problems solved by technology

Pickling treatment is an indispensable process in steel production and steel surface treatment. If a large amount of waste acid is not treated and discharged directly, it will cause serious pollution to the environment and greatly pollute water and soil.

[0003] The existing treatment of waste acid usually adopts distillation treatment process or neutralization process. The distillation treatment process mainly uses distillation equipment to heat the waste acid to evaporate dilute hydrochloric acid, thereby precipitating ferrous chloride crystals. Although the distillation treatment process is process Simple, but faced with problems such as high cost investment, complicated operation, and the dilute hydrochloric acid evaporated cannot be processed; the neutralization process mainly uses alkali to neutralize the waste acid, the process is simple and easy, but the management is cumbersome, difficult to control, and the processing cost is high , will also generate a large amount of sludge that is difficult to dispose of, which will easily cause secondary pollution; in addition, the treatment process for waste acid also includes high-temperature cracking, membrane separation, ion exchange and other technologies, but there are great defects and deficiencies in all of them. High consumption, large equipment investment, by-products cannot be processed

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