Process for recovering heavy metallic salt and inorganic acid in pickling waste liquid

Abstract

The invention relates to a process for separating and recovering heavy metallic salt and inorganic acid in pickling waste liquid by a membrane method, which comprises the following concrete steps: filtering and removing solid suspended substances in pickling waste liquid through an inorganic ceramic membrane; separating acid from salt in the ceramic membrane penetrating liquid through diffusion dialysis; and heating the dialysis liquid of a diffusion dialyzer, then introducing the dialysis liquid into a nanofiltration membrane, and cooling and crystallizing the concentrated liquid of a nanofiltration device and then centrifuging the crystal of the concentrated liquid to obtain iron salt, wherein the penetrating liquid of the nanofiltration device passes through a reverse osmosis membrane device, the concentrated liquid of the reverse osmosis device returns to a pickling section, and the water discharged from the reverse osmosis device enters a diffusion dialysis section for recycling. The invention has the characteristics that the pickling waste liquid is completely used as resources, the recovery process is simple, the recovery ratio of metallic salt and acid is high, and water is recycled. The process of the invention can be coupled with various pickling sections to realize continuous and stable automated operation, and the supplemented acid amount can be quantitatively controlled according to the acid amount consumed by the crystallized metallic salt.

Description

technical field [0001] The invention relates to the field of resource utilization of waste water, in particular to a process for separating and recovering heavy metal salts and inorganic acids in pickling waste liquid by using a membrane method, so that the treated pickling waste acid and inorganic acid neutralized metal salts can be comprehensively utilized, reducing waste water disposal. Background technique [0002] In the process of industrial production, mining and smelting (such as iron and steel industry, titanium dioxide industry, hydrometallurgy industry, titanium industry, electroplating industry, rare earth industry, wood saccharification industry, gold mining and non-ferrous metal smelting industry, etc.), often Use inorganic acids (such as sulfuric acid, hydrochloric acid, nitric acid, hydrofluoric acid, etc.) to clean metal surfaces or dissolve ores. A large amount of spent acid solution containing various metal ions is then produced. Taking the iron and stee...

AI Technical Summary

Problems solved by technology

The problems of this method are: resource recycling is incomplete, the dialysate in the diffusion dialysis and the concentrated solution in the nanofiltration process are not treated so that the metal salt cannot be recovered; the acid is concentrated by nanofiltration and reverse osmosis, which is relatively difficult A high concentration of acid will greatly reduce the service life of the membrane and increase the treatment cost; if the pickling waste liquid is a mixed acid system, the use of the purified and concentrated acid will be greatly limited, and its applicability will be greatly restricted. limit

[0006] To sum up, there is currently a lack of a process for the comprehensive treatment of metal waste acid solution, which can achieve the purpose of separate recovery of metal and acid without secondary pollution and can be well coupled with the original process

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