Comprehensive treatment and utilization method of waste acid with high zinc content

Abstract

The invention relates to a method for comprehensive treatment and utilization of high-zinc-content waste acid. By reasonably designing process steps and reaction agents of the method for comprehensive treatment and utilization of the high-zinc-content waste acid, effective separation, recycling and reutilization of iron and zinc are achieved, iron and zinc resource waste is avoided, a by-product industrial calcium chloride solution having a wide industrial application value and meeting the national quality standard is also obtained, comprehensive treatment and utilization of the high-zinc-content waste acid is successfully achieved, and the method is simple in process, lower in cost, green and environmentally friendly.

Description

technical field [0001] The invention relates to the field of industrial wastewater treatment, in particular to a method for comprehensive treatment and utilization of high-zinc-containing waste acid. Background technique [0002] At present, the waste acid with high zinc content mainly comes from galvanizing plants. On the one hand, the hot-dip galvanizing process is an important means to delay the corrosion of steel. Before the hot-dip galvanizing starts, the steel surface needs to be pickled, and the rust and oxide film on the steel surface should be washed away with hydrochloric acid. Good pickling effect cannot be achieved and it becomes waste liquid. On the other hand, unqualified galvanized steel needs to backwash the galvanized layer on the surface with hydrochloric acid, that is, zinc stripping treatment. Similarly, when the hydrochloric acid content is reduced to a certain concentration, it cannot continue Therefore, the high zinc-containing waste acid from the gal...

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Problems solved by technology

[0003] For example, Chinese patent CN105132932A publicly reported a method for recycling waste acid solution from backwashing of galvanized parts, which uses ammonia water to adjust the pH value of the solution to make Fe 3+ with Fe(OH) 3 After the form is precipitated and separated, it is used for sintering and ironmaking, containing NH 4+ and Zn 2+ The filtrate is compounded to obtain a flux, which is returned to the hot-dip galvanizing process, but this method does not consider NH 4+ The final recovery and the investment cost of selecting ammonia corrosion-resistant equipment

[0004] As another example, Chinese patent CN102560517A discloses a comprehensive utilization method of zinc-containing waste hydrochloric acid, which adopts strong basic anion exchange resin to recover ZnCl 2 , used as a by-product of flux after being eluted by the regenerant, and the solution after the resin adsorption treatment is compounded and concentrated with industrial hydrochloric acid and then returned to the hot-dip galvanizing process for use. However, the ion exchange resin is expensive and the operation is complicated, resulting in relatively high production costs. High, and difficult to handle Zn 2+ High zinc waste acid with a mass concentration of 3% to 20% is not conducive to industrial application and promotion

[0005] As another example, Chinese patent CN103539302A publicly reported a treatment method for waste acid containing zinc and iron, which mainly uses reducing iron powder, zinc powder or a mixture of the two to replace heavy metal ions in waste acid to achieve the purpose of purifying waste acid. Utilizing the volatility of hydrochloric acid at a higher temperature, the hydrochloric acid is replaced with concentrated sulfuric acid, so that the solution is changed from the hydrochloric acid system to the sulfuric acid system, thereby obtaining the target product. This method does not consider the treatment of the acid consumption stage, and the process is more complicated. Moreover, the exothermicity of the reaction and the volatility of hydrochloric acid are also unfavorable for the recovery of hydrogen chloride gas.

[0006] It can be seen that in the comprehensive treatment and utilization method of zinc-containing waste acid disclosed in the above-mentioned patent, there are a series of problems such as complex process, high cost and inability to handle high zinc-containing waste acid.

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