Method for resourceful treatment of iron-containing industrial waste hydrochloric acid

Abstract

The invention discloses a resourceful treatment method of industrial waste hydrochloric acid containing iron, and the resourceful treatment method of the industrial waste hydrochloric acid containing iron is as follows: (1) a salting out agent and the industrial waste hydrochloric acid are added to a deacidification tower, and generated hydrogen chloride gas is escaped by bubbling, stirring, salting out, blowing and desorption; (2) the escaped hydrogen chloride and a bubbling gas are fed under a pressure to an acid pickling tower, and are absorbed and concentrated by water or dilute hydrochloric acid to obtain industrial hydrochloric acid; (3) a produced non condensable gas is conveyed to the deacidification tower and is used as a bubbling gas for circulation; (4) the produced waste liquid is transported to an aeration reactor for reaction to produce ammonium chloride and ferric hydroxide; (5) the solid-liquid mixture generated by the step (4) is transported in turn to a buffer tank and a solid-liquid separator for processing for separation of ferric hydroxide and an ammonium chloride solution; (6) a part of the ammonium chloride solution is transferred to the deacidification tower, the other part of the ammonium chloride solution is decolorized; and (7) the decolorized material is further purified, concentrated and / or crystallized. The method is green, environmental friendly and energy saving.

Description

technical field [0001] The invention belongs to the field of environmental protection and relates to the treatment of industrial iron-containing waste hydrochloric acid, in particular to a method for recycling iron-containing industrial waste hydrochloric acid. Background technique [0002] As a commonly used chemical product, hydrochloric acid is widely used in carbon steel cold rolling, galvanizing and other processes. As a pickling medium, hydrochloric acid reacts with iron oxide on the surface of steel to generate ferrous chloride and ferric chloride and dissolve them in the acid solution. The hydrochloric acid waste liquid produced by this reaction contains about 5% hydrochloric acid and 10-12% ferrous chloride and ferric chloride. If this part of the iron-containing hydrochloric acid waste liquid is directly discharged, it will cause serious environmental damage to the discharge area. pollute. In addition, the waste acid liquid contains ferrous chloride and hydrogen ...

AI Technical Summary

Problems solved by technology

Thermal decomposition method and high temperature hydrolysis method can be divided into roasting method, fluidized bed method, etc. The working principle of these two methods is the same, both of which are to react waste hydrochloric acid containing ferrous chloride with oxygen at high temperature and absorb Concentrate volatilized hydrogen chloride, and the finished products are hydrochloric acid and iron red. The disadvantages are large investment, high operating cost, difficult technology, difficult management and maintenance

The extraction method uses an extract composed of an organic phase for countercurrent extraction, and the method of recycling the extract phase still has high investment and is inconvenient to operate, so it is not suitable

The membrane separation method uses membrane ions to selectively separate iron and acid. The disadvantage is that with the increase of the osmotic pressure of iron ions on both sides of the membrane, a large pressure energy input is required, and it has a great impact on the material and compressive performance of the membrane. High requirements are put forward, and the initial investment and operating costs are relatively high

Precipitation method is to utilize flocculant to flocculate ferrous chloride in waste hydrochloric acid. Although this method utilizes part of ferrous chloride in waste hydrochloric acid, there is still a small part of ferrous chloride in the remaining waste acid solution. This makes the purity level of the product generated by the subsequent waste acid treatment generally not high, which affects the performance of the product

The neutralization method uses alkali to react with waste hydrochloric acid. This is the oldest method for treating pickling waste liquid. However, because hydrogen chloride and ferrous chloride in waste acid liquid have not been utilized, and it is easy to cause secondary pollution, At present, this method is basically no longer used