Recycling method of waste acid from stainless steel acid washing process

An acid cycle and membrane stack technology, applied in the field of metallurgical environmental protection, can solve problems such as unfavorable energy saving, increase production cost, and environmental harm, and achieve the effects of avoiding the deterioration of pickling quality, improving productivity, and reducing production costs.
CN101705495AInactive Publication Date: 2010-05-12TONGJI UNIV +1
0 Cites 12 Cited by

Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
TONGJI UNIV
Publication Date
2010-05-12
Estimated Expiration
Not applicable · inactive patent

Smart Images

  • Figure 1
    Figure 1
  • Figure 2
    Figure 2
  • Figure 3
    Figure 3
Patent Text Reader

Abstract

The invention relates to a recycling method of waste acid from a stainless steel acid washing process, comprising the following steps of: (1) adding water soluble alkali in waste acid to adjust the pH to alkalescence and enable metal ions to generate hydroxide deposition; (2) filtering the hydroxide deposition by adopting a press filtering method, discharging filter cakes outside and collecting the filtrate; and (3) pumping the filtrate into a bipolar-membrane membrane stack, applying electrolysis voltage at the two ends of the membrane stack to generate mixed acid, alkali and dilute salt solution to be respectively discharged through different pipelines. The mixed acid obtained from the method can be reused in an acid washing process, and the alkali can be reused for neutralizing the waste acid in the step (1). Therefore, the invention can realize regeneration of waste acid and the recycling of the alkali, avoid reducing acid washing quality, keep the stable components of acid washing solution and improve the acid washing quality. The invention also has the characteristics of reducing the acid consumption for acid washing, reducing the discharge of acid liquor, reducing the production cost, improving the environment, enhancing the production efficiency and the like.
Need to check novelty before this filing date? Find Prior Art

Description

technical field

[0001] The invention belongs to the field of metallurgy and environmental protection, and in particular relates to a method for recycling stainless steel pickling waste acid. Background technique

[0002] In the stainless steel annealing and pickling line, the iron oxide scale and chromium-poor layer on the surface of the strip are usually removed by pickling, and the surface of the strip is passivated to improve the corrosion resistance of the steel plate. The important pickling is the mixed pickling of nitric acid and hydrofluoric acid. During the pickling process, the acid solution will react with iron, nickel, chromium, etc. in the base metal to form metal salts. As the content of metal ions increases, the free acid components in the acid solution decrease, the activity decreases, and the pickling effect decreases. At the same time, some insoluble substances will accumulate to form a large amount of acid mud, forming a large amount of waste acid. For th...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More