Stainless steel cold rolling waste acid purification system

Abstract

The invention belongs to the field of stainless steel processing waste treatment, and relates to a stainless steel cold rolling waste acid purification system. According to the present invention, in stainless steel cold rolling annealing acid washing units, strip steel is required to be subjected to an acid washing treatment to remove oxide scale on the surface of the strip steel; resin adsorption is performed on waste acid generated from acid washing to remove soluble metal ions, wherein the acid washing adopts a mixing acid; the free acid is recycled so as to reduce waste acid emission, reduce production cost, and improve quality of the acid washing product. The acid purification system is an ion exchange system, wherein filtration and resin adsorption are performed on the waste acid liquid to separate iron, nickel and chromium metal salts accumulated in the acid liquid from the acid washing liquid, such that the acid liquid can be reused for stainless steel acid washing. The process principle is the following acid purification system process: carrying out acid washing on the waste acid, adopting a circulation tank, adopting a swirling separator, adopting a filtration unit, adopting a purification system (SAR), and purifying the acid. The waste acid from the acid washing line is filtered through the filtration unit, and then directly enters the acid purification unit (SAR). The free acid water absorbed by the resin bed is substituted by water, and then returns to the acid washing line, and the waste acid enters a wastewater treatment system.

Description

technical field

[0001] The invention belongs to the field of stainless steel processing waste treatment and relates to a stainless steel cold rolling waste acid purification system. 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. Among them, the important pickling is the mixed pickling of nitric acid and hydrofluoric acid. Its main function is to eliminate the chromium-poor layer on the surface of the strip and make the surface of the steel plate whitish and passivated. During the pickling process, the acid solution will react with alloy elements such as Fe and Cr 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 ef...

Examples

Embodiment 1

[0015] Example 1 Purification and recovery of waste acid from stainless steel cold rolling

[0016] 1. The stainless steel cold-rolled annealing and pickling unit pickles the strip to produce waste acid. During the pickling process, the acid solution continuously reacts with alloy elements such as Fe and Cr on the surface of the stainless steel strip to form metal salts.

[0017] 2. The waste acid from the pickling line enters the filter unit after passing through the circulation tank and the cyclone separator.

[0018] 3. Through the filtration system, the solid particles in the waste liquid are removed. Cross-flow microfilter with cyclone separator for direct filtration of hot acids at 60°C.

[0019] 4. The backwash system uses the filtered acid to clean the filter regularly through the backwash pump.

[0020] 5. The waste acid enters the purification system after removing solid impurities through the filtration system.

[0021] 6. In the adsorption stage, the waste acid ...

technical field

[0001] The invention belongs to the field of stainless steel processing waste treatment and relates to a stainless steel cold rolling waste acid purification system. 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. Among them, the important pickling is the mixed pickling of nitric acid and hydrofluoric acid. Its main function is to eliminate the chromium-poor layer on the surface of the strip and make the surface of the steel plate whitish and passivated. During the pickling process, the acid solution will react with alloy elements such as Fe and Cr 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 ef...

Examples

Embodiment 1

[0015] Example 1 Purification and recovery of waste acid from stainless steel cold rolling

[0016] 1. The stainless steel cold-rolled annealing and pickling unit pickles the strip to produce waste acid. During the pickling process, the acid solution continuously reacts with alloy elements such as Fe and Cr on the surface of the stainless steel strip to form metal salts.

[0017] 2. The waste acid from the pickling line enters the filter unit after passing through the circulation tank and the cyclone separator.

[0018] 3. Through the filtration system, the solid particles in the waste liquid are removed. Cross-flow microfilter with cyclone separator for direct filtration of hot acids at 60°C.

[0019] 4. The backwash system uses the filtered acid to clean the filter regularly through the backwash pump.

[0020] 5. The waste acid enters the purification system after removing solid impurities through the filtration system.

[0021] 6. In the adsorption stage, the waste acid ...