Strip steel pickling device and method

Abstract

The invention relates to a strip steel pickling device and method. The device comprises a plurality of pickling tanks which are sequentially arranged along a conveying direction of strip steel; a plurality of acid tanks which are respectively arranged below the pickling tanks to form a plurality of acid liquor circulating systems with the pickling tanks through respective circulating pumps; an online standby acid tank which is in fluid communication with an inlet acid liquor circulating system and is used for removing metal ions in the acid liquor and regenerating the acid liquor into a new acid; an agent adding system which is used for adding polyatomic acid and a flocculating agent into the online standby acid tank; a drying system which is used for drying the acid mud; a condensing system which is used for condensing and recycling the acid mist discharged by the drying system; and an oxidability regulation and control system which is used for controlling the activity of the acid liquor of each acid liquor circulation system. According to the method, the polybasic acid and the flocculating agent are added for online precipitation and purification of the acid liquor, the content of metal ions in the acid liquor is controlled, and meanwhile, composition of the acid liquor is regulated and controlled, so that the activity of the acid liquor is improved, and therefore, the descaling efficiency is improved, high-surface-quality strip steel is obtained, and the consumption of new acid can be reduced.

Description

technical field [0001] The invention relates to the technical field of strip steel surface cleaning, in particular to a strip steel pickling device and method. Background technique [0002] The surface quality of strip steel is one of the key factors affecting the improvement of product performance. At present, strong acid pickling is used to remove the oxide scale on the surface of the steel strip. The pickling takes place in a multi-stage series of acid tanks. The temperature of the acid solution is generally 40-85°C. As the pickling progresses, the content of metal ions in the acid solution gradually increases. Reduce the activity of pickling solution. For the conventional continuous pickling process of carbon steel, the content of hydrochloric acid in the first acid tank is 40-60g / L, the content of metal ion Fe2+ is 100-120g / L, and the content of Fe3+ is 5-10g / L. When the concentration is lower than or close to this concentration, the pickling efficiency is significant...

AI Technical Summary

Problems solved by technology

The above process can recover high-purity hydrochloric acid, but at the same time, it needs to configure an acid regeneration treatment station, and the operation energy consumption is also high

In addition, strip steel contains components that are insoluble in acid solution, such as silicon, boron, manganese and other elements that form insoluble acid sludge in acid solution, which will block heat exchangers and pipelines and affect the efficiency of acid regeneration, so it needs to be removed urgently

If the pickling solution purification only removes metal ions and recovers free acid, and does not consider the removal of insoluble silicon, boron, manganese and other elements in a targeted manner, high-purity reuse of pickling cannot be achieved, and it is difficult to ensure the quality of regenerated acid. It is difficult to ensure the quality of pickling

The composition of the acid solution will also significantly affect the pickling efficiency and the quality of the board surface. The current conventional practice is to add an organic compound pickling accelerator to improve the pickling efficiency, but the cost is high, and it will cause the COD of the acid regeneration wastewater to exceed the standard

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