Pickling Steel craft Disadvantages

Pickling Steel craft Disadvantages-The pickling treatment of steel is widely used in the removal of iron oxide scale on the surface of cold-rolled sheet blanks, that is, hot-rolled sheets.

Pickling Steel

Other surface pretreatment before hot-dip plating and electroplating; surface treatment of annealed steel such as pipes, profiles, wires, etc. before cold-drawing;

Similar treatment in special steel production. Pickling is still an indispensable process in steel production and steel surface treatment. However, the adoption of the steel pickling process also brings some problems as follows:

(1) Large consumption of steel materials and acid
In the process of pickling, some of the iron sheets are mainly removed by the chemical reaction of acid and iron sheets to dissolve the corresponding metal oxides. Some, such as the use of sulfuric acid for steel pickling, the iron oxide scale is also removed by means of the stripping action of hydrogen bubbles generated by the chemical reaction between the acid and the steel. Therefore, in the pickling process, it is inevitable to consume a large amount of acid. Although the use of pickling inhibitors in pickling can reduce the metal consumption of steel, a considerable amount of metallic iron is still lost.

(2) May reduce the physical properties of steel
During the pickling process, a chemical reaction occurs between metallic iron and acid and hydrogen gas is produced. Since the chemical potential of hydrogen in the pickling solution is higher than that of the steel being pickled, the generated hydrogen will penetrate into the steel and accumulate to cause hydrogen embrittlement, thereby affecting the mechanical properties of the steel or subsequent processing.

(3) It will bring a series of environmental pollution problems
The pickling process is used for surface treatment of steel or parts. Due to the different types of steel, product specifications and production scales, there are great differences in production equipment and production environment. For example, the sealing of the pickling tank, the corrosion of production equipment, the ventilation and exhaust of the pickling workshop, the discharge and treatment of acid mist, and the treatment and discharge of sewage, etc., the treatment methods and treatment levels vary greatly. As a result, it will bring many environmental protection problems, which need to be dealt with and solved one by one.

(4) Disposal of waste acid and iron salt
The pickling of iron and steel consumes a large amount of metallic iron and also produces a large amount of waste acid solution and the corresponding acid and iron oxide or the resulting iron salt solution. In order to recover and utilize these waste acids and iron salts, a large investment is required to build corresponding recovery and treatment equipment. Especially for some small, small-batch steel parts for pickling treatment, it is often difficult to concentrate the pickling waste liquid for treatment. Once the direct discharge occurs, it will cause serious pollution to the environment.

related information:

Pickling Steel Basic principles

Color Coated Steel

Hot-rolled Steel