Once the metal blank for enamel is corroded, even if the area is small or low, it will seriously affect the quality of the enamel product. Therefore, the rusty iron blank needs to be thoroughly derusted. Derusting is inseparable from pickling. It’s basic operations and requirements are very important.

Pickling is a chemical reaction between the acid solution and the oxide layer on the surface of the iron billet to dissolve iron oxide and rust. It can also peel off the loose oxide scale through the precipitation of hydrogen. The choice of acid is sulfuric acid and hydrochloric acid. The rust removal principle of sulfuric acid is to produce hydrogen during the pickling process to mechanically strip the metal iron, while the rust removal principle of hydrochloric acid is to dissolve and remove the rust quickly, but the consumption of acid is relatively large. Need to be changed frequently.

The pickling operation needs to strictly follow the pickling industrial process to control the concentration, temperature and pickling time of the acid solution. Specific steps are as follows:

1. Put the corroded iron blanks into the basket after degreasing, and slowly immerse them in the pickling tank;

2. During the pickling process, the iron billet must be completely immersed in the solution, shake the basket up and down, left and right, so that every surface of the iron billet can come into contact with the pickling solution;

3. After removing the rust, pay attention to the tilt when removing the basket, drain the acid and put it into the clean water tank, and thoroughly wash the remaining liquid on the surface of the iron billet with water.

Here are a few basic things to note:

1. The condition of acid solution: After pickling, pay attention to the consumption of acid solution and replenish it regularly. If the acid solution turns green, it means that the content of ferrous sulfate has exceeded the standard and needs to be replaced;

2. Once the rust removal is completed, immediately stop pickling to reduce the hydrogen adsorption of the iron billet and prevent the occurrence of scale explosion;

3. Grasp the relationship between the temperature of the acid solution, the concentration of the acid solution and the pickling time. Only reasonable control can achieve a good pickling effect.