Closed-Loop Recycling and Upcycling of Waste Pickling Liquid in the Cold Rolling Process

CSC’s cold-rolled steel coils are one of its main products. During the production process, hot-rolled steel coils need to be cleaned with hydrochloric acid to remove surface impurities. However, the waste pickling liquid produced after cleaning contains corrosive and various alloying elements, posing potential threats to the environment.

Waste pickling liquid regeneration technology

Through research, CSC has established a waste pickling liquid regeneration plant, which uses thermal energy to decompose the waste pickling liquid, purify it, and filter out impurities through reduction- oxidation reaction producing by-products such as regenerated acid and iron oxide powder.

The regenerated acid can flow back to the cold rolling production line through the process pipeline, successfully recycling pickling liquid and greatly reducing the cost of purchasing hydrochloric acid and the generation of waste.

Iron oxide powder has an iron content of over 99% and can be supplied to downstream soft magnetic material manufacturers (HIMAG Magnetic Corporation). After molding and sintering, it becomes an iron core with special electromagnetic functions. It is widely used in electronic passive components with high frequency and low voltage output, such as power supply units, electronic sensors, electronic ballasts, and electromagnetic shielding.

▪ CSC also assists partner companies (such as: Chung Hung Steel and China Steel Machinery Corporation) in handling waste pickling liquid and reducing their waste disposal pressure.

▪ CSC has set up an acid regeneration plant in the factory. With the controlled storage capacity of 34 acid storage tanks, it can process approximately 140,000 metric tons of waste pickling liquid every year.