Sustainable Mining and Metallurgy

A large amount of contaminated acid and acidic wastewater are produced in the operation of each process of a copper smelting enterprise. The contaminated acid has the characteristics of high acidity and high arsenic concentration, which is easy to cause harm to the environment and human body. In this paper, the combined process of “two-stage sulfidation + two-stage neutralization” was used to treat the contaminated acid and acidic wastewater. The two-stage sulfidation used sodium hydrosulfide precipitation to remove heavy metal elements such as arsenic and copper in the contaminated acid. The two-stage neutralization used limestone to neutralize the acid in the contaminated acid, and then used calcium carbide slag and iron salt to neutralize the heavy metal ions. After treatment, the arsenic content was reduced from 8~14g/L to less than 0.5mg/L, and the H₂SO₄ content was reduced from 125g/L to 0.5mg/L, which met the requirements of national standard and could meet the water requirements of other processes in the plant area, and achieve the goal of “zero discharge” for the recycling of contaminated acid and acid wastewater.