Acid generation potential and environmental risk of waste rock in copper sulfide heap

The waste rocks in copper sulfide heap leaching site contain sulfur and will produce acid. Through ABA acid-base estimation method, ANC of samples at different depths were negative, with an average of −5.76, APR (Acid Potential Ratio, ANC/MPA) 20 kg·t−1(According H2SO4). By the NAG (Net Acid Yield) method, the result of NAG-pH <4.5 is obtained. The results indicate that the waste rocks at different depths of the heap leaching site have a certain degree of efflorescence, potential acid production and acidification risk. The 38 weeks of simulated weathering and leaching test results show that sulfide minerals such as pyrite were oxidized to produce acid and release metal ions, and the copper and iron in the slacking slag are mainly sulfide, which still pose a certain risk to the environment. A series of measures such as isolation and inhibition of acid production, neutralization and ecological restoration can be taken in the final pile leaching site with anti-leakage pad to improve the stability of the environment, reduce the amount of acid wastewater production and reduce the impact on the environment.