At a milling speed of 500 rpm, and BPR 12, the leaching concentrations of Pb, Cu and Zn decreased with increasing milling time as shown in Fig. 2.The leaching concentrations of Pb, Cu and Zn in untreated soil were 13.92 mg·L −1, 2.71 mg·L −1, and 114.31 mg·L −1, which were 273 times, 2.6 times, and 113 times higher than the Class III level of the Chinese Surface Water Environmental ...