Abstract:The passivation treatments are widely used for treating tailings which contain heavy metals with the purpose of preventing the production of acid mine drainage(AMD)from the sources. Therefore, it is very important to find an inexpensive passivator which causes little harm to the environment. In this paper, the authors used H2O2(pH=4)as an oxidant to oxidize the pyrite so as to discuss the passivation effect of bone char on the oxidation and release of heavy metals from pyrite. The results showed that the bone char had a strong neutralization capability, and the addition of bone char(different contents of 0.5 g, 2.5 g, 5 g) resulted in pH increase in the solutions, which were 8.93, 10.01 and 10.42, respectively. The presence of bone char decreased the release of Pb, Zn and Cd, but the release of As increased when the bone char was over 2.5 g. The infrared spectroscopy (FTIR)showed that the characteristic peaks at 420, 563, 603, 1 044, 1 091 cm-1 belong to vibration of PO43- produced by the dissolution of the bone char. XRD analysis suggested that the secondary mineral phases on the surface of the pyrite were graftonite and phosphogartrellite, which played an important role in heavy metals immobilization. As a passivating agent, bone char is most suitable for treating pyrite tailings which contain heavy metals.