Inhibition of sulfide mineral oxidation by surface coating agents: batch and field studies.

Abstract The potential of several surface coating agents to inhibit the oxidation of metal sulfide minerals from Young-Dong coal mine and the Il-Gwang gold mine was examined by conducting laboratory scale batch experiments and field tests. Powdered pyrite as a standard sulfide mineral and rock samples from two mine outcrops were mixed with six coating agents (KH 2 PO 4 , MgO and KMnO 4 as chemical agents, and apatite, cement and manganite as mineral agents) and incubated with oxidizing agents (H 2 O 2 or NaClO). For the observed time period (8 days), Young-Dong coal mine samples exhibited the least sulfate (SO 4 2− ) production in the presence of KMnO 4 (16%) or cement (4%) while, for Il-Gwang mine samples, the least SO 4 2− production was observed in presence of KH 2 PO 4 (8%) or cement (2%) compared to control. Field-scale pilot tests at the Il-Gwang site also showed that addition of KH 2 PO 4 decreased SO 4 2− production from 200 to 13 mg L −1 and it also reduced Cu and Mn from 8 and 3 mg L −1 , respectively to −1 (below ICP-OES detection limits). The experimental results suggested that the use of surface coating agents is a promising alternative for sulfide oxidation inhibition at acid mine drainage sites.