부산대학교 도서관

Siderite (FeCO3) is commonly found in coal overburden and, when present, can cause interference in the determination of neutralization potential (NP). Under acidic testing conditions, FeCO3reacts to neutralize acid, which contributes to the NP. However, continued weathering of FeCO3(oxidation of Fe2+and hydrolysis of Fe3+) produces a neutral to slightly acidic solution. The effects of hydrogen peroxide (H2O2), potassium permanganate (KMnO4), and O2on the laboratory measurement of NP of siderite samples taken from overburden were examined. All oxidation treatments lowered the NP values of the siderite samples as compared with the standard USEPA method. However, oxidation with H2O2produced variable results depending on the amount of H2O2added. Neutralization potential values obtained after oxidation treatments were highly correlated with Mn concentration. Reaction products (i.e., 2‐line ferrihydrite) of siderite samples with H2O2and KMnO4were not representative of natural siderite weathering. Oxidation with O2produced the lowest NP values for siderite samples. The reaction products produced by oxidation with O2most closely represent those intermediate products formed when siderite is exposed to atmospheric weathering conditions. Oxidation with O2also proved to be the most reproducible method for accurately assessing NP when siderite is present in overburden samples.