COAL PYRITE PASSIVATION DUE TO HUMIC ACIDS AND LIGNIN TREATMENT

A significant decrease in pyrite dissolution rate can be achieved by s ubjecting it to a humic acids treatment. In this study, the following two sources of pyrite were used: (i) an acid refuse (coal slurry) samp le, and (ii) a coal pyrite sample. In addition to pyrite dissolution r ate measurements, column studies also were carried out. The leachate i ron, sulfur, chromium, vanadium and cadmium metal contents were determ ined. Pyrite passivation was also studied using some model compounds o f humic acids. The data obtained suggest that catechol and 4-aminophen ol addition to pyrite can result in a significant suppression of pyrit e dissolution under nitrogen and air atmospheres whereas oxalic acid a ddition enhances pyrite dissolution. In a related research work, it is shown that lignin addition also results in a decrease in pyrite disso lution rate.