Mine Drainage and Surface Mine Reclamation. Volume I: Mine Water and Mine Waste. Vol. I. Pittsburgh, PA: U.S. Bureau of Mines, 1988 Apr; :21-28
The relationships between geochemical measurements and the chemistry of leachates collected in weathering tests were explored for 139 overburden samples. All samples were analyzed for total sulfur (ST) and neutralization potential (NP) and 95 had sulfur fractionated into pyritic, sulfate, and organic forms. All samples were weathered for 6-8 weeks in a laboratory, and leachates were collected and analyzed weekly for acidity, alkalinity, and sulfate. All data were normalized with logarithmic transformations. Cumulative sulfate produced in the weathering tests was strongly correlated with total sulfur (r=+.83). The relationship with pyritic sulfur was much weaker. NP had a negative influence on sulfate production, but the correlation was weak (r=-.27), especially for samples with NP less than 30 tons per 1000 tons. Multiple regression analyses relating weekly sulfate production to neutralization potential and sulfur forms identified sulfate sulfur as the most important independent variable. Pyritic sulfur was not a significant factor in any week's analysis. When only samples that had produced more sulfate than could be accounted for by sulfate sulfur measurements were considered, pyritic sulfur became a significant component in the sixth week, and the dominant component in the eight week. Cumulative acidity/alkalinity, expressed on a single scale, was significantly correlated with total sulfur (r=+.37), NP (r=-.43) and the difference of neutralization and acid potential Net NP (r=.61). Estimates were made of the cumulative neutralization generated by each weathered sample by comparing sulfate and acidity/alkalinity production. For most samples, less than 10% of the NP had been consumed in the 6-8 week tests. All samples with more than 25% consumption produced acidic leachates.