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. 2.04.6 <br />Iron pyrite is an acid forming material. The reaction of the pyritic sulfur is: <br />2FeS2 + 7'/02 + 71 - - -> 2Fe(OH)3 + 21-12SO4 <br />Or, commonly stated, Iron Pyrite in the presence of oxygen and water will be <br />oxidized to Ferric Hydroxide and Sulfuric Acid. This reaction may be either <br />chemical as described above or microbial. Several species of bacteria gain <br />energy from the oxidation of Iron Pyrite to form the above reaction products. <br />In oxidizing conditions at pH > 4.0, ferric oxide will form. At pH < 4.0 under <br />oxidizing conditions, a mineral called jarosite will form. Jarosite is very <br />insoluble and is not a concern. A common iron mineral, goethite, will form in <br />small amounts across the common pH spectrum under slightly oxidizing <br />conditions. <br />If the acid produced under complete oxidation is not buffered by the <br />surrounding mineral matrix, about 625 pounds of Calcium Carbonate (lime, <br />CaCO3) would be required to neutralize 1,000 tons of material bearing 0.01 % <br />iron pyrite such as in DH -12. <br />Other evidence the area D -Seam coal does not have acid producing <br />characteristics is the old Oliver Mine No. 1 located east of Somerset, CO <br />which mined in the D -Seam in the 1940's and 1950's. This mine is <br />discharging water that is monitored by Oxbow Carbon & Minerals as spring <br />8. This "spring" water consistently has a pH in excess of 7.0 (ref. OCM 1994 <br />Annual Hydrologic Report). <br />Based on the above discussion, it is likely lime is present in ample quantities <br />to neutralize the acid forming component in the coal. Therefore, the acid <br />produced would react with the lime to produce gypsum, water and carbon <br />dioxide. In addition, some soluble sulfates may be formed upon reaction with <br />other base minerals. The reaction is: <br />H + CaCO3 - - -> CaSO + H + CO <br />r <br />PR -12 2.04-21- 07/10 <br />APPRovED <br />1 1116/10 <br />