Laserfiche WebLink
• Step two: Iron oxidizes to ferric iron. <br />FeS2 + 7/2 02 + H2O --> 2SO4 2 + Fe+2 + 2H} <br />• Step three: Precipitation occurs with ferric iron to ferric hydroxide. <br />Fe+3 + 3H2O --> Fe(OH)3 + 3H+ <br />• Step four: All combined to create a dilute sulfuric acid run-off. <br />FeS2 + 15/4 O2 + 7/2 H2O --> 2H2SO4 + Fe(OH)3 4 <br />For a very conclusive analysis of this phenomenon please reference A Water Handbook for Metal Mining <br />Operations, by Thomas R. Wildeman (attached in the appendix of Exhibit Q. This work was done considering <br />specific examples in this vicinity. <br />Using lime in the mill process stream to regulate the pH to a more alkaline level is a good way to manage the <br />dissolved metals. According to Physicochemical Treatment Processes, Volume 3, 2°d edition, 2005, by Lawrence K. <br />Wang, Yung-Tse Hung, and Nazih K. Shammas: <br />"Dissolved heavy metal ions can be chemically precipitated as hydroxide for removal by physical <br />means such as sedimentation or filtration. The process uses an alkaline agent to raise the pH of <br />the water that causes the solubility of metal ions to decrease and thus precipitate out of the <br />solvent. <br />A simple form of the hydroxide precipitation reaction may be written as <br />AP + 2(OH)- = M(OH)2 (1) <br />The product formed is an insoluble metal hydroxide. <br />Reagents commonly used to effect the hydroxide precipitation include alkaline compounds such as <br />lime or caustic soda (sodium hydroxide). Lime in the form of quicklime or un-slaked lime, CaO, <br />and hydrated lime, Ca(OH)2, can be used. Lime is generally made into wet suspensions or <br />slurries before introduction into the treatment system. The precise steps involved in converting <br />lime from the dry to wet stage will vary according to the size of the operation and the type and <br />form of lime used. In the smallest plants, bagged hydrated lime is often charged manually into a <br />batch-mixing tank with the resulting "milk-of-lime" (or slurry) being fed by means of a solution <br />feeder to the treatment process. Where bulk hydrated lime is used, some type of dry feeder <br />charges the lime continuously to either a batch or continuous mixer. " <br />The precipitated metal hydroxides, sulfide minerals, and free metals are collected in the concentrate products <br />produced by the mill. Reference Exhibit C, 6.3.3(1)(m) for a description of the mineral processing operation. <br />25