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• • Step four: All combined to create a dilute sulfuric acid run-off. <br />FeS2 + 15/4 OZ + 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 />Oaerationby 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"a 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 />M2+ + 2(0H)" = 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(Off)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 dryfeeder <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 />According to the EPA's own work in this vicinity, this method achieves the following. <br />REPROCESSING: REPROCESSING WILL RESULT IN NEW TAILINGS THAT ARE NOT RCRA <br />WASTES. HOWEVER,POTENTIAL LEACHATES FROM THE WASTE WILL EXCEED AWQC**. <br />REPROCESSING REDUCES MOBILITY, TOXICITY AND VOLUME OF THE CONTAMINANTS. <br />THIS ALTERNATIVE IS THE ONLY OPTION THAT REDUCES VOLUME. REPROCESSING <br />REDUCES EXISTING RISK TO HUMAN HEALTH AND THE ENVIRONMENT. THIS OPTION IS <br />THE MOST EXPENSIVE OF THE SIX ALTERNATIVES EVALUATED EVEN CONSIDERING THE <br />VALUE OF THE MINERALS EXTRACTED. OVERALL, REPROCESSING IS A PERMANENT <br />SOLUTION THAT REDUCES EXPOSURE TO HUMAN HEALTH AND THE ENVIRONMENT. <br />**[Note by Venture Resources: Ambient Water Quality Criteria will be <br />potentially exceeded, meaning having a better state.] <br />EPA Record of Decision, ROD R08-88/019,1988 <br />6.4.20(15)(a-b) <br />• Reference Exhibit C, 6.3.3(l)(e) for a description of the significant components of this operation, also locatable in <br />Exhibit E. <br />24