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PRESENTED AT T EIGHTH HIGH-ALTZME REVEGETA' t WORKSHOP, <br /> FORT COLLINS, COLORADO, MARCH 3-4, 1988 <br /> - REVEGETATION OF MINED LAND USING PROMAC®•SYSTEMS BACTERICIDES <br /> Marren T. Maierhofer <br /> The BFGoodrich Company <br /> Akron, Ohio 44318 <br /> Microorganisms, by direct:and indirect mechanisms, catalyze the <br /> oxidation of metal sulfides' found in base metal and coal mines, and <br /> play a significant role in the formation of acid mine drainage in ore <br /> stock piles, tailings,- and-waste rock. Elimination of these bacteria <br /> will inhibit acid ; formation• and metals solubilization, thereby <br /> promoting revegetation. -- Acidity'"and resulting solubilization of metals <br /> cause revegetation"•efforts_to_fail frequently. <br /> ProMac Systems of The BFGoodrich Company has developed and refined <br /> controlled release bactericides that inhibit acid generation at the <br /> source. These systems have proven to be an effective and economical <br /> means for reclaiming mined land and improving water quality. <br /> - Chemistry-of-Acid, Formation .. - <br /> = 5 � - ,,Ihec;.stoichiometry of -acid formation has been well described- <br /> (Sing er- and Stumm, 1969 and 1970). Iron is released,into solution and <br /> sulfuric acid is produced in a self-propagating cycle:°which is <br /> catalyzed ',by bacteria. As phi decreases, iron is alter vitively"`tixidized <br /> and reduced,�in the cycle (Figure 1) . - �. <br /> Ferric precipitates;::commonly celled "yellowboy," are formed in a <br /> specific pH range, At pH values less,than 2.5, ferric iron is a strong . <br /> lixiviant and powerful oxidant-- •capable of dissolving a wide variety of <br /> sulfide minerals.' `; Oxidation;=-b -ys,-Terric' iron-'can proceed even i i the <br /> _ %IM6ence of en-,', o��iablesliacteriaxdeep.within a-dum (Hutchins'et <br /> Acid Control Strategies <br /> Numerous acid mine drainage (AMD) abatement methods have been <br /> investigated (Kim, et al, 1982). Kleinmann and Erickson-41986). found <br /> these techniques could be broadly categorized into•"two segments: (1) <br /> techniques that physically limit contact,-b_etwe&r tbe,xreactants,-and (2) <br /> techniques that alter reaction rates.- In the first category, these <br /> methods include compaction, run-off diversion, selective placement of <br /> pyritic materials, physical barriers, etc. ; category number two <br /> includes alkaline or phosphate addition, and bacterial inhibition. <br /> Generally, these techniques have enjoyed some degree of success and a <br /> combination of methods should be employed to insure favorable results; <br /> yet, it makes sense to concentrate efforts into areas where the <br /> greatest degree of control -can be established. <br />