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4 DISCUSSION C&ULTS CONCLUSIONS <br /> 4,1 Leachability Four water treannent sludge samples from the Mayflower impoundment at the Climax Minc were <br /> subjected to SBE analysis to evaluate their geochemical stability during leaching. Chemical and <br /> Contrary to other siudies of water treatment sludge stability(i.e.Zinck 1997;Zinck el el.1997), mineralogical analysis(Ford et al.1997,this volume)indicate that samples can be subdivided into <br /> this investigation did not employ the use of the Toxic Characteristic Leaching Procedure(TCLP; those dominated by sludge and those with a Significant tailings component derived from the <br /> EPA M 1311).or other similar protocols(i.e:the Ontario Leachate Extraction Procedure)that call impoundment when sludge is precipitated. <br /> for the use of acetic acid lixiviams to simulate conditions within municipal landfills. The primary Evaluation of leachability using the SBE test indicates that the sludge-rich samples have a <br /> justification for using tests other than these is that the water treatment sludges at Climax arc considerable ability to buffer the pH ofm y Ieachate,and thus tocontrol metal concentrations. The <br /> disposed of within a tailings impoundment,and thus will not came into contact with significant sludge attenuates concentrations of Fe and Mn that were present in the lixiviant. Negligible <br /> quantities of organic acid. contributions of Al and Cs are imparted to the Ieachate by the sludge at pH 7 and 9. <br /> In this evaluation of waste water treatment sludge stability, SBE tests employed fluids <br /> reasonably expected to come into contact with sludge to evaluate whether metal-bearing <br /> precipitates would dissolve at PH 7 and 9 under conditions of varying fluid-sludge ratios. 6 ACKNOWLEDGMENTS <br /> Analytical results demonstrate die differing geochemical behavior of samples dominated by sludge This paper P <br /> and those with a significant tailings component. P p could not have been completed without technical assistance and advice from D. <br /> For sludge-rich samples,the pH of the lixiviant does not appear to significantly affect the final Brosnahan, R.Corbett,T.Van Wyngarden and R.Paulsen, This paper is published with the <br /> PH of the Ieachate,indicating that buffering of the fluids is occurring by the Solid phase. After I Pa^nlssi(m of Cyprus Amax Minerals Company,which is gratefully acknowledged, Critical <br /> initial excursions,the pH of the final Ieachate stabilizes at 9.5-9.0 for both pH 7 and 9 lixiviants, reviews by J.W.Danni,L.A.Darlin& W.D.Doepken,C.G.Janes and F.J.Kane improved the <br /> The equilibrium pH for the dissolution of calcite under atmospheric conditions is 8.4(Garrels& I paper. P • <br /> Christ 1965 p.83),suggesting that calcite dissolution may in pars be responsible for buffering of <br /> Ieachate PH. Buffering may also be provided by unreacted lime and dissolution of ettringite, REFERENCES <br /> although the buffering contribution from these phases is unknown. <br /> The PH of Ieachate from tailings-rich samples is mom variable, forming an envelope Fad,R.C.,Clapper,r <br /> surrounding the values from sludge-rich samples. The Ieachate from the 5-dam sample approaches J.L.&Romi&B.R.1997.Stability of water treatment sludge,Climax Mine, <br /> that of the lixiviant at both PH 7 and 9, indicating that buffering is largely provided by the Colorado. L Physical and mineralogical Properties In Tailings and Mine Waste '98, this <br /> Iixiviant. The PH behavior of the 3-dam Ieachate is unexpected, given the mineralogical volume, <br /> similarities between it and the 5-dam sample. Them is clearly an unidentified mineral phase in the Gamis,R.M.&ChriS4 C.L.i%5.Solraion;minemlt and egailrbria.San Francisco:Cooper and <br /> 3-dam sample which is capable of buffering to elevated PH. Company. P <br /> The sludge-rich samples,despite their elevated metal contents compared to the tailings-rich White, W.H., Bookstrom, A.A., Kamilli, R.J., Ganster, M.W., Smith, R.P., Rants, D.E. & <br /> samples,consistently demonstrate that Fe and Mn present in the lixiviant am attenuated by the Steininger,R.C. 1981.Character and origin of Climax-type molybdenum deposits. In B.J. <br /> sludge during leaching at PH 7 and 9,as messured by the ratio GG. Aluminum is attenuated by Skinner fed),Economic Geology Sevemh--fifth Ann iversmy Volume:270-316. <br /> the 6-riser sample,but C/C,for the delta sample is slightly mom than one,indicating that some Al Voynick.S.M.19%.Clise¢r:the hi y oJColamda i C1artas'Malybdenrun Mme.Missoula,MT: <br /> is contributed by the sample to the Ieachate. Data indicate that Ca is leached from the sludge, Mountain Press Publishing Company. <br /> although again the ratio Gip remains at or next one over the range of fluid-sludge ratios. Despite Zinck, J.M. 1997. Acid mine drainage treatment sludges in the Canadian mineral industry: <br /> the slight contribution of Al and Ca to the Ieachate,the absolute concentrations of these elements Physical, chemical, mineralogical and leaching characteristics. Proceedings of the Fourth <br /> lnttmarional Co stance on Acid Rock Drainage. PaRcOwer•B,C.: 1693-1708, <br /> era low,and would not contribute to any degradation of water quality. ^f <br /> Leaching of the two tailings-rich samples shows that Al and Fe are attenuated. The behavior Zimk, J.M., Wilson, L.J-, Chen, T.T., Griffith, W.. Mikhail, S. & Turcotte, A.M. 1997. <br /> of Mn and Ca differs between the samples,with the 3-dam sample attenuating Mn and Ca to low C 4Characterization 61 + and stability of acid mine drainage treatment sludges.MEND interim Report <br /> concentrations. The 5-dam sample on the other hand shows progressively less ability to attenuate P. appendices. • <br /> Mn at bath pH 7 and 9 n fluid-sludge ratios increase,although eachate Mn concentrations do not <br /> exceed the initial lixivism concentration. This pattern,particularly at PH 7,is father confirmation <br /> of the inability of the 5-dam sample to buffer PH,as precipitation of Mn-hydmxide minerals <br /> generally occurs at pH greater than ten. The behavior of Ca in the 5-dam Ieachate mimics that of <br /> the sludge-rich samples in that Ca is contributed to the leschate by the sample,although 0C. <br /> shows only slight excursions from unity. <br /> The stability relations of ettringite suggest that it begins to dissolve in the range of PH 10,with <br /> dissolution complete by pH 2. This,combined with data from this study and knowledge of metal <br /> hydroxide stability,indicate that if pH in Mayflower pond were to fall substantially below neutral, <br /> metal•bmaring species could dissolve. Such dissolution could be incongruent, leading to <br /> precipitation of other minerals. <br /> 666 667 <br />