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OCT-29-96 TUE 12136 PM <br />>~ <br />SHEPHERD MILLER FRX N0. 970 223 7171 <br />• <br />D. w. Bbvcs and 1. L Jfmhor <br />Table t. Daeiptien td 1M wl(de altenrion ineki a uad <br />in tM tttitaralopd xndy <br />Nutttmieal <br />sole Dep+ee of iltendm of tttldda <br />10 Pyrrhotee sad pyrite obtiterstedd tidy <br />tram d malde, typitauy ebalntpyrite, arc <br />P~m• <br />9 Similar m 10. Itat rith k. scattered <br />temuai pains of pyAa. <br />-a-7 Frp appearaiaz of trace arrronrns of <br />pythotite far sole ~: a teak 7 the <br />venips err tatonpy altered pyrrhodta <br />itteease ie alttutdaoce Ot Otgtrt d <br />~~ <br />~2 At stale 6 the pyrrltaalte palm have brttad <br />iltmtiao Ants, but the Dotes of nutnerOtu <br />griln ace pereved; gradaebn to ask 3 <br />e marked h ds appearme td narrorer <br />alteration ties and a prcdominanee d <br />nnahued grants. <br />I-0 Only a An palm of pynhotire ate neatly <br />aheted alms Atas and ftaLttua: >95 : d <br />pains tow chary. Iruh tettpns <br />Waite Amulet taIDttp ate the depletion of mlAdc <br />minerals in the Dearsub-surface zone of the tailings. <br />and the abrupt dtdiae is the gas-phase 03 crntcen- <br />¢7tioats at the mne of attire oridatbn. Based on <br />tttieroscopic stadia. the degree o[ the alteration <br />intcmiry of the Waite Amulet ntliap trot dassifled <br />on a telapve snlc d 0 to to n desetbed in Table 1. <br />Profile o(gas-phut Ot• C6= mtrrnttatioat and <br />calfide dieratiat vs depth for four of the eight thill- <br />sites studied are pi6ented is Flg. 3. Tht hltGmty of <br />wifidc oxidation in these profiles shots a da,:rcate <br />that eortespottds Basely to the abrupt dediae in the <br />gss.phttx Ot cottcetnration. - <br />Miaeralogio! analyses of Ne coca show apro- <br />gressive dottrvward decrease in altentit7n inttttsiry_ <br />At die southern tad of the impoundment. the pro• <br />gressions iatertvped by a welldeflud acne a( <br />palt:owr(aw oxidation. For the Impoundment as a <br />whole the oxidation prolila an be generalind 'into <br />wAx oaa-. co2 tzl wAn o,. co, txl <br />0.0 t0.0 3e.o 0.0 q.0 30.0 <br />ea `4 o.e <br />of <br />~aZ ` <br />a0 m i4i <br />S <br />F <br />6 <br />B' a0 a.e <br />30 as <br />o.o ao r.e os a.e n.o <br />SJ~I. SLI. <br />three moo: a wNdedepleud mne. dtarxterized <br />by strongly taxit8aed ut1'np. as inrermedure mne <br />rbaraaestzed by tnaderatc m .ale aherarba and <br />mat+osite ttplaeeatent of pyrcbotite. attd as tut. <br />aherad mne .Mm the tailing shw negligible oxi- <br />dation. <br />N the wlfldedtgleted mne aNy trnce remttanta of <br />pyrite and chalmpytite can be fouttd. [he bulk d the <br />sulfide having Deea asidixed and rcplaeed, The <br />pritldpal altt:ratioo toinerals an gae[hite, retd ether <br />Fevxyhydro>ddes slut include IepNoaotloe and (er- <br />rihytlrire. The observed order of stilfide tnitteral rc- <br />moval follors the order gencta0y observed for <br />sulAde-mineral stLSCepa~ility to taiaobial oxidation <br />(Table 13.7 in Btttscx rt d., 19Rt). Pytrhtstac. the <br />most stLtmptble o(the eammon sulfides to micrtrbial <br />oxidation. Is ryplWty completely rtplatxtl thrmeJ- <br />ou[ the wlhdc.fepkted zone. In the intmntrllate <br />scant ptmrltotue has been strongly altered t+tn scot <br />tabliterated. Initial alteration of pyrrhotite is ~widcnt <br />from partial rcplaeeatrnt by matrasite and wlfates <br />along pain boundaAes (Fig t, S) and prngrwivc <br />nylateaient o(thae phases br goethite and k-piduc- <br />rode to tottn ferric oxyhydroxide cites around pres- <br />haite grains. Similar tt>adation durxteristiu trove <br />been tto[ed is heap•Iexb piles anti in naturally uai- <br />dizing waste-rock dumps. <br />Modelling ru(jrdeoridmian rrxrions <br />Recognition of sulllde oxidation eharxterctties hzs <br />led w the development of a soles of mathematical <br />n3odeU Deed mrxzptttaQy oa rricions acLVrring at <br />the surface o(a shrinking core o! sulfide mineral <br />within an oxide reaatoa rim. [o these models, trhich <br />have been sttmmariaed by DAtns and RrmttE (1986), <br />the rate of w(fde axidadoa is contrdkd by di8iedon <br />a( the o>;dant (O,(g) or F2") tlawgh the oxide <br />reaction-rlm to Ne std6de surface. Initially. these <br />tttodeb overt developed to describe iW6t1e aaidatioo <br />m nnp-leach ore protxitiDg. During the heapdeaeh <br />process the oxidant 6 coatintsoudy replenished <br />WAR O,. CO, (%! wAa3 O . CO, (%1 <br />e.e r.o ae.s a.e ~ a t%.e <br /> <br />0.0 0.0 ~~ <br /> t <br /> <br />~ t <br />a7 <br />t0 f.•L LO <br /> a. A.L <br />sa as <br />a.a ere <br /> 0.0 a.a q.e e.a la r.0 <br /> SJJ. SAl <br />Fro. 3. Contztttratiom of osygtn (equates) and tartan dioxide (eirda), and ad6de ilietvdoe itdes <br />(S.A.I.~ro nnrtm) .etsm depth u tltex wAI, wA 11, wA17 and WAZt. The position of the .stet <br />uhk on the sawpGttg date b indtc~ted b7 die inrened taangle, .ucr ODk WA17 and WA"1 is >3 m <br />deep. <br />P. 21 <br />diraug <br />teiltitie <br />ata{!ly <br />Paticl. <br />tag a,: <br />