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the -rates o4 railings autidatioa ~th two iadapattdetrt methods. Ones ~ based on We anal <br />tikaoived moues of iron std sulphate that oe:curred is the inns above the avatar able far which the ~ <br />tesideace time wan estimated from mown ioflltruioa rue (mesa balance taathod). Thn oxidation rue wan €~ <br />then ealtatlated as the mau of aciditloa ptttduet per aoit stn divided by the then fat oxidation is the aix- <br />yearold ts(Ihaga. The other estimate of oxidatiaa talc was roads from a calculation of oxygen diffitsba <br />wing Fidt's first law (oxygen gradient method). Oxygen-;era ooacxnotitioa-~tadieats were ttteasated in <br />the shallow sttbetufacs of the tatlhtglt. The degtroe of wage sitttradoa of the atlhtp stavaa the same zone <br />were also meaautrod oo estimate the a~tfeetlve diffitaion ooeffiaaat tbt oxygen gas in the tailings. The <br />ealaiated 81u was given fa the mass of oxygtm eateriog a wait area of the mlings staface per mil time <br />eras compared m the mau Buz calculated tttmt the meat of oxidation produaa produced since deposition <br />of the tailings. <br />>x was tewgttised thtt bath of tlteae atetboda have fohetaat tmcettmntia that tea atEscc the <br />picutared rite. 7'he mass balance tt-ahod 6 mbjea m atota when praipindon sad diuolatlon ractiow <br />occur for iron and sulphate. 1< was also tecagnised that one of watt saduadoa m estimate the diffusion <br />eoe!lldeatu will tRad m over-atimue oxygen 8ux values verdaily d~roagh the taitiapt. Howes, la sphe <br />of the uncataiatiea, ells trvo taethodt ptrnided trsulis that txmtpata4 well oa a relative besfa from place . <br />ro p[ace. The rates revealed waicipated ttoads with highs vahta to arw thst was well drsieed sad `; <br />lows values In arat with high degrees of water aantritioa Almost threeordaa~ot-magnitude ditYaeoce ;~ <br />in rite were observed between drained etas and thane with s wa low-sulphur sfimet layer near rho ;a. <br />ground surface. F16erling a ai. (~ demonstrated that the oxygen gradient method also provided spatially ;~ . <br />comisteat trends for rates in an era ;a the vicitutq of goaded tailings with m increase is Hues by mote ,'~ <br />than a factor of 100 from the edge of the pond m a distance o[ a sew barrelled taetra from the pond. <br />Thane methods sppea m provide useful results in cotttpariog oxidation rates across a site. Utdortuaatdy, <br />there measutxmeat mahoda also require detailed saatpllog std iaborttory aaalysia. The oxygen gradient ~ ` <br />method is by f!r simple than the arses balance atethod but umpliag u any site may requiro.signi8caa <br />effort m obtain the necessary daft. <br />'s <br />An innovative sad efficient method has been developed to estitaau oxidation rates ut tailings <br />measuring the rxe of oxygen consumption that oecura it ells tatlittga tattface. This method trta 8 <br />daaonstrated in the laboratory when the oxygen cottautttpdon rite eotrdetnd well with rata eathm~ <br />from mass balance for sulphite produced sad the oxygen gtadleot method t'i). The tesaltn of I <br />laboramry stadia snggeated that steady-state oxidation rata ware aaainad within two daga a8er flttshi <br />the tailings mlamn with water sad that the coawarptioa meaaureatetm required onlq one haft. <br />motiltoting that could be conducted da~q without attaing she emblem rata of oxidation. TLe oxyg <br />wttsutaptioa tnabod wan then aQaptad for ftdd measureareata and orated for a variety of condhions: <br />the 5dd meaatuemeau are presented bee with a deaczlption of the meastaemesK techniques. <br />theory relating the masuremeata m ram of oxidation noel the malts of some applic~on of the oxy, <br />comumption method it fteld tat aim. The implications of the resold its discussed in the ootttat of <br />conceptual molds of rate wtttrols oa oxidation rata in a field netting std the use of fens-grained not <br />m inhibit oxidation and aril geaaition. <br />jZi~of Oxva~ Conauete~on Mefaat~ertta <br />The oxidation of suiphtde miaerali itrvolva the wototaption of oxygen wNb ptodtu <br />various species of iron sad sulphur that may elitist u a result of ettviroataeoul woditloro, lHa <br />field and laboratory evideaa suggeua that the stoat common products of oxidation in tm7ings ~ <br />iron (Fe'') sad sulphite (SO.}). if we wnsWer pyrrhotite sa the Primary sulphide wasto, ells a <br />reaction pa be written era: - <br />1000 <br />