Effect of Peroxide on Neutralization‐Potential Values of Siderite and Other Carbonate Minerals

Abstract

To assess quantitatively the effect of peroxide addition to standard static tests of the neutralization potential (NP) of mine wastes, 10 specimens of carbonate minerals, including five of siderite (FeCO3) and two of rhodochrosite (MnCO3), were analyzed by electron microprobe. The compositions of the siderite span a range from 60 to 86 mol % Fe. Tests of NP for the siderite diluted with 80% (w/w) kaolinite gave values of 647 to 737 kg CaCO3 equivalent per Mg for determinations by the standard Sobek method. However, if it is assumed that the ferrous carbonate component of the mineral does not contribute to NP in field situations because oxidation of Fe(II) to Fe(III) and the subsequent hydrolysis of Fe(III) leads to the release of an equivalent amount of acid, then the calculated NP for the samples ranges from 110 to 390 kg CaCO3 equivalent per Mg. Two different methods involving the addition of peroxide to the test solutions were successful in bringing the measured NP values closer to the theoretical ones. By contrast, the tests with rhodochrosite indicated the Mn(II) to be stable. For long-term environmental planning, especially for wastes from metalliferous sulfide-poor deposits in which gradual dissolution of silicate and aluminosilicate minerals may be involved in attenuating the acidity, consideration in the overall NP budget needs to be given to the ferrous iron content of those minerals. The presence of Fe2+-bearing minerals, especially carbonates, in tested mine-waste materials may lead to overestimated Sobek NP values, thus increasing the risk of poor-quality drainage and the need for costly remediation.

Mine Wastes

“…Also, the static tests are based on several assumptions and are, therefore, associated with many problems (Jambor 2000(Jambor , 2003Jambor et al 2003;Miller 1996;Morin and Hutt 1997;Paktunc 1999;Weber et al 2004;White et al 1999): However, the determination of the acid generating potential is not standardized.…”

Physical chemical characterization of historical mining waste and ARD prediction tests

“…MPA is based on total wt% S as determined by LECO analysis [23] multiplied by the stoichiometric conversion factor 30.6, using the following formula:…”

Revue de littérature détaillée sur les tests statiques et les essais cinétiques comme outils de prédiction du drainage minier acide

“…Le premier test statique chimique qui a été développé pour l'industrie minière comme moyen de prédiction du DMA est le test de Sobek (Sobek et al 1978;Miller et al 1991;Lawrence et Wang, 1997;Skousen et al 1997;Jambor et al 2003). Pour la détermination du PN, la méthode de Sobek et al (1978) commence par un test préliminaire appelé test de fizz.…”

“…Pour prendre en considération la génération de l'acidité par le Fe et le Mn (voire l'Al des silicates) lors de la détermination du PN avec le test statique de Sobek, Skousen et al (1997), Jambor et al (2003), Stewart et al (2006) ont proposé l'ajout du peroxyde d'hydrogène (H 2 O 2 ) lors de la titration de la pulpe (en plus du NaOH) pour forcer l'oxydation et l'hydrolyse des éléments chimiques hydrolysables en libérant ainsi l'acidité qui sera considérée lors de la titration. L'ajout du H 2 O 2 permet d'obtenir une estimation plus correcte du PN.…”