The self-heating of sulfides: Galvanic effects

Payant, R.A.; Rosenblum, Frank; Nesset, Jan E.; Finch, J.A.

doi:10.1016/j.mineng.2011.10.019

Cited by 33 publications

(16 citation statements)

References 10 publications

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“…The dissolution of pyrite therefore increases the Fe concentration, resulting in a decreased Cu to Fe ratio as shown in Figure 1b. However, stoichiometric Cu to Fe dissolution of chalcopyrite at 650 mV is expected (Figure 1b), regardless of the presence of pyrite, as this Eh is less than the rest potential of pyrite but greater than that of chalcopyrite [38] and little dissolution of pyrite occurs. These findings are of significance in providing better understanding of the factors affecting dissolution rate of mixed chalcopyrite and pyrite systems in AMD systems within the most often observed Eh range of 500-800 mV (SHE) [39][40][41].…”

Section: Discussionmentioning

confidence: 91%

Chalcopyrite Dissolution at 650 mV and 750 mV in the Presence of Pyrite

Qian

et al. 2015

Metals

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Abstract:The dissolution of chalcopyrite in association with pyrite in mine waste results in the severe environmental issue of acid and metalliferous drainage (AMD). To better understand chalcopyrite dissolution, and the impact of chalcopyrite's galvanic interaction with pyrite, chalcopyrite dissolution has been examined at 75 °C, pH 1.0, in the presence of quartz (as an inert mineral) and pyrite. The presence of pyrite increased the chalcopyrite dissolution rate by more than five times at Eh of 650 mV (SHE) (Cu recovery 2.5 cf. 12% over 132 days) due to galvanic interaction between chalcopyrite and pyrite. Dissolution of Cu and Fe was stoichiometric and no pyrite dissolved. Although the chalcopyrite dissolution rate at 750 mV (SHE) was approximately four-fold greater (Cu recovery of 45% within 132 days) as compared to at 650 mV in the presence of pyrite, the galvanic interaction between chalcopyrite and pyrite was negligible. Approximately all of the sulfur from the leached chalcopyrite was converted to S 0 at 750 mV, regardless of the presence of pyrite.At this Eh approximately 60% of the sulfur associated with pyrite dissolution was oxidised to S 0 and the remaining 40% was released in soluble forms, e.g., SO42− . OPEN ACCESSMetals 2015, 5 1567

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Section: Discussionmentioning

confidence: 91%

Chalcopyrite Dissolution at 650 mV and 750 mV in the Presence of Pyrite

Qian

et al. 2015

Metals

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“…As the rest potential of galena (0.40 V SHE) is less than that of either pyrite (0.66 V SHE) or sphalerite (0.46 V SHE) (Majima, 1969), galena when in galvanic contact with these minerals will tend to oxidise preferentially (Peng et al, 2003;Chandra and Gerson, 2009;Payant et al, 2012;Rao and Finch, 1988;Kwong et al, 2003). Oxidation of the anodic mineral is frequently accompanied by the dissolution and re-adsorption of its metal ion(s) onto the original mineral and the surface of other minerals (Cullinan et al, 1999).…”

Section: Discussionmentioning

confidence: 99%

The impact of iron sulfide on lead recovery at the giant Navan Zn–Pb orebody, Ireland

Barker

Gerson

Menuge

2014

International Journal of Mineral Processing

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It has been proposed that blending of Navan Conglomerate Group Ore (CGO) with Pale Beds Ore (PBO), the latter which floats well in isolation, results in suboptimal Pb recovery with increased abundance of pyrite reporting to the concentrate and increased abundance of galena reporting to the tails. and is likely present due to entrainment. The presence of framboidal pyrite in CGO is of particular significance as its large surface area increases the rate of galvanic interaction with other metal sulfide minerals. We propose that increased abundance of refractory framboidal pyrite in CGO is the critical factor affecting the performance of the Navan Pb flotation circuit rather than purely high pyrite abundance.3

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“…Exothermic oxidation of iron sulphides is an associated common cause for self-heating and has been observed in iron sulphide bearing coal and numerous mines and milling operations (Li and Parr 1926;Rosenblum and Spira 1995;Ninteman 1978;Payant et al 2012). Mariner et al (2008) reported selfignition of pyrite in organic shales caused by a landslide, leading to air penetration to pyrite nodules.…”

Section: Mechanisms For Self-combustionmentioning

confidence: 99%

“…Heat can spontaneously be generated by a few natural exothermic reactions including exothermic oxidation of fine-grained iron sulphide minerals (Rosenblum and Spira 1995;Payant et al 2012), which is the most assumed cause of ignition and it is a common phenomenon in coal combustion.…”

Section: Introductionmentioning

confidence: 99%

Spontaneous self-combustion of organic-rich lateglacial lake sediments after freeze-drying

et al. 2016

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We report and investigate for the first time spontaneous self-combustion of freeze-dried lacustrine sediments immediately after ventilation of the vacuum freeze dryer chamber. The smouldering and flameless combustion lasted for approximately 10-20 min and reached temperatures of 357°C. Selfcombustion mainly occurred in aluminium boxes containing sediment bars taken for thin section preparation. About 40 % of these samples were affected, most of them originated from the basal approximately 3-m-thick finely laminated lateglacial sediment interval. The combustion process caused disintegration of siderite to iron oxides (hematite and magnetite) and burning of organic matter to pyrogenic carbon leading to a lowering of total inorganic and organic carbon contents to 1 %. The total sulphur content of one combusted bulk sample did not change, but the alteration of sulphur contents in different sediment components suggests a redistribution of sulphur within the sediment. We assume that the self-combustion process was initiated by exothermic oxidation reactions, which were favoured by a combination of factors including the presence of abundant fine-grained iron sulphides in the organic-rich sediments. Self-combustion could be prevented by ventilating the vacuum chamber after freeze-drying with N 2 .

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The self-heating of sulfides: Galvanic effects

Cited by 33 publications

References 10 publications

Chalcopyrite Dissolution at 650 mV and 750 mV in the Presence of Pyrite

Chalcopyrite Dissolution at 650 mV and 750 mV in the Presence of Pyrite

The impact of iron sulfide on lead recovery at the giant Navan Zn–Pb orebody, Ireland

Spontaneous self-combustion of organic-rich lateglacial lake sediments after freeze-drying

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