Impurities and heterogeneity in pyrite: Influences on electrical properties and oxidation products

The effect of As, Co, and Ni impurities on pyrite oxidation kinetics: Batch and flow-through reactor experiments with synthetic pyrite

“…The partially oxidized sulfur ions are thought to react with H 2 O (Reedy et al, 1991) and are eventually released as sulfate into solution along with ferrous iron. We observe Asdoped synthetic pyrite to be most often p-type, i.e., has holes for charge carriers (Lehner et al, 2006) as is natural pyrite with As as the main impurity (Shuey, 1975;Savage et al, 2008).…”

A critical review of acid rock drainage prediction methods and practices

“…Processes of pyrite oxidation are generally controlled by several other factors including pH (Evangelou and Zhang, 1995;Dold, 2010), oxidant type (O 2 or Fe 3+ ; Moses and Herman, 1991;Moses et al, 1987;Hustwit et al, 1992), oxidant concentration (Lottermoser, 2010), morphology (Weber et al, 2004;Lottermoser, 2010), and trace element contents (Kwong, 1993(Kwong, , 1995Jambor, 1994;Plumlee, 1999;Blanchard et al, 2007). Oxidation is further complicated by the electrochemical nature of pyrite which is a semiconductor, thus the exact chemical composition of the sample will dictate the specific oxidation pathway (Evangelou and Zhang, 1995;Rimstidt and Vaughan, 2003;Egiebor and Oni, 2007;Savage et al, 2008;Chandra and Gerson, 2010).…”

Microelectronic junctions in arsenian pyrite due to impurity and mixed sulfide heterogeneity

“…Importantly from a geochemical perspective this OCV may still provide a driving force for diagenetic chemical change by shifting Eh for a particular rock-fluid reaction. For example, both observation and calculations based on density functional theory (DFT) suggests As, Ni, and Co substitution and their heterogeneity results in higher oxidation rates during pyrite flotation (Abraitis et al 2004;Savage et al 2008;Li et al 2011). These effects are not to be confused with the fact that a low concentration of vanishingly soluble impurity atoms also reduces mineral stability providing a thermodynamic reason for higher reactivity.…”

“…Evidence pointing to junctions related to As-Ni variation was obtained although a direct correlation was not possible due to the sheer complexity in both the elemental zoning and LBIC maps. baCkground Impurity heterogeneity, structural imperfections, and small changes in stoichiometry leading to variation in electrical properties are typically measured via their influence on resistivity (Abraitis et al 2004;Savage et al 2008;Lehner et al 2006). Illustrating the scale of spread in resistivity, an early compilation by Pridmore and Shuey (1976) on natural pyrite found n-type samples to span four orders of magnitude.…”