An X-ray photoelectron spectroscopy study of the mechanism of oxidative dissolution of chalcopyrite

Parker, Andrew James; Klauber, C.; Kougianos, Adrian; Watling, H.R.; Bronswijk, Wilhelm van

doi:10.1016/s0304-386x(03)00165-8

Cited by 173 publications

(72 citation statements)

References 17 publications

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“…Recent studies examining the microstructure of the solid sulfur phase that forms during bioleaching have focussed mostly on the dissolution of chalcopyrite (Klauber et al 2001, Parker et al 2003, Parker et al 2008, Rodriguez et al 2003. Klauber (2008) recently reviewed the surface chemistry of the oxidation of chalcopyrite and suggested the initial sulfur species formed are S-S dimers or short chain polymers followed by chain extension to form a polymeric allotrope which is finally transformed into the orthorhombic allotrope.…”

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confidence: 99%

The preferential oxidation of orthorhombic sulfur during batch culture

2009

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The formation of sulfur is predicted by the current understanding of the mechanisms involved in mineral sulfide oxidation and observed in studies of the leaching products that accumulate on the surface of the mineral. Sulfur oxidising bacteria can exploit this energy source and can remove a potentially 'rate-limiting' diffusion barrier. In this study on the activity of sulfur oxidising bacteria cultured on mixed solid sulfur allotropes, it was observed that a heterogeneous culture preferentially oxidised the orthorhombic allotrope and no significant growth on the polymeric allotrope could be demonstrated.

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confidence: 99%

The preferential oxidation of orthorhombic sulfur during batch culture

2009

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“…The study by Mwase (2016) also showed that increasing the amount of cyanide concentration in the cyanide-only system had no influence on the amount of Pt leached. (Sasaki et al, 2010;Parker et al, 2003;Klauber et al, 2001;Yuzer et al, 2000;Hackl et al, 1995;Mycroft et al, 1995;Pratt et al, 1994). There are some studies (Arena et al, 2016;Olvera et al, 2015;Yang et al, 2015;Khoshkhoo et al, 2014;Hackl et al, 1995) that have used electrochemistry and XPS to explain specifically the phenomenon of passivation in chalcopyrite leaching, although it is acknowledged that chalcopyrite passivation it is not a similar system to the one explored in this study.…”

Section: Introductionmentioning

confidence: 81%

Characterizing the leaching of sperrylite (PtAs 2 ) in cyanide-based solutions

Mwase

Petersen

2017

Hydrometallurgy

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The mineral sperrylite (PtAs2), unlike other Pt minerals, has shown to be resistant to cyanide leaching, even at elevated temperatures of 50°C. This has prevented further development of a two-stage heap leaching process, of which the second stage is cyanide leaching for a Platreef ore, due to a considerable portion of the Pt being present as sperrylite.Through a comprehensive set of leaching tests, this study has shown that sperrylite leaches slowly in cyanide due to eventual passivation. The addition of ferricyanide to the cyanide solution results in significantly more Pt being leached (up to 16 times) than with cyanide only under identical process conditions. However, over time passivation occurred in this system also, but can be seemingly be overcome by filtering, rinsing and re-suspending the sperrylite. This was further investigated using a reactor system continuously fed with a ferricyanide-cyanide to leach a fixed bed of sperrylite mineral. Again, gradual passivation of the mineral phase was observed, which was fully reversible following a day of feeding with distilled water. XPS analysis of fresh and leached mineral indicated a depletion of As on the mineral surface, which tallied with an observed preferential leaching of As during leaching, at least initially. As a result, it is postulated that a less cyanide-soluble compound of the form PtAs(X) forms, where x is less than 2. The ease with which the leaching process can be restarted after rinsing the mineral indicates that the adsorption of solution species is the key step in forming a passivating layer. This adsorption is potentially favoured by the gradual surface transformation.Finally, an electrochemical study confirmed that the ferricyanide-cyanide system facilitated an electron transfer reaction at the sperrylite surface with the likely oxidation of As and reduction of the ferricyanide. Gradual passivation of the surface was also observed in this system.

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“…This theory was widely accepted, however, it has been demonstrated that neither metaldeficient polysulfides neither polythionates form as stable intermediates over oxidizingly leached chalcopyrite (Biegler and Swift, 1979;Parker et al, 2003). The last theory holds that basic iron sulfate precipitates of the jarosite type are responsible for the diffusion impairing layer that ultimately causes chalcopyrite passivation (Donati et al, 1997;Lundgren and Silver, 1980;Parker et al, 2003;Petersen et al, 2001;Pogliani and Donati, 2000;Stott et al, 2001). However, extensive jarosite precipitation is known to occur abruptly in a later stage of chalcopyrite leaching, forming an initially very porous structure, which cannot significantly hinder diffusion toward or from the mineral surface (Có rdoba et al, 2008a;Espejo et al, 1988;Stott et al, 2003).…”

Section: Introductionmentioning

confidence: 90%

“…A second theory proposes that the diffusion-limiting layer is formed by metal (iron)-deficient sulfides or polysulfides that hinder electron transfer due to a semiconductor effect (Ammou-Chokroum et al, 1977;Parker et al, 1981). This theory was widely accepted, however, it has been demonstrated that neither metaldeficient polysulfides neither polythionates form as stable intermediates over oxidizingly leached chalcopyrite (Biegler and Swift, 1979;Parker et al, 2003). The last theory holds that basic iron sulfate precipitates of the jarosite type are responsible for the diffusion impairing layer that ultimately causes chalcopyrite passivation (Donati et al, 1997;Lundgren and Silver, 1980;Parker et al, 2003;Petersen et al, 2001;Pogliani and Donati, 2000;Stott et al, 2001).…”

Section: Introductionmentioning

confidence: 97%

Non‐homogeneous biofilm modeling applied to bioleaching processes

Olivera-Nappa

Picioreanu

Asenjo

2010

Biotech & Bioengineering

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A two-dimensional non-homogeneous biofilm model is proposed for the first time to study chemical and biochemical reactions at the microorganism scale applied to biological metal leaching from mineral ores. The spatial and temporal relation between these reactions, microorganism growth and the morphological changes of the biofilm caused by solid inorganic precipitate formation were studied using this model. The model considers diffusion limitations due to accumulation of inorganic particles over the mineral substratum, and allows the study of the effect of discrete phases on chemical and microbiological mineral solubilization. The particle-based modeling strategy allowed representation of contact reactions between the microorganisms and the insoluble precipitates, such as those required for sulfur attack and solubilization. Time-dependent simulations of chemical chalcopyrite leaching showed that chalcopyrite passivation occurs only when an impervious solid layer is formed on the mineral surface. This mineral layer hinders the diffusion of one kinetically determinant mineral-attacking chemical species through a nearly irreversible chemical mechanism. Simulations with iron and sulfur oxidizing microorganisms revealed that chemolithoautotrophic biofilms are able to delay passivation onset by formation of corrosion pits and increase of the solid layer porosity through sulfur dissolution. The model results also show that the observed flat morphology of bioleaching biofilms is favored preferentially at low iron concentrations due to preferential growth at the biofilm edge on the surface of sulfur-forming minerals. Flat biofilms can also be advantageous for chalcopyrite bioleaching because they tend to favor sulfur dissolution over iron oxidation. The adopted modeling strategy is of great interest for the numerical representation of heterogeneous biofilm systems including abiotic solid particles.

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An X-ray photoelectron spectroscopy study of the mechanism of oxidative dissolution of chalcopyrite

Cited by 173 publications

References 17 publications

The preferential oxidation of orthorhombic sulfur during batch culture

The preferential oxidation of orthorhombic sulfur during batch culture

Characterizing the leaching of sperrylite (PtAs 2 ) in cyanide-based solutions

Non‐homogeneous biofilm modeling applied to bioleaching processes

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