The bioleaching of sulphide minerals with emphasis on copper sulphides — A review

Despite the ubiquity of ferrihydrite in natural sediments and its importance as an industrial sorbent, the nanocrystallinity of this iron oxyhydroxide has hampered accurate structure determination by traditional methods that rely on long-range order. We uncovered the atomic arrangement by real-space modeling of the pair distribution function (PDF) derived from direct Fourier transformation of the total x-ray scattering. The PDF for ferrihydrite synthesized with the use of different routes is consistent with a single phase (hexagonal space group P6(3)mc; a = approximately 5.95 angstroms, c = approximately 9.06 angstroms). In its ideal form, this structure contains 20% tetrahedrally and 80% octahedrally coordinated iron and has a basic structural motif closely related to the Baker-Figgis delta-Keggin cluster. Real-space fitting indicates structural relaxation with decreasing particle size and also suggests that second-order effects such as internal strain, stacking faults, and particle shape contribute to the PDFs.

https://science.sciencemag.org/content/sci/316/5832/1726.full.pdf

The Structure of Ferrihydrite, a Nanocrystalline Material

Mossbauer spectra measured by the Opportunity rover revealed four mineralogical components in Meridiani Planum at Eagle crater: jarosite- and hematite-rich outcrop, hematite-rich soil, olivine-bearing basaltic soil, and a pyroxene-bearing basaltic rock (Bounce rock). Spherules, interpreted to be concretions, are hematite-rich and dispersed throughout the outcrop. Hematitic soils both within and outside Eagle crater are dominated by spherules and their fragments. Olivine-bearing basaltic soil is present throughout the region. Bounce rock is probably an impact erratic. Because jarosite is a hydroxide sulfate mineral, its presence at Meridiani Planum is mineralogical evidence for aqueous processes on Mars, probably under acid-sulfate conditions.

https://science.sciencemag.org/content/sci/306/5702/1740.full.pdf

Jarosite and hematite at Meridiani Planum from Opportunity's Mössbauer spectrometer

The kinetics and electrochemical rate-determining step of aqueous pyrite oxidation

Acid sulfate waters are produced mostly by the oxidation of common sulfide minerals such as pyrite, chalcopyrite, pyrrhotite, and marcasite in rocks, soils, sediments, and industrial wastes. This spontaneous process of mineral weathering plays a fundamental role in the supergene alteration of ore deposits, the formation of acid sulfate soils, and the mobilization and release of acidity and metals to surface and ground waters. The purely natural process of “acid rock drainage” is often intensified by human activities related to mining, mineral processing, construction, soil drainage, and dredging. Geochemical reaction rates are accelerated because physical disturbance gives greater exposure of mineral surfaces to air and water, and to microbes that catalyze the reaction process. Large quantities of reactive sulfides are also concentrated and exposed to air as a result of mining and mineral processing. Acid sulfate waters produce a number of fairly insoluble hydroxysulfate and oxyhydroxide minerals that precipitate during oxidation, hydrolysis, and neutralization. The objective of this chapter is to describe the formation, properties, fate, and environmental implications of the nano- to microphase hydroxy-sulfates of Fe and Al that are precipitated from acid sulfate waters. These minerals are commonly of poor crystallinity and difficult to characterize. Much remains to be learned about their occurrence, formation, and properties.

### Mine drainage

The best known examples of acid sulfate waters are those released from mines where coal and metallic sulfide ores have been exploited (Ash et al. 1951, Barton 1978, Nordstrom 1982a, Rose and Cravotta 1998, Nordstrom and Alpers 1999). There may be as many as 500,000 inactive or abandoned mine sites in the United States alone (Lyon et al. 1993). Although most of these pose no immediate water-quality problem, Kleinmann (1989) estimated that about 19,300 km of streams and more than 72,000 ha of lakes and reservoirs have been …

Iron and Aluminum Hydroxysulfates from Acid Sulfate Waters

The Determination of Free Acid in Zinc Processing Solutions

A Mineralogical Study of the Jarosite Phase Formed During the Autoclave Leaching of Zinc Concentrate

The behaviour of thallium(III) during jarosite precipitation

Nous avons synthetise les composes analogues de la natrojarosite, jarosite, jarosite substituee par le rubidium, dorallcharite, hydronium jarosite, ammoniojarosite et plumbojarosite contenant du V 3 + en utilisantune demarche conventionnelle d'hydrolyse, Quoiqu'une temperature de 100°C est acceptable pour la plupart des syntheses, nous avons eu besoin de chauffer a 140°C pour obtenir une quantite suffisante de l'analogue a V 3 + de la hydronium jarosite. De plus, l'analogue a V 3 + de la plumbojarosite a ete synthetise par reaction d'un excedent de PbSO 4 a 150°C, avec dissolution par la suite du PbSO 4 non reagi a temperature ambiante avec une solution d'acetate d'ammonium. Nos efforts pour synthetiser l'analogue a V 3 + de l'argentojarosite n'ont pas reussi, parce que le vanadium trivalent a reduit l'ion Ag + a l'argent metallique. Les analogues vanadiferes (V 3 + ) des mineraux du groupe de la jarosite se presentent en general en aggregats spheroides faits de cristaux individuels atteignant 3 μm de diametre. Selon les donnees de diffraction X, methode des poudres, tous les precipites adoptent la structure R3m des mineraux de ce groupe; toutefois, aucun signe d'une reflexion a ∼11 A n'a ete decele dans l'analogue vanadifere de la plumbojarosite, ce qui temoigne d'un manque d'ordre impliquant les ions Pb 2 + et les lacunes associees. Nous avons aussi mesure la densite de ces analogues a V 3 + ; les valeurs sont relativement faibles a cause des lacunes dans le site V des structures.

Synthesis and properties of v3+ analogues of jarosite-group minerals

A combination of techniques, including powder X-ray diffraction (XRD), electron microprobe analysis (EPMA), transmission electron microscopy (TEM), and X-ray absorption spectroscopy (XAFS), is used to characterize the common ferric-arsenate-sulfate compounds, which could result from the pressure oxidation of refractory gold ores at elevated temperatures. Three general types of precipitate are identified; namely, arsenate-bearing basic ferric sulfate [FeSO 4 (OH) and designated as BFS], ferric arsenate-sulfate [an extensive solid solution Fe(AsO 4 ) 0.2–0.7 (SO 4 ) 0.7–0.2 (OH) 0.7–0.2 and designated as FAS], and hydrated ferric orthoarsenate (FeAsO 4 ·0.75H 2 O). The crystal structure of FAS is solved by precession electron-diffraction experiments. The structures of BFS and FAS are constructed from octahedral Fe 3+ chains, which are cross-linked by sulfate and arsenate tetrahedra. Extensive substitution of arsenate for sulfate occurs in both types of compounds with charge neutrality being maintained by variations in the (OH) content. The XAFS spectra indicate that the local structures of both BFS and FAS are made of corner-linked single chains of FeO 6 octahedra where the chains are linked by AsO 4 or SO 4 tetrahedra forming alternating layers of FeO 6 octahedra and AsO 4 or SO 4 tetrahedra. Preliminary toxicity characteristics leaching procedure (TCLP) testing of the precipitates indicates that FAS with a molar ratio As/(As+S) ratio of ≤0.5 could be an acceptable material for disposal in a tailings impoundment, whereas more As-rich FAS and BFS may require further treatment. The results for the laboratory-prepared precipitates are compared with those obtained on three residues from the processing of refractory gold ores. The major As-carrier in one of the residues is FAS, whereas As-bearing goethite and hematite are the dominant As-carriers in the other two residues. Thus, the mineralogical characteristics of the residues dictate the appropriate arsenic management and disposal options in the processing of refractory gold ores.

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John E. Dutrizac

Papers

The Determination of Free Acid in Zinc Processing Solutions

A Mineralogical Study of the Jarosite Phase Formed During the Autoclave Leaching of Zinc Concentrate

The behaviour of thallium(III) during jarosite precipitation

Synthesis and properties of v3+ analogues of jarosite-group minerals

Characterization of ferric arsenate-sulfate compounds: Implications for arsenic control in refractory gold processing residues