Dissolution of hematite in acidic oxalate solutions: the effect of ferrous ions addition

Panias, Dimitrios; Taxiarchou, Maria; Douni, I.; Paspaliaris, Ioannis; Kontopoulos, A.

doi:10.1016/0304-386x(96)00004-7

Cited by 28 publications

(25 citation statements)

References 12 publications

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“…(2) the activities of aqueous species acting as inhibiting or catalyzing agents, most prominently Fe 2+ (Panias et al 1996); (3) the reactive surface area of the hematite (Echigo et al 2012); and (4) the undersaturation level of hematite (Hersman et al 1995). The linear behavior of the Avrami plots (Fig.…”

Section: Reaction Mechanism For the Replacement Of Hematite By Chalcomentioning

confidence: 96%

“…These calculations assume that redox is controlled by S and that the equilibrium Fe(III) solubility (<1 ppt) is controlled by Fe(OH) 3 (aq) and Fe(OH) 4 -complexes. Reductive dissolution of hematite is an efficient process even at room temperature (Panias et al 1996). Therefore it is likely that some Fe in solution in our experiment is reduced to Fe(II), resulting in the oxidation of some of the S. The reductive dissolution of hematite in our experiments can be written:…”

Section: Reaction Mechanism For the Replacement Of Hematite By Chalcomentioning

confidence: 97%

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Experimental study of the formation of chalcopyrite and bornite via the sulfidation of hematite: Mineral replacements with a large volume increase

Jing¹,

Brugger²,

Chen³

et al. 2014

American Mineralogist

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Chalcopyrite (CuFeS 2 ) and bornite (Cu 5 FeS 4 ) are the most abundant Cu-bearing minerals in hydrothermal Cu deposits, forming under a wide range of conditions from moderate-temperature sedimentary exhalative deposits to high-temperature porphyry Cu and skarn deposits. We report the hydrothermal synthesis of both chalcopyrite and bornite at 200-300 °C under hydrothermal conditions. Both minerals formed via the sulfidation of hematite in solutions containing Cu(I) (as a chloride complex) and hydrosulfide, at pH near the pK a of H 2 S(aq) over the whole temperature range. Polycrystalline chalcopyrite formed first, followed by bornite.Assuming that Fe behaves conservatively, the transformation of hematite to chalcopyrite involves a large increase in volume (~290%). The reaction proceeds both via direct replacement of the existing hematite and via overgrowth around the grain. Chemical exchanges between bulk solution and hematite are enabled by a network of micrometer-size pores. However, in some cases the chalcopyrite overgrowth develops large grain sizes with few apparent pores and in these cases fluid transport may have been via a network of fractures. Similarly to the replacement of hematite by chalcopyrite, bornite forms via the replacement of chalcopyrite. The reaction has a large positive volume (~230%), and proceeds both via chalcopyrite replacement and via overgrowth.This study shows that replacement reactions can proceed via coupled dissolution-reprecipitation even where there is a large volume increase between parent and product mineral. This study also provides further evidence about the controls of reaction pathways onto the final mineral assemblage. In this case, the host initial fluid was undersaturated with respect to Fe-bearing minerals. Upon slow release of Fe at the surface of hematite, a mineral assemblage of chalcocite, bornite, and finally chalcopyrite is expected. However, in practice chalcocite did not nucleate on the surface of hematite. Rather relatively slow nucleation of bornite enabled high concentrations of Fe to build up near the dissolving hematite, so that chalcopyrite (high-sulfidation experiments) or chalcopyrite+pyrite (low sulfidation) crystallized first.

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Section: Reaction Mechanism For the Replacement Of Hematite By Chalcomentioning

confidence: 96%

Section: Reaction Mechanism For the Replacement Of Hematite By Chalcomentioning

confidence: 97%

Experimental study of the formation of chalcopyrite and bornite via the sulfidation of hematite: Mineral replacements with a large volume increase

Jing¹,

Brugger²,

Chen³

et al. 2014

American Mineralogist

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“…However, the results performed under dark observed a notable decrease than those in light below 70°C. It thus verified that visible light indeed played a role in accelerating the electron transfer process of iron dissolution, and the presence of light is more significant in prompting the dissolution of iron at low temperature, for the rate of thermal induced process was largely diminished [17,22]. Thus, it can be concluded that the dissolution of iron oxide by oxalate solution is predominated by the reductive pathway at low temperature (< 70°C), while it is predominated by the non-reductive pathway at high temperature (> 90°C).…”

Section: Illumination and Temperature (T)mentioning

confidence: 72%

“…9, iron extraction under dark could also achieve the same high efficiency (95%) as that in light if more time (25 h) was given. Thus, iron dissolution at low temperature is seen as a time-consuming process that can proceed for days, while it only needs a few hours instead of days at high temperature for the same efficiency [22].…”

Section: Illumination and Temperature (T)mentioning

confidence: 99%

Removal of iron from ilmenite by KOH leaching-oxalate leaching method

Wang

Chu

et al. 2010

Rare Metals

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Oxalic acid was used for the removal of iron from the intermediates of ilmenite leached by KOH liquor. Various parameters, such as pH, temperature, initial oxalate concentration, and illumination were investigated. Meanwhile, it was found that orthorhombic crystal Ti 2 O 2 (OH) 2 (C 2 O 4 )⋅H 2 O formed as the leaching proceeded. Scanning electronic microscope (SEM) images implied that the formation of Ti 2 O 2 (OH) 2 (C 2 O 4 )⋅H 2 O with good crystallinity proceeded through three stages. Calcining Ti 2 O 2 (OH) 2 (C 2 O 4 )⋅H 2 O, anatase (350°C) or rutile (550°C) type TiO 2 was obtained, respectively. Element analysis found that the calcined product contained 94.9% TiO 2 and 2.5% iron oxide, but only about 1600 ppm dissolvable iron oxide was left, which indicates that oxalic acid was comparatively effective on iron oxide removal from the intermediates. Finally, an improved route was proposed for the upgrading of ilmenite into rutile.

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“…The dissolution of Fe(III) plays an significant role in the cycling of Fe in aquatic systems, and iron release kinetics can be controlled by many environmental factor, including particle size (Madden, Hochella, & Luxton, 2006), pH, sunlight intensity (Song et al, 2005), oxygen, organic ligands and the incorporation with other metal ions (Alvarez, Sileo, & Rueda, 2008). Organic ligands common in water are formate, acetate, citrate and oxalate (Graedel, Mandich, & Weschler, 1986;Zuo & Hoigne, 1992), and among them, oxalate was the most effective ligand (Panias, Taxiarchou, Douni, Paspaliaris, & Kontopoulos, 1996), and it could affect iron dissolution kinetics significantly. Mobility of iron in aquatic environments can be enhanced by (1) proton-promoted dissolution that leads metal-oxygen bonds to be loosened, thus lead to iron release (Xu & Gao, 2008), (2) ligand-promoted dissolution that forms soluble Fe(III) complexes with ligands (Wang, Schenkeveld, Kraemer, & Giammar, 2015) and (3) reduction of Fe(III) to the more soluble form of Fe (II) under anoxic environment or with the presence of reductive solution (Dos Santos Afonso, Morando, Blesa, Banwart, & Stumm, 1990) It has been reported that trace metal dopant could affect iron oxide structure and properties markedly including surface specific area, particle size (Mohapatra, Anand, Das, Upadhyay, & Verma, 2002;Warner et al, 2012), crystallization (H. Ebinger & G. Schulze, 1989), zeta potential (Alvarez et al, 2015) and adsorption behavior towards phosphate (Li et al, 2016) and metal ions (Rout et al, 2014).…”

Section: Chapter I Introductionmentioning

confidence: 99%

Effects of cobalt, nickel, and manganese doping on the structure and dissolution properties of goethite and hematite

Cui¹

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Trace metal dopant in goethite and hematite are common in soils, groundwater and sediments, and have strong influence on the structure and physicochemical properties of goethite and hematite. In this work, a series of Co, Ni and Mn-doped goethites and hematites were synthesized, fully characterized by powder X-ray diffraction (XRD), and the zeta potential of samples have been measured to study their structure. The dissolution kinetics of pure and trace metal doped goethites and hematites in proton-promoted, ligandpromoted, reductive ligand-promoted solutions were also investigated. Characterization results demonstrated that trace metal dopants affect crystal unit cell parameters, increase cell volume, and decreased the relative proportion of the main crystal facet. Additionally, zeta potential measurement indicated that trace metal dopants lower the zero point of charge of oxide. The dissolution experiments showed that trace metal dopant affect metal release extent and rate coefficient of goethite and hematite. Additionally, the dissolution experiments also indicated that the presence of ligand would promote metal release from goethite and hematite. A synergistic effect of reductant and ligand on the rate and extent of goethite and hematite dissolution was possible from the observation but still need more work to identify. The results of this research facilitate better understanding of the Co, Ni and Mn substitution on the structure and properties of goethite and hematite, and their dissolution process in different aquatic systems.

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Dissolution of hematite in acidic oxalate solutions: the effect of ferrous ions addition

Cited by 28 publications

References 12 publications

Experimental study of the formation of chalcopyrite and bornite via the sulfidation of hematite: Mineral replacements with a large volume increase

Experimental study of the formation of chalcopyrite and bornite via the sulfidation of hematite: Mineral replacements with a large volume increase

Removal of iron from ilmenite by KOH leaching-oxalate leaching method

Effects of cobalt, nickel, and manganese doping on the structure and dissolution properties of goethite and hematite

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