Acidic dissolution of hematite: Kinetic and thermodynamic investigations with oxalic acid

Salmimies, Riina; Mannila, Marju; Kallas, Juha; Häkkinen, Antti

doi:10.1016/j.minpro.2012.04.001

Cited by 34 publications

(29 citation statements)

References 9 publications

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“…To study the reaction kinetics, another set of experiments was conducted with optimized (determined statistically) parameters (which were the organic acid type, concentration of acid and duration of leaching), where maximum metal recovery was attained. The procedure followed was similar to that mentioned above; from separate 250 mL Erlenmeyer flasks, samples were withdrawn at intervals of 20 min to 3 h. The isothermal models tested in this study are presented in Equations

α^{2} = kt Parabolic (D_{1})

α + (1 - α) \ln (1 - α) = kt Valensi Barrer (D_{2})

1 - 2 / 3 α - {((), 1 - α)}^{2 / 3} = kt Ginstling Brounsthein (D_{3})

{([], 1 - {(1 - α)}^{1 true/ 3})}^{2} = kt Jander (D_{4})

{([], {(1 + α)}^{1 true/ 3} - 1)}^{2} = kt Anti Jander (D_{5}, ...)

…”

Section: Methodsmentioning

confidence: 99%

Optimization of process parameters and dissolution kinetics of nickel and cobalt from lateritic chromite overburden using organic acids

Biswas

Chakraborty

Chaudhuri

et al. 2014

J of Chemical Tech & Biotech

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BACKGROUND: Leaching kinetics of the roasted (at 600• C) chromite overburden of Sukinda mines Orissa, India, was studied with optimized data generated through response surface methodology (RSM) coupled with Box-Behnken design (BBD). The effects of oxalic, citric and gluconic acid concentration (50-150 mmol L −1 ), reaction temperature (60 • to 80• C) and period (up to 3 h) on metal (nickel and cobalt) dissolution were examined.

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α^{2} = kt Parabolic (D_{1})

α + (1 - α) \ln (1 - α) = kt Valensi Barrer (D_{2})

1 - 2 / 3 α - {((), 1 - α)}^{2 / 3} = kt Ginstling Brounsthein (D_{3})

{([], 1 - {(1 - α)}^{1 true/ 3})}^{2} = kt Jander (D_{4})

{([], {(1 + α)}^{1 true/ 3} - 1)}^{2} = kt Anti Jander (D_{5}, ...)

…”

Section: Methodsmentioning

confidence: 99%

Optimization of process parameters and dissolution kinetics of nickel and cobalt from lateritic chromite overburden using organic acids

Biswas

Chakraborty

Chaudhuri

et al. 2014

J of Chemical Tech & Biotech

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“…This is especially important for ions such as Fe and AI. The chemical reactions of citric and oxalic acid with the oxides of iron, aluminium and calcium can be drawn as follows (Salmimies et al, 2012;Hernández et al, 2013) Fungi interact with minerals and synthesize an array of organic compounds that have been shown to affect the mobility of metal ions. Their biological activity was high and dependent on the production of organic acids, such as citric and oxalic acids.…”

Section: Bioleaching With Fungimentioning

confidence: 99%

Bioleaching of Lodan quartz using Aspergillus ficuum

Handayani¹

2017

IMJ

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Depending on its purity, quartz has a wide application in industry. Fungi play an important role in the quartz purification. A bioleaching study of Lodan quartz sample from Rembang, Central Java was conducted to obtain a suitable raw material for industrial applications. The microbial process using selected-indigenous fungus of Aspergillus ficuum in terms of removing iron, aluminum, and other unwanted metals within quartz. The result was then compared to the chemical leaching using pure citric and oxalic acids. The bioleaching process removed the iron (Fe2O3) from the initial content (0.78%) in the original sand sample to reach a level of 0.013% Almost 98.3% iron was removed. The bioleaching test also removed the aluminum, manganese, chrome, and titanium to a very low level within the 12-day process. The iron content in this treated quartz met the standards for optical and high-quality glass. On the other hand, the chemical leaching using pure citric and oxalic acids concentrations were equal to those that were produced by A. ficuum could only removed 70.5% of iron around 0.23% iron and 0,29 % aluminium were still remained in the sand. This fact suggested that the bioleaching method is more effective than the chemical one using the organic acids. The use of fungi to remove iron from quartz has the potential to be an effective method for upgrading the content and the commercial value of the quartz. The experimental results of this study have provided significant opportunity to use biotechnological approach for producing the quartz as a feed material for the highquality glass industry.

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“…Each of these processes can control the overall dissolution rate depending on the crystal shape and size distribution as well as on the type of solvent. Several theoretical models were developed in the literature to describe dissolution kinetics in crystalline materials [23,24]. These mechanistic models are characteristic of a crystalline system and depend on the crystal size distribution, shape, and constituents.…”

Section: Theoretical Modeling Of Dissolution Kineticsmentioning

confidence: 99%

An investigation on the chemical stability and a novel strategy for long-term stabilization of diphenylalanine nanostructures in aqueous solution

et al. 2015

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a b s t r a c tThe stability of diphenylalanine (FF) microwires and microtubes in phosphate buffer solution was investigated and a novel strategy was developed for their chemical stabilization. This stability investigation was carried out by optical microscopy and by high performance liquid chromatography (HPLC). These microstructures dissolve in the solution depending upon their degree of FF saturation. The dissolution mechanisms of the structures in kinetically limited processes were found by accurately fitting the experimental dissolution data to a theoretical kinetic equation. The dissolution data were well fitted to the particular Avrami-Erofe'ev kinetic expression (R 2 > 0.98). These findings suggest that the structures can be stabilized by a decrease in the hydration of the constituent molecules thorough a chemical conformational induced transition upon heat treatment. The stable microtubes were fabricated in a novel three step procedure consisting of the reduction of silver ions in unstable FF microtubes by a citrate reductant, the stabilization by chemical conformational induced transition upon heat treatment, and the consequent oxidation of the reduced silver by a persulfate oxidant. These materials were characterized by electron microscopy and powder X-ray diffraction techniques. The long-term stability of both structures was also confirmed by optical microscopy and HPLC.

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Acidic dissolution of hematite: Kinetic and thermodynamic investigations with oxalic acid

Cited by 34 publications

References 9 publications

Optimization of process parameters and dissolution kinetics of nickel and cobalt from lateritic chromite overburden using organic acids

Optimization of process parameters and dissolution kinetics of nickel and cobalt from lateritic chromite overburden using organic acids

Bioleaching of Lodan quartz using Aspergillus ficuum

An investigation on the chemical stability and a novel strategy for long-term stabilization of diphenylalanine nanostructures in aqueous solution

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