Oxidative leaching of refractory sulphidic gold tailings with an ionic liquid

Teimouri, Samaneh; Potgieter, J.H.; Simate, Geoffrey S.; Dyk, L. Van; Dworzanowski, M.

doi:10.1016/j.mineng.2020.106484

Cited by 15 publications

(9 citation statements)

References 36 publications

(50 reference statements)

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“…It is well known that hydrometallurgical processes, and leaching in particular, are absolutely dependent on the shrinking core model, liberation, and particle size distribution (PSD). The leaching kinetics of the selected size fraction was described in detail recently by Teimouri et al (2020), who established that there were two regions of kinetic control, i.e. mixed control and diffusion control, with activation energies E a of 17.97 kJ/mol and 27.17 kJ/mol, respectively.…”

Section: Mineral Tailings and Characterizationmentioning

confidence: 99%

Using experimental design and response surface methodology (RSM) to optimize gold extraction from refractory sulphidic gold tailings with ionic liquids

Teimouri

Mawire

Potgieter

et al. 2020

J. S. Afr. Inst. Min. Metall.

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This work examined the feasibility of gold extraction from a pyrite flotation concentrate sample using an ionic liquid and water mixture as solvent, thiourea complexing agent, and iron(III) sulphate oxidant. A design of experiment (DOE) methodology was used to optimize the process parameters. The purpose of the investigation was to determine how feasible it would be to replace the traditional cyanide extraction process by using an alternative approach, and compare the yield that could be obtained with a less environmentally damaging and hazardous combination of chemicals. Test parameters such as ionic liquid concentration, pulp density, time, and temperature were varied using two imidazolium-based ionic liquids: 1-butyl-3-methylimidazolium hydrogen sulphate [Bmim + HSO 4-] and 1-butyl-3-methylimidazolium trifluoromethansulphonate [Bmim + CF 3 SO 3-]. The effects on gold extraction were assessed and screened using a half fractional factorial design (2 5-1) approach. The ionic liquid concentration, pulp density, and temperature had a statistically significant effect on gold extraction, while the type of ionic liquid and extraction time did not affect the gold extraction as much within the operating range investigated. A high gold extraction was obtained at low ionic liquid concentration, low pulp density, and high temperature. A central composite design in conjunction with response surface methodology were used to create an optimization design with the statistically significant parameters in an attempt to establish the optimal gold extraction conditions. It was found that the optimum concentration of ionic liquid [Bmim + HSO 4-] in the aqueous solution was 15% (v/v), pulp density was 15% (w/v), and the temperature 60°C, with a gold extraction of 35.7% under these conditions. This, sadly, was only about half of the yield achieved with the cyanide process. In order to compete with the traditional approach, a way will have to be found to completely destroy the pyrite component in the material, in which a substantial portion of the gold was locked up. This work, and similar studies reported in the literature, indicates that cyanide technology for gold recovery will remain the process of choice in the gold industry for the immediate future.

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Section: Mineral Tailings and Characterizationmentioning

confidence: 99%

Using experimental design and response surface methodology (RSM) to optimize gold extraction from refractory sulphidic gold tailings with ionic liquids

Teimouri

Mawire

Potgieter

et al. 2020

J. S. Afr. Inst. Min. Metall.

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“…Depending on the mineralogy of materials, a high amount of solid in the leaching solution can sometimes contribute to ineffective mixing within the solution. This is due to the higher-density mixture causing ineffective dispersion and mass transfer within the mixture [ 32 , 33 , 34 , 35 ]. With a high amount of solid in the mixture, the amount of the ionic liquid solution can also be a limiting reagent in the dissolution reaction.…”

Section: Resultsmentioning

confidence: 99%

A New Hydrometallurgical Process for Metal Extraction from Electric Arc Furnace Dust Using Ionic Liquids

et al. 2022

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This research proposes a new hydrometallurgical method for Zn, In, and Ga extraction, along with Fe as a common impurity, from electric arc furnace dust (EAFD), using ionic liquids. EAFD is a metal-containing waste fraction generated in significant amounts during the process of steelmaking from scrap material in an electric arc furnace. With valuable metal recovery as the main goal, two ionic liquids, [Bmim+HSO4−] and [Bmim+Cl−], were studied in conjunction with three oxidants: Fe2(SO4)3, KMnO4, and H2O2. The results indicated that the best combination was [Bmim+HSO4−] with [Fe2(SO4)3]. An experimental series subsequently demonstrated that the combination of 30% v/v [Bmim+HSO4−], 1 g of [Fe2(SO4)3], S/L ratio = 1/20, a 240 min leaching time, and a temperature of 85 °C was optimal, resulting in maximum extractions of 92.7% Zn, 97.4% In, and 17.03% Ga. In addition, 80.2% of the impurity metal Fe was dissolved. The dissolution kinetics of these four elements over a temperature range of 55–85 °C was found to be diffusion controlled. The remaining phases present in the leached residue were low amounts of ZnO, Fe3O4, ZnFe2O4, and traces of Ca(OH)2 and MnO2, and additional sharp peaks indicative of PbSO4 and CaSO4 appeared within the XRD pattern. The intensity of the peaks related to ZnO and Fe3O4 were observed to have decreased considerably during leaching, whereas some of the refractory ZnFe2O4 phase remained. SEM-EDS analysis revealed that the initial EAFD morphology was composed of spherical-shaped fine-grained particle agglomerates, whereas the leached residue was dominated by calcium sulphate (Ca(SO4))-rich needle-shaped crystals. The results clearly demonstrate that [Bmim+HSO4−] is able to extract the target metals due to its acidic properties.

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“…To do this, the mechanically activated samples for 10 h were investigated at various leaching times (4, 8, 12, 16, 20, and 24 h), as shown in Figure 3. It was observed that 87.73% of Au was leached after 20 h. Also, the dissolution rate at the start of the leaching time (4 and 16 h) was much higher than at the end of the cycle, which can be linked to the further concentration of reactants concerning the dissolute products beginning of the reaction [34]. Based on Figure 3, 20 h was selected as the optimum time for optimizing of the other practical parameters.…”

Section: Resultsmentioning

confidence: 99%

Mechanism and kinetics of gold leaching from copper anode slime using BmimHSO₄ as green solvent

Hernashki

Rezvani

Khayati

et al. 2022

Int J of Chemical Kinetics

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The cyanide process, as the most common approach in the recovery of gold by hydrometallurgical, suffers from its high toxicity to the environment. The effect of practical parameters, viz., temperature, time, concentration, mechanical activation, and the stirring rate, was investigated using a combination of H 2 O 2 , BmimHSO 4 , and thiourea as green solvent to recover the gold from anode copper slime in an electrorefining plant. The leaching kinetics of Au in the selected slime was also investigated. The results showed that leaching reaches 93.48% after 20 h in the activated sample for 10 h at the temperature of 313.15 K and solvent including 60% (v/v) BmimHSO 4 , 50 g/L thiourea, 1/15 g/ml pulp density, 25 g/L H 2 O 2 , and an agitation speed of 400 rpm. Moreover, the leaching of Au follows the shrinkage particle model, and the diffusion of a solvent through the leaching product was the administrated mechanism. The proposed green solvent can also dissolve gold effectively and is an excellent candidate to replace harmful cyanide-based solvents.

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Oxidative leaching of refractory sulphidic gold tailings with an ionic liquid

Cited by 15 publications

References 36 publications

Using experimental design and response surface methodology (RSM) to optimize gold extraction from refractory sulphidic gold tailings with ionic liquids

Using experimental design and response surface methodology (RSM) to optimize gold extraction from refractory sulphidic gold tailings with ionic liquids

A New Hydrometallurgical Process for Metal Extraction from Electric Arc Furnace Dust Using Ionic Liquids

Mechanism and kinetics of gold leaching from copper anode slime using BmimHSO₄ as green solvent

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Oxidative leaching of refractory sulphidic gold tailings with an ionic liquid

Cited by 15 publications

References 36 publications

Using experimental design and response surface methodology (RSM) to optimize gold extraction from refractory sulphidic gold tailings with ionic liquids

Using experimental design and response surface methodology (RSM) to optimize gold extraction from refractory sulphidic gold tailings with ionic liquids

A New Hydrometallurgical Process for Metal Extraction from Electric Arc Furnace Dust Using Ionic Liquids

Mechanism and kinetics of gold leaching from copper anode slime using BmimHSO4 as green solvent

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Mechanism and kinetics of gold leaching from copper anode slime using BmimHSO₄ as green solvent