Research

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9 pages, 3515 KiB

Open AccessArticle

Sulfuric Acid Granulation of Copper—Nickel Ore Tailings: Leaching of Copper and Nickel in the Presence of Sulfide Oxidation Activators

by Andrey Goryachev, Anton Svetlov, Alena Kompanchenko and Dmitriy Makarov

Minerals 2022, 12(2), 129; https://doi.org/10.3390/min12020129 - 23 Jan 2022

Cited by 3 | Viewed by 2454

Abstract

A laboratory scale study was conducted, aimed at finding an effective method for processing fine concentration tailings of copper-nickel ores. A sulfuric acid tailing granulation process followed by subsequent heap leaching of granules is proposed. Various methods of preparation and storage of the [...] Read more.

A laboratory scale study was conducted, aimed at finding an effective method for processing fine concentration tailings of copper-nickel ores. A sulfuric acid tailing granulation process followed by subsequent heap leaching of granules is proposed. Various methods of preparation and storage of the granular material are discussed. A solution of sulfuric acid was used as a binder. It was found that the addition of an oxidizing agent (Fe³⁺ and NO₂⁻) when irrigating the granules had an effect on the recovery of metals. Changes in the recovery performance of non-ferrous metals into solution were studied under subsequent heap leaching of the material during a period of positive temperatures. The role of nitrogen compounds, in particular, nitrous acid, on the recovery of metals into solution after the preliminary storage of granules at below 0 °C temperatures is also discussed. Full article

(This article belongs to the Special Issue Moving towards the Crystal Structure, Molecular or Atomic-Scale for Green and Novel Hydrometallurgical Processing)

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17 pages, 4535 KiB

Open AccessArticle

Extraction of Ta and Nb from a Coltan Bearing Ore by Means of Ammonium Bifluoride Fluorination and Sulfuric Acid Leaching

by Alidor Shikika, Francois Zabene, Fabrice Muvundja, Mac C. Mugumaoderha, Julien L. Colaux, Mohamed Aatach and Stoyan Gaydardzhiev

Minerals 2021, 11(12), 1392; https://doi.org/10.3390/min11121392 - 09 Dec 2021

Cited by 5 | Viewed by 3640

Abstract

A novel approach for Ta and Nb extraction consisting of the pre-treatment of a coltan-bearing ore with an ammonium bifluoride sub-molten salt and subsequent acid leaching has been studied. The effects from ore granulometry, ammonium bifluoride (ABF) to ore mass ratio, temperature and [...] Read more.

A novel approach for Ta and Nb extraction consisting of the pre-treatment of a coltan-bearing ore with an ammonium bifluoride sub-molten salt and subsequent acid leaching has been studied. The effects from ore granulometry, ammonium bifluoride (ABF) to ore mass ratio, temperature and duration of fluorination on the degree of Ta and Nb extraction were examined. The ABF to ore ratio and process temperature were found to have the most pronounced impact on extraction efficiency. The following optimal process conditions were determined: ore granulometric fraction (−75 + 45 µm), ABF-ore (5/1), fluorination temperature (200 °C) and fluorination time (2.5 h). Maintaining these parameters enabled about 94% of Ta and 95% of Nb to be brought into solution during the sulfuric-acid-leaching stage. A comparison of the proposed method with previously reported studies suggests that due to the effects of mechanical agitation and the recirculation of the HF-containing gaseous phase back into the process, the dosage rate of ABF at the fluorination stage could be reduced significantly without sacrificing the overall recovery of Ta and Nb. In such a way, the approach could offer added environmental benefits since release of fluoride-containing effluents into the environment could be limited. Full article

(This article belongs to the Special Issue Moving towards the Crystal Structure, Molecular or Atomic-Scale for Green and Novel Hydrometallurgical Processing)

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17 pages, 6532 KiB

Open AccessArticle

Separation and Stabilization of Arsenic from Lead Slime by the Combination of Acid Leaching and Forming Scorodite

by Wenhua Li, Wei Liu, Hongwei Liu, Huanlong Wang and Wenqing Qin

Minerals 2021, 11(12), 1319; https://doi.org/10.3390/min11121319 - 26 Nov 2021

Cited by 1 | Viewed by 1390

Abstract

In this paper, a scheme is proposed for the treatment of arsenic-containing lead slime by the combination of acid pressure oxidation leaching and forming scorodite. On the basis of thermodynamic calculations, the effects of six factors including acid concentration, oxygen partial pressure ( [...] Read more.

In this paper, a scheme is proposed for the treatment of arsenic-containing lead slime by the combination of acid pressure oxidation leaching and forming scorodite. On the basis of thermodynamic calculations, the effects of six factors including acid concentration, oxygen partial pressure (pO₂), liquid to solid ratio (L/S), agitating speed, leaching time and temperature for the removal of arsenic were studied in an acid pressure oxidation leaching process, then the optimum leaching conditions were established: L/S of 10 mL/g, leaching time of 2.5 h, pO₂ of 2.0 MPa, leaching temperature of 170 °C, acid concentration of 100 g/L and stirring speed of 300 r/min. Under the optimal conditions, the leaching rate of arsenic from lead slime reached 99.10% and the arsenic content of the leaching residue was about 0.80%. After a decontamination procedure, the total arsenic concentration in the acid solution obtained from leaching experiments was 37.18 g/L, and the initial pH was 0.50. Finally, as high as 98.5% of arsenic extracted from the lead slime was stabilized in the form of scorodite (FeAsO₄·2H₂O) by the precipitation process under the following conditions: initial pH value of 1.0, Fe(II)/As molar ratio of 1.3, pO₂ of 2.5 MPa, temperature of 160 °C and precipitation time of 2.0 h. Full article

(This article belongs to the Special Issue Moving towards the Crystal Structure, Molecular or Atomic-Scale for Green and Novel Hydrometallurgical Processing)

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17 pages, 4299 KiB

Open AccessArticle

Structural Characterization and Adsorption Capability of Carbonaceous Matters Extracted from Carbonaceous Gold Concentrate

by Huiqun Niu, Hongying Yang and Linlin Tong

Minerals 2021, 11(1), 23; https://doi.org/10.3390/min11010023 - 28 Dec 2020

Cited by 6 | Viewed by 1928

Abstract

In this paper, the structures of element carbon and humic acid extracted from carbonaceous gold concentrate were characterized employing a variety of analytical methods. The extracted amounts of ECE (elemental carbon extract) and HAE (humic acid extract) were 14.84–38.50 and 11.55–28.05 mg g [...] Read more.

In this paper, the structures of element carbon and humic acid extracted from carbonaceous gold concentrate were characterized employing a variety of analytical methods. The extracted amounts of ECE (elemental carbon extract) and HAE (humic acid extract) were 14.84–38.50 and 11.55–28.05 mg g⁻¹, respectively. SEM and porosity analysis indicated that ECE occurred mostly as irregular blocky particles with a mesoporous surface with the average pore diameter being 31.42 nm. The particle size of ECE was mainly ranged from 5.5 to 42 μm and the specific surface area was 20.35 m² g⁻¹. The physicochemical features and structure of ECE were close to activated carbon, and the crystallinity was slightly lower than graphite. The particle size distribution of HAE varied from 40 to 400 nm with the specific surface area of 42.84 m² g⁻¹, whereas the average pore diameter of HAE was 2.97 nm. FTIR and UV–VIS analyses indicated that HAE was a complex organic compound containing the enrichment of oxygen-containing structure. The results showed that the adsorption amounts of ECE and HAE under the acidic conditions were 470.46 and 357.60 mg g⁻¹, respectively. In an alkaline environment, the amount of ECE was 449.02 mg g⁻¹ and the value of HAE was 294.72 mg g⁻¹. ECE mainly utilized the outer surface and mesoporous structure to adsorb gold, while the functional groups’ complexation or surface site adsorption was the leading approach for HAE to adsorb gold. Full article

(This article belongs to the Special Issue Moving towards the Crystal Structure, Molecular or Atomic-Scale for Green and Novel Hydrometallurgical Processing)

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27 pages, 15266 KiB

Open AccessArticle

Quantitative X-ray µCT Measurement of the Effect of Ore Characteristics on Non-Surface Mineral Grain Leaching

by Mahdi Ghadiri, Susan T.L. Harrison and Marijke A. Fagan-Endres

Minerals 2020, 10(9), 746; https://doi.org/10.3390/min10090746 - 23 Aug 2020

Cited by 6 | Viewed by 2413

Abstract

In heap (bio)leaching processes, a substantial fraction of the valuable mineral is positioned below the ore particle surface. X-ray micro-computed tomography (μCT) was used to quantify the effect of ore type and structure and operating temperature on the leaching of this mineral, to [...] Read more.

In heap (bio)leaching processes, a substantial fraction of the valuable mineral is positioned below the ore particle surface. X-ray micro-computed tomography (μCT) was used to quantify the effect of ore type and structure and operating temperature on the leaching of this mineral, to investigate the rate-controlling factors. Mini-leaching columns containing agglomerated chalcopyrite, pyrite, and malachite ores were scanned by X-ray μCT (13.40 µm resolution) at select time intervals. The leaching of a relatively porous malachite ore was reaction-controlled, with no leaching penetration limitation into the ore particles. For two less porous ore types, the structure and higher porosity of the agglomerate rim and conditions that resulted in the degradation of the full ore matrix structure were found to be the determining variables of the leaching extent and time. In the case of a chalcopyrite ore, an enhancement of copper recovery and sulphide mineral dissolution with increasing temperature was attributable to the increased leaching penetration distance and crack development in addition to thermodynamically expected increased leaching rate. Increasing temperature did not affect the maximum penetration distance for the waste rock containing pyrite, with no crack development observed. Overall increases in iron recovery were due to accelerated leaching rates, though diffusion or mineral access limitations were evident at a higher temperature. Full article

(This article belongs to the Special Issue Moving towards the Crystal Structure, Molecular or Atomic-Scale for Green and Novel Hydrometallurgical Processing)

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22 pages, 5053 KiB

Open AccessEditor’s ChoiceArticle

High-Performance Recovery of Cobalt and Nickel from the Cathode Materials of NMC Type Li-Ion Battery by Complexation-Assisted Solvent Extraction

by Wen-Yu Wang, Hong-Chi Yang and Ren-Bin Xu

Minerals 2020, 10(8), 662; https://doi.org/10.3390/min10080662 - 26 Jul 2020

Cited by 11 | Viewed by 7328

Abstract

The annual global volume of waste lithium-ion batteries (LIBs) has been increasing over years. Although solvent extraction method seems well developed, the separation factor between cobalt and nickel is still relatively low—only 72 when applying conventional continuous-countercurrent extraction. In this study, we improved [...] Read more.

The annual global volume of waste lithium-ion batteries (LIBs) has been increasing over years. Although solvent extraction method seems well developed, the separation factor between cobalt and nickel is still relatively low—only 72 when applying conventional continuous-countercurrent extraction. In this study, we improved the separation factor of cobalt and nickel by complexation-assisted solvent extraction. Before solvent extraction procedure, leaching kinetic of Li, Ni, Co and Mn was studied and can be explained by the Avrami equation. Leached residues were also investigated by SEM and XRD. Operation parameters of complexation-assisted solvent extraction were examined, including volume ratio of extractant to diluent, types of diluent, type of complexing reagent, extractant saponification percentage and volume ratio of organic phase to aqueous phase. The optimal separation factor of complexation-assisted solvent extraction could be improved to 372, which is five times that of conventional solvent extraction. The separation tendency would be interpreted by the relationship between extraction equilibrium pH and log distribution coefficient. Full article

(This article belongs to the Special Issue Moving towards the Crystal Structure, Molecular or Atomic-Scale for Green and Novel Hydrometallurgical Processing)

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14 pages, 3468 KiB

Open AccessArticle

Use of Seawater/Brine and Caliche’s Salts as Clean and Environmentally Friendly Sources of Chloride and Nitrate Ions for Chalcopyrite Concentrate Leaching

by Pía Hernández, Alexis Dorador, Monserrat Martínez, Norman Toro, Jonathan Castillo and Yousef Ghorbani

Minerals 2020, 10(5), 477; https://doi.org/10.3390/min10050477 - 23 May 2020

Cited by 17 | Viewed by 3459

Abstract

A less harmful approach for the environment regarding chalcopyrite concentrate leaching, using seawater/brine and caliche’s salts as a source of chloride and nitrate ions, was investigated. Different variables were evaluated: sulfuric acid concentration, sodium nitrate concentration, chloride concentration, source of water (distilled water, [...] Read more.

A less harmful approach for the environment regarding chalcopyrite concentrate leaching, using seawater/brine and caliche’s salts as a source of chloride and nitrate ions, was investigated. Different variables were evaluated: sulfuric acid concentration, sodium nitrate concentration, chloride concentration, source of water (distilled water, seawater, and brine), temperature, concentrate sample type, nitrate source (analytical grade and industrial salt), and pre-treatment methods in order to obtain maximum copper extraction. All tests were performed at moderate temperatures (≤45 °C) and atmospheric pressure. The leaching system using distilled water, seawater, and brine base media resulted in copper extraction of 70.9%, 90.6%, and 86.6% respectively. The leaching media, with a concentration of 20 g/L Cl⁻, obtained a maximum Cu extraction of 93.5%. An increase in the concentration of H₂SO₄ and NaNO₃ from 0.5 to 0.7 M, led to an increase in the copper extraction. The use of an industrial salt compared to the analytical salt did not show great variations in the percentage of extraction achieved, which would be a good and cost effective alternative. The increase in temperature from 25 to 45 °C showed a great effect on the copper leaching (of 60% until 90.6%, respectively). The pre-treatment is suggested to increase copper extraction from 60.0% to 71.4%. Full article

(This article belongs to the Special Issue Moving towards the Crystal Structure, Molecular or Atomic-Scale for Green and Novel Hydrometallurgical Processing)

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Review

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14 pages, 3499 KiB

Open AccessEditor’s ChoiceReview

Specific Refractory Gold Flotation and Bio-Oxidation Products: Research Overview

by Richmond K. Asamoah

Minerals 2021, 11(1), 93; https://doi.org/10.3390/min11010093 - 19 Jan 2021

Cited by 24 | Viewed by 5778

Abstract

This paper presents a research overview, reconciling key and useful case study findings, towards uncovering major causes of gold refractoriness and maximising extraction performance of specific gold flotation and bio-oxidation products. Through systematic investigation of the ore mineralogical and gold deportment properties, leaching [...] Read more.

This paper presents a research overview, reconciling key and useful case study findings, towards uncovering major causes of gold refractoriness and maximising extraction performance of specific gold flotation and bio-oxidation products. Through systematic investigation of the ore mineralogical and gold deportment properties, leaching mechanisms, and kinetic behaviour and pulp rheology, it was observed that the predominant cause of the poor extraction efficacy of one bio-oxidised product is the presence of recalcitrant sulphate minerals (e.g., jarosite and gypsum) produced during the oxidation process. This was followed by carbonaceous matter and other gangue minerals such as muscovite, quartz, and rutile. The underpining leaching mechanism and kinetics coupled with the pulp rheology were influenced by the feed mineralogy/chemistry, time, agitation/shear rate, interfacial chemistry, pH modifier type, and mechano-chemical activation. For instance, surface exposure of otherwise unavailable gold particles by mechano-chemical activation enhanced the gold leaching rate and yield. This work reflect the remarkable impact of subtle deposit feature changes on extraction performance. Full article

(This article belongs to the Special Issue Moving towards the Crystal Structure, Molecular or Atomic-Scale for Green and Novel Hydrometallurgical Processing)

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