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Moving towards the Crystal Structure, Molecular or Atomic-Scale for Green...
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Moving towards the Crystal Structure, Molecular or Atomic-Scale for Green and Novel Hydrometallurgical Processing

A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Mineral Processing and Extractive Metallurgy".

Deadline for manuscript submissions: closed (16 November 2021) | Viewed by 35010

Special Issue Editors

Dr. Yousef Ghorbani

E-Mail Website
Guest Editor
College of Health and Science, School of Chemistry, University of Lincoln, Homelet, Green Lane, Joseph Banks Laboratories, Lincolnshire, Lincoln LN6 7DL UK
Interests: gaining access to high-tech and critical raw materials: understanding the factors that drive and limit extractive metallurgy; electrochemistry and materials characterization: moving toward crystal structure, molecular formula, and atomic scale; synthetic crystals as a replacement for critical raw materials; enhancement of overall process performance and energy/material utilization: a move toward dry laboratories and data bank
Prof. Dr. Shenxu Bao

E-Mail Website
Guest Editor
School of Resources and Environmental Engineering, Wuhan University of Technology 122# Luoshi Road, Wuhan 430070, China
Interests: hydrometallurgy; purification and separation of metals in aqueous solution; treatment and utilization of solid waste
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Future-oriented and sustainable innovations in mineral extraction are required to allow economic extraction of metals from lower-grade and more complex ores. Hydrometallurgical technologies have shown the greatest potential for metal extraction from both primary and secondary raw material resources. The metal extraction steps are typically characterized by approaches that range from leaching of metal values by chemical reagents or bacterial action at ambient or elevated pressures and temperatures in reactors to leaching in vats or heaps (both chemical and biological) to in situ recovery. Although hydrometallurgical approaches have had many processes and technological developments at different front lines, there is still a lack of knowledge regarding the chemistry of hydrometallurgical processes, mineral and reagent interactions, and the involved electrochemistry. Whereas much has been observed at the macroscale regarding hydrometallurgical processes, it is clear that future-oriented and sustainable innovation in hydrometallurgy for more selective and environmentally friendly process development requires moving towards the crystal structure or molecular or atomic scale in minerals and reagents. These can only be convincingly tackled by the application of the state of the art tools and techniques through near-atomic-scale analytical and structural approaches, which may include, but are not limited to, quantum chemical modeling, PEEM/SPEM, nano-XRF, TEM, AFM, X-ray crystallography (XRC), and 3DEM.

For this Special Issue, we welcome both reviews and full-length articles. Of particular interest are articles that demonstrate how the crystal structure or molecular or atomic scale in minerals and reagents are a driving factor in developing future technological advances and sustainably innovative solutions in hydrometallurgy towards unlocking the use of potential raw materials from primary and secondary metal resources.

Prof. Dr. Yousef Ghorbani
Prof. Dr. Shenxu Bao
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Minerals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • hydro- and biohydro-metallurgy
  • crystal structure
  • molecular or atomic scale
  • electrochemistry
  • ores and leach chemistry
  • reaction chemistry
  • gangue chemistry
  • mineral characterization
  • analytical approaches
  • foreign ions and ionic strength
  • reagent consumption by gangue minerals
  • heap leaching
  • atmospheric oxidation
  • pressure oxidation
  • oxidative leaching
  • removal of impurities
  • solution purification
  • solvent extraction and electrowinning (SX-EW)
  • adsorption and IX processes
  • eco-friendly processes
  • green reagents
  • strategic and critical metals
  • precious metals
  • critical elements
  • primary resources
  • secondary resources

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Published Papers (8 papers)

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Research

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9 pages, 3515 KiB  
Article
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 2956
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  
Article
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 - 9 Dec 2021
Cited by 7 | Viewed by 4405
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  
Article
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 1821
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  
Article
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 9 | Viewed by 2372
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  
Article
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 8 | Viewed by 2809
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  
Article
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 17 | Viewed by 8616
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  
Article
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 19 | Viewed by 4107
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  
Review
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 28 | Viewed by 6581
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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