Special Issue "Advancements in Hydrometallurgical Processing for Base and Precious Metals"

A special issue of Minerals (ISSN 2075-163X).

Deadline for manuscript submissions: closed (31 March 2016)

Special Issue Editor

Guest Editor
Prof. Dr. Francesco Veglio

Department of Industrial and Information Engineering and Economy, University of L’Aquila, via G. Gronchi 18, 67100, L’Aquila, Italy
Website | E-Mail
Interests: chemical engineering; waste management; waste treatment; hydrometallurgy; wastewater treatment; biosorption

Special Issue Information

Dear Colleagues,

Owing to the unique properties and values of base and precious metals, many technologies have been applied for their recovery from primary and secondary raw materials. Moreover, there are still many issues regarding the environmental impacts of each of the developed methodologies and the recovery degrees for the elements of interest. Hydrometallurgical technologies have found the greatest applications for the extraction of both precious and base metals. Generally, their application result in a good efficiency of recovery degree, but considering the stringent laws regarding environmental protection, the last decade has proposed and tested various new reagents that may be considered as properly. However, there is still a lack of knowledge regarding the chemistry of hydrometallurgical processes with more environmentally friendly substances, e.g., the “green reagents”. Therefore, in this Special Issue, we welcome both reviews and full length articles that will point out research improvements regarding the hydrometallurgical processing of both ores and wastes, to recover their valuable contents of base and precious metals.

Prof. Dr. Francesco Veglio
Guest Editor

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 papers will be 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 1400 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

  • primary resource
  • secondary resources
  • base metals
  • precious metals
  • hydrometallurgical procedures
  • wastes
  • recycling
  • processing
  • green reagents
  • minerals
  • management
  • characterization
  • sustainability
  • chemistry

Published Papers (5 papers)

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Research

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Open AccessArticle
Selective Leaching of Vanadium from Roasted Stone Coal by Dilute Sulfuric Acid Dephosphorization-Two-Stage Pressure Acid Leaching
Minerals 2016, 6(3), 75; https://doi.org/10.3390/min6030075
Received: 8 May 2016 / Revised: 25 June 2016 / Accepted: 8 July 2016 / Published: 21 July 2016
Cited by 5 | PDF Full-text (2764 KB) | HTML Full-text | XML Full-text
Abstract
A novel staged leaching process has been reported in this paper to selectively extract vanadium from roasted stone coal and the mechanisms have been clarified. Results showed that the leaching efficiency of V, Al, P and Fe was 80.46%, 12.24%, 0.67% and 3.12%, [...] Read more.
A novel staged leaching process has been reported in this paper to selectively extract vanadium from roasted stone coal and the mechanisms have been clarified. Results showed that the leaching efficiency of V, Al, P and Fe was 80.46%, 12.24%, 0.67% and 3.12%, respectively, under the optimum dilute sulfuric acid dephosphorization (DSAD)-two-stage pressure acid leaching (PAL) conditions. The efficient separation of V from Fe, Al and P was realized. As apatite could be leached more easily than mica, the apatite could completely react with sulfuric acid, while the mica had almost no change in the DSAD process, which was the key aspect in realizing the effective separation of V from P. Similarly, the hydrolyzation of Fe and Al could be initiated more easily than that of V by decreasing the residual acid of leachate. The alunite and iron-sulphate compound generated in the first-stage PAL process resulted in the effective separation of V from Fe and Al. Full article
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Open AccessArticle
Optimization of Acid Leaching of Rare-Earth Elements from Mongolian Apatite-Based Ore
Minerals 2016, 6(3), 63; https://doi.org/10.3390/min6030063
Received: 31 March 2016 / Revised: 1 June 2016 / Accepted: 24 June 2016 / Published: 30 June 2016
Cited by 6 | PDF Full-text (3022 KB) | HTML Full-text | XML Full-text
Abstract
Optimization of the acid leaching process for Mongolian apatite-based ore containing rare-earth elements (REEs) was studied. The ore contained approximately 10% of REEs as total rare earth oxides, and the major impurities were Ca (33% as CaO) and Fe (23% as Fe2 [...] Read more.
Optimization of the acid leaching process for Mongolian apatite-based ore containing rare-earth elements (REEs) was studied. The ore contained approximately 10% of REEs as total rare earth oxides, and the major impurities were Ca (33% as CaO) and Fe (23% as Fe2O3). Fe bearing minerals could be removed by passing the sample through a wet high-intensity magnetic separator before leaching. After magnetic separation, basic leaching tests were conducted to investigate the influence of the acid type and concentration, temperature, and the pH on the REE leaching level and kinetics. Hydrochloric acid was found to be the most effective leaching agent, leaching more than 90% of REEs in an hour. However, the concentrations of Ca ions in the leachate were also high, which would complicate recovery of the REEs. Therefore, to reduce the amount of Ca ions in the leachate, a two-stage leaching procedure was attempted. In stage 1, the sample was preleached using 1.0 M hydrochloric acid to dissolve Ca. In stage 2, the solid residue of stage 1 was leached using 2.0 M hydrochloric acid to dissolve REEs. Consequently, this two-stage leaching significantly reduced the Ca concentration in the final leachate without affecting the leaching levels of REEs. Full article
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Open AccessArticle
Modeling the Effect of Composition and Temperature on the Conductivity of Synthetic Copper Electrorefining Electrolyte
Minerals 2016, 6(3), 59; https://doi.org/10.3390/min6030059
Received: 1 March 2016 / Revised: 10 June 2016 / Accepted: 13 June 2016 / Published: 24 June 2016
Cited by 1 | PDF Full-text (3089 KB) | HTML Full-text | XML Full-text
Abstract
The physico-chemical properties of the copper electrolyte significantly affect the energy consumption of the electrorefining process and the quality of the cathode product. Favorable conditions for electrorefining processes are typically achieved by keeping both the electrolyte conductivity and diffusion coefficient of Cu(II) high, [...] Read more.
The physico-chemical properties of the copper electrolyte significantly affect the energy consumption of the electrorefining process and the quality of the cathode product. Favorable conditions for electrorefining processes are typically achieved by keeping both the electrolyte conductivity and diffusion coefficient of Cu(II) high, while ensuring low electrolyte viscosity. In this work the conductivity of the copper electrorefining electrolyte was investigated as a function of temperature (50–70 °C) and concentrations of copper (Cu(II), 40–60 g/L), nickel (Ni(II), 0–20 g/L), arsenic (As(III), 0–30 g/L) and sulfuric acid (160–220 g/L). In total 165 different combinations of these factors were studied. The results were treated using factorial analysis, and as a result, four electrolyte conductivity models were built up. Models were constructed both with and without arsenic as the presence of As(III) appeared to cause non-linearity in some factor effects and thus impacted the conductivity in more complex ways than previously detailed in literature. In all models the combined effect of factors was shown to be minor when compared to the effect of single factors. Conductivity was shown to increase when copper, nickel and arsenic concentrations were decreased and increase with increased temperature and acidity. Moreover, the arsenic concentration was shown to decrease the level of conductivity more than previously suggested in the literature. Full article
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Open AccessArticle
Ferric Sulfate Leaching of Pyrrhotite Tailings between 30 to 55 °C
Minerals 2015, 5(4), 801-814; https://doi.org/10.3390/min5040526
Received: 8 October 2015 / Revised: 5 November 2015 / Accepted: 11 November 2015 / Published: 27 November 2015
Cited by 2 | PDF Full-text (5850 KB) | HTML Full-text | XML Full-text
Abstract
Mine tailings present major environmental issues in the mining industry. However due to the depletion of high-grade sulfide ores for metal recovery, tailings could also be a potential resource for certain valuable metals. The present study investigates the potential to recover nickel from [...] Read more.
Mine tailings present major environmental issues in the mining industry. However due to the depletion of high-grade sulfide ores for metal recovery, tailings could also be a potential resource for certain valuable metals. The present study investigates the potential to recover nickel from pyrrhotite tailings. Leaching tests were performed in acidic ferric sulfate media with 0.14 wt % solids to keep the ferric concentration essentially constant. The temperature was varied between 30 and 55 °C, and the ferric concentration was in a range 0.02–0.3 M. The results showed that both temperature and ferric sulfate concentration had significant effects on the nickel extraction kinetics. The shrinking core model (SCM) was applied to the nickel extraction data. The rate controlling step was found to be product layer diffusion. The Arrhenius plot yielded an activation energy of Ea = 62.12 kJ/mol based on apparent reaction rates obtained by the SCM. The reaction order with respect to ferric ion was found to be 1 at the high concentration range. SEM images of partially leached tailings confirmed the presence of elemental sulfur around the pyrrhotite particles, which was responsible for the observed non-linear leaching kinetics (diffusion control). Full article
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Review

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Open AccessReview
Advances towards a Clean Hydrometallurgical Process for Chromite
Minerals 2016, 6(1), 7; https://doi.org/10.3390/min6010007
Received: 28 August 2015 / Revised: 11 January 2016 / Accepted: 12 January 2016 / Published: 28 January 2016
Cited by 4 | PDF Full-text (1276 KB) | HTML Full-text | XML Full-text
Abstract
Because of the acute toxicity of Cr(VI)-bearing substances, the pollution problem caused by chromite process residue has become a worldwide concern. In the view of relevant studies, the technologies based on the alkali treatment cannot fundamentally resolve the pollution problem, because the oxidation [...] Read more.
Because of the acute toxicity of Cr(VI)-bearing substances, the pollution problem caused by chromite process residue has become a worldwide concern. In the view of relevant studies, the technologies based on the alkali treatment cannot fundamentally resolve the pollution problem, because the oxidation of Cr(III) to Cr(VI) is unavoidable during chromite decomposition. In contrast, the oxidation of Cr(III) to Cr(VI) can be controlled by the sulfuric acid treatment of chromite, and the Cr(VI) pollution can be eliminated from the original source of production. Many research studies focusing on the resolutions of the key obstacles hindering the development of the sulfuric acid treatment process have been carried out, and significant progress has been achieved. In this study, a clean hydrometallurgical process without the generation of hexavalent chromium is demonstrated. First, the chromite was decomposed and leached by sulfuric acid solution in the presence of an oxidant. Then, iron was hydrothermally removed from the acid solution as the precipitate of jarosite. Finally, chromium salts were obtained by adjusting the basicity of the solution, separation and drying. With the aim of realizing industrialization, future research emphasis on the development of the sulfuric acid treatment process is proposed in this study. Full article
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