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Minerals
Special Issues
Mechanochemical Effect in Mineral Processing, Environmental Remediation and Recycling
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Mechanochemical Effect in Mineral Processing, Environmental Remediation and Recycling

A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Crystallography and Physical Chemistry of Minerals & Nanominerals".

Deadline for manuscript submissions: closed (20 November 2019) | Viewed by 13150

Special Issue Editor

Prof. Dr. Chiharu Tokoro

E-Mail Website
Guest Editor
Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan
Interests: mineral processing; recycling; wastewater treatment; separation; powder simulation; geochemical modeling
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues

About 20 years ago, mechanochemistry made its debut in the field of mineral processing. Since then, several high-intensity grinding methods were developed to enhance the extraction of metals from refractory minerals and ores. The large amount of energy exchanged in the mill chamber was proven effective at inducing not only physical but also chemical modifications in the minerals. Although the phenomena responsible for these chemical modifications are simply referred as “mechanochemical reaction”, their nature is complex, as it can go from simple lattice distortions to real conversion reactions. Now that processing refractory minerals and recycling has become crucial, investigating the mechanochemical activation and its mechanisms represents a matter of scientific and technological relevance.

This Special Issue aims to publish papers describing the mechanochemical effect associated with the use of high-intensity grinding methods. Works addressing the following topics will be given the highest consideration: (i) the isolation and assessment of the phenomena contributing to the mechanochemical activation and/or reaction of ores/minerals; (ii) the applicability of mechanochemical reactions to fields other than mineral processing (e.g., recycling, environmental remediation); (iii) the simulation and optimization of grinding operations, as well as the development of grinding systems to induce mechanochemical reactions in minerals.

Prof. Chiharu Tokoro
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 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

  • Mechanochemical reaction
  • Microstrain
  • Lattice distortions
  • In-chamber conversion
  • Leaching
  • Kinetics
  • Recycling
  • Activated environmental materials
  • Simulations

Published Papers (4 papers)

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Research

10 pages, 2917 KiB  
Article
Synthesis of Geopolymers from Mechanically Activated Coal Fly Ash and Improvement of Their Mechanical Properties
by Mitsuaki Matsuoka, Kaho Yokoyama, Kohei Okura, Norihiro Murayama, Masato Ueda and Makio Naito
Minerals 2019, 9(12), 791; https://doi.org/10.3390/min9120791 - 16 Dec 2019
Cited by 12 | Viewed by 2591
Abstract
Coal fly ash is a spherical fine powder by-product discharged from coal-fired power plants. When coal fly ash is used as raw materials for the synthesis of geopolymers, there are practical problems associated with the stable surface of the particles that do not [...] Read more.
Coal fly ash is a spherical fine powder by-product discharged from coal-fired power plants. When coal fly ash is used as raw materials for the synthesis of geopolymers, there are practical problems associated with the stable surface of the particles that do not allow the production of geopolymers with sufficient strength. A long-time is also required for the curing. In this study, we aim to promote the curing reaction of geopolymers by activating the surface of coal fly ash particles. By mechanically activating the surface of coal fly ash particles using an attrition-type mill, the dissolution of Si4+ and Al3+ in coal fly ash is promoted, and the acceleration of the reaction taking place during curing is also anticipated. The surface morphology and crystal phase of coal fly ash particles change with the use of an attrition-type mill. The mechanical activation results in improvement of the compressive strength and the acid resistance under milder curing conditions by the densification of the hardened body. Thus, it is clearly shown that mechanical activation is effective for the production of geopolymers with beneficial mechanical properties under milder curing conditions. Full article
(This article belongs to the Special Issue Mechanochemical Effect in Mineral Processing, Environmental Remediation and Recycling)
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12 pages, 3775 KiB  
Article
Effects and Mechanism of Different Grinding Media on the Flotation Behaviors of Beryl and Spodumene
by Zhenfeng Hu and Chuanyao Sun
Minerals 2019, 9(11), 666; https://doi.org/10.3390/min9110666 - 29 Oct 2019
Cited by 8 | Viewed by 2694
Abstract
The flotation behavior of beryl and spodumene (typical silicate minerals) was studied at wet-grinding conditions with different grinding mediums, with dodecylamine or sodium oleate as the collector. The mechanism of potential influence of the grinding medium to the flotation behavior was investigated through [...] Read more.
The flotation behavior of beryl and spodumene (typical silicate minerals) was studied at wet-grinding conditions with different grinding mediums, with dodecylamine or sodium oleate as the collector. The mechanism of potential influence of the grinding medium to the flotation behavior was investigated through measuring zeta potential of pure minerals, micro scanning by X-ray photoelectron spectroscopy (XPS), surface interaction simulation and etc. The test data suggested that, with dodecylamine as the collector and relatively lower pH, the recoveries of beryl and spodumene are higher with zircon balls as wet-grinding media than those with iron balls, while in the higher pH, the recovery difference became smaller. With sodium oleate as a collector, within the same pH environment, the recovery of beryl and spodumene under zircon ball wet-grinding is lower than those under iron wet-grinding. We observed formation of iron-hydroxyl complexes on the mineral surface after iron ball grinding, which are significant influence on the flotation behavior of silicate minerals. Furthermore, for iron wet-grinding, the iron adsorbed on the mineral surface increased the adsorption energy between laurylamine (cationic collector) and silicate minerals, which inhibited the interaction between collectors and minerals. On the other hand, the interaction energy between sodium oleate (anion collector) and silicate minerals was decreased, which promoted the interaction between collectors and minerals. Full article
(This article belongs to the Special Issue Mechanochemical Effect in Mineral Processing, Environmental Remediation and Recycling)
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10 pages, 1744 KiB  
Article
Mechanochemical Treatment to Remove Arsenic from Copper Ore
by Shingo Ishihara, Kozo Shinoda and Junya Kano
Minerals 2019, 9(6), 349; https://doi.org/10.3390/min9060349 - 6 Jun 2019
Cited by 2 | Viewed by 2752
Abstract
This study tested the removal of arsenic from copper ore concentrate via a mechanochemical treatment by planetary ball milling. The harmful components of ore, such as arsenic, are increasing year by year and decreasing the copper grade, therefore there is a strong need [...] Read more.
This study tested the removal of arsenic from copper ore concentrate via a mechanochemical treatment by planetary ball milling. The harmful components of ore, such as arsenic, are increasing year by year and decreasing the copper grade, therefore there is a strong need to improve the separation of arsenic from copper ore. The effect of grinding as a result of chemical activation caused by mechanochemical treatment was evaluated by XRD and X-ray absorption spectroscopy (XAS) measurements. From the results of the XRD analysis, several crystalline minerals were identified from the original samples. The diffraction peaks of the original samples were reduced by grinding, although grinding did not generate any new diffraction peaks. The comparison of the results of grinding in dry and wet conditions showed that the rate of disappearance of the crystalline minerals was faster in dry grinding than in wet grinding. To clarify the chemical state of arsenic in copper ore, XAS analysis was carried out. The results indicated that the arsenic compound changed from sulfide, in the original sample, to oxide after grinding. As a result of oxidation, the arsenic was easy to dissolve in a water and alkaline solution, and optimized dry and wet grinding conditions achieved up to 76% arsenic removal efficiency. Full article
(This article belongs to the Special Issue Mechanochemical Effect in Mineral Processing, Environmental Remediation and Recycling)
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12 pages, 3555 KiB  
Article
Structural Change Analysis of Cerianite in Weathered Residual Rare Earth Ore by Mechanochemical Reduction Using X-Ray Absorption Fine Structure
by Tatsuya Kato, Yuki Tsunazawa, Wenying Liu and Chiharu Tokoro
Minerals 2019, 9(5), 267; https://doi.org/10.3390/min9050267 - 30 Apr 2019
Cited by 9 | Viewed by 4535
Abstract
Prolonged high-intensity grinding can modify the crystal structure of solid substances and/or induce chemical reaction, which is referred to as mechanochemical reaction. Such reactions can exert positive influences on hydrometallurgical processes, therefore, many researchers have applied mechanochemical reactions for metals dissolution from minerals. [...] Read more.
Prolonged high-intensity grinding can modify the crystal structure of solid substances and/or induce chemical reaction, which is referred to as mechanochemical reaction. Such reactions can exert positive influences on hydrometallurgical processes, therefore, many researchers have applied mechanochemical reactions for metals dissolution from minerals. The mechanism of mechanochemical reaction has been investigated using solid analyses and simulations. Structural changes caused by mechanochemical reactions are not yet sufficiently clarified because the ground samples are amorphous. The objective of this study was to analyze structural changes of cerianite in weathered residual rare earth ore by mechanochemical reduction. The ore was ground by planetary ball milling for 10, 60 and 720 min. Structural change was analyzed by the X-ray absorption near-edge structure and extended x-ray absorption fine structure analysis at the cerium LIII- and K-edges. These analyses revealed that the structural change of cerianite in this ore induced by mechanochemical reduction involved oxygen vacancy production. The process of the oxygen vacancy formation was closely coupled with the quantum effect of localization–delocalization of the 4f electron of cerium. Full article
(This article belongs to the Special Issue Mechanochemical Effect in Mineral Processing, Environmental Remediation and Recycling)
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