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Metals
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EARTH 2022-Green Technologies for Resources Processing and Circulation
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EARTH 2022-Green Technologies for Resources Processing and Circulation

A special issue of Metals (ISSN 2075-4701). This special issue belongs to the section "Extractive Metallurgy".

Deadline for manuscript submissions: closed (30 June 2023) | Viewed by 10624

Special Issue Editors

Prof. Dr. Hsing-I Hsiang

E-Mail Website
Guest Editor
Department of Resources Engineering, National Cheng Kung University, Tainan 70101, Taiwan
Interests: ceramics; ceramic processing; soft magnetic composites; electroceramics
Dr. Jun-Yi Wu

E-Mail Website
Guest Editor
Department of Intelligent Automation Engineering, National Chin-Yi University of Technology, Taichung 411030, Taiwan
Interests: resources recovery; mineral processing; hydrometallurgy; wastewater containing heavy metals and solid waste recycling and reutilization

Special Issue Information

Dear Colleagues,

The 16th EARTH Symposium (EARTH 2022) is the premier international congress in the field of resources circulation. The main objective is to foster knowledge transfer and exchange experience among delegates with academic and industrial backgrounds.

Our goal is to share with all participants the latest knowledge on recent advances in resources processing, hydrometallurgy, pyrometallurgy, organic-inorganic metallic materials processing, and other important topics related to the environment and resources and metallic materials recycling.

Because of the limited resources and environmental hazards caused by exploitation, resources circulation from secondary sources is critical today. If human beings can recover resources from wastes efficiently, it can not only increase the value of wastes but also decrease the exploitation of ores or natural resources.  Therefore, suitable techniques applied to recover resources from secondary sources or reuse/recycle wastes are the optimal options for future generations. This Special Issue aims to introduce the new technologies of resources processing, hydrometallurgy, pyrometallurgy, organic-inorganic material processing, and resources circulation throughout East Asia (Korea, Japan, Taiwan, China, and Thailand) and beyond.

Prof. Dr. Hsing-I Hsiang
Dr. Jun-Yi Wu
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. Metals 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 2600 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

  • resources processing
  • hydrometallurgy
  • pyrometallurgy
  • organic-inorganic material processing
  • resources circulation

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Published Papers (5 papers)

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Research

11 pages, 1709 KiB  
Article
Influences and Isotherm Models on Phosphorus Removal from Wastewater by Using Fe3+-Type UBK10 Cation Exchange Resin as Absorbent
by Onchanok Juntarasakul, Monthicha Rawangphai, Theerayut Phengsaart and Kreangkrai Maneeintr
Metals 2023, 13(7), 1166; https://doi.org/10.3390/met13071166 - 23 Jun 2023
Cited by 2 | Viewed by 1535
Abstract
Phosphorus is a nutrient that is required for life. Eutrophication, on the other hand, is caused by an overabundance of phosphorus in the hydrosphere. Eutrophication is a form of water pollution that can be solved by removing phosphorus from the environment. Adsorption with [...] Read more.
Phosphorus is a nutrient that is required for life. Eutrophication, on the other hand, is caused by an overabundance of phosphorus in the hydrosphere. Eutrophication is a form of water pollution that can be solved by removing phosphorus from the environment. Adsorption with cation exchange resin is a more practical method for removing phosphate ions at low concentrations than traditional approaches. The column approach is good for recovering phosphate effectively. As a result, a superior adsorption ability of the column and a practical regeneration process are critical. Accordingly, the goal of this study is to design a phosphate ion recovery system using a Fe-type cation exchange resin (Fe3+-type UBK 10) column. The batch approach was used to investigate the characteristics influencing the adsorption of phosphate ions on Fe-type UBK 10 in order to better comprehend the mechanism of adsorption. The number of phosphate ions adsorbed increased with increasing reaction time, according to the findings. The best results were achieved using 3 g of resin in 0.05 M NaCl at pH 6. The best fit was found in the Langmuir isotherm using equilibrium data. Full article
(This article belongs to the Special Issue EARTH 2022-Green Technologies for Resources Processing and Circulation)
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13 pages, 3427 KiB  
Article
Leaching Efficiency and Kinetics of Platinum from Spent Proton Exchange Membrane Fuel Cells by H2O2/HCl
by Wei-Sheng Chen, Wei-Shr Liu and Wei-Chung Chen
Metals 2023, 13(6), 1006; https://doi.org/10.3390/met13061006 - 23 May 2023
Cited by 7 | Viewed by 2134
Abstract
The increasing carbon emissions from various fossil fuels have led to the search for efficient and clean energy sources to replace them. Proton exchange membrane fuel cells (PEMFCs) are a promising alternative, but the use of platinum as a catalyst material poses challenges [...] Read more.
The increasing carbon emissions from various fossil fuels have led to the search for efficient and clean energy sources to replace them. Proton exchange membrane fuel cells (PEMFCs) are a promising alternative, but the use of platinum as a catalyst material poses challenges due to its limited resources and low abundance. This study proposes an efficient method for platinum recovery while retaining spent membranes. The membrane and catalyst were separated using isopropanol, and the spent membrane was dissolved in a 50% ethanol solution to prepare the precursor for subsequent membrane regeneration. Hydrochloric acid (HCl) was used as the leaching agent, and the experimental parameters such as HCl concentration, H2O2 concentration, contact time, and operating temperature were optimized to achieve the highest platinum leaching rate. Finally, through isothermal leaching experiments, the leaching mechanism was investigated using the shrinking core model, indicating the involvement of both surface chemical and inner diffusion mechanisms in the platinum leaching process, primarily controlled by the inner diffusion mechanism. Under optimal conditions, the platinum leaching rate was about 90%, and the activation energy of the reaction was calculated to be 6.89 kJ/mol using the Arrhenius equation. Full article
(This article belongs to the Special Issue EARTH 2022-Green Technologies for Resources Processing and Circulation)
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10 pages, 2607 KiB  
Article
Re-Synthesis of CIGS Nanocrystallites Using Oxidation Roasting Pretreatment from Spent CIGS Targets
by Hsing-I Hsiang, Chih-Cheng Chen and Chung-Yen Chiang
Metals 2023, 13(5), 893; https://doi.org/10.3390/met13050893 - 5 May 2023
Cited by 2 | Viewed by 1557
Abstract
The CIGS (Cu(In, Ga)Se2) thin film solar cell sputtering process utilizes only 30% of the original target. The remaining 70% of the target must be recycled to achieve In, Ga, and Se rare metal sustainable use. It is, therefore, very important [...] Read more.
The CIGS (Cu(In, Ga)Se2) thin film solar cell sputtering process utilizes only 30% of the original target. The remaining 70% of the target must be recycled to achieve In, Ga, and Se rare metal sustainable use. It is, therefore, very important to establish spent CIGS target recycling technology to reduce environmental damage. CIGS is a tetrahedrally bonded semiconductor with a chalcopyrite crystal structure. Chalcopyrite is resistant to attack by the oxidants used in dissolution due to forming a passivation surface layer. Therefore, increasing the reaction temperature, lixiviating agent, and oxidant concentrations is necessary to enhance CIGS dissolution. The oxidation roasting pretreatment effects on the recovery and leaching of spent CIGS targets are investigated in this study. The results indicated that the proper oxidation roasting pretreatment process could significantly enhance CIGS leaching, reducing costs and increasing the reaction rate. This can be explained by the fact that the chalcopyrite structure was decomposed and transformed into easier dissolvable Cu2SeO4, In2O3, and amorphous Ga2O3 after roasting in the air. Cu, In, and Ga recoveries can reach above 99.9% by leaching CIGS roasted at 500 °C in 1 M H2SO4 at 60 °C for 1 h. As the roasting temperature was increased to 600 °C, the Ga recovery rate decreased due to the formation of difficult dissolvable β-Ga2O3. Mono-dispersed, near-stoichiometric CIGS nanoparticles with a mean crystallite size of 9 nm can be obtained using a direct recycling process combining oxidation, leaching, and re-synthesis processes. Full article
(This article belongs to the Special Issue EARTH 2022-Green Technologies for Resources Processing and Circulation)
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11 pages, 1728 KiB  
Article
Leaching of Sm, Co, Fe, and Cu from Spent SmCo Magnets Using Organic Acid
by Jian-Zhi Wang, Yi-Chin Tang and Yun-Hwei Shen
Metals 2023, 13(2), 233; https://doi.org/10.3390/met13020233 - 26 Jan 2023
Cited by 7 | Viewed by 1932
Abstract
In this study, the Taguchi method was used to investigate the effect of citric acid and malic acid on the leaching of SmCo magnet waste. First, we used a L16(45) orthogonal table to conduct experiments. Second, we conducted a [...] Read more.
In this study, the Taguchi method was used to investigate the effect of citric acid and malic acid on the leaching of SmCo magnet waste. First, we used a L16(45) orthogonal table to conduct experiments. Second, we conducted a factor effect analysis on the experimental results of the orthogonal table to understand the influence of temperature, acid concentration, solid–to–liquid ratio, time, and hydrogen peroxide on the leaching efficiency and we obtained the priority order of the factors affecting the leaching efficiency. The priorities of citric acid and malic acid were H2O2 > temperature > S/L > time > acid and temperature > time > S/L > H2O2 > acid, respectively. Finally, the optimal leaching parameters were obtained through confirmation experiments. For optimal leaching rates with citric acid, the amount of hydrogen peroxide (H2O2) added was 2.0 vol.%, the temperature was 90 °C, the S/L ratio was 5 g L−1, the time was 135 min and the acid concentration was 1.0 mol L−1, resulting in leaching efficiencies of Sm, Co, Fe, and Cu of 87.62, 93.82, 97.10, and 92.84%, respectively. For optimal leaching rates with malic acid, the temperature was 80 °C, the time was 75 min, the S/L ratio was 7.5 g L−1, the amount of hydrogen peroxide added was 3.5 vol.%, and the acid concentration was 1.5 mol L−1, resulting in leaching efficiencies of Sm, Co, Fe, and Cu of 75.18, 74.58, 82.42, and 1.35%, respectively. Full article
(This article belongs to the Special Issue EARTH 2022-Green Technologies for Resources Processing and Circulation)
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11 pages, 3540 KiB  
Article
Separation of Cobalt, Samarium, Iron, and Copper in the Leaching Solution of Scrap Magnets
by Jian-Zhi Wang, Yi-Hsun Hsieh, Yi-Chin Tang and Yun-Hwei Shen
Metals 2023, 13(1), 90; https://doi.org/10.3390/met13010090 - 31 Dec 2022
Cited by 11 | Viewed by 2376
Abstract
With the growing awareness of protecting the urban environment and the increasing demand for strategic materials, recycling of SmCo magnets has become imperative. This paper provides a series of methods regarding the available hydrometallurgical technologies for recycling scrap magnets. This study aimed to [...] Read more.
With the growing awareness of protecting the urban environment and the increasing demand for strategic materials, recycling of SmCo magnets has become imperative. This paper provides a series of methods regarding the available hydrometallurgical technologies for recycling scrap magnets. This study aimed to recover samarium (Sm), cobalt (Co), copper (Cu), and iron (Fe) from acid leachate of SmCo scrap by using precipitation and ion exchange. IRC748 showed a good adsorption capacity for Fe and Cu. Elution tests were conducted using sulfuric acid at the concentration of 2N as eluents. Precipitation was performed first using a selective chemical precipitation method, and the Sm was first precipitated as a sodium samarium sulfate powder. Then, the samarium-deprived solution was placed in the beaker, and the addition of oxalic acid promoted cobalt oxalate precipitation. Furthermore, the leachate, which is rich in Cu and Fe, was mixed with oxalic acid to obtain the copper oxalate precipitation. This study successfully recovered SmCo magnets through ion exchange and precipitants. Full article
(This article belongs to the Special Issue EARTH 2022-Green Technologies for Resources Processing and Circulation)
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