Research

Jump to: Review

25 pages, 15804 KiB

Open AccessArticle

Unlocking the Value of End-of-Life JÜLICH Solid Oxide Cell Stack Interconnect Assembly: A Combined Experimental and Thermodynamic Study on Metallic Resource Recyclability

by Jeraldine Lastam, Dmitry Sergeev, Daniel Grüner, Michael Müller and Ruth Schwaiger

Metals 2024, 14(4), 406; https://doi.org/10.3390/met14040406 - 29 Mar 2024

Viewed by 504

Abstract

The present study provides fundamental information on the resource recyclability of the interconnect assembly, i.e., the steel interconnector and the nickel meshes, from an end-of-life JÜLICH Solid Oxide Cell Stack—F10 design. The interconnector is composed of iron, chromium, and less than 4 wt.% [...] Read more.

The present study provides fundamental information on the resource recyclability of the interconnect assembly, i.e., the steel interconnector and the nickel meshes, from an end-of-life JÜLICH Solid Oxide Cell Stack—F10 design. The interconnector is composed of iron, chromium, and less than 4 wt.% of other alloying elements, mainly cobalt and manganese. Calculated blended compositions with the nickel meshes revealed their potential as a raw material in the production of 4xx, 2xx, or 3xx stainless steels. The melting behavior of the interconnect assembly was investigated under different conditions, i.e., in inert and oxidizing atmospheres, with and without the addition of slag-forming fluxes. The results demonstrated preferential oxidation of chromium in a trivalent state within the stable cubic spinel phase. Finally, the experimental results were compared with the thermodynamic equilibrium calculations based on the available databases (FToxid, SGTE, and SGPS) in FactSage 8.1 software. The calculated tendency to oxidize is in the order of Cr > Mn > Fe > Co > Ni at P(O₂) greater than 10⁻¹⁰ bar, validating the experimental results. Full article

(This article belongs to the Special Issue Recovery and Recycling of Metals from the Wastes of New Energy Industry)

► Show Figures

Figure 1

14 pages, 4130 KiB

Open AccessArticle

Selective Extraction of Lithium from Spent Lithium-Ion Manganese Oxide Battery System through Sulfating Roasting and Water-Leaching

by Jeraldiny Becker, Sebastian Will and Bernd Friedrich

Metals 2023, 13(9), 1612; https://doi.org/10.3390/met13091612 - 18 Sep 2023

Viewed by 1216

Abstract

Sulfating roasting tests were conducted with different agents to investigate lithium recovery from spent lithium-ion manganese oxide (LMO) batteries. In this study, CaSO₄ and CaCO₃ were used as reactants, and the optimal temperature, residence time, and molar fraction of CaSO₄ [...] Read more.

Sulfating roasting tests were conducted with different agents to investigate lithium recovery from spent lithium-ion manganese oxide (LMO) batteries. In this study, CaSO₄ and CaCO₃ were used as reactants, and the optimal temperature, residence time, and molar fraction of CaSO₄ in a static reactor were determined. In the experiments, the temperature ranged between 620 and 720 °C, and the holding time was between 10 and 40 min. In addition, the molar fraction of CaSO₄ varied between 0 and 100%, with the rest being CaCO₃. The water leaching was fixed at an S/L ratio of 1/20 and heated to 60 °C for 1 h. The maximum Li yield achieved was 93.4% at 720 °C, 25 min, and a 0.5 molar fraction of CaSO₄, and virtually no Mn was present in the solution. Therefore, high selectivity for Mn—which is the major compound in the LMO black mass—was observed. Regarding statistical evaluation, temperature was the most influential parameter and, to a lesser extent, the molar fraction of CaSO₄. The product displayed a sintering effect, suggesting that the pyrolyzed black mass and reactive underwent a solid-solid reaction in the selected temperature range. Full article

(This article belongs to the Special Issue Recovery and Recycling of Metals from the Wastes of New Energy Industry)

► Show Figures

Figure 1

14 pages, 4298 KiB

Open AccessArticle

Leaching Kinetics of Hemimorphite with 5-Sulfosalicylic Acid

by Yaohong Li, Shuming Wen, Jing Cao, Dandan Wu and Yijie Wang

Metals 2023, 13(7), 1249; https://doi.org/10.3390/met13071249 - 08 Jul 2023

Viewed by 722

Abstract

The kinetics of leaching zinc from hemimorphite was investigated. The factors that influence hemimorphite leaching were also evaluated, and a kinetic model was built. In addition, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) was used to investigate the changes of surface morphology before and [...] Read more.

The kinetics of leaching zinc from hemimorphite was investigated. The factors that influence hemimorphite leaching were also evaluated, and a kinetic model was built. In addition, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) was used to investigate the changes of surface morphology before and after leaching. By decreasing particle size and increasing temperature, 5-sulfosalicylic acid concentration, and stirring speed, the leaching rate of hemimorphite can be enhanced. The shrinkage nucleus model describes the surface chemistry of leaching. The activation energy of hemimorphite by 5-sulfosalicylic acid in the leaching process was determined as 55.244 kJ/mol. The reaction rate based on the shrinkage nucleus model can be expressed by the semi-empirical formula:

{1 - (1 - x)}^{1 / 3} = [k_{0} {(C)}^{0.3385} ({r_{0})}^{- 0.6083} ({SS)}^{0.4992} \exp (- 55.244 / RT)] t

. At the condition of 50 °C of leaching temperature, 0.175 mol/L of 5-sulfosalicylic acid concentration, 82.5 μm of particle size and 650 rpm of stirring speed, the high leaching rates of zinc were obtained. After the reaction time of 15 min, the leaching rate of zinc reached more than 95%. According to the SEM-EDS results, the hemimorphite and leaching residue are distributed in blocks, but the particle size of the leaching residue is smaller, and the atomic concentrations of Zn and Si in the leaching residue are significantly lower than those in the hemimorphite, so the leaching effect is remarkable. Therefore, 5-sulfosalicylic acid solution would be an excellent leaching agent for zinc extraction from hemimorphite. Full article

(This article belongs to the Special Issue Recovery and Recycling of Metals from the Wastes of New Energy Industry)

► Show Figures

Figure 1

15 pages, 6644 KiB

Open AccessArticle

Purification of Waste Graphite from Crucibles Used in Photovoltaic Crystallization by an Alkali-Acid Method

by Yonghang Zhang, Zhengjie Chen, Keqiang Xie, Xiaowei Chen, Yiyou Hu and Wenhui Ma

Metals 2023, 13(7), 1180; https://doi.org/10.3390/met13071180 - 25 Jun 2023

Cited by 3 | Viewed by 1581

Abstract

The photovoltaic industry generates large amounts of waste graphite (WG) that contains useful metals that can be recycled into high-value products. This study elucidated the impurity elements and their existence states in WG, analyzed and verified the source of the main impurity phase [...] Read more.

The photovoltaic industry generates large amounts of waste graphite (WG) that contains useful metals that can be recycled into high-value products. This study elucidated the impurity elements and their existence states in WG, analyzed and verified the source of the main impurity phase SiC, and determined the SiC content to be 4.66%. WG was purified using an alkaline-acid method, whose optimal process parameters were a solid alkali ratio of 3, calcination temperature of 600 °C, calcination time of 120 min, HCl concentration of 1 M, and acid leaching time of 40 min. Under these conditions, a graphite product with a fixed carbon content of 98.45% was obtained. Impurities were determined to migrate via three pathways: (1) Most main elements (Al, K, and Si) in silicates were removed by alkaline roasting, while the remaining elements were dissolved in acid. (2) Impurities containing metal elements such as Fe, Mg, Ca, and Zn were decomposed in NaOH to form hydroxides or oxides that were dissolved in HCl. (3) Silicon carbide impurities were removed by the alkaline-acid method without decomposition and often existed with graphite in the acid-leaching slag. Full article

(This article belongs to the Special Issue Recovery and Recycling of Metals from the Wastes of New Energy Industry)

► Show Figures

Figure 1

12 pages, 2787 KiB

Open AccessArticle

Purification of Organosilicon Waste Silicon Powder with Hydrometallurgy

by Liping Zhao, Zuyu Li, Fengshuo Xi, Shaoyuan Li, Wenhui Ma, Jijun Wu and Kuixian Wei

Metals 2023, 13(5), 950; https://doi.org/10.3390/met13050950 - 14 May 2023

Cited by 2 | Viewed by 1207

Abstract

Waste silicon powder produced during the production process of organosilicon materials is a major environmental concern that can lead to pollution and resource wastage. As a result, it is crucial to find efficient ways of recovering and utilizing this waste material. In this [...] Read more.

Waste silicon powder produced during the production process of organosilicon materials is a major environmental concern that can lead to pollution and resource wastage. As a result, it is crucial to find efficient ways of recovering and utilizing this waste material. In this study, the morphology of waste silicon powder was systematically studied, and an optimized purification method was proposed based on a hydrometallurgical process and phase analysis. The complex composition of waste silicon powder presents a significant challenge during its recycling. However, the results of this study showed that metal-assisted chemical etching (MACE), followed by mixed acid system leaching, is the most effective method for removing impurities from the material. The superior order of different acid systems for removing metallic impurities was HCl < HF < HF + HCl < HF + H₂O₂ < CuACE. It is worth noting that CuACE treatment has a remarkable ability to remove more than 95% of Fe through hydrometallurgy. Full article

(This article belongs to the Special Issue Recovery and Recycling of Metals from the Wastes of New Energy Industry)

► Show Figures

Figure 1

13 pages, 2747 KiB

Open AccessArticle

The States and Properties of Germanium in Sulfuric Acid Solution

by Leiting Song, Haokai Di, Ming Liang, Yan Hong, Yiner Zeng, Kun Yang and Libo Zhang

Metals 2023, 13(5), 852; https://doi.org/10.3390/met13050852 - 26 Apr 2023

Cited by 2 | Viewed by 1515

Abstract

In recent years, with the development of science and technology, the strategic position of germanium is becoming more and more important, and the global demand for germanium is also increasing. At present, there is no unified description of the existence form of germanium [...] Read more.

In recent years, with the development of science and technology, the strategic position of germanium is becoming more and more important, and the global demand for germanium is also increasing. At present, there is no unified description of the existence form of germanium in solutions. Based on the current mainstream acid leaching process of germanium, this paper studies the existing form and properties of germanium in sulfuric acid solutions. Through the characterization and analysis of Raman, FTIR, and XPS of three concentrations of pure germanium solution, it is clear that germanium mainly exists in the form of H₂GeO₃ and some Ge⁴⁺ in sulfuric acid solution. Through the Tyndall effect and zeta potential, it is determined that H₂GeO₃ exists in the form of colloid in sulfuric acid solution. With the increase of germanium concentration, H₂GeO₃ will polymerize in a sulfuric acid solution to form polygermanic acid, and the H₂GeO₃ colloidal dispersion system becomes more stable. This study clarifies the existing form and properties of germanium in sulfuric acid solution, which is of great significance to the leaching extraction of germanium-containing materials and the development of the germanium industry. Full article

(This article belongs to the Special Issue Recovery and Recycling of Metals from the Wastes of New Energy Industry)

► Show Figures

Figure 1

12 pages, 5567 KiB

Open AccessArticle

Effect of Silicon Wafer Surface Stains on Copper-Assisted Chemical Etching

by Liang Ma, Xiuhua Chen, Chenggui Tang, Shaoyuan Li, Fengshuo Xi, Huayan Lan, Wenhui Ma and Yuanchih Chang

Metals 2023, 13(4), 742; https://doi.org/10.3390/met13040742 - 11 Apr 2023

Viewed by 1681

Abstract

Silicon wafer slicing is a crucial process during solar cell fabrication, but it often stains the silicon wafer surface. Thus, this work systematically investigated the composition, source, and cleaning method of typical white spot stains on silicon wafer surfaces. The EDS and XPS [...] Read more.

Silicon wafer slicing is a crucial process during solar cell fabrication, but it often stains the silicon wafer surface. Thus, this work systematically investigated the composition, source, and cleaning method of typical white spot stains on silicon wafer surfaces. The EDS and XPS results showed that the white spot stains contained CaCO₃ and SiO₂ that were consistent with the filler components in sticky silicon ingot glue. The effects of stains on copper deposition and copper-assisted chemical etching were studied. White spot stains remained attached to the silicon surface after deposition and etching. These stains affected the uniform deposition of copper particles on the surface of the silicon wafer and also impeded the catalytic etching of copper particles. Finally, KOH solution was combined with an ultrasonic field to remove surface stains from the silicon wafer. This study provides important guidance for the removal of silicon wafer contaminants to fabricate high-efficiency solar cells. Full article

(This article belongs to the Special Issue Recovery and Recycling of Metals from the Wastes of New Energy Industry)

► Show Figures

Figure 1

12 pages, 4915 KiB

Open AccessArticle

Hg/Se/PbSO₄ Recovery by Microwave-Intensified HgSe Pyrolysis from Toxic Acid Mud

by Hanlin Zeng, Peng Liu, Yan Hong, Kun Yang and Libo Zhang

Metals 2022, 12(6), 1038; https://doi.org/10.3390/met12061038 - 17 Jun 2022

Cited by 1 | Viewed by 1376

Abstract

The acid mud produced in the nonferrous smelting process is a hazardous waste, which mainly consists of elements Hg, Se, and Pb. Valuable metal (Hg/Se/Pb) can be recovered from acid mud by heat treatment. For safe disposal of the toxic acid mud, a [...] Read more.

The acid mud produced in the nonferrous smelting process is a hazardous waste, which mainly consists of elements Hg, Se, and Pb. Valuable metal (Hg/Se/Pb) can be recovered from acid mud by heat treatment. For safe disposal of the toxic acid mud, a new resource utilization technology by microwave roasting is proposed in this paper. The reaction mechanisms were revealed through thermodynamics and thermogravimetric analysis, which showed that the main reaction was the oxidative pyrolysis of HgSe in the process of roasting. Moreover, the mercury removal effects of acid mud by microwave heating and conventional heating were studied, the recovery rate of mercury by microwave heating for 30 min at 400 °C was 99.5%: far higher than that of conventional heating for 30 min at 500 °C (44.3%). This was due to the high dielectric constant of HgSe, as microwaves can preferentially heat HgSe and reduce the adsorption energy of HgSe on the surface of PbSO₄ blocks, thus strengthening the pyrolysis process of HgSe and reducing energy consumption. The preferable prototyping technology for resource utilization of toxic acid mud should be microwave roasting. This study is of great significance for the realization of mercury pollution reduction and for green production of lead-zinc smelting. Full article

(This article belongs to the Special Issue Recovery and Recycling of Metals from the Wastes of New Energy Industry)

► Show Figures

Figure 1

Review

Jump to: Research

27 pages, 5493 KiB

Open AccessReview

Processing of Metal Waste—Sludge from the Galvanizing Plants

by Jaromír Drápala, Hana Rigoulet, Silvie Brožová, Jitka Malcharcziková, Šárka Langová, Jiřina Vontorová, Václav Nétek, Jaroslav Kubáč and Dominik Janáček

Metals 2022, 12(11), 1947; https://doi.org/10.3390/met12111947 - 14 Nov 2022

Cited by 1 | Viewed by 2139

Abstract

This paper deals with the possibility of obtaining zinc from waste galvanic sludge, which is formed during galvanic plating. The aim of the experimental and practical part was to obtain zinc after the leaching of galvanic sludge. Leaching was performed in sulfuric acid, [...] Read more.

This paper deals with the possibility of obtaining zinc from waste galvanic sludge, which is formed during galvanic plating. The aim of the experimental and practical part was to obtain zinc after the leaching of galvanic sludge. Leaching was performed in sulfuric acid, nitric acid and hydrochloric acid at different temperatures and time intervals with the addition of oxidizing agents as hydrogen peroxide or ozone. A separation of the leach and filtrate using filtration followed. The leach was further processed by a precipitation of iron and other metals using various agents. After a further filtration, the electrolysis was performed in order to obtain pure zinc on the cathode at the electrical voltage of approximately 3.5 V. Leaching using a solution of sodium hydroxide or potassium hydroxide was also performed when the prior dissolving of a major part of zinc into the leach occurred, while iron and non-ferrous metals remained in the leaching residue. After the filtration of the leach, the electrolysis with a high zinc yield of a purity of more than 99% followed. This way seems to be an optimal one for building a semi-industrial line for galvanic sludge recycling. All the partial products, i.e., the leach, the leaching residue, the filtrate, the solid precipitate and the separated metal on the cathode were subjected to chemical analyses. The analyses results are presented in tables and graphs. Full article

(This article belongs to the Special Issue Recovery and Recycling of Metals from the Wastes of New Energy Industry)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Recovery and Recycling of Metals from the Wastes of New Energy Industry

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Published Papers (9 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI