• Resources Recycling
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• v.31 no.1
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• pp.21-28
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• 2022

The smelting reduction of spent lithium-ion batteries results in metallic alloys of cobalt, nickel, and copper. To develop a process to separate the metallic alloys, leaching of the metallic mixtures of these three metals with H₂SO₄ solution containing 3% H₂O₂ dissolved all the cobalt and nickel, together with 9.6% of the copper. Cyanex 301 selectively extracted Cu(II) from the leaching solution, and copper ions were completely stripped with 30% aqua regia. Selective extraction of Co(II) from a Cu(II)-free raffinate was possible using the ionic liquid ALi-SCN. Three-stage cross-current stripping of the loaded ALi-SCN by a 15% NH₃ solution resulted in the complete stripping of Co(II). A process was proposed to separate the three metal ions from the sulfuric acid leaching solutions of metallic mixtures by employing solvent extraction.

• Resources Recycling
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• v.28 no.6
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• pp.36-45
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• 2019

The spent petroleum catalysts contain rare metals such as vanadium, nickel, molybdenum, and cobalt. Therefore, the leaching of these rare metals from spent petroleum catalysts by organic acid was investigated in the present study. The leaching efficiency of metals by organic acid was in the following order: oxalic acid > tartaric acid > citric acid > maleic acid > ascorbic acid. Among the organic acids employed in this work, oxalic acid can be considered to be superior to the other acids in terms of metals leaching efficiency. The effect of several leaching conditions such as temperature, acid concentration, pulp density, stirring speed, and reaction time on the leaching of metals was investigated. Vanadium and molybdenum were selectively dissolved by oxalic acid from the spent catalysts. The leaching kinetics of vanadium by oxalic acid was also investigated. An activation energy of 8.76 kJ/mol indicated that the leaching kinetics of vanadium by oxalic acid solution was controlled by mass transfer.

• Journal of the Korean Ceramic Society
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• v.35 no.4
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• pp.392-398
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• 1998

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.563-568
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• 2003

Recently, the recycled amount of electric, mechanical parts, and appliances in artifacts has increased. These products use valuable rare metals such as platinum group metals and gold, which are included occasionally as additives. Rare metals are maldistributed in the world and most of them are produced in small quantities. A small amount of rare metals used in the appliances causes a large loss of rare metal resources because of the lack of an economically recycling method. The present recycling technologies including physical and chemical separation methods that are considered for recycling of electric, mechanical parts and appliances.

• Resources Recycling
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• v.23 no.3
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• pp.51-60
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• 2014

In this study, the domestic supply & demand of the raw materials of 35 rare metals was analyzed categorized as four types - ores, metals, compounds and scraps. Foreign trade volumes of the raw materials of rare metals have been steadily increased, furthermore, recently trade growth rate highly exceeds GDP. The raw materials of rare metals - silicon, nickel, molybdenum, manganese, etc. - for steel industry were the most big part of the raw materials of rare metals trade, while the raw materials of rare metals for electronics industry were imported relatively small volumes less than $100 million. However systematic supply & demand management on the raw materials of rare metals for electronics industry is needed since recently growth rate per year has been remarkably high over 20%. Import volumes were about three times bigger than export scale, and most of the raw materials of rare metals were traded as a metal form.

• Resources Recycling
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• v.30 no.6
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• pp.36-42
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• 2021

Spent lithium-ion batteries are treated by reduction-smelting at high temperatures to recover valuable metals. Solvent extraction and precipitation of the HCl leaching solution of reduction-smelted metallic alloys resulted in a filtrate containing Ni(II) and a small amount of Si(IV). Adsorption and precipitation experiments were conducted to recover pure Ni(II) compounds from the filtrate. Si(IV) was selectively loaded onto polyacrylamide, but this method did not efficiently filter the solution due to an increase in viscosity. The addition of Na₂CO₃ as a precipitant to the filtrate led to the simultaneous precipitation of Ni(II) and Si(IV). However, it was possible to recover nickel oxalate with a purity higher than 99.99% by selectively precipitating Ni(II) with the addition of Na₂C₂O₄ as a precipitant.

• Analytical Science and Technology
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• v.8 no.4
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• pp.449-456
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• 1995

Novel macrocyclic ligands modified with pendant arms, N, N', N'', N''', N'''', N'''''-hexakis(2-aminoethyl)-1, 4, 7, 10, 13, 16-hexaazacyclootadecane [$L_3$, Fig.1] and 1, 4, 7-tris(3-(o-hydroxyphenyl)propyl)-1, 4, 7-triazacyclononane [$L_4$, Fig.1] have been synthesized, and the protonation of $L_3$ and $L_4$ and stability constants of $L_3$ with bivalent transition metal ions and rare earth metal ions were determined by a potentiometry. The obtained results show that the complex formation of $L_3$ depends on the metal ligand ratios, and the stability of the metal complexes does not depend on the sizes of the metal ions, but on the nature of the metal ions. The structures of the rare earth complexes for $L_4$ were characterized by an X-ray absorption spectrometry(XAFS).

• Resources Recycling
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• v.27 no.3
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• pp.66-77
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• 2018

The import amount of rare metal in Korea is about 6,034 million USD, but the self-sufficiency of rare metals is about only 1%. In order to secure the stable supply of rare metals, it is necessary to operate an efficient stockpile system. In this study, we established a system to assess the adequacy of stockpiles by quantifying the risk factors of tangible and intangible risks in order to establish an efficient stockpile strategy. The model developed in this study aims to select the rare metals that need to be stockpiled first and to suggest the direction of the stockpiling policy in accordance with technological change and market change from the mid and long term viewpoint. The evaluation results derived from the model can quantitatively measure the security level of each rare metal and enable relative comparison between the rare metals using criticality matrix. Therefore, it is expected that more efficient stockpile policy will be possible if the proposed model is utilized in the future policy making.

• Journal of the Korean Ceramic Society
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• v.55 no.6
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• pp.527-555
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• 2018

High-temperature thermal insulation materials challenge extensive oxide candidates such as porus $SiO_2$, $Al_2O_3$, yttria-stabilized zirconia, and mullite, due to the needs of good mechanical, thermal, and chemical reliabilities at high temperatures simultaneously. Recently, porous rare earth (RE) silicates have been revealed to be excellent thermal insulators in harsh environments. These materials display attractive properties, including high porosity, moderately high compressive strength, low processing shrinkage (near-net-shaping), and very low thermal conductivity. The current critical challenge is to balance the excellent thermal insulation property (extremely high porosity) with their good mechanical properties, especially at high temperatures. Herein, we review the recent developments in processing techniques to achieve extremely high porosity and multiscale strengthening strategy, including solid solution strengthening and fiber reinforcement methods, for enhancing the mechanical properties of porous RE silicate ceramics. Highly porous RE silicates are highlighted as emerging high-temperature thermal insulators for extreme environments.

• Resources Recycling
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• v.27 no.3
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• pp.78-85
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• 2018

Effect of ball milling treatment on the hydrochloric acid leaching performance of black dross was investigated to recover alumina. Ball milling time and speed showed limited effect on the leaching behavior of the alumina in the mechanically dross. Under the optimum mechanical activation condition (for 1h at 700 rpm), the leaching of alumina in hydrochloric acid solution was significantly affected by leaching time and reaction temperature. MgO was completely dissolved in most of the leaching conditions, while a small amount of Ca, Fe, Si and Ti oxides was dissolved. Although 80% of alumina was dissolved, the dissolved minor components such as Ca, Fe, Mg, Si and Ti oxides should be separated to recover pure alumina solution.