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Materials 2019, 12(8), 1220; https://doi.org/10.3390/ma12081220

Hydrometallurgical Process for Tantalum Recovery from Epoxy-Coated Solid Electrolyte Tantalum Capacitors

1
Department of Resources Engineering, National Cheng Kung University, No.1 University Road, Tainan City 701, Taiwan
2
Department of Environmental Studies for Advanced Society, Graduate School of Environmental Studies, Tohoku University, Aoba-6-6 Aramaki, Aoba-ku, Sendai 980-8577, Miyagi, Japan
*
Authors to whom correspondence should be addressed.
Received: 29 March 2019 / Revised: 7 April 2019 / Accepted: 10 April 2019 / Published: 14 April 2019
(This article belongs to the Special Issue Metallurgy of Non-Ferrous, Rare and Precious Metals)
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Abstract

Tantalum is a critical metal that is widely used in electronic products. The demand for tantalum is increasing, but the supply is limited. As tantalum waste products have increased in Taiwan in recent years, the treatment of spent tantalum capacitors has become necessary and important. The recycling of tantalum from tantalum capacitors will not only decrease pollution from waste, but will also conserve tantalum resources. The tantalum content in epoxy-coated solid electrolyte tantalum capacitors (EcSETCs) is over 40 wt.%. Here, we designed a recycling process that includes pre-treatment, leaching, and solvent extraction to recover tantalum. In the pre-treatment process, epoxy resin and wires were removed. During hydrometallurgical process, pressure leaching by hydrofluoric acid was used to leach tantalum and manganese from solid electrolyte tantalum capacitors (SETCs). During our testing of this proposed process, the acid concentration, reaction time, temperature, and solid–liquid ratio were examined for leaching. After the leaching process, Alamine 336 was used to extract tantalum from the leaching solution. The pH value, extractant concentration, extraction time, and aqueous–organic ratio were investigated. Then, tantalum was stripped using HNO3, and the HNO3 concentration, stripping time, and organic–aqueous ratio were analyzed in detail. Under optimal conditions, the recovery efficiency of tantalum reached over 98%, and a final product of tantalum pentoxide with 99.9% purity was obtained after chemical precipitation and calcination. View Full-Text
Keywords: tantalum capacitors; recycling; hydrometallurgy; pressure leaching; solvent extraction tantalum capacitors; recycling; hydrometallurgy; pressure leaching; solvent extraction
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
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Chen, W.-S.; Ho, H.-J.; Lin, K.-Y. Hydrometallurgical Process for Tantalum Recovery from Epoxy-Coated Solid Electrolyte Tantalum Capacitors. Materials 2019, 12, 1220.

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