Development of efficient recovery of cobalt from aqueous solution by utilizing gel precipitation of cobalt thiocyanate complex.

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K18271
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Metal making/Resorce production engineering
• Research Institution: The University of Tokyo
• Principal Investigator: Shirayama Sakae 東京大学, 大学院工学系研究科(工学部), 助教 (70758416)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: コバルト / リサイクル / ポリエチレングリコール / チオシアン酸錯体 / ゲル / 溶媒抽出 / 電解

Outline of Final Research Achievements

Recycling process of cobalt (Co) was quantitatively evaluated to confirm its feasibility. In the process, potassium thiocyanate (KSCN) and polyethylene glycol (PEG) were added to aqueous solution containing Co, and Co was recovered in a gel-like compound. The process was divided into three steps; (1) Gel-like compound precipitation, (2) gel-like compound re-dissolution and solvent extraction of Co, and (3) Co electrolysis.
In step (1), conditions for an efficient precipitation was clarified. The reaction enthalpy was also calculated on the assumption of a formation reaction formula. In step (2), the influence of the coexistence of the gelling agent on the solvent extraction of Co was investigated. The extraction conditions to achieve the Co/Ni ratio required in the subsequent process was revealed. Then, the concentrations of impurities introduced to the electrolysis process were clarified. In step (3), the influence of impurities on the electrodeposition of Co was investigated.

Free Research Field

非鉄金属製錬

Academic Significance and Societal Importance of the Research Achievements

リチウムイオン電池(LIB)のスクラップから有価元素であるコバルト(Co)を効率よく回収することを目的に提案したプロセスについて、各工程における濃度条件などを定量化し、具体的なプロセス条件を決定するための指針を得ることができた。ゲル状化合物の析出反応に関する定量化と考察は学術的に新しいデータである。さらに、ゲル状化合物を工業的に利用する段階で、ゲル化剤が水溶液中に混入することによる溶媒抽出や電解への影響が明らかになった。従来、製錬の分野では利用されていなかったゲル状化合物を有価元素の回収媒体として考え、積極的に利用できる可能性を示したほか、プロセス設計に必要な知見を得ることができた。