Continuous Extraction of Nickel from Superalloy Scraps Using Zinc Circulation
A novel technique for the continuous extraction of nickel (Ni) from Ni-based superalloy scraps using molten zinc (Zn) has been proposed, and its feasibility was experimentally demonstrated. The newly developed approach allows for extraction of Ni metal directly from superalloy scraps with simultaneous separation of the Zn from the resulting Zn-Ni alloy. The optimal conditions for the extraction of Ni and separation of valuable elements such as rhenium (Re), tantalum (Ta), and tungsten (W) were determined by varying major process parameters including the reaction time and configuration of the reaction chamber. The proposed method has been successfully utilized for the production of the superalloy containing 62.8 mass pct of Ni and 15.5 mass pct of refractory metals (Re, W, and Ta). Under certain conditions, 41 pct of the Ni contained in the superalloy could be extracted at 1173 K (900 °C) over 48 hours, producing an alloy containing 84.0 mass pct of Ni and 0.2 mass pct of the refractory metals.
KeywordsTurbine Blade Reaction Chamber Refractory Metal Quartz Crucible Crucible Bottom
The authors are grateful to Emeritus Professor Yoshiaki Umetsu from Tohoku University as well as to Professor Shunsuke Yagi, Dr. Yu-ki Taninouchi, and Dr. Akihiro Yoshimura from The University of Tokyo, for their generous support and valuable discussions. This research study was supported by a Grant-in-Aid for Scientific Research (S) (Grant Number 26220910). Ryohei Yagi is grateful for the financial support provided by the Doctoral Student Special Incentives Program (SEUT-RA) of the University of Tokyo, Japan.
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