1. Graduate School of International Resources, Akita University, 1-1, Tegatagakuen machi, Akita-City 0108502, Akita, Japan
2. Sibanye-Stillwater Digital Mining Institute, University of the Witwatersrand, Johannesburg 1864, South Africa
3. Faculty of Engineering, Division of Sustainable Resources, Hokkaido University, 13 jyounishi 8, Kita-ku, Sapporo-City 0608628, Hokkaido, Japan