1. 1) Agency for Natural Resources and Energy, Ministry of Economy, Trade and Industry: Non-Ferrous Metals Supply and Demand Statistics Survey 2018, (2019), https://www.enecho.meti.go.jp/statistics/coal_and_minerals/cm002/pdf/2018/h30nenpou.pdf, (in Japanese), (accessed 2020-3-30).
2. 2) H. Sugimoto, H. Takizawa and H. Ueda: J. MMIJ, 123(2007), 723 (in Japanese).
3. 3) T. Yoshida: J. MMIJ, 113(1997), 967 (in Japanese).
4. 4) S. Itoh, A. Tsubone, K. Matsubae-Yokoyama, K. Nakajima and T. Nagasaka: ISIJ Int., 48(2008), 1339.
5. 5) K. Nakajima, K. Matsubae-Yokoyama, S. Nakamura, S. Itoh and T. Nagasaka: ISIJ Int., 48(2008), 1478.