超臨界条件下でのFeWO₄およびMgWO₄と2M塩化物水溶液間における2価金属イオンの同時分配実験

抄録

The distribution of Mg²⁺, Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Zn²⁺ and Ca²⁺ between FeWO₄ (ferberite), MgWO₄ (huanzalaite) and 2M aqueous chloride solutions was experimentally investigated under supercritical hydrothermal conditions of 500 to 800°C, 1 kb and 600°C, 0.5 to 2.0 kb.
The experimental results revealed that the cations were taken into solid phases (ferberite and huanzalaite) selectively in the following order:
Ni²⁺>Mg²⁺≥Fe²⁺>Mn²⁺＝Co²⁺>Zn²⁺>Ca²⁺.
The obtained partition coefficient - ion radius (PC-IR) curves mark a peak around Fe²⁺. However partition coefficients of Zn²⁺, Ni²⁺ and Mg²⁺ deviate from obtained PC-IR curves. Zn²⁺ shows a negative anomaly the same as other minerals with 6- or 8-fold sites. On the other hand, Ni²⁺ represents a positive anomaly. As for Mg²⁺, its partition coefficients locate on the estimated PC-IR curves at 500°C. However Mg²⁺ shows a positive anomaly with increasing temperature