Production of niobium powder by electronically mediated reaction (EMR) using calcium as a reductant

Abstract

Explored in this study is an electronically mediated reaction (EMR) route for the production of niobium powder using calcium as a reductant for niobium oxide (Nb₂O₅). Feed material, Nb₂O₅, and reductant calcium alloy containing aluminum and nickel were charged into electronically isolated locations in a molten salt (e.g. CaCl₂) at 1173 K. The current flow through an external path between the feed and reductant locations was monitored. A current approximately 0.4 A was measured during the reaction in the external circuit connecting cathode and anode location. Niobium powder with low aluminum and nickel content was obtained although liquid Ca–Al–Ni alloy was used as the reductant. This clearly demonstrates that niobium metal powder can be produced by an electronically mediated reaction (EMR), without direct physical contact between feed (Nb₂O₅) and reductant (calcium). Mechanism of calciothermic reduction of Nb₂O₅ in the molten salt is discussed using an isothermal chemical potential diagram.