Thermochemical study of calciothermy of Scandium compounds

Dr.-Ing. Alexander Arnold, M. Sc. Ksenija Milicevic, M. Sc. Frederic Brinkmann, Prof. Dr.-Ing. Dr. h.c. B. Friedrich

In this paper the results of thermochemical study on scandium production by calcium and calciumzinc alloys as reduction agents are presented. Possible system components, reaction mechanisms, concentration ratios of charge components, as well choice of temperature ranges for those multicomponent systems, are investigated by triangulation and tetraedration with help of software FactSage®. The conditions for maximum ensured scandium (Sc) yield from Sc2O3 and ScF3 compounds are listed to compare potentials of Sc production processes. Sc2O3 cannot be reduced directly by Calcium, but with Ca-Zn alloy. Minimum consumption of calcium and zinc as well maximum scandium content in product is reached by Ca-Zn alloy with 3 : 2 ratios. Next to pure calcium, it is possible to reduce ScF3 also by Ca-Zn alloy where scandium content in product decreases with increase of zinc proportion in reducing alloy.