Treatment of columbite and tantalite ores

摘要

Niobium and tantalum values are extracted from ores e.g columbite and tantalite by thoroughly mixing the ore with sodium or potassium hydroxide and roasting to form a soft friable mass from which the metal values are extracted by known methods e.g. hydrochloric acid for niobium and fractional crystallization from hydrofluoric acid for tantalum. The amount of alkali added is such that there is no separate molten alkali phase when the roasting is terminated. The roasting may be carried out at 600-800 DEG C. Before mixing with alkali the ores are preferably ground to a particle size finer than 200 mesh B.S.S. Tantalite ores of high manganese content are preferably roasted in an atmosphere of nitrogen.