In situ carbothermic reduction of a ferro-columbite concentrate in the recovery of Nb and Ta as metal matrix composite from tin smelting slag waste dump

The in situ carbothermic reduction of a ferro-columbite recovered from a tin smelting slag waste dump was investigated in the temperature range 1200–1400 °C using coarse and pulverised concentrate with collie coal and coke as reducing agents. Carbides of niobium (NbC) and tantalum (TaC) in an iron matrix were identified by X-ray diffraction (XRD) and electron probe microanalysis (EMPA) techniques, as the major constituents of the metal matrix composite (MMC) product of in situ carbothermic reaction. The extent of conversion, XB was found to vary depending on the particle size of the ferro-columbite concentrate, the type of reductant used, temperature and reaction time. The efficacy of collie coal as a reductant is due to its high reactivity and low ash content when compared with metallurgical coke.