| A laboratory scale plasma spout-fluid bed has been developed to calcine concentrated vanadium ore to extract vanadium in the form of sodium metavanadate. A 20-kW d.c. plasma torch was used with argon and nitrogen as the plasma gases. Air, the main fluidizing gas, permitted the fluidization of the vanadium concentrate within the bed and provided the oxygen for the roasting reaction. In addition, air injected tangentially into the spout region lowered the plasma gas temperatures to within the required roasting temperatures.;The bed stability and degree of vanadium recovery were analyzed as a function of bed temperature, time, and concentrate-to-salt ratio. It was shown that heating and reaction in the reactor occur primarily as the particles pass through the plasma spout. If spout temperatures are too high, melting and agglomeration of the particles occurs, leading to defluidization of the bed.;Conversion during batch operation, with sodium carbonate as the salt, was rather unsuccessful due to elutriation of the salt during heat-up. The highest conversions were observed in the fused and agglomerated particles of the bed. Simulated continuous operation of the bed however resulted in significantly higher conversion rates. |
