Effect of Gas Dispersion Properties and Bias in Scheelite Column Flotation

In this study, column flotation was used to recover a high-grade concentrate from low-grade WO3 ore. Gas dispersion properties, such as superficial gas velocity, gas holdup, bubble size, bubble surface area flux, carrying rate, and bias, were investigated in two phases (gas-liquid) and three phases (gas-liquid-solid) in the column, and their effects on the grade and recovery of WO3. It was confirmed that the gas velocity significantly affected these factors, with the gas holdup, bubble size, bubble surface area flux, and carrying rate tending to increase as the gas velocity increased. The bias increased with an increase in the wash water velocity. The results showed that the grade and recovery of WO3 could be controlled within a specific range of operating conditions of bias (0.27-0.48 cm/s) and carrying rate (10.53-18.83 g/min/cm2). Correlation plots of grade/recovery versus bias and carrying rate revealed that the optimal separation achievable for a given WO3 concentrate in a flotation column was a 72.16% grade with a 78.3% recovery, satisfying the metallurgical requirement of more than 50% for WO3.