The froth stability column: linking froth stability and flotation performance

Froth structure and stability are known to play important roles in determining mineral flotation recovery and selectivity. However, measuring froth stability quantitatively, both at laboratory and industrial scales remains a significant challenge. A quantitative dynamic stability measure has previously been evaluated at laboratory scale. The technique is based on the Bikerman foam test and uses a non-overflowing froth column to quantify froth stability. At laboratory scale the froth stability measured in this way agreed very closely with other methods, and could be related to flotation performance. In this paper, the froth stability column is tested at Northparkes, Australia. The dynamic froth stability Sigma and froth stability factor beta were measured under different operating conditions, and compared with the fraction of air overflowing the cell, alpha, which was measured using image analysis. The froth stability column results gave the same trends as image analysis. In particular the froth stability factor was found to be linearly related to the actual fraction of air overflowing the cell. The metallurgical results clearly indicated that changes in air rate, froth depth and frother concentration result in variation in flotation performance that can be attributed to changes in froth stability. The results showed that high froth stability conditions occur at lower air flowrates, and result in improved flotation performance. It is found that the froth stability column is an accurate and cost-effective method for quantifying froth stability, and for indicating changes in flotation performance. (C) 2004 Elsevier Ltd. All rights reserved.