Effect of entrainment in bubble load measurement on froth recovery estimation at industrial scale

• Bubble load measurements were carried out in industrial flotation cells.
• A decrease in the bubble load grade (−45 μm) was observed due to entrainment.
• The estimated entrainment in the bubble load device ranged from 7–8%.
• The froth recovery estimation showed a relative error lower than 0.3%.

Froth recovery was calculated in a 130 m3 mechanical cell of a rougher flotation circuit. This was done by bubble load determinations along with mass balance surveys. Valuable grade in the bubble load decreased in the −38 μm due to fine particles entrained to the chamber of the device. The effect of fine particle entrainment on froth recovery was evaluated. A comparison between results from the raw bubble load data (assuming all particles were transported by true flotation) with those from corrected bubble load information (subtracting fine particle entrainment) was carried out. Entrainment occurred due to hydraulic transport in the bubble rear, which corresponds to the worst case scenario for froth recovery estimation. Results showed that the relative error was less than 0.3%, which allowed validation of the bubble load measurement as an effective methodology for froth recovery estimation at industrial scale.

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