Synergic effect of collector and frother on froth stability and flotation recovery: an industrial case.

Froth stability is known to play a significant role in determining mineral grade and recovery in a flotation operation, but although it is understood that the collection zone and the froth zone are deeply interconnected and that reagents, particularly collectors and frothers, cannot be selected without considering their synergistic effect, this concept is rarely applied in plant practice. Feed mineralogy also has an important role in how particles and reagents interact in flotation, which is sometimes overlooked by operators. A case study is presented of plant trials at the Prominent Hill Cu-Au mine in South Australia combined with batch laboratory flotation tests and froth stability measurements. The methodology was applied to the trial plant, which was experiencing high variability in froth stability in the roughers when the feed ore mineralogy was changing. It was hypothesised that chalcopyrite in the feed in combination with isobutyl-xanthate had a destabilising effect on the froth phase under the reagent scheme used. Froth stability was restored if a shorter-chain, less hydrophobic xanthate was employed. It is apparent that the hydrophobicity of adsorbed films at the solid/liquid/air interfaces has a critical role in enhancing or reducing froth stability. Unstable froth causes a reduction in Cu recovery in spite of a high collection-zone flotation rate. The case study suggests that collection zone and froth zone can rarely be optimised independently of each other. With the laboratory procedure adopted, a more suitable reagent scheme was determined to respond to changes in the feed mineralogy, avoiding fluctuations in plant performance due to unexpected froth instability. The methodology adopted could be applied to any mineral system and operation, assisting operators in determining factors affecting flotation performance and measures to mitigate the effect.
Froth stability is known to play a significant role in determining mineral grade and recovery in a flotation operation, but although it is understood that the collection zone and the froth zone are deeply interconnected and that reagents, particularly collectors and frothers, cannot be selected without considering their synergistic effect, this concept is rarely applied in plant practice. Feed mineralogy also has an important role in how particles and reagents interact in flotation, which is sometimes overlooked by operators. A case study is presented of plant trials at the Prominent Hill Cu-Au mine in South Australia combined with batch laboratory flotation tests and froth stability measurements. The methodology was applied to the trial plant, which was experiencing high variability in froth stability in the roughers when the feed ore mineralogy was changing. It was hypothesised that chalcopyrite in the feed in combination with isobutyl-xanthate had a destabilising effect on the froth phase under the reagent scheme used. Froth stability was restored if a shorter-chain, less hydrophobic xanthate was employed. It is apparent that the hydrophobicity of adsorbed films at the solid/liquid/air interfaces has a critical role in enhancing or reducing froth stability. Unstable froth causes a reduction in Cu recovery in spite of a high collection-zone flotation rate. The case study suggests that collection zone and froth zone can rarely be optimised independently of each other. With the laboratory procedure adopted, a more suitable reagent scheme was determined to respond to changes in the feed mineralogy, avoiding fluctuations in plant performance due to unexpected froth instability. The methodology adopted could be applied to any mineral system and operation, assisting operators in determining factors affecting flotation performance and measures to mitigate the effect.