Precision Processing for Precious Recovery

Gold flotation efficiency depends on several interrelated variables, starting with particle size—typically ground to below 75 µm to liberate gold from the host matrix. Proper pulp pH, generally maintained between 6 and 9, ensures optimal reagent activity and mineral selectivity. The type and dosage of reagents—collectors like xanthates, frothers such as MIBC or pine oil, and pH modifiers like lime—play a critical role in ensuring gold particles attach to air bubbles while unwanted gangue is suppressed.

Additional factors include pulp density, which influences particle–bubble collision rates and froth stability; an ideal range lies between 25–40% solids by weight. Temperature also affects reagent kinetics and bubble formation, with moderate warmth often improving efficiency. Finally, flotation time must be carefully controlled—too short results in poor recovery, too long risks reduced concentrate grade. Balancing all these variables is crucial to maximize recovery, improve product quality, and reduce reagent costs in gold flotation operations.

Flotation is generally not the preferred method for recovering coarse, free-milling gold, which is best captured using gravity-based methods such as shaking tables, centrifugal concentrators, or jigs. These techniques effectively separate gold particles larger than 100 µm due to their high density. However, when free gold is finely disseminated—typically under 50 µm—flotation becomes a valuable recovery technique. By using suitable collectors and frothers, fine gold particles can be floated, especially when associated with sulfides or embedded in complex matrices. In such cases, flotation followed by cyanidation of the concentrate can improve overall gold recovery. While not ideal for all free gold, flotation plays an important role in processing fine or refractory gold ores that cannot be efficiently treated by gravity alone.