Technologies for Enhancing Gold Recovery in Flotation

In gold ore beneficiation, flotation typically involves flotation of gold into concentrates such as copper and lead, followed by extraction of gold from these concentrates. Consequently, flotation represents a relatively sound beneficiation method for ores where gold is contained within base metals. It enables the integrated utilisation of multiple metals; however, recovery rates remain comparatively low for oxidised ores, and the collection of coarse-grained gold presents significant challenges.

Subjective factors influencing the flotation process include grinding fineness, reagent regime, pulp concentration, agitation intensity, aeration volume, flotation duration, flotation circuit design, pulp index, and pulp temperature. When flotating sulphide ores containing gold, commonly employed collectors include xanthates, black oil, or mixtures thereof, alongside other novel reagents. Standard frothers include No. 2 or No. 11 oil, while common suppressants comprise lime, sodium sulphide, and potassium dichromate. Activators typically used include copper sulphate, lead nitrate, and lead acetate.

Single flotation is suitable for separating gold particles ranging from 0.5mm to 10μm. When feed particle size is smaller than this, specialised flotation methods are required. Carrier flotation employs mineral particles of suitable size as carriers, enabling fine gold particles to adhere to their surfaces and rise as gold concentrate. Common flocculants cause fine gold particles or gold-bearing minerals to agglomerate into larger aggregates. After removing fine gangue silt, coarse gangue particles are then floated off, constituting the flocculation-flotation process.

Methods employing oils to agglomerate fine mineral particles for flotation are termed oil agglomeration flotation or emulsion flotation. Separation flotation involves converting metallic minerals within ore into metals through high-temperature chemical reactions before flotation. However, this method is rarely employed for gold ores.

Currently, many vein gold mines in China utilise flotation as their primary beneficiation process, typically employing either priority flotation or mixed flotation methods. Significant advancements have been made in recent years regarding process flow technical upgrades and reagent addition protocols, resulting in markedly improved recovery rates for gold concentrates.

Naturally, flotation, like other methods, is not universally applicable and cannot yield favourable results for all gold-bearing ores. Consideration must be given to the ore's properties, and selecting the appropriate process flow requires comprehensive evaluation and testing to determine the final experimental scheme. To enhance separation efficiency, alongside continuous process refinement, considerable innovation, improvement, and research have been undertaken in reagent addition systems and mixed reagent usage. Concurrently, new advances have been made in achieving automated control of reagent dosing.