Gold Ore Beneficiation: Gravity Separation, Flotation, and Combined Processes

Gold ore beneficiation is a core process for achieving efficient utilisation of gold resources, and the selection of beneficiation processes must be precisely determined based on the properties of the ore (such as the occurrence state of gold, mineral composition, and grain size distribution). Currently, gravity separation, flotation, and combined processes are the primary technical approaches for gold ore beneficiation, each playing a critical role in different scenarios.

I. Gravity Separation: Physical Separation Based on Density Differences

Gravity separation is a physical method that utilises the density difference between gold minerals and gangue minerals (gold has a density of 19.3 g/cm³, significantly higher than quartz, feldspar, and other gangue minerals) to achieve separation. Its core principle is to leverage the differing settling speeds of various minerals in a gravitational field to concentrate gold particles. This process does not require chemical reagents, making it environmentally friendly. It is suitable for placer gold deposits and coarse-grained rock gold deposits, particularly for processing ore with gold particle sizes greater than 0.074 mm.

2. Flotation Method: Efficient Enrichment Based on Surface Properties

The flotation method exploits the natural flotation differences between gold minerals and gold-bearing sulphides (such as pyrite and arsenopyrite) to achieve separation through reagent control. Gold is often present as fine particles encapsulated within sulphides, and flotation can concentrate gold in the sulphide concentrate. This process is suitable for most rock gold deposits and associated gold deposits, particularly effective for ‘poor, fine, and complex’ ore.

3. Combined Process: A Comprehensive Solution with Synergistic Optimization

For ores with uneven grain size distribution, a combined process of ‘gravity separation to recover coarse-grained gold + flotation to recover fine-grained gold’ is adopted. For example, coarse-grained gold is first recovered using a jig, and the tailings are ground and then floated, which can increase the total recovery rate by 10% to 15%. This process reduces over-grinding losses through staged recovery and is particularly suitable for quartz vein-type gold deposits.