Gold Ore Gravity Separation Process: From Principle to Practice

Gravity separation serves as a crucial method in gold ore beneficiation, operating on the core principle of exploiting the density disparity between gold ore and gangue to achieve separation under conditions of mineral liberation. Gold ores are primarily categorised as placer ores and vein ores. Placer ores contain gold concentrations of 0.3–2 g/m³, with gold predominantly occurring as free native gold. Their pronounced density disparity makes them ideal candidates for gravity separation. Vein ores typically contain gold concentrations of 0.5–5 g/t. Gravity separation alone is rarely sufficient for vein ores, necessitating integration with other processing methods. Placer gravity separation commonly employs three methods: jigging, shaking tables, and sluice boxes.

Jigging for Efficient Separation of Coarse-Grained Gold Ore

Jigging employs vertically pulsating water currents to separate ore particles, with the jig serving as the core equipment. Mineral grains stratify according to specific gravity within the vertically variable-velocity medium flow, with lighter minerals rising to the top and heavier minerals settling below. They are then discharged separately through mechanical action and water flow. This method is suitable for coarse-grained minerals ranging from 50mm to 0.074mm in size. In placer gold processing, where the specific gravity difference between minerals is ≥0.5 and the ore exhibits single-grain liberation, the lower size limit can extend to 0.04mm. This process is simple to operate and offers high throughput, making it widely used for rough separation in gold mining.

Shaking Table Gold Recovery: Precise Separation of Fine-Grained Gold Ore

Shaking table gold recovery employs reciprocating bed motion and water flushing to separate fine-grained minerals within a horizontal medium flow. The equipment utilises a shaking table. Slurry is uniformly distributed across an inclined bed surface. The combined action of bed motion and water flow causes mineral particles to stratify vertically by density and separate horizontally by grain size. Heavy minerals concentrate at the bed base, while light minerals are carried away by the water flow. Classified by ore particle size: coarse sand beds (2.0–0.5 mm), fine sand beds (0.5–0.074 mm), and mud beds (0.074–0.037 mm). Feed particle size range: 3 mm to 0.019 mm. Offers stable gold recovery, distinct mineral zones, high concentrate ratios, and straightforward management.

Trough Gold Recovery for Fine-Grained Gold Ore Processing

Trough gold recovery utilises the differential movement of ore particles within an inclined fluidised medium for separation, with the primary equipment being spiral troughs. Through the combined action of water flow, mineral gravity, and friction against the chute base, particles settle according to specific gravity. Lighter particles are carried away while heavier ones remain. This method is particularly suited to fine-grained gold ores with low clay content, processing sizes from 2 mm to 0.03 mm. It features a simple process structure, high throughput, and low overall costs.

Gravity separation demonstrates outstanding recovery efficiency for coarse gold in placer deposits. For vein gold deposits, it is often combined with flotation and cyanidation processes (e.g., gravity-flotation combined, gravity separation-cyanidation combined). In practical applications, mineral testing must first be conducted to analyse ore properties, followed by process optimisation and selection of equipment and process combinations to achieve optimal separation results.