Gold ore gravity separation process is a physical separation method based on the difference in mineral density. It is widely used in the separation of placer gold and vein gold due to its low cost and strong environmental protection. With the development of low-grade and fine-grained gold resources, gravity separation technology has become a key link in improving resource recovery rate by combining with flotation, cyanidation and other processes.

1. Gravity separation process principle and core equipment

The gravity separation process separates high-density gold particles from gangue through water flow, gravity and centrifugal force. The core equipment includes:

Jig: Suitable for rapid separation of coarse gold (0.019-3mm), using pulsed water flow to achieve mineral stratification and enrichment.

‌Shaking table: Suitable for fine separation, through the reciprocating motion of the inclined bed surface, minerals of different densities are formed into a banded distribution, and the recovery rate can reach more than 90%.

‌Spiral chute: Processes fine-grained materials (0.02-0.3mm), and separation is achieved by centrifugal force and water flow flushing, mostly used for tailings reprocessing.

‌Centrifugal concentrator‌: For fine gold (<0.02mm), the centrifugal force generated by high-speed rotation is used to enhance the sorting effect, which is especially suitable for low-grade tailings recovery.

2. Typical process flow

Gold ore re-selection usually includes the following steps:

‌Crushing and grinding‌: Use jaw crusher and cone crusher for multi-stage crushing, and ball mill to grind the ore to less than 0.074mm to release the encapsulated gold.

‌Grading and screening‌: Use spiral classifier or high-frequency screen to achieve particle size control to ensure the best processing effect of re-selection equipment.

‌Gravity enrichment‌: Coarse gold is pre-selected by jig, medium and fine gold is sorted by shaking table or chute, and tailings are recovered by centrifuge for secondary recovery.

‌Concentrate purification‌: Gravity concentrate is further purified by amalgamation, cyanidation or smelting to produce high-grade gold ingots.

3. Technical advantages and application scenarios

‌Gold placer processing‌: Gravity separation can directly recover free gold from placer, with a simple process and low investment cost. For example, the Heilongjiang gold placer adopts a jigging-shaking table combined process with a recovery rate of over 85%.

‌Vein gold ore auxiliary separation‌: In rock gold concentrators, gravity separation is used to recover coarse gold in the grinding circuit in advance to reduce over-grinding losses. After a gold mine in Shandong introduced a shaking table, the total recovery rate increased by 2%-3%, with an annual profit of several million yuan.

‌Tailing resource utilization‌: Centrifuges and other equipment can process flotation tailings and recover fine gold, reducing the tailings grade from 0.3g/t to below 0.1g/t, and increasing resource utilization by 30%.

4. Development trend

‌High efficiency and energy saving‌: Equipment is developing towards large-scale and low energy consumption, such as a new centrifuge with a 40% reduction in energy consumption and a 50% increase in processing capacity.

‌Intelligent control‌: Real-time adjustment of sorting parameters through sensors and automation systems, such as intelligent optimization of shaker stroke and water flow rate, improves sorting efficiency by 15%-20%‌. ‌Process synergy‌: Gravity separation is deeply coupled with flotation, bioleaching and other processes to form a full-process system of "gravity separation pre-enrichment-flotation purification-tailings cyanidation", with a comprehensive recovery rate of more than 92%.

The gold ore gravity separation process continues to play an important role in the efficient development of gold resources due to its wide adaptability and environmental friendliness. In the future, with the deepening of the concept of intelligence and green mining, this technology will promote the gold beneficiation industry to develop in a more efficient and sustainable direction‌.