Placer gold beneficiation is to use gravity separation equipment by means of the different gravity of gold particles and gangue minerals first to recover gold from raw ore through gravity separation process, and then to separate gold and various heavy sand minerals with a single or combined processes of gravity separation method, flotation method, magnetic separation method and electrostatic separation method, so as to achieve the purpose of comprehensive recovery. It mainly includes the following operational processes, and placer gold beneficiation equipment.
Ore washing operation is an important process before the placer gold sorting operation. Its main purpose is to separate the gravel, sand and granular soil, and wash the fine mud adhering to the gravel and the gold ore mixed in it. Generally, placer gold ore often contains more weathered clay, and gold ore sand is wrapped in it to form cemented agglomerate or mud body together. If it is not broken up in advance, the cemented agglomerates or mud will be discharged together with the waste rock during the screening process, thereby reducing the recovery rate of placer gold ore and causing the loss of gold.
The placer gold beneficiation equipment used in the ore washing operation mainly includes: first wash with water and then through mechanical agitation such as plane vibrating screen, cylindrical washing machine, cylindrical screen, etc. to dissolve the ore wrapped in cement block or slurry to separate the gravel, sand and clay, and wash away the clay and gold particles adhering to the gravel. This operation can improve the separation ability of the placer gold ore and is beneficial to improve the recovery rate of the placer gold ore.
Under normal circumstances, the main purpose of the screening operation is to screen the placer gold after washing, and to screen out large pieces of gravel without gold, so as to improve the gold selection efficiency. Generally, 20-40% of the waste rock (gravel, pebbles) can be removed by the screening operation.
In the screening operation of placer gold mines, water screens are often used, and the ore mud on the screen is washed with water, so as to improve the screening efficiency of placer gold mines. Usually, the size of the screen hole of the gold placer screening equipment needs to be determined according to the particle size composition parameters of the gold in the raw ore sand. At present, the common screen hole is generally 10-20mm. When a fixed chute is used for roughing operation, the screen hole can be larger, but the upper limit cannot exceed 60mm. Fixed concentrators often use vibrating screens or grid screens as placer gold screening equipment, and cylindrical screens are often used as gold dredgers.
The gravity separation process is mainly used for the separation of placer gold. There are mainly two reasons. The first reason is that the specific gravity of placer gold is large and the particle size- generally 0.074~2mm- is coarse. And the second is because the gravity separation process is economical and simple. Gravity separation is a key operation in the separation stage of placer gold. Gravity separation equipment such as jigs, shaking tables, and chutes are often used to discharge most of the waste rock to obtain coarse gold concentrate.
According to different types of placer gold ore, the concentration operation can adopt gravity separation process, magnetic separation process, flotation process, electric separation process or combined process to separate gold and various heavy minerals from each other, so as to further improve the grade of gold. Concentration operation is also one of the indispensable processes in the process of beneficiation of gold placer ore. Special attention should be paid to the selection of concentration operation technology and equipment to avoid the loss of gold and fully improve the quality of gold and other heavy sand minerals, thus achieve the purpose of comprehensive recycling.
Usually, we judge the need for dewatering according to the process used in the concentration operation. Gravity separation, magnetic separation, and flotation processes can be carried out under wet conditions, while electrical separation processes require dry conditions. Generally, the dewatering operation of placer gold mine adopts concentration and filtration process.
In actual production, the beneficiation process and beneficiation equipment of placer gold ore need to be determined in combination with factors such as ore properties, dressing plant conditions, investment budget and other factors. Therefore, it is recommended to choose an equipment manufacturer with beneficiation qualifications, and to take comprehensive considerations to customize your scientific and reasonable placer gold beneficiation process and equipment.
