There are three main methods of gold extraction, namely, gravity separation, flotation process and cyanidation process, among which gravity separation is a relatively simple gold extraction method. This article takes the 300t/d gold ore dressing plant as an example to introduce the gold ore gravity separation process.
The processing plant is located in Guyana. It is open-pit mining. The raw ore is brittle and contains mud, and the lump ore is less than fine ore. The maximum size of the lump ore is less than 200mm. Xinhai carried out beneficiation test for the project after taking over the project. After the beneficiation test, the beneficiation process was determined as: a process flow of washing, dewatering and crushing-grinding process-gravity separation process.
The original ore contains cemented mud mass, some of which have a particle size larger than 100 mm. If this mud mass is not disintegrated, it will be excluded along with the waste rock during the screening process, resulting in the loss of gold. Therefore, Xinhai designed a process of washing, dewatering and crushing for it. After washing, the argillaceous powder minerals are de-slimed and dehydrated and then enter the crushing operation.
Before crushing, vibrating screen and trommel are often used as screening equipment, which have the characteristics of long service life and large processing capacity.
The washed and crushed products are sent to the ball mill for grinding. 70% to 75% of the qualified -200 mesh products enter the centrifuge for gravity separation.
The middling of shaking table returns to the grinding operation. The tailings of shaking table flow to the tailings pond by themselves, and the concentrate of shaking table is manually sent to the concentrating tables, and then the concentrate is directly smelted. The middling of re-separation is manually return to the grinding operation.
Project results: After the raw ore is ground, the grinding particle size is -200 mesh and 70-75%; after gravity separation, the yield of heavy sand is 0.086%, the gold grade is over 3000g/t, and the gold recovery rate is over 80%.
The 300tpd gold ore gravity separation is introduced above. From the process, we can see that the gold extraction method is very simple, which only use the physical difference between gold and gangue minerals to extract gold. To be specific, the technological process is simple; the investment of gravity separation machines is low and it is easy to operate. In addition, the process is environmentally friendly so the tailings can be directly discharged, which greatly reduces the civil construction investment of the entire processing plant.
However, this simple gold separation method is not suitable for all gold mines. It is mainly used in placer gold mines like seaside placer, riverside placer and alluvial placer.
