Preparation for flotation of gold in placer gold beneficiation
About 80% of my country's rock gold mines use flotation technology, and most of the produced concentrates are sent to non-ferrous smelters for processing. Due to the increasing development of gold extraction by the cyanidation method and enterprises in order to improve economic benefits and reduce the loss of concentrate transportation, the product structure has undergone major changes in recent years, and more on-site treatment has been adopted (of course, due to the contradiction and Pricing and other issues force the mine to handle it on-site) to promote the development of the flotation process, which occupies a fairly important position in gold production. There are usually two processes, priority flotation and mixed flotation.
In recent years, new progress has been made in technological process transformation and reagent addition system, and the flotation recovery rate has also been significantly improved. According to more than 40 gold concentrators across the country, the flotation process index survey results show that the flotation recovery rate of sulfide ore is 90%, with a few as high as 95%-97%; the recovery rate of oxide ore is about 75%; and the individual reaches 80%～ 85%. In recent years, there have been many innovations in the flotation process and scientific research results, with obvious effects. Stage grinding and flotation process, heavy-flotation combined process, etc., are the main trends in the development of flotation technology in my country.
Extended reading: The more common sand gold mine gravity separation process and equipment
Preparatory work to be carried out before the sorting of placer gold mine:
Placer gold mines usually do not require crushing and grinding, which can save a lot of equipment investment and operating costs compared with vein gold mines. The ore preparation work before gold selection is mainly screening, grading and washing. In order to divide the rock into single particles and completely separate the valuable mineral particles, placer gold mines also need to have fragmentation operations, but generally do not require a separate process. If the placer gold deposit is mined by hydraulic mining, the rock fragmentation operation is basically completed in the mining process. When other mining methods are used, the decomposition and classification of rocks and the washing operations are often carried out in the same equipment (for example, a flat screen or a rotating drum).
The ratio of the maximum particle size of the gangue of the placer gold mine to the minimum particle size of the placer gold can reach several thousand times, and the large gravel usually contains no gold. Through the classification operation, the metal-free boulders and gravels can be separated, thereby greatly reducing the volume of the selected materials.
The disintegration operation requires a certain amount of power. The power consumption per unit weight of material is the standard for the intensity of a certain equipment disintegration operation. The more viscous the material being processed, the more power required. Placer gold mines can be divided into easy-to-wash (gravel-pebbles-containing) ore sands, medium-washable (a small amount of clay) ore sands, and difficult-to-wash argillaceous sands (containing a small amount of clay) according to the difficulty of material disintegration and washing. Large amounts of clay) ores.
Production practice shows that in the process of placer gold beneficiation, washing and grading is a very critical link. The ore washing is not clean, the metal loss is serious, and the mud mass destroys the sorting operation, which reduces the recovery rate and gold output. The classification is not good, the coarse and fine particles are mixed, and the sorting effect is not good. Based on the systematic analysis of the particle size composition of the ore sand and the distribution rate of gold, a feasible ore washing and grading plan should be formulated in combination with the specific conditions of each mine.