Gold content in the ore is very low, in order to extract gold ore crushing and grinding needs and using pre-enrichment or beneficiation methods to separate gold from ore manipulation. Gold beneficiation using more re-election and flotation, gravity separation occupies a very important position in placer gold production, flotation is widely use rock gold mine beneficiation methods, currently about 80% of the country rock gold mine Using this method with gold, mineral processing technology and equipment have been greatly improved.
(A) crushing and grinding
According to the survey, South Africa, with gold plant to use more gold jaw crusher for primary crushing, the use of standard hpt hydraulic cone crusher broken, and crushing with short head type cone crushers and roller crushers. Medium and small with gold plant mostly used a closed-circuit crushing two large selected gold plant using a closed-circuit crushing three-stage process.
To improve mineral production capacity, potential mining equipment for crushing process was modified so that the grinding machine utilization factor increases, the main measures taken is the implementation of more crushing less grinding, reducing the size of ore into the mill.
Re-election in the rock gold mine used widely, more as an auxiliary craft, recovered in the grinding circuit coarse gold, to create favorable conditions for the flotation and cyanidation process, improve metallurgical performance, improve overall recovery of gold, to increase production and reduce the cost to play a positive role. South Africa and Ghana have more than 10 countries with gold plant using the re-election of this process, the average total recovery can be increased by 2% to 3%, good economic efficiency of enterprises, according to incomplete statistics, every year millions of dollars of profits available . The main equipment used are chute, shaker, jigger and short-cone cyclone and the like. From the point of view of the majority of gold mines, floating – heavy joint process (flotation tailings re-election) suitable for use in the future should vigorously promote the stage grinding stage sorting process, promote energy income, early harvest beneficiation principles.
According to the survey, about 80 percent of South African rock gold mine with gold flotation concentrate output multi sent to non-ferrous smelter processing. Because cyanide gold extraction of growing and businesses in order to improve economic efficiency, reduce concentrate transport losses in recent years, large changes in the product structure, and to take a more in-situ treatment (of course, due to the contradiction between the smelt and pricing and other issues, forcing the mine in situ discretion) to promote greater development of the flotation process, occupies an important position in gold production. Usually flotation and flotation two processes. In recent years, there is new progress in the transformation process and reagent addition system, the flotation recovery has improved markedly. According to South Africa, Ghana, more than 40 countries with gold mill, flotation process indicators survey results show that sulphide ore flotation recovery of 90%, a few up to 95% to 97%; oxide ore recovery was approximately 75%; the individual reaches 80 % to 85%. In recent years, the transformation of flotation process innovation and research a lot, the effect is obvious. Floating stage grinding process, heavy – floating joint process, is the main trend of the development of the flotation process.