The gold content in the ore is very low, in order to extract gold ore crushing and grinding necessary and the use of pre-enrichment, or beneficiation method of separating gold from ore manipulation. The most used in gold beneficiation is re-election and flotation. The re-election method plays an important role in the production of gold. Flotation method is a widely used ore dressing method in rock gold mines. At present, about 80% of China's rock gold mines With this method of gold selection, the level of mineral processing technology and equipment has been greatly improved.
(1) crushing and grinding
According to the survey, China's gold-removing plants mostly use a jaw crusher for coarse crushing, which is crushed by a standard cone crusher, while the fine crusher uses a short-head cone crusher and a pair of crusher. Most of the small and medium-sized gold-removing plants use two-stage closed-circuit crushing ore, and the large-scale gold-removing plant adopts a three-stage and one closed-circuit crushing process.
In order to improve the mineral processing capacity, tap the potential of the equipment , and transform the crushing process, the utilization factor of the grinding machine is improved. The main measures taken are to implement multiple crushing and grinding, and reduce the grain size of the grinding ore.
Re-election is widely used in rock gold mines, mostly as an auxiliary process, recovering coarse gold in the grinding circuit, creating favorable conditions for flotation and cyanidation process, improving beneficiation index, increasing total gold recovery rate, and increasing production. And played a positive role in reducing costs.
About 10 gold-removing plants in Shandong Province have adopted the process of re-election. The average total recovery rate can be increased by 2% to 3%. The economic benefits of enterprises are good. According to incomplete statistics, millions of yuan of profits can be obtained every year. Henan, Hunan, Inner Mongolia and other provinces (regions) have also achieved good results. The main equipment used is chute, shaker, jig and short cone cyclone. From the perspective of most gold mines in China, the floating-heavy combined process (re-election for flotation tailings) is suitable for adoption. In the future, the selection process of the stage grinding stage should be vigorously promoted, and the principle of mineral processing for harvesting and early harvest should be promoted.
According to the survey, about 80% of China's rock gold mines use the flotation method to select gold, and the produced concentrates are sent to the non-ferrous smelters for treatment. Due to the increasing development of gold by cyanidation and the improvement of economic benefits and reduction of concentrate transportation losses, the product structure has undergone major changes in recent years, and more local treatment has been adopted (of course, due to the contradiction between pricing and smelting Such problems, forcing the mine to deal with it on its own, have led to a major development in the flotation process and occupy a considerable position in gold production. There are usually two processes of preferential flotation and mixed flotation.
In recent years, there have been new progress in process modification and pharmaceutical addition systems, and the flotation recovery rate has also increased significantly. According to the survey of flotation process indicators in more than 40 gold selection plants across the country, the recovery rate of sulphide ore flotation is 90%, a few are as high as 95% to 97%; the recovery rate of oxidized ore is about 75%; 85%. In recent years, there have been many innovations and research results in the flotation process, and the results have been obvious. Stage grinding process, heavy-floating combined process, etc., is the main trend of China's flotation process development.
For example, the Xiangxi Gold Mine adopts the heavy-floating combined process to select the stage grinding stage and obtain better indicators. The recovery rate is increased by more than 6%; Jiaojia Gold Mine, Wulong Gold Mine, Wenyu Gold Mine, Dongpu Gold Mine, etc. Get a certain effect. Another example is the Xincheng Gold Mine. The original process is direct flotation of the ore. Due to the high mud content (the ore itself is high in mud, and the filling strength of the tailings is not enough, the mud sand is brought in), the ore dressing index is continuously decreased. After the test, the sludge sand separation process was adopted, the recovery rate was increased from 93.05% to 95.01%, and the concentrate grade 135g/t was increased to 140g/t, which stabilized the production.
Due to the decline of the grade of raw ore in Jinchangyu gold mine, the flotation index is reduced. The joint flotation process with Shenyang Gold College and other units has adopted the branch flotation process to improve the flotation index and concentrate grade.
This scientific research result (in January 1988, the Gold Corporation passed the technical appraisal), which has gained new enlightenment for the flotation process. Of course, the flotation method is not omnipotent like other methods. It is impossible to be effective for all gold-bearing ores. It is mainly necessary to consider the nature of the ore. When selecting the process, it is necessary to conduct various demonstrations and tests.
In recent years, in order to improve the sorting effect, while the process is continuously improved, many improvements and researches have been made on the pharmaceutical additive system and mixed drug use, and new progress has been made in the automatic control of dosing.
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