The gold content in the ore is extremely low. In order to extract gold, it is necessary to crush and grind the ore, and enrich it in advance or separate gold from the ore through mineral processing. Gravity separation and flotation are widely used in gold mineral processing, and gravity separation plays a very important role in placer gold production. Flotation is a widely used mineral processing method in rock gold mines. At present, about 80% of rock gold mines in China use this method to select gold, and the level of mineral processing technology and equipment has been greatly improved. According to the investigation, jaw crushers are mostly used for coarse crushing, standard cone crushers are used for medium crushing, and short-headed cone crushers and roller crushers are used for fine crushing. Most small and medium-sized gold concentrator adopts two-stage and one-closed circuit ore crushing process, while large gold concentrator adopts three-stage and one-closed circuit ore crushing process. In order to improve the mineral processing capacity and tap the potential of equipment, the ore crushing process was reformed, and the utilization coefficient of the mill was improved. The main measures taken are more crushing and less grinding to reduce the grinding particle size. 2) Gravity separation is widely used in rock gold mines, mostly as an auxiliary process for recovering coarse-grained gold in grinding circuit, which creates favorable conditions for flotation and cyanidation, improves mineral processing indexes, improves the total recovery rate of gold, and has a positive effect on increasing production and reducing costs. More than 0/0 gold concentrator in Shandong province have adopted gravity separation technology, and the average total recovery rate can be increased by 2% ~ 3%, which has good economic benefits. According to incomplete statistics, millions of yuan can be earned every year. Henan, Hunan, Inner Mongolia and other provinces (regions) have also achieved good results, and the main equipment used is chute, vibrating screen, jig and short cone cyclone. From the point of view of most gold mines in China, the combined flotation-gravity separation process (gravity separation of flotation tailings) is suitable, and the stage grinding and stage separation process should be vigorously promoted in the future, and the principle of early harvest should be advocated. 3) Flotation According to the survey, about 80% of rock gold mines in China use flotation to select gold, and most of the concentrates produced are sent to non-ferrous smelters for treatment. Due to the increasing development of cyanide gold extraction and the efforts of enterprises to improve economic benefits and reduce concentrate transportation losses, the product structure has changed greatly in recent years, and more on-site treatment has been adopted (of course, due to the contradiction between dressing and metallurgy and pricing problems, mines are forced to treat themselves on the spot), which has promoted the great development of flotation technology and occupied a very important position in gold production. There are usually two processes: preferential 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 the investigation results of flotation process indexes of more than 40 gold concentrator in China, the flotation recovery rate of sulfide ore is 90%, and a few of them are as high as 95% ~ 97%. The recovery rate of oxidized ore is about 75%; Individual reached 80% ~ 85%. In recent years, there are many innovations and scientific research achievements in flotation process, and the effect is obvious. At present, stage grinding-flotation process and gravity flotation combined process are the main trends of flotation technology development in China. For example, Xiangxi Gold Mine adopts the combined process of gravity and flotation, carries out stage grinding and stage separation, and obtains good indexes, and the recovery rate is increased by more than 6%; Jiaojia Gold Mine, Wulong Gold Mine, Wenyu Gold Mine and Dongchuang Gold Mine have also made certain achievements. Another example is Xincheng Gold Mine. The original process is direct flotation of raw ore. Due to the high mud content (high mud content of ore itself, insufficient cemented filling strength of mining tailings, which brings some mud and sand), the mineral processing index is declining continuously. After investigation and experiment, the recovery rate was increased from 93.05% to 95.0 1% and the concentrate grade was increased from 135g/t to 140g/t by using the mud-sand separation process, which stabilized the production. Because the grade of raw ore in Jinchangyu Gold Mine is decreasing year by year, the flotation index is decreasing. Through the experimental study with Shenyang Gold Research Institute and other units, the branch flotation process was adopted to improve the flotation index and concentrate grade. This scientific research achievement (passed the technical appraisal in June 1988 and June 1) has gained new enlightenment for the transformation of flotation process. Of course, flotation, like other methods, is not omnipotent and cannot be effective for all gold-bearing ores. When selecting the technological process, we should mainly consider the properties of ore and carry out various demonstrations and tests. In recent years, in order to improve the separation effect, many improvements and studies have been made on the dosing system and mixed medication while the process has been continuously improved, and the automatic control of dosing has also made new progress. 4) Chemical separation-Shui Ye gold extraction process 1. Mercury-mixed gold extraction is an ancient gold extraction process, which is simple and economical, and is suitable for the recovery of coarse-grained monomer gold. Many gold mines in China still use this method. With the development of gold production and the progress of science and technology, the process of extracting gold with mixed mercury has been continuously improved and perfected. Due to more and more stringent environmental protection requirements, some mines canceled the mercury mixing operation and replaced it with gravity separation, flotation and cyanidation to extract gold. In gold production, the process of extracting gold with mixed mercury still occupies an important position, and there are application examples at home and abroad. At present, the process has been applied in Zhangjiakou, Hebei, Erdaogou, Liaoning, Jiapigou, Jilin, Yinan, Shandong and other gold mines. Erdaogou gold mine in Liaoning Province was originally a single flotation process, and it was changed into a combined flotation process with mixed mercury according to the ore properties. The total recovery rate increased by 7.8 1% (the recovery rate of mixed mercury reached 64.6%), and the tailings grade decreased from 0.74g/t to 0.32g/t, with an annual benefit of 1.58 million yuan. The key to gold extraction by mixed mercury method is how to take protective measures to eliminate mercury pollution. 2. Cyanide gold extraction process Cyanide gold extraction process is the main method to extract gold from ore or concentrate in modern times. The cyanide gold extraction process includes several basic processes, such as cyanide leaching, washing and filtering of leached pulp, extracting gold from cyanide solution or cyanide pulp and smelting of finished products. There are basically two gold extraction processes in the existing gold cyanide plants in China. One is the so-called conventional cyanidation process (CCD method and CCF method) which uses a thickener for continuous countercurrent washing, and the other is the filterless cyanidation carbon pulp process (CIP method and CIL method) which directly absorbs and recovers gold from cyanidation pulp without filtration washing. Conventional cyanidation processes can be divided into two types according to the different materials to be treated: one is cyanidation plants that treat flotation gold concentrates or mixed mercury and gravity separation tailings. This technology is mostly used in large state-owned mines. Such as Jinchangyu, Hebei; Wulong, Liaoning, Yangzhaiyu, Henan; Zhaoyuan, Xincheng, Jiaojia and Sanshandao gold mines in Shandong Province. The other is a gold concentrator, which deals with argillaceous oxidized ore and adopts all-mud stirring cyanidation method. Such as Jilin trench; Tuanjiegou, Heilongjiang; Anhui Xinqiao gold and silver mine and other mines.