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) Re-election
Gravity separation is widely used in rock gold mines, mostly as an auxiliary process for recovering coarse gold in grinding circuit, which creates favorable conditions for flotation and cyanidation processes, improves mineral processing indexes, improves the total recovery rate of gold, and plays a positive role in 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 investigation, 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 beneficiation-Shui Ye gold extraction process.
1. Gold extraction by mixed mercury method
The process of extracting gold from mixed mercury is an ancient process, simple and economical, and suitable for the recovery of crude 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
Cyanidation 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.
As early as 1930s, China began to extract gold by cyanidation. During the period of 1936 ~ 1938, Taiwan Province Jinguashi gold mine used cyanide-zinc powder replacement process to extract gold, with an annual output of152,000.
After 1960s, in order to adapt to the development of national economy and vigorously develop mineral gold production, some mines adopted intermittent mechanical agitation cyanidation process and continuous agitation cyanidation process instead of percolation cyanidation process. 1967 realized the continuous mechanical agitation cyanidation process for the first time in the concentrator of Lingshan and Linglong gold mines in Zhaoyuan Gold Mine, Shandong Province, and the cyanidation gold extraction increased from 70% to 93.23%. Since then, continuous mechanical agitation cyanidation process has been rapidly popularized in major gold mines in China. 1970 jinchangyu gold mine and 1977 Wulong gold mine cyanidation plants were built and put into operation one after another, and then a number of domestic mechanical agitation cyanidation plants were built and put into operation one after another, and the cyanidation process of gold extraction entered a new development stage.
Since 1980s, with the continuous development of gold production and the rapid development of gold resources, a large number of gold-bearing oxide ores with high argillaceous content have appeared. The research on all-slime cyanidation and agitation leaching of this kind of ore was carried out, and a cyanidation plant with a daily processing capacity of 500t ore was built in Tuanjiegou Gold Mine of Heilongjiang Province, which was put into operation on 1983. Since then, the whole mud cyanidation process has been widely used to extract gold in Henan, Jilin, Hebei, Shaanxi, Inner Mongolia and other places. At the same time, in order to solve the difficulty of solid-liquid separation in dense filtration of argillaceous oxidized ore, Changchun Gold Research Institute began to extract gold from Tuanjiegou gold mine by carbon slurry method in June 5438+0979165438+10. The experimental study lasted for two years and was successful. On this basis, in August of 1984, the first gold extraction plant with a daily processing capacity of 50t was designed and built in Linghu Gold Mine, Henan Province. The cyanide gold extraction process in China has taken a big step forward. Gold extraction from carbon slurry has become one of the important methods to treat argillaceous oxidized ore. Since then, gold extraction plants have been built in Jilin, Henan, Inner Mongolia, Shaanxi and other places. At the end of 1984, the Gold Bureau of the Ministry of Metallurgy established a 250t (Xitongyu) gold mine in Shaanxi Province and a 450t (Zhangjiakou) gold leaching plant in Zhangjiakou, Hebei Province, respectively, in order to popularize the application of carbon slurry gold extraction technology in China and transplant and digest foreign advanced technology and equipment. According to the investigation, the recovery rate of Zhangjiakou Gold Mine is 93.54% (the recovery rate of1988 carbon slurry is 90.25%).
According to Science, the experimental research of technological innovation has greatly improved the technical level of gold production in China. For example, the replacement of gold mud with zinc powder instead of zinc wire was successful in Jinchangyu Gold Mine, so that the replacement rate reached 99.89%, the gold grade of gold mud was obviously improved, the zinc consumption was reduced from 2.2kg/t to 0.6kg/t, and the production cost was greatly reduced. Subsequently, it was popularized and applied in Zhaoyuan, Jiaojia, Xincheng, Wulong and other mines, and achieved remarkable results. The heap leaching technology of low-grade oxidized ore was successfully tested in Hushan Gold Mine in Dandong, and has been popularized and applied in Henan, Hebei, Liaoning, Yunnan, Hubei, Inner Mongolia, Heilongjiang, Jilin, Shaanxi and other provinces, with obvious economic effects, which opened the way for the development and utilization of low-grade oxidized ore. According to incomplete statistics, the annual output of heap leaching gold in China is more than 22,000 (only 65,438+3,000 in Henan Province), but compared with developed countries, the scale of heap leaching in China is relatively small, generally1×103 ~ 3×1003t/heap.
Introduce and digest foreign advanced technology and equipment (such as American high-efficiency thickener, twin-screw stirring leaching tank, Japanese Mars pump, belt filter, etc.). ) further improved the equipment level and technical level of China's gold production, and also promoted the development of China's gold production equipment in the direction of high efficiency, energy saving, large-scale and automation. In recent years, the research of new technologies such as thiourea extraction, thiosulfate extraction, pre-oxidation bacterial leaching, pressure catalytic leaching and resin adsorption has also made new progress. 1979 The experiment of thiourea gold extraction in Changchun Gold Research Institute was successful. 1984 A thiourea gold extraction workshop was built in Guangxi Longshui Mine, with a daily processing capacity of10 ~ 20t (1987 passed the ministerial appraisal). Although other processes are in the experimental research stage, ready to build a factory and put into production, it is enough to show that the gold extraction technology in China has developed to a new level.
(5) Gold smelting and recovery
Gold smelting is the last process of gold production, and its product is finished gold. Smelting can be divided into rough refining and refining. After finishing and rough machining, the products are all alloy (commonly known as alloy gold), and most of the real estate gold mines in China are alloy gold, which are sold directly to banks. Gold-rich ore blocks and various gold concentrates are transported to non-ferrous smelters for processing and refining finished gold (commonly known as content gold). Over the past 40 years since the founding of the People's Republic of China, gold smelting and comprehensive recovery have developed rapidly, the level of smelting technology and process equipment has been continuously improved, and the smelting cost has been reduced day by day, which has promoted the development of gold production.