Gold beneficiation and processing technology

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 crushed ore. machine. 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.
(2) Re-election and re-election is widely used in rock gold mines. It is used as an auxiliary process to recover coarse gold in the grinding circuit, creating favorable conditions for flotation and cyanidation processes, improving beneficiation index and improving total gold recovery. The rate has played a positive role in increasing production and 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.
(III) Flotation 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.
(4) Gold extraction process 1. Mercury extraction method Gold extraction The mercury extraction process is an ancient gold extraction process, which is simple and economical, and is suitable for the recovery of coarse monomer gold. This method is still used in many gold mines in China. With the development of gold production and the advancement of science and technology, the gold extraction process of amalgamation has been continuously improved and improved. Due to the increasingly strict environmental protection requirements, some mines have eliminated the amalgamation operation and replaced them with gold extraction processes such as re-election, flotation and cyanidation.
In the gold production, the amalgamation process still has an important role in the gold extraction process, and there are application examples at home and abroad. At present, many gold mines such as Zhangjiakou in Hebei, Erdaogou in Liaoning, Jiapigou in Jilin, and Weinan in Shandong have applied this technology. The Erdaogou gold deposit in Liaoning was originally a single flotation process. According to the ore property, the combined process of amalgamation and flotation was changed. The total recovery rate was increased by 7.81% (the recovery rate of amalgamation was 64.6%) and the grade of tailings was 0.74g/t. It dropped to 0.32g/t and the annual benefit was 1.58 million yuan. The key to the amalgamation process is how to take protective measures to eliminate mercury pollution.
2. Cyanide gold extraction process The cyanidation gold extraction process is the main method for extracting gold from ore or concentrate. The cyanidation gold extraction process includes: cyanide leaching, washing and leaching of the leaching slurry, extraction of gold from cyanide or cyanide pulp, and smelting of the finished product. Gold mines conventional plant of basic cyanide gold extraction process using two types, one is based on gold extraction process thickener continuous countercurrent washing, recovery of gold cementation with zinc powder, a so-called conventional cyanidation (CCD method and CCF The other method is a non-filtered cyanide carbon slurry process (CIP method and CIL method) which does not require filtration and washing, and uses activated carbon to directly adsorb gold from cyanide pulp.
The conventional cyanidation gold extraction process is divided into two types according to the treatment materials: one is a cyanide plant that processes flotation gold concentrate or treats amalgam and re-selects tailings. Most of the processes used are large state-owned mines. Such as Hebei Jinchangyu; Liaoning Wulong, Henan Yangzhaitun; Shandong Zhaoyuan, Xincheng, Jiaojia, Sanshandao gold mine. The other is to treat muddy oxidized ore, using a full mud mixing cyanide gold extraction plant. Such as Jilin trench; Anhui Xinqiao mine gold silver ore; Heilongjiang unity ditch. [next]
China began to use the cyanidation process to raise gold in the early 1930s. During the period from 1936 to 1938, the Jinguashi Gold Mine in Taiwan used gold cyanide-zinc powder replacement process to extract gold, with an annual output of 150,000 gold.
After entering the 1960s, in order to adapt to the development of the national economy, vigorously develop the production of mineral gold. In some mines, intermittent mechanical agitation cyanide gold extraction process and continuous stirring cyanide gold extraction process were used to replace the percolation cyanidation method. Gold extraction process. In 1967, firstly, in the Zhaoyuan Gold Mine Lingshan and Linglong Gold Exchange Plant in Shandong, the continuous mechanical agitation cyanidation process was used to produce gold. The gold extraction by cyanidation method was increased from 70% to 93.23%. From then on, continuous mechanical agitation cyanide gold extraction process The major gold mines across the country were quickly promoted. In 1970, the Jinchangyu Gold Mine and the Wulong Gold Mine Cyanide Plant were completed and put into operation in 1977. Since then, a number of mechanically stirred cyanide plants have been completed and put into operation in China. The cyanidation process has entered a new stage of development.
The continuous development of gold production and the rapid development of gold resources have increased the amount of argillaceous gold-bearing oxidized ore from the 1980s, and developed a study on the full-cyanide agitation of such ore, and in the united ditch of Heilongjiang. The gold mine built a cyanide plant that processes 500 tons of ore per day and put it into production in 1983. Since then, the whole mud cyanidation process has been gradually promoted and applied. It has been used in Henan, Jilin, Hebei, Shaanxi, Inner Mongolia and other places to build factories to raise gold. At the same time, in order to solve the difficulty of muddy oxidized ore in dense filtration solid-liquid separation, in November 1979, the Changchun Gold Research Institute began to use the unfiltered carbon slurry gold extraction process for the ore of the Tuanjiegou gold mine. The two-year experimental study has been successful. On this basis, in August 1984, the Linghu Gold Mine in Henan Province designed and utilized domestically produced equipment to build China's first carbon slurry gold extraction plant that processes 50t ore per day. The process of gold extraction in China's cyanidation process has taken a big step forward. The carbon slurry extraction process has become one of the important methods for the treatment of gold and gold mines for the treatment of muddy oxidized ore. Since then, the charcoal pulp gold extraction plant has been built in Jilin, Henan, Inner Mongolia, and Shaanxi. At the end of 1984, the Gold Bureau of the Ministry of Metallurgical Industry promoted the application of the carbon extracting process in China, transplanted and digested foreign advanced technology and equipment, and cooperated with the United States David McGee in the Xiqiao Gold Mine of Shaanxi Province and Zhangjiakou of Hebei Province. In the gold mine, a carbon leaching gold plant with a daily processing ore of 250t (Xi'an) and a 450t (Zhangjiakou) was built. According to the survey, the Zhangjiakou gold mine reached 93.54% (the recovery rate of carbon slurry in 1988 was 90.25%).
Relying on scientific research and technological innovation, the level of gold production technology in China has been greatly improved. For example, in the Jinchangyu gold mine, zinc powder was used instead of zinc wire to replace the gold mud, so the replacement rate reached 99.89%, the gold grade of gold mud increased significantly, and the zinc consumption decreased from 2.2kg/t to 0.6kg/t. Production costs have been greatly reduced. It has also achieved remarkable results in the promotion and application of mines in Zhaoyuan, Jiaojia, Xincheng and Wulong. The heap leaching process of low-grade oxidized ore has been promoted and applied in Henan, Hebei, Liaoning, Yunnan, Hubei, Inner Mongolia, Heilongjiang, Jilin, Shaanxi and other provinces after the successful trial of the Danshan Hushan gold mine. The economic effect is obvious and low. The development and utilization of grade oxidized minerals has opened the way. According to incomplete statistics, the annual production of gold produced by heap leaching in China has reached more than 10,000 (the total amount of gold produced by heap leaching in Henan Province is 13,000), but compared with developed countries, the scale of heap leaching in China is relatively small. Generally, it is 1×10 ³ to 3×10 ³ t/heap, and there are fewer 10,000 t/heap. There is also a big gap in technology. In 1988, the large-scale 10,000-ton heap leaching site of Shuangwang Gold Mine in Taibai County, Shaanxi Province was put into operation. , achieved gratifying results (ore grade 1.5g / t).
The introduction and digestion of foreign advanced technology and equipment (such as high-efficiency thickeners in the United States, double-spiral stirring and leaching tanks, Japan's Mars pumps, belt filters, etc.) have further advanced China's gold production in terms of equipment level and technical level. The improvement has also promoted the development of China's gold production equipment in the direction of high efficiency, energy saving, large-scale and automation. In the scientific research of new processes such as thiourea gold extraction, thiosulfate gold extraction, pre-oxidation bacteria leaching, pressure catalytic leaching, and resin adsorption, new progress has been made in recent years. In 1979, the Changchun Gold Research Institute successfully carried out the thiourea gold extraction test. In 1984, it built a thiourea gold extraction workshop with a daily processing flotation gold concentrate of 10-20 tons in Guangxi Longshui Mine (in 1987, it passed the ministerial appraisal). . Although other processes are in the experimental research stage and are preparing to start production, it is enough to show that China's gold extraction technology has developed to a new level.
(V) Smelting and Recycling of Gold Gold smelting is the last process in gold production, and its products are finished gold. Smelting has the distinction of refining and refining. The refined and refined products are alloys (commonly known as the combined gold), and the gold mines in China are mostly the prime gold, which is directly sold to the banks. The gold rich ore and various gold concentrates are transported to the non-ferrous smelting plant for processing and refining finished gold (commonly known as gold content). In the 40 years since the founding of the People's Republic of China, gold smelting and comprehensive recycling have developed rapidly, smelting technology and process equipment have been continuously improved, and smelting costs have been decreasing, which has promoted the development of gold production.
1. Gold mine gold local smelting Before the 1970s, gold production was in the initial stage of development. Except for a few mines that began to use the cyanidation process to raise gold, the mines were mainly based on natural gold and fines from sand mine re-election. The smelting of the mine and the mercury paste produced by the amalgamation process are used as raw materials for local smelting. The real estate gold only accounts for 30% of the total output, and 70% of the gold is recycled by the non-ferrous smelter.
After 1970, the production of gold gradually developed, and the gold extraction process of cyanide was increasingly applied. The mines increased the amount of real estate. In 1985, the output of finished gold products accounted for 70% of the national gold production. Most of the mineral products are produced by in-situ cyanidation and smelting.
Most of the local smelting of mines is carried out by traditional smelting method. Due to the different production processes and materials, the gold content of the combined gold is not the same. The direct delivery banks are not high in gold content or silver-free. In order to improve the quality and economic benefits, the mine has adopted chemical separation and remelting or electrolysis to carry out gold and silver separation and refining. In 1984, Jiaojia Gold Mine experimented with the new technology of water smelting. The cadmium gold mud was electrochlorinated to remove bismuth metal (gold extraction by aqueous solution chlorination and ammonia leaching) to obtain gold-containing grade 99.9% finished gold and silver. 99.9% of silver ingots, copper and lead in gold mud are also recovered at the same time (the tendency to be treated by wet treatment of gold mud). Zhaoyuan Gold Mine successfully developed a Φ1.5×1.8m converter smelting gold mud, which replaced the previous smelting, reduced costs and improved working conditions. This method is widely applied in mines such as Shandong Xincheng Gold Mine, and the effect is good. [next]
Zhaoyuan Smelter is the first gold smelter to be researched, designed and constructed by China. It specializes in the treatment of polymetallic sulphide gold concentrates. It mainly extracts gold and recovers silver, copper, lead and sulfur. It is a comprehensive smelting. A new type of enterprise integrating chemical industry. The completion and commissioning of Zhaoyuan Smelter has filled a technical gap for China's gold production and smelting process, using a roasting-acid leaching-(salt leaching)-cyanide leaching process to solve the long-term mining, selection and smelting. Production contradiction, solved the long-distance outbound loss of gold concentrate (annual loss rate 2% to 3%), transportation pressure and comprehensive utilization.
The design of the production process of the plant absorbs the advanced experience at home and abroad. The vacuum belt filter is used as the washing and filtering equipment for the leaching residue. The axial flow cyanide leaching tank is used for three leaching, three solid-liquid separation and leaching slag washing. Advanced process.
2. Recycling of associated gold in non-ferrous smelters In the production of gold, the recovery of associated gold ore associated with gold ore occupies a considerable position. Gold and copper, lead and other non-ferrous metals are selected into the concentrate. In copper and lead smelting, gold and silver are recovered. In order to increase production of gold, some non-ferrous smelters in the country have built precious metal comprehensive recycling workshops. By 1985, there were more than 20 in the country. Apart from Shenyang smelters, there are mainly Zhuzhou, Shanghai, Yunnan, Chongqing, Wuhan and Fuchunjiang. Such as smelting plants and Tianjin, Taiyuan electrolytic copper plant. Among them, the production of companion gold in the three major smelters of Shenye, Shangye and Zhuye accounts for more than 90% of the total output of the national associated gold, which is an important force in China's gold production. The recovery of associated gold in these enterprises is based on the fact that in the process of copper and lead smelting, gold and silver are concentrated in blister copper and crude lead. When electrolytically refining blister copper and crude lead, gold and silver are deposited in the electrolytic anode mud, so it is extracted from the anode mud. Gold and silver are the main ways to recover associated gold and silver.
The treatment process of copper anode mud has been developed rapidly. Through continuous reform and innovation, the traditional fire process is more mature and perfect. The semi-wet process and the whole process are successfully tested and put into production. To make China's smelting technology and equipment level have been greatly improved. Such as the improvement of the fire removal process, the comprehensive recovery of valuable elements, the improvement of the furnace body and the improvement of the vacuum system. There are also the transformation of electrolytic cells, the promotion and application of intermediate frequency furnaces, etc., which have gradually matured and improved the fire smelting process, and improved the technical and economic indicators. Because the fire smelting process has stable technical conditions, mature technology, high comprehensive utilization, strong adaptability to raw materials, large processing capacity, low cost and so on, it is still a smelting plant such as Shenye, Zhuye and Shangye. A universally applied method. Fuchunjiang Smelter, Wuhan Smelter and Chongqing Smelter have achieved remarkable results with the new wet process. Yunnan Smelter and Tianjin Electrolytic Copper Plant have achieved success and put into production through the joint process of metallurgy and smelting, and have also achieved significant economic benefits. The successful test and application of the sulfuric acid slag gold extraction process has also created a new way for China's gold production and full utilization of resources.
(VI) Heap leaching production process Among the gold resources in China, the low-grade oxidized ore accounts for a certain proportion. It is economically uneconomical to use the conventional cyanidation process to treat gold ore, and the heap leaching process still has economic benefits. . Further expanding the scale of heap leaching production in the future is one of the ways to increase China's gold production. In the late 1970s, China began research on the heap leaching production process of low-grade gold-bearing oxidized ore. After successful small-scale production in the Danshan Hushan gold mine in Liaoning, it was successively in Linghu, Yindongpo, Yunnan, Yunnan. Some mines in Mojiang, Chongli, Hebei, and Chifeng in Inner Mongolia have been promoted and applied, and have achieved satisfactory economic results, which has opened the way for the development and utilization of low-grade gold-bearing oxidized ore. Because the heap leaching gold extraction process is simple, the operation is easy, the investment is small, the benefit is good, and the horse is fast, so the heap leaching gold extraction process develops rapidly. In recent years, the State Council and the Gold Corporation have attached great importance to the development of heap leaching production processes. The scale and quantity of heap leaching have seen new growth, and production technology is constantly improving and improving. The application of granulation technology and activated carbon adsorption column and the development of gold-loaded carbon desorption electrodeposition treatment process have added new vitality to the popularization and application of heap leaching gold extraction process.
According to incomplete statistics, there are more than 30 heap leaching sites in 10 provinces and autonomous regions, namely Henan, Hebei, Yunnan, Inner Mongolia, Jilin, Liaoning, Gansu, Guangxi, Shanxi and Hubei provinces, etc. Field service work.
Through small tests, the results of several types of ore heap leaching tests are shown in Table 1 below. It must be pointed out that ore with a grade of more than 3g/t should not be heap leached. This is a waste of resources. The production process indicators of several typical mines in Henan Province are shown in Tables 2 and 3. Table 4 lists the main technical and economic indicators for mining, selection and smelting of gold mines in China. [next]

Table 1

Table 2
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Table 4

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