The traditional process of gold smelting and the re-election of new technology re-election is the most traditional method of gold extraction. Because of its simple process and low cost, it is effective for trapping monomer renting gold. Therefore, the process still dominates the gold extraction of sand mines. However, in recent years. The re-election process is very rapid for the gold extraction of rock gold mines. Several large or new large-scale rock gold mines in foreign countries have used re-election method to extract monomer gold in the grinding circuit. Some rock gold mines in China also have applications, and all have received good results. Improvements and innovations in re-election equipment have driven the development of re-election gold extraction processes. Such as the successful development of the movable chute, the round jig, the Nielsen concentrator using the centrifugal force field, and the successful agitating chute and STL type water jacket centrifuge developed in China, the recovery rate of re-election is further improved, and it has received obvious effect. Flotation gold extraction process From the 1950s to the 1970s, in addition to gold, China's gold production basically uses the flotation method to produce concentrates, and then sends them to the smelting plant to produce finished gold. This method is still the most economical and rational process for sulfide ore containing metals such as gold, copper , lead , zinc, etc. It can realize the comprehensive utilization of polymetallics. After the 1980s, the flotation gold extraction process has developed greatly and has entered a new level. Flotation of new equipment and new pharmaceuticals In recent years, due to the emergence of new flotation equipment and new flotation reagents, the flotation recovery index (grade and recovery rate) has been continuously improved. For example, the flotation column has been applied in developed countries, which has brought the flotation process to a new level. China has improved the old-fashioned A-type flotation machine, and developed high-efficiency flotation machines such as SF type, BS-K4 type, JJF type, QF type and CHF-Y type, which make the concentrate grade and recovery rate different. The degree of improvement. For example, after a BS-K4 flotation machine was used in a gold mine in Henan, the concentrate grade was increased from the original 17.44 g/ton to 24 g/ton, and the tailings grade was reduced from 0.55 g/ton to 0.3 g/ton. The use of new flotation reagents and combination medications has greatly improved flotation conditions and enhanced harvesting capacity, thereby increasing flotation recovery and reducing drug consumption. For example, a copper mine in Jiangxi used the advanced xanthate collector Y-89, which effectively improved the selection of copper, silver and sulfur, especially the recovery rate of associated gold increased by 2.5%. And the total amount of the agent was reduced by 46 g/t. A copper mine in Hubei uses P-60 mixed with isobutyl xanthate to use flotation sulfide ore. The gold recovery rate was increased by 5.77%. Flotation combined process The single flotation process has not adapted to the increasingly complex ore properties, and the development of the beneficiation and gold extraction process technology has formed a trend toward the development of joint process. Such as re-election - flotation process, flotation - cyanidation process (concentrate or tailings cyanidation), cyanidation - flotation and re-election (flotation) - carbon leaching process in gold mines at home and abroad Universal application. For example, the re-election-flotation process can overcome the shortcomings of the difficulty in collecting and collecting the rented grain. A gold mine in Hebei belongs to a gold-bearing polymetallic deposit with a daily treatment capacity of 300 tons/day. The process adopted is flotation-concentrate cyanide--separation separation process, which achieves the purpose of comprehensive recovery of polymetallics. In view of the ever-changing nature and increasing complexity of the ore, the use of the combined beneficiation process can indeed maximize the recovery index. This is a very beneficial way for China's gold mines, especially the old mines that have been in operation for many years, to tap the potential for comprehensive recovery. . Cyanide gold extraction process At the beginning of the 20th century, cyanide gold was promoted and applied in industry. About 80% of the world's new gold mines are currently raised by cyanidation. How to shorten the leaching time, further increase the leaching rate and reduce the consumption of cyanide is a subject that people are constantly researching and exploring. Therefore, the current development of the process has reached a fairly high level internationally. Improvement of cyanide gold extraction process (1) An oxidizing agent (pure oxygen or oxide) is used in the leaching process and an oxygen-added carbon immersion process such as oxy-resin leaching is extended. The benefits of using auxiliary oxidants: one is to effectively increase the leaching rate of gold and silver; the second is to speed up the leaching speed and shorten the leaching time; the third is to reduce the consumption of cyanide and reduce the amount of lead nitrate. The leaching rate of the Longtoushan gold mine in Guangxi was increased by 4.31%. The use of auxiliary oxidants has been widely promoted throughout the world as the best technology for optimizing the cyanidation process. (2) The copper-gold ore was leached with an ammonia-cyanide system and succeeded in a small tailings treatment plant abroad in 1986. In the experimental study of improving the copper-bearing gold concentrate in Hunchun, the ammonia-cyanide system was used for leaching, which significantly increased the gold leaching rate to 38.98%. For cyanide leaching of gold-copper ore and copper-bearing concentrates, this technology will show strong vitality. (3) The side edging process can enhance the leaching effect. For example, the 216 Geological Team of Shanxi Geological Survey Bureau recently used TW type tower grinder to immerse and immerse arsenic refractory gold concentrate in side blasting. The treatment capacity is 30 tons/day, and the grinding fineness is 95%-98%- Under the 400 mesh condition, the gold leaching rate increased by 8%. If the tower grinding machine is used to implement the edge grinding and immersion process in gold mines, it will be a major innovation in the cyanide gold extraction process. Development of gold recovery process from cyanide leachate Gold is recovered from cyanide leachate (or pulp), and the three major processes of industrial production are mature, namely zinc powder replacement process; activated carbon adsorption process and ion exchange resin process. The activated carbon adsorption process is more economical and effective, and the ion exchange resin process has become a latecomer with its superior physical and chemical properties, and has been rapidly developed. Nevertheless, the zinc powder replacement process is very beneficial in the treatment of silver-containing ores and gold-containing solutions. In developed countries, in the pulp system, the development trend of activated carbon adsorption is carbon leaching. High-strength, wear-resistant coconut shell charcoal is commonly used in carbon. The carbon analysis is widely used in the Zade process. In recent years, the application of the heating and pressure analysis process and the cyanide-free analysis process have been promoted. China's Laojiaoshan gold mine in Heilongjiang Province successfully adopted a cyanide-free analytical process, which can save 33 tons of solid sodium cyanide, worth 530,000 yuan. The ion exchange resin process is widely used in Eastern European countries. The development and application of new resins has become the core of the forward development of resin pulp technology. The use of new anion exchange resins and chelating resins greatly improves the resin adsorption properties. Xinjiang Axi Gold Mine is the first large-scale gold mine in China to introduce resin gold extraction technology, with a production scale of 750 tons/day. The production practice proves that the resin has high mechanical strength and low wear, and the consumption of the resin is only 25 g/ton; the adsorption capacity of the resin is high and the adsorption speed is fast; the concentration of the adsorbed pulp is 5%-7% higher than that of the carbon slurry method. This also shows that the resin slurry method is superior to the carbon slurry method in many aspects, and it is worthy of being promoted and applied in China. Research and application of non-ammonia leaching agent Cyanide dissolves gold, which is highly undesirable because it is highly toxic. For many years, attempts have been made to replace it with other less toxic leaching agents. In recent years, great progress has been made in this area. The leaching agents developed include thiourea, chlorine, bromine , iodine , nitrogen, thiocyanate, and thiosulfate, which are more industrially significant. It is a thiourea and bromine. Thiourea immersion gold has a lot of research results at home and abroad, sulfur gland leaching gold is fast, non-toxic, not sensitive to harmful elements such as copper and arsenic, it may become the most promising solution for industrial production except cyanide. Gold pharmacy. The problem that hinders the industrial application of thiourea is the high consumption of chemicals; the leaching pulp is acidic, and the leaching equipment needs to be preserved; the lack of an excellent method for effectively recovering gold and silver from thiourea solution has no economic advantage compared with cyanide gold extraction. . Therefore, it is currently limited to small-scale industrial applications (processing high-grade gold concentrates). Recently, Minmet of Ireland has developed a new process for immersion gold with thiourea. The process has undergone significant improvements in adsorption, recovery and solution recycling. Thereby reducing the loss of thiourea and improving the leaching and precipitation efficiency. The process is suitable for ore of various grades, and has lower power consumption and less reagent usage than the cyanidation method. Save on environmental governance costs. Suitable for small-scale mining applications. Brominated gold extraction is likely to be the most promising leaching process to replace cyanide gold. Great Lake Chemical Company, in order to evaluate the effect of bromine and cyanide leaching gold, systematically studied the bromination gold extraction process. The results show that bromine is superior to cyanide as a gold leaching agent. Mainly in the following aspects: (1) the price is cheap. (2) The leaching rate is high. The same leaching rate (90%-95%) as that of cyanide leaching gold can be achieved. (3) The leaching speed is fast. Leaching with 4 h was equivalent to leaching with cyanide for 24 h to 48 h. (4) It is non-toxic and non-corrosive at low concentrations. (5) The medicament can be recycled. (6) It is convenient to recover gold from the solution, and the recovery process by cyanidation method can be employed. In order to fill the gap in bromination and gold extraction technology, the company has been conducting research work. Although the application of bromine is still at a relatively early stage, as time goes by, the Australian gold extraction process will gradually be recognized and accepted by people. The advantages of the process will also be verified by industrial production. Heap leaching gold extraction process The heap leaching gold extraction process is currently considered to be the most economical gold extraction method. Production practice shows that the infrastructure investment of the heap leaching production mine is about 25% of the construction plant. Production costs are only 35%-40% of the cost required compared to the more economical carbon slurry process. A large part of the increase in gold production in the world's major gold producing countries in recent years comes from heap leaching. At present, the production scale of heap leaching has been enlarged, and the heap leaching technology has also developed in depth. The scale of production continues to expand, and the level of impregnation is gradually reduced. At present, the international large-scale heap leaching plants include the Yanacocha gold mine heap leaching plant in Peru and the RoundMountain gold mine leaching plant in the United States. The Yanacocha gold mine heap leaching plant processes 1.36 million tons of ore per month with an average gold grade of 1.4 g/t. The Round Mountain gold heap leaching plant has a daily processing capacity of 45,000 tons and an average gold grade of 1.1 grams/ton. The largest heap leaching plant in China is the Zijinshan Gold Mine in Fujian Province. The annual processing of ore is 2.6 million tons, and the grade of human immersion ore is 1.4g/ton-1.7g/ton, and the leaching rate is 70%. Improvement of mining step granulation technology The application of granulation technology has brought the heap leaching and gold extraction process to a new level. By using granulation technology, heap leaching and gold extraction can be carried out for ore with poor permeability, argillaceous minerals and abandoned tailings. In addition, cyanide is added during the granulation process to make the cyanide and the ore more evenly contacted to enhance the leaching effect, which is also an innovation of granulation technology. Add an auxiliary agent to increase the leaching rate. Shorten leaching time (1) Pure oxygen and calcium peroxide will be used in the heap leaching process. The results of column immersion test show that the process can improve the heap leaching recovery rate, shorten the leaching period, and reduce the oxide consumption and water consumption. (2) Adding a surfactant to significantly improve the leaching effect. The addition of this surfactant, the leaching test of the broken siliceous oxidized ore, the leaching rate increased by 24%; the leaching rate of the argillaceous ore was increased by 4%. Gold extraction technology for difficult metallurgical ore Difficult to treat gold ore refers to gold ore with low direct leaching rate of gold, which is generally less than 80%. The typical leaching rate of typical refractory ore is only 10%-30%. The main causes of infiltration are fine-grained gold and gold-coated, as well as harmful impurities such as arsenic and carbon in the ore. Such ores need to be pretreated for rational use and economic benefits. There are many methods of treatment, such as calcination, pressure oxidation, biological oxidation, and other chemical oxidation methods. Calcination pretreatment technology Calcination oxidation is an older pretreatment method, especially for ores with high sulfur content and high arsenic. This method is self-heating and can be recycled. It is an ideal method. With the advancement of technology and the needs of the market, this method has achieved new development in recent years. In the early days, there were multiple furnace roasting, rotary kiln roasting, and muffle furnace roasting. The oxidizing and roasting of gold ore in a boiling furnace began in 1947. The two-stage boiling furnace roasting and the raw ore circulating boiling furnace roasting method were commercialized in the past ten years. Two-stage roasting, cycle roasting, and evolving pyrolysis-oxidation roasting method, flash roasting method, and microwave roasting method all aim at solving environmental protection, reducing energy consumption, increasing leaching rate, and increasing roasting strength. The roasting oxidation method is characterized by strong adaptability, but with the improvement of environmental protection requirements, the cost of exhaust gas treatment is increased, and this method is challenged by the wet pretreatment method. There are 11 major manufacturers that use boiling furnace roasting abroad, and they are roasting in raw ore circulating boiling furnace and roasting in two-stage boiling furnace. For example, IBM in the United States has adopted the two-stage roasting method with the lowest investment and operating cost for the treatment of partially wrapped gold and coal-containing ore. A mine in Hunan Province and a mine in Xinjiang have also been pretreated by roasting for the treatment of high arsenic gold concentrate. Pressurized oxidation pretreatment This method involves pretreating the ore with pressurized oxidizing acid leaching or by pressurized alkaline leaching. First remove the harmful impurities such as S, As, Sb in the ore, fully expose the gold mineral, and then recover the gold by cyanidation. The requirements of environmental protection and the requirements of gold leaching rate have promoted the development of pressurized oxidation. This method was first applied to the Homestake, Mclanlgh gold mine in 1984 and has since grown rapidly. At present, there are 11 representative pressurized oxidation plants in foreign countries. Ultra-fine grinding--low-temperature low-pressure oxidation refractory gold ore technology is a technology developed by Australia's Dominion Minerals Co., Ltd. Through ultra-fine grinding, the mineral surface activity is improved, the oxidation temperature and pressure are reduced, and the reactor material and anti-corrosion problems become smaller. The future of development. Biological oxidation pretreatment technology Biooxidation pretreatment is a mechanism in which bacteria can oxidize and leaching elements such as sulfur, arsenic, and iron , thereby exposing the encapsulated gold to create conditions for the next step of gold extraction by cyanidation. Bio-oxidation technology is applied in gold industrial production to solve refractory gold ore. Pre-oxidation and gold extraction is an environmentally-friendly high-tech developed rapidly in the 1990s. At present, there are six bio-oxidation-cyanide gold-plating plants in the world, and the production scale has grown from 40 tons/day to 960 tons/day, and the gold leaching index has reached 90%-95%. The supporting technologies, such as process control, online inspection, equipment structure and materials, are constantly being improved and optimized. The production practice proves that the process is effective for treating gold refractory gold ore, not only with considerable economic benefits, but also with significant environmental and social benefits, showing good industrial development prospects. The research on bacterial oxidation-cyanide gold extraction process in China has developed rapidly in recent years. Changchun Gold Research Institute has done a lot of experimental research work. Systematic research was carried out with the focus on the typical Fengcheng refractory gold ore. Breakthroughs have been made in strain selection, process flow, technical indicators, and equipment development. The gold leaching rate reached 95.02%, which was 91.61% higher than the conventional cyanidation, and obtained a very ideal technical and economic index. In 1999, small experimental studies and expanded trials were completed and technical results were identified. At present, two biological oxidation-cyanide gold extraction plants have been put into operation in China. Chemical oxidation pretreatment technology Nitric acid oxidation The nitric acid oxidation method uses nitric acid as a medium to bring oxygen in the air into the slurry under normal pressure and oxidize pyrite and arsenopyrite. The oxidized product NO2 and water form nitric acid and are returned for use. According to reports, Canada has successfully carried out small continuous tests and set up a semi-industrial test plant to treat arsenic pyrite containing gold-bearing refractory ore. Electrochemical oxidation Electrochemical oxidation is the use of electrode reactions to oxidize pyrite and arsenopyrite. The electrochemical oxidation method is basically the same as the oxidation oxidation and bacterial oxidation of pyrite and arsenopyrite, which causes the mineral to form iron arsenate, iron sulfate and the like to dissociate gold. Compared with other methods, this method does not bring air pollution, there is no high pressure problem, and the oxidation speed is faster. Therefore, research on electrochemical oxidation has received attention. Russia has carried out an electrochemical pretreatment expansion test of 500 kg/batch scale. Australia has also conducted experimental studies on electrochemical oxidation of arsenopyrite. Gold and silver refining technology With the development of hydrometallurgical processes and the requirements of the international gold market for the quality of gold products, traditional pyrometallurgical techniques are rarely used alone. At present, chemical methods, electrolysis methods, and extraction methods are popularized and applied for their high purity, low environmental pollution, short refining cycle, and the ability to recover a variety of precious metals. Boliden precious metal refining process The precious metal refining process invented by Boliden is to refine silver with high current density and to refine gold by two-step precipitation. The advantages of Boliden precious metal refining process are: (1) Fast and efficient. For silver refining, 5, gold refining only uses 3. Therefore, the accumulation of metal time in the process is half the cost of conventional methods. (2) The recovery rate of smelting is high. The total recovery of silver is greater than 99.5%, and the total recovery of gold is greater than 99.8%. (3) High product quality. Up to 1# standard gold and silver quality. Gold iodine refining process Japan uses an iodized gold refining process to quickly obtain 1# gold. The advantages of the gold iodization refining process are: (1) no waste gas and waste water are produced. (2) The process is operated only with electrical energy. (3) The process speed is about 3-5 times faster than the electrolysis method. (4) 1# gold can be obtained. Gold chlorination refining process The gold chlorination refining process offered by Denver Mining Engineering Company is quite different from conventional refining technology. The process has a solid-gas high-temperature chlorine gas reactor, and the gold ingot is contacted with chlorine gas under a micro-negative pressure condition. When operating under special process conditions, the chlorine gas reacts with silver, zinc, mercury and other mixed gold impurities to form a chloride. Gold is produced in elemental form and then cast. The advantages of this process are: (1) low investment and production costs. (2) Processing speed is fast. (3) The recovery rate is high and the loss is less than 0.1%. (4) The operation is quite simple. (5) There is almost no deposit in the system. However, the limitation of this process is that platinum cannot be separated from gold and the material is required to contain at least 5%-10% gold. Improvement of gold and silver refining process in China Domestic gold and silver refining, chemical methods, chemical methods - fire method and electrolysis method are used in large-scale smelters. In the small and medium-sized gold mines, the pyrometallurgical process has been extended, and the gold recovery rate is low and the quality is not high. In recent years, as the gold market will gradually open up and participate in international market competition, the quality requirements of the state for gold are also increasing. Therefore, various large smelters, especially gold mines, have begun to pay attention to the improvement of gold and silver refining and purification technology. For example, Shandong Zhaoyuan Gold Smelting Group Co., Ltd. has abolished the traditional converter pyrometallurgical process, and currently uses an acidification reduction electrorefining process. The quality of gold and silver has greatly improved. Conclusion Re-election has become one of the important gold extraction methods for rock gold mines with its outstanding advantages. The development and application of re-election of new equipment has promoted the development of re-election technology. The emergence of new flotation equipment and new pharmaceuticals has promoted the development of flotation and gold extraction technology. However, the single flotation can not meet the increasingly complex ore properties, and the combined process of various methods and methods can maximize the recovery of valuable metals. Since cyanide gold is effective and the recovery effect is the best, the cyanide gold extraction process will still dominate in the gold production field. Instead of cyanide gold technology, development research should be strengthened. Because heap leaching can make full use of resources and recover gold at low cost, it will still be widely used in gold mines. The calcination method, the pressurized oxidation method, and the biological oxidation method each have their own advantages and disadvantages, and are industrially coexisting. The biological oxidation method and the microwave oxidation method have the most application prospects because of their good environmental effects. The traditional pyrometallurgical can not meet the requirements of the international gold market, so various refining processes have been produced one after another, but the refining technology with high recovery rate, low production cost, light environmental pollution and short production cycle has more application value. 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The status quo and development direction of gold smelting technology in China
Our rich gold reserves, wide distribution, dotted with gold producers, covering large surface, so the gold smelt technology complete. There are conventionally used smelting techniques, as well as difficult smelting techniques in recent years, and some new technologies such as non-cyanide leaching agents and chemical oxidation methods have also been studied and discussed. The advancement of metallurgical technology has promoted the development of China's gold industry. At present, China's gold production ranks fifth in the world and has become one of the major gold producers, and some technical fields have reached or approached the world's advanced level. The following is an introduction to the status quo and development direction of China's gold smelting technology.