According to different leaching systems, copper leaching methods mainly include acid leaching, ammonia leaching, chlorine elimination, electrochemical leaching and enhanced leaching. Among them, acid leaching technology has been widely used in production, and other technologies are mainly in the laboratory research stage. At present, the main problem in the presence of a copper leaching process are: (l) acid leaching chalcopyrite passivation process prone to the phenomenon, is difficult to efficiently extract; (2) Large Copper oxidation of limestone ore type complex, the content of Ca, Mg High, it is difficult to achieve effective recovery by acid leaching.
In recent years, a large number of basic theories and applied research have been carried out on these problems, and the main progresses have been made: (1) It reveals that the existence of sulfur and sulfide is the main cause of the passivation phenomenon of chalcopyrite, and proposes The leaching rate of chalcopyrite was improved by controlling the solution potential or adding Ag + ; (2) A new type of ammonia leaching hybrid ligand system was developed to treat limestone copper ore, and the normal temperature and atmospheric pressure ammonia leaching extraction process was optimized, and Based on this, the "ammonia leaching-extraction-electrowinning" process was developed.
1 Development of copper leaching technology
A acid leaching
In view of the problem of difficult leaching of chalcopyrite, the researchers found that the presence of sulfur and sulfide is the main cause of passivation on the surface of chalcopyrite by acid leaching test of chalcopyrite. There is a significant "passivation" phenomenon in the process of sulfuric acid or Fe 3+ leaching of chalcopyrite under normal temperature conditions. Shu Rongbo et al. have shown through experiments that the mineral leaching product sulfur is more likely to be "passivated". The release of copper and iron ions during the leaching process leads to the collapse of the original crystal structure. The SS, S and the inner minerals are fastened together by a dense chemical bonding to form H + and Fe 3+ (both Hydrated ions) films that are difficult to penetrate.
Lu Yiping et al. studied the special electrochemical decomposition behavior of chalcopyrite by cyclic voltammetry and constant potential It curve. It was found that when the cathode negative potential reached a certain value, Fe 3+ was completely reduced and formed a stable solid product Cu 2 S. This intermediate substance does not easily fall off, and a faster anodization reaction can occur at the oxidation potential, but then a passivation layer Cu x S is formed. Therefore, creating a reducing environment for the leaching process can effectively change the leaching effect.
CÓrdoba et al. investigated the effect of solution potential on chalcopyrite leaching at 68 °C. It was concluded that when the initial potential of the leaching solution was 300 mV.400 mV and not less than 500 mV (vs. Ag/AgCI), the leaching was performed. The leaching rates of copper in the first 5 days were greater than 80%, greater than 90%, and less than 40%, respectively. Vilcáez et al. believe that when the solution potential is greater than 450mV (v.Ag/AgCI), chalcopyrite is directly oxidized by Fe 3+ in solution. When the solution potential is less than 450mV (vs, Ag/AgCI), chalcopyrite first forms the middle. The product, the intermediate product, is further oxidized to release copper ions. Vilcáez and lnoue believe that the dissolution of chalcopyrite involves both cathodic reduction and anodization: when the initial Fe 3+ concentration in the solution is higher, the oxidation rate of chalcopyrite is greater than the reduction rate; conversely, the initial Fe 2+ concentration in the solution At higher temperatures, the rate of reduction of chalcopyrite is greater than the rate of oxidation. Therefore, when chalcopyrite is leached at low [Fe 3+ ]/[Fe 2+ ] or low solution potential conditions, the copper release rate is controlled by Fe 2+ concentration rather than Fe3 2+ concentration because The presence of Fe 2+ is critical to the formation of chalcopyrite.
The presence of Ag 2+ can significantly increase the leaching rate of copper in chalcopyrite. CÓrdoba et al. studied the effect of Ag + and solution potential on chalcopyrite leaching at 35 °C. When the leaching potential is controlled to 600mV (v.Ag/Agcl) and no Ag + is added, the copper leaching rate is less than 3%, and when lg Ag/kg Cu ​​Ag + is added to the solution, the copper leaching rate is greater than 90%. . Meanwhile, when Ag + lg Ag/kg Cu ​​is present in the solution, the leaching rate of copper increases as the leaching potential increases.
When Ag + is adsorbed onto the surface of the chalcopyrite, A + forms Ag 2 s with S 2 in the chalcopyrite crystal lattice, thereby releasing copper and iron in the chalcopyrite crystal lattice into the solution, and when Fe 3+ is present Ag 2 S is oxidized to Ag + and S 0 by Fe 3+ or dissolved O 2 in the solution to achieve recycling of Ag 2+ .
Shu Rongbo and others have proved through experiments that Fe 2+ is more effective than Fe 3+ leaching for the Dahongshan chalcopyrite in Yunnan. This may be because Fe 2+ creates a strong reducing environment. Under such strong reducing conditions, the adsorption of Fe 2+ on the surface of chalcopyrite provides an effective way for electron transfer between O 2 and chalcopyrite.
The acid leaching process includes heap leaching, column immersion, tank leaching and agitation leaching due to differences in ore properties, grades and occurrence states. Heap leaching is one of the main ways of copper acid leaching. It has the advantages of fast leaching speed, high leaching rate and low acid consumption. There are many factors affecting heap leaching, such as particle size, height of immersion pile, and way of stacking. Optimizing these process parameters can improve leaching rate and leaching rate.
Huang Ruiqiang et al. found through experiments that the leaching speed of heap leaching copper is faster. Under the same grain size, compared with other leaching methods, heap leaching copper has higher leaching rate, low acid consumption, lower iron leaching rate, and fine mud. The resulting interference is also small. In the copper oxide heap leaching test, Xi Yong et al found a linear relationship between the ore size and the leaching rate. On the basis of analyzing the influencing factors of the permeability of high mud ore heap, Wang Shaoyong et al. proposed to adopt a water washing-classification process to successfully increase the permeability coefficient of the leach heap to 8 to 50 times that of the original ore, and to make the comprehensive leaching rate less than 10% increased to 63.98%. Padillas et al. found that the height of the immersion pile and the operation time can affect each other through optimization of the copper heap heap leaching process. Wang Yuming et al. proposed to reduce the content of fine particles (powder ore below 5mm) in the dumping site, change the way of pile-up, improve the pore structure distribution of the pile, and effectively reduce the porosity of the fine particles percolation and sedimentation. The effect of permeability improves the leaching effect. Li Xianghong and others have done similar work. In addition, in view of the problem that the surface of the ore is prone to fouling during the heap leaching process and affects the leaching rate, Yan Jialong et al. studied the acid leaching process of a high-altitude high alkali copper ore in Yunnan and found that the scale is dominated by CaSO 4 . The reason for this is that the leaching process continuously generates Ca 2+ and introduces SO And it was verified that the anti-scaling agent effectively inhibits ore scaling by chelation solubilization and crystal distortion. In the study of the leaching of a low-grade, fine-grained cobalt -containing and copper tailings, Liang Jianlong et al. found that the use of LN3 as a binder granulation greatly improved the permeability of the ore, increased the leaching rate and reduced the acid consumption. .
At present, the study of column leaching mainly focuses on the grain size distribution of ore, especially the influence of mud content on the leaching process, and proposes different solutions to solve the problem of low leaching rate due to high mud content. Yan Xiuxiu et al. found in the square column immersion test that the mineral mud characteristics have a great influence on the permeability of the pillar, especially in the initial stage of leaching; the sedimentation of the sediment has no significant effect on the permeability of the pillar. Wu Hao et al. conducted a full-grain column leaching and washing-mineral column leaching-slurry agitation test on the oxidized zone ore of the Yulong copper mine in Tibet, which can effectively improve the leaching rate of copper. Ding Xianjie et al. used the combination of coal and activated carbon as the catalyst to study the effect of spray intensity on the acid leaching of Yongping low-grade primary copper sulfide ore by column leaching test. Yan Jialong et al. investigated the copper and iron leaching effects and acid consumption of different ore sizes in the column leaching expansion test of the Yangla copper deposit in Yunnan.
In addition, researchers have made some progress in the study of tank leaching and stirring leaching. Gao Baosheng et al. found that the ore of 0.295~1 mm grade can be leached by the tank leaching process in the fractional acid leaching test of a high-mud copper oxide ore. The leaching rate of copper can reach 70.27%. . In the stirring leaching test of mud-alkaline high-grade low-grade copper oxide ore in Shuikou Mountain, Hunan Province, Zhao Guodong and others found that the leaching rate of ore with a leaching rate of only about 60% under normal conditions can reach 80% after heating and stirring. about. Sun Jingfeng et al. studied the leaching of a copper oxide ore with a high mud content in Inner Mongolia with sulfuric acid under normal temperature and pressure. Du plans to optimize the experimental parameters of the stirring acid leaching process for the copper oxide ore in Yuexi, Anhui Province.
B ammonia leaching and chlorine leaching
Because large-sized limestone copper oxide ore has the characteristics of complex ore type and high calcium and magnesium content, the use of acid leaching to treat such ore has the disadvantages of high acid consumption and heavy pollution. Therefore, some researchers have carried out ammonia leaching for this type of ore. the study. The progress of ammonia leaching is mainly as follows: (1) research on a new type of ammonia leaching mixed ligand system; (2) optimization of normal temperature and atmospheric pressure ammonia leaching extraction process, and on the basis of this, developed "ammonia leaching - extraction - electrowinning" new technology.
Zhang Yu concluded in the production practice of high-calcium-magnesium low-grade copper oxide ore by ammonia heap leaching: using ammonia heap leaching-extraction-electrowinning process to treat high calcium magnesium oxide ore, from technology and economy Both have certain feasibility and rationality. Ma Jianye et al. studied the leaching of Yunnan Tangdan high alkaline low grade copper oxide tailings in NH 3 ·H 2 O-(NH 4 ) 2 CO 3 system.
Zhao Guodong et al. used the tailings of the Baifang Copper Mine in Hunan as the research object, and used the (NH 4 ) 2 CO 3 -NH 3 -H 2 O system for heap leaching for the high alkaline low grade copper oxide ore. Mao Yingbo et al. conducted an ammonia leaching test on the Xinjiang copper oxide copper ore and conducted a comprehensive systematic investigation of various factors affecting copper leaching. Fang Jianjun et al. studied the influencing factors of normal temperature and atmospheric ammonia leaching of oxidized copper ore in Yunnan Dongchuan Tangdan, and determined the optimum leaching conditions for normal temperature and atmospheric pressure ammonia leaching. Liu Dianwen and others have developed a new high-efficiency "normal temperature and atmospheric pressure ammonia extraction" - electrowinning-leaching flotation process for the Dongchuan Tangdan refractory high calcium magnesium oxide copper mine. Zhou Xiaodong et al. investigated the effect of microwave on the ammonia leaching of low-grade refractory copper oxide ore. The results show that the total copper leaching rate of microwave irradiation ammonia leaching is significantly higher than that of non-microwave conditions, and microwave refractory copper oxide ore. Ammonia leaching has obvious catalytic effect; in the conventional (non-microwave condition) leaching process, leaching once every time with microwave irradiation can greatly increase the copper leaching rate of the ore sample, but the total leaching time required is also increased accordingly. .
Chlorination is mainly directed to the leaching of complex sulfide ore. Huang Min et al use oxidation of ferric chloride in an acidic environment of the sulfide ore leaching, then by substitution, filtration, crystallization, extraction processes effectively separate the valuable metals lead, zinc, copper, silver minerals And gold, comprehensive recovery of ferric chloride and sulfur.
C other enhanced leaching
In view of the difficulty in recovering copper in copper tailings, the researchers have obtained better indicators by introducing electrochemical beneficiation and ultrasonic enhanced leaching.
Copper can be effectively extracted from copper tailings and low-grade copper ore by electrochemically leaching copper. Zhang Yunqi et al. studied the comprehensive utilization of copper tailings and low-grade copper ore by electrochemical leaching method, which made the extraction rate of copper as high as 96.2%. The ultrasonic enhanced tailings ammonia leaching test by Zhang Jie et al. showed that the shock wave and microjet formed under ultrasonic strengthening can create a new active surface and improve the mass transfer effect in the “dead zone†of leaching, and significantly improve the tail. Sand leaching rate and total leaching rate. Qin Jia et al. explored the effect of surfactant on the leaching of copper ore. The results show that the surfactant-specific amphiphilic structure can cause the surface tension of the solution to decrease at the interface, thereby enhancing the ability of the solution to wet and penetrate the ore. Thereby increasing the copper ion leaching rate. Padilla et al. studied the leaching of chalcopyrite in a sulfuric acid-oxygen system, which increased the copper dissolution rate significantly when the partial pressure of oxygen increased, but at the same time reduced the selectivity.
2 Development of copper organic extractant
The chemical leaching-extraction-electrowinning process for recovering copper from copper-containing materials can achieve the current development status, which is inseparable from the achievements in the research and development of copper efficient organic extractant.
The study on the extractant N902 has a large proportion in the copper extractant, and N902 shows a higher extraction rate and better selectivity in most of the experimental studies. Liu Shuping used the domestic extractant N902 to extract and separate Cu 2+ from the high sulfuric acid content leaching solution of copper, zinc and iron polymetallic ores. It was verified that N902 was used as extractant to extract from high copper, high zinc and higher sulfuric acid solution. Separating copper can obtain better process specifications. Yu Li et al. tested the extraction conditions of copper leaching solution, and the optimal extraction result was N902 as the extractant. Xu Jianlin et al. used N902 extractant to extract and separate divalent copper from the ammonium chloride system leaching solution. The effects of extractant concentration, extraction ratio and shaking time on copper extraction rate were investigated.
In addition, studies on extractants M5640, LIX984, and ZJ988 have also shown their feasibility for copper extraction separation. Yu Xiaohua et al. studied the process of separating Cu 2+ from high copper high zinc sulfuric acid solution by M5640-kerosene extraction system. Hou Xingang et al. studied the acid leaching solution of low-grade copper ore and studied the properties of two new copper extractants, M5640 and LIX984, for extracting copper. Chen Yongqiang et al. found in the separation of copper and cobalt from ammonia solution with different extractants. It is technically feasible to extract copper and cobalt from ammonia solution with LIX984N and LIX54-100, and LIX54-100 More economical. Yao Xujie et al.'s research on the synthesis of five kinds of Schiff ba ses showed that the extraction temperature and extraction time had little effect on the extraction rate of copper ions. Most SchifF bases only had good values ​​in the high pH range. Extraction performance, and the extraction effect of DHAA 2,3,4-trihydroxybenzaldehyde is equivalent to that of N902. On the basis of elucidating the chemical structure of the main components of copper extractant hydroxyketone oxime and aldose oxime, Luo Zhongyan et al. [ researched the anti-oxidation and anti-oxidation mechanism of multi-substituted phenolic antioxidants on free radicals, and found copper extraction. The anti-oxidation stability of the agent ZJ988 and LIX984N is the same.
With the advancement of mineral processing technology and equipment, the new process of copper chemical beneficiation has been developed. Wang Hui introduced the in-situ blasting leaching wet method copper extraction technology to mine the low grade refractory copper oxide ore in the No. 5 ore body of the copper ore mine. This technology has “hole mesh liquid, static penetration, grouting and sealing, comprehensive liquid collectionâ€. "The characteristics." Wu Yidong et al. used the heap leaching-stirring leaching-extraction-electrowinning process to recover copper metal from the copper ore resources of the Yulong copper mine II ore. It was found that the eutrophic copper resources with an average grade of more than 3.5% for the Yulong copper mine are now available. There are processes to achieve continuous and stable production, the leaching rate can reach more than 90%; the oxidized ore of the II ore body line 3 is densely washed by stirring and leaching, the copper recovery rate can reach over 95%, and the electrolytic cathode copper The quality has reached the standard of the first grade copper in GB/T467-1997. Liu Dianwen et al. developed a high-efficiency smelting and smelting new technology for the treatment of high-calcium-magnesium oxidized copper ore in Dongchuan Tangdan with “normal temperature and atmospheric pressure ammonia extraction-electrowinning-dip flotationâ€.
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