In nature, there are more than 200 known copper minerals, but there are only about 17 copper minerals with industrial application value (see Table 25-1-1). Copper has a strong sulfophilicity and copper has an absolute majority. According to the formation conditions and chemical composition of copper minerals, it can be divided into: primary copper sulfide minerals, such as chalcopyrite; secondary copper sulfide minerals, such as chalcopyrite; copper oxide minerals, such as malachite, natural copper, etc. .
Table 1 List of major copper minerals
Copper resources at home and abroad
1 World copper reserves
According to the US Geological Survey estimates that by 2010 the world's terrestrial copper resources of about 540 million tons, the amount of resources of copper and manganese manganese nodules bai knot deep seabed and seamount in 700 million tons, mainly in the Pacific. Further, base metals ocean floor or hydrothermal vents formed sulphides deposits also contain substantial amounts of copper resources. The world copper reserves are shown in Table 25-2-l.
Table: 25-2-l Reserves of major copper producing countries in the world
25.2.2 China's copper resources and their distribution.
According to the statistics of the Ministry of Land and Resources in 2009, as of 2008, the country has identified 1,48 copper mines, among which the famous large-scale copper mines include Jiangxi Dexing Copper Mine, Tibet Yulong Copper Mine, Qulong Copper Mine and Yunnan, which was newly discovered in recent years. Prang Copper Mine. The country has identified a total of 77 million tons of resource reserves (copper metal), mainly distributed in the Sanjiang area of ​​the southwest, the middle and lower reaches of the Yangtze River, the southeast coast, the Qinshao Kun metallogenic belt, the eastern part of the Liaoji black, and the Tongde metallogenic belt in Tibet, namely Jiangxi and Yunnan. In Hubei, Tibet, Gansu, Anhui, Shanxi, Inner Mongolia, Heilongjiang and other provinces (districts), the basic reserves of these nine provinces (regions) accounted for about 81.33% of the country's total basic reserves. The reserves and distribution of copper resources in China are shown in Table 25-2-2.
Table 25-2-2 Status of copper ore resources reserves in China and major regions in 2008 (10,000 tons)
The effect of impurities on copper
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The properties of copper have a great relationship with its purity, and the presence of trace amounts of impurities will greatly affect the performance of copper. The effects of various impurities on copper are as follows:
(1) Arsenic arsenic has little effect on the mechanical properties of copper. Copper containing 0.8% arsenic can be drawn into very fine copper wire. When the arsenic content reaches more than l%, it will cause red heat and fragility. In addition, arsenic has a great influence on the conductivity of copper. Copper contains 0.0013% of arsenic, which can reduce the conductivity of copper by 1%.
(2) Phosphorus Phosphorus in copper can improve mechanical properties, but it is very harmful to the conductivity of copper. Therefore, it is not suitable for phosphorus in copper used for wire manufacturing.
(3) Sulfur and sulfur are present in the form of Cu2S in copper. When the sulfur content in copper is 0.5%, the low temperature is fragile. When the sulfur content is 0.1%, the cracking will occur and the copper will be severely cracked. The bending performance has a great influence. In addition, sulfur-containing copper is liable to generate blisters during casting.
(4) Iron trace iron has little effect on the mechanical properties of copper. When the content reaches 2%, the strength and hardness are slightly increased, but the conductivity is greatly affected, and the ductility and corrosion resistance of copper are both influences.
(5) 锑亦 is also a harmful impurity in copper. When yttrium is at 0.0071%, the conductivity is reduced by 1%. It contains 1% copper, which will crack when it is processed. It will break easily when it is bent slightly.
(6) é“‹å±å®³ is the most harmful to the mechanical properties of copper, containing 0.025% copper, hammering in the case of red heat, that is, cracking or even smashing. The bismuth contained in copper should not exceed 0.005%.
These impurities must be removed as much as possible during the smelting process to reduce the difficulty of refining and machining. In particular, arsenic is extremely harmful to the health of smelters and residents around the refinery. The arsenic minerals must be removed to the maximum during the beneficiation process, so that the arsenic content of the copper concentrate is as small as possible.
Quality standard for copper concentrate
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Copper concentrates are classified into primary, secondary, tertiary, fourth and fifth grades according to their chemical composition. The limits of mercury , fluorine and cadmium impurities in copper concentrates should meet the requirements of national standards (GB2O, 424-2006), and the remaining chemical components should meet the requirements of industry standards, see Table 25-3-1.
Table 25-3-l Copper Concentrate Standard (YS/T318-2007)
Note: 1. Gold and silver in copper concentrate are valuable elements and should be reported as analytical data;
2. The water content (mass fraction) in copper concentrate shall not exceed 12%, and shall not exceed 8% in winter;
3. Do not mix foreign inclusions in copper concentrate. Mixing with the same batch of concentrates;
4. The natural radioactivity limit in copper concentrate should meet the requirements of GB20660-2006.
Copper beneficiation technology and development trend
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1 Copper ore dressing technology
The copper ore exposure oxidation rate (oxidation rate = copper oxide content ÷ total copper content x1o0%) is divided into sulfide ore (oxidation rate less than 10%), oxidized ore (oxidation rate greater than 30%) and mixed ore (oxidation rate) It is 10% to 30%). The main beneficiation method is flotation, and re-election and magnetic separation are also applied. In general, copper sulfide ore, easily selected mixed copper ore and easily selected copper oxide ore are treated by flotation. For refractory mixed copper ore and refractory copper oxide ore, hydrometallurgy or hydrometallurgy combined with flotation is often used.
The commonly used collectors for copper ore flotation are xanthate, followed by black medicines, sulfur nitrogens, esters, combination agents of xanthate and its organic combination, and some code collectors (MAC-l2, EP, MOS). Series, MA series and MB series), etc. The xanthate collectors are mainly ethyl, butyl, isobutyl, isoamyl xanthate and Y89; the black drug collectors mainly include 208, 238, 242, a black drug, and D Amine black medicine, etc.; sulfur nitrogen collectors mainly include SN-9 and OSN-43; ester collectors mainly include Z-200 and S-3302. Commonly used foaming agents are pine oil, oil No. 1l, MI-BC, T-66, Dao 250, Aerofroth 73, 38y and heavy pyridine. Commonly used adjusting agents are sodium sulfide, lime, sodium humate, sodium sulfite, water glass, carboxymethyl cellulose and cyanide.
The common process flow for copper ore flotation is mainly one-stage and multi-stage sorting processes. The representative ones are the stage grinding stage selection process and the stage grinding concentration selection process. In terms of the sorting order, the processes include mixed flotation, preferential flotation, preferential one-step step flotation, fast flotation, step-wise flotation, partial hybrid flotation, and asynchronous hybrid flotation.
As mentioned above, the flotation methods for different types of copper ore are different. The most used one is the vulcanization-xanthate flotation method. In this method, it is easy to choose mixed copper ore and easy to choose copper oxide ore. In the process, inorganic ammonium salts, organic amine salts and their combination agents are often added to enhance the sorting effect. For refractory mixed copper ore and refractory copper oxide ore, due to its low direct flotation technical index and large consumption of chemicals, it is often treated by hydrometallurgy or hydrometallurgy and flotation. For refractory copper oxide ore, it is treated by hydrometallurgy. In the hydrometallurgical process, depending on the leaching agent, there are different methods such as acid leaching, alkali leaching and microbial leaching; in the preparation of the product, there are different methods such as chemical precipitation, displacement precipitation and extraction-electrowinning (see 25.7 li). For the difficult selection of mixed copper ore, it is generally treated by a combination of hydrometallurgy and flotation, which is beneficial to improve the recovery rate of copper and the comprehensive utilization of associated beneficial elements.
　 2 Status of foreign copper beneficiation
Although there are hundreds of copper selection plants abroad, large-scale selection plants are mainly concentrated in Chile, Peru, the United States, Canada, Australia and Zambia. In recent years, although there has been no major breakthrough in foreign copper beneficiation technology, great progress has been made in the use of mineral processing technology, equipment, flotation reagents, automatic control and joint processes. Mainly in the following aspects:
(1) Large-scale plant selection. Chile's Chuquikamata copper- molybdenum ore dressing plant has a production capacity of l5300t/d and an annual output of 500,000 tons of copper. The Escodida copper mine has been expanded several times, and its annual output of copper has exceeded 1 million tons. The mine with the largest copper output.
(2) Large equipment. In the expansion of the l1000t/d scale, the US Ma Ma plant uses a semi-self-grinding-ball milling process to process medium-hard ore. The expansion system uses two φ8500mm x3600mm self-grinding mills and two φ5000mm x5800mm overflow ball mills ; The Pinto Valley copper plant is equipped with a φ5400mm x6400mm ball mill, and each billiard mill and 8 φ660mm cyclones form a closed circuit. Large-scale flotation machines of 100~200m3 are also widely used in copper selection plants.
(3) High level of automation. Due to the size of the plant and the large size of the equipment, the automation requirements are also getting higher and higher. According to statistics, automation can generally increase the capacity of plant selection equipment by 10% to 15%, labor productivity by 25% to 50%, and production cost by 3% to 5%. Therefore, in the newly-built plant, most of the automatic control of the unit or production section or even centralized control of the whole plant is adopted. Computer control has been widely used in more than 30 flotation plants in the United States, the United Kingdom, Canada, Finland, Sweden, Australia, Zambia and the Philippines. Closed-circuit television is often used to monitor the various processes of beneficiation.
(4) Development of high-efficiency pharmaceuticals. For example, Dow's production of copper sulfide minerals is very strong and the ability to capture other minerals is weak; filter aids to increase the filtration effect, grinding aids to increase the grinding effect.
(5) Application of joint process of metallurgy. In order to fully recover useful minerals, a joint process has been developed.
At present, the main problems in copper beneficiation are as follows:
(1) Due to the expansion of the scale of the concentrator and the large-scale equipment, new problems have arisen for the manufacturing and production operation management of the equipment, which requires a higher level of mechanization and automation. Otherwise, the simple equipment enlargement may not bring better. Economic benefits.
(2) New processes and new equipment have many new problems to be solved in practice. For example, flocculation and flotation flotation not only require new agents, but also require fine grinding of ores, and there are still some difficulties in industrial applications.
(3) The original analog amplification algorithm is no longer suitable for large-scale and new equipment.
(4) The proportion of copper mineral resources with complex symbiosis, low grade and fine grain inlay is increasing. The large-scale development and utilization of such copper resources has brought many new problems to be solved.
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