Brief introduction of copper
I. Natural attributes
Copper is one of the earliest ancient metals discovered by human beings. As early as 3000 years ago, people began to use copper. & ltbr & gt
Metallic copper, element symbol Cu, atomic weight 63.54, specific gravity 8.92, melting point 1083oC. Pure copper is light rose or reddish, and its appearance is purple after copper oxide film is formed on its surface. Copper has many valuable physical and chemical properties, such as high thermal and electrical conductivity, mechanical stability, high tensile strength, easy welding, corrosion resistance, plasticity and ductility. Pure copper can be drawn into thin copper wire and made into thin copper foil. It can form alloys with metals such as zinc, tin, lead, manganese, cobalt, nickel, aluminum and iron.
The development of copper smelting technology has gone through a long process, but so far copper smelting is still dominated by pyrometallurgy, and its output accounts for about 85% of the world's total copper output. 1) Pyrometallurgical smelting is generally to raise the raw ore containing a few percent or a few thousandths of copper to 20-30% through mineral processing, make matte as copper concentrate, smelt it in a closed blast furnace, reverberatory furnace, electric furnace or flash furnace, and then send the matte (matte) produced to a converter for smelting into coarse copper, and then blow it into another reverberatory furnace. The process is short and adaptable, and the recovery rate of copper can reach 95%. However, the sulfur in the ore is discharged as sulfur dioxide waste gas in matte making and blowing stages, which is difficult to recover and easy to cause pollution. In recent years, molten pool smelting such as Baiyin process and Noranda process, as well as Mitsubishi process and pyrometallurgical process in Japan, have gradually developed to continuity and automation. 2) Modern hydrometallurgy includes sulfation roasting-leaching-electrowinning, leaching-extraction-electrowinning and bacterial leaching, which is suitable for heap leaching, tank leaching or in-situ leaching of low-grade complex ores, copper oxide ore and copper-bearing waste ores. Wet smelting technology is being gradually popularized, and it is expected to reach 20% of the total output by the end of this century. The introduction of hydrometallurgy greatly reduces the smelting cost of copper.
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Two. Classification of copper and copper products
1, classified according to the forms existing in nature
Natural copper-the copper content is above 99%, but the reserves are very small; & ltbr & gt
Copper oxide ore-Very few.
Copper sulfide ore-copper content is extremely low, generally around 2-3%. More than 80% of the world's copper is extracted from copper sulfide ore.
2. According to the production process classification
Copper concentrate-an ore with high copper content selected before smelting. & ltbr & gt
Crude copper, the product of smelting copper concentrate, contains 95-98% copper. & ltbr & gt
Pure copper-copper with more than 99% content after smelting or electrolysis. 99-99.9% pure copper can be obtained by smelting, and the purity of copper can reach 99.95-99.99% by electrolysis.
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3, according to the main alloy composition classification < br >
Brass-copper-zinc alloy
Bronze copper-tin alloy, etc. (Except for zinc and nickel, alloys of other elements are called bronze.)
White copper-copper-cobalt-nickel alloy
4. Classification by product form: copper tube, copper rod, copper wire, copper plate, copper strip, copper strip, copper foil, etc.
Third, the quantity and quality standard of copper products
1 Before September 1997, the quality standard of the subject matter of copper futures contracts was GB466-82, and the delivery product was1copper. 1September 1997 to1August 1998, GB466-82 and GB/T-467-1997 were implemented at the same time, and GB/T467- 1997 standard was from1September 1998. br & gt
1, chemical composition of standard cathode copper (copper -CATH-2)%
Copper+silver & ltbr & gt
Not less than impurity content (not more than)
Arsenic, antimony, bismuth, iron, lead, tin, nickel, zinc and phosphorus & ltbr & gt
99.95 0.00 15 0.00 15 0.0006 0.0025 0.002 0.00 1 0.002
0.002 0.0025 0.00 1 & lt； br & gt
2. Chemical composition of high-purity cathode copper (Cu-CATH- 1): Cu+Ag is not less than 99.95, and the total impurity content is not more than 0.0065 (the classified impurity content is omitted).
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Fourth, the main uses of copper
Copper is a non-ferrous metal closely related to human beings, which is widely used in electric power, light industry, machinery manufacturing, construction industry, national defense industry and other fields. It is second only to aluminum in the consumption of non-ferrous metal materials in China. & ltbr & gt
Copper is widely used in electrical and electronic industries, accounting for more than half of the total consumption. & lt& lta href="#top " >top & lt/a & gt； & gt& lt/TD & gt；
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& ltTD style = " line-height: 150%；" & gt< font color = "# ff0000" >< strong & gt Introduction of copper scrap:
Copper, gold and silver belong to the same family in the periodic table of elements, so they have excellent physical and chemical properties similar to precious metals. Good plasticity, easy processing, corrosion resistance, no magnetism, beautiful and durable. Especially the electrical conductivity and conductivity of copper.
It is the best of all metals except silver. In engineering, the conductivity of annealed pure copper is defined as 100%, which is calibrated by other materials and called IACS value (international standard value of annealed copper). Because the conductivity of copper is very important for trace impurities.
It is very sensitive, so IACS value can be used as an index of copper purity in production. The IACS value of high purity copper can reach 10 1.5%. The IACS values of high purity aluminum (99.996%) and industrial pure aluminum (99.5%) are 64.94% and 64.94% respectively.
59%。 That is to say, in the application of electrical engineering, the conductivity of copper is more than 35% higher than that of aluminum. & ltbr & gt
Copper can alloy with many other metals. For example, the alloy of copper and zinc is called brass, the alloy of copper and nickel is called white copper, and the alloy of copper and elements such as aluminum and tin is called bronze. Adding alloying elements to copper can
Improve its strength, hardness, elasticity, machinability, wear resistance and corrosion resistance to meet different use requirements. & ltbr & gt
Among all metals, copper has the best regeneration performance. Copper scrap is an important source of raw materials for copper industry. & lt& lta href="#top " >top & lt/a & gt； & gt& lt/TD & gt；
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& ltTD style = " line-height: 150%；" & gt< strong & gt< fontcolor = "# ff0000" > Main sources of copper scrap:
According to its source, there are two types of copper scrap. & ltbr & gt
One kind is new waste copper, which is the waste produced in the production process of copper industry. Metallurgical plant is called "the copper scrap of our factory" ("home
Scrap ") or" recycling copper scrap "("detour "). Scrap copper produced by copper processing plants and directly returned to suppliers are called "industrial scrap copper", "spot scrap copper" ("prompt") or new scrap copper.
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The other is old copper scrap, which is discarded after use, such as abandoned or removed from old buildings and transportation systems. Copper and copper-based materials, whether exposed or wrapped in the final product, can be recycled at all stages of the product life cycle. Generally speaking, more than half of the waste copper used for regeneration is new waste copper. About 1/3 of all waste copper is returned to the market in the form of refined copper after reprocessing, and the other 2/3 is reused in the form of impure copper or copper alloy. The premise of direct application of copper scrap is strict classification, stacking and sorting. The direct application of waste copper has the advantages of simplified process, simple equipment, high recovery rate, low energy consumption, low cost and light pollution. The amount of waste copper directly used generally reflects the level of copper regeneration in a country. In contrast, the direct utilization rate of copper scrap in China is relatively low, about 200,000 t per year, accounting for only 30%~40% of the total copper scrap recovery. The production of brass processing materials is mostly operated by township enterprises, which greatly reduces the economic benefits and brings future troubles to energy consumption and environmental protection.
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China imports copper scrap mainly from the United States, Japan, Germany and Russia, among which the United States ranks first, and the United States has strict regulations on the management of copper scrap. This paper takes the classification standard of America as a typical introduction. Copper scrap in America is classified according to its purity. The American Institute of Scrap Metal Recycling even subdivided copper and its alloys into 53 categories.
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In the United States, the copper material containing more than 99% Cu is usually called 1 copper, which can be directly remelted and used without further processing. Copper with a minimum copper content of 94.5% is called No.2 copper. This waste copper must be remelted before it can be used in the form of metallic copper. Other common classification brands are lead brass, brass and low zinc brass, shell brass, automobile radiator, high copper brass (red brass), high-speed cutting brass and so on, which are widely used. Automobile waste is directly regenerated and used to reprocess brass products. It is in the form of alloy and has the same composition. For manufacturers, its main advantage is that it greatly reduces the cost of net metal consumption. Waste copper is also used to produce copper chemicals, but it is difficult to obtain quantitative data.
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At present, there is no standard for scrap copper in China, but with the acceleration of industrialization in China, the social and economic environment faced by the recycling, trading and recycling industries of scrap nonferrous metals has changed greatly. Not only has the variety composition of waste non-ferrous metals changed greatly, but foreign waste non-ferrous metals and various available wastes have flooded into China, providing a rich source of raw materials for the production of non-ferrous metals in China, and also putting forward new requirements for the production and processing of recycled non-ferrous metals. Therefore, China is also stepping up the formulation of scrap metal standards. The Classification and Technical Conditions of Copper and Copper Alloy Wastes, which was compiled by the Recycling Metals Branch of China Nonferrous Metals Industry Association, has been included in the national technical standard revision plan. The new classification standard of waste nonferrous metals will refer to the classification standard of waste nonferrous metals in the United States and the technical standard of European classification, and be revised according to the actual situation of China's recycled nonferrous metals industry, so as to make it more conducive to the implementation of enterprises and management departments. The revision of this standard is expected to be completed by the end of 2002.
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For detailed standards of copper scrap, please refer to the national waste standards. & lt& lta href="#top " >top & lt/a & gt； & gt& lt/TD & gt；
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& ltTD style = " line-height: 150%；" & gt< strong & gt< fontcolor = "# ff0000" > Recovery and treatment methods of copper scrap:
In fact, all copper scrap can be recycled. The regeneration process is very simple. First, the collected copper scrap is classified. The unpolluted waste copper or copper alloy with the same composition can be used directly after melting in the furnace; seriously polluted
Waste copper should be further refined to remove impurities; For copper alloy scrap mixed with each other, it is necessary to adjust the composition after melting. Through this regeneration treatment, the physical and chemical properties of copper are not destroyed, but completely updated. Recycling waste copper should be treated in two steps. The first step is to dry and burn off organic substances, such as engine oil and grease. The second step is to smelt metal and remove metal impurities from slag.
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Copper scrap is of high value because it can be regenerated. For example, the price of clean 1 grade waste copper can reach more than 90% of the price of newly refined copper; The price of new brass scrap can also reach more than 80% of the corresponding brass price.
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The world's scrap copper processing technology and equipment have formed advanced scrap copper processing technology represented by tilting furnace refining and ISA electrolysis. The Hutong Vickaiser Factory (HK) of the West German Refinery Company (NA) is the largest and most advanced copper scrap refinery in the world, which uses a tilting furnace (350 tons/ft) and a reverberatory furnace.
(200 t/f) processing waste copper, using ISA process to produce cathode copper (DK = 3 13A/m2), the production capacity is170,000 t/a ... American waste copper recycling technology.
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Compared with foreign advanced recycling technology, the overall level of waste copper pretreatment and recycling technology and equipment is backward, and the two links of waste copper pretreatment and recycling are decoupled. Up to now, there is no complete copper scrap factory in China, from dismantling copper scrap to cathode copper refining. The copper scrap refinery is small in scale, backward in technology, poor in equipment and serious in environmental protection. So far, there is no modern copper smelting factory or workshop in China. The scale of these factories is generally 0.5-30,000 tons, and pyrometallurgical refining basically adopts reverberatory furnace, which can
25- 1 10 ton, this kind of furnace has low thermal efficiency, high energy consumption, serious black ash pollution during reduction operation and high labor intensity of workers. The product quality can only reach or even be lower.
Grade of standard cathode copper in GB/T467- 1997 standard. A considerable part of high-grade copper scrap is directly made into copper ingots and copper "Hei Bang" without refining.
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The joining of large domestic copper enterprises such as Jiangtong, Yuntong, Tongling and Daye, which mainly deal in copper concentrates, will inevitably intensify the competition of domestic copper scrap raw materials and impact small and medium-sized copper scrap enterprises.
Jiangtong will introduce advanced inclined anode furnace and establish a special copper processing workshop as an important measure to realize the tenth five-year plan of the company. & ltbr & gt
China copper scrap recycling and processing industry must take the road of healthy development of technological progress. & lt& lta href="#top " >top & lt/a & gt； & gt& lt/TD & gt；
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& ltTD style = " line-height: 150%；" & gt< strong & gt< fontcolor = "# ff0000" > consumption and distribution of recycled copper at home and abroad;
The demand for copper in many countries depends largely on recycling copper to meet domestic demand. For example, the consumption of copper in the United States ranks first in the world. During the 20 years from 65,438+0,976 to 65,438+0,996, the copper provided by copper scrap recycling accounted for the annual copper amount.
The consumption ratio is 44% to 54.7%. In Europe, there is a shortage of copper resources. In addition to importing a large number of copper concentrates, we have to rely on waste copper as an important supplement. According to statistics, 1997 recycled copper accounts for 42.6% of the total raw materials. Among them, 22.4% of waste copper is directly utilized and 20.2% is refined again.
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China is a country with poor copper resources and the second largest copper consumer in the world. The solution to the contradiction between lack of resources and sharp increase in consumption is to import a large number of copper raw materials. After the 1990s, China's imports of scrap copper increased rapidly. In the past two years, China's foreign exchange for scrap copper reached 2.25 billion US dollars, which was used to import copper concentrates in the same period.
1.32 times. China is one of the largest importers of copper scrap in the world, and its main sources are countries and regions with developed industries and strict environmental protection requirements, among which the proportion of imports from the United States and Japan is 38% and 25% respectively. In addition, it is estimated that there are still
654.38+0.5 million tons of self-produced copper scrap. In China's copper smelting industry, the ratio of copper ore raw materials to waste copper raw materials is 2.69: 1, and the proportion of waste copper in copper raw materials has reached 27%.
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China has formed three key areas for dismantling, processing and consumption of waste copper, namely Yangtze River Delta, Bohai Rim and Pearl River Delta. The refined copper output in these areas is lower than the total copper output.
40%, but its recycled copper output accounts for 75.55% of the national recycled copper output. 79.43% of copper processing enterprises in China are located in these three areas, and 82.95% of copper consumption in China is in these three areas, especially in Jiangsu, Zhejiang and Shanghai provinces. In Zhejiang Province, during the three years from 1998 to 2000, the output of copper processed timber reached10 million tons.
65,438+0,246,5438+0,600 tons, accounting for 30% of the national copper processing timber output in the same period. In 2000, there were 2 large-scale copper processing enterprises and 29 medium-sized copper processing enterprises with an annual output of more than 50,000 tons of waste copper in Zhejiang Province. 55 small copper processing enterprises with a production capacity of 0.5-0.5 million tons. The number of large and medium-sized copper processing enterprises only accounts for 2.33% and 33.72% of the total number of enterprises, while the waste copper used by large and medium-sized copper processing enterprises accounts for 2 1.80% and 52.78% of the total utilization. The utilization of scrap copper has formed a pattern with large enterprises as the leader and medium-sized enterprises as the main body, and gradually developed into a number of scrap copper professional markets with large dismantling and trading volume, such as Luqiao in Taizhou, Zhejiang, Anxin in Hebei, Qingyuan in Guangdong, Yixing in Jiangsu and Suzhou.