1. Natural properties of copper

Copper is one of the earliest ancient metals discovered by human beings. As early as 3000 years ago, people began to use copper. Copper in nature is divided into natural copper, copper oxide and copper sulfide. The reserves of natural copper and copper oxide are very small. At present, more than 80% of copper in the world is extracted from copper sulfide ore, and the copper content of this ore is extremely low, generally around 2-3%. Metallic copper, element symbol CU, atomic weight 63.54, specific gravity 8.92, melting point 1083 Co. Pure copper is light rose or reddish. Copper has many valuable physical and chemical properties, such as high thermal 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, iron, etc. The formed alloys are mainly divided into three categories: brass is copper-zinc alloy, bronze is copper-tin alloy, and white copper is copper-cobalt-nickel alloy.

2. Copper smelting

Copper ore mined from copper mine becomes copper concentrate or copper ore with high copper grade after beneficiation, and copper concentrate needs smelting commission to become refined copper and copper products.

A. Copper ore processing

Industrial copper includes electrolytic copper (containing 99.9% ~ 99.95% copper) and refined copper (containing 99.0% ~ 99.7% copper). The former is used to make special alloys, wires and wires in the electrical industry. The latter is used to manufacture other alloys, copper tubes, copper plates, shafts, etc.

A. classification and properties of copper ore:

The raw material of copper smelting is copper ore. Copper mines can be divided into three categories:

(1) sulfide minerals, such as chalcopyrite (CuFeS2), bornite (Cu5FeS4) and chalcocite (Cu2S).

(2) Oxidized minerals, such as chalcopyrite (Cu2O), malachite [CuCO3Cu(OH)2], azurite [2CuCO3Cu(OH)2], chrysocolla (CuSiO32H2O), etc.

(3) native copper. Copper ore with copper content of about 1% (0.5% ~ 3%) has mining value, because some impurities such as gangue in the ore can be removed by flotation, and the concentrate with higher copper content (8% ~ 35%) can be obtained.

B. the smelting process of copper ore;

The process of extracting copper from copper ore is very complicated. Taking chalcopyrite as an example, firstly, concentrate sand, flux (limestone, sand, etc. ) and fuel (coke, charcoal or anthracite) are mixed and put into a "closed" blast furnace for smelting at about 1000℃. Therefore, a part of sulfur in the ore becomes SO2 (used to make sulfuric acid), and most impurities such as arsenic and antimony become volatile substances such as AS2O3 and Sb2O3 and are removed: 2 cufs 2+O2 = cu2s+2 FeS+SO2↑. Part of iron sulfide is converted into oxide: 2fes+3o2 = 2feo+2so2 ↑. Cu2S and the remaining FeS melt together to form matte (mainly formed by mutual dissolution of Cu2S and FeS, with copper content between 20% and 50% and sulfur content between 23% and 27%), and FeO and SiO2 form slag: FeO+SiO 2 = FeSiO 3. The slag floats on the molten matte and is easy to separate, thus removing some impurities. Then move matte into converter, add flux (quartz sand) and blow air for smelting (1100 ~1300℃). Because iron has a greater affinity for oxygen than copper, and copper has a greater affinity for sulfur than iron, FeS in matte is first transformed into FeO, which combines with flux to form slag, and then Cu2S is transformed into Cu2O, and Cu2O reacts with Cu2S to produce crude copper (with a copper content of about 98.5%). 2cu2s+3o2 = 2cu2o+2so2 = 2cu2o+cu2s = 6cu+SO2 = =, then move the crude copper into a reverberatory furnace, add flux (quartz sand), and introduce air to oxidize the impurities in the crude copper, which will form slag with the flux and be removed. After impurities are removed to a certain extent, heavy oil is injected, and cuprous oxide is reduced to copper at high temperature by reducing gases such as carbon monoxide generated by heavy oil combustion. The refined copper obtained contains about 99.7% copper.

B. Copper smelting process

The development of copper-gold technology has gone through a long process, but so far the smelting of copper is still dominated by pyrometallurgy, and its output accounts for about 85% of the world's total copper production. Modern hydrometallurgy technology is gradually popularized, and the introduction of hydrometallurgy greatly reduces the smelting cost of copper. Pyrolysis and hydrometallurgy (SX-EX).

A. pyrometallurgical copper smelting:

Cathode copper, electrolytic copper, is produced by smelting and electrolytic refining, and is generally suitable for high-grade copper sulfide ores. Generally, pyrometallurgical process is to raise the raw ore containing a few percent or a few thousandths of copper to 20-30% as copper concentrate after beneficiation, and carry out matte smelting in a closed blast furnace, reverberatory furnace, electric furnace or flash furnace, and then send the generated matte (matte) into a converter to be blown into crude copper, and then oxidize and refine it in another reverberatory furnace to remove impurities, or the process is short and has strong adaptability. 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.

The production process is roughly as shown in the figure:

In addition to copper concentrate, waste copper is one of the main raw materials for copper smelting, including old waste copper and new waste copper. Old copper scrap comes from old equipment and machines, abandoned buildings and underground pipelines. The new scrap copper comes from the scrap copper abandoned by the processing plant (the proportion of copper production is about 50%), and the supply of scrap copper is generally stable. Waste copper is divided into: bare copper: the grade is above 90%; Scrap copper (wires): copper-containing materials (old motors, circuit boards); Copper produced from waste copper and other similar materials is also called recycled copper.

B. copper hydrometallurgy:

A ship is suitable for low-grade copper oxide, and the refined copper produced is called electrodeposited copper. 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.

The wet smelting process is as follows:

C. Comparison of characteristics between pyrometallurgy and wet process Compared with pyrometallurgy and wet copper production process, pyrometallurgy and wet copper production process have the following characteristics:

(1) The smelting equipment of the latter is simpler, but the impurity content is higher, which is a beneficial supplement to the former.

(2) The latter is limited by the grade and type of ore.

(3) The cost of the former is higher than that of the latter.

It can be seen that wet smelting technology has considerable advantages, but its application scope is limited, and not all copper mines can adopt this technology. However, through technical improvement, in recent years, more and more countries, including the United States, Chile, Canada, Australia, Mexico and Peru, have applied this process to more copper smelting. The improvement of hydrometallurgy technology and the popularization of its application have reduced the production cost of copper, improved the productivity of copper mines, and increased the supply of social resources in a short time, resulting in a relative surplus of total social supply, which has a pulling effect on prices.

3. Production and consumption of copper

A. Distribution of copper resources: The world copper resources are mainly distributed in North America, Latin America and Central Africa. At present, the proven reserves in the world are 350 million tons, of which Chile accounts for 24%, the United States accounts for 16.9%, the Commonwealth of Independent States accounts for 10. 15%, Zaire accounts for 7.39% and Zambia accounts for 4.55%. Copper production in China is concentrated in East China, accounting for 5 1.84% of the national total, of which Anhui and Jiangxi provinces account for about 30%. The main consumption areas of copper are East China and South China, accounting for about 70% of the total consumption in China.

B. Main uses of copper:

Copper is a red metal and a green metal. The reason why it is a green metal is mainly because it is durable and easy to be remelted and remelted, so recycling is quite cheap.

In 1960s, the biggest market for copper was electrical appliances and electronic products, accounting for about 28% of the total. From 65438 to 0997, these two markets became the second largest end users of copper consumption, accounting for 25%. In many electrical products (such as wires, buses, transformer windings, heavy-duty motors, telephone lines and telephone cables), the service life of copper is quite long, and it will take 20 to 50 years for the copper inside to be recycled. The service life of other copper-containing electrical appliances and electronic products (such as small electrical appliances and consumer electronic products) is relatively short, generally 5- 10 years. Commercial electronic products and large electrical appliances are usually recycled because they contain other precious metals besides copper. Nevertheless, the recovery rate of small electronic consumer products is still very low, because there is almost no copper in them.

With the rapid development of science and technology in the field of electronics, some outdated copper-containing products are becoming more and more outdated. For example, in the 1980s, telephone exchanges and central business offices were the main sources of copper and copper alloy waste, but the appearance of digital conversion made these heavy metal-intensive things more and more outdated.

Transportation equipment is the third largest market for copper, accounting for about 13% of the total, which is basically the same as that in the 1960s. Although the importance of transportation has not changed, the use of copper has changed greatly. For many years, automatic radiator is the most important end user in this field; However, the usage of copper in automatic electrical appliances and electronic products has increased rapidly, while the usage in heat exchanger market has declined. The average service life of a car is 10- 15 years. Almost all copper (including radiator and wires) was recovered before it was disassembled and recycled.

Industrial machinery and equipment is another major application market, in which copper usually has a long service life. However, the usage of copper in this market has not increased, and now it only accounts for 12% of the total usage, compared with 2 1% in the 1960s. The relative importance of consumer goods and general products also dropped from 13% in the 1960s to 9% in the 1970s. Coins and weapons are the main end users in this field. Bullets are rarely recycled, some coins can be melted, and many coins are kept by collectors or savers and cannot be recycled.

C. Copper resource recovery

Copper is quite durable. It is conductive and usually does not corrode or deteriorate over time. So copper is often used to produce products with long service life. 1997 The consumption of copper by the construction industry accounts for about 42% of the total copper consumption in the United States, which is 22% higher than that of 1960. At present, the use of copper at home has also increased significantly compared with the past 50 years or 100 years ago.

The infrastructure of the building can be expanded or modernized, but the copper wire, copper tube and brass fittings in the home or office hardly need to be replaced. Because of the long service life of copper, and the copper contained in the home is less than that contained in the current building structure, there is only a small amount of copper chips in the building and construction industry.

Compared with steel, aluminum and plastic, the recovery rate of old copper scrap (that is, the ratio of the consumption of old copper scrap to the total consumption of copper) is relatively low for copper wire, copper tube and copper fittings for construction. The reason is that the packaging products (the main end users of steel, aluminum and plastics) have only a few weeks' cycle and can be recycled several times a year. On the other hand, copper products generally have a long service life. This affects the supply of copper scrap for recycling.

Attachment: Copper rebounded in the US market

Copper and copper alloys are easy to recycle. 1450,000 tons of copper were recovered from the waste processed in the United States in 1997. In the same year, the United States also exported 379,000 tons of copper and copper alloys. The total amount of primary refined copper extracted by the United States from domestic mineral deposits and foreign raw materials is 20 tons. About 2/3 of copper-bearing debris is new debris, and 1/3 is old debris.

The United States has developed infrastructure, which can provide copper scrap to smelters, smelters, copper rolling plants, foundries, ingot plants and other places. These factories need copper chips for processing or cost saving. In 1997, about 19% of copper is treated in the furnace. Most copper smelting in the United States comes from primary smelters related to mining operations. Most of these factories do not use copper sheets, although some use a small amount of copper sheets to control the temperature of copper liquid in the converter. There are two intermediate smelters in the United States, Chemetco in Illinois and Southern Power Equipment Factory in Georgia, which mainly process copper scrap. The raw materials of these factories are all old copper scraps without impurities, and these old copper scraps must be upgraded before recycling.

Most primary refineries in the United States rely on copper and anode as their main raw material supply sources. However, a few refineries still process high-grade 1 copper slag or buy copper foam or anode from copper slag. Generally speaking, the molten cast block or the negative electrode obtained from secondary raw materials cannot be used anywhere. Most of these raw materials are used in copper rolling mills. The secondary cathode may not be suitable for producing thin wires, so it was originally used only for producing household wires. Some secondary cathodes are also mixed with the cathodes of primary furnaces to produce other wires and cables.

South Cable Factory uses high-grade waste copper to produce cathodes, which are used to produce wires and cables together with outsourced cathodes. Warren Refinery is another copper scrap processing plant, which mainly produces pyrometallurgical ingots. Reading industry and Cerro copper industry operate and manage waste copper processing plants that provide raw materials for pipe-making plants. Both Noranda and Asarco in Canada use high-grade copper scrap in their primary smelters. Copper scrap processed by American refineries accounts for about 10% of copper recovered in the United States.

Copper factory is the largest consumer of copper scrap in the United States, accounting for more than 50% of the total consumption of copper scrap in the United States. These copper factories use scrap copper and alloy scrap copper. These raw materials must be advanced, because it is only to be smelted again without any refining. A lot of copper scrap is new. For example, a large part of the waste copper used in alloy bar factory is copper recovered by consumers. The recycled copper scrap is also the main source of raw materials for copper strip and sheet manufacturers, but the pipe factory uses the purchased copper instead of the taxed copper. On average, these fragments contain about 56% of the raw materials needed by copper rolling mills in the United States.

Ingot plants and foundries rely on scrap copper to obtain copper. In 1997, scrap copper accounts for 93% of their copper demand. Generally speaking, the requirements for producing casting products are not as strict as those for producing gold-plated platinum products or wire-drawn products, so ingots and foundries can use low-grade copper and copper alloy wastes for production.

Copper has high intrinsic value, which makes the recovery of copper quite economical. The infrastructure needed by debris collectors, traders, processors and consumers is not supported by the municipal government, and there are no incentive projects.

When copper factories recycle copper scrap from consumers, the price of the copper scrap is only 90% of the price of the metal in the copper scrap. For example, when the copper rod factory adjusts the price, they will set a "selling price value of brass rod metal" and a "consumer recycling price". In the futures market in the United States, the price of scrap copper is generally slightly lower than the copper price set by Comex trading market.

4. Factors affecting copper prices

A. the international economic situation. The correlation between commodity market and economic situation is obvious, especially with the globalization of world economy, the correlation between commodity market and economy is stronger, so copper price is closely related to economic situation. The consumption of copper is mainly concentrated in developed industrial countries. The economic conditions of the United States, Japan, Western Europe and other countries have a great influence on copper prices. Generally speaking, when the economic situation is good, the demand for copper increases, and the price goes up, and vice versa.

B. production in the producing country. Chile is the country with the richest copper resources in the world and the largest copper exporter. Zambia and Zaire in Central Africa are also important copper producers. Almost all the copper they produce is used for export, and their production has a great influence on the international copper market. The political situation in these three countries has been unstable, and labor disputes often break out, which also has a direct impact on copper prices.

C. seasonal effects. The seasonal fluctuation of copper price is obvious, and it is lower every year 1 month and higher in August.

D. the impact of industrial policies. Because copper is mainly used in power, electronics, construction, machinery, transportation and other industries, the national industrial policies for these industries have a more important impact on copper prices.

E. the price of alternatives. Copper has always been an important raw material in the telecommunications industry. However, due to the popularization and application of optical fiber technology, the status of copper cable has been challenged. At the same time, metal materials such as aluminum have the same properties as copper and have replaced copper in most application fields.

F. Impact of inventory. Inventory is one of the important factors affecting copper prices. Under different market conditions, enterprises will take different measures to increase or decrease inventory. In order to ensure the production of raw materials or speed up the flow of funds, the government will also use throughput reserves to stabilize the copper market in different periods.

G. the impact of other policies and regulations. As the copper market is an international market with a large volume of international trade, increasing the import and export policies, exchange rate systems and efforts to crack down on smuggling in relevant countries will also have an impact on copper prices.

5. Characteristics of domestic copper price trend

Copper futures trading has been officially launched in China since1March 1993 1 1. It is one of the more standardized and mature trading varieties in China, and its price has become an important guiding price for domestic copper spot trading. Looking at the trend in recent years, domestic copper futures prices have the following characteristics:

A. The market trends of Shanghai Metal Exchange and London Metal Exchange (LME) are consistent and influence each other;

B. Shanghai Gold Exchange has its own technical characteristics and has not lost its independence:

C. Compared with other varieties, the price fluctuation of copper futures is relatively small, and it is difficult for large households to maliciously manipulate the market and forcibly hold positions.

6. Classification of copper and copper products

A. Classification according to the forms existing in nature

Natural copper-the copper content is above 99%, but the reserves are very small;

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.

B. Classification by production process

Copper concentrate-an ore with high copper content selected before smelting.

Crude copper, the product of smelting copper concentrate, contains 95-98% copper.

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.

C. Classification by main alloy components

Brass-copper-zinc alloy

Bronze copper-tin alloy, etc. Except for zinc and nickel, the alloy of other elements is called bronze.

White copper-copper-cobalt-nickel alloy

D, classified by product form: copper tube, copper rod, copper wire, copper plate, copper strip, copper strip, copper foil, etc.

7. Product number and quality standard of copper

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.