Copper: One of the first metals discovered by man. Archaeological discoveries in tombs have shown that as early as 6,000 years ago, Egyptians were using copper tools. Copper in nature can be found as native copper, cuprite and chalcocite. Native copper and cuprite are scarce.
Today, more than 80% of the world's copper is refined from chalcocite, a type of low-grade ore that only contains about 2-3% copper. The development of copper metallurgy has gone through a long process, but even today copper is mainly smelted by pyrometallurgy, which accounts for about 80% of the world's total copper production.
Modern hydrometallurgy techniques are gradually being introduced, significantly reducing the cost of copper refining.
Copper has many valuable physical and chemical properties, such as high thermal and electrical conductivity, chemical stability, high tensile strength, good weldability, corrosion resistance, ductility and malleability.
Pure copper can be spun into very fine wires or made into very thin copper sheets. It can form alloys with zinc, tin, lead, manganese, cobalt, nickel, aluminum, iron and other metals. The alloys formed are mainly divided into three categories: brass, which is a copper-zinc alloy; bronze, which is a copper-tin alloy; and cupronickel, which is a copper-cobalt-nickel alloy.
Proportion of the main performance applications of copper and copper alloys.
Copper is a non-ferrous metal that has a close relationship with man and is widely used in the fields of electrical engineering, light industry, machinery manufacturing, construction industry, national defense industry, etc. In China, copper consumption is second only to aluminum among non-ferrous metallic materials.
According to the average annual per capita consumption: in developed countries (representing around 1.1 billion people) it is between 10-20 kg; developing countries (representing around 4.9 billion people) is between 0-2 kg.
The level of copper consumption in developed countries is significantly higher than that in developing countries. In developed countries, an average resident needs to consume about a ton of copper in their lifetime, which is a considerable number.
Comparing the two data above shows that the level of copper consumption reflects, to a certain extent, the level of development of a country. Although China's copper demand has increased significantly in recent years, there are still some poor areas in rural areas where the average annual per capita consumption is only about 0.1 kg, which is similar to that of India (0.13 kg), indicating a vast development potential.
Copper consumption structure in China:
Copper consumption structure in the United States:
From the above two numbers, we can see that there is a significant difference in the structure of copper consumption between China and the United States. The consumption of electrical and electronic products in China represents half of total consumption, while in the USA it represents 70%.
The US also has a higher consumption of copper in the construction industry, while in China the consumption of copper in construction is negligible. Compared with European and American countries, China's application of copper in construction has only begun in recent years, with a huge potential market.
According to statistics, copper use in housing in the United States increased from 120 kg per household in 1970 to 200 kg in 1996. On average, automobiles used 10 kg of copper per vehicle in 1950 and increased to 19 kg in 1996. Electric vehicles require an increase in copper usage from 25 kg to 40 kg per vehicle.
Allocation of copper usage across various construction sectors in the global copper market.
The specific allocation of copper usage across various construction sectors in the global copper market is as follows:
(1) Housing construction, including: plumbing systems (water, heat, gas, fire extinguishers, etc.); house facilities (air conditioning, refrigerators, etc.); building decoration (roofs, gutter decorations, etc.); communication lines (audio, video, data, etc.); power systems.
(2) Production of equipment, including: industrial equipment (motors, transformers, etc.); transport (cars, railways, aircraft, etc.); electronic devices; light industrial products (household appliances, instruments, tools, etc.).
(3) Basic infrastructure, including: large-scale engineering projects (transportation facilities, petrochemical industry, mining and metallurgy, etc.); electrical energy industry (transmission, distribution, etc.); communication networks. It is worth mentioning that housing construction is directly related to people's standard of living, with copper having the highest proportion of application in this area. In particular, China considers residential construction an important part of driving the development of the national economy. It appears that the active promotion of copper application plays an important role in the country's economic and social development.
Application of copper in electrical industry:
(1) Power transmission
National electricity consumption data from 1998 to 2003.
The figure above shows the electricity consumption situation in China from 1998 to 2003, with 2003 as the predicted value. The rapid increase in electricity demand driven by China's economic development requires a large amount of highly conductive copper in power transmission, mainly used in power cables, busbars, transformers, switches, connectors and interconnections. In the process of transmitting energy through wires and cables, electrical resistances generate heat and waste energy.
From the perspective of energy conservation and economics, the world is currently promoting the “optimal cable cross-section” standard. In the past, the popular standard was based solely on reducing cable cross-section to minimize the minimum allowable cable size under the design required current rating in order to reduce initial installation costs without causing dangerous overheating.
Cables installed in accordance with this standard have lower installation costs, but consume relatively more energy due to electrical resistance during long-term use. The “optimal cable cross-section” standard considers both single installation costs and power consumption, appropriately enlarging cable size for optimal energy savings and comprehensive economic benefits. According to the new standard, the cable cross-section is often more than doubled compared with the old standard, which can achieve a saving effect of about 50%.
In the past, due to insufficient supply of copper, China took the step of replacing copper with aluminum in overhead high-voltage transmission lines, considering that aluminum accounts for only 30% of the weight of copper and hoping to reduce the weight. However, from the point of view of environmental protection, overhead transmission lines will be replaced by the installation of underground cables. Under such circumstances, aluminum has disadvantages such as low conductivity and larger cables compared to copper, making it less competitive.
For the same reasons, replacing aluminum-wound transformers with copper-wound transformers, which are energy efficient, is also a wise choice.
(2) Engine manufacturing
In the manufacture of engines, copper alloys with high conductivity and strength are widely used. The main copper parts are the stator, rotor and shaft head. In large motors, the winding needs to be cooled by water or hydrogen gas, called dual water internal cooling or hydrogen-cooled motors, which require long hollow conductors.
Motors are large consumers of electricity, accounting for around 60% of all electricity supply. The cumulative electricity bill for running an engine is very high. It generally reaches the cost of the engine itself in the first 500 hours of operation and is 4 to 16 times the cost in a year. Over the entire service life, the cost can reach 200 times.
A slight improvement in engine efficiency can not only save energy but also achieve significant economic benefits. Developing and applying efficient engines is a hot topic in the world today. As the internal energy consumption of motors comes mainly from the loss of resistance of the windings, increasing the cross-sectional area of the copper wire is a fundamental measure to develop efficient motors. In recent years, some high-efficiency motors have been developed that use 25-100% more copper windings than traditional motors. The US Department of Energy is currently funding a development project that proposes the production of engine rotors using molten copper technology.
(3) Communication cables
Since the 1980s, due to the advantages of large current-carrying capacity of optical fiber cables, they have continuously replaced copper cables in communication backbones and rapidly promoted the application. However, a large amount of copper is still required to convert electrical energy into optical energy and insert user lines. With the development of the communications industry, people's dependence on communication is increasing, and the demand for fiber optic cables and copper wires will continue to increase.
(4) Residential electrical wiring
In recent years, with the improvement of people's living standards in China and the rapid popularization of household appliances, the electrical load of residential electricity has grown rapidly. As shown in Figure 6.6, in 1987, residential electricity consumption was 26.96 billion kilowatt-hours (kWh); by 1996, it had increased to 113.1 billion kWh, a 3.2-fold increase.
Despite this growth, there is still a significant gap compared to developed countries. For example, in 1995, per capita electricity consumption in the United States was 14.6 times that of China and in Japan it was 8.6 times that of China. There is still great potential for the growth of residential electricity consumption in China in the future. It is expected to increase 1.4 times between 1996 and 2005.
At present, the designed capacity of residential electrical wiring in China is relatively low. Taking a two-bedroom apartment as an example, Table 6.l compares the architectural electrical design standards in Beijing, Hong Kong and Japan. It can be seen that Hong Kong and Japan have fully considered the demand for increasing residential electricity consumption in their projects, while China's residential electrical wiring design capacity needs to be improved urgently.
Application of Copper in the Electronic Industry
The electronics industry is an emerging industry that continues to develop new copper products and new applications as it grows. Currently, its applications have evolved from electron tubes and printed circuits to microelectronics and semiconductor integrated circuits.
(1) Electron tubes
Electron tubes mainly consist of high and ultra-high frequency transmission tubes, waveguides and magnetron tubes, which require high-purity oxygen-free copper and dispersion-strengthened oxygen-free copper.
(2) Printed circuits
Copper printed circuits use copper foil as a surface, which is glued to a plastic plate as a backing. The circuit wiring diagram is printed on the copper plate by photolithography, and the excess is removed by etching to leave an interconnected circuit.
Then drill holes in the connection between the printed circuit board and the outside, insert the terminals of discrete components or other parts, and solder them into this path to complete the assembly of a complete circuit. If the dip coating method is used, all joint welds can be completed at once.
Therefore, printed circuits are widely used in situations that require precise layout of circuits, such as radios, televisions, computers, etc., saving a lot of labor in wiring and fixing circuits and requiring large consumption of copper sheets. In addition, various low-price, low-melting-point, and good-flow copper-based solder materials are also required for circuit connections.
(3) Integrated Circuits
The core of microelectronic technology is integrated circuits. An integrated circuit refers to a miniaturized circuit in which the components and interconnections that make up the circuit are integrated within, on the surface of, or above a semiconductor crystalline material substrate (chip) using specialized process technology.
This type of microcircuit is thousands or even millions of times smaller in size and weight than the most compact in structure discrete component circuit. Its emergence caused a major change in computers and became the basis of modern information technology.
Currently developed large-scale integrated circuits can produce hundreds of thousands or even millions of transistors on a single chip area smaller than a fingernail. Recently, internationally renowned computer company IBM made a breakthrough by using copper instead of aluminum as interconnects in silicon chips.
This new type of copper microchip can achieve a 30% efficiency gain, reduce circuit line sizes to 0.12 microns, and allow up to 2 million transistors to be integrated on a single chip. This opened new perspectives for the ancient copper metal in the newer technological field of semiconductor integrated circuits.
(4) Lead Frames
To protect the normal operation of integrated circuits or hybrid circuits, they need to be packaged; and during packaging, a large number of connectors in the circuit need to be removed from the seal.
These cables require a certain strength to form the supporting structure of the packaging integrated circuit, called the lead structure.
In actual production, to achieve high-speed and large-scale production, lead structures are generally continuously stamped onto a metal strip in a specific arrangement. The main structure material accounts for 1/3 to 1/4 of the total cost of the integrated circuit and is widely used; therefore, low cost is required.
Copper alloys have low prices, high strength, conductivity and thermal conductivity, excellent processing performance, weldability and corrosion resistance. Through alloying, its properties can be controlled within a wide range to better meet the performance requirements of lead structures.
Copper has become an important material for lead structures and is currently the most commonly used material for copper in microelectronic devices.
Application of Copper in the Energy and Petrochemical Industry
(1) Energy Industry
Both thermal energy and atomic energy generation rely on steam to do work. The steam circuit is as follows: the boiler generates steam – the steam drives the turbine to work – the steam after work is sent to the condenser – cooled in water – returned to the boiler to become steam again.
During this period, the main condenser is composed of tubular plates and condenser tubes. Copper is used to manufacture them due to its good thermal conductivity and resistance to water corrosion. They are all made of yellow brass, aluminum brass or white copper.
According to data, for every 10 thousand kilowatts of installed capacity, 5 tons of condenser tubes are needed. A 600,000-kilowatt power plant requires 3,000 tons of condenser tube material. Using solar energy also requires a lot of copper pipes.
For example, a hotel near London equipped with a swimming pool has a solar heater that can maintain the water temperature between 18-24°C in summer. The solar heater contains 784 pounds (356 kg) of copper tubing.
(2) Petrochemical Industry
Copper is also sometimes used in the petrochemical industry. One example is the use of copper-nickel alloys for heat exchangers in seawater-cooled nuclear power plants. The alloy has excellent resistance to corrosion from seawater and high temperatures, making it ideal for use in this application.
Copper is also used in the construction of pipelines and tanks for transporting oil and gas due to its high strength and excellent corrosion resistance.
Additionally, copper is used in catalysts for chemical reactions in refineries and other chemical plants.
(2) Petrochemical Industry
Copper and many copper alloys have good corrosion resistance in non-oxidizing acids such as aqueous solutions, hydrochloric acid, organic acids (such as acetic acid, citric acid, fatty acids, lactic acid, oxalic acid, etc.), various alkalis, except ammonia and non-oxidizing organic compounds (such as oils, phenols, alcohols, etc.).
Therefore, they are widely used in the petrochemical industry for the manufacture of various containers, pipeline systems, filters, pumps and valves for contact with corrosive media.
Copper is also used in the manufacture of various evaporators, heat exchangers and condensers due to its thermal conductivity. Due to its good plasticity, copper is particularly suitable for manufacturing heat exchangers of complex structures with intertwined copper tubes in modern chemical industries.
Additionally, bronze is used to produce tools in oil refining plants because sparks will not occur on impact, which can prevent fires from occurring.
(3) Ocean Industry
The ocean covers more than 70% of the Earth's surface and the development and rational use of marine resources is increasingly valued. Seawater contains chloride ions that can easily cause corrosion, and many engineering metal materials such as copper, iron, aluminum and even stainless copper are not resistant to seawater corrosion.
Additionally, marine biofouling can also form on the surfaces of these materials, as well as non-metallic materials such as wood and glass. Copper is unique in that it is not only resistant to seawater corrosion, but also has a bactericidal effect when copper ions dissolve in water, which can prevent marine biofouling.
Therefore, copper and copper alloys are very important materials in the ocean industry and are widely used in seawater desalination plants, offshore oil and gas platforms and other coastal and underwater installations.
For example, pipeline systems, pumps and valves used in seawater desalination processes, equipment used on oil and gas platforms including splash zones and underwater screws, drilling days, anti-fouling sleeves, pumps, valves and pipeline systems, and so on.
Application of copper in the transport industry
(1) Ships
Due to its excellent resistance to seawater corrosion, many copper alloys such as aluminum bronze, manganese bronze, aluminum brass, tin-zinc bronze), white copper and nickel-copper alloy (Monel alloy), have become standard materials for shipbuilding. Copper and copper alloys make up 2-3% of the weight of warships and most large commercial ships. The propellers on warships and most large commercial ships are made of aluminum, bronze, or brass.
The propellers on large ships weigh 20 to 25 tons each, while those on the aircraft carriers Elizabeth Queen and Mary Queen weigh up to 35 tons each. The heavy tail rods of large ships are usually made of “Admiral” metal, and the tapered screws of the rudders and propellers are also made of the same material. Copper and copper alloys are also widely used in engines and boilers. The world's first nuclear-powered merchant ship used 30 tons of white copper condenser tubes. Recently, large heating coils with brass and aluminum tubes are being used as oil tanks.
There are 12 such storage tanks on a 100,000 ton ship, and the corresponding heating system is quite large. The electrical equipment on board is also very complex, with motors, motors, communication systems, etc. depending almost entirely on copper and copper alloys to function.
Copper and copper alloys are often used for decoration in cabins of ships of all sizes, and even wooden boats are preferably fastened with copper alloy (usually silicon bronze) screws and nails, which can be mass-produced by rolling. In the past, copper plating was often used to protect the hull from marine biofouling, but now, copper-containing brush painting is commonly used.
During World War II, to prevent German magnetic mines from attacking ships, an anti-magnetic mine device was developed. A strip of copper was fixed around the copper hull and an electric current passed through it to neutralize the ship's magnetic field, which prevented the mines from detonating.
Since 1944, all Allied ships, numbering about 18,000 in total, have been equipped with this degaussing device for protection. Some large warships require a large amount of copper for this purpose. For example, one uses 28 miles (about 45 kilometers) of copper wire, weighing about 30 tons.
(2) Automobiles
Each car typically contains 10 to 21 kg of copper, depending on the type and size of the vehicle. For small cars, the amount of copper used represents 6-9% of their weight. Copper and copper alloys are mainly used in radiators, brake system piping, hydraulic devices, gears, bearings, brake pads, power and distribution systems, washers and various connectors, accessories and decorative parts.
Radiators use a relatively large amount of copper. In modern tube and strip radiators, brass strips are soldered to the radiator tubes and thin copper strips are folded into heat dissipation fins. In recent years, many improvements have been made to further improve the performance of copper radiators and increase their competitiveness with aluminum radiators.
In terms of materials, trace elements are added to copper to increase its strength and softening point without sacrificing thermal conductivity, thus reducing strip thickness and saving copper usage.
In terms of manufacturing processes, high-frequency or laser copper tube welding and copper brazing are used instead of lead-contaminated soft soldering to assemble the radiator core.
The results of these efforts are presented in Table 6.2. Compared to brazed aluminum radiators, under the same heat dissipation conditions, i.e. with the same air and coolant pressure drop, the new copper radiators are lighter and significantly smaller in size, and the Good corrosion resistance and the long service life of copper make the advantages of copper radiators more prominent.
(3) Railways
The electrification of railways requires a large amount of copper and copper alloys. More than 2 tons of specially shaped copper wire are required per kilometer of overhead wire. To increase its resistance, a small amount of copper (about 1%) or silver (about 0.5%) is often added.
In addition, train motors, rectifiers and control, braking, electrical and signaling systems depend on copper and copper alloys to function.
(4) Aircraft
Copper is also essential for aircraft operation. For example, copper materials are used for wiring, hydraulic, cooling and pneumatic systems in aircraft, aluminum bronze tubes are used for bearing seals and landing gear bearings, antimagnetic copper alloys are used for Navigation instruments and many instruments use beryllium copper. elastic elements, among other uses.
Applications of Copper in the Mechanical and Metallurgical Industries
(1) Mechanical Engineering
Copper components can be found in almost all machines. In addition to the large amount of copper used in motors, circuits, hydraulic systems, pneumatic systems, and control systems, a variety of transmission parts and fasteners made of brass and bronze, such as gears, worm gears, worm shafts, connectors, fasteners, elements twisting screws, screws, nuts, etc., are all made of copper alloys.
Almost all parts that move relative to each other in a machine require bearings or bushings made from wear-resistant copper alloys, especially the cylinder liners and slide plates of large extruders and forging presses, which are almost made of bronze. and can weigh several tons.
Many elastic elements are also made from silicon bronze and tin bronze. Welding tools, casting molds, and more rely on copper alloys.
(2) Metallurgical Equipment
The metallurgical industry is a large consumer of electricity and is known as the “electric tiger”. In the construction of a metallurgical plant, a large-scale power distribution system and power operation equipment that rely on copper must be present.
In addition, in pyrometallurgy, continuous casting technology has dominated, and the main components of the crystallizer mainly use copper alloys with high strength and high thermal conductivity, such as chromium copper and silver copper.
For electrical smelting, water-cooled crucibles for vacuum arc furnaces and electric arc furnaces are made of copper tubes, and several induction heating coils are wound with copper tubes or special-shaped copper tubes and cooled by water.
(3) Alloy additives
Copper is an important additive element in copper-iron and aluminum alloys. Adding a small amount of copper (0.2 ~ 0.5%) to low-alloy structural copper can improve its strength and resistance to atmospheric and marine corrosion.
Adding copper to corrosion-resistant cast iron and stainless copper can further improve its corrosion resistance. Alloys with a high nickel content with about 30% copper are famous for their high strength and corrosion resistance, such as the “Monel alloy”, widely used in the nuclear industry.
Many high-strength aluminum alloys also contain copper. Through quenching and aging heat treatment, fine particles are precipitated and diffusely distributed in the alloy, significantly improving its strength, known as age-hardened aluminum alloy.
The famous one is duralumin or hard aluminum, an important structural material for the manufacture of airplanes and rockets and contains copper, manganese and magnesium.
Applications of copper in light industry
Light industrial products are closely related to people's lives and have a wide variety. Due to copper's good comprehensive performance, it can be seen everywhere in light industry. Here are some examples:
(1) Air conditioning and refrigeration units
The temperature control function of air conditioners and refrigeration units is mainly achieved through evaporation and condensation of copper tubes in heat exchangers. The size and heat transfer performance of heat exchange tubes largely determine the efficiency and miniaturization of the entire air conditioning machine and refrigeration unit. Molded copper tubes of high thermal conductivity are used in these machines.
Recently, heat pipes with internal grooves and high fins have been developed and produced using the excellent processing properties of copper for use in heat exchangers for air conditioners, refrigeration units, chemical and waste heat recovery devices.
The total heat conduction coefficient of the new heat exchanger can be increased to 2 to 3 times that of ordinary tubes and 1.2 to 1.3 times that of low fin tubes, which saves 40% of copper and reduces the heat exchanger volume by more than 1/3.
(2) Watches
Most functional parts of watches, timers and watchmaking devices produced today are made from “watch brass”. The alloy contains 1.5-2% lead and has good processing properties, making it suitable for mass production.
For example, gears are cut from long bars of extruded brass and mandrels are drilled into strips of corresponding thickness. Watch faces with engraved patterns, screws and gaskets are made of brass or other copper alloys.
A large number of cheap watches are made of brass (tin-zinc bronze) or plated with nickel-silver (white copper). Some famous watches are made of copper and copper alloys. The British “Big Ben” hour hand is made from solid brass rods, and the minute hand is made from a 14-foot long copper tube.
In a modern watch factory, copper alloys are the main materials and are processed with precise presses and molds to produce 10,000 to 30,000 watches per day at low cost.
(3) Papermaking
In today's rapidly changing society, paper consumption is high. The surface of paper looks simple, but the papermaking process is very complex and requires many machines, including coolers, evaporators, beaters, paper machines and more.
Most of these components, such as various heat exchange tubes, rollers, beating bars, semi-fluid pumps and wire screens, are made of copper alloys.
For example, the currently used long-wire paper machine sprays the prepared pulp onto a movable wire screen with small mesh holes (40-60 mesh). Wire mesh is woven from brass and phosphor bronze threads and has a large width, typically greater than 6 meters (20 feet), and must be kept completely straight.
The mesh moves over a series of small brass or copper rollers, and as wet fibers with attached pulp pass through it, moisture is sucked out from underneath. The mesh also vibrates to bring together the small pulp fibers. The wire mesh size of large paper machines can reach 26 feet 8 inches wide (8.1 meters) and 100 feet (30.5 meters) long.
Wet pulp not only contains water but also corrosive chemical agents used in the papermaking process. To ensure paper quality, strict requirements are imposed on the wire mesh material, which must have high strength, elasticity and corrosion resistance, characteristics perfectly suited to copper alloys.
(4) Printing
Copper plates are used for photolithography in printing. Polished copper plates are sensitized with photosensitive emulsion and then exposed to photographic images. The sensitized copper plate needs to be heated to harden the emulsion.
To prevent softening due to heating, copper often contains a small amount of silver or arsenic to increase the softening temperature. Then the plate is etched to form a printing surface with distributed concave and convex dots.
In automatic typesetting machines, copper letter molds are used to make plate templates, another important use of copper in printing. Letter molds are usually made of leaded brass, sometimes copper or bronze.
(5) Pharmaceutical Products
In the pharmaceutical industry, various pure copper steam, boiling and vacuum devices are used. Zinc white copper is widely used in medical instruments. Copper alloys are also commonly used materials for eyeglass frames and more.
Copper for Architecture and Art
(1) Duct system
Due to its beautiful appearance, durability, easy installation, safety, fire prevention, health care and many other advantages, copper water pipes have an obvious cost-effective advantage over galvanized copper pipes and pipes. plastic. In residential and public buildings, it is increasingly preferred as the material of choice for water supply, heating, gas supply and fire extinguishing systems.
In developed countries, copper water supply systems already represent a large proportion. The Manhattan Building in New York, which claims to be the sixth tallest building in the world, uses 60,000 feet (1 km) of copper pipes just for its water supply system. In Europe, there is a large consumption of copper pipes for drinking water.
The average consumption of copper pipes for drinking water in the United Kingdom is 1.6 kg per person per year, while in Japan it is 0.2 kg. Galvanized copper pipes corrode easily and many countries have banned their use. Hong Kong has banned its use since January 1996, and Shanghai since May 1998. It is imperative that China promote the use of copper duct systems in housing construction.
(2) Home Decoration
In Europe, it is traditional to use copper plates on roofs and eaves. In Nordic countries, it is even used as wall decoration. Copper has good resistance to atmospheric corrosion, durability, recyclability, excellent workability and beautiful color, which makes it very suitable for home decoration.
Its application in ancient buildings such as churches still shines brightly today, and its use in large-scale modern buildings, even apartments and houses, is increasing. For example, in London, the Commonwealth Institute building, which represents modern British architecture, has a complex roof made of copper plates that weighs approximately 25 tons. The Crystal Palace Sports Centre, opened in 1966, has a wave-shaped roof made from 60 tonnes of copper.
According to statistics, in Germany the average consumption of copper roofing sheets is 0.8 kg per person per year, while in the United States it is 0.2 kg. In addition, the use of copper products for interior decoration, such as door handles, locks, hinges, railings, lamps, wall decorations and kitchen utensils, not only lasts long and is hygienic, but also adds an elegant atmosphere and is deeply appreciated. by people.
(3) Sculptures and Crafts
There is no metal in the world that can be as widely used to make various crafts as copper, which has lasted from ancient times to the present day. In today's urban construction, a large number of cast copper alloys are used to make monuments, bells, treasure vessels, statues, Buddhas and ancient imitations.
Modern musical instruments such as white brass flutes and brass saxophones also use copper materials. Various exquisite works of art, cheap and beautiful gold-plated jewelry or imitation gold/silver also require the use of copper alloys with different compositions.
The Tian Tan Buddha in Hong Kong, completed in 1996, is made of tin, zinc and leaded bronze, weighs 206 tonnes and is 26 meters high. The South Sea Guanyin Buddha on Putuo Mountain, Zhejiang Province, completed in 1997, is 20 meters high and weighs 70 tons. It is the world's first giant copper statue built with imitation gold materials.
After that, an 88-meter-tall bronze statue of Shakyamuni Buddha was completed in Wuxi. Taller Buddha statues are under construction on Hainan Island, Jiu Hua Mountain, India and Japan.
(4) Coins
Since our human ancestors began using coins for trade, copper and copper alloys have been used to make coins, which have been passed down from generation to generation until now. With the development of modern activities such as coin-operated automatic telephones, transportation, and shopping that benefit people, the use of copper for coin production has increased over time.
In addition to changing dimensions, different alloy compositions can be conveniently used to manufacture and distinguish coins of different denominations by changing the colors of the alloys.
Commonly used coins include “silver coins” containing 25% nickel, brass coins containing 20% zinc and 1% tin, and “copper” coins containing small amounts of tin (3%) and zinc (1.5%). %). The production of copper coins around the world consumes tens of thousands of tons of copper every year.
London's Royal Mint alone produces seven hundred million copper coins every year, requiring approximately seven thousand tons of metal.
Applications of copper in high technology
Copper not only has a wide range of applications in traditional industries, but also plays an important role in emerging industries and high-tech fields. For example:
(1) Computers
Information technology is the cutting edge of high technology. It is based on the tool of modern human wisdom, the computer, to process and deal with the vast and fast-moving sea of information. The heart of the computer consists of a microprocessor (including an arithmetic logic unit and a control unit) and memory.
These basic components (hardware) are all large-scale integrated circuits, with millions of interconnected transistors, resistors, capacitors and other devices, distributed on tiny chips to perform fast numerical calculations, logical operations and massive information storage.
These integrated circuit chips need to be assembled using lead frames and printed circuits to function.
As mentioned in the previous chapter “Applications in the Electronics Industry”, copper and copper alloys are not only important materials for lead structures, solders and printed circuit boards, but also play an important role in interconnecting the tiny components of integrated circuits .
(2) Superconductivity and Low Temperature
For most materials (except semiconductors), their electrical resistance decreases as the temperature decreases. When the temperature drops to a very low level, the resistance of certain materials can disappear completely, which is called superconductivity.
The maximum temperature at which superconductivity appears is called the critical temperature of the material. The discovery of superconductivity opened a new frontier in the use of electricity.
With zero electrical resistance, a very large (theoretically infinite) current can be generated with a very small voltage, generating enormous magnetic fields and forces, or there is no decrease in voltage or loss of energy when the current passes through it. Obviously, its practical applications will bring changes to production and human life and have attracted a lot of attention.
However, for common metals, superconductivity only appears when the temperature approaches absolute zero (0K = -273°C), which is difficult to achieve in engineering practice. In recent years, some superconducting alloys have been developed with higher critical temperatures than pure metals.
For example, the Nb3Sn alloy has a critical temperature of 18.1K. However, its application still relies heavily on copper. First, these alloys must work at ultra-low temperatures, which are achieved by liquefaction of gases such as liquid helium, hydrogen and nitrogen, with liquefaction temperatures of 4K (-269°C), 20K (-253°C) and 77K. (-196°C), respectively.
Copper still exhibits good ductility and plasticity at such low temperatures, making it an essential material for structural and pipeline transportation in low-temperature engineering.
Furthermore, superconducting alloys such as Nb3Sn and NbTi are brittle and difficult to process into molded materials, requiring copper as a cladding material to bond them together.
Currently, these superconducting materials have been used to create strong magnets in medical diagnostic devices such as MRIs and powerful magnetic separators in some mines. Planned maglev trains with speeds exceeding 500 km/h also rely on these superconducting materials to suspend the train and avoid wheel-rail contact resistance, achieving high-speed operation of the cars.
Recently, some high-temperature superconducting materials have been discovered, most of which are compound oxides.
One of the first and best known is lead-containing copper-based oxide (YBa2Cu3O7), with a critical temperature of 90K, which can operate at liquid nitrogen temperatures. Currently, materials with critical temperatures close to room temperature have not yet been developed, and these materials are difficult to form into large blocks, and their current density that maintains superconductivity is not high enough for use in high-electricity applications. Therefore, more research and development is needed.
(3) Space Technology
In rockets, satellites and space shuttles, many critical components also require the use of copper and copper alloys, as well as microelectronic control systems and instrumentation equipment.
For example, the inner lining of the combustion chamber and thrust chamber of a rocket engine can use the excellent thermal conductivity of copper for cooling and maintain temperatures within allowable ranges.
The inner skin of the Ariane 5 rocket engine uses a copper-silver alloy to process 360 cooling channels that are cooled with liquid hydrogen during rocket launch. Additionally, copper alloys are also standard materials used for load-bearing components in satellite structures. Satellite solar panels are generally made from copper alloys containing several other elements.
(4) High Energy Physics
Revealing the mystery of the structure of matter is an important basic scientific problem that scientists are striving for. Each step towards understanding this issue will have significant impacts on humanity. The current use of atomic energy is an example of this.
The latest research in modern physics has discovered that the smallest units of matter are not molecules and atoms, but quarks and leptons that are billions of times smaller. Research into these fundamental particles often requires high energies hundreds of times greater than the nuclear effects at the time of atomic bomb explosions, known as high-energy physics.
This high energy is obtained by charged particles accelerating long distances in a strong magnetic field, “bombarding” a fixed target (high-energy accelerator), or by the collision of two streams of particles accelerating in opposite directions (collider).
To do this, copper is used to build a long-distance strong magnetic field channel like a winding structure. Furthermore, similar structures are required in controlled thermonuclear reaction devices. To reduce heat generation caused by the passage of large currents, these magnetic channels are wrapped around hollow copper rods to allow refrigerant to enter.
For example, the water-cooled magnet of the famous synchrotron proton accelerator at the European Particle Physics Laboratory (CERN) is composed of around 300 tons of extruded copper material rolled into hollow copper tubes.
The heavy ion accelerator built in China in 1984 used a total of 46 tons of tube material, each with a length of 40 meters, outer diameter and inner circle. Copper tubes weighing 105 tons were used in the later built positron-electron collider.
In the controlled thermonuclear reaction device developed in China, there are a total of 16 focusing coils, each of which is wrapped with a 55-meter-long copper rod. The housing is welded from copper plates, with cooling water tubes welded to them. A total of 50 tons of copper were used in this device.
Applications of Copper Compounds
Copper compounds include copper sulfate (pentahydrate, monohydrate and anhydrous), copper acetate, copper oxide and cuprous oxide, copper chloride and cuprous chloride, copper oxychloride, copper nitrate, copper cyanide, salts of copper fatty acids, cyclohexane copper carboxylates, etc.
They have wide applications in agriculture, industry, medicine, healthcare and other fields. Among them, copper sulfate is the most used and is generally copper sulfate pentahydrate (CuSO4·5H2O), commonly known as blue vitriol due to its blue color. It is often used as a raw material for the production of many other salts.
The history of human use of copper compounds dates back to more than 5,000 years ago, when the ancient Egyptians discovered that copper sulfate was a good mordant (dyeing agent) for coloring.
According to statistics, there are currently more than a hundred factories that produce copper sulfate around the world, with an annual consumption of around 200,000 tons, of which three quarters are used in agriculture and livestock farming as a fungicide.
Applications of Copper Compounds in Agriculture and Livestock
Copper compounds are effective fungicides that can control all diseases caused by mold or fungi. In addition to directly soaking seeds with copper sulfate, various copper salt mixtures are commonly used in orchards and fields.
The most important are the Bordeaux mixture (mixture of copper sulfate and lime) named after the famous French wine region and the Burgundy mixture (mixture of copper sulfate and soda), as well as Paris green and Cuprokill, etc.
According to reports, copper fungicides can prevent more than 300 types of diseases that frequently occur in more than a hundred crops. These crops include various evergreen fruit trees such as grapes, oranges, bananas, apples, pears, peaches, etc.; Economic crops such as coffee, rubber, cotton, sugar beet, etc.; Cereals such as wheat, rice, corn, barley, oats, etc.; Beans, tomatoes, potatoes, lettuce and so on.
Copper is also a necessary nutrient to maintain the healthy growth of crops and livestock. Generally, when the available copper content in farmland soil is less than 2 ppmm (1 ppmm is one percent), crops will suffer from copper deficiency and reduce yield, or even stop growing. Similarly, when the available copper content in pasture soil is less than 5 ppm, livestock will suffer from copper deficiency disease.
Currently, due to intensive high-yield operations, the widespread use of fertilizers containing little or no copper has led to land degradation and the growing problem of copper deficiency throughout the world.
To correct and prevent copper deficiency, copper salts must be supplemented in a timely manner. They can be added directly or mixed with fertilizers rich in nitrogen and phosphorus, applied to improve soil quality for long-term effect, or sprayed on crop seedlings every year. For livestock, in addition to improving pastures, copper salts can be mixed into feed or injected directly into livestock showing symptoms of copper deficiency.
Copper sulfate is also a growth promoter in pigs and chickens, which can improve appetite and promote feed conversion. Mixing 0.1% copper sulfate into feed can significantly promote weight gain in pigs and broilers. Copper ions have strong disinfecting and sterilizing effects and can prevent the spread of some common diseases in livestock.
For example, a small amount of copper in water (less than lppm) can kill snails, including those that host the blood fluke parasite, thus preventing liver fluke disease that is easily prevalent in tropical and temperate animals. Copper sulfate can also be used to disinfect pens to prevent the spread of foot rot in cattle and sheep, as well as swine erysipelas and bovine dysentery.
Additionally, copper salts can be added to eliminate irritating green algae contamination in ponds, rice fields, canals and rivers. Copper salts can also be used as mold inhibitors and preservatives for storing grains, fruits and vegetables. A convenient method is to wrap them with paper soaked in copper salt.
Applications of Copper Compounds in Industry
Copper compounds have wide applications in industry and are used more or less in almost every field. here are some examples:
Copper sulfate is a mordant commonly used in dyeing processes to improve the durability and wash resistance of gloss, and is widely used in the textile and leather industries. Copper compounds have colors such as blue, green, red, black, etc., and can be used as colorants for glass, ceramics, cement and enamel. They are also components of certain hair dyes.
Copper nitrate added to fireworks produces green light, etc. Paints with added copper compounds have anti-marine biofouling properties. Some organic copper compounds are effective preservatives used to prevent corrosion in cellulose, wood, wood products, canvas and other fabrics.
Certain copper compounds are important chemical agents in the production of rubber, petroleum and synthetic fibers, playing roles in catalysis and purification.
Copper sulfate electrolyte is used for copper plating, electrolytic copper foil production and copper purification.
In the mining industry, copper sulfate is used as an activator for the flotation of minerals such as lead, zinc, aluminum and gold.
Applications of copper compounds in human health
Copper is an essential nutrient for human health, important for the blood, central nervous and immune systems, development and function of hair, skin and bone tissue, as well as internal organs such as the brain, liver and heart.
Copper is mainly ingested through the daily diet. The World Health Organization recommends that adults consume 0.03 milligrams of copper per kilogram of body weight per day to maintain health.
Pregnant women and young children should double the amount. Copper deficiency can cause several illnesses, and copper supplements and pills can be taken to supplement it. Copper ions can disinfect and sterilize and are useful for disease prevention and hygiene.
For example, they can kill bacteria such as E. coli and dysentery in water, eliminate snails and slugs that spread schistosomiasis, and mosquito larvae that spread malaria.
They can also be used in swimming pools to prevent contamination by green algae and the spread of athlete's foot along the floor, etc. Copper compounds can be used to treat certain diseases. It is known that wearing a copper ring can treat arthritis.
Copper sulfates have been used to treat lung and mental illnesses in some Western countries, while in some African and Asian countries they have been used to treat ulcers and skin diseases. Currently, copper-containing drugs are being developed.
