The origins of copper
What is copper?
Where can you find copper?
Copper is a natural element found in the earth’s crust, lakes, oceans and rivers. In most cases, copper is found in mines that contain 0.2-0.8% of the metal, much less often in the original state rather than copper nuggets.
History of copper
When did humans discover copper?
Archaeological evidence shows that copper was one of the first metals humans used to make objects such as coins and ornaments in Western Asia at least 10,000 years ago. The first signs of copper refining activity for the manufacture of objects date from around 5000 BC. Subsequently, copper was used in advanced water systems, with examples dating as far back as 2750 BC. In Europe, the discovery of the Similaun man, also known as Ötzi, in the Alps with an ax with a point made of 99.7% pure copper confirmed the use of copper around 3200 BC. Chr.
What was copper used for in early human history?
As a ductile and durable material, copper was primarily used to make tools for everyday use. During the prehistoric Chalcolithic period (derived from Chalcus, the Greek word for copper), man discovered how to extract and use copper to make ornaments and tools. In the time of the Egyptians, copper was used to treat infections and sterilize water.
Process for the extraction and processing of copper
In which countries is copper mined?
The most important copper mines are located along the Andes and the Rocky Mountains: The most important countries for copper mining are Chile, Peru, China, the United States, the Congo and Australia. Other important mines can be found in Indonesia, Papua New Guinea, Zambia, Canada, countries of the former USSR, Poland and Finland.
Which methods are used for mining?
There are three main methods of copper mining:
• Extraction from open-cast or underground mines: The extracted material is crushed and ground; the sludge obtained is dried and subjected to a concentration, roasting and melting process up to thermal or electrolytic refining.
• Leaching: The pouring of water and sulfuric acid solution on the mineral and then processing the material obtained by electrolysis. This process is increasingly used because it also enables the treatment of minerals with a very low copper content, but also because it is more sustainable: it requires less energy, does not release any gases into the atmosphere and also enables small quantities to be processed.
• Recycling or secondary copper production: Copper can be reworked indefinitely without losing its properties. Around 50% of the copper used in Europe comes from recycling.
What copper reserves are there on earth?
According to the United States Geological Survey (USGS), copper reserves currently amount to approximately 870 million tons (Mt). The identified copper resources and the undiscovered copper resources are estimated at around 2,100 million t and 3,500 million t, respectively. The countries of the European Union have a total of 962,000 tons of copper reserves. Current and future exploration opportunities will increase both reserves and known holdings.
How is copper ore processed into an end product?
After mining, the copper is crushed and ground. A flotation process is then carried out to separate the metal-containing components from the accompanying rock. This is followed by the melting process, which is sometimes preceded by a roasting phase in order to obtain the so-called blister copper with a copper content of 98.5-99.5%. The next step is to refine the bladder copper and cast it into anodes for electrorefining. The result of electrorefining is a refined copper cathodes with a copper content of more than 99.99%. Copper cathodes can also be obtained by leaching or electrolytic extraction (SX-EW). Finally, copper can also be obtained from the recycling of metals that arise in the manufacture of semi-finished or finished products or disused end-of-life products.
The properties of copper
What are the main characteristics of copper?
Copper is a hardbut easy to process material, extremely ductile and malleable. These properties make it ideal for tube forming, wire drawing, rolling and deep drawing. It also has excellent thermal and electrical conductivity, which is only surpassed by silver (the conductivity of copper is 97% silver). Copper resists corrosion from fresh water and steam, salt solutions, soils, non-oxidizing minerals, organic acids and alkalis. The corrosion resistance of copper alloys is based on the formation of adhesive layers on the material’s surface, impenetrable layers that protect the base metal from further attack. It is also resistant to very high or very low temperatures and is non-magnetic.
What are the benefits of copper?
The chemical, physical and aesthetic properties of copper make it perfect for use in the home environment, in the industrial sector, and to develop new innovative and technological materials. In conjunction with other metals, it develops ideal properties for highly specialized applications, from transporting electricity and water to our homes to contributing to the development of sustainable mobility. Apart from its mechanical functions, copper is essential for the health of humans, animals and vegetation. In addition, its antibacterial properties reduce the risk of developing nosocomial infections by 58% and eliminate the pathogenic germs that settle on surfaces. This property makes it an ideal material for making objects such as handles, faucets, handrails, panels and switches that are touched more frequently and can be carriers for infection. Thanks to its high conductivity for heat and electricity, copper contributes to the energy efficiency of buildings and the reduction of greenhouse gas emissions. Copper is also an easily recyclable metal: it is estimated that 80% of the metal extracted since ancient times is still used in various forms today. This reduces the exploitation of the world’s natural resources and the waste generated in industrial processes. After all, copper is a durable and resilient material: objects made of copper can withstand pressure, extreme temperatures and wear and tear, and their lifespan can even exceed a century.
Copper alloys
What is an alloy, and how is it made?
An alloy is a combination of two or more elements, at least one of which is a metal. The resulting material has metallic properties that are different from those of its components.
What are copper alloys?
There are over 400 commonly used copper alloys, each with a unique combination of properties that serve multiple applications.
Which are the most important alloys?
• Brass alloys: made from copper and zinc with various properties,including strength, workability, ductility, wear resistance, hardness, color, electrical and thermal conductivity, and corrosion resistance.
• Bronze alloys: made of copper and tin, which were first developed about 4,000 years ago.
• Copper-nickel alloys: stronger and more resistant to marine corrosion and biofouling.
• Nickel-silver alloys (Alapacca): combine copper, nickel and zinc and are sometimes considered unique brass. They are characterized by a color tending towards silver and are used to make coins and ornaments.
• Special alloys (STOL alloys): are widely used in the automotive, IT and industrial automation sectors.
Applications
Which industries use copper and what for?
- Electricity: The very high electrical conductivity, extraordinary durability, ductility, sliding ability and corrosion resistance of copper make it the safest conductor for the cabling of commercial and residential buildings.
- Electronics and telecommunications: In HDSL and ADSL technologies, copper enables high-speed data transmission. Copper heat sinks help draw heat away from the transistors and keep the processors running at maximum efficiency. Copper is also widely used in other electronic devices in the form of wires, transformers, connectors, and switches.
- Construction: Due to their high resistance to extreme climatic conditions, copper and brass are the ideal materials for the construction of hydraulic systems, both for external lines and for interior fittings, as well as for roofing buildings. In addition, the antimicrobial and antipathogenic properties that can naturally ensure the disinfection of surfaces make it an ideal material for making contact surfaces such as handles.
- Machinery and industrial equipment: Copper alloys are ideal for products such as gears, bearings, and turbine blades because of their durability, ductility, and malleability. High heat transfer capabilities and resistance to extreme environments make copper an ideal choice for heaters, pressure vessels and tanks. Due to the corrosion-resistant properties of copper and its alloys, they are particularly suitable for use in marine environments, e.g. B. for the manufacture of ships, tanks and pipes that are exposed to seawater, propellers, oil platforms and coastal power plants.
- Transport: Almost all means of transport rely on copper in order to carry out essential functions. Copper-nickel alloys are used on the hulls of boats and ships to reduce marine pollution, thereby reducing drag and improving fuel economy. In cars and trucks, copper is used in engines, cabling systems, coolers, connectors, brakes and bearings. The average internal combustion engine today contains around 22.5 kg of copper. After all, copper is widespread in next-generation aircraft and trains: the new high-speed trains contain 2 to 4 tons of copper, twice as much as conventional electric trains.
- Coins: Copper has always played a vital role in the coin industry. Copper and its alloys are suitable for producing coins due to their coinability, exceptional abrasion and impact resistance. Copper's resistance to corrosion is well known, but copper is also favoured due to its antimicrobial properties.
What are the best-known examples of the use of copper?
Environment and sustainability
Can you recycle copper?
Copper is 100% recyclable. Copper can be recycled from both end-of-life products and processing waste. Almost 1/3 of the world’s copper needs are met by recycling each year, and an estimated 80% of the copper extracted since ancient times is still used today. Copper products contain an average of 35% recycled content, which significantly reduces the ecological footprint of copper. Although Italy does not have any copper mines, it is Europe’s highest copper inventory, thanks to its recycling and reuse capabilities.
How durable is copper?
Thanks to its full recyclability, copper has an infinite service life. Unlike most metals currently in use, it retains all of its original properties regardless of how many times it has been recycled, used or the form: Recycled copper is the same as primary copper extracted from mines.
What is the carbon footprint of copper?
By recycling copper, 900,000 tons of CO2 are saved annually for the otherwise necessary metal extraction and refining processes. According to a life cycle analysis carried out by the European copper industry on the life cycle of the most important phases, around 50% of emissions can attribute to these processes. Recycling promotes lower consumption of natural resources, lower energy consumption (up to 85 million TWh of electricity, which corresponds to the consumption of 24 million households per year) and a reduction in CO2 emissions (up to 30 million tons less per year). Further technological and innovative developments in end-of-life copper recovery and recycling at the industrial level will further reduce the carbon footprint of copper.
Is copper harmful to the environment?
Copper is an essential element for the environment and living beings. The forms, distribution, transport and possible uptake of copper by organisms, and the effects on water, sediments and soils, depend largely on the chemical and physical properties of the local environment, as well as on the various forms of each organism. Many organisms have developed physiological or metabolic means to regulate and break down any excess internal copper and other essential elements.
Can copper be found in groundwater?
Copper and brass are the best materials for plumbing applications, both at the infrastructure and household level. Unlike plastic applications, copper does not burn or melt and does not release harmful or toxic fumes in the event of a fire and can withstand both high and rigid temperatures and pressure. Copper pipes also protect water systems from life-threatening bacteria such as legionella. When intervening to disinfect the systems, copper can withstand the high temperatures required to eliminate bacteria (approx. 60 ° C), even over long periods of time. In addition, when copper comes into contact with water, it can only release copper ions that are useful for the proper functioning of human metabolism and does not contain any additives, dyes or volatile organic compounds that can alter the fluid.
Copper and the human body
Is copper dangerous for the human body?
Copper is essential for good health. It is a valuable element for children’s growth, bone strength, red and white blood cell formation, cholesterol and glucose metabolism, heart muscle contraction, brain development and very important for pregnant women.
Do people need copper in their diet?
Copper is a necessary element for the health of all life forms and is found in most food and water. Daily copper needs have been determined by various health institutions around the world. According to the World Health Organization, copper deficiency can cause health problems such as anemia, heart and circulatory problems, bone demineralization, complications in the functioning of the nervous and immune systems, lungs, thyroid, pancreas and kidneys.
What about copper in drinking water?
Copper pipes are ideal for carrying drinking water because they are reliable, safe, and help protect water systems from potentially deadly bacteria such as legionella. In addition, when copper comes into contact with water, it can only release copper ions that benefit the proper functioning of human metabolism.
Copper oxidation
Why does the appearance of copper change over time?
When copper is exposed to air and water, it combines with the oxygen it contains and forms a tough surface layer of copper oxide. This copper connection is strong and well anchored in the underlying metal and is therefore protected. This process is known as “positive corrosion”, also known as “passivation”.
How is a patina created?
Copper combines with oxygen and other elements contained in the environment, creating compounds with variable stoichiometry. The surface layer also changes depending on the type of environment it comes into contact with over time (external or internal, maritime or rural or industrial), and this is clearly visible in architecture.For example, in the creation of oxide a copper roof becomes darker over time. Over the years, it develops into a salt that is also made up of other elements and tends to be green or green-blue in color. This green protective surface is the so-called “patina”.
Cleaning and color
How can I get the original copper color? / Which products should be used to clean copper?
Copper can be cleaned with common commercially available products. Specific metal cleaning products can be used to maintain the color.
Price and lifetime of copper
How much does copper cost?
To find out the exact price of copper per kg, one must contact the London Metal Exchange (LME), the primary exchange market for non-ferrous metals, and the International Copper Study Group. The price for copper scrap is now € 4 – € 6 per kg and has remained almost unchanged compared to 2017. The price of copper scrap falls depending on the condition of the material, and the value varies depending on oxidation, size, and purity.
How long is the lifespan of an object made of copper?
The lifespan of a copper object may be infinite. Recycled copper has the same chemical, physical and technological properties as primary copper and is therefore not subject to any restrictions on use or depreciation. Currently, almost half of the copper used in Europe comes from recycling. This percentage should increase because scrap availability is closely related to consumption over a 20 to 30 year period, which is growing constantly.
Antimicrobial properties
What is antimicrobial copper?
Antimicrobial copper neutralizes harmful microorganisms such as bacteria, viruses, fungi and mold and inhibits their growth. In the last few decades, many scientific studies have confirmed these properties and copper is now frequently used in different settings, including hospitals or private households.
Is it any different from ordinary copper?
Copper has natural antibacterial and antiviral properties, and all copper has these properties. An alloy with 60% or more copper has good antibacterial and antiviral effects.
How can copper neutralize germs?
Research into the antimicrobial properties of copper metal surfaces is relatively new. Still some general principles have already been established: a higher copper content in the alloys, a higher temperature, and a higher relative humidity increases the effectiveness of copper in contact with bacteria. Surface treatments to reduce corrosion rates, such as the use of corrosion inhibitors or a thick layer of copper oxide, reduces the antimicrobial effectiveness of copper surfaces. In addition, several factors have been identified that contribute to the neutralization of bacteria, including the loss of potassium or glutamate by the bacterium’s outer membrane, disturbance of the osmotic balance, binding to proteins that do not require copper ions, and oxidative stress from the production of hydrogen peroxide. According to current knowledge, contact neutralization occurs in several stages: membrane damage, the copper influx into cells, oxidative damage, cell death and DNA degradation. How dirt, cleaning, contact with chemicals and fittings affect the antimicrobial properties of copper has not yet been investigated in detail.
Is it a dangerous process for humans?
Absolutely not, on the contrary. Copper is a necessary element for our metabolism and must also be included in our diet. Thanks to their antibacterial and antiviral properties, copper and its alloys reduce the number of pathogens and the resulting risk of infection for humans.
Which germs are eliminated by copper?
The scientific literature confirms that copper can eliminate or inactivate various types of bacteria, fungi and viruses. Notable ones include E. Coli bacteria, influenza, MRSA (Methicillin Resistant Staphylococcus, Rotavirus, Salmonella, Campylobacter, Legionella, and Coronavirus (including SARS-CoV2).
What is the difference between copper and silver?
Silver has a lower antibacterial effect than copper. Under certain conditions artificially simulated, in the laboratory (constant temperature at 37 ° C, relative humidity at 90% and plastic pressed onto the surface to be tested), surfaces coated with silver show a remarkable antibacterial effect and release thanks to the excessive humidity, which favors the exchange reactions of ions that are necessary to combat microorganisms. However, these properties are not comparable to those of copper and its alloys. In fact, scientific studies have shown that these silver coatings no longer have antibacterial properties as soon as the temperature and humidity inside a building drop to typical values.
What is the difference between copper and steel or plastic?
Comparative studies carried out on copper, aluminum, stainless steel, PVC and polyethylene have shown that copper neutralizes germs quickly and effectively, while the other materials do not display any antimicrobial properties. On the contrary, numerous international studies have scientifically proven that viruses and bacteria, including SARS-CoV2, can survive on stainless steel or plastic for days or even weeks. This phenomenon is particularly evident on damaged surfaces with grooves or cracks, where germs can survive even after disinfection. Copper, on the other hand, due to its natural properties, has a permanent neutralizing effect against germs on its entire surface, which takes place in a short period of time.
What is the influence of oxidation?
It is a natural process, the most direct evidence of which is the color change. In fact, copper and its alloys naturally oxidize and darken. This process does not affect the properties of copper and its alloys.
Does oxidation change the antimicrobial properties?
Oxidation does not limit, change or prevent the antibacterial effects of copper. In fact, some scientific studies show that oxidized surfaces of copper, bronze, and brass can be even more effective at eliminating bacteria.
Application of antimicrobial products
What antimicrobial products are there?
There are hundreds of products made of copper and copper alloys such as brass and bronze with antibacterial properties for frequent contact surfaces such as handles, railings, tables, fittings, etc. A variety of pathogens, harmful germs, viruses, bacteria, etc. can accumulate on these surfaces and survive for a very long time (even 30 days for some materials). When the surfaces are made from antimicrobial copper, these microorganisms are naturally removed between 10 minutes to less than two hours.
Do these products need special treatment?
The antibacterial properties are naturally given to copper and its alloys. If these properties are to be retained, copper objects (or objects made of copper alloys) must not be treated with wax, lacquer, paint or other coatings. Coatings and / or surface treatments would impair the valuable properties of the metal.
How long does the antimicrobial effect last?
Laboratory tests have shown that regular cleaning of copper and copper alloy surfaces removes more than 99.9% of the following microorganisms within two hours of exposure: MRSA, Enterococcus VRE, Staphylococcus aureus, Enterobacter aerogenes, Pseudomonas aeruginosa and E. coli strain O157: H7. The Institute of Virology at the University of Pisa has proven that the viral load of SARS-CoV2 on copper surfaces is reduced by 90% in 10 minutes and 100% neutralized in 60 minutes. This property also applies to copper alloys, where the viral load is reduced by 85% after 10 minutes and 100% after 60 minutes.
In any case, the antimicrobial effect of copper sets in immediately as it is a naturally antibacterial and antiviral element.
Do copper elements require special handling?
Copper and copper alloy products are self-disinfecting. However, routine cleaning is recommended to avoid the build-up of dirt: hygiene practices mandate cleaning as a “first line of defense”.
How should these elements be purified?
Standard commercially available detergents can be used to clean copper.
The benefits of antimicrobial copper
Can copper help reduce water pollution?
Copper tubing inhibits the spread of Legionella pneumophila bacteria responsible for a severe form of pneumonia that can be fatal. Scientific research has shown that, unlike polyethylene, PVC and stainless steel, copper is the only pipe material with antibacterial properties. In some recently built hospitals, copper pipes have been selected for the drinking water circuits to prevent legionella. This is the case with the Policlinico of the Biomedical Campus of Rome Trigoria and the Mother and Child Department of the S. Raffaele Hospital in Milan.
Can copper reduce food contamination?
Contact surfaces in copper and copper alloys can reduce contamination of dangerous food pathogens such as E. coli (strain O157: H7), Campylobacter jejuni, Listeria monocytogenes, Salmonella enteriditis and MRSA. Copper can quickly remove these germs in a cooled environment (4 ° C) and at room temperature (20 ° C).
Can copper reduce nosocomial infections in hospitals?
The transmission of infections is a critical issue in hospital hygiene: Nosocomial infections cause up to 100,000 deaths per year in the EU. Numerous scientific international studies have shown that viruses and bacteria, including SARS-CoV2, can survive on stainless steel or plastic for days or even weeks. On the other hand, copper has a permanent germ-neutralizing effect due to its intrinsic properties, which takes place in a short time. Studies carried out in some hospitals have shown that the surfaces of objects made of copper or copper alloys have, on average, 80% less germ load than equivalent objects made of other materials. In particular, the results of the research carried out by Sally Oaks Hospital, Birmingham, showed a 90% reduction in germs. The study found that intensive care units in three US hospitals showed a decrease in germs of 83%.
Could copper reduce the transmission of surface infections?
Copper and copper alloys have a natural antimicrobial effect. This means that they have the property of inactivating or eliminating bacteria and viruses, mold and fungi. Because of this ability, copper and its alloys can reduce communicable infections through the contact surfaces, provided the surfaces are left untreated and uncoated.
