Copper price, occurrence, extraction and use

Copper (Latin Cuprum) is a chemical element with the element symbol Cu and the atomic number 29. It is a transition metal, in the periodic table it is in the 4. Period and the 1. Subgroup (after new count group 11) or copper group. The Latin name cuprum is derived from (aes) cyprium "ore from the Greek island of Cyprus", in which copper was extracted in ancient times.

As a relatively soft metal, copper is easy to shape and tough. As an excellent heat and electricity conductor, it finds versatile use. In addition, it also belongs to the group of coin metals.

As a weakly reactive heavy metal, copper is one of the semi-precious metals.

History

Copper, gold, silver and tin were the first metals that humanity got to know in their development. Since copper is easy to process, it was already used by the oldest known crops about 10.000 years ago. The time of his long-term use of the 5. Millennium BC To the 3. Millennium BC Depending on the region, BC is also called the Copper Age. Hujayrat al-Ghuzlan in Jordan already had 4.000 v. Chr. A mass production of copper. In alchemy, copper was associated with Venus / Femininity ♀ (planetary metals) and considered to be a compound of sulfur and mercury. The first mirrors were made of this metal. During the late Eastern Mediterranean Bronze Age, copper was mainly mined on Cyprus and exported from there mostly in about 30 kg heavy copper bars in the form of bovine skins (so-called ox hide bars). Fragments of Cypriot ox-hide ingots from the time between the 16. and the 11. Century BC Chr. Are found in large parts of the Mediterranean, as far as Sardinia, in the Balkans and even north of the Alps (Depot Fund of Oberwilflingen). The largest pre-industrial copper producer was the Roman Empire with an estimated annual production of 15.000 t.

Later, copper was alloyed with tin and lead components to bronze. This harder and more technically resistant alloy became the name of the Bronze Age. The distinction between lead and tin was only introduced with growing metal knowledge, so that the term bronze is from today's perspective, only applied to the high copper tin-copper alloys properly.

The golden yellow copper-zinc alloy "brass" was already known in ancient Greece. It was melted by co-processing of the respective ores, but only the Romans used this procedure intensively. In ancient Colombia, the gold-copper alloy Tumbaga was frequently used.

occurrence

Copper is found in the earth's crust with a content of about 0,006% and is therefore in relation to the frequency of elements in the earth's crust on the 23. Location. Often, copper appears solid, that is, in elemental form. Currently (2017) 3000 is known worldwide for solid copper, including in Afghanistan, Argentina, Australia, Belgium, Bolivia, Brazil, Bulgaria, Chile, China, the Democratic Republic of the Congo, Germany, Finland, France, Greece, India, Iran, Ireland, Italy, Japan, Canada, Kazakhstan, Morocco, Mexico, Mongolia, Namibia, New Zealand, Norway, Austria, Peru, the Philippines, Poland, Portugal, Romania, Russia, Zambia, Sweden, Switzerland , Zimbabwe, Slovakia, Spain, South Africa, the Czech Republic, Turkey, Ukraine, Hungary, the United States of America (USA) and the United Kingdom (UK).

In several rock samples from the Mid-Atlantic Ridge and the Moon, which brought the probe of the Luna 24 mission of Mare Crisium, dignified copper could be detected.

Copper as a mineral

Natural deposits of solid copper, that is, in its elemental form, were known well before the founding of the International Mineralogical Association (IMA). Copper is therefore recognized as a so-called grandfathered mineral as an independent mineral species.

According to the classification of minerals according to Strunz (9 edition) copper under the system no. "1.AA.05" (Elements - Metals and Intermetallic Compounds - Copper Cupalite Family - Copper Group) respectively in the obsolete 8. Edition listed under I / A.01 (copper series). The classification of minerals according to Dana, which is predominantly used in English-speaking countries, leads the element mineral under the system no. 01.01.01.03 (Gold Group).

In nature, copper usually forms in basaltic lavas, either in the form of "copper-red", shiny metallic nuggets (solidified from the melt) or in branched structures, so-called dendrites. Occasionally, crystalline training can be found. Copper occurs in paragenesis with various, mostly secondary, copper minerals such as bornite, chalcocite, cornwallite, cuprit, azurite and malachite as well as tenorite, but may also be associated with many other minerals such as calcite, clinoclas, prehnite, pumpellyite, quartz and silver.

Copper ores are common. For example, copper is made from chalcopyrite (chalcopyrite, CuFeS2), chalcocite (chalcocite, Cu2S), more rarely from bornite (copper chalcopyrite, Cu5FeS4), atacamite (CuCl2 · Cu (OH) 2), malachite (Cu2 [(OH) 2 | CO3] ) and other ores. In 2019 636 copper minerals were known. The minerals with the highest copper concentration in the compound are cuprite (up to 88,8%) and algodonite (up to 83,6%) as well as paramelaconite, tenorite and chalcocite (up to 79,9%).

Funding

The most important copper producer is Chile, followed by Peru and the USA by a long way. In Europe, Poland, Portugal and Sweden are noteworthy. The main exporters were organized from 1967 to 1988 at CIPEC. The CIPEC included Chile, Peru and Papua New Guinea, on whose island Bougainville one of the world's largest copper mines 1988 led to a civil war.

Historically significant were the copper mines on the Keweenaw Peninsula in the Upper Lake (USA). There was the world's largest deposit of solid copper. Degradation took place there already in pre-Columbian times. In Germany, copper slate was mined in the Mansfelder Land until 1990, and in Cornwall it is mainly in the 18. and 19. Century given significant copper mining.

Recovery

Copper extraction after the levitation melting process
Various procedures

Promotion and reserves of the largest copper producing countries
In thousands of tons (2017)

Rank	Country	Funding (2017)	reserves (2017)	reserve base (2009)
1.	Chile	5.330	170.000	360.000
2.	Peru	2.390	81.000	120.000
3.	People's Republic of China	1.860	27.000	63.000
4.	United States	1.270	45.000	70.000
5.	Australia	920	88.000	88.000
6.	DR Kongo	850	20.000	k. A.
7.	Mexico	755	46.000	50.000
7.	Zambia	755	20.000	35.000
9.	Indonesia	650	26.000	38.000
10.	Canada	620	11.000	20.000
	Other countries	4.300	260.000	110.000
	Welt	19.700	790.000	1.000.000

 

The most important furnaces for copper production are the flame furnace and, since 1980, the flash smelting furnace.
Process of copper extraction

For the production of copper, so-called copper stone (Cu2S with varying contents of FeS, Cu content approx. 2%) is first obtained from chalcopyrite (CuFeS70). For this purpose, the starting material is roasted with the addition of coke and the contained iron oxides slagged by siliceous aggregates. This iron silicate slag floats on the matte and can be easily poured off.

Röstarbeit:

Melting work:

The copper matte thus obtained is further processed into crude copper (also black copper). For this purpose, it is poured into a converter with a liquid glow and air is blown into this melt. In a first stage (slag blowing) while the iron sulfide contained therein is roasted to iron oxide and this bound by slammed quartz to the slag, which can be poured off. In a second step (Garblasen) two thirds of the remaining Cu2S are oxidized to Cu2O. The oxide then reacts with the remaining sulfide to form crude copper.

Slag bubbles:

Garblasen:

The crude copper has a copper content of 98%. The remaining 2% contains precious metals such as silver and gold as well as base metals such as iron and zinc. The electrolytic refining of copper is carried out in a sulphate-containing copper (II) sulphate solution with a crude copper anode and a pure copper cathode. During electrolysis, all metals which are less noble than copper are oxidized and dissolve as cations, while the nobler metals sink as anode sludge.

Reaction equation of electrolytic refining:

Anode

cathode

While the anode slowly dissolves to form the cations, only copper, the electrolytic copper, precipitates at the cathode by reduction of copper ions, with a mass fraction of w (Cu) = 99,99%.

The anode sludge produced as a by-product is later recycled and used as starting material for the extraction of precious metals.

The extraction of copper takes place in Affinerien. In Europe Aurubis AG (formerly Norddeutsche Affinerie) is headquartered in Hamburg, formerly it was also the Duisburg copper smelter (now DK Recycling).

Copper can also be obtained as so-called cement copper by precipitation from copper sulphate solution with iron. The process of precipitation is called cementation. The resulting copper is often contaminated. The precipitation of copper onto iron from naturally occurring metal salt solutions has been practiced in China since 1086 AD.

Copper can also be represented by an aluminothermic reaction. Thermit serves as a mixture of copper (II) oxide and aluminum semolina. The use of a flow agent (eg calcium fluoride) can increase the yield because the elemental metals can not dissolve the resulting slag in the flow agent. The aluminothermic extraction is not economical because of the necessary aluminum.

 

Features
Physical Properties

With a density of 8920 kg / m³, copper is one of the heavy metals that crystallizes face centered cubic and thus has a cubic closest packing with the space group Fm3m (space group number 225). The lattice parameter for pure copper is 0,3615 nm (corresponds to 3,615 Å) for 4 formula units per unit cell.

Copper is a very good conductor of heat. Its melting point is 1083,4 ° C. Similarly, copper is a very good electrical conductor with electrical conductivity of 58 · 106 S / m. Its conductivity is only slightly worse than silver and much better than gold. Since all admixtures dissolved in copper, especially impurities such as phosphorus and iron, greatly reduce the conductivity, the highest purity levels are often sought for conductor materials.

The Mohs hardness of copper is 2,5 to 3, which corresponds to a Vickers hardness (VHN) of 77-99 at a test force of 100 g. Cold forming increases the strength of 150 ... 200 MPa (cast state) to values ​​around 450 MPa. The elongation at break is 4,5% with hardness values ​​around 100 HB. Deformed and subsequently annealed copper with a strength of 200 ... 240 MPa has an elongation at break greater than 38% and hardness values ​​around the 50 HB.

Forging is very possible at temperatures from 700 to 800 ° C. Cold deformations can be carried out well without intermediate annealing.

As a bare metal copper has a bright red color, the line color is pink. The red color is due to the fact that it absorbs the complementary green and blue light slightly more at normal temperature. It starts in the air and turns reddish brown. With further weathering and corrosion, the smooth surface is lost very slowly (often over centuries) and the color changes from reddish brown to blue-green due to the formation of a patina.

Chemical properties

Copper occurs in the oxidation states 0, + 1, + 2, + 3 and + 4, most commonly + 1 and + 2, where + 2 is the most stable oxidation state in aqueous solutions; Level + 4 is extremely rare (for example, in Cs2CuF6). Copper (II) salts (eg copper sulphate) are mostly of blue or green color. Copper has some similar chemical properties to silver and gold in the same group. A layer of metallic copper is deposited on an iron nail immersed in a solution of copper sulphate, for which iron dissolves as iron sulphate, because iron is less noble than copper (see also voltage series). Copper is not normally attacked by hydrochloric acid, but it is strongly attacked by oxygen, and is dissolved by hot sulfuric acid. It also dissolves in nitric acid and aqua regia. A mixture of hydrochloric acid or sulfuric acid with hydrogen peroxide dissolves copper very quickly. The metal is also attacked by organic acids. Against alkalis it behaves stably. At red heat, it reacts with oxygen to form a thick layer of copper oxide. Copper is passivated by fluorine and its compounds. Depending on the grain size, copper powder is flammable or combustible. The metal in a compact form is not flammable and is not further attacked by the formation of a thin oxide layer of air and water, so it is resistant to clean air and water.

In liquid copper, oxygen and hydrogen dissolve, which can turn into steam upon solidification of the melt and thus form the cause of gas porosity in the casting.

In oxygen-containing copper species, cracks and voids may form on contact with hydrogen-containing gases, resulting in the so-called hydrogen embrittlement of copper.

Biological properties

Compared to many other heavy metals, copper is relatively weak for higher organisms. So a person can take 0,04 grams of copper daily without suffering any damage to his health. In free, non-protein bound form, copper has antibacterial properties; one speaks here, as with the silver, of the oligodynamic effect, why z. B. also flower water, which is stored in copper vessels or in which a copper coin is placed, not so fast becomes foul.

Bactericidal properties

Copper is toxic to many microorganisms even at low concentrations. Therefore (but also because easy to install) water pipes are often copper-containing. Due to the bactericidal properties of copper, it is being tested in large-scale tests to determine whether it makes economic sense to equip hospital rooms with copper-plated door handles. For example, a clinical trial of 2008 / 2009 shows that at the Asklepios clinic Wandsbeck, Hamburg, after replacing 50 door handles / plates and light switches, MRSA germs were reduced to 63%. A Chilean study found that 7,2 to 19,7% air humidity reduced copper counts by as much as 92%. A multicentre study of 2010 / 2011 from the USA shows that the infection rate in "copper rooms" drops by nearly 60%, on the copper objects itself by more than 80%. 2013 converted the Department of Paediatrics in Niederberg, North Rhine-Westphalia, to copper alloys.

The toxic effect is that copper ions bind to thiol groups of proteins and peroxidize lipids of the cell membrane, leading to the formation of free radicals that damage the DNA and cell membranes. In humans, for example, in the case of Wilson's disease (copper storage disease), this leads to damage to organs with a high copper surplus.

Copper alloys with a copper content of at least 60% also show a toxic effect against noroviruses.

Action against snails

The snail slime oxidizes the copper in the copper wire or copper foil, which serves as a barrier to endangered plants. This creates an irritating substance that prevents the snail from crawling further.

Organic copper needs

In most multicellular organisms, copper is a component of many enzymes (metalloenzymes) and therefore a vital trace element. Copper is part of the blue hemocyanin, which serves as a blood dye in molluscs and arthropods for oxygen transport.

The daily requirement of an adult human is 1,0-1,5 milligrams. In the human body, copper is mainly stored in the liver.

Copper is mainly found in chocolate, liver, grains, vegetables and nuts. Copper deficiency rarely occurs in humans, mainly in long-lasting diarrhea, precocious children, after prolonged malnutrition or malabsorption by diseases such. Sprue, Crohn's disease or cystic fibrosis. The intake of high doses of zinc, iron or molybdate can also lead to reduced amounts of copper in the body. Menkes syndrome is a rare congenital copper metabolism disorder.

Excess copper is released into the digestive system with the bile for excretion.

Copper sulphate (copper vitriol) is a strong emetic and has therefore been used to treat many intoxications, such as white phosphorus, which in this particular case also has the advantage of simultaneously binding the phosphorus as a sparingly soluble copper phosphide.

In the rare hereditary disease Wilson's Disease copper excretion is impaired and there is an increase in copper accumulation, first in the liver, then, when this excretes the copper in the bloodstream, in other organs. Another equally rare disease of copper metabolism is Menkes syndrome. Although the copper can be taken up by the cells, then they can not be further transported in an orderly manner, so that some organs have an increased copper content and others a lower copper content.

Copper and Alzheimer's disease

Again and again the relationship between copper and the development of Alzheimer's disease was discussed. Already 2003 researchers suggested that copper slows down the production of amyloid A and that a lack of copper promotes Alzheimer's disease. However, a subsequent pilot study with 70 Alzheimer's disease patients did not show any protective effect from increased copper intake, even though Abeta42 waste was stabilized in cerebrospinal fluid, a disease marker of Alzheimer's disease.

Other studies showed that copper could be harmful to the brain. Thus, a study with the ionophore PBT2 as an active ingredient against Alzheimer's showed good results in a phase II study. The active ingredient binds not only zinc but also copper and thus reduces the concentration of copper in the brain.

A new study shows that copper accumulates in the brain capillaries at long-term high intake and can damage the blood-brain barrier there. As a result, the removal of beta-amyloid is hindered, the accumulation of the substance then causes Alzheimer's disease.

Usage

Copper is used purely or as an alloy in electrical installation, for pipelines (heating, water, gases), for precision parts, coins, cutlery, works of art, musical instruments and much more.

When used in contact with other metals, it will cause contact corrosion when exposed to moisture.

After silver, copper has the second highest electrical conductivity of all substances even before gold and is therefore used among other things for:

electrical cables, jumper wires and small cross-section power cables, overhead lines
Printed circuit traces on printed circuit boards and partly in integrated circuits
Electrical machines: Wire windings in transformers, inductors / coils and electric motors
Components: anode bodies of magnetrons, clamps, component connection legs, contact carriers, press sleeves

Although aluminum is cheaper and based on the mass per length a better electrical conductor than copper. It is however voluminous. U. a. Therefore, and because copper can be better contacted and it has a higher resistance to bending, it is usually preferred as a conductor to aluminum, except when it comes to weight or price.

Wires and strands made of so-called Oxygen Free Copper (OFC, English for oxygen-free copper with a purity of> 99,99%) have a very fine-grained crystal structure and a particularly high fatigue strength. They are used for cables and wires that are subject to high mechanical stress.

For overhead lines, alloys of copper and magnesium are used. A compromise between increasing tensile strength and decreasing conductivity must be found.

Copper has a high reflectivity in the infrared range and is therefore used as a mirror for carbon dioxide laser radiation and for glass coating (insulating glass).

Because of its high thermal conductivity and corrosion resistance, it is well suited as a material for heat exchangers, heat sinks and mounting plates of power semiconductors.

In arts and crafts copper sheet is driven, that is deformed by hammering, which is easily possible due to its softness. In the fine arts, copper is still used today for the production of printing plates for engravings and etchings.

Even roofs are covered with copper sheet, which then forms a persistent greenish patina, which consists of various basic copper or copper carbonates. Often mistakenly called "verdigris" (see Copper Acetate), this patina protects the underlying metal well from further corrosion, so that copper roofs can last for several centuries. Copper nails are used in the traditional slate roof.
alloys

Copper is also part of many alloys such. As brass (with zinc), bronze (with tin) and nickel silver (with zinc and nickel). These copper alloys are widely used because of their good properties, such as color, corrosion resistance and processability. Wrought alloys (brass and nickel silver) and cast materials (gunmetal, bronzes): Wrought alloys are brought into the desired shape by plastic forming (hot forming: rolling, forging, etc. or cold forming: wire drawing, hammering, cold rolling, deep drawing, etc.), while cast materials usually difficult or impossible plastically moldable.

Depending on the addition of nickel, the copper color disappears and yellowish to white corrosion-resistant alloys (cupronickel) are formed.

Many coin materials are made of copper, so the "Nordic Gold" called metal of the gold-colored parts of the euro coins is a copper-zinc-aluminum-tin alloy. The coin metals of the 2001-DM coins valid until 1 and the bright portions of the euro coins are made of cupronickel alloys.

Copper compounds are used in color pigments, as toners, in medical preparations and galvanic surface coatings.

Price history

Copper is a relatively expensive metal. Its price is largely due to the major commodity exchanges and commodity futures exchanges in the world. The leader in copper trading is the London Metal Exchange (LME).

The world market price for copper is subject to strong fluctuations: The largest fluctuation he experienced in the last 10 years in the year 2008, as the price of copper at 2. Was traded on the LME at the interim high of 8.940 USD / t on July and up to the 23. December 2008 fell to its 10 annual low of 2.825 USD [55]. Thereafter, the copper price recovered in less than 4 months (15 April 2009) back up to 4.860 USD / t. Its 10 high for the year was the price of copper on the 14. February 2011 with 10.180 USD / t.

From March 2012 to March 2013, the copper price rose in the top (2 April 2012) except for 8.619,75 USD and 2. August 2012 down to 7.288,25 USD. A similar spread was also seen from October 2012 to March 2013 between 8.350 USD / t and 7.577 USD / t.

In August 2014, the world market price for copper was around 7.000 USD / t. At the exchange rate at the time, these were 6.199 EUR / t.

The high copper price also causes an increase in thefts of copper-containing objects. Particularly affected here are earthing cables of railways. For example, in the year 2015, Deutsche Bahn AG incurred around 14 million Euro in losses.

One of the biggest financial scandals in recent history is the Sumitomo Affair. It was based on the trade in copper. As a result of the disclosure, 1996's copper price dropped 27% within one day.

 

Price for copper cathodes

Price for copper concentrate

Price for copper ingot

Price for copper powder

Price for copper powder isotope

Production of copper powder isotope