Copper mining is closely related to the technology of extracting metal from ore and is carried out in cost-effective ways, taking into account the specifics of the deposit.
Technology of production of copper products.
Mineral base for metal extraction
The raw materials for copper ore mining are natural mineral formations in which the metal component is contained in quantities necessary for economically viable industrial development.
Raw materials for copper ore mining.
Ore deposits are represented by silicate, carbonate, sulfate compounds, and oxides formed in the oxidation zone.
Among the explored minerals for industrial development are:
- chalcopyrite;
- chalcocite;
- bornite;
- cuprite;
- native copper;
- brochantite;
- azurite;
- cubanite;
- malachite;
- chrysotile.
In ore, the metal concentration is 0.3–5%, and in minerals the concentration is 22–100% (native metal). Copper deposits are in a genetic relationship with other valuable components that are mined as additional chemical elements to the main process.
Among the associated components are:
- platanoids;
- silver;
- gold;
- tellurium;
- gallium;
- molybdenum;
- bismuth;
- nickel;
- titanium;
- zinc.
The ore for copper extraction contains arsenic, antimony, and less commonly mercury. Depending on the type of associated chemical elements There are different types of deposits, among which the main ones are:
- copper-nickel;
- copper-pyrite;
- cuprous sandstones and shales;
- copper-porphyry.
Skarn metal deposits and quartz-sulfide formations are of subordinate importance. In the future, ferromanganese nodules located in the bottom sediments of the World Ocean are considered as raw materials for industrial metal production.
Extraction methods
How is copper mined from ore deposits? Low concentration of metal in the rock requires processing large quantity material. To obtain a unit of metal mass, you need to process 200 units of ore.
Copper, which is mainly mined using the open-pit method, is located at a depth of up to 1000 m. The depth of open-pit mining reaches 150–300 m, and in some cases up to 600 m. Deposits located at a depth of up to 1000 m are developed using the underground method.
Processing ore in search of copper.
Certain standards regulate the feasibility of deepening developments in order to extract ore raw materials. This is due to production technology, additional costs and reduced equipment productivity, which increase the cost of raw materials.
Therefore, the metallurgical industry widely uses the open method, which is characterized by insignificant losses during development. Although there are also disadvantages associated with storing waste rock.
For example, in 2013, a landslide occurred at the Kennecott Utah Copper Bingham Canyon Mine in the United States. The depth of the Bingham Canyon quarry is about 1 km, and the diameter is about 4 km. Ore was mined here for 150 years.
Delivery of raw materials to the processing site was carried out by vehicles with a carrying capacity of 231 tons. The miners were warned about the dangerous phenomenon and were prepared for developments. The quarry wall was moving at a rate of several inches per day, and attempts to strengthen it did not produce the desired result.
The conditions for the extraction of raw materials require the use of sequential development technology using:
- self-propelled equipment;
- conducting work during the extraction of raw materials;
- filling the mined-out space with special materials for the purpose of safety of further development.
Every technological process provides for a reduction in losses during deposit development and an improvement in ore output.
By extracting ore in layers, full use of reserves is ensured. In deep quarries, cyclic-flow technology is used, taking into account the peculiarities of ore occurrence.
Metal extraction technology
To separate rocks that do not contain a valuable component, the flotation method is used. Only a small amount of raw materials containing copper in high concentrations is subjected to direct smelting. Metal smelting involves difficult process, including the following operations:
- burning;
- fuse;
- conversion;
- fire and electrolytic refining.
Melting of raw materials.
During the roasting process of raw materials, the sulfides and impurities contained in it are converted into oxides (pyrite is converted into iron oxide). The gases released during roasting contain sulfur oxide and are used to produce acid.
Metal oxides formed as a result of the influence of a temperature gradient on the rock are separated in the form of slag during firing. The liquid product obtained from remelting is subjected to conversion.
Valuable components are extracted from blister copper and harmful impurities are removed by fire refining and other metals are removed by saturating the liquid mixture with oxygen and then pouring it into molds. Castings are used as an anode for the electrolytic method of purifying copper.
The raw material, which contains copper and nickel, is subjected to enrichment using a selective flotation scheme in order to obtain a metal concentrate. Iron-copper ores undergo magnetic separation.
Cuprous sandstones and shales, gangue and native metal ores are processed to extract copper concentrate. Enrichment is carried out using the gravitational method.
The flotation method is used for mixed and oxidized ores, but chemical methods and bacterial leaching are more often used.
Concentration of ore with low copper content can be carried out using a hydrometallurgical method, which consists of leaching copper with sulfuric acid. Copper and related metals, including precious ones, are separated from the resulting solution.
Metals in the copper subgroup are characterized by low chemical activity, for this reason they are found in the form of chemical compounds, as well as nuggets. Many centuries ago, copper could only be found in the form of sulfur compounds - chalcopyrite and chalcocite. This is because copper has a high chemical affinity for sulfur. Most primary ores contain copper in sulfide form - CuS.
Over time, especially under conditions of volcanic activity, under the influence of large amounts of oxygen, copper sulfides became oxides. Copper nuggets were formed in nature during the strong heating of oxidized sulfur ore. For example, if oxidized copper minerals and sulfur ores lay under a thick layer of rock, they were heated by natural disasters and earthly heat. In such natural “metallurgical shops” colossal volumes of copper were smelted. A nugget weighing 420 tons was found in North America. However, this is rare; native copper on the planet is approximately 1%.
World copper deposits
A lot of copper, like other minerals, is located at the bottom of the oceans. At the bottom there are clusters of round stones containing approximately 0.5% copper. According to the analysis of geologists, the reserves of copper ore in the ocean reach 5 billion tons.
There are almost 250 copper minerals, but only 20 are used industrially. The main copper ores include:
- chalcocite - Cu 2 S, which contains 79.8% copper
- chalcopyrite - CuFeS 2, which contains 30% copper. This ore accounts for almost 50% of all copper deposits
- bornite - Cu 5 FeS 4, contains from 52 to 65% copper
- covellite - CuS, contains 64% copper.
According to genetic and industrial-geological parameters, copper deposits are:
- stratiform, which include copper shales and sandstones
- pyrites. This group includes native and vein copper
- hydrothermal
- igneous, including the most common ores of the copper-nickel type
- carbonate. This group includes iron-copper and carbonatite ores.
Copper reserves in the world
The largest amount of copper, approximately 65%, occurs in the Northern and South America. European states have 15% of resources, Asian states - 11%, African states - 4.5%.
The largest confirmed copper reserves are recorded in Chile. Almost 20% of the world's reserves are located there. And in the USA - 12.7%. In addition to these countries, there is a lot of copper in Poland, Indonesia, Iran, Kazakhstan, China, Uzbekistan, the Philippines, as well as in Zaire, Zambia, Brazil, Canada, Mexico, Panama, Peru and Australia. In each of these states, according to experts, there are about 10 million tons.
Copper ore mining
Due to the low copper content in the ore, its extraction involves processing large volumes of rock. In order to smelt 1 ton of copper, over 200 tons of ore must be processed.
Copper mining methods:
- open method. If ore deposits are located close to the earth's surface, then they are developed in this way; the depth of open-pit mining is 150-300 m. The method is characterized by lower losses
- underground method. Using this method, ore is mined from a depth of 500 m, and sometimes from 800-1000 m.
There are five technological systems for field development:
- using self-propelled equipment. This technology is widely used
- using continuous vibration mechanisms
- using hardening goaf backfill. In this case, there is a continuous excavation of reserves of powerful deposits with minimal losses. With the use of such systems, losses are reduced by 3-4 times
- method of extracting ore in horizontal layers. When filling goafs (in underground mines) with hardening compounds, pipes lined with rubber or basalt are used, the service life of which is 50-100 times higher than that of steel
- cyclic-flow technology for the implementation of mining operations.
Copper production centers
Copper production centers are present in different regions of Russia. Kazakhstan boasts the richest ore deposits. There are also deposits in the Urals. According to the latest data, Russia ranks first in the world in copper ore mining.
Copper plants are being built in close proximity to the mines. The raw material factor is the determining component, due to the low content of concentrates in the feedstock. There are 11 copper complexes located in the Urals, producing 43% of the country’s copper. In addition to our own raw materials, production also uses materials imported from Kazakhstan. There are also waste recycling plants. For example, sulfur dioxide gases, as a byproduct of copper mining, are used to create sulfuric acid, which is then used to make fertilizers.
The most common copper ore on our planet is bornite. But besides it, copper is also mined from other ores, which we will talk about in this article.
1
This ore refers to accumulations of minerals in which copper is present in such quantities that are considered suitable for processing for industrial purposes. A generally accepted indicator of the reasonableness of developing a deposit is considered to be a situation when copper accumulations in it are at least 0.5–1%.
Moreover, about 90% of the reserves of this metal on earth are found in ores containing not only copper, but also other metals (for example, nickel).
Large-scale copper mining in Russia is carried out in Eastern Siberia, in the Urals and the Kola Peninsula. The largest deposits of this metal are present in Chile (according to experts, about 190 million tons). Other countries engaged in the development of such ores include the USA, Zambia, Kazakhstan, Poland, Canada, Zaire, Armenia, Congo, Peru, and Uzbekistan. In total, the planet's total reserves of copper in explored deposits are approximately 680 million tons.
All copper deposits are usually divided into six genetic groups and nine industrial geological types:
- stratiform group (copper shales and sandstones);
- pyrite (native copper, vein and copper-pyrite type);
- hydrothermal (porphyry copper ores);
- igneous (copper-nickel ore);
- skarn;
- carbonate (iron-copper and carbonatite type).
In our country, the main extraction of copper is carried out on cuprous shales and sandstones, from copper pyrites, copper-nickel and porphyry copper ores.
2
In nature, copper is quite rare in its native form. Most often, it “hides” in various connections. The most famous of them are the following:
3
Other copper minerals are much less common, among which are the following:
4
This metal, whose characteristics (for example, high ) have led to its wide demand) is obtained from the minerals and ores described by us in three ways - hydrometallurgical, pyrometallurgical and electrolysis. The most common is pyrometallurgical technology, which uses the mineral chalcopyrite as a feedstock. General scheme The pyrometallurgical process includes several operations. The first of them is the enrichment of copper ore by oxidative roasting or flotation.
The flotation method is based on the difference in wettable gangue and copper-containing particles. Due to this, some mineral elements adhere (selectively) to the air bubbles and are transported to the surface by them. Such simple technology makes it possible to obtain a powdered concentrate in which the copper content varies from 10 to 35 percent.
Oxidative roasting (not to be confused with) is more often used when the initial raw material contains sulfur in large quantities. In this case, the ore is heated to a temperature of 700–800 degrees, which leads to the oxidation of sulfides and a halving of the sulfur content. After this, smelting is performed for matte (an alloy with iron and copper sulfides, produced in reverberatory or shaft furnaces) at a temperature of 1450 degrees.
The copper matte, which is obtained after all these operations, is blown in horizontal converters without supplying additional fuel ( chemical reactions provide the heat necessary for the process) with side blast for the oxidation of iron and sulfides. The resulting sulfur is converted into SO2, and the oxides into slag.
As a result, what comes out of the converter is so-called black copper, in which the metal content is approximately 91%. Subsequently, it is purified using fire refining (removing unnecessary impurities) and an acidified solution of copper sulfate (copper). This type of purification is called electrolytic, after which the copper content reaches 99.9%.
In the hydrometallurgical method of copper production, it is obtained by leaching the metal with sulfuric acid (a very weak solution) and separating copper, as well as other precious metals, from the resulting solution. This technique is recommended for working with low-grade ores.
Before you throw away the old ones household electrical appliances you can benefit from them in the truest sense of the word. Most electrical appliances contain , which can be very profitably handed over to specialized collection points. Of course, dismantling only your own broken equipment big money You won’t be able to make money, but if you take the matter seriously and collect scrap metal from relatives, friends and landfills, you can significantly replenish the family budget.
Main sources of copper.
One of the most expensive and common metals in household use is copper. It is this metal that attracts the attention of scrap collectors more than others, due to its high cost and widespread use due to its properties.For example, an old tube TV may contain copper parts weighing up to 1.5 kg. Things are worse with new models of semiconductor TVs, however, they can also collect up to 0.5 kg of copper. Compression refrigerators and electric motors, the copper content of which reaches 1 kg, are also distinguished by a good content of copper windings and spare parts. But often the copper parts in them are located inside an aluminum or, even worse, cast iron body, which requires the use of a “grinder” and significantly complicates the extraction of copper scrap.
You can get copper for scrap metal and in such devices as: starters, relays, magnetic starters, fittings fluorescent lamps. The yield of pure metal in these parts is not very high, but due to their wide distribution and widespread use, they are quite attractive sources of non-ferrous scrap.
How to collect copper correctly?
To optimize the collection of scrap metal, it is necessary to develop an algorithm for the collection of copper-containing devices, their delivery to the dismantling site, the disassembly itself and, of course, delivery to the collection point. The main sources of copper scrap include landfills, construction sites and abandoned transformer boxes. A garage can serve as a place for disassembly and storage. You can, of course, carry out the analysis directly on the spot, but for this you will have to constantly have with you all necessary tool, so this option is only suitable if you have a car.Getting copper to sell for scrap is only half the battle. The most important thing is to sell the mined metal profitably. During the year, prices for scrap non-ferrous metals can fluctuate greatly, and since summer is the main season for copper mining, it is highly undesirable to hand over it during this period. It is better to store the mined copper until winter and wait for an increase in the price of reception, this way you can sell the copper for scrap metal more profitably.
There are not many metals on our planet whose production volumes exceed those of copper. The twenty-ninth number in Mendeleev’s periodic table is in honorable third place in terms of production levels, right after iron and aluminum. Too many industries would be in trouble if their storerooms suddenly ran out of much-needed metal. The importance of copper and copper ore can hardly be overestimated for electrical engineering, heating engineering, metallurgy, medicine and even transport.
What is copper ore
Copper ore, like any other, is a conglomerate of substances, rocks, minerals, the content of the desired substance in which is so high that it is considered appropriate for mining. It is worth saying that together with the so-called Cuprum ( Latin name copper), its ore is also mined in even smaller proportions by other useful elements. Copper itself begins to be mined in ores in which its amount exceeds 0.5%.
Yes, in its pure form, copper is found in nature even more often than aluminum, but still this figure is approximately one percent of the global reserves, because mining is still carried out from ores. The following groups of ores are distinguished by places of formation and composition: carbonate, sulfide, copper-nickel, porphyry copper (hydrothermal), skarn, stratiform.
Differences in saturation
There are a lot of variations of copper compounds with other substances in ores, about two and a half hundred. We will look at the most popular and most intense:
- Bornite. Most often it belongs to the hydrothermal group of ores and may contain about 65% Cuprum. Chem. formula – Cu 5 FeS 4;
- Kovelin. Also a member of the hydrothermal group, up to 64% copper. Formula – CuS;
- Chalcopyrite. Hydrothermal group. Copper saturation is 30%. The most popular ore is 50% of all deposits. Formula – CuFeS 2;
- Chalcocine. Leader in terms of saturation. 79.8% “red metal”. Still the same hydrothermal group. Formula – Cu 2 S.
Copper ore mining methods
There are two methods of mining - mine and open pit. That's all that modern technologies can boast of during ore mining. The open method is used in cases where the copper deposit is not located very deep underground (about 400-500 meters). First, a layer of waste rock is removed, and then the mining process itself begins, to facilitate which directed explosions are used.
In the case of the shaft method, as the name implies, a shaft is punched. The depth sometimes reaches a kilometer. The mines are equipped with elevators for transporting equipment and workers, as well as for transporting the resulting ore to the top. Studded drilling machines, biting into the rock, extract from the mines necessary for production ore.
Processing the resulting ore
As of today, there are 3 ways to process the resulting copper ore. Pyrometallurgical, hydrometallurgical and electrolysis.
The pyrometallurgical method is the most popular. The most common chalcopyrite is taken as the “working material”.
At the very beginning, enrichment is performed. For this purpose, the oxidative firing method is used. This method is very suitable for chalcopyrite, since it is primarily designed for ores with high sulfur concentrations. With this technology, the ore is heated to high temperatures(sometimes up to 8 thousand degrees Celsius), during which sulfur and oxygen interact, after which almost half of the sulfur evaporates. Next, the ore is heated even more in shaft or reverberatory furnaces. We are already talking about 1.4-1.5 thousand degrees.
Sometimes fake jewelry is made from copper, as a similar-colored material. To avoid counterfeits, be aware that copper darkens over time, and a metallic smell remains in the water.
The output, after exposure to such temperatures, is an alloy of copper and iron sulfides - matte. The alloy is blown through convectors, due to which both iron and sulfur are oxidized once again, evaporating in some places and settling as slag in others. The product becomes 91% blister copper.
In order to achieve almost standard copper content in the alloy, fire refining technology is used. An acidified solution of CuSO 4 is also used with it. After these manipulations, which, by the way, are called electrolytic refining of copper, we get “pure” copper, with a concentration of 99.9%.
Copper mining in the world
Chile holds first place both in copper reserves and in its production on planet Earth. A third of the world's reserves are concentrated here. Copper has been mined in the Chuquicamata deposit for over 100 years. During this time, more than 26 million tons were mined. America and China take second and third places. In terms of the amount of copper ore in Russia, the country ranks fifth in the world along with Poland and Indonesia. Each country contains 4% of the world's reserves of this mineral.
Copper and copper ore in Russia
In Russia, copper ore reserves include the Norilsk, Oktyabrskoye, and Tapakhninskoye deposits. They contain about 60% of the country's copper reserves. The recently discovered Udokan mine (Chita region) can supply the country with ore for about 30 years. But so far no work has been carried out in this place, since it is located in a place with rudimentary transport links.
Copper Applications
It is easier to indicate areas where copper is not used than to cover all areas of its use. After all, even in the human body there is a need for a daily dose of copper (about 0.9 mg per day).
Due to its low resistivity, Cuprum is used for the production of wires, cables, electrical coils, transformers and other electrical equipment.
Due to its high thermal conductivity, copper, in turn, is involved in the design of elements of cooling, heating, and air conditioning systems.
In one area of transport, namely pipelines, seamless copper pipes have become an ideal container for transporting both water and gas.
Jewelers use an alloy of gold and copper to strengthen the former. Since gold, in itself, is a very soft metal, and products without copper admixture would be extremely susceptible to deformation.
Due to the discovery of the bactericidal properties of copper, in the future it has a chance to be widely used in medicine, both for the manufacture of tools and work surfaces, and as a material for ordinary door handles.