Bauxite. Bauxite - formula, chemical properties and applications For bauxite, a harmful impurity is

BOXITES [by name. area of Les Baux (Les Baux) in the south of France, where deposits of bauxite were first discovered], bauxite, consisting mainly of aluminum hydroxides (alumogel, gibbsite, boehmite, diaspore, etc.), oxides and hydroxides of iron and clay minerals. The color is red in various shades, brownish-brown, less often white, yellow, gray (to black). They occur in the form of dense (stony) or porous formations, as well as in the form of loose earthy and clay-like masses. According to the structure, detrital (pelitic, sandstone, gravelite, conglomerate) and nodules (oolitic, pisolithic, legumes) are distinguished; texture - homogeneous, layered and other bauxites. Density varies from 1800 kg/m 3 (loose) to 3200 kg/m 3 (stony). According to the predominant mineral composition, bauxites are distinguished: monohydroxide (diaspore, boehmite), trihydroxide (gibbsite) and mixed composition (diaspore-boehmite, boehmite-gibbsite, chamosite-boehmite, chamosite-gibbsite, gibbsite-kaolinite, goethite-chamosite-boehmite, etc.). ).

Bauxites are formed during deep chemical transformations (laterization) of aluminosilicate rocks in a humid tropical climate ( lateritic or residual bauxites) or during the transfer of laterite weathering products and their redeposition (sedimentary bauxites). As a result of the superimposition of these processes, bauxites of a mixed (polygenic) type are formed. The deposits are layer-like, lenticular or irregular (karst pockets) in shape. The quality of lateritic bauxites is usually high (50% $\ce(Al_2O_3)$ and higher), sedimentary bauxites can be from high grade (55–75% $\ce(Al_2O_3)$) to substandard (less than 37% $\ce (Al_2O_3)$ ). In Russia, the requirements for the quality of mined (commercial) bauxite are determined by GOST, as well as contractual terms between suppliers and consumers. Depending on the ratio (by weight) of the content of alumina and silica (the so-called silicon module), bauxites are divided into 8 grades. For the lowest grade (B-6, 2nd grade), the flint modulus should be over 2 with an alumina content of at least 37%, for high-grade bauxites (B-0, B-00) the flint modulus should be over 10 with an alumina content of 50% and more. In foreign classifications, bauxites with a flint modulus over 7 are considered high-quality.

Bauxite deposits are divided by reserves into large (over 50 million tons), medium (5–50 million tons) and small (up to 5 million tons). The reserves of the world's largest Boke deposit (Guinea) are estimated at 2.5 billion tons. 83.7% of the reserves are concentrated in deposits of the lateritic type, 9.5% of the polygenic type and 6.8% of the sedimentary type.

Bauxite deposits have been explored in more than 50 countries around the world. The total reserves of bauxite are estimated at 29.3 billion tons, confirmed - at 18.5 billion tons (second half of the 2000s). The largest proven reserves are: Guinea (7.4 billion tons; St. 40% of world reserves), Jamaica (2 billion tons; 10.8%), Brazil (1.9 billion tons; 10.3%) , Australia (1.8 billion tons; 9.7%), India (0.77 billion tons; 4.2%), Guyana (0.7 billion tons; 3.8%), Greece (0. 6 billion tons; 3.2%), Suriname (0.58 billion tons; 3.1%), China (0.53 billion tons; 2.8%). The largest in the world is the West African bauxite-bearing province (or Guinea).

In Russia, the total reserves of bauxite are over 1.4 billion tons, confirmed reserves are over 1.1 billion tons (beginning of 2013). There are 57 deposits (including 4 large and 7 medium). The main bauxite reserves are concentrated in Sverdlovsk region(about 1/3 of the reserves of the Russian Federation; sedimentary deposits of the North Ural bauxite-bearing region - large Cheremukhovskoye, medium - Krasnaya Shapochka, Kalinskoye, Novokalyinskoye), Komi Republic (26% of the reserves of the Russian Federation; polygenic deposits of the Vorykvinskaya group of the Timan bauxite-bearing zone - large Vezhayu-Vorykvinskoye, medium - Verkhneshchugorskoye, Vostochnoye), Arkhangelsk region (18% of the reserves of the Russian Federation; large Iksinskoye sedimentary deposit), Belgorod region (about 16% of the reserves of the Russian Federation; large Vislovskoye laterite deposit, medium - Melikhovo-Shebekinskoye). Bauxite reserves have also been identified in the Krasnoyarsk and Altai Territories, the Kemerovo Region, the Republic of Bashkortostan, and the Leningrad Region. Ores from Russian deposits compared to foreign analogues are of lower quality and more difficult development conditions. The richest ores ($\ce(Al_2O_3)$ 56%) in the deposits of the Northern Urals; the largest (about 18% of the reserves of the Russian Federation) Iksinskoye deposit is composed of low-quality bauxites.

The world production of bauxite exceeded 196 million tons/year (2nd half of the 2000s). Main producing countries: Australia (62.6 million tons/year), China (27 million tons/year), Brazil (22.8 million tons/year), Guinea (18.2 million tons/year), Jamaica (14.9 million tons/year), India (13.9 million tons/year). In Russia, the extraction of bauxite from the bowels in 2012 amounted to 5.14 million tons; 9 deposits were developed, 6 of them in the Sverdlovsk region.

Alumina and aluminum are extracted from bauxite. Bauxites are also used in the production of paints, artificial abrasives (electrocorundum), as fluxes in ferrous metallurgy, sorbents for the purification of petroleum products from various impurities; low-iron bauxites - for obtaining high-alumina refractories, fast-hardening cements, etc. Bauxites - complex raw materials; in addition to aluminum and iron, they contain gallium, as well as titanium, chromium, zirconium, niobium, and rare earth elements.

Sometimes in the news you can hear such a term as "bauxite". What are bauxites, why are they needed? The purpose for which they are used, where they are mined and what features they have, will be discussed in the article.

General concept

Bauxite got its name from the area in the south of France, which is called Les Baux. What bauxites are, it becomes clear when you get acquainted with their description. This is an ore of aluminum, which consists of a hydrate of oxides of iron, silicon, aluminum. Bauxite is also used as a raw material for the production of alumina-containing refractories. In industrial substance, the content of alumina ranges from 39 to 70%. In addition, the mineral is used as a flux in the manufacture of ferrous metals.

Today, bauxite mining is the most important source of aluminum ore. It is on this that almost the entire world metallurgical industry is based, with minor exceptions.

Compound

Considering in more detail what bauxite is, it can be noted that it is rock, which is quite complex. It includes substances such as aluminum hydroxide, silicates and iron oxides, as well as silicon in the form of opal, quartz and kaolinite.

In addition, titanium is found in the composition in the form of an oxide mineral (rutile and other compounds), magnesium carbonate, calcium, sodium, zirconium, chromium, phosphorus, potassium, gallium, vanadium compounds and other elements. Sometimes pyrite impurities are found in bauxite alumina.

Value

The chemical component of the mineral varies quite widely. First of all, the difference in indicators is influenced by the mineralogical form of aluminum hydroxide, as well as the amount of various impurities. A bauxite deposit is considered valuable if the ore mined contains sufficient amounts of silica and alumina. Also important role plays the so-called opening of bauxites. In other words, it is the ease and simplicity of its extraction.

Bauxites have a variety of physical properties. They have a rather unstable appearance, and therefore it is difficult to determine their quality by visual signs. This is what causes great difficulties in the search for the mineral. Therefore, rock samples are examined under a microscope before a decision is made to start mining.

Appearance

Continuing to consider what bauxite is, you should pay attention to their appearance. They are clay-like, and often stony. There are bauxites quite dense, porous, with earthy or cellular fracture. Quite often, in the groundmass one can meet the inclusion of rounded bodies, which create an oolitic (sedimentary) structure of the ore.

Bauxites come in a variety of colors ranging from dark red to white. Basically they are painted in red brick or brown color. There is also a mineralogical difference between bauxites. It lies in the fact that in their composition there is a high content of aluminum in the form of hydroxide or kaolinite (aluminum silicate). In this regard, several types of bauxite are distinguished: diaspore, boehmite, mixed, and hydrargillite.

Mining

More than 90% of bauxite reserves in the world are concentrated in 18 countries. Impressive deposits are found in regions with a hot climate. The Russian Federation has small deposits of bauxite and mainly imports raw materials. The largest deposits are in the following countries:

Guinea - about 20 billion tons;
Australia - more than 7 billion tons;
Brazil - about 6 billion tons;
Vietnam - 3 billion tons;
India and Indonesia - about 2.5 billion tons.

In Russia, bauxites of the highest quality are mined in the North Ural region. There are also deposits in the Leningrad region, in the Boksitogorsk region. The most promising source of raw materials are the Sredne-Timan deposits, which are located in the Komi Republic. Explored reserves are presumably estimated at more than 250 million tons.

Application of bauxite

After melting the rock, alumina cement is also obtained. As can be seen, the range of applications of bauxites is quite wide, which makes them a particularly valuable raw material.

Kinds

One of the rare types of bauxite is alunite, which is mined only in Azerbaijan, in the Zaglik deposit. According to the proven proven reserves, it is more than 200 thousand tons.

However, on the territory of Uzbekistan, presumably, there are also reserves of alunite ores. Their deposits were explored in the Gushsai field. Perhaps there is about 130 million tons. However, the development and extraction of these ores is currently not carried out, which allows Azerbaijan to be the only country where alunite is mined.

Features of mining and processing

Bauxite is mined mainly by open pit mining, but in some cases underground. The method of developing a deposit depends on how the mineral rocks are deposited. The technological scheme of processing is used differently, it is affected by the composition of the rock. Aluminum production is carried out in two stages. The first is the production of alumina using various chemical methods, and the second is the isolation of pure metal through the electrolysis of aluminum fluoride salts.

To obtain alumina, the Bayer hydrochemical method (sintering) is used, as well as a combination: serial and parallel methods. The main feature of the Bayer method is that during the leaching (treatment) of bauxite, concentrated sodium is obtained, after which the alumina passes into the form of a sodium aluminate solution. The solution is then cleaned of red mud and alumina (aluminum hydroxide) is precipitated. After that, leaching is carried out, and aluminum is obtained.

Low-quality bauxites are processed in the most difficult way. This is a method of sintering a mixture of crushed bauxite with soda and limestone (three-component charge) at a temperature of 1250 degrees Celsius in special furnaces, which during production process revolve. After that, the resulting material (speck) is leached with a weakly concentrated solution. The precipitated hydroxide is then filtered off.

The above methods for producing aluminum are very complex processes, but they allow you to get the maximum amount of metal from the rock.

Bauxite is the most important source of aluminum, and the metal itself is very valuable, as it is used in the automotive, aircraft and ship industries. It is also widely used in military-industrial complex, which makes this metal strategically important.

The main raw materials of the aluminum industry of the Russian Federation are bauxites, as well as nepheline ores (urtites) and nepheline concentrates of apatite-nepheline ores of the Kola Peninsula. In world practice, the last two are not used for aluminum production because of the expensive process technology.

It should be noted that Russian deposits are characterized by low quality of bauxites and difficult mining and geological conditions, which does not allow maintaining the achieved level of aluminum production from domestic raw materials in the coming years.

In terms of explored bauxite reserves, Russia ranks 7th in the world, while within b. USSR, 77% of the total reserves are concentrated on its territory. Currently, 44 deposits have been explored in Russia, the total reserves of which will be able to ensure the operation of mining enterprises (based on production volumes in 1993) for 240 years. Currently, only 10 deposits are in operation, the total explored reserves of which amount to 32% of Russian bauxite, which ensures the operation of enterprises for 79 years.

Russia over the past 15 years has experienced a steady deficit in bauxite and nepheline. Therefore, annually for the needs of the aluminum industry, the country is forced to import 3 million tons of alumina, which requires the sale of a significant amount of primary aluminum on the foreign market.

Provision of existing mining enterprises with explored reserves is very unequal. For example, the largest Russian enterprise JSC "Sevuralboksytruda" has proven reserves for 52 years, but at the same time, its mines, which develop the "Krasnaya Shapochka" deposit, only for 19 years. Ivdel quarries (Gornostayskoye and Gornostaysko-Krasnooktyabrskoye deposits, Boksitogorsk, Sverdlovsk region) are provided with reserves for 18 years. The most unfavorable state of the mineral resource base of the South Ural bauxite mines (SUBR). The enterprise is finalizing them, and the rest is capable of supplying the Blinovo-Kamenskaya and Kurgazakskaya mines for no more than 10 years. In total, the Radynsky quarry of Baksitogorsky alumina JSC is provided with reserves for 7 years.

The table shows brief data on the largest developed bauxite deposits in Russia.

Significant bauxite reserves are concentrated in the two largest deposits in Russia - Vezhayu-Vorykvinsky (Komi Republic) and Vislovsky (Belgorod region). On the basis of the first, as a priority, VAMI and Gipronickel are designing a quarry for the Sredne-Timansky bauxite mine with a capacity of 3 million tons per year.

In terms of bauxite production, Russia ranks 6th in the world, and among the CIS countries it ranks first (62.7% of total production).

The figure shows the dynamics of production of alumina raw materials at mining enterprises in Russia.

The main method of bauxite mining is underground. For example, out of 3763 thousand tons of bauxite mined in 1995, 3149 thousand tons (83.7%) were mined underground. At the same time, bauxites are mined abroad mainly by open pit mining using powerful open pit equipment (99.8%), which makes extraction cheaper.

Due to a slight increase in the cost of ore mining, limited demand and with the complication of mining conditions (JSC "Sevuralboxytruda") and the depletion of explored reserves (SUBR) for the period 1990-1995. bauxite production decreased by 1,960 thousand tons (34.2%), with the main share of the decline in production occurring at the expense of JSC Severoboksitruda (1,590 thousand tons). The decline in production of the latter was also affected by a very high selling price (65 thousand rubles per ton). With a normal market and the prospect of Russia's integration with the world economy, these bauxites become unattractive for consumers - the Ural and Bogoslovsky aluminum smelters. For the same reason, and also because of the depletion of reserves, production was also reduced at the South Ural bauxite mines.

JSC "Severo-Onega bauxite mine" extracts sintered bauxites, which are labor-intensive in quality for the production of alumina. They do not find a consumer among the alumina industries. Currently, their production has fallen sharply: if in 1990-1991. they were mined 700 thousand tons, then in 1995 only 363.8 thousand tons. Therefore, the main part of the production is sold to the enterprises of ferrous metallurgy and the cement industry.

Russia has huge reserves of nepheline, both in the form of tailings from the enrichment of apatite-nepheline ore on the Kola Peninsula, and in proven reserves in Siberia. Currently, 41% of alumina is obtained from nepheline, but given the higher energy costs than bauxite processing, as well as the poor quality of raw materials, the prospects for increasing production are problematic.

The balance reserves of nepheline ores are contained in 12 deposits, with 81.2% in the Kola Peninsula. Of the others, urtite ores are the richest in nepheline (Kiya-Shaltyrskoye deposit of JSC Achinsk Alumina Refinery). With a design capacity of the open pit of 4.5 million tons of ore per year, production decreased from 4.24 million tons of ore in 1990 to 2.33 million tons in 1995. An alumina refinery produces 730-750 thousand tons of alumina at a design capacity of 900 thousand .tons per year.

Apatite-nepheline deposits of the Kola Peninsula are being developed by Apatit JSC by open pit mining. Nepheline concentrates (1050-1100 thousand tons per year) are obtained along the way, in the production of apatite concentrate.

Extracted and processed alumina-containing raw materials for aluminum production meet the needs of enterprises by 50%. Therefore, many factories prefer to buy imported alumina (from Guinea, Australia, and other countries), which is cheaper than domestic alumina, and sell the resulting aluminum on foreign markets.

Long-term practice and studies of domestic aluminum-containing raw materials (bauxites and nephelines) have shown low competitiveness due to its unsatisfactory quality and high production costs (most bauxites are mined at great depths). The silicon modulus of domestic bauxite is on average 5, foreign 8-15. In addition, the processing of Russian bauxites requires more complex technologies and significant costs.

An analysis of the reporting indicators of the last five years has shown that the mining enterprises of the aluminum sub-sector of Russia (as well as the entire aluminum industry as a whole) in terms of their technical and technological levels lag far behind the similar industry in the world.

Before the start of perestroika, practically no one solved the issue of reconstructing enterprises. Today he is extremely aggravated. Given the disrupted interstate, and hence interconsumer investment.

Competitiveness of the ore resource base of the aluminum sub-sector is expected to be increased due to the commissioning of the Sredne-Timansky bauxite mine in the next 5 years for the extraction of 3 million tons per year of relatively high-grade (at the level of imported) and inexpensive (open-pit mining) bauxites of the Vezhayu-Vorykvinsky deposit.

As a result of the policy of the Russian government over the past two years, objective prerequisites have been created for the integration of the aluminum industry of the CIS countries through the consolidation of stakes in privatized enterprises, incl. and the aluminum mining sub-sector.

What is bauxite?

Bauxite- This is a natural stone, whose birthplace is France. It was in the south of this country that this aluminum ore was first discovered. The name "bauxite" also comes from the French word "bauxite".

The name is associated with the area called Lebo, where this stone was discovered. In this article, we will consider both physical and chemical bauxite properties, but first, let's figure out the composition and determine what components are included in it.

Description and properties of bauxite

So what is this breed? Bauxite is commonly referred to as aluminum ore. It contains aluminum hydroxide, as well as oxides of chemicals such as silicon and iron.

In addition to these constituent parts, bauxites contain alumina. Its percentage can be from forty to sixty percent and even higher. Bauxite is considered a truly unique and amazing natural stone.

Let's turn to history. For the first time about amazing properties of bauxite was said in 1855 at an exhibition in Paris, the capital of France. There was an interesting stone there. It looked like a beautiful silver color.

Its weight was very small, but it was strong enough from a chemical point of view. This metal at the exhibition was signed as "clay silver". This description talks about the properties and type of aluminum. But the raw material from which this interesting metal is obtained is called bauxite.

It should be noted that aluminum is obtained only from those bauxites in which the percentage of aluminum alumina is at least forty percent. Bauxites are of great value, from which it is not difficult to get alumina.

By its outward mind bauxite very much like clay, but according to its characteristics, it has nothing to do with it. Bauxite, unlike clay, is completely insoluble in water.

The first location of bauxite deposits on the territory of our country, which were found in the Urals, was called "Little Red Riding Hood". Bauxite is the most important stone from which aluminum is obtained.

Deposits and mining of bauxite

Bauxite- This is a very complex rock in its composition. Alumina hydrates constitute their main part. But besides it, bauxites contain other components. The most harmful component is silicon oxide.

As for other substances, in bauxite it is quite possible to find such components as magnesium oxide, manganese and calcium oxide, titanium dioxide and others. Let's analyze in more detail physical properties of bauxite.

In appearance, bauxite can be red or other shades of it. Bauxite is found in both pink and dark red colors. Also, the stone can have a gray tint from lighter to jet black. If we evaluate bauxite hardness, then this value is 6 on the Mohs scale.

The density of the stone can vary from 2900 to 3500 kilograms per cubic meter. In terms of transparency, bauxite is opaque. Stones can be formed by different minerals. Based on this, the breed can be divided into three main groups.

The first group includes bauxites, for which the rock-forming mineral is diaspore or boehmite. Such bauxites are called monohydrate. In them, alumina is present in only one form.

The next group includes those bauxites, the basis for which are the so-called gibbsites. In such stones, alumina is contained in a three-water form. And the last, third, group includes those bauxites that combine the forms of the first groups.

Bauxite deposit depends on the degree of weathering in a particular zone of acidic, alkaline, and sometimes basic rocks. Also, deposits of bauxite can be formed in the area where alumina is deposited in lake and sea basins.

Thus, two main reasons for the location of bauxites can be distinguished. The first reason is called platform. It is associated with continental deposits that lie horizontally. The second reason is related to the area where the deposits of the coastal-marine type are located.

Almost the entire supply of bauxite on the globe - this is 90% - is concentrated mainly in those countries where the climate is tropical or subtropical.

This is due to the fact that the stone is formed mainly where the active weathering of aluminum rocks occurs and this process continues for a much longer period. The cause of weathering is the climate.

Guinea occupies the first place in the world in bauxite reserves. Its territory contains about twenty billion tons of bauxite. In second place in terms of the number of this stone is Australia. There are approximately seven billion tons of bauxite.

As for Russia, the reserves of this stone in our country are so small that there is not such an amount of ore that would be enough for consumption within the state. The share of world reserves of this type of raw material is only one percent of the world's stone reserves.

The highest quality bauxite deposits in our country are considered to be those located in the North Ural bauxite region. A new area of this raw material is the Sredne-Timanskaya group, which is located in the northwestern region of the Komi Republic. Bauxite is being mined here and this site is considered the most promising than the one that was mentioned at the beginning.

Russia is only in seventh place in the world in the extraction of aluminum ores. Due to the fact that the country itself cannot provide itself with the metal in the required quantity, it has to buy bauxite from foreign countries.

In the territory Russian Federation there are fifty deposits of this ore. This figure includes both areas where bauxite mining is actively conducted, and those where the deposits are not yet fully developed.

Largest part bauxite reserves located in the European part of Russia. This includes the previously mentioned Komi Republic, as well as the Arkhangelsk, Sverdlovsk and Belgorod regions. All these areas contain about seventy percent of all bauxite reserves in our country.

To the old bauxite deposit in Russia, you can call Radynskoye, which is located on the territory of the Leningrad region. Bauxite mining is carried out there to this day.

Locations bauxite deposits can be roughly divided into four groups. The first group is called a unique deposit. In such territories, the amount of ore exceeds five hundred million tons. The second group is large and medium deposits. Here, bauxite deposits range from fifty to five hundred tons.

The last group is small deposits. In such territories the presence of bauxite in figures is less than fifty million tons.

Application of bauxite

The main thing use of bauxite is the ability to extract aluminum from it. But also this stone is used in other areas. In the ferrous metallurgy industry, alumina is still commonly used as a flux.

In addition, bauxite can be used in the production of paints. Thanks to the melting of this stone, alumina cement can also be made. And if melt bauxite in an electric furnace, then electrocorundum can become the final product.

bauxite price

bauxite price depends primarily on the quality of the stone. The total cost will also depend on how much material is ordered. For example, if you buy bauxite wholesale, then the price will drop significantly.

BOXITES (from the name of the locality of Les Baux, Lex Baux, in the south of France, where their deposits were first discovered * a. bauxite; n. Bauxite; f. bauxites; and. bauxitas) - aluminum ore, consisting mainly of aluminum hydroxides, oxides and hydroxides of iron and clay minerals.

The main ore-forming minerals of bauxite are diaspore, boehmite, gibbsite, goethite, hydrogoethite, hydrohematite, kaolinite, chamosite, chlorites, rutile, anatase, ilmenite, aluminogethite, aluminohematite, siderite, calcite, micas. By appearance bauxites are very diverse. Their color is usually red, brownish-brown, less often gray, white, yellow, black. According to the state of aggregation, bauxites are distinguished as dense (stony), porous, earthy, loose and clay-like; according to structural features - detrital (pelitic, sandstone, gravelite, conglomerate) and nodules (oolitic, pisolithic, legume); texture - collomorphic (homogeneous, layered, etc.). Due to different porosity, the density of bauxites varies from 1800 (loose bauxites) to 3200 kg/m3 (stony bauxites).

According to the predominant mineral composition, bauxites are distinguished: monohydroxide, composed of diaspore, boehmite, trihydroxide - gibbsite; mixed composition - diaspore-boehmite, boehmite-gibbsite. There are also more fractional divisions of bauxites depending on the mineral composition: chamosite-boehmite, chamosite-gibbsite, gibbsite-kaolinite, goethite-chamosite-boehmite, kaolinite-boehmite, etc. According to the formation conditions, bauxites are divided mainly into lateritic (residual) and redeposited (sedimentary). Bauxites were formed either as a result of deep chemical processing (laterization) of aluminosilicate rocks in a humid tropical climate (laterite bauxites) or as a result of the transfer of laterite weathering products and their redeposition (sedimentary bauxites). Depending on the tectonic position, bauxites of platform and geosynclinal areas, as well as bauxites of oceanic islands, are distinguished. Bauxites form sheet-like and lenticular bodies of variable thickness, and in terms of the deposit they are linear, isometric and irregular in shape. Often deposits consist of several (in vertical section) lenses. The quality of lateritic bauxites is usually high, while sedimentary bauxites can range from high grade (eg, North Ural deposits) to substandard (Boksonskoye deposit in Buryatia).

Bauxite is the main ore for the extraction of alumina (AL2O3) and aluminum; used in the abrasive industry (electrocorundum), in ferrous metallurgy (flux in the smelting of open-hearth steel), low-iron bauxites - to obtain high-alumina mullitized refractories, fast-hardening alumina cements, etc. Bauxites are complex raw materials; they contain Ga, as well as Fe, Ti, Cr, Zr, Nb, rare earth elements. In the USSR, the requirements for the quality of mined (commercial) bauxite are determined by GOST, as well as contractual terms between suppliers and consumers. According to the classification of the current GOST 972-74, bauxites are divided into 8 grades depending on the weight ratio of the contents of alumina and silica (the so-called flint module). For the lowest grade (B-6, II grade), the flint modulus must be at least 2 with an alumina content of at least 37%, for high-grade bauxites (B-0, B-00) the flint modulus should be more than 10 with an alumina content of 50% or more . Selected grades and grades of bauxite have their own areas of use in industry.

Bauxites are mined by open, less often by underground methods. Choice technological scheme Processing of bauxites depends on their composition. The production of aluminum from bauxites is carried out in 2 stages: at the first stage, alumina is obtained by chemical methods, at the second stage, pure metal is isolated from alumina by electrolysis in a melt of aluminum fluoride salts. When obtaining alumina, the Bayer hydrochemical method, the sintering method, as well as the combined Bayer-sintering method (parallel and sequential versions) are mainly used. The basic scheme of the Bayer process consists in the treatment (leaching) of finely ground bauxite with a concentrated solution of sodium hydroxide, as a result of which alumina goes into solution in the form of sodium aluminate (NaAl3O2). From the aluminate solution, purified from red mud, aluminum hydroxide (alumina) is precipitated. Low-quality bauxites are processed in a more complicated way - the sintering method, in which a three-component charge (a mixture of crushed bauxite with limestone and soda) is sintered at t 1250 ° C in rotary kilns. The resulting cake is leached with a recycled alkaline solution of low concentrations. The precipitated hydroxide is separated and filtered. The parallel combined Bayer-sintering scheme provides for the simultaneous processing of high-quality and low-grade (high-silicon) bauxites in one plant. The sequential combined scheme of this method includes the processing of bauxite into alumina, first by the Bayer method, and then additional extraction of alumina from red helmets by sintering them with limestone and soda. The main bauxite-bearing regions (see map) are located in the European part of the USSR, in the Urals, in Kazakhstan.

In the European part, they are known in the Arkhangelsk region of the RSFSR (Iksinskoe and others), on the Middle (Vezhayu-Vorykvinskoe and others) and Southern Timan (Timsherskoe, Puzlinskoe and others), in Leningrad (Tikhvinskoe) and Belgorod (Vislovskoe and others). ) regions of the RSFSR. In the Urals, bauxite deposits are being developed in the Sverdlovsk (Severouralsk bauxite-bearing region) and Chelyabinsk (South Ural deposits) regions of the RSFSR. Within Northern Kazakhstan, bauxite deposits are concentrated in the Kustanai (Krasnooktyabrskoye deposit, Belinskoye, Ayatskoye, Vostochno-Ayatskoye and other deposits) and Turgayskaya (Vostochno-Turgayskaya group of deposits) regions of the Kazakh SSR. In eastern Siberia, bauxites are found in the region of the Chadobets uplift of the Angara region and in the eastern Sayan (Boksonskoe).

The most ancient bauxites in the USSR are known from the Bokson deposit (Precambrian, Vendian). The bauxites of the North Ural group are associated with deposits of the Middle Devonian, while the Middle Timan bauxites are associated with deposits of the Middle and Upper Devonian. The bauxites of the Iksinsky and Vislovskoye deposits occur in the Lower Carboniferous deposits, the deposits of Northern Kazakhstan were formed in the Cretaceous and Paleogene times and are the youngest.

China has large bauxite reserves (deposits in the provinces of Shandong, Henan, Gansu, Yunnan, Liaoning, Shaanxi, etc.), Hungary (deposits of Khalimba, Nyirad, Iskaszentgyörgy, Gant, etc.), SFRY (deposits of Vlasenitsa, Drnish, Lika Plateau, Bijela-Lipa, Obrovac, Niksic, Bijela-Polyana), bauxite deposits are also known in the SRR, SRV, and the DPRK.

In industrially developed capitalist and developing countries, bauxite reserves at the beginning of 1982 amounted to about 22 billion tons, incl. proven 13.5 billion tons. The main reserves of bauxite fall on the territory of developing countries - about 75% (16.7 billion tons), incl. proved about 75% (10.1 billion tons). AT developed countries deposits of high-quality bauxites are known in the form of lateritic covers in Australia; specific gravity they are in the total reserves of about 20%. The main part of bauxite deposits is located in the little-explored territories of the countries of the tropical belt, therefore, it is assumed that the trend of faster growth of reserves compared to production will continue.

In 1974, the International Association of Bauxite Mining Countries (International Bauxite Association) was established. It first included Australia, Guinea, Jamaica, Guyana, Suriname and the SFRY, then Ghana, Haiti and the Dominican Republic. Brazil, Greece, India, Turkey, the USA and France also have significant bauxite reserves.

Bauxite mining in industrialized capitalist and developing countries in 1981 amounted to 73.0 million tons, incl. in developing countries 40.9, in industrialized countries 32.12. Australia ranks first in bauxite production, followed by Guinea, Jamaica, Suriname, Brazil, and Guyana. In the future, the largest increase in bauxite mining capacity is expected in Australia, Guinea and Brazil. According to forecasts (80-90s), the vast majority of alumina plants will be built in bauxite-producing countries, and the volume foreign trade bauxite, which was about 35 million tons in the early 1980s, will increase at a relatively slow pace.

Bauxite in its original form. Curious about chemical and physical properties

Bauxite in geology:
Complex rock. Consists of aluminum hydroxides, iron oxides and impurities of other elements.
For the production of aluminum, bauxite is used with a high percentage of Al-alumina from 40%. Quality determination is carried out by the ratio of the concentration of alumina and silica.
Bauxite having a slight "opening" is valued. This is a term for the quality and speed of extraction of alumina.
Visually detecting bauxite in a deposit is not easy. The search for this rock is very difficult due to the dispersion of the components. For example, only brightly crystallized impurities can be distinguished under a microscope.

Variety of types of bauxite alumina:
The appearance of the rock is a clay-like or stony mass.
There are dense, flint-like minerals, and there are pumice-like minerals. With the same porous rough cellular fracture. Sometimes in the mass you can find unusual rounded inclusions. Then the structure is called oolitic, and the bodies let you know that the found rock contains raw materials for the production of iron.
The wide range of colors is amazing. Bauxite can be found in gray-whitish, pale cream or dark cherry hues. These are rare cases. More common bauxite is red-brown or brick-red.
The rock is also interesting in that it does not have a clearly defined value of specific gravity, as is the case with sulfur or silicon. Light rocks with a porous structure have a specific gravity of about 1.2 kg/m3. The densest are ferruginous bauxites with a specific gravity of 2.8 kg/m3.
Bauxite outwardly similar to clay, but in other characteristics it is strikingly different from it. So, for example, bauxite cannot be diluted in water and make a plastic mass, as is done with clay. This is due to the shape and mineralogical difference.
According to the mineral composition, bauxites are divided into boehmite, diaspore, hydroargillite and mixed, depending on the chemical form of the aluminum contained.
The richest deposits of bauxite:
Almost 90% of all valuable mineral deposits are located on the territory of 18 countries. This is due to the occurrence of lateritic crusts formed by the weathering of aluminosilicates over millennia in a hot and humid climate.
There are 6 huge deposits. In Guinea - almost 20 billion tons. In Australia, more than 7 billion tons. In Brazil, up to 6 billion tons. In Vietnam, 3 billion tons. In India, 2.5 billion tons. In Indonesia, 2 billion tons. On the territory of these countries 2/3 of the earth's bauxite reserves are concentrated.
On the territory of the Russian Federation, the found deposits are not classified as large, but are of great value for the production of aluminum in the country. Large deposits were found in the Boksitogorsk region near St. Petersburg. And the most pure and valuable deposit in Russia is the North Urals.

The magical and healing properties of bauxite

Bauxite little used for making amulets. Unless a very unusual shape catches your eye, your hands will reach out to make crafts out of it.

Earlier, in the 18th and 19th century, bauxite was used in settings made of precious metal, mostly silver, only because of the unusual red hue. There are few such decorations, they were not popular.

By therapeutic effect also found no value. The aluminum contained in the rock is present in the human body in scanty concentrations. In plants, it is present at the micron level.

The main value of bauxite is a raw material for aluminum production.

The very first large bauxite deposit in the Urals was named "Red Riding Hood".
The breed got its name from France. The first deposit was found in the province of Provence near the town of Bo or Boaks (Beaux).
There are 10 main industrial grades of the mineral, differing in alumina concentration and composition.
The oldest of the bauxites can be found in tropical countries. These "pebbles" were formed in the Cenozoic or Proterozoic.
The greatest contribution to the development of technologies for the production of aluminum from bauxite was made by Russian scientists: Bayer, Manoilov, Strokov, Lileev and Kuznetsov. According to the Bayer method, discovered at the end of the 19th century, alumina is still being produced.

It might be useful to read: