Magnesium is a light metal. Magnesium

History of magnesium

Magnesium in the form of a metal was first obtained by Humphry Davy in 1808. An English chemist conducted an electrolysis process between a wet mixture of white magnesia and mercury oxide, resulting in an alloy of mercury with an unknown metal (amalgam). After the distillation of mercury, Davy received a new substance - metal powder, which was named magnesium(calorizer) . Two decades later, in 1828, the Frenchman A. Bussy received pure metallic magnesium.

Magnesium is an element of the main subgroup II of group III of the period periodic system chemical elements D.I. Mendeleev, has an atomic number of 12 and an atomic mass of 24.305. The accepted designation is mg(from Latin Magnesium).

Being in nature

According to the amount of content earth's crust magnesium ranks 8th among minerals, it is very common. Natural sources of magnesium are sea water, fossil mineral deposits and brines.

Magnesium is a light and malleable metal, its color is silvery white with a distinct metallic sheen. In the normal state, it is covered with a magnesium oxide film, which can be destroyed by heating the metal to 600-650 ° C. Magnesium burns with a dazzling white flame and forms magnesium oxide and nitride.

daily requirement for magnesium

The daily requirement for magnesium depends on the age, sex and physical condition of the person. For a healthy adult is 400 to 500 mg.

Food products contain different amounts of magnesium, we will arrange them in descending order of the content of a useful microelement:

• cereals ( and )
• dairy products, fish,

Magnesium absorption

The absorption of organic magnesium compounds mainly occurs in the duodenum and large intestine, with excessive use of caffeine, alcohol, and the body loses a significant part of magnesium in the urine.

Interaction with others

The balance between and magnesium is important for the body, because it is these minerals that are responsible for the normal state of bone tissue and teeth. In pharmacy vitamin-mineral complexes, the amount of calcium and magnesium is contained in optimal quantities.

Lack of magnesium in the body can cause kidney disease, indigestion, taking diuretics and some contraceptives, excessive addiction to alcohol and caffeine. Signs of magnesium deficiency are insomnia, irritability, dizziness, palpitations and jumps in blood pressure, frequent headaches, fatigue, flickering dots before the eyes, convulsions, muscle spasms, hair loss.

Signs of excess magnesium

Signs of excess magnesium are:

• diarrhea, nausea, vomiting
• drowsiness, slow heart rate
• coordination disorders, speech
• drying of mucous membranes (in the mouth and nose).

Magnesium is important for the efficient functioning of nerves and muscles and is essential for converting blood sugar into energy. Magnesium maintains healthy teeth, helps prevent deposits, kidney stones and gallbladder brings relief from indigestion. The human body contains approximately 21 g of magnesium.

Magnesium normalizes the activity of the cardiovascular and endocrine systems body, brain function, assists in the elimination of toxins and heavy metals.

The use of magnesium in life

Magnesium compounds (alloys) are used in aircraft and automotive manufacturing because of the strength and lightness of magnesium alloys. Magnesium is used as a chemical current source, in medicine, military affairs, and in photography.

Magnesium- this is an alkaline earth ductile metal of silver-white color (see photo). V periodic table Mendeleev is designated as Mg - from lat. magnesium. This was the name of the city in Asia, in the area of ​​​​which deposits of magnesite were discovered. At the end of the 17th century in England, salt with a bitter taste was mined from mineral water, which has a laxative effect. She was given the name Epsom salt. It contains magnesium. And in its pure form, it was already isolated in 1808, in the same England, by Sir Humphrey Davy.

In nature, it is found in very large quantities in the earth's crust in the form of minerals (dolomite, brucite and magnesite), in sea ​​water and salt lakes.

There is an opinion that chemical composition human body similar to the composition of the oceans. Accordingly, magnesium takes an active part in the biochemical reactions of any living organism.

The action of magnesium, its role and functions in the body

The action of the trace element is to participate in the metabolism of the body, and therefore, magnesium is one of the main elements of life. It activates the work of more than three hundred enzymes and B vitamins, participates in carbohydrate, protein and lipid metabolism.

Magnesium is called the "metal of life", because without its action, that is, without the functions that it performs in the body, many physiological processes will become impossible. And, first of all, such important ones as the functioning of the nervous and muscle tissues. For these properties, for all biologists, magnesium is on a par with oxygen, carbon, nitrogen and hydrogen - the most important elements in all living organisms.

Thanks to the action of magnesium, the body's thermoregulation occurs, the exchange of sodium, calcium, phosphorus and vitamin C. Its active form is positive ions, which form organic compounds. The same ions regulate the functioning of the nervous tissue and muscles, and at the cellular level controls the work of the potassium-sodium pump.

Most a large number of trace element accumulates in the bones, muscles, liver and tissues of the nervous system. It is not synthesized in the body, so its sources are food, salt and water. Having had a beneficial effect, magnesium is removed by the waste products of the intestine.

Magnesium plays a very important role in the body, because it alone controls all the work of cells - protein formation, metabolism, division and purification. This trace element is vital for all immune processes; in cases of allergies, stress, inflammation, it acts as an anti-toxic and anti-anaphylactic factor.

Magnesium is strong medicine from many diseases: myocardial infarction, nervous diseases, sclerosis, leukemia and other oncological diseases.

In combination with vitamin B6, it synthesizes lecithin, an amino acid that regulates the amount of cholesterol. And in this way magnesium affects the heart and blood vessels.

So, let's summarize the effects of magnesium on the body:

Daily rate - what is the body's need for an element?

The daily norm of a trace element averages 400 mg, or rather, it is calculated in the proportion of 0.05% of the total body weight. So, for children, the norm will be 200 mg, for pregnant and lactating women - 450-500 mg, and for people undergoing prolonged physical exertion or training, the need increases to 600 mg.

Magnesium deficiency in the body - symptoms and causes of deficiency

The lack of a microelement in the body leads to a wide variety of symptoms that many may mistake for the consequences of a disease.

There is a saying: “We are what we eat”. After all, it turns out that by changing our diet a little in one direction or another, we can shift the balance of substances in the body, harming or benefiting it. In the case of magnesium, this is the surest policy.

Symptoms of micronutrient deficiency:

Quite a bit of? One consolation is that they do not appear at the same time, but even one by one they can cause discomfort. And first of all, it is still worth checking the level of magnesium in the blood, and other elements, before taking a narrowly targeted treatment for any disease. The medicine may even be harmful.

By the way, women are more difficult to tolerate a lack of magnesium, which is associated with physiological and hormonal characteristics. It is precisely with the deficiency of this element that PMS symptoms- irritability, swelling, painful phenomena.

For women, the fact that magnesium is not the last element in the synthesis of collagen, a protein that is the basis of skin beauty and tendon elasticity, will also be important.

Deficiency can be caused by malnutrition, vitamin D deficiency, alcohol and drug addiction, pancreatitis and parathyroid malfunctions, and the use of hormonal drugs.

Even more real causes of magnesium deficiency in modern world can be called increased physical and mental stress, frequent stress, "famous" fast food. And if you dig deeper, it turns out that our lands are already very depleted in intensive crops, metals, organic fertilizers and industrial toxic waste. According to the results of research by the World Health Organization, the content of minerals and useful substances in products of plant origin decreased by 10-20 times.

There is an interesting observation that in cities with hard tap water with a predominance of calcium, people's health is in better condition than with soft drinking water. The residents have a calmer heart rhythm, less cholesterol in the vessels, less hypo- and hypertensive patients. Moreover, in areas with high content magnesium in soil and water - a record low level of oncological diseases.

By the way, residents of cities, especially megacities, live in a constant state of stress, in which the bulk of magnesium simply burns out, and this creates a chain reaction that develops even more stress. Those. magnesium is consumed and thus causes an even greater shortage. This state also causes large energy losses.

Magnesium deficiency in children

It often seems to parents that the more the child is busy with studies and additional electives, the better for him. And few people think that the school itself, sports sections and various circles can quickly deplete nervous system and create magnesium deficiency.

It is worth paying attention to symptoms such as fatigue, and, accordingly, problems with sleep and concentration, lethargy, whims, and convulsions. All this can be a sign of a micronutrient deficiency.

Excess magnesium - symptoms

In relation to the human body, it is very important to observe the measure. With regard to magnesium, as a trace element, the principle “the more the better” is not the most the best way. Because too much of it is as harmful as too little. The first signs are drowsiness, lethargy and depression. This is due to inhibition of calcium absorption by excess magnesium, which causes the effect of anesthesia.

The heart rate slows down, blood pressure decreases, thirst, vomiting, muscle weakness - these are the symptoms of magnesium intoxication.

And the reasons are: kidney failure, dehydration, an overdose of drugs containing magnesium (especially when administered intravenously), heat treatment and food preservation.

What food sources does it contain?

Magnesium in food is a component of any food chain. Those. any food that has not been heat treated can be called a carrier of magnesium, albeit in varying amounts. The richest in magnesium are unprocessed cereals (processing "kills" up to 80% of the element), nuts and beans. Also a good source is drinking water provided that it contains a lot of calcium.

Other food sources are sesame, greens, spinach, cereals, milk and dairy products, seafood, beef, Rye bread, dried fruits (dried apricots, figs).

It will also be useful to take magnesium preparations, but they should be taken only after consulting a doctor, who will determine the need for admission and dosage. Although often it is enough to change the principles of nutrition.

Supplements in combination with orotic acid should be called the most effective, they will be useful for hypertensive patients taking diuretics.

An excess of magnesium is very difficult to obtain due to the fact that the foods in our diet are most often initially poor in magnesium, thanks to modern "technologies".

Interaction with other substances

Interacting with other substances, magnesium has two polar actions: it either complements or contradicts. So, for example, vitamin B6 helps it to be absorbed, and calcium prevents absorption in the gastrointestinal tract (the optimal ratio of calcium to magnesium is 2: 1).

Magnesium also reduces the effectiveness of tetracycline antibiotics, iron preparations and anticoagulants, so doctors recommend observing at least a three-hour interval between their doses.

But fats and fibrous foods reduce the useful qualities of the element, forming indigestible salts.

When you receive folic acid and vitamin D3 increases the activity of enzymes and calcium, and hence the need for magnesium.

Vitamins A, B6, C, D, E and phosphorus in adequate amounts help the microelement to assimilate well.

A large amount of sugar causes an increase in the excretion of magnesium in the urine, due to insulin metabolism, as well as a high-protein diet affects the body, which constantly needs new and high-quality building materials (athletes, pregnant and lactating women).

Magnesium deficiency is caused by taking digitalis, a diuretic (furosemide).

Do not forget about the advice of specialists in order to avoid health problems.

Indications for appointment

Indications for the appointment of a microelement in the form of medicines:

• magnesium deficiency;
• convulsions, fatigue;
• psychological and emotional instability, sleep problems;
• tachycardia, disorders of the gastrointestinal tract;
• the threat of premature birth;
• epilepsy.

Magnesium was first discovered in the region of Thessaly, Greece and named Magnesia. It is the third most abundant metallic element in the earth's crust, but is rarely found in pure form due to the fact that it easily forms bonds with other elements. Magnesium metal was first obtained from ore in 1808 in small quantities by Sir Humphry Davy, and industrial production first started in 1886 in Germany.

Magnesium is the lightest of all commonly used structural materials with a density of 1.7 g/cm3 (106.13 lb/cu.ft.), about one-third lighter than aluminum and titanium, and one-fourth the density of steel. Despite this advantage, primary magnesium production in 2012 was 905 kt, just 2.5% of primary aluminum production (45.2 mt) and 0.06% of raw steel production (1546 mt). However, the volume of magnesium production is higher than that of titanium (211 thousand tons).

Small additions of magnesium to aluminum give fire resistance and strength. The proximity of magnesium to sulfur makes it indispensable in the production of certain grades of raw steel. With the help of magnesium, titanium metal is also restored from titanium tetrachloride in the Kroll process, and very high-quality grades of cast iron are also obtained. Together, these four areas accounted for 61% of magnesium consumption in 2012. Thus, despite its relative status as a minnow in the material mix, magnesium plays a central role in the manufacture and use of competing metal products.

Magnesium supplies

World primary magnesium production, according to Roskill, increased from 499 thousand tons in 2002 to 905 thousand tons in 2012, at a compound annual growth rate (CAGR) of 6.1%. The production of primary magnesium metal is limited to ten countries.

China continues to dominate the production of primary magnesium metal. The country produced more than 730 thousand tons of metal in 2012 and accounted for more than 75% of the total supply this year. In China, however, there has been a shift in production. The abundant and cheap gas as a by-product of coke production has prompted magnesium producers to turn their attention to Shaanxi province in search of higher profits. This has forced some traditional magnesium provinces to struggle with competitors, and in general, the Chinese magnesium industry has a capacity utilization rate of barely more than 50%. In addition, there has been industrial consolidation in China and eight Chinese manufacturers are now in the top 10 global manufacturers.

Despite recent efforts by the Chinese government to consolidate the industry, most of China's manufacturing capacity is still scattered in relatively small factories, and consolidation is mainly taking place in corporate level. Eight Chinese companies are in the top 10 global suppliers in terms of capacity, which for each exceeds 50 thousand tons per year, although only five of them produced more than 30 thousand tons in 2011, and one closed in 2012.

The number of companies with capacities below 50kt, and production well below 30kt, is not known, but Roskill estimates the number is around 50. Together, these small plants accounted for about a third of global capacity in 2012.

Source: "Metal Magnesium: Global Industrial Markets and Prospects 2012", Roskill Information Services Ltd.

Despite several plant shutdowns in advance of the 2008/09 downturn, especially in Canada, production in the US, Russia and Israel has since increased, albeit largely meeting demand from the growing titanium metal industry. Secondary magnesium production is more evenly distributed around the world, where the US is still the number one recycler. New primary magnesium plants were opened in Malaysia and South Korea in 2010, with Iran due to follow suit in 2013. The expected launch of the Qinghai Salt Lake electrolytic plant in China, with a capacity of 100 thousand tons per year, may also change the balance of power in China in the short term.

The main producers of primary magnesium outside of China are VSMPO-Avisma and the Solikamsk magnesium plant in Russia; US Magnesium in the US; Dead Sea Magnesium in Israel; Ust-Kamenogorsk titanium and magnesium plant in Kazakhstan; Rima Industrial in Brazil; CVM Minerals in Malaysia; Magnohrom in Serbia; and POSCO in South Korea.

Recycled magnesium from recycled magnesium alloys, and as a component of recycled aluminum alloys, is an important source of supply, particularly in the US, where it accounts for about half of the total supply. It is of much lesser importance elsewhere. Global capacity and production of secondary magnesium (excluding aluminum alloys, which form a feedback loop) are estimated by Roskill at more than 200 ktpa, with about 40% of the capacity concentrated in the US.

Most of the international trade in magnesium is exports from China, which accounted for half of the exports of raw magnesium (99.8% of Mg exports of raw magnesium in 2012. This material is mainly imported by Canada, Japan and Europe. The American market is protected from Chinese imports by high anti-dumping duties, and magnesium is supplied to the country from Israel, or it is domestic primary and secondary production.According to the Global Trade Atlas, analyzed by Roskill, international trade raw magnesium fell from about 500 thousand tons in 2007 to 305 thousand tons in 2009, rose to 480 thousand tons in 2011, but fell slightly in 2012.

About 50,000 tons of waste and scrap were sold in 2012 (compared to 62,000 tons in 2007), and this is mainly exports from Canada, Germany and Austria and imports to the USA, Czech Republic and Hungary. In addition, approximately 110 kt were sold in 2012 in the form of sawdust, shavings, granules and powder, with mainly exports from China and imports to Germany, Turkey and Canada. Finally, 37 thousand tons forged products were sold in 2012 (compared to 46 thousand tons in 2011), and these are mainly exports from China, Austria and Germany, and imports to Taiwan, New Zealand and Great Britain.

Demand for magnesium

The global apparent consumption (production + import - export) of magnesium reached 1,050 kt in 2007, a CAGR of 8% from 630 kt consumed in 2001. Primary magnesium metal consumption declined by 7% in 2008 and another 15% in 2009, falling below 690 kt, as the global economic crisis led to a significant decline in demand for magnesium-containing products.

However, the market recovered, surpassing 2007 levels in 2011 and showing a new demand peak in 2012. Recycling of magnesium further increased consumption, with total magnesium consumption exceeding 1 million tons in 2007 and 1.1 million tons in 2012.

China dominates world consumption with 340 thousand tons in 2012, 33% of the total. Other major markets for magnesium are North America(23% of world consumption) and Europe (18%). Russia and Japan are also large consumers, together accounting for 12%.

Historically, it has been aluminum alloys are the main uses of magnesium worldwide, although in 2012 the consumption of magnesium in this end-use area and the volume of magnesium consumption in die casting alloys became equal, with each area accounting for about 365 thousand tons, or 33% of the total consumption volume. The packaging industry is the largest market for magnesium in aluminum alloys, followed by transportation, construction and consumer durables.

The automotive industry is by far the largest consumer of cast magnesium components. Magnesium alloy injection molding is used for housings, assemblies, brackets and other components for all layers of auto Vehicle. The average magnesium application per vehicle in 2012 was 2.3 kg, with some models reaching up to 26 kg. Magnesium is used in the manufacture of molded housings for communication devices (for example, mobile phones and smartphones), laptops, tablet computers and other electronic equipment. This is the second largest use of cast magnesium after automobiles.

The production of titanium sponge (i.e. raw titanium metal) was the third largest consumption of magnesium, accounting for about 123 kt or 11% of total global consumption in 2012, while desulfurization was the fourth largest use, with 119 thousand tons in 2012. The use of magnesium in steelmaking has decreased in last years, due to the global economic crisis and, as a result, a slowdown in the growth (or decline) of steel production in many countries. On average, around 50 g/t of steel is used worldwide.

Source: "Metal Magnesium: Global Industrial Markets and Outlook 2012", Roskill Information Services Ltd.

Magnesium is also used in other applications, such as as a spheroidizing modifier for cast iron and as cathodic protection, a method of preventing corrosion by forcing all surfaces of a metal structure to be cathodes through the provision of active metal external anodes. Roskill estimates that magnesium use for these two applications was in the order of 65 kt and 60 kt in 2012.

While growth in auto production in some regions has boosted consumption since the 2008/09 slump, the market has been somewhat dampened by lower European vehicle deliveries. However, as a result of emission reduction pressures, growth in the use of magnesium in transportation continues to outpace the use of the metal in traditional materials such as steel, and the injection molding market is projected to grow at 6-7% per annum through 2017. . In aluminum alloys, magnesium is used predominantly in packaging and this market continues to show strong expansion due to economic growth in developing countries.

Lighter car weights and China boost magnesium demand

Roskill estimates that magnesium consumption reached a new peak in 2012, at 1.1 million tons, with demand growing at 5.5% per year over the past decade. Die casting and aluminum alloys remain the largest magnesium consuming industries, each accounting for a third of total consumption. The transport industry is the largest consumer of castings and the second largest consumer of metal, after aluminium-magnesium alloys in packages.

The magnesium industry is benefiting from growth in automotive production, led by China, as well as higher magnesium consumption in vehicles as manufacturers strive to meet government-imposed emission reduction targets and rising fuel costs affect consumer buying trends. Continued weight loss efforts mean magnesium consumption will continue to grow at a rate of at least 5.0% per year until 2017. The use of magnesium in cast parts is likely to grow faster, at 6.5% per annum, but the market will be constrained by lower growth in steel desulfurization and spheroidizing annealing.

Growth in Chinese consumption more than offset a slight drop in the rest of the world since 2007, with Asia accounting for 43% of global consumption in 2012, up from 35% five years ago. North America accounted for 20% of consumption and Europe for 15%. India and South Korea have shown solid consumption growth over the past five years, but on a low base in volume terms, while consumption in Russia has almost doubled due to increased titanium production. Asia, more specifically China, will continue to show the highest growth in magnesium demand on a regional basis until 2017.

China dominates global supply, but domestic competition is often overlooked

Primary magnesium production continues to be dominated by China, which, according to Roskill, accounted for 75% of global production in 2012. Russia and the US together represent another 16%, followed by smaller producers - Israel, Kazakhstan, Brazil, Serbia and Ukraine. Malaysia and South Korea have entered the market in recent years, albeit on a small scale, but this and some limited expansion of existing operations have done little to dampen China's growing share. Secondary magnesium, whose production in 2012 amounted to 211 thousand tons, comes mainly from casting scrap. North America is the main source of recycled magnesium followed by Europe as these regions continue to be major consumers of magnesium based products.

China's leading position in primary magnesium production reflects the domestic availability and low cost of ferrosilicon and energy (in the form of coal, coke and electricity), which are the main components of the energy-intensive, thermal pidgin metal production process. However, faced with rising energy prices and government pressure to reduce emissions, Chinese magnesium companies have invested in process optimization to reduce costs. Although China is often viewed as a single entity in the case of magnesium supplies, competition has also increased strongly in the domestic industry due to the recent increase in the availability of coke gas, as a result of the relocation of domestic production to Shaanxi, which limited growth in Shanxi and Ningxia, and in a result of losses in production elsewhere.

The low capital cost of transitioning from bench process plants means that moving domestic production from province to province is relatively easy, but results in a significant increase in capacity. Roskill estimates Chinese primary capacity at 1.3Mt, but of this only 0.8-0.9Mt is in use; the remaining capacities are mothballed or uneconomical. This trend led to the closure of at least one major manufacturer in China in 2012, as well as industry consolidation.

Despite price competitiveness and overcapacity in China, a new 100,000-tonne electrolytic plant in Qinghai, due to open soon, could further change the domestic landscape. Several companies using new processes or variations from existing electrolytic and thermal methods also continue to explore the possibility of primary magnesium production in other countries, especially in Australia and Canada. However, until these projects can compete with Chinese production costs and be economically viable at current and projected magnesium prices of $2500-3000/t, China is likely to gradually increase its market share as demand grows.

magnesium prices

There are no magnesium trading platforms in the world, and therefore, in most cases, the terms of contracts are negotiated directly between producers and consumers. However, a large amount of Chinese material is traded on a spot basis by traders and Chinese manufacturers to the European, Japanese and domestic market. The main market prices for magnesium, therefore, are Chinese domestic and export prices for metal with a purity of 99.8% Mg, and European prices for the ex-Rotterdam warehouse. Some supply of magnesium occurs outside of China's trade with other countries, but it forms a smaller part of the overall open market.

Rising demand, in particular in China, led to rapid price increases in the fourth quarter of 2007 and the first half of 2008. At its peak in the first half of 2008, prices rose above $6,000/t FOB China for 99.8% purity magnesium ingot. Prices retreated to lower levels in subsequent years, driven by shrinking demand due to the global economic crisis, although still higher than before the 2007/08 peak. The abolition of the 10% export duty on Chinese shipments at the end of 2012 caused a ripple effect on both European prices and Chinese export prices, driving prices of $2500-3000/t FOB China since 2013. Due to anti-dumping duties on Chinese material, magnesium is sold at a premium in the US.

Magnesium is an element of the main subgroup of the second group, the third period of the periodic system of chemical elements, with atomic number 12. It is denoted by the symbol Mg (lat. Magnesium). The simple substance magnesium (CAS number: 7439-95-4) is a light, malleable silver-white metal. Moderately common in nature. During combustion, a large amount of light and heat is released.

origin of name

In 1695, salt was isolated from the mineral water of the Epsom Spring in England, which had a bitter taste and laxative effect. Apothecaries called it bitter salt, as well as English, or Epsom salt. The mineral epsomite has the composition MgSO 4 7H 2 O. The Latin name of the element comes from the name ancient city Magnesia in Asia Minor, in the vicinity of which there are deposits of the mineral magnesite.
It was first isolated in its pure form by Sir Humphry Davy in 1808.

Receipt

The usual industrial method for obtaining metallic magnesium is the electrolysis of a mixture of anhydrous magnesium chlorides MgCl 2 (bischofite), sodium NaCl and potassium KCl. Magnesium chloride undergoes electrochemical reduction in the melt:
MgCl 2 (electrolysis) \u003d Mg + Cl 2.

The molten metal is periodically taken from the electrolysis bath, and new portions of magnesium-containing raw materials are added to it. Since the magnesium obtained in this way contains a relatively large amount (about 0.1%) of impurities, if necessary, "raw" magnesium is subjected to additional purification. For this purpose, electrolytic refining, vacuum remelting with the use of special additives - fluxes, which “take away” impurities from magnesium or distillation (sublimation) of the metal in vacuum are used. The purity of refined magnesium reaches 99.999% and higher.
Another method for obtaining magnesium has also been developed - thermal. In this case, silicon or coke is used to reduce magnesium oxide at high temperature:
MgO + C = Mg + CO

The use of silicon makes it possible to obtain magnesium from raw materials such as CaCO 3 ·MgCO 3 dolomite without preliminary separation of magnesium and calcium. With the participation of dolomite, reactions occur:
CaCO 3 MgCO 3 \u003d CaO + MgO + 2CO 2,
2MgO + CaO + Si = CaSiO 3 + 2Mg.

The advantage of the thermal process is that it makes it possible to obtain higher purity magnesium. To obtain magnesium, not only mineral raw materials are used, but also sea water.

Physical properties

Magnesium is a silver-white metal with a hexagonal lattice, space group P 6 3 /mmc. At normal conditions the magnesium surface is covered with a strong protective film of magnesium oxide MgO, which is destroyed when heated in air to about 600 ° C, after which the metal burns with a dazzling white flame to form magnesium oxide and nitride Mg 3 N 2 . The density of magnesium at 20 ° C is 1.737 g / cm³, the melting point of the metal is t melt = 651 ° C, the boiling point is t bp = 1103 ° C, the thermal conductivity at 20 ° C is 156 W / (m K). Magnesium of high purity is ductile, well pressed, rolled and machinable.

Chemical properties

A mixture of powdered magnesium with potassium permanganate KMnO 4 is an explosive.
Hot magnesium reacts with water:
Mg (decay) + H 2 O \u003d MgO + H 2;

Alkalis do not act on magnesium, it dissolves easily in acids with the release of hydrogen:
Mg + 2HCl \u003d MgCl 2 + H 2;

When heated in air, magnesium burns to form an oxide; a small amount of nitride can also form with nitrogen:
2Mg + O 2 \u003d 2MgO;
3Mg + N 2 \u003d Mg 3 N 2

The predominant industrial method for obtaining magnesium is the electrolysis of a melt of a mixture of MgCl 2

MgCl 2 Mg 2+ 2Cl -

Mg 2+ +2e Mg 0 2Cl - -2e Cl 2 0

2MgCl 2 2Mg+ 2Cl 2

melt

in anhydrous MgCl 2 , KCl, NaCl. To obtain the melt, dehydrated carnallite or bimophyte is used, as well as MgCl 2 obtained by chlorination of MgO or as a waste in the production of Ti.

Electrolysis temperature 700-720 o C, graphite anodes, steel cathodes. The content of MgCl 2 in the melt is 5-8%, with a decrease in concentration to 4%, the output of magnesium by current decreases, with an increase in the concentration of MgCl 2 above 8%, the consumption of electricity increases. To ensure the optimal content of MgCl 2 periodically select part of the spent electrolyte and add fresh carnallite or MgCl 2 . Liquid magnesium floats to the surface of the electrolyte, from where it is taken with a vacuum ladle. Extracted magnesium raw contains 0.1% impurities. To remove non-metallic impurities, magnesium is melted down with fluxes - chlorides or fluorides K, Ba, Na, Mg. Deep cleaning is carried out by vacuum distillation, zone melting, electrolytic refining. The result is magnesium with a purity of 99.999%.

In addition to magnesium, electrolysis also produces Cl 2 . In thermal methods for producing magnesium, magnesite or dolomite is used as a raw material, from which MgO is obtained by calcination. 2Mg+O 2 =2MgO. In retort or rotary furnaces with graphite or coal heaters, oxide is reduced to metal with silicon (siliconothermal method) or CaC 2 (carbide thermal method) at 1280-1300 ° C, or carbon (carbothermal method) at temperatures above 2100 ° C. In the carbothermic method ( MgO+C Mg+CO) the resulting mixture of CO and magnesium vapor is quickly cooled when leaving the furnace with an inert gas to prevent a back reaction with magnesium.

properties of magnesium.

Physical properties of magnesium.

Magnesium is a silvery-white lustrous metal, relatively soft and ductile, a good conductor of heat and electricity. Almost 5 times lighter than copper, 4.5 times lighter than iron; even aluminum is 1.5 times heavier than magnesium. Magnesium melts at a temperature of 651 ° C, but under normal conditions it is quite difficult to melt it: heated in air to 550 ° C, it flares up and instantly burns out with a dazzlingly bright flame. A strip of magnesium foil can be easily set on fire with an ordinary match, and in an atmosphere of chlorine, magnesium ignites spontaneously even at room temperature. When burning magnesium, a large amount of ultraviolet rays and heat is released - to heat a glass of ice water to a boil, you need to burn only 4 g of magnesium.

Magnesium is located in the main subgroups of the second group of the D.I. Periodic Table of Elements. Mendeleev. Its serial number is 12, atomic weight is 24.312. The electronic configuration of the magnesium atom in the unexcited state is 1S 2 2S 2 P 6 3S 2 ; the electrons of the outer layer are valence, in accordance with this, magnesium exhibits valency II. In close connection with the structure of the electron shells of the magnesium atom is its reactivity. Due to the presence of only two electrons in the outer shell, the magnesium atom tends to easily donate them to obtain a stable eight-electron configuration; therefore, magnesium is chemically very active.

Magnesium oxidizes in air, but the resulting oxide film protects the metal from further oxidation. The normal electronic potential of magnesium in an acidic environment is -2.37V, in an alkaline - 2.69V. In dilute acids, magnesium dissolves already in the cold. In hydrofluoric acid, it is insoluble due to the formation of a film of MgF 2 fluoride, which is sparingly soluble in water; almost insoluble in concentrated sulfuric acid. Magnesium dissolves easily under the action of solutions of ammonium salts. Alkali solutions do not work on it. Magnesium enters laboratories in the form of powder or tapes. If you set fire to a magnesium tape, it quickly burns out with a blinding flash, developing a high temperature. Magnesium flashes are used in photography, in the manufacture of lighting rockets. The boiling point of magnesium is 1107 o C, density = 1.74 g / cm 3, atomic radius 1.60 NM.

Chemical properties of magnesium.

The chemical properties of magnesium are quite peculiar. It easily removes oxygen and chlorine from most elements, is not afraid of caustic alkalis, soda, kerosene, gasoline and mineral oils. WITH cold water magnesium almost does not interact, but when heated, it decomposes with the release of hydrogen. In this respect, it occupies an intermediate position between beryllium, which generally does not react with water, and calcium, which easily interacts with it. The reaction is especially intense with water vapor heated above 380 ° C:

Mg 0 (tv) + H 2 + O (gas) Mg +2 O (tv) + H 2 0 (gas).

Since the product of this reaction is hydrogen, it is clear that extinguishing burning magnesium with water is unacceptable: an explosive mixture of hydrogen and oxygen can form and explode. It is impossible to put out burning magnesium and carbon dioxide: magnesium restores it to free carbon

2Mg 0 +C +4 O 2 2Mg +2 O+C 0 ,

You can stop the access of oxygen to burning magnesium by filling it with sand, although magnesium interacts with silicon (IV) oxide, but with much less heat release:

2Mg 0 + Si +4 O 2 \u003d 2Mg +2 O + Si 0

this determines the possibility of using sand to extinguish silicon. The danger of magnesium igniting during intense heating is one of the reasons why its use as an engineering material is limited.

In the electrochemical series of voltages, magnesium is much to the left of hydrogen and actively reacts with dilute acids to form salts. In these reactions, magnesium has features. It does not dissolve in hydrofluoric, concentrated sulfuric acid, and in a mixture of sulfuric and nitric acids, which dissolves other metals almost as efficiently as "aqua regia" (a mixture of HCl and HNO 3). The resistance of magnesium to dissolution in hydrofluoric acid is explained simply: the surface of magnesium is covered with a film of magnesium fluoride MgF 2 insoluble in hydrofluoric acid. The resistance of magnesium to sufficiently concentrated sulfuric acid and its mixture with nitric acid is more difficult to explain, although in this case the reason lies in the passivation of the magnesium surface. Magnesium practically does not interact with solutions of alkalis and ammonium hydroxide. But with solutions of ammonium salts, the reaction, although slowly, but occurs:

2NH + 4 + Mg \u003d Mg 2+ + 2NH 3 + H 2

This reaction is not surprising. This reaction is essentially the same as the reaction of displacement of hydrogen from acids by metals. In one definition, an acid is a substance that dissociates to form hydrogen ions. This is how the NH4 ion can also dissociate:

NH 4 + NH 3 +H +

Mg 0 + 2HCl \u003d Mg +2 Cl 2 + H 0 2

2H + + Mg Mg 2+ + H 0 2

When magnesium is heated in a halogen atmosphere, ignition and the formation of halide salts occur.

The cause of ignition is a very large heat release, as in the case of the reaction of magnesium with oxygen. Thus, in the formation of 1 mol of magnesium chloride from magnesium and chlorine, 642 kJ is released. When heated, magnesium combines with sulfur (MgS), and with nitrogen (Mg 3 N 2). At high blood pressure and heated with hydrogen, magnesium forms magnesium hydride

Mg 0 + H 2 0 Mg +2 H 2 -.

The high affinity of magnesium to chlorine made it possible to create a new metallurgical production - "magnesium" - the production of metals as a result of the reaction

MeCln + 0.5nMg \u003d Me + 0.5nMgCl 2

this method produces metals that play a very important role in modern technology - zirconium, chromium, thorium, beryllium. Lightweight and durable "space age metal" - almost all titanium is obtained in this way.

The essence of production is as follows: in the production of metallic magnesium by electrolysis of a melt of magnesium chloride, chlorine is formed as a by-product. This chlorine is used to produce titanium (IV) chloride TiCl 4 , which is reduced by magnesium to metallic titanium

Ti +4 Cl 4 + 2Mg 0 Ti 0 +2Mg +2 Cl 2

The resulting magnesium chloride is reused for the production of magnesium, etc. Based on these reactions, titanium-magnesium plants work. Along with titanium and magnesium, other products are also obtained, such as Bertolet's salt KClO 3 , chlorine, bromine and products - fiberboard and xylitic plates, which will be discussed below. In such an integrated production, the degree of use of raw materials, the profitability of production is high, and the mass of waste is not large, which is especially important for protecting the environment from pollution.