Antimony metal and it’s usage in industry

Antimony metal profile

Antimony is a chemical element with the symbol Sb and atomic number 51. Antimony is a gray porous metal and is mainly found as a mineral sulfide in nature. Antimony compounds have been known since ancient times and have been powdered for use in industries such as medicine and cosmetics.

Antimony is a chemical element Semimetallic . The metal type of antimony has a light silver color and is hard and brittle. Its non-metallic form is mainly in the form of a gray powder. This substance is sometimes found freely in nature. But it is usually obtained from the ores “stenbit” ( Sb₂S₃ ) and “valentinite” ( Sb₂O₃ ).

Antimony is a poor conductor of heat and electricity. It is stable in dry air and is not attacked by dilute or alkaline acids. The interesting thing about antimony and some of its alloys is that they expand when cooled.

High-purity antimony is used to make certain types of semiconductor devices, such as diodes and infrared detectors. By alloying this metal with lead, the durability of lead can be multiplied.

Antimony alloys are used in batteries, low friction metals, cables and many other products. The compounds of this element are also used to make anti-flame materials, paints, ceramic enamels, glass and pottery. The ancient Egyptians used the substance “astenite”, which contains antimony, as eyeliner.

Industrial methods for refining antimony are :

• to heat
• Reduction of carbon or direct reduction of etibenite with iron

The largest antimony producing countries

• China : Most of its production is from Xikuangshan mine in Hunan
• Russia
• Bolivia
• Australia
• South Africa
• Tajikistan
• Mexico
• America
• Iran

When does the discovery of antimony go back?

Unlike many metals, antimony has been used by humans for thousands of years. The ancient Egyptians used the metal in cosmetics and medicine about 5,000 years ago. Ancient Greek physicians prescribed its powders to treat skin disorders.

In the Middle Ages, metal antimony was a favorite of alchemists. According to some of the earliest metallurgical books in Europe, the earliest methods for isolating antimony metal were probably known by Italian chemists more than 600 years ago.

Antimony and its compounds were well known in the past, and there is a 5,000-year-old antimony metal vase in the Louvre Museum in Paris. Antimony sulfur (Sb₂S₃ ) is mentioned in Egyptian papyri from the 16th century BC. The black form of this pigment is naturally present as the mineral stenbite.

Another known pigment of this metal was the yellow lead antimony known in the Chaldean civilization, which was used in southern Iraq in the 6th and 7th centuries BC. This compound was found in the glaze of decorative bricks in Babylon. Antimony was widely used in the Middle Ages.

An overview of the properties of antimony metal

The most stable form of elemental antimony is a brittle, silver substance with a high metallic luster. Electrolyte deposition of antimony in certain conditions creates an unstable and amorphous form called “explosive antimony”. Because when bent or scratched, it gently explodes into a more stable metal shape.

There is also an amorphous black antimony produced by the sudden quenching of the vapor phase. A yellow form of the metal has also been observed due to the low temperature oxidation of stebin with the chemical formula SbH₃ in air or chlorine.

Metal antimony is not normally affected by air and humidity. But if the air is humid, it gradually oxidizes. Antimony is easily oxidized by sulfur and halogens when heated. When heated in air, it burns with a glowing blue flame to form white trioxide vapors with the chemical formula Sb₂O₃ . Antimony trioxide is soluble in both acids and alkalis.

The electronic structure of antimony is almost similar to arsenic and has three half-filled orbitals in its outermost shell. Therefore, it can form three covalent bonds and form oxidation states of +3 and -3. The electronegativity of antimony, like arsenic, is somewhat controversial. It is generally agreed that this parameter is lower in this element than arsenic. But it is not certain that it is less than phosphorus.

This element can act as an oxidizing agent and react with many metals. As a result, it forms antimonides that are generally similar to nitrides, phosphides, and arsenides. But they are also somewhat metal. The upgrade of one of the unpaired electrons to an external d orbital appears to occur more easily in antimony than in arsenic. Because antimony shows the oxidation state of 5+ in the formation of ” pentafluoride ” and ” pentachloride ” compounds.

Distribution and abundance of antimony

The abundance of antimony on Earth is about one-fifth that of arsenic. That is, on average, about one gram per ton of the earth’s crust is found. Cosmically, it is estimated that there is one antimony atom for every 5,000,000 silicon atoms.

Antimony has two stable isotopes that are approximately equal in abundance and are found in nature. The crime is one 121 and the other 123. Radioactive isotopes of this element have masses of 120, 122, 124, 125, 126, 127, 129 and 132, which are mainly produced artificially.

Very few deposits of pure antimony metal are found today. In fact, most of the abundance and distribution of antimony is in the form of more than 100 minerals. If you remember, we said that the most important ores are “Stebnite” (Sb₂S₃ ) and “Valentinite” (Sb₂O₃ ) ores . Small stenite deposits are found in Algeria , Bolivia , China , Mexico , Peru , South Africa , and parts of the Balkan Peninsula .

Other stones from which the production of antimony has economic value are :

• Cream ( 2Sb₂S₃ · Sb₂O₃ )
• Tetrahydrite Organifers ( (Cu,Fe)₁₂Sb₄S₁₃ )
• Livingstone ( HgSb₄S₇ )
• Jamsonite ( Pb₄FeSb₆S₁₄ )

Small amounts of antimony can also be recovered from the copper and lead production process. About half of the antimony produced is recycled from lead scrap alloys from old batteries. This element was added to older batteries to provide hardness.

How is antimony extracted?

High-grade (or enriched with antimony) stebite reacts directly with molten scrap iron to release antimony metal. This process takes place at a temperature of 500 to 600 degrees Celsius. Thus, in general, antimony can be obtained by converting stenbite to oxide, followed by reduction with carbon (coke).

The main chemical reactions that occur in this process are as follows :

Sb₂S₃ + 3Fe → 2Sb + 3FeS

2Sb₂S₃ + 3C → 4Sb + 3CO₂

Sodium sulfide solutions are an effective leaching agent to increase the concentration of stebenite. In fact, it is the electrolysis of these solutions that produces antimony. As is evident in the reactions, the sulfide is first converted to the oxide. The product is then cooked. Finally, the antimony is separated from the oxide by carbothermal reduction.

After further refining of the crude antimony, the resulting metal, called Regulus, is cast into a cake. Extraction of antimony from ore largely depends on the quality and composition of the ore. Most of the antimony produced is extracted as sulfide. Low grade ores can also be concentrated by flotation.

Antimony metal mines in Iran

The most important antimony mine in Iran is Sefid Abe mine.

This mine has been constructed at a distance of 300 km northwest of Zahedan in Sistan and Baluchestan province. The operator and holder of the exploitation license of this mine is “Iran Minerals Production Company”.

The definitive reserve of this mine, according to the exploitation license, is 4500 tons of antimony ore with a grade of 37%. However, according to the report on the revaluation of reserves, there have been reports of an increase in reserves from 5,000 to 25,000 tons.

The annual nominal extraction of ore based on the exploitation license at the time of setting up the mine and factory was equal to 500 tons of ore. With laboratory studies performed on antimony ingots, a product with a grade of 99.98% was obtained, which is equal to the world standard.

” Torbat Jam ” antimony mine is also the second most important mine of this metal in Iran.

This mine is located 45 km northwest of Torbat-e Jam in the village of Cheshmeh Johar. The area of ​​this mineral area is 10.3 square kilometers. The definitive reserve of this mine is 12,000 tons of antimony, its annual extraction rate is 1,500 tons and its type is antimony sulfide mineral in 25% carbonate bedrock.

In addition to the provinces of Sistan and Baluchestan and Khorasan Razavi provinces of Azerbaijan, East, West Azerbaijan, Ardebil, Kurdistan, Zanjan and of the traces of antimony detected.

Geological survey the entire range of the antimony reserves in the country are examined according to the organization at least more than  100 tons of antimony in the range of Kalat, Khorasan CHUBAK Razavi has discovered in the Red Mountain of Kashmar, in Arqach region and Negian region

While around Zahedan, there are many antimony reserves and to date, the minimum reserve area in the province has been identified, which is the largest antimony reserves in Iran. Therefore, according to the available information, it should be said: the antimony belt in the country starts from Torbat-e Jam and extends to Zahedan

Antimony usages

Antimony is a brittle metal and a weak conductor of heat and electricity. High-purity antimony is used to make semiconductor devices such as diodes and infrared detectors. Antimony is alloyed with lead to increase the durability of lead. Antimony alloys are also used in batteries, low friction metals and cable sheaths

Antimony compounds are used to make fire retardants, paints, ceramic enamels, glass and pottery. The largest use of antimony metal is as an alloy with lead, tin and lead antimony plates in lead acid batteries. The combination of lead and tin alloys with antimony improves their properties for soldering, pelleting, or simple arc welding

Antimony compounds are important additives for anti-chlorine and bromine materials that contain fire-resistant materials in many commercial and household products. A new application of antimony is its use in microelectronics

• Alloys and antimony compounds

About half of the antimony produced is used in metallurgical applications and is mainly used in alloys. Because some antimony alloys expand during solidification, they are valuable as a cast metal.

Expansion of the alloy will force the metal to fill small gaps in the casting molds. In addition, the presence of antimony in alloys containing lead and small amounts of tin increases the hardness of the alloy.

This element increases strength and hardness even if it is added in small amounts to metals such as lead. The alloys that are formed can be widely used in car battery panels, pellets, cable covers and chemical equipment such as tanks and pipes.

Antimony forms anti-friction alloys called babbitts that are used in machine bearing components. Along with tin, it also forms alloys such as brittle and pewter that are used for dishes.

This element is also used as a soldering alloy. Very pure types are used in semiconductor technology to prepare intermetallic compounds with indium, aluminum and gallium antimonide for diodes and infrared detectors.

Antimony compounds (especially trioxide) are widely used as fire retardants in paints, plastics, rubber, and textiles. Several other antimony compounds are used independently as pigments.

Tartar Emetic, an organic antimony salt, is used in the textile industry to help bind certain dyes to fabrics.

• Fire and flame retardants

One of the most common applications of antimony is trioxide use for flame retardant applications. This element is always used in conjunction with halogenated flame retardants. Of course, except for polymers containing halogens.

The inhibitory effect of antimony trioxide is due to the formation of halogenated antimony compounds. It reacts with hydrogen atoms, possibly oxygen atoms and OH radicals, eventually inhibiting fire.

The main markets for this type of fire retardant include furniture, children’s clothing, toys, airplanes, and car seat covers. Antimony inhibitors are also added to polyester resins in fiberglass composites for items such as light aircraft covers. Of course, it should be noted that this resin burns in the presence of an external flame. But when the flame is removed, it goes out and the burning does not continue.

• Biology and Medicine

Few applications for antimony have been reported in biology and medicine. Antimony and its compounds are used in several veterinary medicines such as “antivalin” and “thiomalate lithium antimony” as a skin emollient in ruminants. Antimony has a number of nutritional effects on keratinized tissues in animals.

Other antimony-based drugs, such as meglumine antimony , are also used as the drug of choice for the treatment of leishmaniasis in domestic animals. Historically, crushed antimony powder (kohl) has been applied to the eyes using a metal rod and seasoning.

Biological and toxic effects of antimony

Antimony and some of its compounds are very toxic. In fact, the use of antimony compounds for medicinal purposes was temporarily outlawed a few centuries ago because of the number of casualties it caused.

Tartar Emetic is one of the few compounds currently used in human medicine as an expectorant, stimulant, and stimulant. It should be noted that today this drug is gradually being replaced by a drug called Praziquantel. The maximum tolerable concentration of antimony dust in the air is approximately the same as that of arsenic, which is reported to be 0.5 mg per cubic meter.

People who work with antimony may be harmed by breathing in dust containing this element. Human antimony exposure can be achieved by breathing air, drinking water, and eating foods containing it. Breathing antimony, which is bound to hydrogen in the gas phase, will have many negative effects on health.

Prolonged exposure to relatively high concentrations of this element (9 mg per cubic meter of air) can irritate the eyes, skin and lungs. With continued contact, more serious health effects such as lung disease, heart problems, and. May occur.

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