What is metal zirconium, its properties.
Zirconium is not a very widely known metal, but its amazing properties make it irreplaceable in atomic power engineering, chemical sector, medicine and many other industries.
Zirconium is a silvery-grey metal with a yellowish tinge and a specific glance. It has high plastic properties and corrosion resistance. This is an element of the secondary subgroup of the fourth group of the fifth period of the Mendeleev’s Periodic Table, its atomic number is 40.
The German chemist Martin Heinrich Klaproth first identified zirconium in 1789. He analyzed a sample of the mineral hyacinth (jacinth) from the island of Sri Lanka.
Hyacinth containing zirconium has been known since ancient times as a gemstone due to its beautiful pale yellow-brown color, turning into smoky green, and its special glance. Hyacinth was considered a variety of topaz and ruby, closely related to them in its chemical composition.
The Swedish chemist Jöns Jakob Berzelius is credited with isolating zirconium in 1824.
Until the 20th century, the metal could not be obtained in pure form, but in 1925 (100 years after the first samples of the element were isolated!) scientists finally succeeded in obtaining zirconium free of all impurities. However, it did not find wide industrial use until the late 1940s. It was during those years that zirconium became an important technical material used in the nuclear industry.
Zirconium is often confused with the mineral zircon, which is zirconium silicate.
Since ancient times the mineral zircon, from which zirconium is obtained, has been used for making jewellery. It is believed that the word “zircon” originates from the Persian “zargun” which means “gold-like” or “golden stone.”
Zircon is used in the jewelry industry. It can have different colors and may be green, brown, black, yellow or sometimes red.
The color of zircon depends on the impurities in it. The impurities that color the stone are calcium, copper, iron, zinc, uranium, strontium, and titanium. Zircon also can contain rare-earth elements.
In its pure form zirconium has many properties that are similar to those of gold. It is:
- ductile;
- malleable;
- corrosion-resistant;
- heat-stable;
- paramagnetic.
Zirconium is ductile and therefore easily amenable to hot and cold processing (forging, rolling, stamping). The fragility of the metal can be caused by the presence of small amounts of dissolved nitrogen, oxygen, hydrogen and carbon.
Zirconium is a metal resistant to high temperatures. Its melting point is 1855о С, boiling point is 4409о С. Zirconium dioxide is one of the most not-easily-fusible substances on the Earth.
Brinell hardness number of zirconium is 640-670 MN/m². Oxygen has a strong influence on the hardness of zirconium, and at its concentration of 0.2% zirconium cannot undergo cold processing by pressure.
At a temperature of 200-400о С zirconium begins to slowly oxidize, becoming covered with a film of zirconium dioxide. Zirconium reacts with fluorine at normal temperatures, and at temperatures above 200°C it reacts with bromine, chlorine, and iodine.
Zirconium does not react with hydrochloric, sulfuric acid and with alkalis. At temperatures above 100°C, interaction with nitric acid takes place.
The metal is not affected by chlorinated and seawater. It preserves its high-quality properties at both low and high temperatures.
Raw materials for obtaining metallic zirconium
Zirconium cannot be found in its pure form in the earth’s crust, so it is obtained from ore concentrate or by melting zirconium waste.
Zirconium is mainly abundant in the lithosphere and is considered a trace element. In nature its compounds with oxygen are known in the form of silicates and oxides. There are 40 minerals in the earth’s crust that contain zirconium. The most common minerals in nature are zircon, baddeleyite and eudialyte; there are also various complex minerals.
The main zirconium-containing mineral is zircon, which is mainly found in granites and syenites, but also in other rock types such as coastal sands.
This mineral is scattered deep within the Earth and is not found in large deposits. It is most common in deposits in the USA, Australia, Brazil, India, and Russian Federation.
Explored reserves of zirconium minerals amount to 45 million tons, 27 million tons of which are in India, about 14 million tons in Australia, 11 million tons in South Africa, over 7 million tons in the USA. Total world resources exceed 60 million tons.
Ukraine has reserves of about 4 million tons of zirconium oxide.
The main producers of zirconium concentrate are six countries: Australia, South Africa, the USA, Mozambique, Senegal and Indonesia. Their total share in the world in 2020 was 87%, with Australia and South Africa providing almost 60%.
In Ginderson (North Carolina, USA) zircon crystals several centimeters long were found in pegmatites, and crystals with the weight of some kilograms were discovered in Madagascar.
The main producers of metallic zirconium today are: Australia, Indonesia, China and South Africa.
Metallic zirconium of nuclear purity is currently produced in the world by the following companies:
- APEVA NP (CEZUS+ZIRCOTUBE, being its part) (France);
- JSC “TVEL” (Russian Federation);
- Westinghouse (USA);
- GNF (USA + Japan);
- NFC (India).
In addition to these companies, other companies in Sweden, Great Britain, Canada, Argentina and China also produce zirconium products.
Five companies have a complete metallurgical cycle from zirconium concentrate to finished products: APEVA NP, JSC “TVEL”, Westinghouse, Teledyne Wah Chag as well as state company NFC (India).
Application of zirconium
Zirconium alloys have been widely used since the 30s of the twentieth century. Nowadays their areas of application are only extending.
Modern areas of application of zirconium and its alloys are as follows:
- atomic power engineering – for manufacture of fuel elements, assemblies and structures of nuclear reactors;
- metallurgy – as an alloying additive, which significantly increases mechanical properties of metals, making them almost unique;
- chemical industry – due to its extreme resistance to corrosion and many acids and alkalis;
- electrical industry – zirconium is a wonderful superconductor, can withstand loads of up to 100,000 A/cm2;
- machine-building industry – used as a structural material for manufacturing acid-resistant chemical reactors, pumps, fittings;
- aviation and space – used in jet engines and spacecraft parts; heat-resistant alloys, which are indispensable in aircraft and rocket engineering are alloyed with zirconium;
- zirconium compounds are used in ceramics, abrasives and lamp glow filaments;
- pyrotechnics – smokeless, bright fireworks are impossible without this metal;
- medicine – due to its biocompatibility and durability zirconium dioxide is used as a material for surgical and dental implants, pins, crowns;
- high chemical resistance allows for production of various dishware;
- jewelry industry – zirconium dioxide, also known as cubic zirconia, is a gemstone.
Cubic zirconia, a material synthesized from zirconium dioxide, can serve as a substitute for diamonds and other gemstones.
Cubic zirconias are crystals of the highest, cubic system. Their crystal grid has equal faces located at right angles. Cubic zirconias lend themselves well to gem-cutting and, in any frame, delight the eye with the perfection of their shapes.
The price of zirconium may vary depending on the type of product made. The price of zirconium on the world market ranges from US$100 to US$500 per 1 kg.
CONCLUSION
- Zirconium is a silvery-grey metal with a yellowish tinge and a specific glance. It has high ductility and good corrosion resistance.
- Zirconium is a metal resistant to high temperatures. Its melting point is 1855о С, boiling point is 4409о С.
- There are 40 minerals in the earth’s crust that contain zirconium. The most common minerals found in nature are zircon, baddeleyite, and eudialyte.
- For industrial zirconium production zirconium concentrates, containing 60-65% zirconium dioxide, are used.
- The most important area of application of zirconium is atomic power engineering. Zirconium alloys are used for manufacturing fuel elements, assemblies and structures of nuclear reactors.
- Heat-resistant compounds, alloyed with zirconium are irreplaceable in aircraft and rocket production.
- Due to its biocompatibility and durability zirconium dioxide is used in medicine as a material for surgical and dental implants.
- Cubic zirconia, synthesized on the basis of zirconium dioxide, is widely used in the jewelry industry and can serve as a substitute for diamonds and other gemstones.
