Why Does Zirconium Explode? How to Solve It?

Zirconium (Zr) is estimated to make up about 0.017% of the lithosphere. Because zirconium is chemically active at temperatures only slightly above normal atmospheric temperatures, it exists only in a bound state. The most common ores are zircon (ZrO2) and barium lead (ZrSiO4).

The hafnium (Hf) coexists with zirconium in all its terrestrial ores. The content of hafnium fluctuates greatly, accounting for 2% (the total amount of hafnium and zirconium). The two elements are chemically closer than any other in the periodic table, and the similarities are so great that no difference in mass has been found to separate them.

Hafnium
Hafnium

Zircon

Zircon has been considered a gem since ancient times because it is usually found in large single crystals. However, most commercial deposits of zirconium ore are in beach sand, where the relatively heavy and chemically inert zirconium minerals are retained, while the lighter parts are broken down and washed away by water. India, Malaya, Australia and the United States are known to have large deposits of this sand. Harmful substances have been found in commercially useful deposits, first in Brazil and later in other places, including Sweden, India, and Italy, while some zirconium ores are also commercially mined in Madagascar, Nigeria, Senegal, and South Africa.

Zircon is used as a component of foundry sand, abrasive, and laboratory crucible zircon and zirconia refractories. It is found in ceramic compositions and acts as an emulsifier in glazes and enamels. Zirconium and zirconia bricks are used as glass linings, zirconia templates are also used for extrusion iron and non-ferrous metal molds and injection metal nozzle linings, especially for continuous casting.

zircon-crystals
Zircon-crystals

Zirconium metal

More than 90% of zirconium is now used in nuclear power generation because zirconium has a low neutron absorption cross-section and is highly resistant to corrosion in atomic reactors, provided it contains no hafnium. In addition, zirconium is used in the manufacture of cast iron, steel, and surgical instruments, as well as in arc lamps, fireworks, special solder, plastic pigments, etc.

The powdered zirconium metal is used as a “getter” in thermionic tubes that absorb traces of residual gas after it has been drained and expelled. The metal, in the form of filaments or wool, is also used as a filter for camera flashes. Block metals can be used in the lining of reaction vessels, either pure or alloyed. It is also used as lining for pumps and piping systems in chemical processes. Excellent zirconium and niobium superconducting alloys are used in the magnetic field of 6.7T.

Zirconium-metal-strip
Zirconium-metal-strip

Zirconium compounds

Zirconium carbide and zirconium diboride are hard, refractory, metallic compounds that have been used in metal cutting tools. Diboride is also used as the shell of open-hearth thermocouple with long life. Zirconium tetrachloride is used in organic synthesis and water repellent in textiles, and it is also useful as a tanning agent.

The metal hafnium has been used as a coating for the tantalum components of rocket engines, which must work at very high temperatures and under corrosive conditions. Because of its high thermal cross-section, it is also used as control rod material in nuclear reactors. In addition, hafnium is used in the manufacture of electrodes and filament bulbs.

The harm of zirconium

It is not accurate to say that zirconium compounds are physiologically inert, but most organisms seem to tolerate zirconium quite well compared to most heavy metals. Zirconium salts have been used to treat plutonium poisoning to replace the deposition of plutonium (and yttrium) in the skeleton and to prevent precipitation when early processing begins.

Zirconium-salts
Zirconium-salts

Some studies have shown that more than 20% of zirconia can be absorbed in rats for a long time without harmful effects. LD50 of rats injected with sodium zirconium citrate is about 171mg/kg. Other investigators found an intraperitoneal injection of LD50 rats with zirconium lactate 670mg/kg, barium zirconium 420mg/kg, and mice with sodium zirconium lactate 51mg/kg.

Zirconium compounds have been recommended for topical treatment of suede dermatitis and body deodorants, among which are zirconia carbide hydrate, zirconia hydrate, and sodium zirconium lactate. There have been some reports of persistent granulomas on the skin as a result of these applications.

More immediate interest in occupational exposure is the effect of inhaled zirconium compounds, which has not been studied as extensively as other approaches to drug administration. However, there are several experiments and at least one report on human exposure. In this case, a chemical engineer who had been at a zirconium and hafnium processing plant for seven years was found to have granulomatous lung disease. As no similar damage was found on all other employees, it was concluded that the situation was most likely due to relatively high levels of beryllium prior to zirconium contact.

Animal exposure to zirconium compounds has shown that severe persistent chronic interstitial pneumonia occurs in both zirconium lactate and barium zirconium at atmospheric concentrations of about 5mg/m3. Short exposure to sodium zirconium lactate at a higher air concentration of 4900mg/m3 resulted in peribronchoabscess, peribronchogranuloma, and lobular pneumonia. Despite the lack of literature on human zirconia pneumoconiosis, the authors of one study suggest that zirconium should be considered as a possible cause of pneumoconiosis and recommend appropriate precautions in the workplace.

A small number of studies on the toxicity of hafnium compounds indicate that their acute toxicity is slightly higher than that of zirconium salts. Like soluble zirconium salts, hafnium chloride-induced cardiovascular failure and respiratory arrest in cats at 10mg/kg.

Safety and health measures

  • Zirconium is burned as a fine powder in air, nitrogen or carbon dioxide. The spontaneous air explosion of these powders at concentrations of 45,000 to 300,000 mg/m3 may be caused by static electricity generated by the separation of the disturbed particles.
Zirconium-powder-in-flame
Zirconium-powder-in-flame
  • Metal powders should be transported and treated in a wet state; water is usually used for wetting. When the powder is dried before use, the amount used should be as small as possible and should be operated in a separate compartment to prevent the spread of the explosion.
  • All ignition sources including electrostatic charges should be eliminated. All surfaces in the area should be impermeable and seamless so that they can be washed down with water and completely free from dust. Any spilled powder should be washed with water immediately so that it has no chance to dry. Old paper and cloth contaminated with powder should be kept moist in a covered container until they are removed and burned, at least daily.
  • Dry powders should be treated with as little interference as possible, and then only sparkless tools should be used. Rubber or plastic aprons, if worn on overalls, should be treated with antistatic compounds. Work clothes shall be made of non-synthetic fibers unless effectively treated with antistatic materials.
  • All processes using zirconium and hafnium should be designed and ventilated to keep air pollution below exposure limits.

Stanford Advanced Materials supplies high-quality zirconium products to meet our customers’ R&D and production needs. Please visit https://www.samaterials.com/ for more information.

What Are the Main Industrial Uses of Zircon?

Zircons are highly resistant to high temperatures and acid corrosion, and its melting can reach 2,750℃. 80% of the world’s zircons are used directly in the foundry, ceramics, glass, and refractories industries, while a small amount is used in ferroalloys, pharmaceuticals, paint, leather, abrasive, chemical, and nuclear industries. The main industrial uses of zircon are as follows.

Zircon sand

Zircon sand containing ZrO2 65~66% is directly used as casting material for the iron metal in foundry due to its melting resistance (melting point above 2500℃). Zircon sand has the lower thermal expansion, higher thermal conductivity, and stronger chemical stability than other common refractory materials, and high-quality zircon and other adhesives have a good bond and used in the foundry industry. Zircon sand is also used as bricks in glass kilns. Zircon sand and powder are mixed with other refractory materials for other purposes.

zircon-sand
Zircon-sand

Zirconium oxide

Zirconium and dolomite react together at high temperatures to produce zirconia or zirconium oxide (ZrO2). Zirconium oxide is also a good melting material, although its crystal shape varies with temperature. Stable zirconium oxide also contains small amounts of oxides of magnesium, calcium, scandium, or yttrium. The stable melting point of zirconium oxide is close to 2700℃, and it is more resistant to thermal shock than zirconium in some metallurgical applications. Stable zirconium oxide has low thermal conductivity, and the use of hafnium dioxide as fusible in industrial zirconium oxide is harmless.

Zirconium metal

Zirconium metal is mainly used in the chemical and nuclear reactor industries, as well as in other industries requiring corrosion resistance, high-temperature resistance, special fusion properties or special neutron absorption. In the United States, about 8% of the total consumption of zirconium metal is used in these industries, while the only meaningful application of the hafnium metal is in the nuclear reactors of warships.

zirconium-metal
Zirconium metal products

Zirconium metal is obtained by multistage extraction. Initially, zircon reacts with coke in an electric furnace to produce zirconium hydrocarbons and then chlorinates to produce zirconium tetrachloride. The magnesium reduction of the zirconium tetrachloride process involves the reduction of tetrachloride by placing magnesium metal in an inert gas to obtain spongy zirconium.

High purity zirconium metal can be refined by iodide thermal dissociation. In this process, metal and iodine vapors react at 200℃ and send volatile iodine to the connector, separating zirconium in the form of volatile iodine from most impurities. At about 1300℃, iodide is separated on a heated filament attached to highly purified zirconium. The released iodine is transferred from the filament, and the product is called a zirconium crystal rod.

Zirconium sponge

More than 90% of zirconium sponge is used as a zirconium-based alloy for structural and cladding materials in nuclear reactors. Zirconium is used in the chemical industry, pesticide industry, printing, and dyeing industry to manufacture corrosion-resistant reaction tower, pump, heat exchanger, valve, stirrer, nozzle, pipe, and container lining. It can also be used as a deoxidizing and denitrifying agent in the process of steelmaking and grain finisher of aluminum alloy. Zirconium wire can be used as grid support, cathode support and grid material, as well as air plasma cutting machine electrode head. Zirconium powder is mainly used as a deflagrant in the arms industry, a degassing agent in electronic devices, and it can also be used to make igniters, fireworks and flash powder.

Stanford Advanced Materials supplies high-quality zirconium products to meet our customers’ R&D and production needs. Please visit https://www.samaterials.com for more information.

The Strength of Structural Ceramics: Zirconia

In order to enable the equipment to work in a variety of harsh environments, structural ceramics, as a new material with excellent mechanical, thermal and chemical properties, have gradually replaced similar metal products and occupied an important position in modern industry. Among them, zirconia ceramics, which has excellent mechanical and thermal properties, has become a famous strength in the field of structural ceramics.

Zirconia cylinder liner and plunger

Zirconia ceramic cylinder liner and plunger have the characteristics of wear resistance, corrosion resistance, high-temperature resistance, high strength, high hardness, long service life and high impact resistance, which are widely used in oil and gas operation equipment such as mud pump, oil pump, injection pump, and fracturing pump. Compared with metal products, its product performance has been improved by 8-10 times, which greatly improves the efficiency of oil and gas exploitation, reduces the cost of exploitation, and has good economic and social benefits.

zirconia-cylinder-liner
Zirconia-Cylinder-Liner

Sander accessories

With the wide use of new energy and nano new materials, horizontal sand mill, vertical sand mill, mixing mill and other kinds of ultra-fine grinding equipment demand is rising. Because of its excellent performance, small wear and other advantages, zirconia ceramic accessories (including zirconia grinding media, turbine and left wheel, zirconia rods, grinding block, sieve, etc.) effectively improve the grinding efficiency of grinding equipment and reduce wear, so it is widely used in electrode materials, nanomaterials, ink, medicine, chemical industry, ceramics, and other industries.

Wear-resistant ceramic

Zirconia wear-resistant ceramics have the advantages of large hardness, high strength, good wear-resistant performance, long service life, heat shock and so on, and can withstand all kinds of tests in a harsh working environment, so it is often used for grinding and polishing materials, wear-resistant coating, pipe or equipment lining, equipment structure parts, and other fields. Common zirconia wear-resisting ceramic products are a wear-resisting cylinder, wear-resisting block, lining board, lining brick and liner, and so on, different product types and specifications can be selected according to different equipment and usage.

Yellow zirconia

The yellow zirconia is mainly used in various zirconia wire drawing wheel, wire drawing wheel, tower wheel. It has the characteristics of high strength, corrosion resistance, high wear resistance, good self-lubrication, good thermal stability, fatigue resistance, and high-cost performance.

zirconia-ysz-grinding-media
Zirconia-YSZ-Grinding-Media

Zirconia grinding media and ball

Zirconia grinding balls are prepared by isostatic pressure process with micron and sub-nano zirconia and yttrium oxide as raw materials. Due to the characteristics of extremely low grinding loss, high density, strong toughness, high hardness, high temperature resistance, acid and alkali resistance, corrosion resistance, magnetic resistance, etc., it is often used in the ultra-fine grinding and dispersion of materials requiring “zero pollution” and high viscosity and high hardness, which is common in electronic ceramics, magnetic materials, zirconia, medicine and food, pigments, dyes, inks, special chemical industries.

Stanford Advanced Materials supplies high-quality zirconia products to meet our customers’ R&D and production needs. Please visit https://www.samaterials.com/ for more information.