Refractory Grade Magnesium Oxide 99% High Purity White Powder

Product Specification

Magnesium Oxide

Magnesium oxide (MgO), a white hygroscopic solid mineral, occurs naturally in the form of periclase and is used as a raw material for magnesium (or oxide) metallurgy. It has the empirical formula of magnesium oxide, consisting of Mg²+ ions and O2- ions bonded together to form a lattice, forming magnesium hydroxide in the presence of water (MgO + H2O → Mg(OH)2), but can be reversed to form magnesium oxide by heating to separate the water.

Magnesium oxide has historically been called white magnesia (literally meaning white minerals containing magnesium oxide - and other sources that can produce magnesium oxide, such as magnesium carbonate) to distinguish it from magnesia, a black mineral containing manganese.

While "magnesium oxide" usually refers to magnesium oxide, magnesium peroxide is also one of these compounds. Magnesium peroxide is thermodynamically stable at pressures above 116 GPa (gigaPascals), as predicted by the evolved crystal structure, and the semiconducting suboxide Mg3O2 is thermodynamically stable above 500 GPa. Due to the stability of magnesium oxide, it is used as a model system to study the vibrational properties of crystals.

Specifications

Production methods edit

Magnesium oxide is produced by calcining magnesium carbonate or magnesium hydroxide. The latter is obtained by treating a solution of magnesium chloride (usually seawater) with lime.

Mg2+ + Ca(OH)2 → Mg(OH)2 + Ca2+

Calcination at different temperatures produces magnesium oxides of varying reactivity. High temperatures of 1500-2000 °C reduce the accessible surface area and produce dead sintered (often called dead-burned) magnesium oxide, an inactive form used as a refractory. Calcination at 1000-1500 °C produces hard-burned magnesium oxide, which has limited reactivity, and calcination at lower temperatures (700-1000 °C) produces light-burned magnesium oxide, a reactive form also known as caustic-calcined magnesium oxide. Although carbonates decompose into oxides at temperatures below 700 °C, the resulting material may reabsorb carbon dioxide from the air.

Application areas

Magnesium oxide is considered a refractory material, that is, it is physically and chemically stable at high temperatures. It has two useful properties: high thermal conductivity and low electrical conductivity. To date, the refractory industry consumes most of the world's magnesium oxide. In 2004, the refractory industry consumed about 56% of magnesium oxide in the United States. The remaining 44% is used in agricultural, chemical, construction, environmental and other industrial applications.[5] Magnesium oxide is used as a basic refractory material for crucibles.

Magnesium oxide is the main fireproofing ingredient in building materials. As a building material, magnesium oxide wallboard has several excellent properties: fire resistance, termite resistance, moisture resistance, mildew resistance and high strength.

Other Uses

1. As a food additive, magnesium oxide is used as an anti-caking agent. The U.S. Food and Drug Administration has approved it for use in cocoa products, canned peas, and frozen desserts. Its E number is E530.
2. Due to its good diffusion and reflection properties, magnesium oxide is used as a reference white in colorimetry. It can be smoked to the surface of opaque materials to form a one-piece ball.
3. Magnesium oxide is widely used as an electrical insulator in tubular structure heating elements. According to the American Foundry Association, there are several mesh sizes available, with 40 and 80 mesh being the most commonly used. It is widely used due to its high dielectric strength and average thermal conductivity. Magnesium oxide is usually crushed and compacted with minimal air gaps or voids. The electrical heating industry also experimented with aluminum oxide, but it is no longer used.
4. Magnesium oxide is also used as an insulator for heat-resistant cables.
5. Magnesium oxide doping effectively inhibits grain growth in ceramics and improves the fracture toughness of ceramics by changing the crack propagation mechanism at the nanoscale.
6. Pressed magnesium oxide can be used as an optical material. It is transparent from 0.3 to 7 microns in thickness, has a refractive index of 1.72 at 1 micron and an Abbe number of 53.58. It was traded by Eastman Kodak under the now obsolete name Irtran-5. Crystalline pure magnesium oxide is commercially available and has little use in infrared optics.
7. Magnesium oxide is coated around transuranic waste at the Waste Isolation Pilot Plant to control the solubility of radionuclides.
8. Magnesium oxide has an important place as a commercial plant fertilizer and animal feed.
9. Atomized solutions of magnesium oxide are used in librarianship and collection management for deacidification of at-risk paper items. In this process, the alkalinity of magnesium oxide (and similar compounds) neutralizes the relatively high acidity of low-quality paper, thereby slowing the rate of deterioration.
10. Magnesium oxide is also used as a protective coating for plasma displays.
11. Magnesium oxide is used as an oxide barrier in spin tunneling devices. Due to its crystalline structure, thin films can be deposited by magnetron sputtering, for example, which shows superior properties to the commonly used amorphous Al2O3. In particular, MgO achieves a spin polarization of about 85%, while Al2O3 only has a spin polarization of 40–60%. The tunnel magnetoresistance values ​​of MgO (600% at room temperature and 1100% at 4.2 K) are also significantly higher than those of Al2O3 (about 70% at room temperature). MgO is thermally stable up to about 700 K, while Al2O3 is stable up to 600 K.