Magnesium oxide CAS#1309-48-4
Exceptional Thermal Stability – Ultra-high melting point (2,852°C) for refractory linings and crucibles.
Versatile Industrial Additive – Enhances rubber/plastic properties and acts as a catalyst or silicon steel separator.
Flame Retardant Properties – Used in construction materials to improve fire resistance.
Medical & Agricultural Benefits – Effective antacid and soil/feed magnesium supplement.
Tailored Material Grades – Light (high surface area) and heavy (high density) forms for specialized applications.
Magnesium oxide, often referred to as magnesia or simply magnesium oxide, is a classic alkaline earth metal oxide with the chemical formula MgO. This white powdered substance has a melting point of 2852°C, boiling point of 3600°C, and relative density of 3.58 (25°C). It demonstrates solubility in acidic solutions and ammonium salt solutions, while reacting gradually with water to produce magnesium hydroxide. When introduced into a carbon dioxide aqueous solution, it forms magnesium bicarbonate. The compound tends to absorb moisture and carbon dioxide from the atmosphere over time and releases irritating fumes upon heating.
The primary sources for magnesium oxide production include magnesite (MgCO₃), dolomite (MgCO₃·CaCO₃), and seawater. The manufacturing process involves thermal decomposition of magnesite or dolomite. Alternatively, seawater treated with calcium hydroxide yields magnesium hydroxide precipitate, which is then calcined to obtain magnesium oxide. Another production method utilizes magnesium chloride brine obtained from seawater or brine after bromine extraction; adding sodium hydroxide or sodium carbonate produces magnesium hydroxide or basic magnesium carbonate precipitate, subsequently burned to yield magnesium oxide. Currently, China primarily utilizes magnesite, dolomite, brine, or brine blocks as raw materials.
Among all magnesium compounds, magnesium oxide has the highest production volume, representing approximately three-quarters of total magnesium industrial products. Magnesium oxide produced below 900°C is classified as light magnesium oxide, characterized by low density, extensive specific surface area, and notable adsorption capacity. This form serves multiple purposes: as a catalyst, rubber additive for property enhancement, and component of magnesium cement when mixed with magnesium chloride solution. It functions as a flame retardant in construction materials, an antacid and laxative in medical applications (particularly for hyperacidity and gastric/duodenal ulcers, often combined with constipating calcium carbonate), and as an additive in animal feed and plant fertilizers.
Light magnesium oxide produced between 950-1050°C exhibits greater density and specific particle size distribution, showing improved water compatibility. This variant serves as a separating agent for silicon steel plates, preventing sintering during high-temperature processing by reacting with surface silicon dioxide to form a magnesium silicate layer. Heavy magnesium oxide, produced at 1500-1800°C, features high density, minimal specific surface area, exceptional thermal stability, reduced chemical reactivity (with lower acid reactivity and hydration rate), making it suitable for high-temperature refractory applications, including manufacturing refractory crucibles and furnace linings.
