Magnesium oxide

Magnesium oxide is an alkaline oxide, which has the properties of alkaline oxides and belongs to a cementitious material. White or off-white powder, odorless, tasteless, non-toxic, is a typical alkaline earth metal oxide, chemical formula MgO. The melting point is 2852°C, the boiling point is 3600°C, and the density is 3.58g/cm3 (25°C). Calcined dolomite magnesia-calcium sand is soluble in acid and ammonium salt solution, but insoluble in alcohol. Solubility in water is 0.00062 g/100 mL (0 °C), 0.0086 g/100 mL (30 °C). When exposed to the air, it is easy to absorb moisture and carbon dioxide and gradually become basic magnesium carbonate. The light product is faster than the heavy product. It combines with water to form magnesium hydroxide under certain conditions, showing a slightly alkaline reaction. The pH of the saturated aqueous solution is 10.3. Soluble in acid and ammonium salts, insoluble in water, and its solution is alkaline. Insoluble in ethanol. Strong refraction in the visible and near-ultraviolet range. Magnesite (MgCO3), dolomite (MgCO3·CaCO3) and seawater are the main raw materials for the production of magnesia. Magnesium oxide is obtained by thermal decomposition of magnesite or dolomite. The seawater is treated with slaked lime to obtain magnesium hydroxide precipitation, and magnesium hydroxide is burned to obtain magnesium oxide. The magnesium chloride brine obtained in the comprehensive utilization of seawater or the brine after bromine extraction can also be used as the raw material, and sodium hydroxide or sodium carbonate is added to generate magnesium hydroxide or basic magnesium carbonate precipitation, and then calcined to obtain magnesium oxide. China mainly uses magnesite, dolomite, brine or brine as raw materials