Magnesium oxide, commonly known as magnesia or magnesia oxide, is an alkaline oxide with the general properties of alkaline oxides and belongs to the category of hydraulic binders. It is a white powder (with a pale yellow tint due to magnesium nitride), odorless, and a typical alkaline earth metal oxide with the chemical formula MgO. The white powder has a melting point of 2852°C, a boiling point of 3600°C, and a relative density of 3.58 (at 25°C). It dissolves in acids and ammonium salt solutions but is insoluble in alcohol. Its solubility in water is 0.00062 g/100 mL (at 0°C).

0.0086 g/100 mL (30 °C). Exposed to air, it readily absorbs moisture and carbon dioxide, gradually becoming magnesia carbonate, with the light-weight form reacting faster than the heavy-weight. It combines with water under relative conditions to form magnesium hydroxide, exhibiting a slightly alkaline reaction; the pH of its saturated solution is 10.3. It dissolves in acids and ammonium salts but is hardly soluble in water; its solution is alkaline. It is insoluble in ethanol. It has strong refractive properties in the visible and near-ultraviolet light range. Magnesium carbonate (MgCO3), dolomite (MgCO3·CaCO3), and seawater are the main raw materials for producing magnesium oxide. Thermal decomposition of magnesite or dolomite yields magnesium oxide. Treatment of seawater with slaked lime produces magnesium hydroxide precipitate, which, upon calcination, yields magnesium oxide. Alternatively, magnesium chloride brine blocks or brine obtained after bromine extraction, from the comprehensive utilization of seawater, can also be used as raw materials. Adding sodium hydroxide or sodium carbonate results in the precipitation of magnesium hydroxide or magnesia carbonate, which, upon calcination, yields magnesium oxide. China primarily uses magnesite, dolomite, brine, or brine blocks as raw materials [1].