In industry, magnesium oxide is typically produced through the preliminary calcination of magnesite. Varying calcination temperatures yield magnesium oxide with distinct physicochemical properties; the products are primarily categorized as light-burned magnesia (700–1000°C), dead-burned magnesia (above 1000°C), and fused magnesia (2500–3000°C).
Light-burned magnesium oxide is mainly produced by calcining natural magnesite at temperatures between 700°C and 1000°C. Calcination temperature is the primary factor influencing the activity and purity of the product. Research by Zhao Ying, using magnesite from Dashiqiao, Liaoning, indicated that the optimal calcination conditions were a temperature of 800°C and a duration of 2 hours. Birchal et al. found that temperature was the main factor affecting the specific surface area and reaction activity of light-burned magnesium oxide. Studies by Liu Xinwei et al., using magnesite from Haicheng, Liaoning, showed optimal conditions to be a calcination temperature of 750°C, a duration of 1.5 hours, and a particle size of 1 mm. Research by Ren Weikang et al. demonstrated that the optimal heating rate was 5°C/min; calcination temperature had the greatest impact on activity, followed by raw material particle size, while the holding time had a relatively minor effect. As the calcination temperature increased, the specific surface area of the resulting magnesium oxide particles decreased, leading to lower activity; similarly, extending the holding time caused particle growth-thereby reducing specific surface area-and resulted in decreased activity. The heating rate also influences product activity: faster heating rates yield larger specific surface areas and higher MgO activity. Particle size affects the activity of light-burned magnesium oxide, though its impact is relatively minor. While ordinary and granular light-burned magnesium oxides are typically produced at 900–1000°C, these high-temperature, high-output processes suffer from significant drawbacks, namely low activity and poor gelling properties. In contrast, active light-burned magnesia is produced at 700–800°C, resulting in high dispersion, high chemical activity, and strong gelling properties.
Light-burned magnesium oxide products can also be manufactured using salt lake water as the raw material. Other preparation methods include the soda ash process, carbonation process, ammonium bicarbonate process, calcination-decomposition process, spray roasting process, and hydrothermal method. The hydrothermal method can be used to prepare nano-magnesium oxide.