Due to its unique physicochemical properties-such as a high melting point, alkalinity, and non-toxicity-magnesium oxide (MgO) is widely used across various industrial sectors. Different grades of magnesium oxide-including light-burned, heavy-burned, high-purity, and nano-scale varieties-are suited to specific applications.
Refractory Materials
Magnesium oxide serves as a raw material for producing high-grade magnesia-carbon bricks, high-calcium-magnesia bricks, and high-refractoriness powders; it is an indispensable refractory material in iron and steel smelting. In the converter slag-splashing process (used to protect the furnace lining), adding an appropriate amount of light-burned magnesia balls to the slag is an effective method for controlling the MgO content. Implementation of this technology has significantly boosted economic efficiency by extending the maximum furnace lifespan for enterprises such as TISCO, Chengde Steel, Chongqing Steel, and Maanshan Steel-increasing their service lives from 1,500, 500, 700, and 1,100 heats to 12,000, 1,500, 8,500, and 10,200 heats, respectively.
Environmental Protection
Magnesium oxide is utilized in wastewater treatment. When using magnesium oxide as a precipitant to treat wastewater with high nitrogen and phosphorus concentrations, optimal conditions-a magnesium-to-ammonia-nitrogen mass ratio of 25:1, a 10-minute reaction time, and an initial pH of 2–5-can yield removal rates of up to 93% for ammonia nitrogen and 97% for phosphorus. The resulting magnesium ammonium phosphate precipitate has potential for use as fertilizer; this method is characterized by simple operating conditions, low costs, and high removal efficiency.
Food and Animal Feed
Magnesium oxide is used as a food additive, color-fixing agent, and pH regulator, as well as in health supplements or as a food-grade magnesium source. In the animal feed sector, it supplements the magnesium required by ruminants, helping to prevent magnesium deficiency. Research indicates that adding 0.5% magnesium oxide to dairy cow concentrate supplements can increase average milk yield by 1.6 kg and milk fat content by 0.145 percentage points, while also boosting feed intake. Under heat stress conditions, increasing dietary magnesium oxide intake helps compensate for magnesium loss in the body and maintains normal milk production.
Flame-Retardant Materials
In the field of polymer materials, magnesium oxide serves as a flame-retardant synergist. In the flame-retardant modification of PA66, the synergistic use of micron-sized magnesium oxide (MgO) and aluminum diethylphosphinate significantly enhances the material's flame-retardant properties. At a total mass fraction of 10%, the composite material achieves a Limiting Oxygen Index (LOI) of 32.3%, and 1.6 mm thick samples meet the UL-94 V-0 rating. During combustion, MgO reacts with degradation products to form magnesium phosphate, promoting the creation of a dense, uniform char layer that effectively insulates against heat and oxygen.
High-end Manufacturing and Advanced Materials
Due to their excellent thermal stability, electrical insulation, optical transparency, and high thermal conductivity, high-purity and ultra-pure ultrafine magnesium oxide are widely used in high-end manufacturing sectors such as metallurgical ceramics, petrochemicals, electronics and electrical appliances, optical instruments, defense and aerospace, and food and pharmaceuticals. For instance, when used as a ceramic substrate in electronic materials, it offers twice the thermal conductivity of aluminum oxide, while its dielectric loss is merely one-tenth that of aluminum oxide.