Production Process of Fused Magnesia and Technical Measures

Production Process of Fused Magnesia and Its Main Technical Measures

With the rapid development of the steel industry, the requirements for the quality and performance of refractory materials have become increasingly demanding. High-performance magnesia-carbon bricks have been widely used in industrial production, and fused magnesia has developed rapidly along with advancements in magnesia-carbon brick manufacturing technology. Magnesia obtained through electric fusion features large crystal sizes, high purity, and high density, making it suitable for producing premium magnesia-carbon bricks. 

Fused magnesia offers advantages such as high purity, large crystalline grains, dense structure, strong slag resistance, and excellent thermal shock stability. Its primary crystal phase is periclase, characterized by coarse grains in direct contact. 

As such, fused magnesia is widely used in the production of high-grade magnesia bricks, magnesia-carbon bricks, and various monolithic refractories. It can also be used as a high-temperature electrical insulation material in electrical components.

Production Process of Fused Magnesia

In industrial practice, raw materials vary depending on the grade of fused magnesia being produced. Ordinary fused magnesia typically uses natural magnesite as the raw material, whereas large-crystal fused magnesia uses lightly calcined magnesia. The equipment used is a buried-electrode arc furnace, usually operating with three regenerated or non-regenerated graphite electrodes. The basic process includes: charging → igniting and raising the electrodes → gradual feeding → smelting (magnesite sinters and melts under the heat generated by high electric current) → natural cooling → crushing, grading, and manual sorting → storage. The electric fusion temperature for fused magnesia is above 2750°C.

Current Status of Fused Magnesia Production

The production of fused magnesia consumes a large amount of electrical energy. The comprehensive energy consumption per unit product is nearly 5–10 times that of similarly sintered magnesia, making it a restricted industry under China’s energy policies. At present, the overall smelting level of fused magnesia in China remains relatively low. Equipment is simple, operations are largely manual, thermal regimes and operating procedures are inadequate, and significant energy waste and environmental pollution persist. Therefore, it is urgent to upgrade the industry strategically. Conducting analytical research on the thermal processes and energy balance of fused magnesia production, and identifying effective measures for energy conservation, improving raw material utilization, and controlling dust emissions, is highly necessary.

Main Technical Measures

1. Research and development of integrated energy-saving technologies:

   • Increase electric furnace power, gradually phasing out low-power furnaces and adopting furnaces of 1600 kVA or higher, including 3500 kVA or even 5000 kVA.

   • Develop new energy-efficient furnaces with intelligent control systems to achieve optimal power usage.

   • Optimize and improve production processes and operational parameters.

2. Dust control and waste heat recovery.

3. Development and production of new types of fused synthetic aggregates.