The main crystalline phase of periclase has a melting point of 2800 ℃, which begins to sublimate in vacuum at 1600 ℃, and sublimates above 2000 ℃ in a reducing atmosphere. Its density is greater than 3.40 g/cm, porosity is 0% to 10%, Mohs hardness is 5.5, and it has strong resistance to alkaline slag erosion. Periclase is often cubic, octahedral, or irregularly granular, with complete cleavage in the cube; Linear expansion coefficient α= (14～15) × 10/℃ (0-1500 ℃) and increases as the temperature increases.
Thermal conductivity λ= 123.5W/(m · K) (at 100 ℃), which decreases as the temperature rises. The elastic modulus is 1.96 MPa. Chemical properties are stable, and there is no reaction or weak reaction with various refractory materials except silica bricks at a high temperature of 1500 ℃. The grain size of periclase increases with the increase of calcination temperature and holding time, and the corresponding slag resistance is also improved. The quality requirements for fused magnesia in China are shown in the table.
Production process
The production process of fused magnesia is short and simple, but the equipment investment and resource consumption are large. In China's fused magnesia industry, electric arc furnace melting of natural magnesite ore is often used to prepare fused magnesia. The production process and equipment are backward, with low power, small capacity, low efficiency, and low automation. The grade of fused magnesia products produced is not high, resulting in low utilization of magnesium resources and serious environmental pollution.
