Authors:
Prof. Dr. Zongqi Guo | Liaoning Fenghua Industrial Corporation | China
Zongchun YU | Northeastern University | China
Li Wang | Dongda Dongke Drying & Calcining Technology Co., Ltd. | China
Dr. Zhaoqing Li | Dongda Dongke Drying & Calcining Technology Co., Ltd. | China
Xu Han | Dongda Dongke Drying & Calcining Technology Co., Ltd. | China
Wenjun Sun | Dongda Dongke Drying & Calcining Technology Co., Ltd. | China
High-grade natural magnesite for DBM97 production becomes seldom in China after a frenzy of mining for over 30 years. But the demand for high-purity sintered magnesia grows in high temperature industries that accompanies volatile components. Some attempts have been made at purification and densification from the flotation of low-grade natural magnesite, flash calcination in suspension calciner, and sintering in extraordinarily high temperature shaft kiln. In this work, a novel approach is developed, based on a pilot plant with the capacity of 40 t/d, to calcine natural magnesite grading as low as 40% MgO, to carry out three levels of watering treatment removing Si-, Fe- and Ca- components and hydrating MgO (gaining ˃90% Mg(OH)2), to calcine magnesia hydroxide for active MgO in suspension calciner, and finally to burn high purity magnesia to high densification. MgO hydration process is highlighted with the pivotal parameters of hydrating duration and temperature. The calcined caustic magnesia obtained has high activity of ˂20 s with citric acid. Dead burnt magnesia reaches the purity of ˃98.5% MgO and the bulk density of ˃3.4g/cm3, from low grade natural magnesite, in industrial potential.