Calcination of mega-crystalline calcite using microwave and electric furnaces

Dae Ju Hwang, Jae Yong Ryu, Jung Ho Park, Young Hwan Yu, Seung Kwan Lee, Kye Hong Cho, Choon Han, Jong Dae Lee

Mega-crystalline calcite (m-CC) breaks apart easily during calcination, and is converted to CaO with difficulty due to its thermal decomposing characteristics that necessitate large heat consumption. To overcome this problem, m-CC was calcined using either a microwave furnace or an electric furnace for 15 min and 30 min at 950 °C.
Following 15 and 30 min calcinations of m-CC, almost all (96.6 wt%) and all (100%) of the calcite was calcined to CaO in the microwave furnace, compared to only 11.3 wt% and 11.0 wt% in the electric furnace, respectively. The excellent conversion rate in the microwave furnace was attributed to its internal heating method. Therefore, calcination of m-CC to CaO was optimized in the microwave furnace at 950 °C for 30 min. The results demonstrated the potential for the microwave furnace calcination of m-CC, previously known as a non-calcinable material, as a material source for CaO, Ca(OH)2 and CaCO3.

Keywords : Mega-crystalline calcite, TG/DTA, Calcinations, Microwave, Microwave furnac