Abstract: The precursor of Mg(OH)₂ was prepared by diaphragm electrolysis with bischofite in salt lake， and then calcined to obtain nano-sized MgO， so as to realize the high-quality utilization of waste resources. The pyrolysis kinetics of the calcination process of Mg(OH)₂ was analyzed and the effects of calcination conditions on the MgO properties were investigated， combined with the pyrolysis mechanism and rate. The results show that with increasing calcination temperature， the specific surface area of MgO decreases， the activity firstly increases and then decreases， and the grain size increases. When the calcination time increases， the specific surface area and activity of MgO decreases， the grain size increases， and the structure becomes denser. Furthermore， with the increase of heating rate， the specific surface area and activity of MgO firstly increases and then becomes stable， and the grain size mainly remains unchanged. The maximum specific surface area of MgO is 29.3m²/g， the minimum CAA is 66s， and the minimum grain size is 27.8nm.

Key words: magnesium hydroxide (Mg(OH)₂); calcination; reaction kinetics; nano-sized magnesium oxide (MgO); activity