Preparation of Magnesia Nanoballs from Dolomite

Abstract

Magnesium oxide nanoballs with of 80–100 nm diameters were synthesized by chemical precipitation. The precursor magnesium hydroxide was prepared from dolomite ore as a raw material which was immersed in hydrochloric acid and then reacted with ammonium hydroxide without any surfactant. The effects of calcination temperature and time during the thermal decomposition of magnesium hydroxide precipitates on the crystal growth and morphology of the magnesium oxide particles were investigated by scanning electron microscopy and X-ray diffraction. The results show that the magnesium hydroxide layers collapsed on the (001) lattice surface and generated spherical grains of magnesium oxide with an increase in the calcination temperature. Magnesium hydroxide is completely decomposed to magnesium oxide after calcining at 400°C for 1 h. The crystallite size of the magnesium oxide increases with an increase in the temperature. The calcination time has no obvious effect on the size of the magnesium oxide grains.

Keywords:

• Dolomite
• magnesium hydroxide
• magnesium oxide
• calcination temperature
• calcination time

Acknowledgments

The authors gratefully acknowledge the support from the Fundamental Research Funds for the China Central Universities (2011PY0178).