Abstract: Light-burned magnesia as a raw material was hydrated and carbonated to obtain magnesium bicarbonate liquor. Before the pyrolyzing of magnesium bicarbonate liquor，complexants were used to cover Fe and Ca impurities.Then the treated liquid was pyrolyzed to obtain basic magnesium carbonate which was calcined to magnesium oxide with low calcium and iron content.During the complexing purification of magnesium bicarbonate liquor，the Fe and Ca removing effects of single or compound complexing agents，such as triethanolamine（TEA），citric acid，and oxalic acid were investigated.By applying triethanolamine as a complexing agent and adding 10 mL triethanolamine（1∶1） in 200 mL magnesium bicarbonate liquid， mass fractions of MgO，CaO，and Fe₂O₃ in the product were 99.3%，0.31%，and 0.042% respectively；meanwhile，using citric acid and oxalic acid as composite complexing agent，mass fractions of MgO，CaO，and Fe₂O₃ in the product were 98.2%，0.24%，and 0.030% respectively in the condition of 200 mL magnesium bicarbonate liquid with adding 1.0 g citric acid and 2.0 g oxalic acid.

Key words: magnesia, complexing purification, complexing agent, carbonization method