Abstract: Taking magnesium sulfate solution from the treatment of boric magnesium fertilizer as the raw material,basic magnesium carbonate was produced by ammonium bicarbonate method at 55~100 ℃.Products were characterized by scanning electron microscopy (SEM),X-ray diffraction (XRD),and other means,the structures and crystal morphologies of the basic magnesium carbonate prepared at different temperatures were determined.Results showed the relationship of reaction temperature and the numbers of crystal water and morphologies of basic magnesium carbonate was as follows:when at 55~60 ℃,product had about 5 crystal waters and the morphology was in the needle-like;at 65~70 ℃,6 crystal waters and morphologies are floccus and flake-like;at 75~80 ℃,8 crystal waters and morphology is cotton rod-like;at 85 ℃,6~7 crystal waters and morphology is in a transition state from cotton rod-like to spherical-like;at 90~95 ℃,4 crystal waters and morphology is spherical-like;and at 100 ℃,3 crystal waters and spherical shape was broken.

Key words: basic magnesium carbonate, crystal water, morphology, boric magnesium fertilizer