Heavy magnesium carbonate also known as basic magnesium carbonate, is widely used in flour improvers,which can improve the dispersibility and fluidity of flour improvers,showing a good development prospect.The effect of reaction period of raw material concentration on product crystal was studied.

   Heavy magnesium carbonate crystals have the largest bulk density, grain nucleation and growth of crystal grain size is one of the key factors, the magnesium carbonate saturation is very big, but when the concentration of the raw material is lesser  gives off carbonate dioxide speed is bigger,also causes precipitation loose material concentration is too high or too low, will causes the product packing density lower concentration. Reaction time for the influence of temperature on packing density heavy magnesium carbonate, heavy magnesium carbonate crystals have largest bulk density of magnesium carbonate forms supersaturated state, a large number of crystal nucleus but relative solubility of magnesium carbonate precipitation will change, but the crystal growth immature grain growth immature grain grow mature gradually, basic end grain growth, liquidity is good.