Effect of the Crystal Shape of Precipitated Calcium Carbonate on the Whiteness of Modified Fly Ash

Fly ash was modified using calcium oxide and carbon dioxide. The effects of reaction temperature, the rate of carbon dioxide, and the concentration of calcium hydroxide on the crystal shape of precipitated calcium carbonate coated on the surface of fly ash were studied. The effects of the crystal shape of precipitated calcium carbonate on the whiteness of modified fly ash were analyzed. The research showed that the crystal shape of precipitated calcium carbonate was lamellar when the reaction temperature, the rate of carbon dioxide, and the concentration of calcium hydroxide were 20 °C, 0.2 L/min, 20%, respectively, which was conducive to the higher whiteness of modified fly ash.