A new semi-dry process to produce very fine calcium carbonate powder is developed. Ca(OH)
2 slurry droplets are continuously fed into a spouted bed of coarse medium particles, and react with CO
2 in fluidizing gas to produce fine CaCO
3 powder. The CaCO
3 powder is dried with fluidizing gas, and fine CaCO
3 powder is entrained from the bed to be collected with a bag filter. The effect of operating conditions, such as the concentration of the Ca(OH)
2 slurry, CO
2 concentration in the fluidizing gas, approach to saturation temperature, superficial gas velocity and static bed height, on the conversion of Ca(OH)
2 to CaCO
3 and the particle size of product CaCO
3 powder are investigated.
Very fine CaCO
3 powder and high Ca(OH)
2 conversion are obtained in the case of low concentration of Ca(OH)
2 in the feed slurry and high concentration of CO
2 in the fluidizing gas. This method can produce very fine calcium carbonate powders with the mean particle size around 1 μm and the Ca(OH)
2 conversion around 90%.
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