Preparation and structural characterization of high specific surface area calcium hydroxide by wet digestion of quicklime
High specific surface area calcium hydroxide can improve its reaction efficiency in the flue gas desulfurization process.Industrial quicklime was used as raw material to prepare high specific surface area calcium hydroxide by wet diges-tion.Diethylene glycol(DEG)and triethanolamine(TEA)were used as compound digestion additives(DEG/TEA),and the effects of DEG/TEA compound mass ratio,DEG/TEA compound additive amount,digestion temperature,water-to-lime ra-tio,digestion time and quicklime activity on the specific surface area and particle size of calcium hydroxide were investi-gated.Calcium hydroxide was characterized and analyzed by specific surface area analyzer,nano particle analyzer,scanning electron microscope,X-ray diffraction,and infrared spectroscopy.The findings indicated that the optimized wet digestion re-action conditions were as follows:DEG/TEA compound mass ratio of 1∶2,DEG/TEA compound additive amount of 7.5％(mass fraction),digestion temperature of 70 ℃,water-to-lime ratio of 4∶1,digestion time of 40 min.The specific surface area of the prepared calcium hydroxide was 64.44 m2/g,the total pore volume was 0.265 cm3/g,and the average particle size was 0.800 μm.Its micro-morphology was agglomerates formed by layer-by-layer stacking of nano-flakes,with well-developed slit pore structure.The research results revealed that the higher the activity of quicklime,the greater the specific surface area of calcium hydroxide produced under the same digestion conditions.Finally,the possible formation mechanism for high specific surface area calcium hydroxide was proposed.
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