Property Stability of Ultrafine Calcium Hydroxide Suspension Prepared by Wet Digestion: Effect of Concentration

Only the performance-stable ultrafine calcium hydroxide (Ca(OH)2) suspension has industrial practical value. This study investigated the variations in particle size, morphology, crystalline phase, sedimentation, and rheological properties of three-concentration ultrafine Ca(OH)2 suspensions (prepared via wet digestion) during 120 h of static settling. The results indicated that the three concentrations of ultrafine Ca(OH)2 suspensions exhibited consistent patterns of change in particle size, morphology, crystalline phase, sedimentation, and rheological properties during the settling process. Firstly, particle size and morphology of Ca(OH)2 only changed slightly at the initial settling stage and resumed their original states with prolonged settling. Secondly, in terms of the composition of the crystalline phase and the rheological properties, it can be observed that there is no significant change during the 120 h static settling process. Finally, regarding settling characteristics, it was found that the position of the settling interface of the ultrafine Ca(OH)2 suspension was influenced by its concentration, with the settling interface of the 18.87 wt.% suspension dropping by only 8% and that of the 9.44 wt.% suspension dropping by 48%. In conclusion, the ultrafine Ca(OH)2 suspension prepared by lime wet digestion showed excellent property stability and thus possesses considerable potential for industrial applications.