Agglomeration of gibbsite particles from carbonation process of sodium aluminate solution

The particle size distribution of the carbonation products from sodium aluminate solution was analysed based on the relative mass supersaturation and the particle number conversion from the Malvern volume distribution curves. An approximate relationship was developed which showed that the rate of change of particle number in each particle size interval (0–20 μm, 20–45 μm and 45 μm–∞) per unit volume was proportional to the rate of change of the relative mass supersaturation of the solution. The evolution of agglomeration of gibbsite particles in the carbonation process was also studied and the results show that the agglomeration rate constant is mainly influenced by the initial particle number of gibbsite Al(OH)3 under the experimental conditions. The agglomeration between fine grains (< 20 μm) plays a dominant role when the initial particle number is large, while the agglomeration between relatively coarse particles (20–45 μm) occurs with a small initial particle number. A carbonation product with extremely narrow-sized distribution and ideal large average size of 75 μm was produced by regulating the relative mass supersaturation of the solution, the amount and particle size distribution of added seeds and other carbonation parameters such as temperature and stirring rate.