The agglomeration kinetics of aluminum hydroxide in Bayer process

The effects of temperature, seed mass and agitation rate on agglomeration kinetics of aluminum hydroxide in Bayer process have been studied in a batch system. Collected raw data were analyzed and the kinetics data of agglomeration were derived through simulation of the process using a pre-developed software. The results showed that agglomeration kinetics constant (agglomeration kernel) increases with increase in temperature and agitation rate. Moreover a maximum value of agglomeration rate versus added seed mass was observed. Furthermore the magnitude of calculated activation energy of agglomeration was close to that of growth.

The experiments are carried out in different temperatures, mixing rates, and initial seed masses in a batch crystallizer. The particle size distributions (PSD) and solute concentrations have been analyzed by laser PSD analyzer and titration, respectively. The crystal size distributions and concentrations (i.e. 3rd moments) are compared with simulated results.Figure optionsDownload as PowerPoint slideHighlights
► Agglomeration kernel increases with increase of temperature and agitation rate.
► The increase of initial seed mass, results in a maximum for agglomeration kernel.
► Activation energy calculated for agglomeration is very close to that of growth.