Solid-liquid mixing in agitated vessels are widely utilised in industry where there has been a demand for process intensification. It has been shown that the impeller power required per unit mass solid (epsilon-js) to achieve just off-bottom solid suspension (Njs) is dependent on solids concentration as well as tank and impeller geometry. This study aims to investigate the effect of solids concentration on epsilon-js as well as the solid-liquid mass transfer coefficient (kSL) and explore the influence of baffles and impeller configuration on these parameters. Experiments were carried out in a 0.2 m diameter, cylindrical, flat bottom agitated vessel with a liquid height of 0.3 m and equipped with two 6-bladed Rushton turbines (RT/RT) or an A310 hydrofoil and a 6-pitch bladed turbine (A310/PBT). The solid and liquid phases used were cation exchange resin and aqueous NaOH, respectively. Experimental results showed that epsilon-js decreased with increasing solid concentration (CV) up to 0.20 (v/v) in all systems studied. The results also highlighted that when baffles were removed, epsilon-js values decreased for CV range of 0.05-0.35 (v/v) and that RT/RT systems required substantially less energy to achieve Njs than systems fitted with A310/PBT. This work also indicated that kSL increased with increasing CV up to 0.20-0.25 (v/v). Also, the removal of baffles did not adversely affect kSL with A310/PBT recording slightly higher kSL than RT/RT. These results imply that removing baffles in a RT/RT mixing vessel operating at 0.20-0.25 (v/v) can intensify existing processes when all other variables are held constant.
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