An agitated vessel 1.8m in dia with a working depth of 2.44m is used to prepare a slurry of 150mesh Flourspar in water at 21C. The solids have a specific gravity of 3.18 and the slurry contains 25% solids by weight. The four blade pitched turbine impeller is 0.61m in dia and is located 0.5m above the vessel floor. What is the power required and the critical speed of the impeller