A mixture of galena and silica particles has a size range 0.075-0.5 mm and is to separated by a rising stream of water at 293.2 K. Use specific gravities(Specific gravity of silica is 2.65 and galena is 7.5)

a. To obtain an uncontaminated product of galena, what velocity of water flow is needed and what is the size range of the pure product?

b. If another liquid, such as benzene, having a specific gravity of 0.85 and a viscosity of 6.50 10^-4 Pas is used, what velocity is needed and what is the size range of the pure product?