Question

A suspension of uniform particles in water at a concentration of 500 kg of solids per cubic meter of slurry is settling in a tank. Density of the particles is 2500 kg/m3 and terminal velocity of a single particle is 20 cm/s. What will be the settling velocity of suspension? Richardson and Zaki index is 4.6.

• A. 20 cm/s
• B. 4.3 cm/s
• C. 7.16 cm/s
• D. 3.58 cm/s

Hint:

The Richardson and Zaki index is used to calculate the settling velocity in slurries by adjusting for the effects of particle concentration.

Answer 1

The Correct Option is C

Using the Richardson and Zaki equation for the settling velocity of a slurry: \[ V_s = V_t \left( \frac{\rho_p}{\rho_f} \right)^n \] where \( V_t \) is the terminal velocity of a single particle, \( \rho_p \) is the particle density, and \( \rho_f \) is the fluid density, and \( n = 4.6 \) (Richardson and Zaki index). Substituting the values: \[ V_s = 20 \left( \frac{2500}{1000} \right)^{4.6} = 7.16 \, {cm/s} \] Conclusion: The settling velocity of the suspension is 7.16 cm/s.