A continuous, counter-current leaching cascade is used to extract vegetable oil from its oil seed. The oil seed contains 20 wt% of oil, enters the process at a flow rate of 1000 kg h-1 and is leached with pure hexane which has the same flow rate. 80 wt% of oil is recovered from this process. Experimentation shows that the concentration of underflow from each stage contains 1.8 kg oil seed per kg solution. Assuming ideal leaching, determine

b) A continuous, counter-current leaching cascade is used to extract vegetable oil from its oil seed. The oil seed contains 20wt% of oil, enters the process at a flow rate of 1000kgh1 and is leached with pure hexane which has the same flow rate. 80wt% of oil is recovered from this process. Experimentation shows that the concentration of underflow from each stage contains 1.8kg oil seed per kg solution. Assuming ideal leaching, determine the: (i) Flow rate of final overflow and underflow leaving the cascade; [8 MARKS] (ii) Composition of oil in the final overflow and final underflow; [2 MARKS] (iii) Number of theoretical stages required. [5 MARKS]