(i) 1000 kg of crushed oil seeds (19.5% oil, 80.5% meal) is extracted with 1500 kg of pure hexane in a batch extraction vessel. Calculate the fraction of oil extracted.

(ii) Crushed oil seed containing 28 mass% oil is to be extracted with hexane to reduce the oil content to 0.8% in the underflow. One kilogram of the solvent is used per kg of the feed. Determine the number of stages required.

The equilibrium data is given below:

 

Overflow (100 kg), solution Underflow (100 kg), slurry WA (kg) W8 (kg) Wc (kg) WA(kg) W6(kg) w(kg) 0.3 99.7 0.0 67.2 32.8 0.0 0.45 90.6 8.95 67.1 29.94 2.96 0.54 84.54 14.92 66.93 28.11 4.96 0.70 74.47 24.83 66.58 25.06 8.36 0.77 69.46 29.77 66.26 23.62 10.12 0.91 60.44 38.65 65.75 20.9 13.35 0.99 54.45 44.56 65.33 19.07 15.6 1.19 44.46 54.35 64.39 16.02 19.59 1.28 38.50 60.22 63.77 14.13 22.10 1.28 34.55 64.17 63.23 12.87 23.90 1.48 24.63 73.89 61.54 9.61 28.85