(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:

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