From Example 4.9: Oil is to be leached from 100,000 kg/h of soybean flakes, containing 19 wt% oil, in a single equilibrium stage by 100,000 kg/h of a hexane solvent. Experimental data indicate that the oil content of the flakes will be reduced to 0.5 wt%.

I think using the below equations will give a more eloquent solution opposed to the solution manual's.

5.4. Multistage leaching of oil. In Example 4.9, 83.25% of the oil is leached by benzene using a single stage. Calculate the percent extraction of oil if: (a) two coun- tercurrent equilibrium stages are used to process 5,000 kg/h of soy- bean meal with 5,000 kg/h of benzene; (b) three countercurrent stages are used with the flows in part (a). (c) Also determine the number of countercurrent stages required to extract 98% of the oil with a solvent rate twice the minimum. E-1 EN+1 - 1 B = B S E = K'DB FA (1) B K'DB B