Solvent Extraction

Prepared by:Engr. Sandra Enn Bahinting

ChE 150

• Leaching (solid-liquid extraction) -involves treating a finely divided solid with a liquid that dissolves out and removes a solute contained in the solid

-The desired component, solute (A), is washed by the solvent (C) leaving the inert or insoluble solid (B) undissolved.

Two phases result:

a. overflow, V, which is a clear solution of the solute and solvent

b. underflow, L, which is the undissolved solid withsome solution adhering to it

Application of Leaching

1. biological and food processing industries a. separation of sugar from sugar beets with hot water b. the extraction of oils from peanuts, soybeans, sunflower seeds, cotton seeds, and halibut livers. c. pharmaceutical products is by leaching plant roots ,leaves and stems

2. Inorganic and organic materials a. metal processing industries

Material Balance

Example L1: Single-Stage Leaching of Flaked Soybeans In a Single-Stage

Leaching of soybean oil from flaked soybeans with hexane, 100 kg of soybeans containing 20 wt % oil is leached with 100 kg of fresh hexane solvent. The value of N for the slurry underflow is constant at 1.5 kg insoluble solid/kg solution retained. Calculate the amounts and compositions of the overflow V1 and the underflow L1 leaving the stage.

A slurry of flaked soybeans weighing total of 100kg contains 75kg of inert solids and 25kg  of solution with 10wt% oil and 90wt% solvent hexane. The slurry is contacted with 100 kg of  pure hexane in single stage so that the value of N for the outlet underflow is 1.8 insoluble solid/kg  solution retained. Calculate the amounts and compositions of the overflow V1 and underflow L1  leaving the stage.

Assignment One hundred pounds of a solid, containing 40 percent

solute (A) and 60 percent inerts (I), are treated with a solvent (S) in a single-stage contact extraction.  The extracted solids are then pressed.  The pressed solids still contain 1.2 pounds of solution per pound of solid.  Entrainment of the solids may be neglected.  Calculate the solvent of amount that is needed to perform this operation.  What would be the mass of the solute in the extract phase if 90 percent of solute in the feed is recovered?