487732840-UNIT-Proses-IN-chemical-Engineering

9
Leaching and
Extraction
Leaching is the removal of materials
from solids by dissolving them. The
chemical process industries use
leaching, but the process is usually
called extraction. Leaching of toxic
materials into groundwater is a major
health concern. Extraction processes
have the following characteristics: Two
liquid solvents must be immiscible and
have different specific gravities, and at
least one component is transferred
from one solvent to the other by a
difference in solubility. The process is
often called liquid–liquid extraction. If
one of the feed streams is a solid, the
process is called leaching or liquid–
solid extraction .In leaching, the liquid
to which materials are extracted from a
carrier is not always a solvent.