Leaching

1. Minia University
Faculty of Engineering
Chemical Engineering Dept.

2. Minia University
Faculty of Engineering
Chemical Engineering Dept.

3. 1 Definition Of leaching.
2
Example Of Leaching Process.
3
Principle Of Leaching Process.
4
Uses Of Leaching

4. Is a process of mass transfer that
occurs by extracting a substance from
a solid material that has come into
contact with a liquid.
 In leaching, the liquid is very important as it
facilitates the ability to remove (or extract) a
given substance from a solid matrix (i.e.
material).

5. A simple example is the making of green tea.
Now, relate the component used in the green tea to our
definition.
1- the green tea bag is our solid mixture.
2- the green to be extracted is our desired substance.
3- and the hot water is our liquid source.

7. 1- to add hot water to a cup.
2- and now, steep the green tea bag into it.
3- not only the color changes but also the green is extracted from the
bag into the cup.
4- and after steeping some the take a sip from the cup there is not only
hot water but a delicious green tea.
Making tea is an ideal example of how leaching works.
The process goes like that:

8.  Leaching can be batch, semi batch, or continuous. It usually
operates at an elevated temperature to increase the solubility of
the solute in the solvent.
 Feed to leaching system typically is solid, consisting of basically
insoluble carrier material and a (Usually desirable) soluble
compound. The feed usually must be prepared by grinding or
chopping. It is then mixed with a liquid solvent.
The desired material dissolves (to some extent) and so leaves when
the liquid is drawn off as overflow.

9. Typical uses include:
 In the metals industry for removing mineral from ores (acid
solvents).
 Int the sugar industry for removing sugar from beets (water is
solvent).
 In the oilseeds industry for removing oil from soybeans, etc.
(hexan or similar organic solvents).