it is a mass transfer operation use in chemical industries it is a simple diffusion of solid to liquid phase and foam a new concentrate liquid solution it is base on simple diffusion how to work in industries this operation it is use for pharma, seeds and oil industries.

1. LEACHING
150280105049 NIRAV RATHOD H
160283105006 PADHIYAR SHAMBHU P
160283105008 PATIL DIPAK B
160283105009 PATIL MAYUR A

2. 1. CONCEPT OF LEACHING
2. TECHNIQUE OF LEACHING
3. STEADY STATE
4. UNSTEDY STATE
In-Place (in Situ) Leaching
Heap Leaching
Shanks System (semi-batch system)
5. SINGLE STAGE LEACHING
6. MULTI STAGE LEACHING
OVERVIEW

3. Leaching is the preferential solution of one or more constituents of a solid
mixture by contact with a liquid solvent.
1. Leaching originally referred to percolation of the liquid
through a fixed bed of the solid.
2. The metallurgical industries are perhaps the largest users
of the leaching operation. For example, Copper minerals are dissolved
from certain of
their ores by leaching with sulfuric acid and gold is separated from its ores
with the aid of sodium cyanide solution.
3. Many naturally occurring products are separated from their
original structure by leaching. For example, Sugar is leached from sugar
beets with hot water, Vegetable oil are recovered from seeds such as
soybeans and cottonseed by leaching with organic solvents, and Many
Pharmaceutical products are similarly recovered from plant roots and
leaves.
CONCEPT OF LEACHING

4. 1. There are two types of method of leaching, Steady State - Continuous
mode Unsteady State
(A) Batch
(B) Semi- batch
2. Leaching operations are carried out under batch and semi-batch as well as
under completely continuous condition.
3. Two major handling techniques are used: spraying or trickling the liquid
over the solid, and immersing the solid completely in the liquid.
TECHNIQUE OF LEACHING

5. UNSTEDY STATE SYSTEM
 The Unsteady-state operations include those where
 the solids and liquids are contacted in purely batch
 wise fashion and also those where batch of solid is
 contacted with continually slowing stream of liquid
 (semi-batch method).
 1. In-Place (in Situ) Leaching
 2. Heap Leaching
 3. Shanks System (semi-batch system)

6. The Unsteady-state operations include those where the solids and
liquids are contacted in purely batch wise fashion and also those
where batch of solid is contacted with continually slowing stream
of liquid (semi-batch method).
1. In-Place (in Situ) Leaching
2. Heap Leaching
3. Shanks System (semi-batch system)
UNSTEDY STATE SYSTEM

7. MATERIAL BALANCE

8. Single Stage Leaching
 Consider a single stage leaching operation. The
 circle represents the entire operation including
 mixing of solid and leaching solvent and mechanical
 separation of the resulting insoluble phase.
 For continuous operation, weight is given in
 mass/time or mass/area*time.
 Solid B is insoluble in solvent and a clear liquid
 leach solution is obtained.
 B discharged in leached solid is same as that in
 solids to be leached.

9. Consider a single stage leaching operation. The circle
represents the entire operation including mixing of solid and
leaching solvent and mechanical separation of the resulting
insoluble phase.
For continuous operation, weight is given in
mass/time or mass/area*time.
Solid B is insoluble in solvent and a clear liquid
leach solution is obtained.
B discharged in leached solid is same as that in
solids to be leached.

10. Solute & Solvent are indicated by C & A
respectively.
B = Nf * F = E1 * N1
Solute C balance gives,
F * Yf + R0 * X0 = E1 * Y1 + R1 * X1
Solvent A balance gives,
F * (1 - Yf) + R0 * (1 - X0) = E1 * (1 - Y1) + R1 * (1 -X1)
and solution ( Solute + Solvent),
Balance gives…….(overall material balance)
F + R0 = E1 + R1 = M1

11. Multi stage Leaching

12. Assumption: The solid B is insoluble and is not lost in the liquid V phase. The
flow rate of solid is constant throughout the process.
The ideal stages are numbered in the direction of the solids or underflow
stream.
The solvent (C) – solute (A) phase or V phase is the liquid phase that
overflows continuously from stage to stage counter-currently to the solid
phase, and it dissolves solute as it moves along.
The slurry phase L composed of inert solid (B) and liquid phase of A and C is
the continuous underflow from each stage.
Composition of V – denoted by x
Composition of L – denoted by y
Multi stage Leaching

13. Multi stage Leaching

14. Mass transfer operation" by R E Treybal, Mc-Graw Hill
international, 3rd edition.
Unit Operations of Chemical Engg.ByW.L.McCabe,J.C. Smith
& Harriott, McGraw Hill international, 6th
edition .
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REFERENCES

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