A presentation on bioleaching

1. Bioleaching
BY
C.SHANMATHI
II-YR
DEPT OF BIOTECHNOLOGY

2. Leaching:
Leaching is the process of recovery of
metals from its ores.
Leaching process which uses micro
organisms instead of chemicals is called
bioleaching.

3. Bioleaching???...
Bioleaching is the process by which metals
are dissolved from ore bearing rocks using
microorganisms.
Simplest technique to remove metals from
low grade minerals and ores.
Use microorganisms instead of chemicals
in leaching.
Non polluting to the atmosphere.

4. Microorganisms used in
bioleaching:
 Most commonly used microorganisms
 Thiobacillus ferroxidans
 Thiobacillus thiooxidants
 These micro organnisms produce some acids
which solubilizes the metal content, promoting
its extraction.

5. Characteristics of microorganism:
Requires acidic pH
Capacity of deriving CO2 and O2
from atmosphere
Requires aerobic condition.
Get their carbon needed for
growth from CO2 in air.

6. Two types of leaching:
Bioleaching
Direct
bioleaching
Indirect
bioleaching

7. Direct bioleaching:
In this process a physical contact
exists between the bacteria and the
ores , and oxidation of minerals
takes place through enzymatically
catalysed steps.

8. Indirect bioleaching:
o It’s the process in which the
microbes are not in direct contact
with minerals , but leaching
agents are produced by the
microorganisms, which helps in
leaching of metals.

9. Different process of commercial Indirect
bioleaching:

10. Copper Leaching from Low-Grade
Ores.

11.  The chemistry and microbiology of
copper ore leaching involve interesting
complementary reactions.
 The microbial contribution is the
oxidation of ferrous ion(Fe2) to ferric
ion (Fe3). Leptospirillum ferrooxidans
and related microorganisms are very
active in this oxidation.
 The ferric ion then reacts chemically to
solubilize the copper.The soluble
copper is recovered by a chemical
reaction with elemental iron, which
results in an elemental copper
precipitate.

12. Advantages :
Extraction of
metals from low
grade ores.
Environmentally
friendly process.
Disadvantages:
Very slow
process
Depend on
atmospheric
condition.

13. Why bioleaching???
To yield complete extraction of
metals.
Other process are polluting , but
bioleaching is environmentally
safe.