Bioleaching is a process that uses microorganisms like Thiobacillus ferroxidans and Thiobacillus thiooxidants to extract metals from ores through leaching. These microorganisms produce acids that solubilize metal content, promoting extraction. There are two types of bioleaching - direct bioleaching where bacteria contact ores directly, and indirect bioleaching where leaching agents produced by microorganisms aid metal leaching without direct contact. Bioleaching is commonly used to extract copper from low-grade ores in an environmentally friendly way through the oxidation of ferrous ion to ferric ion by microbes, followed by chemical reactions to solubilize copper.

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.