Bioleaching

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. C haracteristics of microorganism: Requires acidic pH Capacity of deriving CO 2 and O 2 from atmosphere Requires aerobic condition. Get their carbon needed for growth from CO 2 in air.

6. Two types of leaching:

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: 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 I ndirect 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(Fe 2 ) to ferric ion (Fe 3 ) . 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.

14. THANK YOU!!!