Bioleaching.pptx

Bioleaching - Introduction, Microorganism used in bioleaching, Mechanism of bioleaching, Commercial processes of bioleaching, Factor affecting bioleaching, advantage & disadvantage

1. BIOLEACHING Pr esented By : Praveen Sahu M.Sc. 3 rd Semester School of Studies in Environmental Science, Pt. Ravishankar Shukla University, Raipur (C.G.) Guided by – Satendra Kumar Induria Sir

2. CONTENTS Introduction Microorganisms used in Bioleaching Mechanism of Bioleaching Commercial Process of Bioleaching Factors affecting Bioleaching Advantages & Disadvantages Conclusion References 1

3. INTRODUCTION Bioleaching is a simple and effective technology for metal extraction from low-grade ores and mineral concentrates through the use of living microorganisms. 2 Image Source - https://www.google.com/url?sa=i&url=https%3A%2F%2Fphys.org%2Fnews%2F2014-11-bioleaching-bugs-viable-method.html&psig=AOvVaw0cg3aoQFBPhVeNhsKtln3J&ust=1639240997340000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCMCv-trc2fQCFQAAAAAdAAAAABAD

4. MICROORGANISMS USED IN BIOLEACHING The most commonly used microorganisms in bioleaching are; Thiobacillus thiooxidants Thiobacillus ferrooxidants Other microorganisms which may also be used are; Bacillus licheniformis , B. luteus , B. megaterium , B. leptospirillum ferrooxidants , Pseudomonas flurescens , Sulfolobus acidocaldarius , etc 3

5. MECHANISM OF BIOLEACHING The chemical tr ansformation of metals by microorganisms may occur by direct or indirect bioleaching . DIRECT BIOLEACHING In this bioleaching, bacteria directly oxidize minerals and solubilize metals. In direct leaching, a physical contact exist between bacteria and ores and oxidation of minerals takes place through enzymatically catalyzed steps. Example : pyrite is oxidized to ferric sulphate 2FeS 2 + 7O 2 + 7H 2 O  2Fe SO 4 + 2H 2 SO 4 4

6. 2. IN DIRECT BIOLEACHING In this type of bioleaching, bacteria produces the strong oxidizing agent (MLA) such as ferric ion and sulfuric acid on oxidation of soluble iron or soluble sulfur respectively. Acidic environment maintain by oxidation of iron, sulfur, metal sulfides or by dissolution of carbonate ions. Example : bioleaching of uranium UO 2 + Fe(SO 4 ) 3 → UO 2 SO 4 + 2FeSO 4 5

7. COMMERCIAL PROCESS OF BIOLEACHING The naturally occurring mineral leaching is very slow. The microbial bioleaching process can be optimized by creating ideal conditions temperature, pH, and nutrient, O, and CO, supply etc . The desired microorganisms with nutrients acid e tc . Are pumped into the ore bed. The microorganisms grow and produce more acid. The extracted leach liquor is processed for the metal recovery. The leach liquor can be recycled again and again for further metal extraction. In commercial bioleaching, three methods are commonly used. S lope leaching H eap leaching In situ leaching 6

8. SLOPE LEACHING The ore is finally ground and dumped in large piles down a mountainside. This ore is then subjected to continuous sprinkling of water containing the desired microorganism ( T. ferrooxidans ). The liquor collected at the bottom is used for metal extraction. The water can be recycled for regeneration of bacteria. 7 Image Source - https://i2.wp.com/howbiotech.com/wp-content/uploads/2020/06/slope-bioleaching.png

9. 2. HEAP LEACHING ln this case, the ore is arranged in large heaps and subjected to treatments as in slope leaching. 8 Image Source - https://www.researchgate.net/figure/Schematic-view-of-heap-bioleaching-at-the-Escondida-mine-adapted-from-Acosta-et-al_fig1_335070287

10. 3. IN SITU LEACHING In situ leaching ore is subjected to bioleaching in it's natural occurrence. Aqueous solution of microorganisms is pumped through drilled passages within the ore. The leach liquor collected at the bottom of the ore used for the metal extraction. The permeability of rocks is increased by blasting of rock. As the acidic water seeps through the rock, it collects at the bottom which is used for metal extraction. This water can be recycled and reuse. 9

11. 10 Image Source - http://large.stanford.edu/courses/2017/ph241/hock2/images/f1big.png IN SITU LEACHING

12. FACTORS PARAMETERS Physiological Temperature , pH , Light , Pressure Oxygen and Carbondioxide Contents Microbiological Microbial Diversity Population Diversity Microbial Activity Properties of Minerals Mineral Types , Composition Grain Size , Porosity Surface Area Metal Tolerance High metal concentration may be toxic for microbes FACTOR AFFECTING BIOLEACHING 11

13. ADVANTAGES & DISADVANTAGES ADVANTAGES DISADVANTAGES Bioleaching is simpler, cheaper to operate and maintain. The bacterial leaching process is very slow. The process is more environmentally friendly than traditional extraction methods. T he heat created from the dissolving process can kill the bacteria. Ideal for low grade sulfides ores. Toxic chemicals are sometimes produced in the process. Recovery of metals from low grade ores. Low yield of minerals. No need high pressure and temperature. High risk of contaminants. 12

14. CONCLUSION Bioleaching as far as the recovery of valuable metals is concerned is not being considered today only with respect to its ability to recover valuable metals. There is a demand for less expensive and more environmentally friendly processes. Bioleaching can be considered the quickening of a characteristic ecologic process utilizing microbes that leach or discrete sulfide minerals from metal. 13

15. REFERENCES 14 U., Satyanarayana (2017). Microbial Mining and Metal Biotechnology - Bioleaching. In Biotechnology (pp. 400–403). essay, Books and Allied (P) Ltd . https://www.google.com/url?sa=i&url=https%3A%2F%2Fphys.org%2Fnews%2F2014-11-bioleaching-bugs-viable-method.html&psig=AOvVaw0cg3aoQFBPhVeNhsKtln3J&ust=1639240997340000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCMCv-trc2fQCFQAAAAAdAAAAABAD https://i2.wp.com/howbiotech.com/wp-content/uploads/2020/06/slope-bioleaching.png https://www.researchgate.net/figure/Schematic-view-of-heap-bioleaching-at-the-Escondida-mine-adapted-from-Acosta-et-al_fig1_335070287 http://large.stanford.edu/courses/2017/ph241/hock2/images/f1big.png

16. THANK YOU ANY QUERIES & SUGGESTIONS