1. Bioleaching/Biocorrosion Metals/Biomining
Lisa Smith
Marian Cummins
Deborah Mc Auliffe

2. Metal Contamination of soil environments and the assessment of its potential risk to terrestrial environments and human health is one of the most challenging tasks confronting scientists today.

3. Challenge for mining companies
Service-no long term impact on environment
Increasing interest in microbial approaches for recovery of base and precious metals

4. Biomining Use of microorganisms
Ores of high quality rapidly being depleted
Environmentally friendly alternative

5. Biomining Naturally existing microorganisms leach and oxidate
Bioleaching
Biooxidation

6. Bioleaching Biooxidation
Extraction of metals with the use of microorganisms
Biooxidation
Microorganisms make metal ready for extraction

7. General Properties Chemolithotrophic - “ rock eating” Autotrophic
Acidophilic ( acid loving)
Use oxygen as the preferred electron acceptor

8. Specific Microorganisms
Most common:
Thiobacillus ferrooxidans
Thiobacillus thiooxidans

9. Thiobacillus ferrooxidans
Rod shaped
Relatively quick growing
Gram negative
Strictly aerobic
Aerobic conditions uses Fe2+ or reduced S (S2-) as electron acceptor
Anoxic conditions use Fe3+ as electron acceptor
Mod. Thermophilic, temperatures of degree C and pH of 2.0

10. Thiobacillus thioxidans
Very similar to T. ferrooxidans
Can’t oxidise Fe3+

11. The Process 2 Methods- Direct and indirect
Direct- enzymatic attack and occurs at the cell membrane
Indirect- bacteria produce Fe3+ ( ferric iron) by oxidizing Fe2+ (ferrous iron)
Fe3+ is a powerful oxidizing agent that reacts with the metals and so produces Fe2+ in a continuous cycle.

12. Copper Process 25% Copper production is recovered by biomining
MS + 2O MSO4
Metal sulphide is insoluble and metal sulphate is usually water soluble
Cu ore contains CuS and CuFeS2
T. ferrooxidans brings about both direct and indirect oxidation of CuS via the generation of (Fe3+) ferric iron from (Fe2+) ferrous sulphate

13. Cu is recovered by solvent extraction or by using scrap iron where the iron replaces the Cu
CuSO4 + Fe Cu + FeSO4

14. Other Application of Biomining
Gold
Due to depletions by the 1980’s
Dependent on lower grade ore
Gold is encased in the sulphide minerals
T. ferrooxidans
Fairview mine in S. Africa
Recovery rate of 70% to 95%

15. Cont’d Phosphates industry 2nd largest agriculture chemical
5.5 million tons/ year in the US
Traditional method was burning at high temperatures (solid phosphorus) or with H2 SO4(phosphoric acid and gypsum)
Pseudomonas cepacia E37 and Erwinia herbicola
Glucose---- gluconic and 2 ketogluconic acid
Environmentally friendly as no Hs SO4 required and it occurs at room temperature.

16. Economics of Biomining
Case Studies +
Economics of Biomining

17. Microbes ‘TO TACKLE MINE WASTE’
Scientists are using microbes to clean up the problem of corrosive acid pollution left over as mining waste
Some of the microbes being used were found in America, Wales and the Caribbean island
By discovering microbes which can survive in this environment, will help address serious environmental hazards at abandoned mines and soil heaps

18. Industrial Biotechnology Biomining
Commercial Capabilities
Underpinning Existing Capabilities
Emerging Capabilities
Institutional Capabilities
Knowledge / Skills

19. Chile Biomining Program
Worlds first biggest producer of Copper
In 1971 copper mines were nationalized
But in 1990 Chile returned to democracy
Started in 1990 with tons for the year 2000
This Figure was superseded in 1995 and production exceeded 5m tons / late 1990’s

20. Economic Study of the Canadian Biotechnology
Canadian environmental & industrial biotechnology firms
Microorganisms in applications such as bioremediation leaching, energy production
Canadian Stakeholders with; U.S, European, Japanese environmental regulators

21. Biomining “There’s GOLD in them thar’ Plants!”
Gold rush miners might have been better off using plants to find gold rather than panning streams for precious metal
Early prospectors in Europe used certain weeds as indicator plants that signaled the presence of metal ore

22. Remediation Response to human health effects
Response to environmental effects
Redevelopment

23. Bioremediation
Destroys or renders harmless various contaminants using microbial activity
Bioremediation of metal-contaminated soil
Soil Flushing
Soil Washing
Phytostabilization
Phytoremediation

24. Phytostabilization Immobilization of a contaminant in soil through
Absorption & Accumulation
Adsorption
Precipitation
Also use of plant & plant root to prevent contaminant migration
Soil is then farmed to improve growth and reduce mobility and toxicity of contaminant

26. Phytoremediation Use of plants to remove contaminants from soil
Certain plant species-metal hyperaccumulators
extract metals, concentrate them in their leaves
Prevent recontamination-plants harvested

27. Leaves accumulate metals and are harvested
Roots take up metals from contaminated soil and transport to the stem, leaves

28. Biomining +Carried out insitu +Less energy input
+No toxic/noxious gases produced
+No noise or dust problems
+Process is self generating
+Large or small scale operations
+Wide variety of metals (Cu, Ag, Pb, Au, Zn)
+Work on low grade ores
-Slow process

29. Traditional extraction causes environmental problems and degradation, biomining offers an environmentally friendly alternative!!!!!!