3. BACTERIA CLASSIFICATION (FEEDING)
3
Autotrophic Bacteria
Use atmosphere CO2 as Carbon resource
Use ammoniac as Nitrogen resource
Heterotopic Bacteria
Farina, Glucose, and other nutrient have to
added to cultures
Bacteria could Classified based on:
Feeding Requirements
Shape
Living Temperature
5. BACTERIA CLASSIFICATION (TEMPERATURE )
5
Mesophil
25-45 C
Acidobacillus Ferrooxidans, Acidobacillus
thiooxidans, Leptospillirum Ferrooxidans
Moderate Thermophile
45-65 C
Most of them are heterotrophic bacteria
Thermophile
65-85 C
Sulfolobus
Extremely Thermophile
Upper than 85 C
11. BIO-FLOTATION
11
The Bio-Flotation have been used to reduce the using chemical
reagents to reduce the environmental impacts and
microorganisms selectivity
Bacteria could be used as:
Flotation depressants
Collectors
Dispersing agent
Flocculate
12. MECHANISMS
12
There are three different mechanisms by means of which the
biomodification can occur:
attachment of microbial cells to the solid substrate
oxidation reactions
adsorption and/or chemical reaction with the metabolite products
(EPS).
13. BACTERIA ADHESION
13
The bacterial adhesion occurs as a net result of
attractive and repulsive forces of the cell and mineral
surfaces. The interactions that result in such adhesion
include electrostatic interactions, acid–base
interactions, van der Waals forces and hydrophobic
interactions, all of which are determined by the cell-wall
and mineral surface properties (Merma et al. 2013)
14. DEPRESSANTS
14
The selective flotation separation of cinnabar from
antimonite has been carried out by Lyalikova & Lyubavina
(1986) using A. ferrooxidans. They suggested that
antimonite was oxidized by the bacteria, leading to its
depression, while cinnabar was not affected.
It was found that galena was totally depressed in the pH
range of 5-11 after bacterial interaction, while the flotation
recovery of sphalerite was not affected. The significant
differences in the adsorbabilities of the bacterial cells onto
galena and sphalerite coupled with the nature of the
interaction products, be it the respective sulfates or
hydroxides,
15. PYRITE DEPRESSANTS
15
Cyanide have been used extensively as Pyrite Depressants in
flotation processes
In the presence of A.thiobacillus Ferrooxidans, and xanthate
as collector, pyrite was depressed(40%),whereas chalcopyrite
and other sulfide minerals were unaffected at natural pH
(Hosieni et al., 2005)
The Pyrite recovery in presence of A.thiobacillus Ferrooxidans
was 8% during Galen concentrating (Mehrabani et al., 2011)
During Sphalerite concentrating the pyrite recovery is 23.52 %.
16. COLLECTOR
16
Bacillus subtilis and Mycobacterium phlei function as
collector in anionic collector flotation of dolomitic
phosphate ores, while Bacillus subtilis functions as the
stronger collector, especially for dolomite
The interaction of P. polymyxa with calcite, hematite,
corundum, kaolinite and quartz resulted in the quartz
and kaolinite surfaces being rendered more
hydrophobic
17. BIO-FLOCCULATION
17
Mycobacterium phlei was able to flocculate phosphate
slimes, hematite and coal (Smith et al., 1991)
Produce extracellular polymers and surfactants under
certain conditions, which can cause flocculation of the
microorganisms themselves or of other solids
18. REFERENCES
18
Donati, E. R., 2007. Microbial Processing of metal sulfides, Springer
Hosseini, T.R., Kolahdoozan, M.,. Tabatabaei, Y.S.M, Oliazadeh, M.,
Noaparast, M., Eslami, A., Manafi, Z., Alfantazi. A., 2005. Bioflotation of
Sarcheshmeh copper ore using Thiobacillus Ferrooxidans bacteria. Minerals
Engineering 18, 371–374
Mehrabani, J.V., Mousavi, S.M., Noaparast, M. 2011. Evaluation of the
replacement of NaCN with Acidithiobacillus ferrooxidans in the flotation of
high-pyrite, low-grade lead–zinc ore. Separation and Purification Technology
80, 202–208
Subramanian, S., Santhiya, D., Natarajan, K.A. 2003. Surface modification
studies on sulphide minerals using bioreagents. Int. J. Miner. Process. 72,
175– 188
Farahat, M., Hirajima,t., Sasaki, K., Aiba, y., Doi, K., 2008. Adsorption of SIP
E. coli onto quartz and its applications in froth flotation. Minerals Engineering
21, 389–395