University of TehranCollage of Engineering

School of Mine

By: Sina Ghassa

Advisor: Professor Gharabaghi

December 2013

2

Cultivation of bacteria

Bacteria Classifications

Bio-flotation Fundamentals

Bio-flotation Applications

BACTERIA CLASSIFICATION (FEEDING)

3

Autotrophic BacteriaUse atmosphere CO2 as Carbon resourceUse ammoniac as Nitrogen resource

Heterotopic BacteriaFarina, Glucose, and other nutrient have to added to cultures

Bacteria could Classified based on:

Feeding RequirementsShapeLiving Temperature

BACTERIA CLASSIFICATION (SHAPE)

4

Bacillus (A)Spirillum (B)Cocci (C)

(B)

(C)

BACTERIA CLASSIFICATION (TEMPERATURE )

5

Mesophil25-45°CAcidobacillus Ferrooxidans, Acidobacillus thiooxidans, Leptospillirum Ferrooxidans Moderate Thermophile45-65°CMost of them are heterotrophic bacteriaThermophile65-85°CSulfolobus Extremely Thermophile Upper than 85°C

CULTIVATION OF BACTERIA

6

Steps1. Enrichment Step2. Separation Step3. Purification Step

Culture Media1. Solid culture2. Liquid

CULTURE MEDIA

7

Elemental Sulfur or Ferric could be added to media as nutrient

Culture Media Compositions

CULTIVATION OF BACTERIA

8

A BACTERIA STRUCTURE

9

SURFACE CHANGES

10The surface changes of sphalerte particle in contact with bacteria (Ghassa et al. 2014)

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

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).

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)

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,

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 %.

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

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

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

19

SINA GHASSA University of TehranDecember 2013