Desulfurization of coal

1
Desulfurization of coal

• Lecture 10

2
INTRODUCTION

• During coal combustion heat is released to
  produce steam in boilers.
• Sulfur in the form of pyrite FeS2 is transformed
  into the gas phase as SOx after combustion
  process.
• One of the cheaper method of removing sulfur from
  coal is biological process.

3
Microbial desulfarization

• Bioleaching support a use of bacteria to remove
  of pyritic sulfur from coal.
• Acidithiobacillus ferrooxidans and Sulfolobus
  acidocaldarius were well known to be effective
  in removing pyritic sulfur from coal.

4
Coal structure
5
Scanining electron micrograph of A.ferrooxidans
cells attached on the pyrite surface
6
Bioflotation of pyrite and chalcopyrite
7
Pyrite bioleaching process

• 4FeS2 15O2 2 H2O 2Fe(SO4)3 2H2SO4
• This oxidation reaction releases 24.2 MJ/kgS,
  requires 1.88 kgO2/kgS and
• generate 0.76 kg H2SO4/kgS.
• Operation temperature at 35-40oC
• Operation pH in the range 1.6 1.8

8
Bioflotation and bioflocculation
9
Surfactants
10
Surface tension of surfactant solution
11
Surface tension of solution with biosurfactant
12
Surface tension of mineral suspension at the
presence of biosurfactant
13
Critical micelle concentration (cmc)
14
Micelle
15
Micelle
16
Flocculation
17
Bridging mechanism
18
Microflotation using Staphylococcus carnosus as
collector at pH9
19
Selective flocculation of Illinois 6 coal using
M. phlei
20
Adhesion of M.phlei to two coals, coal pyrite and
mineral pyrite and quartz
21
(No Transcript)
22
MEOR process

• Microbial Enhanced Oil Recovery (MEOR) is the use
  of microbes down oil wells in order to enhance
  the production of marginal oil wells. Most
  conventional oil recovery processes are only able
  to retrieve approximately 50 of the available
  oil in the area.
• The utilization of this process can extend the
  life of the average well without increasing
  excessive lifting costs.

23
MEOR process
24
Microbial Enhanced Oil Recovery
25
Microbial Enhanced Oil Recovery