The document discusses the utilization of fly ash from coal power plants. It describes how fly ash can be used in cement and ceramics to add value and volume. Metals like aluminum, iron, and silica can also be extracted from fly ash. There is a need for standardized BIS specifications on using fly ash in various construction and ceramic materials to promote its utilization. The document outlines how fly ash can be incorporated in applications like bricks, tiles, concrete blocks according to different BIS codes.

1. SHRIRAM INSTITUTE FOR INDUSTRIAL RESEARCH
19, UNIVERSITY ROAD, DELHI - 110 007
Presented by :
Dr. R. K. Khandal
Director
Fly Ash: A Resource of Extraction of
Metals & High Value Products

2. Content
1. Fly Ash utilization : levels
value addition
volume addition
challenge addition
2. Utilization of Fly Ash
cement & ceramics
extraction of metals
Cenospheres
3. Need for BIS specifications
4. Path forward

3. Al2O3 TiO2
SiO2
Al
Fe
Si
U
Ti
Mg
Ca
VALUEADDITION
Ash
As such
Component
Reaction
Separation
Extraction
Fly Ash Utilization: Value addition

4. Fly Ash Utilization: Volume Addition
VOLUME ADDITION

5. As such
Wastecrete
Back filling
Land reclamation
Embankment filling
Cement concrete
Soil stabilization
Plastic composites
Bricks
Reaction
Mullite
Cenosphere
Separation
Water purification
Effluent treatment
Extraction
Al
Ca
Al2O3
TiO2
SiO2
Tiles
Glass
Ceramics
Mg
Ti
Fe
Si
U
Components
Fly Ash : Challenge addition
Each step upwards:
a)adds value and
b)involves challenges
Each step drives :
a) fly ash utilization
b) sustainable way
Challenge
Geo-polymers
Waste
Materials
Specialty
materials
Precious
Resource

6. Fly Ash: Types & Components
Other elements present in traces: Hg, Cd, Sb, Se, Ti, V (1-10 ppm)
As, Cr, La, Mo, Ni, Pb, Th, U, Zn (10-100 ppm) B, Ba, Cu, Mr, Sr(100-1000ppm)
Fly Ash
Class F Class C
1-2
Burning of Bituminous &
Anthracite
Burning of Lignite & Sub
Bituminous
1-2
Low Fe High Fe Low Ca High CaComponents
SiO2
Al2O3
MgO
K2O
TiO2
Fe2O3
CaO
Na2O
SO3
46-57
18-29
6-16
2-6
0.7-2.1
2.0-3.0
0.2-1
0.4-3
0.6-5 LOI
42-54
17-24
16-24
1-4
0.3-1
2.1-2.7
0.2-1
0.5-2
1.2-5
46-59
14-22
5-13
8-16
3-5
0.5-1
1-4
0.5-3
0.1-2
<1
25-42
15-21
5-10
17-32
4-12
0.3-1.6
1-6
0.5-5
0.1-1
<1

7. Utilization of Fly Ash : Cement

8. Cement: Composition
Al2O3
CaO
SiO2
Fe2O3
C3A C3S C2S C4AF
Lime binding modulus of fly ash = CaO / (SiO2+Al2O3+Fe2O3)

9. Portland Cement: Types (as per ASTM)
General purpose, residential purposeType I, Ia
Type II, IIa
Type III, IIIa
Type IV
Type V
 heat of hydration,  sulfate
resistance
Early high strength in one to three days
Heat during hydration kept to a minimum,
intended for large masses e.g. dams
Sulfate resistant, especially good for
marine structures & soils with high alkali
“a” type cements contain additional air entrainer

10. Portland Cement: Classification
Ingredients
I
C3S (%) 55
C2S (%) 19
C3A (%) 10
C4AF (%) 7
Others 2.8
II
51
24
6
11
2.9
ASTM Types
57
19
10
7
3
IV
28
49
4.0
12
V
38
43
4.0
9.0
1.91.8
III
45
27
11
10
7
43
50
22
11
10
53
55
17
11
9
87
33
BIS Grades
 Quality evaluation of ASTM & BIS for cement are different:
 ASTM Specifications emphasize on the oxides’ composition
 BIS specifications emphasize on the strength of cement

11. Fly Ash : Components
Component
CaO
SiO2
Al2O3
5.0
48.0
24.0
Fe2O3 10.0
Average Content(%)
Others
Range
Min (%) Max (%)
1 10
34 61
17 30
5 16
Remainder
C3S
C2S
C3A
3
2
3
C4AF 4
1
1
0
0
CaO SiO2 Al2O3 Fe2O3
0
0
1
1
0
0
0
1
45
27
11
10
Gr 33 Gr 43 Gr 53
50
22
11
10
55
17
11
9
MoleRatio
Percentage

12. Fly Ash Addition in Cement : Criteria
C3S (100%)
Grade : 33 CaO SiO2 Al2O3 Fe2O3
0 0
32.2 12.8
71.5 28.5
C3S (45%)
C2S (100%) 0 0
17.6 9.4
65.1 34.9
C2S (27%)
C3A (100%) 0 0
6.8 4.2
62.2 38.0
C3A (11%)
C4AF (100%) 0 32.9
4.6
46.1
C4AF (10%) 2.1
20.9
3.3
61.2 22.2 6.3 3.3Total

13. Composition of Cement Using Fly Ash
Component
Fly ash (100%) 5.7
1.71
55.2
16.6
CaO SiO2 Al2O3 Fe2O3
27.6
8.3
11.5
3.4Fly ash (30%)
Lime (70%) 70
Total
(Cement)
71.71 16.6 8.3 3.4
+
Answers the question as to why BIS allows Fly ash
addition in cement not more than 35%- !
5.7 55.2 27.6
8.3
11.5
3.41.71 16.6
70
71.71 16.6 8.3
5.7 55.2 27.6
8.3
11.5
3.4

14. Cement:Pozzolanic Activity
 Depends on active Silica content
 Relates to amount of active contents e.g. SiO2 & Al2O3
 Shows good strength
 Long term durability
 Corrosion resistance
 CH  Pozzolanic activity
CH + SH CSH
Pozzolanic reaction is slower than
other hydration reactions
Calcium
hydroxide
Silicic
acid
Calcium silicate
hydrate
Consumption of CH  Pozzolanic activity
SiO2 + CaO
H2O

15. Utilization of Fly Ash : Ceramics

16. Ceramic : Types
Composition
Oxides Non-oxides Composites
Al, Zr, Ce, Be •Carbides
•Borides
•Nitrides
•Fiber
reinforced,
•Particulate
reinforced

17. Ceramics Using Fly Ash
Al2O3.2SiO2.2H2O 3Al2O3.2SiO2 + 4SiO2 + 6H2O
Large amounts of CaO, Al2O3 &
SiO2
Mullite Cristobalite
∆
Kaolinite
Composition similar to glass
Typical glassy ternary system CaO-Al2O3-SiO2
Why Fly ash for Ceramics?
Significant amount of MO Act as Nucleating agents
Partial replacement for clay Clay/Fly ash blend

18. Utilization of Fly Ash : Extraction of Metals

19. Fly Ash : Extraction & Separation of Metals
Valuable components
Present at macro level (%)
Hazardous components
Present at micro level (ppm)
Fe, Al, Si Cenosphere
Valuable components
present at micro levels < 1%
Hg, Cd, Sb, Se, Ti, V (1-10 ppm)
As, Cr, La, Mo, Ni, Pb, Th, U, Zn
(10-100 ppm)
B, Ba, Cu, Mr, Sr(100-1000ppm)
Valuable components are extracted from the fly ash
using physical/chemical processes
Fly ash detoxified for hazardous components

20. Raw Material for Alumina
Type
50-70 % 17-23%
Bauxite Fly ash
Lumps Powder
Availability Geographically
distributed
Universally
abundant
Production
Al2O3 Content
Mining operation Nothing special
Fly ash can be preferred source for Al in case of countries
importing bauxite; may not be applicable in case of India
Physical
appearance

21. Separation of Alumina : Fly ash vis-a-vis Bauxite(Baeyer’s Process)
Fly ash
Removal of Carbon
Removal of Fe
Removal of Ca, Mg, N,
K, Ti, Fe(Al rich Fly ash)
Al(NO3)3 solution
3C + 4HNO3 4NO + 3CO2 + 2H2O
Heat
Magnetic separation
Treatment with weak HNO3
Treatment with conc. HNO3
Crystalization
Carbon removal prevents
addition of large vol. of HNO3
Al(NO3)3 .9H2O
Al2O3 + NO2 + H2O
Mining
Concentration
Powdered Bauxite
Removal of impurities
Al:Si ≥ 7 in raw Bauxite ore
 Fly ash contains Al:Si<7 Hence
cannot be used for this process
Lumps of Bauxite
Crushing
Al2O3 in Bauxite
+ NaOH
Al(OH)3
+ HCl + H2O
NaAlO2+ H2O + NaAl Silicate
+ Impurities(SiO2+Fe2O3+TiO2
Bauxite
Al2O3 + 3 H2O
NaCl + Red Mud
(SiO2 + Fe2O3 + TiO2)
+
Heat

22. Extraction of Iron
Hematite Ore (70% Fe2O3)
Chemical Process
Small particles of Hematite
Hematite free of clay, gangue
Fe2O3
Pig Iron(S, C, Si or P impurities)
Wrought Iron
Fly ash (5-24% Fe2O3)
Physical & Chemical Process
Residue Fly ash
C + O2 CO2
CO2 + C 2CO
Fe2O3 + 3CO 2Fe + 3CO2
CaCO3 + SiO2 CaSiO3+ CO2
Fe2O3
Breaking
Washing
Calcination
Reduction with Coke
Removal of impurities
CaCO3
Magnetic separation
Fe2O3 is
removed from fly
ash rich in Al2O3 &
Fe2O3 to use it as
refractory
material
Wrought
Iron

23. Separation of Silica From Fly Ash
Fly ash
Alkali treatment
Activated fly ash
Fly ash residue
containing Alumina
Al2O3
Separation of SiO2
from Alumina
Activation
Roasting/ acid or alkali
steeping
Clinker
Alkali addition
Solution
Al(OH)3
Carbonation
Calcination
Residue
Used as filler
or for making
cement
Sodium silicate solution
Mixture
Filteration
FiltrateResidue
Recycle
+ CaO
Carbonation
> 98% SiO2

24. Fly Ash : Extraction of Metals Present in Traces (For Detoxification)
Hg, Cd, Sb, Se, Ti, V (1-10 ppm)
B, Ba, Cu, Mn, Sr(100-1000ppm
As, Cr, La, Mo, Ni, Pb, Th, U, Zn (10-100 ppm)
Trace Metals
in Fly ash
Acid leaching
Extraction Procedures
Fly ash Fly ash free of Cu, Cd, Pb, Mn & ZnAcid
pH=3
Vaporization with Chlorine
Fly ash
Fly ash free of U impurities
Heat/C/Cl2
Volatilization of metal chlorides
Supercritical Extraction
Fly ash Fly ash free of Cu, Cd, Pb, Mn & Zn
Supercritical
CO2/Cyanex302
Phytoextraction
Soil + Fly ash Fly ash + soil with reduced
Mn, Ni, Cu, Zn& Pb)
Growth of
wetland plants
Condensation

25. Utilization of Fly Ash : Cenospheres

26. Cenospheres
Properties
• Density : 0.6 – 2 g/cm3
• Particle Size : 1-500 µ
• Spherical & hollow
Gas from coal burning Molten particles of fly ash
Spherical particles with gas entrapped
Microspheres
CENOSPHERES
Composition
•SiO2 : 65 %
•Al2O3 : 25–35%
•Fe2O3 : 1-5%
•TiO2 : 1.5%
Application
•Fillers in cement: Low
density concrete
•Foam: i) Composite
material: with metals &
Polymer ii) Automotive
sector: Aluminium foam
+

27. Cenospheres : Extraction
Extraction (Physical Process)
Wet Dry
Recovery from fly ash ponds
Disadvantages
Dissolution of toxic materials
in water
Land availability
Additional drying step
Overflow
Underflow (UF)
Main air Flow (Feed)
Sub-air
Flow
Sample
Rotor
Coarse Particles
Fine Particles
Pneumatic/micron separator

28. Utilization of Fly Ash :
Need for BIS Specifications

29. TILES
Not used at present
Specified Not yet Specified
4457
1077
9428 &
4139
6 & 8
2180
2222
2691
3583
4885
BRICKS
Fly ash lime bricks
Burnt clay fly ash bricks
894
757
Code Materials IS Code
BRICKS
Acid resistant bricks
Burnt clay bricks
Ca-silicate brick
High alumina bricks
Clay bricks
Perforated bricks
Facing bricks
Paving bricks
Sewer bricks
Materials
1237
15622
6250
1128
654
13801
TILES
Flooring tile
Ceramic tiles
Slate tiles
Limestone slab&tiles
Clay roofing tiles
Chequered tiles
Use of Fly ash : BIS Specifications

30. 15658
3006
12592
5758
CONCRETE
AAC blocks
Lime concrete
Ready Mix Concrete
Light Weight Concrete
Lime Pozzolana
Concrete Blocks
Code of Practice For
PCC & RCC
185 &
6220
541
926
142
0359
0360
56
Materials
CONCRETE
Paver block
Chemical Resistant
Paver
Manhole Cover
Precast Kerb &
Channel
12330
6907
6452
9743
CEMENT
Portland Pozzolana
Oil well Cement
Low Heat Cement
1489
8229
12600
CEMENT
Sulphate Resistant
Super sulphate
High Aluimina
Thermal Insulating
Use of Fly ash : BIS Specifications
Specified Not yet specified
Code Materials IS CodeMaterials

31. 3316
5913
10570
458
651
774
1592
14223
1197
MISCELLANEOUS
Not in use at Present
MISCELLANEOUS
Granite
Asbestos Cement
Sheets
Fire Clay
Refractory
Concrete Pipe
Stone ware pipe
Sanitary ware
Asbestos Cement
Pipe
Polished Bldg.
Stone
Mastic Asphalt
Use of Fly ash : BIS Specifications
Specified Not Yet Specified
Code Materials IS CodeMaterials

32. Utilization of Fly Ash : Path Forward

33. Utilization of Fly Ash : Path Forward
Reaction
Products
Extraction
Used as such as a
substitute for fillers
Separations of
constituents
As an additive
component to enhance
performance of the
composition
Volume Addition
C
h
a
l
l
e
n
g
e
Clockwise developmental path would be the most practical, successful &
sustainable for fly ash utilization
Key driving forces :
Realization Adoption Orientation Institutional Diffusion
Sustainability Entrepreneurial development
V
a
l
u
e
A
d
d
i
t
i
o
n

34. Thank You