Loss-on-Ignition Testing of
Wood Ash
J. Leah Jones and R. W. Rice
The University of Maine
Combustion Summary
Fly Ash
Water
CO2, CH4 + +
Fuel
Char
Fixed Carbon
Total Carbon
Bottom Ash
100 (%) - M.C (%) - V.C (%) F.C (%) = Ash content (%)
• MC - Moisture content: 105 degree C for 2~3 hr using
an oven
• VC- Volatile content: 925 degree C for 7 min using a
furnace
• FC- Fixed carbon: 800 degree C for 3hr using a
furnace
Source: ASTM D3172; proximate analysis
?
LOI
• The loss-on-ignition (LOI) test is a method of
determining the mass loss from solid combustion
residues by heating (ASTM 2013).
• The mass loss can be from carbon, sulfur,
potassium, sodium and other elements found in
combustion ash.
• However, for coal and coke, it is believed that the
mass loss from the ash can be an estimate of the
amount of carbon remaining in the residue.
Equipment: LECO TGA 701
Fly and Bottom Ash
Photo: PFI Norway. http://www.pfi.no/Biorefinery/Biorefinery-Projects/Ash-Value/
Ash Sources and Types
Designator
Source
Composition
100% Sfwd
Bottom Ash, 5kW burner
100% spruce mill
residues
Mixed hrd/sfwd
Bottom Ash, 5kW burner
85% softwood mill
residue, 15% mixed
hardwood
Indust. Fly
Industrial grate burner fly
ash
Mixed biomass:
hardwood and softwood
Susp. Fly
Suspension burner
Mixed hardwood and
softwood
1200
0
1000
5
800
Mass Loss (%)
-5
Oxygen Atmosphere
10
600
15
400
20
200
Nitrogen Atmosphere
25
0
4000
8000
12000
Time (s)
Indust. Fly
Single LOI Trial of one sample
Temperature
0
16000
Temperature (C)
Temperature Profile for LOI
LOI Curves 105-1000°C
0
5
Mass Loss (%)
10
100% Sfwd
Mixed Hrd/Sfwd
Indus fly
15
Susp. Fly
20
25
0
200
400
600
Temperature (°C)
800
1000
1200
Measured LOI Values
Sample
LOI %
Std. Dev
100% Sfwd
16.87
0.44
Mixed Hrd/sfwd
26.42
0.80
Indust. Fly
21.17
2.56
Susp. Fly
21.40
1.07
Elements in Ash
Element
TC
Al
Ca
Fe
K
Mg
Mn
Na
P
S
Si
Oxide
C
Al2O3
CaO
Fe2O3
K2O
MgO
MnO
Na2O
P2O5
SO3
SiO2
Typical Composition, Mixed Species
Oxide
SiO2
CaO
K2O
Al2O3
MgO
Fe2O3
MnO
SO3
P2O5
Na2O
Vassilev et al.
31.6
28.9
13.2
6.76
5.4
5.12
2.77
2.67
2.64
1.42
Sources Vassilev et al 2010, Rice Lab
Eastern U. S.
18.67
33.1
16.34
3.63
6.78
2.68
2.34
2.65
3.52
2.05
Indust. Fly Ash Oxides
45.00
40.00
35.00
30.00
TC
Normalized %
Al
Ca
25.00
Fe
K
20.00
Mg
Mn
15.00
P
S
Si
10.00
5.00
0.00
0
100
200
300
400
500
600
Temperature °C
700
800
900
1000
Indust. Fly Ash Oxides
45.00
40.00
35.00
Normalized %
30.00
25.00
TC
20.00
Ca
Si
15.00
10.00
5.00
0.00
0
100
200
300
400
500
600
Temperature °C
700
800
900
1000
Total Carbon Percentage
14.00
13.00
12.00
Normalized Percentage
11.00
10.00
9.00
8.00
7.00
Indust. Fly
Susp. fly
6.00
Mixed hrd/sfwd
5.00
100% sfwd
4.00
3.00
2.00
1.00
0.00
0
200
400
600
Temperature °C
800
1000
100% Sfwd
0.0
9.0
8.0
4.0
7.0
6.0
6.0
8.0
5.0
4.0
10.0
3.0
12.0
2.0
14.0
1.0
16.0
200
300
400
500
600
700
Temperature (°C)
800
900
0.0
1000
Normalized TC (%)
Mass Loss (%)
2.0
Mass Loss
Normalized TC
Conclusions
• The LOI test used for coal and coke can
be adopted for use in biomass ash
• The LOI test is primarily influenced by the
carbon content of the ash
• The carbon content of the residual ash
appears to mirror the final combustion
temperature and/or the length of time of
combustion.
Thank You
The authors gratefully acknowledge USDA MacIntire Stennis project
ME 0603 and the NSF REU program for support.