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Loss-on-Ignition Testing of
Wood Ash
J. Leah Jones and R. W. Rice
The University of Maine
Combustion Summary
Fuel
Water CO2, CH4 + +
Bottom AshChar
Fixed Carbon
Total Carbon
Fly 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
Photo: PFI Norway. http://www.pfi.no/Biorefinery/Biorefinery-Projects/Ash-Value/
Fly and Bottom Ash
Ash Sources and Types
Designator Source Composition
100% Sfwd Bottom Ash, 5kW burner100% spruce mill
residues
Mixed hrd/sfwd Bottom Ash, 5kW burner
85% softwood mill
residue, 15% mixed
hardwood
Indust. FlyIndustrial grate burner fly
ash
Mixed biomass:
hardwood and softwood
Susp. Fly Suspension burnerMixed hardwood and
softwood
Temperature Profile for LOI
0
200
400
600
800
1000
1200-5
0
5
10
15
20
25
0 4000 8000 12000 16000
Te
mp
era
ture
(C
)
Ma
ss
Lo
ss
(%
)
Time (s)Indust. Fly Temperature
Nitrogen Atmosphere
Oxygen Atmosphere
Single LOI Trial of one sample
LOI Curves 105-1000°C0
5
10
15
20
25
0 200 400 600 800 1000 1200
Ma
ss
Lo
ss
(%
)
Temperature (°C)
100% Sfwd
Mixed Hrd/Sfwd
Indus fly
Susp. Fly
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 Oxide
TC C
Al Al2O3
Ca CaO
Fe Fe2O3
K K2O
Mg MgO
Mn MnO
Na Na2O
P P2O5
S SO3
Si SiO2
Typical Composition, Mixed Species
Oxide Vassilev et al. Eastern U. S.
SiO2 31.6 18.67
CaO 28.9 33.1
K2O 13.2 16.34
Al2O3 6.76 3.63
MgO 5.4 6.78
Fe2O3 5.12 2.68
MnO 2.77 2.34
SO3 2.67 2.65
P2O5 2.64 3.52
Na2O 1.42 2.05
Sources Vassilev et al 2010, Rice Lab
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
45.00
0 100 200 300 400 500 600 700 800 900 1000
No
rma
lize
d %
Temperature °C
Indust. Fly Ash Oxides
TC
Al
Ca
Fe
K
Mg
Mn
P
S
Si
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
45.00
0 100 200 300 400 500 600 700 800 900 1000
No
rma
lize
d %
Temperature °C
Indust. Fly Ash Oxides
TC
Ca
Si
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
10.00
11.00
12.00
13.00
14.00
0 200 400 600 800 1000
No
rma
lize
d P
erc
en
tag
e
Temperature °C
Total Carbon Percentage
Indust. Fly
Susp. fly
Mixed hrd/sfwd
100% sfwd
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.00.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
200 300 400 500 600 700 800 900 1000
No
rma
lize
d T
C (
%)
Ma
ss
Lo
ss
(%
)
Temperature (°C)
100% Sfwd
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.
