USING ASH IN A SUSTAINABLE SOCIETY,
SWEDISH R&D PROGRAM 2002-2011
Innsbruck 22-23 mars 2010
Claes Ribbing
SVENSKA ENERGIASKOR AB
www.energiaskor.se
www.varmeforsk.se
The Vision of the
Ash Program
Combustion residues
are resources in a
sustainable society
Research program
Environmentally friendly uses of none coal ashes
1 m€/year since 2002. 40 companies and authorities
The Thermal Enginiering Research Institute of Sweden
Forestry
Environment
Geotechnigue
Land filling.
• Recycling
• Criteria's
• Roads
• Dense layers
•When outtake
of energy
• Expound laws
• Surfaces
• Stabilization
• Extra
Growth
• Test methods
• Concrete
• Quality control
• Mining
• Covering Mine
Tailings
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Results
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The results are the results from the
scientists.
The Authorities don't automatically agree
Specially not about the balance between
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The AIM of None toxic Nature
Using wastes as resources
Ash content in different fuels
The Ash Program works with all their ashes
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25% in municipal wastes
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Municipal waste contains up to 85% of bioenergi - but is
not a subject for this presentation
5% in peat (can be much more)
10-50% in sludge from paper
industry
2-4% in bark, needles and branches
0,2-0,5% in pure wood
Claes Ribbing, Svenska
EnergiAskor AB
5
Boilers
(the Pictures show rebuilt boilers at Söderenergi)
Powder cumbustion
Peat, pellets (coal)
≈ 1 200 °C
Fly ashes dominate
Grate boiler
Incinerators and
Smaller boilers less
than 100 MW
All fuels as bark, wood
chips industrial+
household Wastes etc
1 100 °C
Bottom ashes dominate
Fluidised bed.
All fuels as wood
chips, peat, wastes
≈ 850 °C
Often equal
amount fly/bottom
ashes
low NOx
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Use of ashes in Sweden 2006
Problem: Many small producers
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Roads etc
Forestry, Arable land
Backfillning to cavities
Construction on landfills
Others, unknown
Total
Production
200 kton
35 kton
50 kton (APC)
650 kton
175 kton
1 milj ton
1,3 milj ton T
Construction on landfills will more or less
disappear within 10-15 years
Ashes to forests
A Cd ion from a rottening branch is not better than the same ion from
returned ash
Outtake of bio energy
(branches and tops)
demands recycling of
ashes =(basic)
minerals to get a
sustainable forestry.
The ash must be matured
before spreading
 not to “burn” the ground
It is rather costly
Ashes and growth of forests
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In most of Sweden Nitrogen limits the rate
of growth of trees
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at rich forest soils, ashes increases the release
of in soil bound N which increases the growth
Ditched peat soils need the minerals of
ashes to get a good growth.
When the deposition of N is high,
Phosphorus is the limit for growth
P budget for different harvesting scenarios
for forests in Sweden
No harvesting
Stem harvesting
Whole-tree
harvesting
(Akselsson et al., 2008)
Conclusion
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When you take out both the stem and bio
energy in form of tops and branches you
have to return the ashes to get a
sustainable forestry
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Otherwise in the long run P and other
elements will be deficient. (not only in
Sweden?)
Nordic innovation centre
report TR 613
2008
A report most of you should intereted in
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GUIDELINE FOR CLASSIFICATION OF
ASH
FROM SOLID BIOFUELS AND PEAT
UTILISED
FOR RECYCLING AND FERTILIZING
IN FORESTRY AND AGRICULTURE
info@nordicinnovation.net
www.nordicinnovation.net
Dense layers 50/50 of fly ashes and
digested sewage sludges (dry wt)
when closure of landfills
It is dense: <10-9m/s
 It has an OK shear
strength >30kPa
 It stands settlements
 It is long lasting: the
biological and
chemical degrading
are very, very slow
(High pH, Salts, Low
perculation)
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Dense layer trails at Dragmossen
Claes Ribbing, Svenska
EnergiAskor AB
13
The Tveta method
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After a lot of research work
At the Tveta Landfill they use
wastes and specially ashes in
all layers
Layer composition for the landfill cover
system
Bio/waste ashes in concrete
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In concrete, bio fly ashes are good fillers and
can replace a lot of Portland cement
Clorides (0,1% Cl in the paste) are a problem,
they corrode the armouring-iron.
Low quality concretes are
preferred markets.
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Bio fly ashes in roads
in the sublevels
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Stiffer and stronger roads
Stabilizes bad/old materials
Less material! 1/4!
Much better frost heave
resistant
Less maintenance
No measured impact on
environment
Light weight construction
Constructions with fly ashes
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This plant for recycling of
domestic wastes – is a
light weight construction
of wood/peat fly ash on
clay soil
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Ports must be dreged
Stabilizing dredged material is
an interesting market possibility
for different fly ashes. (photo
OY Ramboll).
.
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Constructions with bottom ashes
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Grate boiler bottom ashes are good road building materials
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Even if the test results on water upptake are high
Better the more sintered the ash is.
Powder bottom ashes are often poorer due too high amount
of unburnt.
Fluid bed bottom ashes are too fine or too narrow sized to
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be good.
Test methods
Normal test methods don't suite and don't give justice to weak materials
Bottom ashes shall be tested with functional test
methods as the dynamic triaxial method
.
Modelling of Low Risk
to health and environment
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1/100 000 risk to get damaged
To get cancer (not to die of it)
 For one individual in the most exposed group
 That leads to very improbable and conservative
scenarios.
Shall not increase the the amount of undesired
impurities above normal variations in the recipient
Shall not contaminate the groundwater as to the TACmodel for landfills
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The critical scenario for low risk using Ashes as
0,5m thick sublevel in roads without other
restrictions
Dust on vegetables are more critical than leaching!
Scenario:
1/3 of his yearly intake of
Vegetables.
He hardly washes them.
Dust from
Building the road +
maintenance and demolition
20m
For gravel roads are calculated that ash is not used in the surface
layer but some ash reaches the surface through maintenance.
Moderate traffic creates dust during 64 years and 5% of the dust
is ash.
Modelling gives:
Is a low risk for using bioashes i sublevels!
Max contents
Pb
Cd
Hg
Zn
As
Free use due
to Sw EPA
No risk
20
0,2
0,1
120
10
Ashes to
forests due
to Swedish
Forests
Agency
300
30
3
7 000
30
Low local risk
gravel roads
1 400
330
80
>2,5 %
55
Low risk
leaving ashes
at the surface
exposure 40
dusty days/y
1 500
60
60
> 5%
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Uses shall be given priority when
the risk for health and
environment is low
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Modelling and tests give that most
ashes can be used as resources in a
sustainable society
Thanks for your attention
claes.ribbing@energiaskor.se
you are welcomed to mail me
This presentation will be published at
www.energiaskor.se
The synthesises of the Ash
Programme 2002-2008 (report
1111) and the database ALLASKA
are published in English at
www.varmeforsk.se
Don´t forget
TR 613 www.nordicinnovation.net