Letter sent to European Commission : [email protected]
Subject : Commission Consultation on the review of the Hazardous Properties
Brussels, 29 May 2012
Dear Sir/Madam,
Members of EURELECTRIC’s Waste & Residues Working Group, together with our colleagues at
ECOBA, have been following closely developments concerning proposed revisions to the List of
Wastes (LOW, as set out in Decision 2000/532/EC) that are being considered and that are intended
to more closely align entries for hazardous wastes with definitions of hazardous appearing in other
legislation. In this respect we have noted with interest the Consultation on the Review of the
Hazardous Properties (“the consultation document”) that was recently issued by the Commission.
Having reviewed the consultation document, EURELECTRIC, ECOBA and their Members would like to
comment on the impact of what is being proposed on wastes from power stations and other
combustion plants (LOW chapter 10 01), and especially coal fly ash (LOW entry 10 01 02) which is
one of the key materials of interest to us. Whilst detailed comments are included in Annex I to this
letter, we are, in summary:

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in favour, in principle, with proposals that will simplify and harmonise the definition of
hazardous wherever it appears in products and wastes legislation;
concerned that the very detailed nature of the Technical Proposal means that industries such
as ours have had very little time to evaluate the changes in full;
extremely concerned by the prospect that coal fly ash could be classified as hazardous on the
basis of its calcium content alone, which is inappropriate; and
extremely concerned about the classification of coal fly ash as hazardous in the LOW, or even
the introduction of a hazardous mirror entry, as such a move will:
o
o
o
o
have a negative impact on the acceptability of coal fly ash for utilisation;
consequently, increase in the volumes of coal fly ash requiring disposal, at an
increased cost and at a time when void space for waste disposal, and particularly
hazardous waste disposal, is becoming increasingly scarce;
go against many years of experience, which has shown that coal fly ash does not
pose a hazard to human health and/or the environment when used beneficially or
when managed as a waste; and
be counter to the non-hazardous classification of coal ash according to both the
European Union Regulation concerning the Registration, Evaluation, Authorisation &
restriction of Chemicals (the REACH Regulations, 1907/2006) and the European
Regulation on the Classification, Labelling and Packaging of Substances and Mixtures
(the CLP Regulations, 1272/2008).
As a result of these conclusions we are strongly of the opinion that coal fly ash should not be
classified as hazardous in any regulations and certainly should remain as an absolute non-hazardous
entry on the LOW.
…/…
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.
Union of the Electricity Industry - EURELECTRIC AISBL Boulevard de l’Impératrice, 66 - bte 2
B - 1000 Brussels
Tel: + 32 2 515 10 00
Fax: + 32 2 515 10 10
VAT: BE 0462 679 112
www.eurelectric.org
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Belgium
The conclusions set out above are amplified in the more detailed comments which follow in Annex I
to this letter. Although currently being produced in lower quantities, and not addressed specifically
in this submission, we would be similarly concerned by any proposals that would classify ashes from
other combustion processes, including fly ash from peat and untreated wood (LOW entry 10 01 03),
as hazardous. As well as leading to similar consequences as those for coal fly ash, a change to the
classification of biomass ashes would almost certainly curtail the development of the biomass-fired
power stations that are already running or are being developed in a number of Member States to
deliver the EU and EC targets to reduce the carbon intensity of electricity generation.
EURELECTRIC and ECOBA are aware that a number of our Members have taken up the issues set out
in this letter with their Member State authorities. Should it be appropriate, Members of
EURELECTRIC’s Waste & Residues WG and ECOBA would be very happy to come and discuss with you
in more detail the concerns set out in this letter.
Yours faithfully,
Steve WAYGOOD
Chairman of EURELECTRIC WG Waste & Residues
Info EURELECTRIC
The Union of the Electricity Industry–EURELECTRIC is the sector association representing the common interests of the
electricity industry at pan-European level, plus its affiliates and associates on several other continents.
In line with its mission, EURELECTRIC seeks to contribute to the competitiveness of the electricity industry, to provide
effective representation for the industry in public affairs, and to promote the role of electricity both in the advancement of
society and in helping provide solutions to the challenges of sustainable development.
EURELECTRIC’s formal opinions, policy positions and reports are formulated in Working Groups, composed of experts from
the electricity industry, supervised by five Committees. This “structure of expertise” ensures that EURELECTRIC’s published
documents are based on high-quality input with up-to-date information.
For further information on EURELECTRIC activities, visit our website, which provides general information on the association
and on policy issues relevant to the electricity industry; latest news of our activities; EURELECTRIC positions and statements;
a publications catalogue listing EURELECTRIC reports; and information on our events and conferences.
Info ECOBA
ECOBA, the European coal combustion products association was founded in 1990 by European energy producers to deal with
matters related to the usage of construction raw materials from coal. The members are all generators of electricity and heat
as well as marketers. ECOBA members represent over 86 % of the CCP production in the EU 27 countries.
Annex I – Detailed Comments
Principle and Scope of the Consultation Document
EURELECTRIC, ECOBA and their Members are generally in favour of the principle to simplify and
harmonise the ways in which hazardous properties are defined in various pieces of European
legislation affecting products, by-products and wastes. However, we remain very concerned about
the possibility that a number of types of coal combustion products, and particularly coal fly ash
(entry 10 01 02 in the LOW), could be classified as hazardous wastes by either an absolute entry in
the LOW or through the introduction of a hazardous mirror entry because they contain high enough
levels of calcium (CaO and/or Ca(OH)2) for them to display Hazardous Property H8 Corrosive (as set
out in Annex III to Directive 2008/98/EC). Our strong belief is that such a classification on the basis of
concentration or calcium content alone would be inappropriate, but should rather consider their
overall exposure and environmental risks.
In reviewing the consultation document, we do recognise that the potential for the reclassification of
CaO- and Ca(OH)2-containing wastes being unjustified in all cases in view of the potential
environmental effects is acknowledged in the consultation paper’s Technical Proposal Background.
Indeed, footnote 2 of this part of the document discusses examples of potential exemptions. Whilst
the footnote confirms that the wastes of concern to us, which are particularly in chapter 10 01 of the
LOW, are “under discussion”, we are disappointed that the potential impacts of a reclassification to
the industry and to electricity consumers is not considered. As well as believing that these impacts
are significant, our disappointment is partly because the quantities of coal fly ash (38 million tonnes
of coal ash produced from coal/lignite power plants in 2008) currently produced across the European
Member States (15) are similar to the amounts of iron and steel slag that are produced (and which
are considered in the consultation document supporting report from ÖKOPOL Gmbh) and are
significantly greater than the amounts of untreated biomass ash (which are also considered in the
supporting report). In our opinion, the volumes of these ashes produced across Europe mean that
the impact of their potential reclassification should be considered in some detail before any decision
is made.
The Properties of Coal Fly Ash
Coal ashes are an inevitable consequence of the combustion of coal and lignite in large boilers used
across Europe and the world as part of the electricity generation process. Although the particle size
of coal fly ash, bottom ash, slag and boiler dust vary, each of them is essentially very similar in
chemical structure and composition; hence the reason they are typically considered together as ‘coal
ash’. The physical and chemical properties of coal ash are considered, together with information on
the beneficial uses to which they have been put over many years, in the joint EURELECTRIC/ECOBA
Briefing on the classification of coal combustion products under the revised Waste Framework
Directive (2008/98/EC) that is provided in Annex II.
The Classification of Coal fly ash under Existing Regulations
The producers of coal ashes across Europe have put in a considerable amount of effort over recent
years to evaluate the properties of their products or wastes. Under existing waste and landfill
regulations, coal ashes are classified as a non-hazardous waste and no risk or hazard to human health
and/or the environment has ever been shown.
Under REACH, the European Union Regulation concerning the Registration, Evaluation, Authorisation
& restriction of Chemicals (EC Regulation 1907/2006) registration dossiers have recently been
submitted for a number of coal combustion products (CCPs). By the 1st December 2010, separate
REACH dossiers had been submitted for a number of CCPs: ashes from wet and dry bottom boilers
(coal ash); ashes from fluidized bed combustion boilers; cenospheres; calcium sulphate; SDAProduct; and biomass ash. Each of these dossiers includes an up-to-date evaluation of the intrinsic
properties of each CCP.
Under REACH, coal ash has been registered an “Unknown or Variable composition Complex Reaction
Products or Biological Materials Substance” - a UVCB substance. The registration dossier provided
the prerequisite test data and analysis which resulted in coal ash being classified as non-hazardous in
accordance with the REACH Regulation. Based on the assessments undertaken in that report, it was
also concluded that coal ash classified as non-hazardous according to the CLP Regulations (the
Regulation on the Classification, Labelling and Packaging of Substances and Mixtures (EC Regulation
1272/2008).
So, in the opinion of EURELECTRIC, ECOBA and their Members, we contend that under existing
product and waste law coal ash is a non-hazardous product or waste when utilised or disposed of
and this evaluation should not be changed within the revision of the LOW.
Impacts of Classifying Coal Fly ash as Hazardous in the LOW
As is set out in detail in the Briefing provided in Annex II, coal fly ash has a wide range of established
uses; siliceous ashes find a wide range of uses within the construction industry, whilst calcareous
ashes are mostly used for backfilling opencast lignite mines from which the coal was taken in the first
place. EURELECTRIC, ECOBA and their Members believe strongly that the classification of coal fly ash
as hazardous in the LOW, through either an absolute or mirror entry, or in any other legislation will
have a negative impact on the acceptability of ash utilisation as perceived by both the construction
industry and the general public. The result would then be that utilisation rates for coal fly ash would
decrease significantly and, consequently, the volumes requiring disposal would increase. A decrease
in utilisation will mean that more primary aggregate will be required to replace the coal fly ash. Such
an outcome is contrary to the positive steps being taken by the Commission and many Member
States to encourage the use of by-products and recovered wastes over primary aggregate, and as set
out in the Roadmap to a Resource Efficient Europe launched by the Commission in September 2011.
In addition, the significant benefits of reducing CO2 emissions by replacing cement with coal fly ash in
construction and construction products will be lost. An increase in the volume of coal fly ash
requiring disposal will also have significant ramifications across Europe, where void space for waste
disposal, and particularly hazardous waste disposal, is becoming increasingly scarce. Hazardous
waste landfill sites have to be engineered to a higher standard than is necessary for the disposal of
coal fly ash. In addition, in many Member States landfilling of hazardous wastes attracts a
significantly higher rate of Landfill Tax, which would further increase disposal costs.
The introduction of a mirror hazardous entry for coal fly ash in the LOW will also have other
significant implications. Primarily it will lead to uncertainty as to whether any particular batch of coal
fly ash is a hazardous waste or not - coal fly ash varies in composition in the same way that the
composition of the parent coal from which it is derived, and which is a natural product, varies. As a
result, significantly more testing will have to be done to determine whether a particular batch of coal
fly ash is hazardous or not, and therefore which LOW entry is applicable, than is currently accepted
by both the industry and the regulatory authorities as necessary.
We have not been aware of any specific proposals before this one to change the classification of coal
fly ash on the LOW since the list was published in 2000 as Decision 2000/532/EC. Were the
Commission’s proposal to classify coal fly ash as a hazardous waste, either definitively or via a
hazardous mirror entry in the LOW, to be subject to a full financial impact assessment, then we
strongly believe that the results would show a significant negative impact over the current position
and one which is not justified on the grounds of environmental or exposure impact.
Comments on the Technical Proposal
In reviewing the consultation document, we are very aware that the content of the Technical
Proposal is very detailed. In this respect, we feel that industries such as ours have had very little time
to evaluate the proposed changes in full. In our opinion, the impacts of the proposed changes cannot
be evaluated in such a short timeframe and therefore we would appreciate it if more time would be
granted for us to work with yourselves to understand the full implications of the proposals and to
determine the correct approach for coal fly ashes. In the meantime, to avoid a presumptive change
which would make all coal fly ashes hazardous, and so no longer be so attractive for beneficial use,
we strongly recommend that the existing classification system is used until further work is
completed. In our opinion such an approach would be consistent with the comments in the
Background to the Technical Proposal of the consultation document which states both that “Given
that reliable and detailed information about wastes (e.g. statistics about the types and amounts of
wastes classified as hazardous by a given hazardous property) is not available at EU level, the impacts
of the changes cannot be established in all cases with certainty” and that “There may be some cases
where changes in chemicals classification could lead to changes in waste classification that would not
be justified in all cases in view of the potential environmental effects.”
Conclusion
In conclusion, EURELECTRIC, ECOBA and their Members strongly believe that the reclassification of
coal fly ash as a hazardous in any regulations on the basis of its calcium content alone is entirely
inappropriate. The impact of doing so would be to significantly reduce utilisation of the material,
consequently increasing the amounts requiring disposal at landfill sites engineered to an
unnecessarily high standard and attracting a higher taxation rate. The costs of such disposal would
increase significantly over those currently experienced and would therefore add significantly to the
cost of coal-fired electricity generation across Europe, potentially making it uneconomic and/or
increasing process to the consumer. In our view, such a move could therefore run the risk of security
of supply issues.
The introduction of an absolute hazardous entry for coal fly ash in the LOW, or even a hazardous
mirror entry, would be inconsistent with its classification under the REACH and CLP Regulations and
would have significant implications; above all, it would produce a negative perception of coal fly ash,
which would have the same impact as an absolute hazardous classification. Coal fly ash has been
shown over many years not to pose a hazard to human health and/or the environment when
managed as a waste and so should remain as an absolute non-hazardous entry on the LOW.
Annex II - EURELECTRIC/ECOBA position paper on the Classification of Coal
Combustion Products under the revised Waste Framework Directive
(2008/98/EC) (Final 08/11/10)
European Coal Combustion Products Association
Joint EURELECTRIC/ECOBA Briefing:
The Classification of Coal Combustion Products under the
revised Waste Framework Directive (2008/98/EC)
Each year, more than 100 million tonnes of coal and lignite ashes and desulphurisation
products are produced by power stations throughout the European Union in addition to the
main product electricity. These solid materials, which can be described collectively as coal
combustion products1 (CCPs [1]), are inevitable as they are produced as a result of
requirements to meet air emission standards set in other EC Directives [2]. Each of the CCPs
has specific physical and chemical properties that make them suitable for utilisation in
established markets which have, typically, existed for many years. These applications include,
amongst others, use in cement, as both raw kiln feed material and as a direct cement
replacement [3], in concrete [4], in the production of lightweight aggregates and lightweight
blocks [5], as aggregates in building and road industries [6], in mining and other operations as
a construction or fill material [7], as mineral fillers [8] and, in the case of FGD gypsum, as a
raw material in the gypsum industry for the production of plasterboard and as a set retarder in
the cement industry [9]. Further details of the production, properties and use of various CCPs
are described in an accompanying document [Annex 1].
In many applications CCPs are used as a replacement for naturally occurring materials and
therefore offer environmental benefits by avoiding the need to quarry or mine primary
resources. The use of CCPs is thus an excellent example of sustainability, results in the
saving of natural resources and material and, in many cases, helps to reduce energy demand
and emissions to the atmosphere which result from the extraction or manufacture of the
substituted product [10]. A significant example of the positive environmental benefits that come
from the use of CCPs is the use of coal fly ash in concrete and blended cement, where, as
well as savings in natural resources and energy, the use of every tonne of ash saves about
one tonne of CO2 when compared to the use of cement itself [11]. Numerous studies (toxicity,
lab and on-site evaluations etc.) have shown that CCPs have no negative impact on the
environment or on human health when put to beneficial use. Also, to be effectively used in a
number of applications, they have to satisfy relevant national and European building materials
standards and regulations or user-imposed technical requirements. Not only do these
standards set quality criteria for utilisation, but their existence in itself is a recognition that the
materials are of value.
Where CCPs are used directly from the power station or after short periods of storage in
dedicated silos, stores and stockpiles designed to maintain them in a form suitable for use,
they are, in the producer’s opinion, not discarded and are not ‘wastes’ as defined in the Waste
1
The term “coal combustion products” (CCPs) is commonly used for ashes and desulphurisation
products produced following the combustion of coal for power and steam generation. It is synonymous
with terms such as “coal combustion residue”, “secondary mineral”, “secondary raw material” and
“secondary product“ used in other publications and regulations.
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Framework Directive (2008/98/EC) [12]. The use of CCPs in these ways is consistent with the
aims of the Directive and, in particular, with the waste hierarchy set out in Article 4, which puts
waste prevention above options such as re-use, recycling and recovery [13]. In each case
where they are utilised, their further use is certain, they are suitable for use in their existing
form and without undergoing any further processing other than normal industrial practice and
their use meets all of the relevant product, environmental and health standards applicable to
that use. Therefore, CCPs going directly from the power station that produced them or from an
associated production process to an end-user in a form which is suitable for immediate use
are excellent examples of by-products as defined in Article 5 of the Directive [14]. As byproducts will be substances that will be placed directly on the market, they will be subject to
the REACH regulation [15]. As such CCPs should be included within any guidance to
accompany the revised Directive as examples of industrial by-products which should never be
considered as wastes. As the REACH registration contains a full description of the chemical,
mineralogical, physical, toxicological and ecotoxicological characterisation of CCPs, as well as
a chemical safety report and an assessment report with exposure scenarios reflecting the use
of the materials, there is no need for additional parameters to verify the by-product status.
In circumstances where CCP production levels exceed demand or where demand varies
temporally, some of them, and fly ash in particular, are discarded as wastes and are typically
landfilled at mono-disposal sites. However, should demand subsequently increase it is very
easy for the materials to be recovered and, with only minimal treatment, they can then be used
in the same markets as ‘fresh’ materials. In these cases, the materials have ceased to be
wastes at the place of recovery in line with the end-of-waste criteria set out in Article 6 of the
Directive [16]. As such, recovered CCPs are an excellent example that could be used in any
guidance to accompany the Directive as a waste stream which, when recovered, ceases to be
waste.
In summary, the production of CCPs is an inevitable consequence of the combustion of coal in
large power plant boilers. Although not the main commercial product of the process, CCPs are
of value in a number of other ways and, as shown in Figure 1, are used either immediately or,
in the longer-term, after recovery from stockpile or mono-landfill sites. In the former case,
CCPs should be regarded as by-products and never as wastes; in the latter case, once
recovered, CCPs should cease to be wastes and become products at the place of recovery
(Figure 1).
EURELECTRIC and ECOBA believe that, in both cases, CCPs are very good examples for
use in any guidance produced to accompany the revised Waste Framework Directive
(2008/98/EC).
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Fig. 1: Flow chart describing definitions
PROCESS
Resulting from the
primary operation
Primary operation
COAL COMBUSTION
PRODUCTS
MAIN PRODUCT
(electricity, steam and
heat)
(coal and lignite ashes and
desulphurisation products)
Directly useable
Not directly useable
WASTE
BY-PRODUCT
(utilisation as a PRODUCT
covered by product
regulations and REACH)
(covered by the revised Waste
Framework and other
Directives)
Recovery
END-OF-WASTE
(utilisation as a PRODUCT,
covered by product regulations
and REACH)
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[1]
For the purposes of this Note, coal combustion products (CCPs) are: bottom ash, boiler
slag and fluidised bed combustion (FBC) ash (i.e. bottom ash, slag and boiler dust
according to EWC Codes 10 01 01 and 10 04 15); coal fly ash (10 01 02 and 10 01 17);
and calcium-based reaction wastes from flue-gas desulphurisation in solid form (10 01
05).
[2]
As the descriptor suggests, bottom ash, slag and boiler dust are retained within the
boiler following combustion and are removed in a number of ways depending on the
furnace design. Fly ash, on the other hand, leaves the boiler entrained in the flue gases
and, in order to meet air quality requirements set out in EC Directives, like the Large
Combustion Plant Directive (2001/80/EC), is typically removed prior to the power station
stack by electrostatic precipitation.
Flue gas desulphurisation products result from the treatment of the flue gases prior to
emission to reduce the sulphur content of the exhaust gases. A number of techniques
are commercially available to do this and the exact nature of the product depends on the
technique employed.
An accompanying document [Annex 1] describes, in more detail, production routes and
properties of various CCPs.
[3]
Fly ash and bottom ash can be used in the manufacture of cement in two ways; as a raw
material for cement clinker production or as a major constituent in the production of
blended cement. In the former case ash serves as a source of silica and alumina, which
traditionally come from natural sand and clay.
For the production of blended cement, i.e. Portland pozzolana and Portland fly-ash
cement typically containing around 30% fly ash, ash has to meet the requirements of
European standard EN197-1 which includes a requirement for conformity evaluation.
[4]
Fly ash is added to concrete to enhance its technical performance for a number of
reasons. The physical and chemicals properties of the ash that can be used in this
application, together with details of the conformity evaluation, are detailed in European
Standard EN 450, Fly ash for concrete – definitions, specifications and conformity
criteria.
[5]
Fly ash is used as a siliceous source in the manufacture of aerated concrete blocks.
These have excellent insulating properties for a cementitious material and consist of
~85% fly ash. Ash used in these applications has, again, to meet the requirements of
European Standards.
Fly ash has also been used as the raw material in the manufacture of lightweight
aggregates according to European Standard EN 13055. Bottom ash is also used as a
coarse and fine aggregate in the manufacture of ‘Lightweight Concrete Blocks’. For this
application, it has to meet the requirements of the European Standard for lightweight
aggregates, EN 13055. Bottom ash is the preferred material by all manufacturers due to
the lightweight nature and stability of the aggregate.
[6]
Fly ash, bottom ash and boiler slag are used in a number of applications as aggregates
in building and road construction. Specific examples include the use of bottom ash as a
drainage layer and road sub-base material and as a wearing surface in equestrian
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centres and car parks. In these applications, the requirements of European and national
standards typically have to be met.
[7]
Fly ash has been widely used as a fill material for a number of years. In this application,
and in road construction in particular, its use has been based on its availability, its ease
of compaction and its ability to form stable, durable landforms. Examples include its use
in embankments and bridge abutments. In addition, for use in underground mining,
reactivity requirements have to be met.
[8]
Fly ash, as well as cenospheres, i.e. hollow sphere fly ash particles with ultra-low
densities, are used as a fill material in a number of applications, including paints,
plastics, car body panels, glass fibre resin systems and refractory panels.
[9]
Most of the FGD gypsum produced in Europe is utilized in the gypsum and cement
industries in products like plasterboard, gypsum blocks and plasters. The quality criteria
for the use of FGD gypsum as a raw material for the gypsum and cement industry are
defined in a number of standards.
[10]
In many of the applications developed for CCPs, their utilisation results in economic
benefit. Most applications, however, also provide environmental benefits, including:
–
–
–
–
–
saving of natural resources;
saving of energy;
saving of emissions of pollutants to the air;
saving of CO2 emissions;
saving of landfill space.
At least one, and in most cases several, of the environmental benefits apply to all
applications of fly ash.
[11]
Following on from [10], the most impressive example is the replacement of a part of
cement by fly ash in concrete or the use of fly ash as a main constituent of blended
cement. For the production of one tonne of cement about 1.6 tonnes of raw material
have to be mined, crushed, calcined and heated to a temperature of 1200 to 1400°C. In
addition, 0.95 tonnes of material have to be finely ground to produce Portland cement.
2900 MJ of thermal energy and 100 kWh of electrical energy are needed to produce one
tonne of Portland cement.
The production of Portland cement is not possible without emissions of pollutants to air
even though the emissions from cement production have been drastically reduced in the
last few decades. The production of Portland cement is also inevitably associated with
CO2 emissions due to the calcination process and the energy demand. The replacement
of Portland cement by fly ash therefore makes a corresponding reduction in the various
environmental impacts associated with cement production. In the EU15 member states it
is conservatively estimated that the use of 2.9 million tonnes of fly ash in cement
manufacture results in a reduction in CO2 emissions of the same amount per annum.
Many of the other uses of CCPs do at the very least avoid the environmental impact of
the mining of natural resources and the processing of the minerals and save the space
needed for the disposal of CCPs.
[12]
According to Article 3 of Directive 2008/98/EC on waste, ‘waste’ means ‘any substance
or object which the holder discards or intends or is required to discard’.
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[13]
Article 4 of Directive 2008/98/EC describes the waste hierarchy and is reproduced below
for reference.
Article 4
Waste hierarchy
1. The following waste hierarchy shall apply as a priority order in waste prevention and
management legislation and policy:
(a) prevention;
(b) preparing for re-use;
(c) recycling;
(d) other recovery, e.g. energy recovery; and
(e) disposal.
2. When applying the waste hierarchy referred to in paragraph 1, Member States shall
take measures to encourage the options that deliver the best overall environmental
outcome. This may require specific waste streams departing from the hierarchy where
this is justified by life-cycle thinking on the overall impacts of the generation and
management of such waste.
Member States shall ensure that the development of waste legislation and policy is a
fully transparent process, observing existing national rules about the consultation and
involvement of citizens and stakeholders.
Member States shall take into account the general environmental protection principles of
precaution and sustainability, technical feasibility and economic viability, protection of
resources as well as the overall environmental, human health, economic and social
impacts, in accordance with Articles 1 and 13.
[14]
Article 5 of Directive 2008/98/EC deals with by-products and is reproduced below for
reference.
Article 5
By-products
1. A substance or object, resulting from a production process, the primary aim of which
is not the production of that item, may be regarded as not being waste referred to in
point (1) of Article 3 but as being a by-product only if the following conditions are met:
(a) further use of the substance or object is certain;
(b) the substance or object can be used directly without any further processing
other than normal industrial practice;
(c) the substance or object is produced as an integral part of a production
process; and
(d) further use is lawful, i.e. the substance or object fulfils all relevant product,
environmental and health protection requirements for the specific use and will not
lead to overall adverse environmental or human health impacts.
2. On the basis of the conditions laid down in paragraph 1, measures may be adopted to
determine the criteria to be met for specific substances or objects to be regarded as a
by-product and not as waste referred to in point (1) of Article 3. Those measures,
designed to amend non-essential elements of this Directive by supplementing it, shall be
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adopted in accordance with the regulatory procedure with scrutiny referred to in article
39(2).
[15]
REACH is the European Community Regulation on chemicals and their safe use (EC
1907/2006) which entered force on 1st June 2007. It deals with the Registration,
Evaluation, Authorisation and Restriction of Chemical substances. The aim of REACH is
to improve the protection of human health and the environment through the better and
earlier identification of the intrinsic properties of chemical substances.
Under the REACH Regulation, producers, manufacturers and importers are required to
gather information on the properties of their chemical substances and to register the
information in a central database run by the European Chemicals Agency (ECHA) in
Helsinki.
The producers of CCPs have registered their products for use in the construction
industry under REACH. All information about the chemical, physical, toxicological and
ecotoxicological properties were compiled in a registration document which will be
published at the ECHA.
[16]
Article 6 of Directive 2008/98/EC deals with end-of-waste and is reproduced below for
reference.
Article 6
End-of-waste status
1. Certain specified waste shall cease to be waste within the meaning of point (1) of
Article 3 when it has undergone a recovery, including recycling, operation and complies
with specific criteria to be developed in accordance with the following conditions:
(a) the substance or object is commonly used for specific purposes;
(b) a market or demand exists for such a substance or object;
(c) the substance or object fulfils the technical requirements for the specific
purposes and meets the existing legislation and standards applicable to
products; and
(d) the use of the substance or object will not lead to overall adverse
environmental or human health impacts.
The criteria shall include limit values for pollutants where necessary and shall take into
account any possible adverse environmental effects of the substance or object.
2. The measures designed to amend non-essential elements
supplementing it relating to the adoption of the criteria set out
specifying the type of waste to which such criteria shall apply
accordance with the regulatory procedure with scrutiny referred to
of-waste specific criteria should be considered, among others, at
paper, glass, metal, tyres and textiles.
of this Directive by
in paragraph 1 and
shall be adopted in
in Article 39(2). Endleast for aggregates,
3. Waste which ceases to be waste in accordance with paragraphs 1 and 2, shall also
cease to be waste for the purpose of the recovery and recycling targets set out in
Directives 94/62/EC, 2000/53/EC, 2002/96/EC and 2006/66/EC and other relevant
Community legislation when the recycling or recovery requirements of that legislation are
satisfied.
June 2006/revised June2011
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8
European Coal Combustion Products Association
4. Where criteria have not been set at Community level under the procedure set out in
paragraphs 1 and 2, Member States may decide case by case whether certain waste
has ceased to be waste taking into account the applicable case law. They shall notify the
Commission of such decisions in accordance with Directive 98/34/EC of the European
Parliament and of the Council of 22 June 1998 laying down a procedure for the provision
of information in the field of technical standards and regulations and of rules on
Information Society services (1) where so required by that Directive.
June 2006/revised June2011
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European Coal Combustion Products Association
Annex 1
Coal Combustion Products (CCPs)
- Generation and use -
Content
page
1.
Introduction
2
2.
CCPs: Production, use and requirements for the use
3
2.1
2.1.1
2.1.2
2.1.3
Bottom Ash
Generation
Properties
Use and requirements for use
3
3
3
4
2.2
2.2.1
2.2.2
2.2.3
Fly Ash
Generation
Properties
Use and requirements for use
4
4
6
6
2.3
2.3.1
2.3.2
2.3.3
Boiler Slag
Generation
Properties
Use and requirements for use
7
7
7
8
2.4
2.4.1
2.4.2
2.4.3
FBC Ash
Generation
Properties
Use and requirements for use
9
9
9
10
2.5
2.5.1
2.5.2
2.5.3
SDA Product
Generation
Properties
Use and requirements for use
10
10
11
11
2.6
2.6.1
2.6.2
2.6.3
3
FGD gypsum
Generation
Properties
Use and requirements for use
Summary/Conclusion
11
11
12
12
13
Annex
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14
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Annex 1
1
Introduction
In coal-fired electricity generating power plants solid minerals are produced during and after the
combustion of fine ground coal with and without co-combustion in a fully controlled process. The
materials under consideration are the ashes i.e. the unburnable mineral matter in the fuel
(bottom ash, fly ash, boiler slag, FBC-ash), and, where abatement equipment is fitted, the
desulphurisation products obtained from a chemical reaction between the sulphur dioxide,
which is derived from the sulphur in the coal during the combustion process, and a calcium
based absorbent, in flue gas desulphurisation installations (SDA product and FGD gypsum).
Most of the by-products are produced in so called dry-bottom furnaces, i.e. a combustion
processes with temperatures of 1100 - 1400°C. The combustion process of in a dry-bottom
furnace and the generation of coal combustion products (CCPs) is shown in figure 1.
Boiler
Chimney
NH3
DENOX
FGD
ESP
Coal
Lime
Bottom Ash
Fig 1
Fly Ash
FGD Gypsum
Production of coal combustion products (CCPs) in coal-fired power plants
A similar process (wet-bottom furnace) is used for production of boiler slag. Within this
combustion process the burning temperature is higher (1500 - 1700°C) and the fly ash normally
is fed back to the boiler where it melts again and forms boiler slag.
Fluidised bed combustion (FBC) ash is produced in fluidised circulating bed boilers at lower
temperatures (800 to 900°C).
Spray dry adsorption (SDA) product results from dry and semi dry flue gas desulphurisation,
FGD gypsum from wet flue gas desulphurisation.
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Coal Combustion Products (CCPs) - Generation and Use
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Annex 1
2
CCPs: Production, use and requirements for the use
In 2008, the amount of CCPs produced in European (EU 15) power plants totalled 56 million
tonnes and in the larger EU of 27 member states the total production is estimated to be about
100 million tonnes. Exact figures from the new member states are not available, yet.
Most of the CCPs produced are used in the construction industry, in civil engineering and as
construction materials in underground mining (54 %) or for restoration of open cast mines,
quarries and pits (36.5 %). In 2008, about 2.4 % was temporarily stockpiled for future utilisation
2
and 7 % was disposed of .
The utilisation of the coal combustion products (CCPs) depends on their chemical,
mineralogical and physical properties. These properties are influenced by the design and type
of power plant, the source and feed of fuels as well as the type of coal and secondary fuels. A
constant product quality is the major prerequisite for utilisation. Regarding this, ashes from coal
combustion have more favourable prerequisites than most ashes from lignite, whose
composition is subject to comparatively larger fluctuations. Therefore, lignite ashes are
predominantly used for reclamation of opencast mines. All other fields of application follow the
same rules as will be described for ashes from coal.
2.1
Bottom Ash
2.1.1
Generation
During the combustion of the fuel in the boiler (see figure 1), some mineralized, partly melted
particles agglomerate within the boiler and become sintered together. Owing to their weight
these particles do not pass out of the combustion chamber with the flue gas, but fall to the
bottom of the boiler, where they are either removed directly or quenched in a water bath
influencing the particle structure. This bottom ash may be processed, if necessary, by
dewatering, screening, breaking and/or grading before an interim storage (silo, pit) or loading
onto truck, train or barge at the power plant’s temporary store and dispatched to its intended
use.
Samples for quality monitoring are usually taken direct from the loading equipment at the
temporary storage facility. The nature and extent of quality monitoring depend on the area of
application. Where the bottom ash is used as a lightweight aggregate for mortar and concrete, it
typically has to comply with the requirements of European and national rules (application
standards). In earthworks and civil engineering it often has to satisfy national regulations of the
road authorities. In addition, specific requirements may be agreed between the bottom ash
producer and the user.
2.1.2
Properties
Bottom ash consists of irregularly shaped particles with a rough surface. The main chemical
components are silica, aluminium and iron oxide. The chemical composition of bottom ash is
largely comparable to that of fly ash (see 2.2). Due to its porous particle structure, bottom ash
combines low weight with good soil mechanics properties; however, its particle size distribution
may vary considerably, as it depends on the fineness of the pulverized coal and the combustion
conditions.
2
ECOBA- Statistics on Production and Utilisation of CCPs in Europe (EU 15) in 2008
June 2006/revised June2011
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Coal Combustion Products (CCPs) - Generation and Use
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Annex 1
2.1.3
Use and requirements for use
In Europe, about 5 million tonnes per annum of bottom ash is produced following the
combustion of coal and lignite. Whereas bottom ash from lignite power plants is almost entirely
used for filling worked-out open-cast lignite mines, bottom ash from coal-fired power plants is
used in other areas. The chemical, physical and mechanical properties of bottom ash and its
compliance with the relevant standards, guidelines and regulations are crucial to its use as a
building material. Some uses require further processing of the material by breaking or screening
to make it more uniform. In other cases the requirements for high-grade use are satisfied even
without additional processing steps.
In 2008, about 2.4 million tonnes of bottom ash were used in the construction industry. Out of
this 37 % was used as a fine aggregate in concrete blocks, 41 % in road construction and about
16 % in cement (see figure A1 in Annex I).
Typical uses for bottom ash, together with details of the quality requirements it must meet for
these uses, include:
•
•
for concrete blocks: EN 13055-13 and national regulations
in earthworks and road construction: according to national regulations.
In particular, the properties of bottom ash are useful:
- in open placement for the construction of roads and pathways and the creation of
industrial and storage areas,
- in landscaping and recultivation measures,
- in the construction of bound and non-bound load-bearing layers and bound base
surface layers ,
- in road sub bases and
- in the construction of noise barriers.
as lightweight aggregate for concrete products according to DIN EN 13055-12 where the
conformity evaluation has to follow a similar procedure as described in EN 450-2 for fly ash
for concrete (see Section 2.2)
as a raw material for cement clinker production: site specific requirements
as filler for cement: EN 197-14
for brick production: national regulations
for gardening and landscaping: national regulations
•
•
•
•
•
2.2
Fly Ash
2.2.1
Generation
Production of suitable quality fly ash in a coal or lignite-fired power plant is based on the
principle of pulverized fuel firing (see figure 1, page 2).
The pulverized coal with or without secondary fuels is blown with air into the combustion
chamber of the power plant boiler. Combustion (oxidation) of the fuel at a temperature of up to
1400°C produces mineralized particles which, after a residence time of up to several seconds,
leave the firing chamber with the flue gas.
1. The flue gas containing the fly ash flows through the boiler passes and also, if present, the
denitrification unit and economizer, and is then fed to the dust removal unit.
3
4
EN 13055-1: Lightweight aggregates for concrete, mortar and grout, 2004
EN 197-1: Cement - Part1: Composition, specifications and conformity criteria for common cements,
2009
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Coal Combustion Products (CCPs) - Generation and Use
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2. In the dust removal system, which usually works on the principle of electrostatic precipitation
and comprises a number of stages (cells), the fly ash is separated from the flue gas and
removed.
3. Monitoring of fly ash quality – assuming it is intended for high-grade use – takes place
between the dust removal unit and the interim storage silos. The combustion process is
controlled and material sorted depending on the monitoring findings.
4. On the basis of the results, the fly ash is stored in different silos depending on its quality
(compliance or non-compliance with standards). From there it is transported to the place of
use by road, rail or water. - If the power plant is equipped with only one silo the decision
whether the fly ash in the silo is a fly ash according to EN 450 is taken on the results of the
internal quality control.
The combustion process is fully controlled to meet stringent emission control parameters as well
as to meet the requirements resulting from European standards for conformity evaluation of the
products. Figures 2 shows the responsibilities of the producer for e.g. fly ash for concrete
5
according to the European standard EN 450-2 (formerly national standards).
production
control
scope of the production control according to EN 450-2
= responsibility of the producer / owner of certificate
boiler
responsibility
power plant operator
=
internal
quality
control
+
autocontrol
testing
Fig 2
stack
FGD
DENOX
KAT
internal
quality
control
- fineness
- LOI
auto-control
testing
ESP
fly ash
non silo 2
EN Q II
450
EN
silo 1
Q I 450
final product
fly ash
responsibility producer
Production control for the production of fly ash for concrete according to EN 450-24
The complete combustion process has to be described in a works quality manual and the
process is monitored by an officially recognized monitoring body (third party control). A similar
system for conformity evaluation is required by the European standard for lightweight aggregate
(see page 4).
5
EN 450-2: Fly ash for concrete - Part 2: Conformity evaluation, 2005
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Coal Combustion Products (CCPs) - Generation and Use
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Annex 1
2.2.2
Properties
Fly ash is a fine grained dust consisting mainly of melted vitreous particles of spherical shape
with a smooth surface. Depending on the fuel used, a distinction is made between siliceous and
calcereous fly ash. The principal components are silica, aluminium and iron compounds, and
also – in calcereous fly ash – calcium oxide or calcium compounds. The composition of
siliceous fly ashes corresponds to that of naturally occurring pozzolans (volcanic ashes), while
calcereous ashes also contain hydraulically active mineral phases in addition to pozzolanic
components. A special property of siliceous fly ash is its pozzolanic reactivity, i.e. its capacity to
react with lime and water at ambient temperature to form strength-giving mineral phases similar
to those in Portland cement. In view of its fineness and particle size distribution, and also its
pozzolanic reactivity, coal fly ash is mostly used in cement-bound building materials to improve
their technical properties and replace cement.
2.2.3
Use and requirements for use
In 2008, about 38 million tonnes of fly ash from lignite and coal combustion were produced.
Most of the fly ash from lignite combustion (about 17 million tonnes) is used for reclamation of
open cast mines, pits and quarries.
About 18 million tonnes of fly ash was used in the construction industry and in underground
mining, i.e. as concrete addition, in road construction and as a raw material for cement clinker
production. Fly ash was also utilised in blended cements, in concrete blocks and for infill (that
means filling of voids, mine shafts and subsurface mine workings) (see figure A2 in Annex I).
Typical uses for fly ash, together with details of the quality requirements it must meet for these
uses, include:
•
•
•
•
6
7
8
9
10
as addition to concrete according to EN 206-16
Fly ash is used as a concrete addition in various proportions depending on the individual
mix design, and improves the properties of concrete, e.g. by reducing the heat of
hydration, improving durability, increasing resistance to chemical attack. To some extent
it replaces cement, enabling the content of the latter to be reduced in concrete
accordingly. For this application fly ash has to be produced according to EN 450-17 and
EN 450-28.
in road construction: according to national regulations.
In addition to its use in concrete layers, fly ash is used in bituminous surface layers and
in hydraulically bound road bases. The relevant quality requirements are set out in
instruction sheets and technical requirements issued by national authorities or by
European or national standards (i.e. EN 132829)
for cement production
Fly ash is used as a raw material component (clay substitute) in cement clinker
production or as a main constituent in the production of Portland fly ash cement or
Portland composite cement. In the first case site specific requirements of the cement
producer has to be met, for the production of blended cement the requirements in EN
197-110.
for concrete blocks: national regulations
EN 206-1: Concrete – Part 1: Specification, performance, production and conformity, 2000
EN 450-1: Fly ash for concrete - Part 1: Definition, specifications and conformity criteria, 2005
EN 450-2: Fly ash for concrete - Part 2: Conformity evaluation, 2005
EN 13282: Hydraulic Road Binders, Composition, specifications and conformity criteria, 2009
EN 197-1: Cement - Part 1: Composition, specifications and conformity criteria for common cements,
2009
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Annex 1
•
•
•
•
for infill, that means filling of voids, mine shafts and subsurface mine workings according to
national regulations of the mining authorities
for production of bricks (leaning of fatty clay): national regulations
in earthworks and landscaping
In earthworks and landscaping the mechanical properties of fly ash are used in setting up
and improvement of road foundations (embankments), the construction of noise barriers,
and for recultivation and soil improvement.
for production of mortar, floor screed and plasters and mining mortars/civil engineering
products: national standards and requirements
In line with the energy demand curve and the seasonal working load of coal-fired power
stations, fly ash is largely produced during the colder months of the year when business in the
building industry is slack. Silos with a capacity of up to 60,000 tonnes have therefore been built
at some power plants to provide dry temporary storage facilities for fly ash prior to its use as a
concrete addition. In some cases, certified fly ash in particular is stored in a moistened state
during the winter months, before being re-dried in separate facilities in the summer months for
subsequent use in the building materials industry.
2.3
Boiler Slag
2.3.1
Generation
Boiler slag is produced when coal is burned in slag-tap furnaces. In such furnaces the ash
components are drawn off in a molten state at very high temperatures (1500 - 1700°C) and
subjected to sudden quenching in a water bath (see figure 3). The individual process steps are:
1. Pulverized coal is blown by a transporting air stream into the combustion chamber of the
power plant boiler.
2. In the combustion chamber, temperatures of over 1500ºC lead to liquid slag which is
discharged at the bottom of the boiler.
3. The flue gas containing the fly ash flows through the boiler passes and also, if present, the
denitrification unit and economizer, and is then fed to the dust removal unit. In the dust
removal system, which usually works on the principle of electrostatic precipitation and
comprises a number of stages (cells), the fly ash is separated from the flue gas and either
conveyed to fly ash storage silos or fed back to the boiler.
4. The sudden quenching of the molten material flowing from the melting chamber into the
water bath results in the formation of typical glassy (amorphous) grit-like granules.
5. The boiler slag granules are transported from the water bath to the dewatering unit, via a
special filter bed if necessary.
6. After any necessary processing in the form of grading and breaking, the dewatered material
is conveyed to the in-plant storage area. From here it is transported in batches to the
intended uses.
Samples for quality monitoring are usually taken direct from the loading equipment at the
temporary storage facility. The nature and extent of the quality monitoring depend on the
intended use of the vitrified slag.
2.3.2
Properties
Boiler slag is a glassy material, has a broken particle shape due to the production process, and
has a particle size of 0.2 to 11 mm. Special features of the granules are their low apparent
density and installation weight, high angle of friction, excellent frost resistance, lack of sensitivity
to environmental influences, high permeability and good filtering effect when used in beds.
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Coal Combustion Products (CCPs) - Generation and Use
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The properties of processed boiler slag meet the requirements of normal size fractions, such as
0/5 high quality broken sand (natural sand classified for grain diameter of 0 to 5 mm).
Boiler slag does not contain any organic impurities. All trace elements are firmly and
permanently embedded in the glass matrix. Systematic tests have shown that leaching of
vitrified slag does not release any substances harmful to the environment.
Boiler
Chimney
NH3
DENOX
FGD
ESP
Coal
Lime
feed of Fly Ash
Fig. 3
Boiler Slag
Production of Boiler Slag
2.3.3
Use and requirements for use
FGD Gypsum
The chemical, physical and mechanical properties of boiler slag and its compliance with the
relevant standards, guidelines and regulations are crucial to its use. For some uses, further
processing of the material by breaking or screening makes it more uniform.
In 2008, about 1.4 million tonnes of boiler slag were produced in Europe (EU 15). The utilisation
rate was 100 %. About 45 % was used as blasting grit, about 30 % in road construction, 10 %
was used as aggregate in concrete and about 5 % for grouting and drainage (see figure A3 in
Annex I).
Typical uses for boiler slag, together with details of the quality requirements it must meet for
these uses, include:
•
•
•
•
•
•
•
for road construction: national regulations
Boiler slag is used in road pavement, as bed material and joint pinning, infill of rural tracks,
car parks and pathways.
as blasting grid for surface treatment of metal and concrete11
for concrete production : EN 1262012 and national regulations
for bricks: national regulations
in earthworks: national regulations
Boiler slag is used for soil improvement, as filter material for drainage, as backfill material
and as a bed material
in road construction: national regulations
Boiler Slag is used for road pavement, as bed material, for joint pinning, infill of rural tracks,
car parks and pathways.
for drainage material and filter course on landfill sites: national regulations
11
ISO 11126-4: Preparation of steel substrates before application of paints and related products Specifications for non-metallic blast-cleaning abrasives - Part 4: Coal furnace slag, 1998
12
EN 12620: Aggregates for concrete, 2008
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2.4
Fluidized bed combustion (FBC) ash
2.4.1
Generation
Fluidized Bed Combustion (FBC) ash is produced in fluidized bed combustion boilers. The
technique combines coal combustion and flue gas desulphurisation in the boiler at combustion
temperatures of 850 to 900°C (see figure 4). The individual process steps are:
1. Pulverized coal and milled limestone for desulphurisation is fed to a fluidized bed
combustion boiler. The fluidized bed consists of sand like material which is fluidized by
addition of air from the bottom of the boiler.
2. In the fluidized bed coal and limestone are intimately mixed and heated up to a temperature
of 850 to 900°C. By this, the coal is burned, the limestone is decomposed and reacts with
the sulphur from coal combustion.
3. The minerals formed by coal combustion differ in size and density. The bigger particles are
removed from the fluidized bed as bed ash, the finer particles leave the firing chamber with
the flue gas, also the flue gas desulphurization products and unreacted adsorbens. In the
dust removal system, either cyclones, baghouse filters or electrostatic precipitators, fly ash is
collected and conveyed to storage silos or mixed with the bed ash and stored in silos or
interim storage sites.
FBC ash is stored temporarily before undergoing final controls and being transported to the
place of use, usually by road.
Cyclone
Furnace
850 –
900°C
Lime
ESP
Coal
Bed material
Bed cooling
Bed Ash /
Bottom Ash
Fig. 4
2.4.2
Fly Ash
Production of FBC ash
Properties
Depending on the desulphurisation process in the furnace FBC ash, as a mix of bed ash and fly
ash, consists of coal ash, residual coal, desulphurization products and non reacted adsorbent.
The comparatively low combustion temperature lead to formation of fine grained crystalline
minerals. The maximum grain size is up to 10 mm stemming from bed ash particles. The ash is
rich in lime and sulphur due to the combined desulphurisation process. Other main chemical
constituents are silicon, aluminium and iron oxide.
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Coal Combustion Products (CCPs) - Generation and Use
Annex 1
2.4.3
Use and requirements for use
The amount of FBC ashes produced in Europe (EU 15) was about 1.0 million tonnes in 2008.
The production has to be considered small compared to the production in Poland and the Czech
Republic. In 2008, about 0.2 million tonnes of the FBC-ash produced in EU 15 member states
was used for engineering filling applications (52 %), for structural fill (11 %) and infill (9 %) (see
figure A4 in Annex I).
The typical uses for FBC ash, together with details of the quality requirements it must meet for
these uses, are based on national regulations.
2.5
SDA product
2.5.1
Generation
With the desulphurisation of flue gases in European power plants using spray dry absorption
techniques spray dry absorption product (SDA product) is generated. The desulphurisation
process involves the following process steps within the plant:
1. The lime suspension introduced into the spray absorber reacts with the sulphur dioxide
(SO2) present in the flue gas.
2. The process temperatures are adjusted so that the water present in the system evaporates
completely and the reaction product (normally SDA product) is output in a dry state at the
dust removal units.
3. The finished SDA product is temporarily stored on site and transported from there to the
user.
Depending on the location of the SDA installation in the flue gas stream (upstream or
downstream the electrostatic precipitator) SDA product may contain fly ash up to 60 % by mass
(see figure 5, case I or II). This has a major influence on its further use.
SDA product is stored temporarily in silos before undergoing final controls and being
transported to the place of use, usually by road.
Desulphurization (DeSOx)
Lime
Boiler
I)
ESP
SDA
Fly ash
+ SDA product
Coal
Lime
II)
ESP
SDA
Bottom Ash
Fly ash
Fig. 5
SDA product
Production of SDA Product
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Coal Combustion Products (CCPs) - Generation and Use
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Annex 1
2.5.2
Composition and properties
SDA product is a fine-grained powder with a particle size mostly less than 60 µm and a residual
moisture content of less than 10% by weight. Depending on the fly ash content, its colour varies
from white to grey.
Owing to differences in process technology (with (II)/without (I) prior dust removal) and in the
properties of the fuels and auxiliary agents used, the composition of the SDA product may
fluctuate within a wide range. The SDA product is a mixture of the following minerals: calcium
sulphite hemi-hydrate, calcium sulphate di-hydrate (gypsum), calcium carbonate, calcium
hydroxide, calcium chloride and calcium fluoride.
2.5.3
Use and requirements for use
In 2007, about 0.4 million tonnes of spray dry absorption product (SDA product) were produced
in European power plants (EU 15). No systems with spray dry absorption are in use in lignite
power stations. The production has to be considered small compared to the production in
Poland and Czech Republic.
About 0.2 million tonnes of the SDA product produced in EU 15 member states was mainly
used in filling applications (structural fill and infill). About 3 % was used for plant nutrition and
about 20 % as a sorbent in wet FGD (see figure A5 in Annex I).
The excellent fertilizer effect of the calcium and sulphur in SDA product is used in agriculture
and forestry. In Germany, SDA product is listed in the Fertilizers Ordinance as a fertilizer type in
its own right. The resulting requirements are satisfied by SDA products from systems equipped
with prior dust removal.
The typical uses for SDA product, together with details of the quality requirements it must meet
for these uses, are based on national regulations.
2.6
FGD gypsum
2.6.1
Generation
FGD gypsum is produced in the flue gas desulphurisation process of coal-fired power plants
incorporating the desulphurisation of the flue gas in the power plant (see figure 1) and a refining
process in the FGD plant including an oxidation process followed by gypsum separation,
washing and dewatering.
The process involves the following sequence of process steps within the plant:
1.
2.
3.
The suspension containing limestone/chalk (CaCO3) or quicklime (CaO) which is sprayed
into the flue gas scrubber reacts with the sulphur dioxide (SO2) present in the flue gas to
form mainly calcium sulphite (CaSO3). This results in a liquid mixture, the solid
components of which are calcium sulphite and the calcium sulphate circulated in the
scrubber cycle.
Calcium sulphite is oxidized by adding defined quantities of air, and in the subsequent
crystallization process it binds two molecules of water; this results in a suspension of
gypsum (calcium sulphate dihydrate: CaSO4 ⋅ 2H2O) in the scrubber sump.
In the further course of the process the gypsum suspension, which is monitored internally
to track its chemical and physical properties, now passes through hydrocyclones where
partial dewatering takes place and the gypsum particles are graded. The fine material is
returned to the flue gas scrubber.
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Annex 1
Further dewatering and purification of the gypsum with leaching of water-soluble
components (e.g. chloride) takes place either in a centrifuge or on a belt-type vacuum
filter. The washing water undergoes further reprocessing in a separate unit. The residual
moisture content of FGD gypsum (excluding bound crystal water) is between 5 and 12%.
The finished FGD gypsum, which may be dried first, goes to an on-site interim storage
facility (silo, hall). From there it is transported to the user by water, road or rail. (A certain
amount of the FGD gypsum produced in Germany goes to raw material depots to ensure
continuous long-term supplies to the gypsum industry.)
4.
5.
The quality of the gypsum is monitored daily. The samples are taken immediately before the onsite interim store. The laboratory tests are performed in accordance with the instruction sheet
“FGD gypsum – Quality Criteria and Analytical Methods”13 and any additional parameters
agreed between producer and customer.
2.6.2
Properties
FGD gypsum is a moist, fine-grained material with a residual moisture content of 5 to 12 % and
at least a 95 % concentration of CaSO4 ⋅ 2H2O. Depending on the production conditions, the
gypsum crystals are needle-shaped to compact and plate-like.
The composition and properties of FGD gypsum are identical to those of natural gypsum, as
has been proven by extensive basic scientific research14.
2.6.3
Use and requirements for use
The amount of FGD gypsum produced in Europe (EU 15) was approximately 11 million tonnes
in 2008. More than 80 % of the total FGD gypsum produced in Europe is utilised in the gypsum
and cement industry. In total, about 3 % of the FGD gypsum produced was temporarily
stockpiled as a raw material base for future utilisation, mostly for plasterboard production, and
about 7 % was disposed of.
FGD gypsum is used as a raw material for a number of gypsum products by the gypsum
industry because of its purity and homogeneity compared to natural gypsum. 5.6 million tonnes
of FGD gypsum was used in 2008 for the production of plaster boards. Other applications
include the production of gypsum blocks, projection plasters and self levelling floor screeds (see
figure A6 in Annex I).
Like natural gypsum, FGD gypsum has to be dewatered by thermal means before being used
for building materials, and in this process the crystal water is completely or partially removed.
Before the gypsum product is used on the construction site or at the gypsum works, water is
added to it again, starting a controlled setting process.
FGD gypsum is also used as a retarder in cement production and as a filler in the production of
paints, adhesives and plastics. Further application exist in agriculture, where FGD gypsum is
used as a source of lime and sulphur in fertilisers, composts and soil improvers.
13
14
EUROGYPSUM: FGD Gypsum - Quality Criteria and Analysis Methods (status: April 2005).
Becker, J., Einbrodt, H.-J., Fischer, M.: Vergleich von Naturgips und REA-Gips, Bericht und gutachterliche Stellungnahme, VGB Forschungsstiftung und Bundesverband der Gips- und Gipsbauplattenindustrie e.V., 1989.
(see also: Becker, J., Einbrodt, H.-J., Fischer, M.: Comparison of Natural Gypsum and FGD Gypsum,
Abridged version of VGB Research Project 88, VGB Kraftwerkstechnik 1/1991, p. 46-49
June 2006/revised June2011
20
Coal Combustion Products (CCPs) - Generation and Use
21
Annex 1
Typical uses for FGD gypsum, together with details of the quality requirements it must meet for
these uses, include:
•
•
3.
for use as a raw material for the gypsum and cement industry: FGD Gypsum Quality
Criteria15
for the use as fertiliser: national regulations.
Conclusion
In Europe (EU 25), more than 100 million tonnes of by-products were produced in coal-fired
power stations in 2008; of this total, about 56 million tonnes was produced in the EU 15
countries. The by-products include boiler slag, bottom ash and fly ash from different types of
boilers as well as desulphurisation products like spray dry absorption product and FGD gypsum.
Out of the total production of 56 million tonnes of by-products in EU 15, the amount of ash
produced was around 44 million tonnes, while around 12 million tonnes are products obtained
from flue gas desulphurisation processes.
The by-products are mainly utilised in the building material industry, in civil engineering, in road
constructions, for construction work in underground coal mining as well as for recultivation and
restoration purposes in open cast mining. Most of the hard coal fly ashes are used in cement
and concrete.
In the majority of cases by-products are used as a replacement for natural materials and
therefore offer environmental benefits by avoiding the need to quarry or mine these resources.
By-products also help to reduce energy demand as well as emissions to atmosphere, for
example CO2, which are needed for - or result from - the manufacturing process of the products
which are replaced.
All by-products are produced in a fully controlled combustion and/or desulphurisation process.
The majority of the by-products is produced to meet certain requirements of standards or other
specifications with respect to utilisation in certain areas. To meet the demand of the customers
by-products may have to be stored for a certain interim period or processed. Interim storage is
necessary because by-products are produced in wintertime when construction work is rare.
Storage facilities guarantee stable product qualities until final use. For special products also
processing of by-products may be required to allow the benefit of specific by-product use also in
products with special properties.
15
EUROGYPSUM: FGD Gypsum - Quality Criteria and Analysis Methods (status: April 2005)
June 2006/revised June2011
21
22
Coal Combustion Products (CCPs) - Generation and Use
Annex 1
Annex I
Road Construction,
Filling Application
Concrete
Addition
Concrete Blocks
32.6%
41.2%
5.5%
Others, 1.8%
37.0%
Blended
Cement
22.7%
15.5%
Cement/
Mortar
Concrete
Blocks
Concrete, 2.7%
Figure A1:
Utilisation of Bottom Ash in the Construction
Industry and Underground Mining in Europe
(EU 15) in 2008.
Total utilisation 2.4 million tonnes.
10.6%
Infill, 2.5%
Others, 1.0%
Cement
Raw Material
Figure A2:
Utilisation of Fly Ash in the Construction
Industry and Underground Mining in Europe
(EU 15) in 2008.
Total utilisation 17.7 million tonnes.
52.6%
Concrete
9.6%
44.5%
21.8%
General
Engineering
Fill
Others
Blasting
Grit
Road
Construction,
Filling
Application
13.9%
11.0%
4.9% Grouting,
Drainage
5.8%
30.4%
Road
Construction
Figure A3:
Utilisation of Boiler Slag in the Construction
Industry and as Blasting Grid in Europe (EU
15) in 2008.
Total utilisation 1.4 million tonnes.
9.2%
18.5%
Infill
Subgrade
Stabilisation
Cement, 2.9 %
Other Uses (sludge treatment, waste stabilisation,..)
Figure A4:
Utilisation of FBC Ash in the Construction
Industry and Underground Mining in Europe
(EU 15) in 2008.
Total utilisation 0.2 million tonnes.
Plaster
Boards
Structural
Fill
Structural
Fill
Gypsum Blocks, 3.4%
Infill
56.6%
20.4%
62.8%
17.4%
3.4%
Self Levelling
Floor Screeds
Plant
Nutrition
7.2%
19.6%
Set Retarder
9.2%
Other uses
(wet FGD, ...)
Figure A5:
Utilisation of SDA-Product in the Construction Industry and Underground Mining in
Europe (EU 15) in 2008.
Total utilisation 0.3 million tonnes.
June 2006/revised June2011
Projection Plaster
Figure A6:
Utilisation of FGD gypsum in the Construction
Industry in Europe (EU 15) in 2008.
Total utilisation 8.8 million tonnes.
22
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