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Reducing the Environmental
Impacts of Coal Use
Continuous improvements in technology have dramatically
reduced or eliminated many of the environmental
impacts traditionally associated with the use
of coal.
Some of the developments and measures being undertaken
in the vital electricity generation and steelmaking
industries are outlined below:
Electricity Generation
Reducing emissions of oxides of sulphur
and nitrogen...
Modern power station technology is capable of
reducing emissions of oxides of sulphur and nitrogen
(SOx and NOx) and of particulates
to meet stringent environmental requirements.
 By
treating flue gases, virtually all (99.5 per cent)
of particulate matter can be removed. This is
also the means by which a high proportion (over
90 per cent) of sulphur is prevented from reaching
the atmosphere as sulphur dioxide.
Pictured: Mount Piper Power
Station, NSW, Australia. Clean combustion - water vapour clouds billowing
out of cooling towers soon dissipate - often mistakenly thought to be pollutants.
Flue gas desulphurisation (FGD) is one means
of meeting strict emission regulations when high
sulphur coals are used. However, in many circumstances
the most economical means of sulphur dioxide control
is to use low sulphur coal. Australian export
thermal coals are well suited to this strategy.
Reducing Greenhouse Gas emissions...
Australia's electricity generators
are keen to take on the world in achieving cleaner
fossil fuel energy supply by agreeing to maximise
their efficiency and aiming to achieve global
best practice.
All of the largest electricity generators
have agreed to sign on to the Australian Government's
voluntary generator efficiency standards (GES)
program, with the smaller generators expected
to sign up shortly also.
With around 90 percent of national
energy generating capacity now covered by GES,
Australia has taken another significant step forward
in its commitment to meeting its Kyoto Protocol
target. The GES program aims to reduce greenhouse
gas emissions from electricity supply by as much
as four million tonnes of CO2 equivalent by 2010,
a saving that is equated to removing one million
cars from Australia's roads. Some companies have
already indicated that they might be able to achieve
even greater savings than expected.
While commitment to the program
is voluntary, companies sign a deed of agreement
with the Federal Government and become legally
committed over the next five years to taking actions
to reduce greenhouse gases. A plan of action will
be developed, through agreement at different stages
with the Australian
Greenhouse Office. The first stage will involve
a draft strategic plan which identifies actions
that can be undertaken to achieve best practice
performance. Feasibility studies of identified
options will then be undertaken and an action
plan developed which will be implemented within
five years.
Companies have a range of options
on how they can help meet their obligations under
the program. These range from improving the combustion
control of boilers to rebuilding air heaters.
But there will also be benefits to generators
and the economy as a whole. Individual generators
stand to gain significantly through cost savings
from improved efficiencies. It is estimated that
generators are likely to invest around $240 million
in new plant and equipment to complete the actions
identified in their strategic plans.
These costs, however, are likely to be recovered
by an anticipated $250 million saving achieved
through improved operational efficiency. There
will be benefits to Australia as it develops world
leadership in energy efficiency - which is already
occurring in the area of improving combustion
control of boilers and in job creation and investment
opportunities.
(Source: Electricity
Supply Magazine - February 2002. Electricity
Supply Association of Australia Limited)
Further information on reducing
emissions and environmental impacts in electricity
generation is provided in the Clean
Coal section.
Iron and Steel
Making
In blast furnace ironmaking, coke
consumption has been reduced to a third of what
it was 80 years ago, as have carbon dioxide emissions.
Research aimed at improving the chemical reactivity
of coke is likely to allow the widespread use
of new direct combustion technologies (the direct
reduction of iron ore to iron in the one process
and one chamber) in the near future.
 The
next generation of ironmaking furnaces is likely
to be operated without coke, using 100 percent
directly injected non-coking coals.
One such technology, the HIsmelt® process
being tested in Kwinana, Western Australia, avoids
the associated emissions from coke ovens and is
significant for sustainable development because
it accepts lower grades of iron ore than the blast
furnace, does not require premium coals and has
the potential to reduce the cost to end users.
HIsmelt® Kwinana facility
Western Australia
HIsmelt® is a Direct Ironmaking process, in
which iron ore fines and/or other iron containing
materials and ordinary steaming coals are injected
directly into a molten iron bath to produce a
quality molten pig iron. It can be considered
both as a potential replacement for the blast
furnace and as a new source of low cost iron units
for the Electric Arc Steelmaking industry.
There are substantial environmental
benefits to the HIsmelt® technology when compared
to the conventional coke oven/sinter plant/blast
furnace ironmaking route. They include:-
- Use of lower grade and lower
value iron ore fines, thereby minimising waste
and contributing to the greater sustainability
of iron ore mining;
- Elimination of environmentally
unfriendly coke ovens, sinter plants and pellet
plants; which are under increasing pressure
from environmental regulatory agencies;
- High energy efficiency, due
to minimal raw material preparation requirements,
which leads to better greenhouse gas performance;
- No emissions of dioxins,
furans or polycyclic-aromatic hydrocarbons (PAH's
eg tars and phenols);
- Ability to utilise most steel
plant wastes as a process input enabling iron
and steel plants to move closer to the goal
of Zero Waste;
For further details visit Rio Tinto's HIsmelt website at:
http://www.hismelt.com.au
Other emerging coal based technologies
which offer improvement in operating efficiency,
economics, and in reducing environmental impacts
- particularly in relation to emissions, include:
- ITmk3 - a variant
of the current FASTMELT technology, where the
coal-ore pellets are heated until partially
melted. This allows hot screening to remove
gangue from iron product.
- Tecnored - shaft furnace
technology for producing BF type hot metal using
coal-ore cold-bonded pellets.
Descriptions of these and similar technologies can be found at:
http://www.midrex.com/
http://www.chemlink.com.au/dri.htm
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