Resource Stream
Clay Brick
By Bob Fromtling
Resource Acquisition
Materials Required:
clay, sand, fuel (varies),
and manpower.
 Clay is extracted/mined
from clay quarries
 Soil must contain from
25 to 50% clay and silt
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Copyright 1997 Haruhiko Suga
Environmental Impacts of
Extraction
New extraction sites can have adverse impacts
on local landscape, habitats, animals, and plants
 Quarrying process produces silt laden waters
that can escape through storm runoff to
contaminate surrounding surface and ground
waters
 Clay particles also enter the air surrounding a
quarry
 Many extraction sites are used as landfills after
the clay has all been extracted, which has
significant environmental impacts
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Brick Production
The clay soils are mixed with water for plasticity
and sand to keep them from sticking to the brick
molds
 The material is then extruded through a large
opening making a sheet that can be cut into
bricks
 Through new Stiff Extrusion technology, the
bricks contain much less moisture, shortening
the drying and heating processes and reducing
the wastage of bricks through handling
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Production Continued
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After being cut, bricks are
stacked and dried, either by
open air or by the excess
heat from the brick kilns
Once they have dried
sufficiently to remove
moisture, the bricks are heat
treated
It is through this heating that
the alkalis in the clay and the
oxides from iron and other
metals join with the alumina
and silica in the clay to give
the bricks their desired
hardness
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Production: Kilns
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A kiln is an oven or furnace where bricks are fired or
heat treated to develop their hardness
Brick production is a very energy intensive process and
large amounts of fuel must be burned to acquire the
correct hardness in the bricks
Openings are left in the kiln to release the combustion
gases and pieces of metal can be slid on and off of these
openings to control the rate at which the fire burns
Depending on the technology being used the fuels for a
kiln vary from wood and charcoal (most commonly) to
natural gases or even waste materials, such as sawdust,
pecan shells, plastic wastes, agricultural wastes, and
scrap tires
Kilns Continued
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Depending on fuels used,
the heating process can
go on from anywhere
between 17 hours and 8
days and the prime heat
level is about 885°
Celsius
If the fuel runs out and
the temperature falls
under the correct level,
the entire load of bricks
could be lost
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Environmental Impacts of
Production
The dangerous pollutants emitted by brick
kilns are numerous and varied
 These emissions are produced from the
burning of the fuels as well as from the
bricks themselves as they are heated
 These emissions can be extremely
unhealthy to kiln workers as well as the
surrounding flora, fauna, and residents
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Environmental Impacts: Air
Pollutants
Nitrogen oxides are produced by the
burning of hydrocarbon fuels and cause
acid rain as well as local air pollution
 Sulfur dioxides are produced by the
heating of the clay and the burning of any
oils or coals as a fuel source
 Carbon monoxide and carbon dioxide are
produced when hydrocarbon fuels are
burned and CO causes local air pollution
while CO2 causes global warming
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Air Pollutants Continued
Other organic compounds, even toxins
such as dioxin can be released if waste
compounds are used to fuel a kiln
 Particulate matter is produced by the firing
of the bricks themselves and from the
burning of heavy fuel oil, coal, and waste
materials
 Many of these problems could be greatly
remedied and reduced by the use of
better technology, which reduces waste
and increases efficiency
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Disposal
The only options in brick disposal are landfills or
recycling
 Bricks are often moved to landfills where they
serve no purpose other than to take up space
 Bricks can be recycled in a variety of ways
ranging from being reused as whole bricks in
future construction projects to being crushed
and graded for use in road construction,
driveways, or as sand or river gravel
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Environmental Impacts of Disposal
The only problem with the disposal of
bricks is when they are put into landfills
 Recycling is an excellent cost efficient way
to reduce the amount of brick material
that ends up in landfills
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Ways to Increase Energy Efficiency
and Reduce Waste
Brick kilns use a large amount of energy
and emit a large amount of pollutants
 By using new and inexpensive technology
both of these factors can be significantly
improved
 In India the brick industry is huge and
steps are being taken to improve their
emissions and energy use
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Vertical Shaft Brick Kilns
VSBK save between 30 and 50% more
energy than traditional brick kilns
 Because of its roof VSKB can operate in all
weather conditions year round instead of
only 6 months per year
 Because of energy efficiency and improved
combustion air flow efficiency the amount
of suspended particulate matter in the
emitted flue gases and other pollutants
are greatly reduced
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Vertical Shaft Brick Kiln: Statistics
and Picture
Property of Teri
Organization
Other Simple Means of Increasing
Environmental Performance
By drying the bricks for extended periods of time fuel
requirements are reduced
 By preheating kilns with cleaner burning propane or
natural gas before switching to waste fuels such as
sawdust, production speed and quality can be increased
 By simply raising the bricks on a metal grill above the
fuel, air flow and combustion increase, reducing
particulate matter and other emissions
 By reducing air leaks and controlling the size of the kiln
opening, combustion can be improved, hence leaving
less partially burned fuels
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Environmental Benefits of Brick
Production
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Fly-ash is a byproduct of the burning of soft coals such
as Bituminous coals. It consists of the lighter particles of
ash that fly into the air, hence the name
Fly-ash is a known carcinogen and can cause skin and
lung diseases. It also reflects infra-red rays, contributing
to global warming. It is being produced in huge
quantities in such countries as India and Australia, who
both have large brick industries
If stiff extrusion technology is used, maximum amounts
of non-plastic (clay) material can be used
With this technology 30-60% of fly-ash can be used in
the production of bricks. This is a wonderful way to
recycle a substance that has no other use, is very hard
to dispose of, and has terrible environmental and health
effects
Sources Used
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http://www.teriin.org
http://www.hinduonnet.com/thehindu/mp/2002/
/10/07/stories/2002100701530400.htm
http://www.priyabrick.com/mbp.htm
http://www.cleanerproduction.com/sectors/subs
ectors/clay.html
http://www.fao.org/inpho/vlibrary/s1250e/S1250
E07.htm
http://www.ebrd.com/about/policies/enviro/sect
oral/construc/brick.pdf
http://www.scerp.org/scerp/projects/AQ95_9.ht
ml