We've run everything inside the walls of the Project House that needs to go
there — plumbing, electrical wiring, video, telephone and computer wiring,
air conditioning ducts and vents and finally, insulation — and now it's time
to apply the wallboard to create the home's interior walls and seal it all up.
We're using SYNTHETIC Gypsum wallboard from Temple Gypsum.
Gypsum wallboard is also commonly known as "drywall".
Gypsum Defined
Naturally occurring gypsum is a generally white or gray compound that was formed
when highly saline ancient oceans deposited minerals on the ocean floor over
hundreds of millions of years. Because it is plentiful, relatively lightweight
and has a very low thermal conductivity, it is the preferred material for use
in manufacturing wallboard.
The scientific name for gypsum is "hydrated calcium sulfate". The
chemical composition is CaSO4-2(H20).
Gypsum is one of the most widely used minerals in the world. It is used in
concrete and is also used to condition the soil in vast tracts of land being
prepared for development in suburban areas. Most of the gypsum in the United
States is used to make wallboard for homes, offices, and commercial buildings.
In fact, in the average American's everyday environment, gypsum is virtually
everywhere.
Synthetic Gypsum in the Project House
The gypsum wallboard we're using in the Project House is not natural, but SYNTHETIC
gypsum that has been created from byproducts of the energy generation process
at the Tennessee Valley Authority's Cumberland power plant. It is the chemical
equivalent to natural gypsum, but maintains a consistently smaller particle
size than natural gypsum. This gives the synthetic gypsum highly predictable
and consistent performance characteristics, as Michael demonstrated in our story.
This gypsum wallboard has been certified to contain at least 99 per cent recycled
material on a dry weight basis. Even the paper is recycled, making this synthetic
gypsum wallboard super-environmentally friendly.
How Temple Gypsum's Synthetic Gypsum is Formed*:
- At the power plant, coal is pulverized into a fine powder.
- To provide the energy that drives the generation of electricity, coal powder
is blown into the furnace and burned. During the burning process, the coal
is mixed with air and the combustion process releases all of the chemicals
as well as the unburned dirt and clay locked up in the coal. Ash is formed
from the unburnable portion of the coal.
- Some of the chemicals, such as sulfur, are released and the unburned dirt
and clay are carried through in the flue gas.
- Fly ash is collected in the precipitators by electric currents that attract
the ash to wires.
- Fly ash falls into hoppers and is removed and stored in silos for use by
the cement industry.
- Limestone rock (or calcium carbonate) is finely ground with water to form
a slurry.
- Limestone slurry is stored so that it can be pumped to the scrubber as
needed. Limestone slurry is converted to gypsum slurry in the scrubber.
- Limestone slurry is delivered as a fine spray near the top of the scrubber
where it comes in contact with the flue gases from the furnace. Due to the
sulfur content of the coal burned, these flue gases contain sulfur dioxide
as a gas. The limestone slurry reacts with the sulfur dioxide in the flue
gases to form calcium sulfite initially. Air forced through the system forces
the chemical reaction from calcium sulfite to calcium sulfate, which is chemically
the same as natural rock gypsum. As crystals of calcium sulfate or gypsum
form in the scrubber, these heavier crystals sink toward the bottom of the
tank where they are continuously pumped out into the effluent slurry tank.
- The gypsum slurry is pumped through a series of lines to a valve station.
- At the valve station the gypsum slurry can be routed to storage or to de-watering.
Synthetic materials are delivered to a processing plant where the slurry
is de-watered on a series of vacuum belt filters from a solution that is about
85% water to a manageable material that is about 5-7% free moisture.- Synthetic gypsum is transferred to the storage area.
*Source: Temple Gypsum
The synthetic gypsum is then transferred to the Temple Gypsum plant on a series
of conveyor belts, and the wallboard manufacturing process begins, as seen in
the story on our show and in the Internet "video vignette".
Contact Information:
Temple Gypsum
(800) 231-6060 |
