[USCC] Gypsum

[Chaney, Rufus]

Dear Colleagues:

There is a great interest in beneficial use of gypsum from treatment of
coal fired power plant exhaust to remove sulfur dioxide. For many years
much of this gypsum was used in producing wallboard, but that market is
saturated, and new construction has declined as well. Further, the
extent of exhaust treatment across the country is increasing, so more
FGD-gypsum is becoming available for use. Several groups of University
and USDA scientists are working with the electric power industry to
investigate uses of FGD-gypsum and assess the benefit and risks of this
practice.

Low rates of FGD-gypsum application can aid water infiltration, reduce
clay dispersion, reduce phosphate runoff, and some additional beneficial
effects. It is also a sulfur and Ca fertilizer, and replaces mined
gypsum for peanut production among other uses.

The coal-power industry has produced several types of FDG-gypsum in the
past, but is moving to produce a relatively high purity product by doing
the SO2 removal after electrolytic removal of fly ash. Some earlier
methods used the SO2 scrubber to remove fly ash and generated a
byproduct with about 50% limestone equivalent, but much of the trace
elements from fly ash. Depending on the coal source burned, that product
could be rich in boron, arsenic, selenium or some other trace elements.
But the new Gypsum from FGD treatment has only low levels of trace
elements. Study is continuing in cooperation with US-EPA in a program to
develop a risk assessment for beneficial use of the FGD-Gypsum. 

Like many other sources of byproducts, I believe that wallboard wastes
and FDG could be included in composting feedstocks at rates that were
beneficial to the quality of the compost product. For composts to be
used to treat saline soils, gypsum inclusion could be especially
beneficial. Keep in mind the different processes of gypsum production
when considering gypsum byproduct use.

Rufus Chaney
Beltsville, MD

-----Original Message-----
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Sent: Monday, November 10, 2008 1:55 PM
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Subject: [USCC] Gypsum

To All:

I have a grant proposal that is proposing a beneficial reuse of wall
board, by mixing the ground gypsum product with compostable materials. I
have been asked by the project team reviewing the grant proposal if any
has done this? If so, has anyone tested the final product?

I have heard inklings of projects like this, but do not know of anyone
who has actually done this. Any info any of you might have would be
greatly appreciated.

You can e-mail me, or call at 651-215-0284.

Ginny
Minnesota Pollution Control Agency
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