TO:		Docket no.EPA-HQ-OAR-2007-0877

	

FROM:	Mike Laney, RTI

DATE:	May 23, 2008

SUBJECT:	Use of Synthetic Gypsum at Holcim Plants with Wet Scrubbers

A conference call was held on May 15, 2008 between representatives from
EPA and Holcim (US) Inc. to discuss their use of gypsum created as a
byproduct of their wet scrubber operations. This memorandum summarizes
the key points from that call. The following individuals participated in
the conference call:

Holcim

Meg Garakani

Joel Bolduc, Portland, CO

Dick Rausch, Quality Manager, Portland, CO

EPA

Keith Barnett

RTI

Mike Laney

Summary

Scrubber pH control – The Portland facility uses 100% CKD to control
scrubber pH. Purchased lime has been used but is much more expensive.

Synthetic gypsum – All of the synthetic gypsum from the scrubber is
used to mix with the ground clinker. The synthetic gypsum represents
about 10% of their total gypsum use.

Purchased gypsum – Gypsum is purchased from Oklahoma and is relatively
expensive. Holcim has recently purchased a gypsum mine and will be
switching to this source in the future. This will reduce their costs for
purchased gypsum.

Purchased gypsum cost at the Portland  facility – The price for gypsum
is around $45/short ton. Three-fourths (3/4) of the gypsum costs are
transportation costs. As a result, prices for gypsum can vary
significantly.

Nationwide, costs for gypsum can be as low as $30/short ton and as high
as $55-$60/short ton

Product quality – The CaSO4 quality of Portland’s synthetic gypsum
is fairly good. The fineness of the synthetic gypsum creates
difficulties in de-watering and handling. Even after de-watering, the
gypsum has high moisture content. There is also enough ammonia in the
gypsum that there is an ammonia odor in the finish silo. The ammonia
occurs naturally in the raw materials.

