Sheetrock is one of the more vexing construction materials to deal with. Used sheetrock is problematic because of the paint that is on the surface. Some will have lead and all of it creates an issue for reuse as gypsum for new rock because of the color. There is no longer anyone in the Metro Portland area that recycles sheetrock. We currently accept sheetrock as non-recoverable waste only. The closest facility that is currently engaged in recycling is near Seattle, which is currently cost prohibitive because of transportation costs.
Anybody who has a great idea for recycling this material would be welcome in the marketplace.