High-volume, high-value usage of flue gas desulfurization (FGD) by- products in underground mines: Phase 1, Laboratory investigations. Quarterly report, April--June 1995

The kinetics study which is investigating hydration reactions of the ADM by-product (Subtask 2.2) was continued this quarter. This study further aided in gaining information on mineral precipitation and dissolution reactions during hydration of the ADM materials. The information is of importance for a comprehensive understanding of the factors that control strength and long-term stability during aging of FGD materials. The decision was made by Addington, Inc., DOE, and the University of Kentucky that the originally selected mine site for the emplacement demonstration must be changed, mainly for safety reasons. Mine selection will be a priority for the next quarter (Jul--Sep, 1995). Another activity during this reporting period was related to Subtask 4.3, the selection and testing of the transport system for the FGD material. A laboratory-scale pneumatic emplacement test unit (ETU) for dry FGD materials was built at the CAER to generate data so that a final selection of the field demonstration technology can be made. A dry pneumatic system was chosen for laboratory testing because the equipment and expertise available at the CAER matched this sort of technology best. While the design of the laboratory system was based on shotcrete technology, the physical properties of the emplaced FGD material is expected to be similar for other transport techniques, either pneumatic or hydraulic. In other words, the selection of a dry pneumatic transport system for laboratory testing does not necessarily imply that a scaled-up version will be used for the field demonstration. The ETU is a convenient means of producing samples for subsequent chemical and physical testing by a representative emplacement technology. Ultimately, the field demonstration technology will be chosen based on the laboratory data and the suitability of locally available equipment