BAUXSOL AND MGO ADHESION TO PYRITIC ROCKS AT I-99 SKYTOP CONSTRUCTION SITE

The I-99 highway construction debacle, Centre County, PA, has led to the development of significant acid drainage effecting surface runoff, nearby domestic wells, and tributaries to Buffalo Run. One possible remediation strategy for the I-99 site at Skytop is to induce the formation of protective coatings of iron oxide minerals around the pyritic rock. To this end, two slurries were tested with the pyritic rocks in batch experiments. One is Bauxsol (the remnants of bauxite-rich soil after the removal of aluminum; major components are hematite, gibbsite and clay minerals), the other is MgO slurry, which is composed of 65% MgO, 30% lime, and 5% kaolinite. To determine the viability of the approach, rock samples which had been in the batch reactors for two weeks were examined using Environmental Scanning Electron Microscopy (ESEM), Electron Microprobe, and X-ray Diffraction (XRD). Although the hand samples of MgO slurry showed a visible rust formation, the microscopic results showed that no phase transformation had occurred in the study samples. ESEM images indicated a possible reaction zone in the Bauxsol slurry. In addition, hand samples, thin sections, and ESEM micrographs showed that both Bauxsol and the MgO slurries adhere to the surface of pyritic rocks.