New Mexico Geological Society Annual Spring Meeting — Abstracts

A mining company in southeastern New Mexico has just completed a prototype pillar recovery operation in the 4th ore zone of the McNutt Potash Member where langbeinite is being mined. The uniqueness of this operation is due to the langbeinite which is too hard and brittle to be extracted using conventional continuous miners so undercut and blast techniques must be used. Although there is a wealth of experience with pillar recovery of sylvite using continuous miners, it is not directly applicable to this operation and a program was established to monitor rock mass behavior during pillar recovery as well as laboratory testing to characterize the engineering properties of langbeinite. A presentation will be made of the monitoring program which incorporated pressure cells, convergence measurements, TDR cables to monitor roof strata movements, air pressure measurements, and a surface survey network. Summary plots of the monitoring data will be presented as well as slides of typical observations made during pillar recovery. At this stage, it has only been possible to make a preliminary assessment of the data so will there not be any attempt to present conclusions and recommendations.