Mining Publication: Pillar Design and Strategies for Retreat Mining

One of the keys to miner safety and an efficient recovery of the reserves is to design sufficiently sized production pillars that will prevent pillar squeezes, excessive pillar spalling, severe floor heave, roof falls, and pillar bumps. Currently, few mine operators design sections that will be retreat mined using empirical formulas or numerical models that estimate abutment pressures generated by adjacent mined-out workings. The U.S. Bureau of Mines is in the process of field testing and refining a "user friendly" computer program called Analysis of Retreat Mining Pillar Stability (ARMPS) to estimate abutment pressures developed during pillaring. Analyses of 68 pillar design case histories using the ARMPS program indicate that it can be successfully employed to predict pillar line stability during retreat mining operations.