Noninvasive Weight Determination of In-Place Ore Stockpiles at Six Defense Depots

摘要

The Defense National Stockpile Center (DNSC) maintains stockpiles of high-grade ores at numerous installation locations throughout the country and has a requirement to produce current weight estimates for selected piles as part of a national audit The ore piles for this study are located at the Hammond Depot Indiana; New Haven Depot Indiana; Warren Depot Ohio; Curtis Bay Depot Maryland; Point Pleasant Depot West Virginia; and Anniston Army Depot Alabama. Microgravity measurements were performed over selected ore piles to provide high-resolution surveys of the gravitational field from which the average bulk density of the ore material was determined Parasnis' method was used to analyze the gravity anomaly data. Ore pile volumes were determined using standard land surveying methods. The computed weights for each ore stockpile are compared to the DNSC reported weights and differences should be within 10 to 15 percent Results of this investigation indicated that the computed weights 42 of the 82 piles surveyed are below or within the expected percent difference error range. Thirty-three ore piles have differences ranging from 15 to 25 percent and seven stockpiles had differences greater than 25 percent of the reported values. The greatest differences were computed over piles in which settlement of the ore material below the ground surface had taken place, site conditions were such that definition of the true pile base was poor, or pile documentation and reported weights are in error.