Comparison of the Triangular, Polygonal, and a Statistical Method of Computing Grade and Tonnage of Ore for the Silver Bell Oxide Porphyry Copper Deposit.
NTIS: PB 190 033 :33 pages
This report describes a comparison of methods for computing grade and tonnage of ore, leach, and waste material for a mined-out portion of the silver bell oxide porphyry copper deposit; computed values are compared with the actual tonnage of these classes of material produced during mining operations. Comparisons with production records have been made by using both exploration drill- hole assays and development blast-hole assays. The polygonal method is the most accurate for this deposit because it more closely represents the lateral mineral distribution in the deposit. This is demonstrated by plots of the total-copper assay distributions of the development blast-hole assays for a specific bench. The investigation also shows that the smaller vertical assay interval (based on a 5-foot vertical churn-drill hole sample) yields a more accurate estimate of both grade and tonnage than the 40-foot composite assay interval (based on the average of eight 5-foot assay values). This can be attributed to the face that selective mining within a bench can separate out much of the waste and leach material that is included as ore in the 40-foot composite assay computations. Work done in cooperation with the Bear Creek Mining Company and under a fellowship agreement with the University of Arizona.
IH; Report of Investigation;
NTIS Accession No.
NTIS: PB 190 033