Avaliação de reservas por métodos convencionais: um estudo de caso na Mina de Canoas 2 (PR)

Abstract

This paper presents the results of a study carried out on exploration data from Canoas Deposit in order to compute the geological reserves of Pb, Zn, and Ag. This deposit is located in the Municipality of Adrianopolis, State of Parana, southern Brazil, and was exploited by Plumbum Mining and Metallurgy Co. until 1995. The basic data considered in this paper come from diamond core drillings made at the nodes of a rhombic grid with a spacing of 50 meters. The mineralized zones were recognized and their grades were determined. These basic data were analyzed statistically in order to determine the statistical parameters of population distributions of Pb, Zn, and Ag. Later, the same data were averaged for the mineralized zone, and the same statistical analysis was made. The results show that the averaged samples produced a more symmetrical distribution close to a normal distribution for the mineralized zone. The data prepared in this way were used to compute the geological reserves by conventional methods, such as: standard section, linear section, triangles, and polygons. The diverse conventional methods applied in this study did not present significant differences in ore reserves or average grades. This similarity in the results is due to the type of deposit (stratiform) analyzed, and to the regularity in its thickness, grade distribution and sampling grid. This suggests that for similar deposits any of the conventional methods should give a reliable estimation of ore reserves.