Interval logging in blast holes for 3D geological modeling of blasting blocks at Lebedinsky GOK

Abstract

The current practice of geophysical logging in blast holes at Lebedinsky GOK reduces to evaluation of an average content of magnetic iron per test bench. In the meanwhile, the measurement procedure in use (magnetic susceptibility logging) allows obtaining more comprehensive data from each blast hole as the measurement frequency is every 10 cm. Interpretation of geological structure of blasting blocks uses 2D models (or a charts). These methods are incapable to detect in full ore and barren rock interfaces, to locate ‘blind’ diorite dykes and to pattern qualities within process grades. The authors have developed a batch processing procedure for well logging data in Surpac environment. In this case, 3D interpretation of geological structure of an extraction block is implemented using the interval logging data on magnetic susceptibility in blast holes. The implemented analysis shows that geophysical logging fails to identify some thin dykes, or identifies them unreliably. The current logging practice, when geological interpretation has only one averaged value per hole, is incapable to ensure sufficient accuracy of interpretation of geological boundaries inside blasting blocks. For more particular conclusions, the research procedure needs further study and refinement. The use of the proposed procedure for geophysical logging data can accelerate processing of geophysical test data from blast holes, improve accuracy of interpretation of geological boundaries, correlate the data with specification of geological structure of blocks and reduce loss and dilution in the long run.