Горные науки и технологии (Jun 2018)
Determination of ore intervals when estimating reserves using Micromine Software
Abstract
In domestic practice of ore reserve estimation, including at the stage of Feasibility Study of conditions, ore intervals (composites) are determined taking into account the conditions. The conditions (Resource Estimation Parameters) include: cut-off grade (CoG) of a useful component; minimum thickness of ore body (minT); maximum allowable thickness of waste rock or substandard ore interlayers (maxTS), included in the ore body outline; minimum GT, calculated as the product of the cut-off grade by the minimum thickness of the ore body. Recently, in practice of ore reserve estimation, options for automating this process began to appear in specialized programs for processing geological and survey information. The main subject for developing automation for the process of creating ore intervals in the Micromine software and the topic of this paper is determining an ore body boundaries in the direction of thickness using the conditions. The situation under consideration arises in the absence of external geological boundaries and is typical for ore bodies of various morphologies: mineralized dykes, mineralized zones, stockworks, skarns, ore shoots, etc. Earlier, prior to the study of this problem, the composite calculations were implemented in the Micromine software for the following scenarios: along boreholes, by benches, by intervals, by geology, by grade. The software developers, starting from version 16, decided to implement the algorithm for calculating ore intervals based on the conditions as an independent method in a separate tab of the menu "Boreholes/Composite calculation/By grade (GKZ)". The main varieties (parameters) of the algorithm for building of ore intervals include: Less Stringent Rules and Strict Rules. General provisions for considering ordinary ore intervals, the similarities and differences in the operation of the main varieties (parameters) of the algorithm are given. Formally, for calculating ore intervals based on the conditions, it is necessary to apply the algorithm that takes into account all the conditions as fully as possible. In Micromine software, this algorithm consists in applying the Strict Rules with the “Deny adjacent ore intervals” option enabled. In practice, multivariance of "tie" and delineation of ore bodies based on the identified ore intervals takes place. The paper provides several formalized examples explaining the legitimacy of using one or another method for identifying ore intervals. Automation of the process of determining ore intervals leads to significant increase in the speed of data processing. The described algorithms allow for, subject to properly prepared and verified data available, to rapidly calculate and statistically process numerous options for obtaining ore intervals based on the input variable data of conditions: CoG, minT, maxTS, maxGT.
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