JUSTIFICATION OF MARGINAL CONTOURS OF OPEN DEVELOPMENT OF STEEPLY SLOPING VEINS AND VEIN ZONES

Abstract

The open-pit mining boundary limits were justified for a gold-polymetallic deposit consisting of steeply dipping veins and vein and ore zones. Deposit production began primarily in 2008. Mining was interrupted in 2016–2020 and 2023–2024, and continued on a very small scale in 2021–2022. The deposit is currently not in production.

To solve this problem, an analysis of the geological and technical conditions of the gold-polymetallic deposit, consisting of veins and vein and ore zones, was first conducted. A methodological framework for solving the problem is then presented, according to which the open-pit mine boundary limits are justified based on the condition of equality of the boundary and boundary stripping ratios. A formula for determining the boundary stripping ratio is derived, based on the condition of equality of profits obtained from open-pit and underground mining. Well-known formulas for determining the stripping ratio for the deposit under consideration are presented. Industrial vein outlines in sampling plans were drawn primarily along geological boundaries, while vein and ore zones were delineated using cutoff grades. Ore reserves were delineated using vertical projections of ore bodies. After reserve delineation, ore body cross-sections were constructed along seven exploration profiles. The average stripping ratio for the cross-sections was calculated. To determine the boundary stripping ratio, the deposit's development indicators were calculated. By comparing the calculated values ​​of the stripping ratio and the boundary stripping ratio, the boundary between open-pit and underground mining was selected - the lower boundary of open-pit mining for a gold-polymetallic deposit consisting of veins, veins, and ore zones.