ECONOMIC ANALYSIS OF UNPLANNED DILUTION IN UNDERGROUND STOPES, case study: Manganez

In underground stopes, unplanned dilution occurs due to the overbreak and slough of walls and roof and consequently contamination of ore with wastes. This phenomenon not only leads to a reduction in the grade and, consequently costing to deficit grade, but also leads to the cost for mining the waste. Hence, the measurement of the amount of overbreak and slough of roof and walls of stopes in order to determine the unplanned dilution and, consequently, the study of the economic effects of it, is very important in underground mining. In this paper, using the cavity monitoring system (CMS), the effects of unplanned dilution on reduction of grade and increase in the cost of mining and reduction in the profit investigated. For this purpose, by defining the linear equivalent of overbreak and slough (ELOS) for the dilution, the system was implemented on 24 stopes of Venarch Manganese Mines and led to the discovery of the relations between the overbreak and dilution parameters and the economic parameters, including prediction relationship of the loss of profit. Results of data analysis indicate that the break-even of over break is in the 2.18 (m) that results 67.38% dilution.