Unplanned dilution directly adds cost to production from mining, milling, tailings disposal and administration. Additionally, unplanned dilution decreases the productivity, profitability and may affect the planned life of mine. Identifying and quantifying the potential for the unplanned dilution allows optimization of the mining plan and mining practices to minimize the adverse impact on productivity and the cost of production.
The dilution Rating System (DRS) has been developed to more accurately predict dilution thickness and the variable potential for dilution, from individual stopes to life of mine planning.
The DRS utilizes the methodology developed for the Mining Rock Mass Model (Seymour et al 2007, Jenkins et al 2009) to generate a three-dimensional dilution rating model, which is then calibrated against stoping performance. Dilution can be predicted more accurately and the parameters affecting dilution can be determined and minimized through improved mining techniques, for example blasting and ground support design. Potential high dilution areas can be identified in the planning stages of the mine and systems put in place to mitigate the risk of excessive dilution.
This paper presents the methodology used to develop the DRS and then successfully predict the dilution for both the hanging wall and the footwall of stopes at the Gara Gold Mine. This has enables the expected dilution to be more accurately predicted and mitigated where possible this reducing unplanned dilution.
Author: C R W Seymour, C Nyoni, T Nguyen and G D Dempers
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