Open Stope Exposure Time and Stope Dilution

CIM Montreal 2003
Mike Yao, Jucheng Wang, Douglas Milne, Gary Allen, Geoff Capes,
Abstract Unplanned open stope hanging wall dilution is a significant cost for many open stope mining operations. Significant advances in empirical and analytical approaches for estimating stope dilution have been made, however, many important factors are still either ignored or assessed in purely subjective terms.

Opening exposure time is a significant factor that influences overall stability and stope dilution. Minimizing stope mucking time has been recognised as a method of significantly reducing stope dilution. Other empirical design techniques based on rock classification attempt to relate opening stability to "stand-up time" or exposure time, however, these approaches have not frequently been applied to the mining industry.

There are many hard to quantify factors that simultaneously influence opening stability and dilution. This creates a significant difficulty for determining the influence of a single variable, such as exposure time, on opening stability. A study is currently being conducted to quantify many of the factors influencing open stope dilution. The assessment of a large comprehensive case history database of Hudson Bay Mine and Smelting Co. Ltd. (HBMS) operations forms the basis of this study.

This paper presents the findings of a study on the influence of stope exposure time on open stope dilution. The study is based on applying existing empirical stope dilution prediction methods to the extensive HBMS data base. Factors assessing the influence of stope hanging wall undercutting, as well as drill and blasting methods have been applied to reduce the scatter in the data base.
Keywords: Rock mechanics, exposure, Stability, Dilution, open stoping
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