Identification and impact assessment of parameters on open stoping in the Kylylahti mine

The stoping performance has a paramount effect on the economic viability of underground mining operations. Increasing volumes of overbreak diminish the ore quality and impose additional hauling expenditures. In contrast, any form of valuable material left inside the stope reduces the operational profit immediately. Knowing the parameters which affect stoping positively or negatively is of great interest to any mine planning engineer, as it allows more predictive and accurate production numbers. This study is devoted to identifying important parameters to affect longhole open stoping in the Kylylahti mine. The introduction to stope planning is done by means of a comprehensive literature review on different dilution quantification and stope design methods. A further theoretical part of this study describes well-researched factors that are considered to have a solitary impact on generated stope overbreak and ore loss. Besides the importance of geological information on rock mass and formations, the accuracy of proper stope design as well as drilling and blasting pattern govern the success in stope efficiency. The examination of the stope data revealed several parameters that steer the stope efficiency. Few parameters such as stope dimensioning tend to affect longitudinal and transverse stoping likewise. Main focus here is put on the correlation of varying stope sizes and associated overbreak. The inclination of stope walls is also found to affect both stoping methods accordingly. Visual and numerical observations showed strong sensitivity of stoping towards structural formations such as foliation in the Gap zone or in the lower Wombat orebody. The mining sequence is a parameter that mainly governs the distribution of ore overbreak and ore loss in longitudinal stopes. Dependencies on the stope locations with associated overbreak correspond to transverse stopes only. A compelling new insight is demonstrated that states the correlation of ore overbreak in primary stopes and the ore loss in secondary stopes. Conclusively, different methods are documented that provoke or prevent excessive overbreak and ore loss. The study concludes with suggestions on how to improve stoping based on the results of the stoping parameter identification