The grade distribution within the Quebradona shows that there is high grade in the upper portion of the orebody and the grade reduces with depth. Sub-level caving (SLC) is a top-down mining method which makes it a sensible and robust option for the initial mining phase of the operation offering the following advantages:
• Less upfront capital compared to other caving methods;
• Ability to access high grade ore located at the top of the orebody during the early stages of the production schedule;
• Early establishment of the surface subsidence (the undercut is shallow compared to block caving methods);
• A footprint capable of production rates >5Mtpa, thus allowing a rapid payback period;
• Provides flexibility through drill and blast techniques to define the ore boundary on each production level;
• Flexibility to change the mining method to other caving methods, if required.
SLC is a common caving method and was chosen to maximise the best Mineral Resource extraction that is aligned with the TSF capacity of 119Mt.
Geotechnical modelling used 3D models for the structure, lithology and alteration and these built using the implicit modelling workflow in Leapfrog™ Geo software.
An external assessment on caveability demonstrated that the current mining geometry and dimensions is suitable for caving with the block height: block width ratio being less than 2:1, giving a high-level of confidence of cave connection to surfa ........
