OFFICIAL A slot/initial opening is created (e.g., boxhole or start slot), then longhole production drilling and blasting proceed. Mined stopes are subsequently backfilled to provide support and enable adjacent stopes to be extracted safely. Planning architecture is hierarchical: ● Stopes are grouped into blocks (10 neighboring stopes at the same stope level). ● Barrier pillars separate blocks to maintain regional stability and host main access drifts. ● A stope level comprises 12 blocks. ● Five stope levels stacked form a mining field. ● Mining fields are separated by a sill pillar to decouple interactions between stacked levels. Figure 2 – Horizontal and vertical sections of one mining field, including drift positions (red). 5.2 Stope geometry options and key planning metrics A scoping layout was evaluated for two stope lengths while keeping width and height constant: ● Stope geometry (base case): 20 m (width) × 30 m (height) × 50 m (length) ● Optimized geometry: same width/height, 80 m length (subject to verification) Barrier pillars are substantial (e.g., 25 m × 200 m and 50 m × 425 m) and materially affect extraction ratio. In the base case, the extraction ratio is ~46% per stope level; with 80 m stopes it improves to ~53%. Longer stopes also improve the development-to-ore relationship, reducing meters of development per 1,000 t produced. Table 1 gives a comparison between characteristic values and parameters for the two stoping layouts under consideration.
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