How K-MINE Builds Stopes That Can Actually Be Mined

The Stope as the Core Unit of Mining Optimization

We can now look at how optimization is actually implemented in K-MINE. Our approach starts from a simple idea: in underground mining, the key unit is not a single block – or even a group of blocks – but a stope. A stope already carries orientation, workable dimensions, economic meaning, and alignment with the chosen mining method. So instead of beginning with whichever algorithm happens to run fastest, we start by forming mining clusters that can genuinely be extracted under the site’s geological and technical conditions.

Building a Geometric Framework

The first step is building a geometric framework for the future stope. The block model is grouped into clusters according to the orebody’s strike and dip, and only within the angular limits allowed by the mining method. This matters because underground methods are highly orientation-sensitive. For example, when optimizing a vein deposit for mechanized cut-and-fill, we aim for narrow, vein-parallel stopes with minimal deviation – otherwise both planned and unplanned dilution increase. For sublevel stoping in a massive body, the stope can be larger, and tolerances on orientation are wider. At the same time, minimum and maximum cluster sizes are set: small for narrow veins to capture local swelling; fixed to room dimensions for stratiform bodies so room-and-pillar integration requires no change in discretization.

Defining Optimization Objectives

Once this spatial structure is defined, optimization can begin. In K-MINE, the objective can be based either on quality (grade) or on economics. A grade-driven mode works well for highly variable vein deposits where securing metal content is the priority. The economic mode is often preferred for more homogeneous massive bodies: clusters are evaluated against cut-off, prices, and costs, and only those that provide a positive economic contribution remain in the stope. This avoids carrying marginal volumes that would later need to be trimmed manually.

Applying Geometric and Geotechnical Constraints

After choosing the objective, constraints are applied to the clusters in sequence – this is the heart of the process. We start with geometric constraints: the stope must fit the allowed height range, stay within the maximum width, and avoid shapes that create impractical tapers or bottlenecks. For a gently dipping stratiform deposit laid out as room-and-pillar, spacing, room width, and height are dictated by the method, so the optimizer constructs stopes that follow those exact dimensions. For a stockwork body under sublevel stoping with backfill, constraints reflect the allowable level height and room length so the resulting stope is ready for design without later reshaping.

Next come geotechnical constraints: removing weak zones, limiting spans, and enforcing sidewall stability. If there is a section along dip with unfavorable fracturing, that section is simply marked as inadmissible and excluded, even if the grade is excellent. This is crucial in faulted underground gold mines where rock quality can change dramatically within a few meters.

Economic Evaluation and Stope Refining

Economic constraints are applied only after a cluster passes both geometric and geotechnical checks. Here, the system evaluates whether adding or removing a cluster helps or harms the economics. In veins, this often focuses on dilution control – if an adjacent block brings too little metal but adds too much waste, it is left out. In massive bodies, slight reductions in average grade may be acceptable if they allow for a cleaner, more productive mining shape. In all cases, the decision follows the configured rules that combine geometry, method, and economics.

Refining the stope comes next. K-MINE can adjust sidewalls, modify the stope’s incidence relative to the orebody, and tighten adherence to the valuable zone. The method context matters: for narrow gold veins, adjustments keep mining width minimal and avoid pulling barren rock. For sublevel stoping in massive bodies, refinements smooth edges and remove block-model artifacts, leading to more stable drilling, blasting, and backfilling. The output is a set of stopes already shaped for immediate use in design.

Restricting the Optimization Domain

Another key feature is the ability to restrict the optimization domain. Not every geometric stope is practical at a given stage of development. Some areas may be inaccessible from current levels, located within the influence zone of active stopes, or positioned under protective pillars. In K-MINE, the engineer defines the working volume – the portion of the model where extraction is currently allowed. If optimizing a room-and-pillar section between two ventilation drifts, there is no point in generating stopes outside that window. Similarly, for sublevel stoping above a haulage level, the system can be instructed not to form stopes below a given elevation. This keeps results aligned with real mine constraints.

Throughout the process, the optimizer remains aware of the intended mining method. When tuned for narrow-vein mining, it uses smaller clusters, tight angular limits, and stricter dilution control. For stratiform bodies and room-and-pillar layouts, it aligns stopes with grid-based mine discretization and preserves support pillars. For sublevel stoping in massive orebodies, it emphasizes permissible heights and refined shapes to reduce backfill volume and simplify drilling and blasting. All of this is handled during optimization – not after – so the stopes that move forward are workable, economically justified, and correctly oriented with respect to the orebody.