1972 Table 48 – Pattern Expansion Sensitive Analysis Bulk Explosive Pattern Increase (%) P80 Variation (%) Effective Energy (MJ/t) Ore Waste Standard Baseline - 0.66 0.48 High Energy 0.0% -9.3% 0.73 0.54 6.0% -4.9% 0.69 0.50 10.0% -2.8% 0.67 0.48 13.0% -1.2% 0.65 0.47 17.0% 2.2% 0.63 0.46 3.3 Ore Dilution Control Using Blast Movement Modeling 3.3.1 Context and Objectives Santa Luz’s orebody has strong structural control with economically viable domains differentiated by total organic carbon (TOC): dacitic material (TOC < 0.5) and carbonaceous material (TOC > 0.5). Carbonaceous material is associated with preg‑robbing—a phenomenon in which naturally occurring organic carbon (and some clay minerals) adsorb the dissolved gold cyanide complex from slurry, pulling gold out of solution and thereby reducing recovery. In the resin‑in‑leach (RIL) process, ion‑exchange resins are mixed with the slurry to adsorb the gold cyanide complex directly in the leach tanks; when preg‑robbing is present, the carbonaceous matter competes with the resin for the gold complex, lowering resin loading and increasing losses unless the blend is controlled. In practice, post‑blast mixing between these domains was increasing dilution and driving variability in plant feed. Site tracking in the second half of 2023 recorded 18.4% dilution, above the 15% target. The project’s objective was to reduce dilution and stabilize blend quality by mining the post‑blast reality rather than in‑situ polygons, aligning dig boundaries with TOC‑based domains to improve the reliability of grade sent to the crusher. 3.3.2 Design and Implementation To reach the objective of reducing dilution and stabilizing blend quality, the site implemented a three‑dimensional blast movement modeling workflow using OREPro™ 3D. The workflow transformed the in‑situ grade‑control model into a post‑blast model and issued optimized dig‑layers that reflect actual material displacement after blasting. Ahead of modeling, mineralized lithologies were classified by total organic carbon (TOC)—for example, dacite (TOC < 0.5) and carbonaceous (TOC > 0.5)—so the optimized post‑blast polygons directly supported blending decisions in the plant. OREPro™ 3D was prepared with site data and blast designs to simulate movement across the blasted volume; the resulting post‑blast model provided geologists with greater confidence in the composition of dig‑layer polygons and the ore/waste delineation during excavation. Operationally, mining proceeded against the modeled post‑blast dig‑layers rather than in‑situ boundaries, aligning shovel instructions with the TOC‑based classification. This practice targeted lower dilution and more reliable blends to the crusher, integrating seamlessly with Santa Luz’s existing grade‑control and reconciliation routines.
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