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Narrow Vein Stope Design

Narrow Vein Stope Design. Penny Stewart PhD BEng(Mining). Evaluate Previous Methods. Empirical Stability graphs Industry standard. Developed from 100’s of large open stoping case studies with few narrow-vein case studies in database. ~ 80% accurate when applied to large open stopes.

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Narrow Vein Stope Design

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  1. Narrow Vein Stope Design Penny Stewart PhD BEng(Mining)

  2. Evaluate Previous Methods • Empirical Stability graphs • Industry standard. • Developed from 100’s of large open stoping case studies with few narrow-vein case studies in database. • ~ 80% accurate when applied to large open stopes. • Stopes designed using stability graphs would expect between 5-10% dilution. Extended Mathews Stability Graph, after Mawdesley and Trueman, 2000

  3. These parameters were shown to significantly affect narrow-vein dilution Adjustments for each of these effects Applicability to Narrow-vein • 677 relatively narrow case studies from Barkers mine (WA), Callinan mine (Canada) and Trout Lake mine (Canada) showed poor correlation to existing stability graphs. • Application of existing stability graphs to narrow-vein is problematic because they do not take into account: • Relaxation • Blasting parameters • Stress damage • Backfill abutments

  4. Stress Relaxation Study • Hypothesis: Due to their tabular geometry, narrow-vein stopes are particularly susceptible to relaxation. • Literature on effect of stress relaxation was conflicting and contradictory. • Theorised that different types of stress relaxation behave differently. 3 types defined: • Partial relaxation • Tangential relaxation • Full relaxation • Empirical study 55 case studies using Map3d • Results – Full and tangential relaxation required adjustments • - 30% reduction in stability number, N.

  5. Stress Damage Study • Hypothesis: Stress damage contributes to narrow-vein dilution. • Stope walls exposed to high stress.

  6. Results of Stress Damage Study • Of 410 case studies modelled over 36 months of mine life, only 10 incurred stress damage related dilution. • Stress damaged stopes had 0.27 m more overbreak than non-stress damaged stopes (94% confidence level) • 0.27 m overbreak = 34% dilution

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