Minimizing dilution in open stope mining with a focus on stope design and narrow vein longhole blasting
Bibliographic record
Abstract
This thesis presents the results of three years of research which focused on minimizing dilution in open stope mining. The research encompassed both stope design and narrow vein longhole blasting. A new empirical design approach has been developed for estimating unplanned dilution from open stope hangingwalls and footwalls. The resulting design charts are based on quantifiable measurements of overbreak/slough made with the Cavity Monitoring System (CMS), and were developed from a comprehensive database o f stoping histories compiled from six (6) Canadian underground open stoping operations. A new parameter termed ELOS (equivalent linear overbreak/slough) has been introduced and incorporated into the design charts as a measure of unplanned dilution. Theoretical justification for the design methodology has been demonstrated through a numerical modelling study examining the zone of relaxation around open stopes. Statistical methods, neural networks, and additional case histories have been used to validate the proposed design zones. This new approach to stope design is an improvement over existing methods in that it allows stope sizes to be determined based on an "acceptable" level of dilution rather than qualitative descriptions of stability such as: "stable"; "transition zone"; or "potentially unstable". In narrow vein open stope mining, even i f stopes are sized to be inherently stable (i.e. good stope design), blast induced overbreak can result in high levels of unplanned dilution. This study assessed the performance of three narrow vein blast patterns: the 3:2 pattern; the 2:1 (dice-five) pattern; and the 1:1 (stagger) pattern. The study was carried out at the Lupin Mine (NWT). The patterns were evaluated on the basis of: cost; blast damage potential; charge interaction; fragmentation; and tolerance to lapses in quality of drilling and loading practice. Guidelines have been developed regarding the choice and implementation o f narrow vein patterns.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.006 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".