Challenges in multiple sill pillar mining at Vale’s Coleman Mine
Bibliographic record
Abstract
At Vale’s Coleman Mine in Sudbury, Ontario, Canada, multiple diminishing sill pillars exist in the main orebody. The top most sill pillar known as MOB1 (Main Orebody 1), is immediately below a previously mined out area of neighbouring Xstrata’s Fraser Mine and the other two sill pillars MOB2 (Main Orebody 2) and MOB3 (Main Orebody 3) are between two cut and fill (CAF) areas currently being mined at Coleman Mine. All together these sill pillars contain approximately five million tons of ore. An engineered stope sequencing is important for the successful recovery of the sill pillars. As per the current production schedule, there is some overlap in the timing of mining these sill pillars; therefore, mining in one sill pillar will have an influence on the rock mass response in the other sill pillars. As mining progresses, some areas will become stress shadowed, while others will be highly stressed. Managing the changing stress conditions is expected to become increasingly challenging. Recovery of the sill pillars will be executed by longhole/blasthole stoping methods. Maintaining the access to the stopes will be a challenge and will require a sound ground control strategy to deal with changing stress conditions. This paper examines the impact that mining one sill pillar will have on the other sill pillars and proposes tactical geomechanics guidelines to meet the mine production schedule and maximise recovery. The MAP3D boundary element program for numerical stress modelling has been calibrated against field conditions and subsequently used to determine the optimum mining sequence to ensure that these sill pillars can be safely and efficiently recovered. In addition, the development and ground support strategies for the top and bottom sills of the blasthole stopes have also been discussed.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.005 | 0.002 |
| Scholarly communication | 0.003 | 0.001 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".