Loop pumping tests of crushed rock mixed with thickened tailings
Bibliographic record
Abstract
LKAB operates three mines in northern Sweden, where the climate is subarctic with an average temperature of about 0oC. LKAB’s long-term overall objective includes feasibility considerations of thickened or filtered tailings combined with waste rock co-disposal covering cyclic economy considerations and landscape forming. At the Kiruna underground mine, about 3.5 Mtonnes of tailings and 12 Mtonnes of waste rock are generated annually. Crushing to less than 30 mm is part of the sorting plant processing, and the rock is deposited in stockpiles while the tailings are pumped conventionally to water-holding impoundments. The aim is to indicatively test the pipeline pumping of paste-rock mixtures at solids concentrations by weight of over 85% to limit segregation and leakage during deposition in nearby old pit holes. A test was carried out at a paste thickener with direct access to fresh paste, which was mixed in a concrete mixer with crushed rock from the processing. A 38 m long loop with a pipeline inner diameter of 0.075 m was equipped with a concrete type of pump. Unfortunately, a second test in a larger pipe could not be carried out at the planned time. LKAB then had the opportunity to test a laboratory-scale concrete industry device, the sliding pipe rheometer, Sliper, developed to simulate concrete pipeline pumping frictional resistance in a 0.126 m diameter pipeline. Initial loop results with crushed rock particles of up to 10 mm with a rock-to-paste mass ratio R:P of 1.2:1 showed a pressure requirement of about 25 kPa/m at 0.7 m/s for a total solids content of 84% by weight corresponding to 65% by volume and a water content of 19% (Solids density 3000 kg/m3). The 10 mm product loop pressure results agreed relatively well with simulated Sliper data scaled to 0.075m from 0.126 m for Cw 85-86% and R:P of up to 2.6:1 at 0.7 m/s. The 30mm Sliper result at 89% indicated a pressure requirement of 14 to 24 kPa/m at 0.7 m/s for R:P of 2.6:1 and 3.5:1, respectively. With a 0.15 m diameter pipeline, a pumping requirement of 20 kPa/m at 84% and 0.7 m/s was also discussed regarding feeding requirements. The results form the basis for a planned larger-diameter test. Long-term flexibility factors related to tailings availability and clarification of suitable routings and allowed water contents may necessitate that the wider diameter loop test includes a limited once-through pipeline pumping demonstration feeding arrangements. Variations in the rock-to-tailings ratio related to tailings availability and disturbances can be investigated. The system feasibility for filling depressions may cover a concentration span starting from about 75% by weight which means a more stratified flow where the coarsest particles form a sliding bed.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".