Leaching kinetics of tungsten in scheelite tailings in sodium carbonate solutions at low temperatures (25–75°C)
Bibliographic record
Abstract
The leaching kinetics of tungsten in scheelite tailings in sodium carbonate solutions at low temperatures (25–75°C) were found to closely follow the predicted values based on the shrinking core model (SCM), originally developed at elevated temperatures (150–190°C). Temperature demonstrated a profound positive effect on the leaching kinetics of scheelite. The apparent rate constants, k values, determined from leaching the scheelite tailings at low temperatures, were found to be a few orders of magnitude lower than those obtained at elevated temperatures (i.e. ∼ 10−7 vs. 10−4 s−1). The time required to extract over 90% of tungsten was estimated to be 15 days at 75°C, in contrast to 2 h at 200°C. The experimental kinetic data from leaching the scheelite tailings were found to consistently outperform the kinetic model prediction, by as much as 70% and 400% at 50 and 25°C, respectively. As observed at elevated temperatures, an increase in sodium carbonate concentration or agitation speed had little effect on the leaching kinetics at low temperatures. This study demonstrated the potential use of sodium carbonate solutions as a non-aggressive lixiviant in a percolation or dump leach operation, which could be considered as an environmentally viable reprocessing option for scheelite tailings.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| 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) | 0.001 | 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".