Kinetic investigation of rare earth leaching on Labrador Canada rare earth ore in acidic sulphate medium
Bibliographic record
Abstract
The kinetics of sulphuric acid leaching of rare earth elements in a sample from the Foxtrot deposit in Labrador, Canada was investigated. The selected parameters were, particle size fraction of +38 –53 µm, +53 -75 µm, +75 -106 µm, and +106 -150 µm, sulphuric acid concentration of 0.5 M, 1.5 M and 3 M, temperature of 30, 60, and 90 ℃. The highest extraction efficiency for Ce, Nd and Y was 96.72％, 84.91％ and 72.83％, respectively at the highest temperature, highest sulphuric acid concentration and smallest particle size fraction. The highest selectivity was achieved at +106 -150 μm, temperature of 90 ℃, and sulphuric acid concentration of 0.5 M. It was determined that the kinetic experimental data followed the Jander product layer diffusion kinetic model, a type of shrinking core model, for all three elements. The activation energies for Ce, Nd, and Y were found to be 56.19 kJ/mol, 57.09 kJ/mol, and 38.57 kJ/mol, respectively. After identifying the most suitable kinetic model and calculating the activation energies, the rate orders were calculated for the mathematical model. These values were used to develop semi-empirical mathematical models for each element. The results showed that Y was the least affected by acid concentration and particle size, while Ce and Nd were the most affected. The acid leaching process resulted in crack and porosity formation for certain minerals but no notable change in particle size which is in a good agreement with the Jander kinetic model. The high activation energies with product layer diffusion control suggested that a mixed kinetic model might be in control of the leaching mechanism.
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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) | 0.001 | 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) | 0.001 | 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".