Microwave drying of minerals : experimental and numerical modeling
Bibliographic record
Abstract
This thesis evaluates the application of microwave systems for mineral drying through laboratory experiments and numerical modeling. Four types of minerals were procured from a mining partner, with moisture contents up to 25%. Their material properties – including thermal conductivity, heat capacity, density, initial moisture content, and dielectric loss factor – were characterized. Drying tests were conducted in a commercial microwave oven, with samples exposed to microwave irradiation to reduce moisture content to below 1%, while ensuring temperature control below a specified threshold. Materials were incrementally heated, with mass loss and surface temperature measured until target mass losses were achieved. Results revealed a two-stage drying regime: a constant-rate period up to a critical moisture content, followed by a falling-rate regime. A numerical replica of the commercial microwave oven was developed, including key components such as three rotating stirrers, a ceramic plate, and three separate magnetrons. Parameters such as air inflow, stirrer rotation speed, microwave generator ramp-up time, and forward power were measured and incorporated into the numerical model. The characterized material properties were integrated into a coupled electromagnetic and heat transfer finite element model implemented in COMSOL Multiphysics to investigate drying rates and temperature profiles. Predicted mass loss and temperature changes under experimental microwave heating conditions were compared with experimental results. Results indicated that microwave energy was predominantly consumed by water evaporation. For the studied material M2, which contained sulfur and required maintaining temperatures below 125 °C, the numerical model was particularly useful in determining internal temperatures that were experimentally inaccessible. The model predicted maximum material temperatures well below 100 °C during 60 s microwave exposures, sustaining an average drying rate of 2 g/s. These findings demonstrate that microwave heating offers a highly effective alternative for drying applications in mining, particularly where temperature sensitivity is a key operational requirement.
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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 | 0.001 |
| 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 | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".