DEM simulation and analysis of operating parameters on grinding performance of a vertical stirred media mill
Bibliographic record
Abstract
Stirred media mills have been increasingly used in ultra-fine grinding. The VXPmill is a vertical high speed stirred media mill for grinding mineral ores with high efficiency. Since it is a new technology in the industry, there is little understanding on the breakage kinetics of the mill. In order to gain more knowledge about the VXPmill, computer modelling of the mill was performed. Laboratory grinding trials were also conducted on a pilot scale mill to provide more information about the mill’s capability, as well as verify simulation results. DEM (Discrete Element Method) is a powerful tool in predicting particle behaviour, which is ideal for the study of stirred media milling. The CFD (Computational Fluid Dynamics) is used to model the motion of slurry by numerically solving the Navier–Stokes equations facilitated with the Volume of Fluid (VOF) and multiphase flow models. Simulation results suggested that a velocity gradient exists in the fluid field and grinding media in the mill. The highest grinding media velocity was reached near the disc edge in the horizontal direction and near the bottom of the mill in vertical direction. Those are the most active grinding zones in a vertical stirred mill. Different operating parameters such as stirrer rotational speed, slurry solid content and slurry viscosity have an influence on mill performance. Simulation results show that operating the mill at a high impeller speed helps to improve mineral liberation, while at too high impeller speed leads to a waste of electric energy without much improvement in mineral liberation. As well, a mid-level slurry solid content (15% v/v to 30% v/v) was found to achieve the best energy utilization during grinding. The slurry viscosity should be kept low to minimize the effect of high shear stress in the slurry. The influence of various operating parameters can be combined into the ‘stress intensity’ which describes the capability of a stirred media mill. Operating parameters also have an influence on the magnitude of force magnitude between grinding media which will result in different breakage mechanism. Fracture breakage mechanism plays a more important role than attrition in VXPmill.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| 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 | 0.001 | 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".