How it works
Screening separates particles by whether they can pass an aperture. Material is presented to a screening surface; particles smaller than the opening have a chance to pass to the undersize (fine) stream, while larger ones are retained as oversize (coarse). The chance of passing is not a clean step at the mesh size — it depends on how often a particle meets an aperture, its orientation, and near-mesh particles that only just fit.
The result is a smooth grade efficiency (partition) curve: the fraction of each size class that reports to the coarse stream. Two numbers summarize it — the cut size (where half the material goes each way) and the sharpness (how steeply the curve rises around the cut). High sharpness means a clean separation; low sharpness leaves near-size material in the wrong fraction.
Real screens lose sharpness to blinding, overloading, and cohesive or moist material. At the population level the unit conserves total solid mass and simply redistributes each size class between the two product streams.
The model
DyssolPro splits the feed with a grade efficiency G(x) — the mass fraction of each size class that leaves in the coarse stream, with the fine stream taking the remainder. Four curve models are available; total mass is conserved and the split is set entirely by the chosen curve and its parameters.
- Plitt — A widely used exponential partition curve defined by a cut size and a sharpness parameter α.
- Molerus & Hoffmann — A partition curve with cut size and sharpness, derived from a stochastic separation model.
- Probability — A normal-distribution-based curve defined by a mean and standard deviation.
- Teipel / Hennig — A flexible curve with two sharpness parameters and a separation offset.
Equipment this model can represent
Any screening duty where a size cut splits the feed into oversize and undersize.
Vibrating / shaker screens
Inclined or horizontal decks vibrated to stratify and transport material across the mesh.
Tumbler / gyratory screens
Gentle gyratory motion for fine, accurate classification.
Trommel (drum) screens
A rotating cylindrical screen for robust scalping and washing duty.
Ultrasonic-assisted fine screens
High-frequency excitation of the mesh to keep fine, cohesive powders from blinding.
Typical engineering studies
What teams investigate with the screen model.
Cut and split prediction
Predict the oversize/undersize split and both product PSDs for a given cut size and sharpness.
Closed mill–screen circuit
Return oversize to a crusher and study recycle load and product PSD across the loop.
Cut & sharpness sensitivity
Map how cut size and sharpness move misplacement and yield.
Partition-curve fitting
Fit a model (Plitt, Teipel/Hennig, …) to a measured partition curve, then use it predictively.
Cut optimization
Optimize the cut to balance product quality against recovery across the connected process.
Technical FAQ
How do I choose the right screen mesh size?
As a starting point the mesh roughly equals the target cut size, then you adjust for sharpness and near-size load. In DyssolPro you set the cut size in the screen model, predict the resulting split and both PSDs, and iterate the cut to meet the product spec before committing to a mesh.
Why is my vibrating screen blinding?
Blinding happens when near-size or sticky particles lodge in the apertures, often worsened by moisture. DyssolPro doesn’t model blinding mechanically, but you can represent its effect as a reduced effective sharpness and study how the degraded cut changes the product — the mechanical fix (vibration, ultrasonics) stays equipment-side.
How can I improve screening efficiency?
Efficiency comes from a sharp cut plus enough screening area and residence time. In DyssolPro you tune the sharpness parameter and cut size to see how misplacement responds, and study the screen inside its circuit so the fix accounts for recycle.
What causes too much good product in the oversize fraction?
Either the cut is too coarse or the sharpness is too low, so undersize is retained. DyssolPro lets you lower the cut size or raise the sharpness in the model and quantify exactly how much good product you recover.
How does moisture content affect screening performance?
Moisture makes fines cohere and blind the mesh, blunting the cut. DyssolPro has no moisture calculation, but you can model the upstream drying in the flowsheet to find a safe moisture window and represent the residual effect through a lower effective sharpness.
How do vibration frequency and amplitude affect separation?
They control stratification and transport across the deck — a mechanical effect outside the model. Their net result on the cut is captured in DyssolPro through the calibrated cut size and sharpness fitted to the screen’s measured performance.
How can I reduce screen wear when processing abrasive particles?
Wear is mitigated with mesh material and coatings — an equipment choice DyssolPro doesn’t model. The simulator covers the process side: the size split and the load it sends downstream, so the rest of the line is designed correctly around the screen.
What is the difference between scalping, classification, and dedusting screens?
Scalping removes a small coarse fraction, classification splits the feed at a defined cut, and dedusting removes fines — all three are a grade-efficiency split at a different cut. In DyssolPro you represent each simply by setting the cut size and sharpness accordingly.
How do I size a screen for a powder processing line?
Mechanical sizing needs the required area and capacity, which is a separate calculation. DyssolPro gives you the piece sizing depends on — the size split and the mass loads to downstream units — so you can size the deck against a known duty.
How can I model screen separation efficiency?
That is the core of the unit: choose a grade-efficiency model (Plitt, Molerus & Hoffmann, Probability, or Teipel/Hennig), set its cut and sharpness, and DyssolPro returns the size-resolved split and both product PSDs.
How can I prevent screen clogging with sticky powders?
Stickiness and cohesion drive clogging, addressed by deck design, ultrasonics, or conditioning. DyssolPro models the separation, not the clogging, but you can study upstream drying/handling in the flowsheet to reduce the cohesion that causes it.
Why is screen throughput lower than expected?
Usually blinding, overloading, or moisture is shrinking the effective open area. DyssolPro doesn’t compute capacity loss directly, but you can study how a degraded cut and sharpness, or a different feed split, change the product — and flag whether the cause is process or mechanical.
How does particle shape affect screening accuracy?
Elongated or flaky particles pass or retain differently than their nominal size suggests, spreading the cut. The model uses size rather than shape, so in DyssolPro this is absorbed into a calibrated sharpness fitted to real data.
How can I reduce fines in the oversize stream?
Sharpen the cut and ensure adequate screening so fines have a chance to pass. In DyssolPro you raise the sharpness parameter and study the fines-in-oversize fraction against the cut to find the right setting.
How do I optimize screen inclination angle?
Inclination sets material velocity and residence time on the deck — a mechanical variable the model doesn’t resolve. Its net effect on the cut is captured through the calibrated model parameters fitted to the screen’s behavior.
What causes product loss through the undersize stream?
The cut is too fine or the sharpness too low, sending coarse product to undersize. DyssolPro lets you raise the cut or sharpen it and quantify the recovered product directly from the partition curve.
How can I select between ultrasonic and mechanical screen cleaning?
Both are anti-blinding methods — an equipment decision outside the simulator. DyssolPro’s contribution is the process side: predicting the split you should achieve once blinding is controlled, so cleaning is sized to maintain it.
How do I improve screening of cohesive powders?
Cohesive powders need anti-blinding measures and often drier feed. DyssolPro can model the upstream conditioning in the flowsheet and represent the residual sharpness loss, so you can judge what cut is realistically achievable.
How can I measure screening efficiency in production?
You sample the oversize and undersize and build a partition curve. DyssolPro then calibrates a screen model to that curve, turning the measurement into a validated unit you can use predictively.
How can I model screen performance using partition curves?
The grade-efficiency curve in the screen models is exactly a partition curve. In DyssolPro you fit the Plitt or Teipel/Hennig parameters to your measured partition curve and the unit reproduces that performance inside the flowsheet.