How it works
Comminution is the controlled application of mechanical stress until particles fracture. A particle stores elastic strain energy as it is loaded; once the local stress exceeds the material’s strength at a flaw, it breaks into fragments. The energy required scales with the new surface area created, which is why producing fine powder costs far more energy than coarse crushing.
How the stress is applied selects the breakage mechanism: compression cleaves particles into a few large fragments, impact shatters them into many with a broader spread, and attrition chips fines off the surface. Real machines combine these, and the dominant mechanism shapes the product — how much the size is reduced and how broad the distribution.
At the population level the result is a transformation of the whole particle size distribution: coarse classes lose mass and finer classes gain it, under conservation of total solid mass. That population-level view is exactly what a flowsheet simulator tracks.
Selection and breakage functions
Most breakage models describe milling in two steps. A selection function first decides which particles are picked for breakage in a given pass — generally the larger, weaker particles break more readily than fine ones. A breakage function then describes what happens to a selected particle: how its mass is distributed among the smaller size classes it fragments into.
Together they transform the whole particle size distribution — the selection function sets how much of each size class breaks, and the breakage function sets where that broken mass lands. Choosing different selection and breakage functions lets a single model represent very different mills.
Selection function. Sets the probability that a particle of a given size is broken in a pass, capturing how readily each size class fractures.
Breakage function. Sets how a broken particle’s mass is distributed across the finer size classes, capturing the fragment-size spectrum produced.
The model
DyssolPro reduces particle size with one of three selectable crusher models. Each takes the feed particle size distribution and returns the product distribution.
- Bond — An energy-based model derived from Bond’s comminution law, relating the applied grinding energy to the achievable product size.
- Cone — A selective-breakage model tailored to cone crushers, pairing a King selection function with a Vogel breakage function to reshape the full particle size distribution.
- Multi-purpose — A flexible breakage model for a wide range of mills: combine any of seven selection functions with any of four breakage functions to match the comminution behavior of your equipment.
Equipment this model can represent
Any process where applied mechanical stress fractures particles to reduce size.
Jaw crushers
Coarse primary crushing of hard rock by compression between a fixed and a moving jaw.
Cone & gyratory crushers
Secondary and tertiary compression crushing; product top size is set by the close-side setting.
Impact crushers & hammer mills
Breakage by high-speed impact, giving strong size reduction with more fines.
Ball & rod mills
Tumbling grinding media reduce size by impact and attrition for fine wet or dry grinding.
Jet mills
Particle-on-particle impact in a high-velocity gas jet for very fine, contamination-free powder.
Typical engineering studies
What teams investigate with the crusher and mill models.
Product PSD prediction
Predict the product size distribution for a given crusher setting and feed.
Energy & throughput
Relate power input and Bond work index to the achievable x₈₀ through Bond’s law.
Mill–classifier circuits
Couple the crusher with a screen or classifier and study recycle load and circuit performance.
Process-parameter sensitivity
Map how the model parameters and feed PSD move the product size and the fines fraction.
Feed-variability studies
See how changes in feed PSD propagate to the product and downstream units.
Model-based Design of Experiments
Screen experiments in simulation before running them on the plant.
Scale-up & optimization
Fit parameters to lab data, then run the validated unit at production throughput and optimize against targets.
Technical FAQ
How do I reduce particle size in a mill without generating too many fines?
The standard solution is a closed mill–classifier circuit: grind only until particles reach cut size, then recycle the oversize instead of over-grinding the rest. In DyssolPro you build exactly that circuit, calibrate the crusher model to your material, and run an optimization step to find the mill setting and recycle ratio that hit the target size with the fewest fines — before changing anything on the plant.
What causes overheating during milling?
Overheating comes from the share of grinding energy that dissipates as heat rather than fracture, which grows at fine sizes and high specific energy. DyssolPro quantifies that driver: the Bond model gives the specific energy input across operating points, so you can choose a size target and throughput that limit the thermal load, and connect downstream cooling or gas units in the flowsheet to size the duty.
How can I choose the right mill for brittle powder?
Brittle materials fracture readily under impact, so hammer, pin, and jet mills are the usual fit — the choice then turns on target fineness and heat sensitivity. DyssolPro lets you parameterize each candidate duty (work index, target PSD) and compare predicted product distribution and specific energy at your throughput, so the decision rests on numbers rather than vendor rules of thumb.
How do mill speed and grinding media affect particle size?
Higher speed and larger or denser media raise impact energy and push the product finer — up to the point where fines and energy cost climb steeply. These effects map onto the crusher model’s calibrated parameters; once fitted, you vary them in DyssolPro sensitivity studies to see how product PSD and energy respond before re-setting the machine.
How can I reduce energy consumption in grinding?
The biggest lever is not over-grinding: target the coarsest size that still meets spec and close the circuit with a classifier. DyssolPro’s Bond model links power, work index, and throughput to the achieved x₈₀, so you can optimize the size target and circuit configuration for minimum specific energy.
Why is my mill product particle size distribution too broad?
A broad product usually means a wide breakage spectrum with no classification to tighten it. With DyssolPro’s Cone model you study how selection and breakage parameters and the feed PSD set the spread, then add a classifier in the flowsheet and optimize cut size and recycle together to narrow the product.
How do I prevent material buildup inside a crusher?
Build-up is driven by moisture and stickiness, so the fix is usually feed conditioning — drying or controlling moisture upstream. DyssolPro helps you find that window: model the upstream drying and handling in the same flowsheet and identify the feed-moisture range that keeps material flowing freely into the mill.
What is the difference between impact milling and compression milling?
Compression (jaw, cone, roll) cleaves particles into a few coarse fragments at low energy; impact (hammer, jet) shatters them into many fragments — finer, but with more fines and heat. In DyssolPro you represent either route by calibrating the crusher model to the machine’s measured product, then compare the two as flowsheet variants on PSD and energy.
How can I model breakage kinetics in a mill?
Breakage is captured by a selection function (what breaks) and a breakage function (into what) — which is precisely DyssolPro’s Cone model, using King selection and Vogel breakage to transform the full PSD. Calibrate the parameters to your data, or implement a custom law in Model Maker if your material needs one.
How do I scale up milling from lab scale to industrial scale?
Reliable scale-up transfers material functions (work index, selection and breakage parameters) fitted at lab scale, not geometry alone. DyssolPro is built for this: fit the model to lab data, then run the same validated unit at production throughput inside the full flowsheet to confirm product PSD and energy before commissioning.
How do I prevent product contamination during milling?
For sensitive products the route is low-wear equipment — jet mills with no media, or ceramic liners. That material choice sits outside the simulator, but DyssolPro fixes everything around it: it predicts the PSD and stream composition through the circuit so the process is fully designed before you commit to a contamination-critical machine.
Why is my mill throughput decreasing over time?
Declining throughput usually points to wear opening up the gap and liners, or a drift in feed properties. DyssolPro doesn’t track wear, but it isolates the process consequence: change the effective setting or work index and see how product size and recycle load move, which helps you separate a wear problem from a feed problem.
How does feed particle size affect mill performance?
Coarser feed demands more energy and can broaden the product, while too-fine feed under-uses the mill. This is directly in scope — vary the inlet PSD in DyssolPro and the model (Bond via x₈₀,in, Cone across the whole distribution) shows the effect on product size and recycle load, so you can spec the right feed preparation.
How can I avoid excessive wear in a crusher?
Wear is reduced by limiting specific energy, avoiding oversized feed, and matching liner material to the duty. DyssolPro doesn’t model wear directly, but because wear scales with energy and load, minimizing specific energy and recycle load for your size target steers you to the gentler operating point.
What causes agglomeration during fine grinding?
Below a few microns, surface forces make fresh fines re-stick — the practical limit of dry milling. The crusher model doesn’t resolve this, so if re-agglomeration matters you add an agglomeration unit downstream in the same DyssolPro flowsheet and study the net product across the two.
How do I choose between ball mill, hammer mill, and jet mill?
As a rule of thumb: ball mills for medium-fine grinding at scale, hammer mills for coarse-to-medium brittle feeds, jet mills for ultra-fine, contamination-free, heat-sensitive powder. DyssolPro turns that into numbers — calibrate the model to each candidate and compare predicted PSD and specific energy at your throughput.
How can I control temperature-sensitive materials during milling?
The usual route is low-energy, cryogenic, or inert-gas milling with active cooling. The crusher model has no thermal calculation, so in DyssolPro you control it by design — minimize specific energy for the size target and model the cooling and gas-handling units in the flowsheet to size the cooling duty.
How does classifier integration affect milling efficiency?
A closed circuit with a classifier is the single biggest efficiency lever: grind to cut size, recycle the oversize, stop over-grinding. DyssolPro simulates the loop dynamically — connect crusher and classifier with a recycle stream and optimize cut size and recycle ratio for throughput and product PSD.
How do I calculate specific energy consumption in milling?
Specific energy follows Bond’s law from power, work index, and mass flow against the size reduction achieved. That is exactly DyssolPro’s Bond model — it returns the specific-energy basis directly, so you can compare operating points and size targets on energy.
How can I simulate particle breakage and classification in a mill circuit?
Build it in DyssolPro: a crusher (Cone or Bond) plus a screen or classifier with a recycle stream. The simulator solves the loop dynamically, giving steady-state PSD, recycle load, and the effect of setting and cut-size changes — the basis for designing and optimizing the whole circuit.