Jaw Crusher Simulation for Crushing Plant Design
Model jaw crusher throughput, product gradation, and CSS sensitivity within a full plant flowsheet, so primary crushing decisions are based on circuit-wide data, not isolated capacity tables.
Sizing a jaw crusher in isolation misses the circuit context
The jaw crusher is almost always the starting point for a hard rock crushing plant. Getting it right matters: undersize the jaw and the whole plant is throughput-limited; oversize it and you have excess capital cost sitting idle while downstream stages are the real constraint.
Most jaw crusher sizing decisions are made using capacity tables from vendor datasheets. These tables show throughput at various CSS settings for a reference material, which is useful, but it is not the same as modelling how the jaw crusher performs in your specific circuit, with your feed gradation, your downstream equipment, and your target products.
Jaw crusher simulation in Quorr puts the jaw crusher into the context of the full plant, so you can see how CSS changes affect not just primary throughput but product gradation all the way to the final stockpiles.
Jaw crushers as primary crushers
Jaw crushers are used almost exclusively at the primary stage in quarry and aggregate plant designs. Their open-top chamber accepts large, irregular feed from blasting or run-of-mine material, and compression between the fixed and swing jaw plates reduces it to a size that downstream equipment can handle.
A jaw crusher's maximum recommended feed size depends on the manufacturer's definition of the feed opening, chamber geometry, and operating practice. Many designs use a rule of thumb where maximum feed is lower than the full feed opening dimension — often around 80–85% of the relevant opening — but manufacturer data should always take precedence over rules of thumb.
The output of a jaw crusher is a gradation, not a single size. A jaw set at 125 mm CSS does not produce all 125 mm material — it produces a distribution of sizes, heavily influenced by the feed gradation, rock strength, and moisture content. Downstream screens and secondary crushers determine the final products. The jaw discharge is the feed to the next stage, and its gradation shape matters as much as its top size.
Closed-circuit jaw arrangements are possible but less common at the primary stage. Most primary jaws run in open circuit, with closing occurring at the secondary or tertiary stage using cone crushers and screens.
How jaw crusher output affects the rest of the circuit
The jaw crusher's CSS setting and discharge gradation directly affect what the secondary stage sees. Tighten the jaw CSS and the secondary crusher receives a finer feed, which reduces secondary crusher load but may increase the proportion of fines entering the secondary screen. Widen the jaw CSS and the secondary sees a coarser feed, which increases secondary throughput but may increase the recirculating load if the secondary runs in closed circuit.
This interdependency is why jaw crusher simulation in isolation is less useful than simulating the jaw crusher as part of the full circuit. The decision about jaw CSS is not just a primary stage decision — it ripples through every downstream stage.
All capacity and gradation values in Quorr are illustrative estimates based on the equipment data and feed conditions you enter. Actual performance depends on manufacturer specifications, rock strength, feed gradation, moisture, liner condition, and operating practice. Quorr results do not constitute manufacturer guarantees.
Key jaw crusher terms
Gape
The distance between the jaw plates at the feed opening, measured at the top of the crushing chamber. Gape determines the maximum lump size the crusher can accept.
Width
The dimension of the feed opening perpendicular to the gape. Together, gape and width define the feed opening size, often written as width × gape (e.g. 1200×900 mm).
CSS (closed side setting)
The minimum gap between the jaw plates at the bottom of the crushing chamber. CSS is the primary control over product size. A smaller CSS produces a finer product with lower throughput.
OSS (open side setting)
The maximum gap between the jaw plates at the bottom of the chamber, at the point of maximum opening. OSS = CSS + stroke. Material larger than OSS cannot pass through the chamber.
Nip angle
The angle between the fixed and swing jaw at the point of contact with the feed material. A nip angle that is too large causes material to be thrown back up the chamber rather than drawn in.
Reduction ratio
The ratio of feed size to product size. For jaw crushers, reduction ratios of 4:1 to 6:1 are typical. Higher reduction ratios increase wear and may reduce throughput.
Choke feed
A choke feed condition occurs when the crushing chamber is kept full of material. Choke feeding generally increases throughput and improves product shape, but requires a consistent, even feed rate.
How jaw crusher simulation works in Quorr
In Quorr, a jaw crusher is a node in the plant flowsheet with defined input conditions (feed gradation, material density, fresh feed rate) and calculated output conditions (discharge gradation, throughput).
Feed gradation and CSS
The simulation uses the feed gradation you define and the CSS you set for the jaw crusher to calculate the discharge gradation. A tighter CSS shifts the discharge toward finer material, while a wider CSS produces a coarser discharge. The exact relationship depends on the equipment's performance data and the feed characteristics.
Throughput calculation
Throughput is calculated from the equipment performance data you select and the CSS you set. Reducing CSS generally reduces throughput; increasing CSS increases throughput, within the machine's rated range. The relationship is not linear and varies by machine model, feed material, and rock strength.
Example only. Actual capacity depends on manufacturer data, chamber geometry, CSS, feed gradation, rock strength, moisture, bulk density, liner condition, feed method, and operating practice.
Circuit context
Once the jaw crusher discharge gradation is calculated, Quorr passes it to the next stage in the circuit. If a primary screen follows the jaw crusher, the calculation shows how much material passes the screen aperture and how much is oversize. If the jaw feeds directly to a secondary crusher, the jaw discharge becomes the secondary feed gradation.
Simulating a jaw crusher in a plant circuit
Define the feed material
Set rock type (granite, limestone, basalt), bulk density, and feed gradation from run-of-mine or blasting. Define a feed top size appropriate to the crusher's feed opening.
Add the jaw crusher
Select a jaw crusher from the equipment library, or enter feed opening dimensions and capacity data manually. Set the CSS for the initial simulation.
Connect downstream equipment
Add a primary screen, secondary crusher, or conveyor to the jaw crusher discharge. Build the full circuit to see how the jaw's output affects downstream performance.
Run the simulation
Quorr calculates jaw crusher throughput and discharge gradation, then propagates results through all downstream stages. See throughput and product data at every node.
Compare CSS settings
Change the jaw CSS and re-run. Compare the circuit-wide impact of tighter versus wider CSS on product gradation, secondary crusher load, and final product tonnages.
What you can compare with jaw crusher simulation
- Throughput at different CSS settings for the same feed — how tightening or widening CSS changes primary output
- Discharge gradation at each CSS and the resulting feed to the secondary crusher
- Impact of jaw CSS on secondary crusher recirculating load and product yield
- Effect of feed gradation variability on jaw throughput and downstream performance
- Comparison of different jaw crusher sizes for a given throughput target
- Open-circuit jaw versus closed-circuit jaw (with primary screen recirculation) for product quality
- Jaw crusher as primary stage versus gyratory or impact crusher for the same application
Simulation limits and engineering judgement
Quorr is a design and scenario comparison tool. It helps users estimate mass balance, product yield, utilisation, and likely bottlenecks, but it does not replace manufacturer guarantees, detailed engineering design, site trials, pilot testing, commissioning data, or professional judgement.
Jaw crusher simulation is particularly sensitive to feed gradation assumptions. The same machine can perform very differently depending on whether feed is fine-dominant or coarse-dominant, and whether fines content is high. Use simulation results to compare options and understand the sensitivity of your design to feed gradation changes, not to predict absolute throughput values.
Who uses jaw crusher simulation
Engineers
Size the jaw crusher correctly for the target throughput and downstream circuit. Validate CSS settings and feed conditions before procurement.
Quarry operators
Understand how changing the jaw CSS affects the whole plant, not just the primary discharge. Plan CSS adjustments based on circuit-wide data.
Consultants
Compare jaw crusher options for a client's plant and show the circuit-wide impact of each choice, including secondary stage performance and final product quality.
Simulate your jaw crusher in the context of your full plant
Register your interest and we will be in touch when Quorr is ready for your plant design.
Frequently asked questions
What is CSS in a jaw crusher and why does it matter?
CSS stands for closed side setting, the minimum gap between the jaw plates at the bottom of the crushing chamber. It is the primary control over product size. A smaller CSS produces finer product with lower throughput; a larger CSS produces coarser product with higher throughput. Actual values depend on the specific machine, feed gradation, rock strength, and operating conditions.
When should a jaw crusher be used rather than a gyratory or impact crusher?
Jaw crushers are well suited to primary crushing of hard, abrasive rock at moderate to high throughput. They handle irregular, blocky feed from blasting well and have a robust mechanical design. Gyratory crushers are used where very high primary throughput is needed. Impact crushers are better suited to softer, less abrasive rock where product shape is a priority.
Can a jaw crusher run in closed circuit?
Yes, though it is uncommon at the primary stage. A jaw crusher in closed circuit with a primary screen will recirculate oversize back to the jaw, improving product consistency but adding recirculating load to the crusher. Closed-circuit operation is more commonly associated with secondary cone crusher circuits.
How does feed gradation affect jaw crusher performance?
Feed gradation affects both throughput and discharge gradation. A coarser feed (larger top size, less fines) produces more material that needs full reduction through the chamber. A feed with significant fines (material already below the CSS) passes through more quickly and reduces the crusher's effective workload. Quorr models this using the feed gradation you define.
Does Quorr model jaw liner wear and its effect on performance?
Quorr models steady-state performance at defined CSS settings. It does not currently model progressive liner wear over time. For liner wear analysis, manufacturer-specific wear modelling tools are more appropriate.