Sandvik Construction A world leader in Construction Module 2b How machinery factors affecting...
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Sandvik ConstructionA world leader in Construction
Module 2bHow machinery factors affecting crusher performance
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The major machinery influences on crusher performance, which are
1. setting
2. throw
3. chamber volume
4. speed
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Crushing concepts Machinery factorsWhat are we about to examine
Jaws Cone HSI VSI
Chamber Limited by plate
profile
Various & many Limited by position of
curtains and setting
on bottom curtain.
Different depth rotors
Throw Limited Various & many X X
Speed Limited Yes Yes Yes
Setting Yes Yes Yes X
Other Nip Angle Automation X Bi-Flow operation
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Crushing concepts Machinery factorsControl features
Nip Angle
Width
Gape
Flywheel speed
What features can be changed?
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Crushing concepts Machinery factorsJaw crushers Control features
What machine factors can be used to adjust the performance of a jaw crusher?
Closed side setting (C.S.S.)
Jaw plate tooth profiles
Speed
Stroke
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Crushing concepts Machinery factorsJaw crushers Control features
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All other parts in the crusher are ”only” there to hold the chamber in place or to create movement of the mantle.
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Crushing concepts Machinery factorsCone crushers Chambers
All crushing starts
with the chamber!
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Crushing concepts Machinery factorsCone crushers Why so many chambers?
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Which loaded EC chamber will produce the best performance
Should both feeds be fed to the same chamber?
Consider volumetric capacity
Consider mechanical advantage
Consider wear profiles
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Crushing concepts Machinery factorsCone crushers Why so many chambers
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C.S.S. reduction
Smaller volume in the crushing chamber
Risk of packingLower capacityHigher pressure
Higher energy consumption
Improved shape
Finer product
Higher net capacity
More power
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Crushing concepts Machinery factorsCone crushers CSS Consequence map
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Eccentricity Eccentricity
Increasing the eccentric throw-more energy to the material-more capacity-more nett product
MainshaftEccentric bush
Eccentric
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Crushing concepts Machinery factorsCone crushers Throw Altering the eccentric throw
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Small throw
Eccentric throw
Increased average chamber volume Large throw
Increased throw resulting in increased chamber volume results in• higher capacity• more stones in the chamber to compress
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Crushing concepts Machinery factorsCone crushers Increased throw Larger avarage volume
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Throw increased
More crushingstone-against-stone
Packing riskHigher capacity More power needed
Higher powerconsumption
Improved shapeHigher net capacity
Largeraverage setting
Higher flow Higher torqueIncreased
compression
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Crushing concepts Machinery factorsCone crushers Throw alteration Consequence map
1. Best results are achieved when the optimum chamber is fitted to the crusher.
2. The optimum throw has a major influence on obtaining best results
1&2 are volumetric issues and may well determine the utilisation of the crusher ---remember all crushers work best when continuously choke fed
3. The crusher setting has an effect on both volume and reduction.
4. Is the feed condition correct—have you removed the risk of packing
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Crushing concepts Machinery factorsCone crushers Take home message
All crushers have a volumetric and a mechanical limit
Toughness of material, feed material particle size analysis, volume and reduction ratio all play their part in the ability of the crusher to perform the duty over an acceptable lifecycle.
If any combination of these factors overstress the mechanical capability of the crusher (demands too much energy from the motor) it will be necessary to reduce the influence of another.
Eg. The demand for greater throughput at the expense of reduction.
Work done(energy)=volume x toughness x reduction ratio
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Crushing concepts Machinery factorsTake home message