Apr 7, 2020 Aggregates blog

Selecting crushings chambers for cone crusher

Antti-Pekka Otava
Antti-Pekka Otava
Product Manager, Aggregates Crushing Solutions
Jukka Salovaara
Jukka Salovaara
Global Business Support Manager
There is a variety of things to take into consideration when selecting a cone crusher chamber profile to best suit your needs. An inadequate liner profile can lead to increased downtime through excess liner wear, low efficiency and, in some cases, even mechanical damage to the crusher.
Illustrative figure of HP cone crusher liners.

To ensure the suitability of the liner profile for its application, it is important that there is data on which to base your decisions. Here we go through five things that should be defined and why. Get optimum capacity and maximum wear life of wear parts by considering these points from the perspective of your circuit and production. None of these points on its own should be the rationale for choosing the liner.

  1. Feed grading

Feed should always be well graded with no gaps in the size distribution, which generally means an even distribution of different-sized feed material up to the defined maximum size. Fines (for example, 0–4 mm) should be screened out before the material is fed to the crusher as the fines may cause packing: this is a force overload and can be seen as adjustment ring movement. There are differences within different product ranges, and Nordberg GP Secondary cone crushers, for example, can handle a certain amount of fines in the feed due to their steep vertical cavity and adjustable stroke length.

As a rule of thumb:

  • Oversize feed material decreases capacity and can cause abnormal wear of the liners.
  • Too small feed size for the cavity increases the wear of the bottom part of the liners and may cause poor utilization of the wear parts.
Example of the effect of different kinds of feed sizes.
From left to right: good feed material level, too big feed material and too small feed material.
  1. Crusher adjustment (CSS)

The closed side setting (CSS) defines the reduction ratio in cone crushers and has a significant effect on product gradation, capacity, and power draw. The closed side setting is measured from the bottom of the mantle to the bottom of the bowl liner at their closest point during the gyrating cycle.

CSS should be close to the required product. The setting is too small if the adjustment ring is moving on the main frame. This is discussed in more detail in the 12 tips to maximize cone crusher productivity blog post. Summarizing, larger setting → product size increases, capacity increases, power draw decreases.

 

Example: The HP crusher chamber selection table.
Example: The HP crusher chamber selection table shows the minimum opening settings. However, the presented settings are provided as a guide only. The actual minimum setting is at which the crusher will operate without causing ring bounce.
  1. Feed type

Feed material characteristics such as gradation, bulk density, moisture, clay content, and crushability have a significant impact on crusher capacity.

For example, when feed material crushability changes from 40% to 20%, secondary and tertiary crushing loads increase. Harder material turns crusher product coarser, which increases the load of the closed circuits. Also, KW/ton product rises due to the material being harder. This kind of case is an example of the significance of liner materials. Different kinds of manganese alloys are being developed for different kinds of feed materials.

  1. Desired product grading

 

Graph showing desired product grading.

This goes hand in hand with the CSS (Crushing adjustment). You set your crushing adjustments such as CSS accordingly to obtain the desired product grading. For example, the Metso MX Multi-Action cone crusher has many other parameters to fine-tune the grading. This is taken into consideration along with other aspects when choosing the crusher in the first place, but it is also an important thing to consider if you are looking to optimize your plant. It might be that the tertiary crusher is overloaded and changing the liners of the secondary crusher eases it out without major changes in the circuit.

  1. Crusher operating speed (RPM)

Generally, a higher speed creates a finer product gradation curve and better product shape, which is important when producing the end product for most construction applications, while operating the cone crusher at the lower end of its speed range will increase the cavity volumetric throughput and the product gradation curve can be altered to produce fewer fines. Crusher operating speed is adjusted by changing the diameter of the crusher and motor sheaves.

Each cone crusher has several cavity options with different feed openings and setting ranges. The correct cavity can be selected based on the feed size, setting, and application. Overall, it is essential to keep in mind that the crusher is just one part of a crushing circuit. Its performance depends on the proper selection and operation of feeders, conveyors, screens, electric motors, drive components, and feed silos which are part of the circuit. All the elements should be examined as part of an entity to get the most out of the production.

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Secondary, tertiary, and quaternary crushing
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