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Metso: It pays off to Invest in Multi-stage Crushing Process

Two of the most common crushing applications are two- and three-stage crushing processes. When deciding on whether to have two or three crushing stages, certain factors need to be considered in order to optimize the crushing process and achieve the best capacity and cost-efficiency.

According to Metso's experts these factors are:

  •   type and size of the crushed rock
  •   desired end-product size
  •   desired quality of the end product

An optimal crushing process with the right number of crushers helps to avoid breakages, optimize the wear of parts and operate the crushers in their optimal operating range.

Feed material characteristics impact on what kind of crusher should be used and what kind of settings are suitable for processing the feed material. For example, the size and type of feed material determines the achievable reduction ratio of the crusher.

For example, when producing 0/32 mm end product, two crushers may be enough to produce the desired end product cost-efficiently and in accordance with the quality requirements. However, when the desired size of the end product gets smaller, for example, 0/16 mm, two crushers may not be enough, and it might be worth considering adding a third crusher to the crushing process for optimal aggregates production, say the Metso experts.

But how to determine the number of crushers in practice? Here's a practical tip: Check the maximum feed size of the primary crusher and compare that to the desired final product size. As a guiding principle, a reduction ratio of 4 is generally considered as the maximum of any jaw or cone crusher. If the ratio of feed material and end product size is 16:1, you need 2 crushers, and this is calculated by multiplying 4 with 4. If the ratio would be, let’s say 20:1, you would need 3 crushers, advice from Metso.

One common counterargument for not investing in additional crushers is naturally to save money. It may have negative effect on both final product quality and quantity/capacity. There will be an inevitable increase in cost per ton of production. This includes excess wear, but it can also be seen as not getting the most out of the investment.



Prime Technologies Ltd.