This is the starting point for understanding how cone crushers work - and how they can improve the productivity of your mine or quarry.
The basic principle is simple: the material to be crushed (the feed material) falls into the crushing chamber. The mantle is a moving part that rotates in an eccentric motion. That is, it does not remain perfectly centered - it oscillates slightly as it rotates, constantly changing the gap between the mantle and the concave surface (the ring outside the mantle that remains in a fixed position). As the mantle moves, it crushes the material against the concave face at the point where the gap is smallest (the stones in the feed are also compressed against each other - this is known as inter-particle crushing).
As the feed is crushed, it drops and leaves the crusher through space at the bottom. The eccentric rotation of the mantle means that at any given time this space is narrowest at one point and widest at another. The widest distance is called the open side setting (OSS) and the narrowest distance is called the closed side setting (CSS). These settings are important. the OSS is the maximum distance between the concave surface at the bottom of the crusher and the mantle, and therefore it determines the maximum size of the discharge product. the CSS, as the minimum distance between the concave surface and the mantle, is the final crushing zone and is critical in determining product size, energy consumption, and crusher capacity.
In a cone crusher, the importance of feed size cannot be overemphasized. It is critical to know the size distribution of your raw material as accurately as possible. The cone crusher is calibrated to achieve specific results, maximize productivity and minimize wear, but any calculation will be undermined without an in-depth understanding of what is in the crusher. Sampling is an important part of the crushing process to ensure you understand the size distribution of the feed. Regular sampling is critical, especially when blasting, mining, or any other upstream process changes.
To ensure that your crusher delivers the product you need and maximizes its efficiency and productivity, there are a number of potential problems you should be aware of.
The main reason for poor crusher performance is the choice of crushing cavity. If the fit between the casing and the concave (combined with the eccentric throw setting) is incorrect, the optimum reduction ratio cannot be achieved. The crusher manufacturer has found that the wrong crushing chamber setting can cause you to lose up to 40% of your reduction ratio.
Poor feeding conditions can also be a factor. Irregularities in the feed in any form - whether from separated feed, unaligned feed or clogging or packing in the chamber - can lead to performance losses of up to 30 percent. Uneven distribution of the material in the chamber means that Hydroset - a mechanism that exerts upward forces on the mantle - cannot maintain uniform pressure. Depending on the type of irregularity, poor feeding conditions can lead to fluctuations in pressure over time or in different parts of the chamber. Any fluctuation in pressure means that the optimum force cannot be consistently delivered, so of course, the performance of the crusher will be reduced.
These are the two main reasons for poor crushing performance, but choosing the wrong mantle or a poor chamber profile or design can also lead to a loss of reduction ratio. Surprisingly, the wrong choice of alloy has no effect on the reduction ratio (although it can affect the life of wear-prone parts in the crusher).