Poor feed arrangements affect crusher performance, liner life and the life of mechanical components, so it is crucial that you can identify and deal with any problems. In general terms, the goal is evenly distributed, non-segregated feed. It sounds straightforward, but issues can quickly develop if you’re not vigilant. Here are the most common problems to look out for, and some pointers for dealing with them.
Description: Segregation is when coarse and fine particles enter different parts of the chamber. Typically, smaller particles will accumulate at the bottom of the conveyor and large particles on the top. When fed into the crushing chamber the large particles accumulate on one side of the feed hopper and the small particles on the other side. Also, segregation will occur when material is transferred from one conveyor to another if changing direction at the same time. This will cause fine particles to accumulate on one side of the conveyor and coarse particles on the other side of the conveyor.
Possible solutions: There are a number of ways to address segregation. A feed distributor, splitter, hit plate, tube chute, centering chute, or feeder box could be useful depending on your circumstances. For an optimal solution, Sandvik Rotating Feed Distributor (RFD) can be installed above the hopper to evenly distribute the feed material.
Description: This is when material is unevenly fed into the crushing chamber, for instance if more falls into one side than the other. It can be caused by using a poorly aligned belt conveyor or vibrating feeder.
Possible Solutions: As with segregation, a feed distributor, splitter, hit plate, tube chute, centering chute, or feeder box could be helpful. A Sandvik Rotating Feed Distributor (RFD) can also be installed above the hopper to resolve this.
Description: A starved crusher is an inefficient crusher. If there is not enough material in the crusher to fill it, then productivity and reliability are compromised. Underfilling a crusher will cause increased liner wear and coarser product gradation – it also has a negative impact on the crusher product quality for the quarry industry, output particles will be flaky and elongated.
Possible Solution: Awareness is the key to fixing this problem – knowing that underfilled crushers are inefficient is a good start! The key is to match the crusher throughput capacity with the feed capacity, which can easily be done with the agile Sandvik cone crushers.
Description: Blocking occurs when a piece of material is too large to enter the chamber and gets stuck at the entrance. Bridging is a subtly different problem, and can often be trickier to resolve. It happens when one or more pieces that are small enough to enter the chamber cause a blockage because of the way they fall. This can happen if the feed is flaky or elongated and pieces span the entrance to the chamber. It can also happen if multiple pieces combine to form a blockage.
Possible Solutions: Adjusting the previous crusher’s CSS or changing the feeding arrangement could be helpful. Another solution would be to change to one of Sandvik’s multifeed mantles, such as the Flexifeed mantle for secondary applications, or our Oversize Breaker for tertiary applications. Both these mantles increase the allowable top size and help prevent bridging.
Description: This happens when feed material with a high amount of fines and moisture content form a conical shape on top of the spider cap. A misaligned feed can contribute to this, and it may cause the chamber to be unevenly filled or starved.
Possible Solutions: If there is only one level sensor it may give a false reading depending on which side of the chamber it is measuring. The solution here would be to have two level sensors to make sure the reading is accurate. Otherwise, visual checks should be done daily.