1. Never crush coal that is already product size. Screen out undersize before crushing. Each time sized coal goes through a crusher, fines are produced, even if the incoming coal is smaller than the crusher setting. This is valid even when primary crushing.
2. Choose the right type of crusher. Double roll crushers have proved themselves to be the most effecient type of machines in the coal industry.
3. Use the correct crushing ratio. Crushing ratio is defined as the ratio of input size to output size. The ideal ratio is
2 : 1.3 : 1 is possble but anything above that ratio causes a serious decrease in crushing effeciency.
4. Use a crusher with th right roll diameter with respect to the desired input and output size. Large pieces of coal fed to small diameter rolls produce a rolling effect of the coal as the teeth battles to grip the coal, thereby reducing throughput tonnage and increasing fines and segment wear. The nip angle, the angle from the horizontal where the rolls grip the coal, must always be as small as possible. Reduce the crushing ratio nip if the angle is too large or use larger diameter rolls.
5. One fo the most important aspects of the crusher design is the correct segment tooth profile. Let your crusher manufacturer know what product you desire and we will give you the correct profiles. If your product changes, contact us and we will advise you wether your present profile can still be used or if the profile should be changed. Power consumption is very largely influenced by the correct selection of the tooth profile.
6. The roll speed is also important. Always contact your crusher manufacturer before altering the roll speed with respect to the imput size and crushing ratio. Too high a speed can result in slippage with a resultant increase in fines and segment wear.
7. When doing cost cutting exercises, do not try and reduce capital outlay on your crushing curcuit to the detriment of the crushing effeciency. The capital you save initially will be lost later on a continuous basis as you create extra fines and lower profit products.