Automatic control of impact crushers using size distribution measurement from a Visiorock camera

摘要

Impact crushing involves hitting the rock with sufficient force to make it shatter, and is thus a rather violent process by nature. It cannot be easily observed like compressive crushing, and therefore noticing abnormal behavior during daily operation is not easy. Impact crushers are not usually considered to be precision instruments and have not been targets for control efforts in the same extent as gyratory crushers. This paper describes a practical implementation of a control scheme for two impact crushers operating in parallel as secondary stage crushers in a large-scale aggregate production plant in the United Kingdom. The control is based on measuring crusher power draw, mass flows and the size distribution of produced rock. The size distribution is estimated using image analysis. The settings, i.e. rotor speed and impact plate gaps of the impact crushers, are then automatically adjusted to produce the desired end products. The system compensates for crusher blow bar wear and changes in feed material properties. A parallel method for detecting disturbances is monitoring the specific energy consumption of the crushers. This is the first time that such a control scheme has been implemented in a production plant. This paper describes the methods and controls used as well as future developments including an optimizing control based on a second, already installed camera.