MILL PULSE MEASUREMENT AND OPTIMIZATION

The grinding efficiency of semi autogenous milling or ball milling depends on the tumbling motion of the total charge within the mill. Utilization of this tumbling motion for efficient breakage of particles depends on the conditions inside the mill. However, any kind of monitoring device to measure the conditions inside the mill shell during operation is virt ually impossible due to the sever environment presented by the tumbling charge. An instrumented grinding ball, which is capable of surviving a few hours and transmitting the impacts it experiences, is proposed here. The spectrum of impacts collected over 100 revolutions of the mills presents the signature of the grinding environment inside mill. This signature could be effectively used to optimize the milling performance by investigating this signature’s relation to mill product size, mill throughput, make-up ball size, mill speed, liner profile and ball addition rates. At the same time, it can also be used to design balls and liner systems that can survive longer in the mill. The technological advances made in electronics and communication makes this leap in inst rumentation certainly viable. Hence, the instrumented grinding ball offers the ability to qualitatively observe and optimize the milling environment.

An instrumented load cell package that can measure the force of impacts inside the grinding chamber of a mill is developed here. The signal from the instrumented load cell package is interpreted in terms of a histogram termed as an impact spectrum which is a plot of the number of impacts at a specific energy level Sagainst the energy. It reflects on the average force regime of the mill.