Cobber Concentrate Liberation Spectra

This is a conditional, on size, grade distribution. Liberation was measured in 11 size ranges. All particles in the same size range are identified by an unique color. The distributuion is called conditional on size because each size adds up to 100%, i.e. there is no size distribution information associated to these numbers, and only the liberation characteristics at each size is shown. There are 12 particle types. Grade 0 represents pure Chert and grade class 100 represents pure Magnetite. Notice how particles above 355 microns are completely unliberated in this population. Also, notice the transition between unliberated and mostly liberated in the range 355 x 75 microns. We could say that the liberation size for this ore is about 106 microns, because bellow 106 microns we can separate Chert and low grade particles from Magnetite and high grade particles.

Note: This data was measured by Image Analysis of particles sampled in the real plant. There is quite a lot of controversy in the literature about liberation measurement. One of the reasons for this controversy is that even experienced researchers confuse the three fundamental liberation problems: measurement, prediction and simulation. In the keynote address to the Australian Comminution 98 conference, Dr. King decided to put a lecture together aimed at clearly defining these problems and thus putting an end to this confusion (hopefully). This keynote address was included with the student version of Modsim. If you are interested in liberation, you should view this presentation. Just double-click in the keynoteAudio.exe file in the Course folder contained in your Modsim installation folder. PDF files related to the keynote address are also included in this folder.