**MODULE 6 Comminution**

Models for comminution operations are comparatively well developed and comminution circuits are comparatively easy to model and simulate. Comminution processes are quite complex and it is necessary to understand what kind of information and data is required to model and simulate comminution circuits successfully. It is also necessary to have an appreciation of the different model types that are available. In this module we will restrict attention to an analysis of a conventional closed ball mill circuit. We will use the classic time-based approach that is usually associated with the name of Len Austin and then look at the modeling of the same circuit using the specific grinding energy method that is due to John Herbst and Doug Fuerstenau. Both methods use the breakage and selection function approach. Three different ores will be investigated in the exercises: limestone, taconite and a tough porphyry ore.

Objectives

1. Learn the use of basic breakage and selection function models for ball mills and learn to appreciate the role that is played by the parameters in these models.

2. Learn how to diagnose the operational effectiveness of a particular ball mill circuit.

This module is divided into two sections.

Classical breakage-selection function models that are based on the residence time.

Energy-specific grinding models.

Some results that were obtained by the instructor when running these exercise simulations can be downloaded here.

Details of the grinding models used in this module are given in sections 5.7,5.8 and 5.12 of the textbook and in Technical Notes 8.

These exercises do no more than sctratch the surface of the range of interesting comminution problems that can be tackled by simulation methods. They will however enable you get started with these important problems.