SAG mill optimization insights by measuring inside the mill

*P. Shelley, I. Molina, D. Patsikatheodorou

Presented at Procemin GEOMET 2019


The paper shows how measurements from inside an operating SAG mill are now a reality. The paper discusses how the measurements might affect and enhance energy efficient mill optimisation. Energy efficient comminution is a pre-occupation of mineral processing researchers and practitioners. This is because the process of comminution is very inefficient and the cost of energy to process ore issignificant.To optimize energy usage, numerous researchers have developed models describing particle breakage energy in tumbling mills and attempted to align this to the efficient use of mill power. Most of the models are based on the first order comminution concepts. This has resulted in a separate field of research in which the constraints of each model by respective researchers are examined.

One could summarise these research outcomes by saying that the existing models are too simple and do not properly represent the complex system inside a tumbling mill. A study by United States Department of Energy, Office of Scientific and Technical Information with the University of Utah made efforts to measure the system elements of the inside of a mill.The team constructed an in-ball sensor system. The idea was abandoned at that time as the sensor system perished before the measurement could be of any use.

A further attempt to measure inside the mill was detailed by Martins in his doctoral thesis at McGill University Montreal, Quebec. Martins presented the study of an instrumented ball, a camera system and a DEM analysis to propose mill entropy measurement. The system was successful in laboratory scale with wood and plastic as the mill charge.

Given the status of current energy models and the progress toward measuring inside mills, it is reasonable to think that successfully combining real time data from inside the mill with mill optimizing mathematical models might provide an industry step-change to the efficacy of energy efficient mill optimization.This paper shows results of measurements inside a mill and explores the possibilities that the measures have in mill optimization.


Paul Shelley(1*), Ignacio Molina (2) and Dimitrios Patsikatheodorou (3)

1. VP Innovation, Moly-Cop, Global

2. Applications engineering, Moly-Cop, Chile

3. Processing Superintendent, Westgold Resources, Australia

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