The need for exponential change

 

The mining industry is at a crossroads.  In a time of unpredictable commodity prices, depleting reserves and falling grades create productivity challenges.  Viable ore bodies are increasingly located in physically challenging and remote locations.  Energy costs continue to rise.  The industry needs technical innovation that offers exponential change in costs and productivity.

 

Grinding - the status quo

 

For too many years, the mining industry has relied upon rotary tumbling mills, in particular the Semi Autonomous Grinding (SAG) mill to grind materials.  The SAG mill has predominated grinding circuits for decades, despite poor energy efficiency, high capital cost, and difficulties in shipping to remote sites.

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Why is a SAG mill inefficient?

 

Most energy (80% or more) in a tumbling mill is consumed by inter-particle friction as the mill tumbles.  While this produces a minor amount of abrasive grinding, this energy is largely wasted, and leads to "overgrinding."  By contrast, a much smaller percentage of energy (20% or less) is used to lift material and metal balls with lifters, then release them for impact breakage.  Impact breakage is where useful grinding occurs, and is far the most efficient means of grinding.