IsaMill™ is a transformation in grinding technology based on high intensity stirred milling. It was initially developed for fine grained orebodies that needed a step change in processing efficiency to be economic and in the last decade has crossed over into coarser mainstream applications. Compared with conventional grinding, the IsaMill™ significantly reduced the energy, media cost and capital cost of fine grinding. Just as importantly, the processing advantages of inert grinding greatly improved metallurgical performance compared with conventional steel media.

The patented IsaMill™ is unlike any other grinding mill:

• It is very high intensity – 300kW/m³, compared with typically 20kW/m³ for ball mills. This means it is easily installed in a small area.
  
• It produces a very sharp size distribution in open circuit. This is due to 8 grinding chambers in series, closed with an internal centrifugal classifier. The internal classifier means simple operation, no screens to block or maintain, and allows low cost natural grinding media to be used (eg sand).
  
• It has high energy efficiency – because it uses small media suited to the target grind size.
  
• The inert grinding environment has profound benefits for the chemistry of flotation and leaching. The IsaMill™ is an intense chemical reactor, creating fresh mineral surface in a closed inert environment. It does this quickly – typical residence time is 90 seconds. This creates a unique opportunity to control the surface chemistry of particles.
  
• Unlike other stirred mills which are vertical, the horizontal configuration of the IsaMill™ has allowed rapid scale up, with the latest installation a 3MW unit.
  

IsaMilling™ has allowed several fine grained deposits to become economic. It now promises to change the way we design circuits for more conventional ores, offering step changes in energy efficiency and metallurgy. The large scale 3MW M10,000 and ceramic grinding media have enabled this transition to mainstream applications. The benefits have been demonstrated in full scale commercial applications since 2006.

The IsaMill™ is marketed by Xstrata Technology, with headquarters in Brisbane, Australia and offices located in Vancouver, Canada; Santiago, Chile and Johannesburg, South Africa. Xstrata operates 16 IsaMills™, and developed the technology together with our technology partner Netzsch. Xstrata Technology provides detailed flowsheet design, installation and commissioning support and Netzsch provide the mill manufacturing and design expertise. Netsch have been manufacturing grinding mills since 1860, and high intensity stirred mills for manufacturing applications since 1950.

The IsaMill™. A transformation in grinding technology.