Ultrafine Grinding and the IsaMill™ Technology
The IsaMill™ is a large-scale energy efficient continuous grinding technology specifically developed for rugged metalliferrous applications. Glencore Technology supplies the IsaMill™ technology to mining operations around the world, with over 110 mills installed worldwide. The IsaMill™ uses a very high energy intensity of 300kW/m3 in the grinding chamber, resulting in a small footprint and simple installation. The IsaMill™ can be scaled up directly from small scale laboratory tests.
Glencore Technology will provide the IsaMill™ as a packaged Grinding Plant, consisting of the mill, slurry feed and discharge systems, media handling system, all instrumentation and control and all structural steel and platforms. Access to the mill and maintenance is simplified by the low operating aspect of the IsaMill™ and the associated grinding plant. Maintenance of the IsaMill™ is similar to routine maintenance for a slurry pump.
The IsaMill™ produces a sharp size distribution in open circuit, as the feed must pass through multiple distinct grinding zones in series before reaching the Product Separator. This plug flow action ensures no short circuiting, and efficiently directs energy to the coarser feed particles. The IsaMill™ can be operated in open circuit at high slurry density, which is a key advantage for the leaching circuit, as the entry of water to the leach is limited, simplifying the water balance.
The IsaMill™ uses inert ceramic grinding media ranging from 1.5 mm to 6.0 mm, that produces clean, polished mineral surfaces resulting in improved leaching kinetics. A steep particle size distribution is produced in the mill. The 98% passing size in the mill is typically less than 2.5 times the 80% passing size, and very little coarse material enters the leaching circuit, resulting in very high leach recoveries.