Eight consecutive grinding chambers, patented product separator and short residence times means the mill constantly delivers sharp product size distribution without external classification.
The IsaMill™ is a closed mill. Slurry travels through the mill in a 'plug' flow pattern through consecutive grinding discs. Media recirculates between the rotating discs distributing grinding action throughout the IsaMill™. Grinding is by attrition and abrasion of the particles in contact with the high speed, small, circulating media. This breakage mode produces very fine sized particles at relatively low power consumption.
At the discharge end of the IsaMill™, slurry and media reach the patented product separator. Media is centrifuged out to the shell and is pumped back with some of the slurry to the feed end of the mill. This action retains media in the IsaMill™ without the need for fine screens while the ground discharge slurry exits the centre of the product separator.
The high efficiency of the IsaMill™ comes from its ability to use small media, with high surface area and high media/ particle collision frequency. Small media can still grind coarse feed because of its high speed – up to 22 m/sec. The high power intensity results in a small mill with short residence times – less than a minute – which avoids overgrinding. This, together with the 8 consecutive stages of grinding and product separator, produces a sharp size distribution without external classification.
This is one of the keys to the IsaMill™ energy efficiency – energy is directed to coarser particles and not wasted on fines, which leave the mill quickly.