Accurate testwork and scale up is essential for project performance. So a key feature ofIsaMill technology is that all full production IsaMills can be accurately scaled up from testwork in a 4-litre (M4) laboratory mill using as little as 12.5kg of sample. The excellent scale-up of the IsaMill is a result of a combination characteristics including:
In ball mill laboratory tests 25mm balls in a small laboratory ball mill have different trajectories and interact differently with the shell lifters and ore particles than in a large production ball mill. Additionally while techniques like the Bond Work Index and "scale up factors" are useful for coarse grinding, they can significantly underestimate grinding needs below 100 microns.
In contrast, an ore particle in an IsaMill encounters small media particles (say 2-3mm) stirred at high speed, irrespective of the shell size. Our experience has shown very accurate scale up from laboratory IsaMill tests, so long as the sample is representative. The mill scales up accurately on both a power and product size distribution (PSD) basis.
A test program must rigorously account for energy measurement, size measurement, media size, classification and batch testing versus continuous operation. While Glencore Technology uses rigorous scientific design methods, and confirms the scale up on every plant. IsaMill installations always meet design.
So while your plant or laboratory is the best place to prove the liberation and process advantages of an IsaMill, once you have selected your target grind size the final mill scale up work should be done in an authorized IsaMill laboratory, using our standard mill and measuring equipment. This has been proven to give accurate scale up.
The best way to accurately size an IsaMill is by testwork on a representative feed sample.Glencore Technologyhas its own facilities and has also authorized a number of independent laboratories to conduct IsaMill tests. IsaMill test procedures consistently achieve one-to-one scale up, because the test rig configuration is the same as a full scale mill continuous feed, internal classifier, same grinding action and same grinding media.
The size of sample we need depends on the SG of the solid in your feed. It varies between just 12.5 and 22.5 kilograms. For a low SG, it's 12.5kg. For an SG of 3 (e.g. Copper), it's 15kg. For an SG of 3.5 (Copper, Lead, Zinc) it's 17.5kg. For an SG of 4 (Pyritic Gold) it's 20. And for an SG of 4.5 (Magnetite) you could expect 22.5kg.
Initial testing uses an M4 IsaMill to accurately determine the relationship between specific power draw and product size the "signature plot". Alternatively, fully self-contained M20 plant pilot rigs are available for on-site campaigns. M20 pilot rigs can determine power requirements while investigating media consumption and downstream processing performance on real plant streams.