Abstract:

As the mineral processing industry strives to achieve more efficient grinding capabilities, the use of stirred milling is becoming a more recognised technology for optimising performance and reducing carbon footprint. This has been reflected in the market through the investment in developing larger rolled ceramic media (up to 20 mm) and the release of large stirred mill designs (up to 12.5 MW).

When the IsaMill™ was first introduced to the market in the late 1990s, the target grind size was in the sub 10-micron range, which opened up previously un-treatable orebodies. Developments with larger ceramic media in mid-2000s allowed the IsaMill™ to operate with a feed of 400 microns (F80) and a top size of 1 mm from using a top size of 6mm media. With the recent development of larger media on the market (>6mm), Glencore Technology (GT) has been investigating expanding the duties of the IsaMill™ - as media top size determines what your F80 can be for a stirred mill.

Recently, GT conducted a Secondary Grinding trial at Hudbay’s Stall Mill in Manitoba, Canada. The aim of this trial was to conduct a proof-of-concept test to demonstrate the effects of 8mm and 10 mm ceramic media in an IsaMill^TM and investigate the influence of media SG. In these trials, substantial reductions (>50%) in specific energy were observed compared to tumbling mills; this paper outlines the findings of that large-scale testwork campaign and the potential for the IsaMill™ operating in this duty.

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Mr. Trevor Weir