VertiMill® – Preparing the feed within floatable regime at lower specific energy

• The VertiMill® is preparing the feed for flotation at lower specific energy.
• Successful application of stirred mill for secondary and tertiary grinding duty.
• Reduction ratio plot for stirred mill performance evaluation.
• VTM receiving feed from AG/SAG and ball mill product.

A substantial proportion of large industrial mines process low grade finely disseminated ore bodies that require fine grinding to liberate valuable minerals. In response to increasing energy costs, the industry is seeking energy efficiency milling technologies that can process large tonnages. Stirred mills are an attractive option as they have the ability to grind to fine sizes (below 100 μm) at lower energy consumption than ball mills. The VTM is one type of stirred mill that has been used in mineral processing for secondary, tertiary and regrind duties and can be used in large throughput circuits at lower specific energy. The JKMRC has conducted an intensive survey program on VTM circuits in various grinding duties under the ‘Collaborative Research in Stirred Milling Technology’ project funded by Metso Minerals. The survey outcomes demonstrate that the VTM uses a low specific energy to reduce the particle size into the floatable regime by eliminating the coarser particles without producing excessive fines. This paper presents data on the performance of VTMs in secondary and tertiary grind duties that prepare feed for rougher flotation.