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Previous studies at Anglo Research investigated comminution circuits/flowsheets that produce liberated grind sizes at improved energy efficiency. These would also have to be economic when considering factors such as capital expenditure, operational expenditure, sensitivity to feed variability, safety, and relining time. The further work described here records the piloting of a 'one crusher-VRM and HPGR-VRM circuit at Loesche GmbH using Gemsberg ore. The energy efficiency of the VRM, or vertical roller mill, has been previously identified, and as a dry process it allows greater control of the percentage solids in the flotation feed. It also reduces the galvanic effect of steel grinding media on the mineral surface chemistry as the HPGR-VRM circuit is largely autogenous., Previous studies at Anglo Research investigated comminution circuits/flowsheets that produce liberated grind sizes at improved energy efficiency. These would also have to be economic when considering factors such as capital expenditure, operational expenditure, sensitivity to feed variability, safety, and relining time. The further work described here records the piloting of a 'one crusher-VRM and HPGR-VRM circuit at Loesche GmbH using Gemsberg ore. The energy efficiency of the VRM, or vertical roller mill, has been previously identified, and as a dry process it allows greater control of the percentage solids in the flotation feed. It also reduces the galvanic effect of steel grinding media on the mineral surface chemistry as the HPGR-VRM circuit is largely autogenous.

A description is given of the advanced control systems installed in two of Anglogold Ashanti's Au ore grinding circuits, with three lines at Mponeng and six lines at Kopanang. The control system is based on the OCS software and combines the flexibility of an expert system with fuzzy logic and the power of an on-line dynamic phenomenological model, used as an advanced soft sensor of the whole process. The history and implementation methodology is described and the resulting increases in throughput and Au recovery are analysed with particular reference to the effects of improved control of particle size., A description is given of the advanced control systems installed in two of Anglogold Ashanti's Au ore grinding circuits, with three lines at Mponeng and six lines at Kopanang. The control system is based on the OCS software and combines the flexibility of an expert system with fuzzy logic and the power of an on-line dynamic phenomenological model, used as an advanced soft sensor of the whole process. The history and implementation methodology is described and the resulting increases in throughput and Au recovery are analysed with particular reference to the effects of improved control of particle size.