A review of recent concentrator start-ups has been done to examine the methods that were used to design the grinding circuits for these new plants and the results achieved. A number of these start-ups were reported at SAG 2011. Large differences between design tonnage and actual tonnage were reported, with actual tonnage both above and below the design target by wide margins. This paper will examine some of these international plant start-ups, compare design tonnage versus actual tonnage achieved and review the sampling programs, the grinding test procedures, and mill design and sizing methods that were used. From this, dos and don’ts for effective grinding mill design have been derived.
At the same conference (SAG 2011), recommended design and test selection procedures were presented. These have been compared to the findings from the projects referred to above and are judged to be helpful in avoiding slow and delayed start-up and ongoing operational problems.