487 Table 3 – Boyne AG mill CCRD experimental plan as reported in Vizcarra et al. (2018). Run Block Feed A% Feed B% Mill power (kW) 1 2 34 46 104 2 46 46 131 3 40 40 118 4 34 34 131 5 40 40 118 6 46 34 104 7 3 40 30 118 8 40 40 118 9 40 50 118 10 40 40 140 11 40 40 118 12 40 40 95 13 50 40 118 14 30 40 118 15 1 46 34 131 16 40 40 118 17 34 34 104 18 40 40 118 19 34 46 131 20 46 46 104 Analysis of CCRD results is with regression, from which 3D plots of the response can be generated. These are shown in Figure for a key size marker, the percent passing 75 µm in the mill discharge. Figure 5 - Surface plots of AG product -75 µm (%) at mill power draws of (a) 120 kW and (b) 130 kW (reproduced from Vizcarra et al. (2018)). The results indicated that reducing excessive fines production could in fact be achieved by targeting certain feed blends, while maintaining high mill power draw set points, as shown in Figure b. An unexpected outcome was the effect of tramp metal in the mill load, which was removed by the operations team approximately once per week. This took place right before the commencement of the final block of runs, such that the third block corresponded to a ‘clean’ mill, devoid of tramp metal in its load. This effect is shown in Figure , where it can be seen that the removal of tramp metal from the mill led to a strong reduction in
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