Inferential measurement of SAG mill parameters III: inferential models

Inferential measurement of sag mill parameters IV: Inferential model validation

“…Previously, the inferential model results were assessed by comparison to the results of a process simulation model and found to give satisfactory results and thus deemed valid (Apelt et al, 2002b). Here the inferential models are furher validated on process data and incorporated in a multi-variable, model predictive control (MPC) simulation.…”

“…The solids that have water-like behaviour solids (solids of size < x m ) will always pass through the grate on being presented to the discharge grate. The calculation of the maximum discharge rate, d 0 , is detailed in an earlier paper (Apelt et al, 2002b) and elsewhere (Napier-Munn et al, 1996;Apelt, 2007). Equation (8) provides no information about the material in the rock charge larger than the grate aperture size (x g ).…”

“…Equation (8) provides no information about the material in the rock charge larger than the grate aperture size (x g ). Apelt et al (2002b) detail the estimation of the rock charge for particle sizes greater that the grate aperture size. The estimation involves the solving of a system of equations and utilises the assumption that the rock charge size distribution may be approximated by a Rosin-Rammler distribution and the rock charge fraction estimate from the next step (Step 3).…”

“…Details of the powerdraw calculation are found in an earlier paper (Apelt et al, 2001a) and elsewhere (NapierMunn et al, 1996;Apelt, 2007 [t]. Details of the mill weight calculation, particularly the kidney weight, M kidney [t], are found in earlier papers (Apelt et al, 2001a, Apelt et al, 2002b. The shell weight, M shell [t], can be estimated from plant knowledge or data, calculated according to mill dimension and lining specifications, or, be the result of a dynamic model of mill interior lining, as detailed in an earlier paper (Apelt et al, 2002a).…”

“…The perfectly mixed mill model is described elsewhere (Valery Jnr and Morrell, 1995;Napier-Munn et al, 1996;Apelt et al, 2002b;Apelt, 2007). The use of the steady state perfectly mixed mill model provides a valid estimate of the total mill feed, providing the calculation time between the discharge and charge estimates and the total mill feed estimate is relatively short.…”