Abstract:A flotation bank is a serial arrangement of cells. How to optimally operate a bank remains a challenge. This article reviews three reported strategies: air profiling, mass-pull (froth velocity) profiling and Peak Air Recovery (PAR) profiling. These are all ways of manipulating the recovery profile down a bank, which may be the property being exploited. Mathematical analysis has shown that a flat cell-by-cell recovery profile maximizes the separation of two floatable minerals for a given target bank recovery when the relative floatability is constant down the bank. Available bank survey data are analyzed with respect to recovery profiling. Possible variations on recovery profile to minimize entrainment are discussed.
The performance of sensorless vector control schemes is seriously degraded at low speed operation, becoming impossible to operate constantly at standstill. There are three main reasons for this degradation in low speed senseless performance. First, offset on the estimation of the back-EMF that causes drift in the open integration of the stator model of the machine. Second, unaccounted nonlinearities of the inverter distort the back-EMF estimation. Finally, errors on the estimated machine parameters, mainly stator resistance cause phase error on the back-EMF estimation. This paper deals with the first two phenomenon to achieve sensorless stator flux orientation and speed feedback by means of an MRAS observer, down to fractions of a Hertz.
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