Calculation of variance and covariance of sampling errors in complex mineral processing systems, using state-space dynamic models

This paper presents a method to calculate the variance and covariance matri x V of the integration errors of the measured flow species in a complex min eral processing unit. The integration error is due to the interaction betwe en the sampling strategy and the dynamic variations of the stream propertie s. First, a general formula is developed to relate V to the autocovariance matrix V-yy of the flow species in the different streams of the unit. Then V-yy is estimated using a dynamic model of the process. This dynamic model is obtained by assembling summators, separators and transfer functions into a state-space formulation. Two examples of the method are given: one for a flotation circuit and one for a leaching tank. (C) 1998 Elsevier Science B .V. All rights reserved.