Application of control units VAZM-2U in ore grinding

Abstract

This paper considers the results of research work aimed at developing control systems to control ore grinding processes that would be compatible with the control unit VAZM-2U developed by Soyuztsvetmetavtomatika. The underlying principle concerning the unit is that grinding of ores with different mineralogical compositions is governed by the same common regularities in correlation between the physical processes that develop in grinding circuits and the defining process parameters. A grinding mill is fed with ore that has varying physical and mechanical properties, and this can lead to accumulation of material in the mill. Indicators of the probable overload condition include mill vibration level and active power draw of the mill drive motor. The point at which the overload condition has arrived is determined by analyzing active power draw and reverse vibration trends. It is demonstrated that a mill overload condition may take place in those time intervals when both the vibration level and the active power draw of the mill motor fall. In this case the VAZM-2U unit calculates a correction command for the ore flow rate regulator, and this way the overload condition is overcome while the ore feed rate returns to the initial value. The VAZM-2U unit can also help reach the maximum output of the overflow product from a spiral classifier avoiding overgrinding, with the finest material being monitored. The unit can also determine the underflow flow rate in the spiral classifier while adjusting this parameter within a given range of allowable values. The underflow flow rate is estimated with the help of an adaptive mathematical model, which can be utilized in closed-loop grinding circuits that include classifiers. The ore grinding control algorithms implemented in the VAZM-2U unit can be modified to be applicable for milling and flotation control.