DISTRIBUTED CONTROL AT THE KIDD CREEK GRINDING PLANT .1. CONTROL STRATEGY DESIGN

This two-part paper summarizes the design and implementation of a dist ributed PI based control strategy installed at the B grinding circuit, at the Kidd Creek Division of Falconbridge Ltd. Part I details the de sign of the control strategy using a grinding circuit dynamic simulato r (DYNAFRAG). The first step consisted of sampling campaigns and data processing to calibrate DYNAFRAG. Then, several control alternatives w ere designed and tested with the simulator. The main feature of these strategies is their ability to regulate or keep within an upper and lo wer limit five output variables (circulating load, rod mill density, c yclone feed and overflow densities and pump box level) with only three manipulated variables (rod mill water, pump box water and rod mill to nnage). By simulation on DYNAFRAG, it was possible to discriminate amo ng several control structures. The preferred control strategy uses a s aturation algorithm, which allows the adequate regulation of two measu red variables with only one actuator. Controllers located in interacti ng loops are appropriately tuned, taking into account the existing pro cess coupling. Part II will present the implementation of the selected control strategy.