Automatic control of free cyanide at Yvan-Vezina plant

For many years, the Yvan-Vezina gold plans has custom milled and processed different ore types that show different behaviour. Because of this cyanidat ion control is more complex than for a typical milling operation. In 1992, a Cyancor(TM) on-line "free cyanide" analyzer was installed to monitor and optimize cyanidation. This implementation significantly reduced cyanide con sumption for the overall cyanidation process, In order to further reduce cy anide costs, an automatic control strategy has been implemented to decrease fluctuations of "free cyanide" from their set points. This paper outlines the major steps of the project: process control audit, control strategy development, implementation and running-in period. Control strategy features include data filtering modules, adaptive PID algorithm, and set points management modules. Finally the strategy efficiency is illus trated with load-disturbance responses.