CONTROL OF CYANIDATION AT YVAN-VEZINA PLANT

The Yvan Vezina mill, with a capacity of 1375 t/d, processes a variety of ores from the Beauchemin, Silidor and Mouska mines as well as a py rite concentrate from the Beliveau mine. These feeds were shown to dif fer widely in mineralogy, gold content and behaviour during cyanidatio n. This paper describes a project which was undertaken in 1991 to impr ove the control of cyanide during gold leaching. The performance of th e online analyzer, modifications in circuit parameters and the repercu ssions observed are discussed. Modification in the leaching practice b y addition of lead nitrate and close control of cyanide addition reduc ed cyanide consumption by 40%. These modifications in leaching practic e in combination with a decrease in the particle size of the ore incre ased gold recovery by 1.7% with an average gold recovery rate of 95.7% .