Automating cyanide measurement & control in highly variable complex copper gold ores by applying a modified potentiometric titration determination

Newmont’s Yanacocha operation in Peru presented an especially challenging environment for reliable cyanide measurement and control, processing 3 semi-distinct complex ore types with feed Cu ranging from below 250ppm (as CuCN) to more than 5000ppm, and feed S ranging from low to 5%, resulting in cyanide consumption from as low as 1.5 kg/t to as high as 3.1 kg/t, and gold recovery ranging from approximately 57% to about 78 % (average plant performance based on the type of ore). A literature search by the authors to identify a method for accurate cyanide determination that was also suitable for automation settled on the work of Breuer et al (2011) as a basis. Early challenges in adapting the laboratory technique for the ‘real solutions’ and the range of variability experienced in the plant are discussed, as are other operational challenges due to the complex and changing solution chemistry.