AN AMPEROMETRIC INSTRUMENT FOR THE DETERMINATION OF CYANIDE ON GOLD PLANTS

A method is described for the determination of cyanide in gold slurrie s based on amperometry. The measured current is proportional to the co ncentration of cyanide, and is not affected by pH or by the concentrat ion of oxygen in solution. It is also unaffected by other ions that ma y be present in gold-leaching solutions, including sulphide, thiocyana te, and thiosulphate. The current depends on the temperature, and an a ctivation energy of 17,9 kJ/mol was determined. Since the current is c ontrolled by the mass transfer of cyanide to the anode it depends on t he conditions of agitation. In tests on an operational gold plant, slu rry was pumped directly from the top of the leaching tank, through the measuring cell, and back into the tank. The results indicate that the instrument is a promising alternative to the instruments currently av ailable. The readings from the instrument remained in calibration for at least two days showing that the instrument would need to be re-cali brated by the operating staff at regular periods.