Kinetics of the oxidation of cyanide with ozone in gold mill wastewaters

The oxidation of cyanide by ozone was studied using a bubble column reactor. Operating parameters such as pH, temperature, ozone dosage rate, gas flow rate and cyanide concentrations were explored. The results on synthetic solutions showed that the rate of the cyanide oxidation may be described by an equation which is of first order with respect to ozone and zero order with respect to cyanide. The rate constant obtained for the reaction is in the order of 1 x 10(-5) mole/l s. The stoichiometry of the reaction consists of the oxidation of one mole of cyanide with one mole of ozone. Values of the factor of enhancement (E) of 1.011 indicate the reaction may be classified as a diffusion controlled process. The effect of the temperature was explored. The oxidation of effluents of industrial cyanidation processes was also studied. The results showed the rate of the oxidation is enhanced by the presence of copper in the industrial solutions.