INCO laboratories developed a process to eliminate cyanide from milling waste using sulphur dioxide, air and lime. The chemistry of the process was outlined, including the effect of pH. The applicability of the process is high, but the conditions of treatment and control strategy vary with each case. Some types of treatment were outlined. This experimental process was implemented at the Scottie Gold Mines and the McBean Mine. The data collected, including cost effectiveness, was discussed.