Kinetic Study and Numerical Validation of the Cyanide Neutralization Process Using Alkaline Chlorination

Abstract

In the recovery of precious metals from the mining industry, cyanide is the most used leaching agent due to its high efficiency. However, in some cases cyanide mining waste is dumped into bodies of water without a proper treatment, causing irreversible damage to the environment. Therefore, it is essential to have sustainable, efficient, and economic processes for the adequate treatment of cyanide toxic waste. This work presents a kinetic study of cyanide neutralization using an alkaline chlorination method on waste samples from silver leaching. Results presented demonstrate removal efficiencies of 99.7% at volumetric CN- with loading rates of about 2047 mg/l in a period of 75 h. Additionally, numerical simulation was validated considering the experimental results. For the simulation, fundamental parameters, such as mass balance, temperature and concentration, were considered to find kinetic global rate constants. The results obtained allowed to propose the design of a cyanide neutralization reactor.