Grant: CCI Applied Research and Development Grants

In general, the mining industry is known for its extensive use of explosives, as well as the use of cyanides for the extraction of precious metals, such as gold and silver. These operations generate toxic nitrogen compounds, including residual cyanides (CN-, 100-500 ppm), cyanates (OCN-, 40-50 ppm), thiocyanates (SCN-, 300-400 ppm), and ammoniacal nitrogen (N-NH3, 20-50 ppm), which end up in the final effluent. Discharge requirements are expected to significantly impact wastewater management within the mining industry. In Canada, metal and diamond mines are now required to meet a maximum authorized monthly mean concentration of 0.5 mg of N-NH3/L. Moreover, to comply with the toxicity requirements imposed by Directive 019 for CN- (average monthly total cyanide must be less than 1 ppm), decent management and effective treatment are required. This proposed project is seen as a continuity for the SEP funded by NSERC (560848–20 RDA). The results of the prior project illustrated that ozonation (among the other processes, such as UV irradiation, ultrasonic treatment, etc.) is the most effective method and is the fast treatment option for the detoxification of gold cyanidation effluents. In the current proposal, the CTRI collaborates with Kairospace Technologies and Eldorado Gold, to integrate an innovative catalytic ozonation approach for N-based compounds treatment in mine effluents. The use of catalysts in catalytic ozonation can significantly improve the efficiency of the process and reduce the amount of ozone required. Catalysts can enhance the formation of reactive oxygen species, which are responsible for the oxidation of nitrogen-based pollutants. The performance of catalytic ozonation can be influenced by a number of factors, including the pH and temperature, the concentration of pollutants, ozone dosage, ozone bubble sizes, and the amount of catalyst. The main goal of this project is to propose new lines of investigation for research to develop a process for CN-, SCN- and NH3-NH4+ removal from various mining effluents by ozone oxidation in MgO catalytic bed in continuous mode. Optimizing the mentioned factors is critical to achieving high levels of removal efficiency. specific objectives will be proposed: (1) Characterization of the effluents; (2) Setting up a prototype of the system; (3) Investigation of the effective operational parameters and optimization, (4) and general economical assessment and final report preparation.