Hardness and chloride removal in dewatering system: Modeling and optimization of electrochemical reaction

The electrocoagulation (EC) process is a novel approach in the mining industry, especially to recycle water in the dewatering system of a mineral processing plant. In this research, the electrocoagulation process was studied to remove the hardness and chloride ions from concentrate thickener overflow water under different operating conditions: retention time (۵–۱۵ min), initial pH (۴–۱۰), current density (۴۱.۶–۱۶۶.۶ A/m۲) and electrode type (Fe, Fe-Al, Al). Four factors with three levels with the D-optimal response surface design were applied for optimization. As a result, the optimal situation for the electrocoagulation process was characterized by a retention time of ۱۵ min, initial pH of ۹.۰۸, the current density of ۱۳۹.۵۹ A/m۲, and electrode type Fe-Al. In this situation, the maximum removal efficiency of hardness (۶۰.۱۱%) and chloride (۹۸.۳۸%) were yielded with a desirability value of ۰.۹۸۹. These results illustrated the effectiveness of the EC process as an influence method for the removal of hardness and chloride in terms of separation.