Optimization of coagulation-flocculation process for treatment of a colloidal suspension containing dolomite/clay/borax

This study statistically investigated the turbidity removal of a dolomite/clay/borax-containing colloidal suspension that had a high degree of stability. During the destabilization experiments, the mixing intensity, the dosage of the coagulant and the flocculant was tested at fixed pH 9.40 due to the buffering property of dissolved borax. Then, the performance of the coagulation/flocculation process was evaluated with Response Surface Methodology (RSM) by using Box-Behnken Design. For the collected experimental data set, the different models were formed. However, the logarithmically transformed model (R2: 99.75%; Adj-R2: 99.30%) was selected as the most capable one for the physicochemical process. By using this enhanced statistical model, the optimum turbidity removal was acquired with the help of the design variables as follows: the mixing intensity of 265.138 s− 1, calcium chloride dosage of 305.585 mg/L and the flocculant dosage of 218.619 g/ton-solid. Based on this result, it can be concluded that the treatment of the tailings of borax concentrators can be feasible if the physical and the chemical parameters of the solid/liquid separation process are properly implemented all together.