Removal performance of silica and solid colloidal particles from chalcopyrite bioleaching solution: Effect of coagulant (Magnafloc set #1597) for predicting an effective solvent extraction

Silicon dioxide is a compound containing two of the most abundant elements in Earth’s crust. One of the main obstacles for upright solvent extraction in a copper (bio)-hydrometallurgical production chain relates to the high silica content and solid colloidal particles in the pregnant leach solution (PLS) during the treatment chain. This study assesses by way of laboratory tests the removal performance of silica and fine colloidal particles in the bioleachate solution. Their concentration requirement at solvent extraction stage could not exceed 500 ppm and 75 ppm respectively. The contact time and three ratios (coagulant/PLS): 1/2; 1/1 and 1/3 settled. The removal method from coagulation with Magnafloc (set #1597) was performed by varying its concentration in contact with the bioleachate solution. The coagulation tests consisted of finding optimal conditions with the coagulant from 0.50 to 1000 ppm, while outcomes related to the interaction of bioleached solution with coagulant consisted of the search for the optimal ratio (volume ratio). From the above, the outcomes of coagulation tests revealed a removal optimisation of silica and solid colloidal particles from bioleachate solution, which has to be greater than 200 ppm, either 300 ppm and up, keeping a volume ratio of 1/1, for a recovery rate of 68% and 58% respectively for a removal efficiency of SiO₂ and solids in suspension. A reduction of the phase separation time in aqueous continuity was observed from 230 to 148 seconds. It can be noted from the results mentioned above that the removal method will promote an effective copper solvent extraction stage, affecting the operating cost and greener environment with the possibility for recycling the organic wastes.