Superabsorbent recycling for process water recovery

Abstract The high process water content of many mineral tailings warrants development and application of new and cost-effective dewatering methods, involving high-capacity and regenerable water-absorbing polymers. The stimuli responsive nature of Superabsorbent (SAB) polymers enables them to release absorbed water upon changing process conditions (e.g., temperature and pH), allowing superabsorbent polymers recycling towards improving dewatering process economics. To understand the effect of process conditions and ore type coupled with cost effectiveness of superabsorbent dewatering system, this study investigates recovery of the absorbed water by pH induced superabsorbent regeneration. The superabsorbent, sodium polyacrylate, absorbed water from hydrophilic saprolitic laterite and hydrophobic chalcopyrite slurries prior to the investigations. Specifically, the effect of pH of absorbed water, SAB dosage and acid type (CH3COOH, HCl) and dosage on the SAB's water recovery behaviour was studied. The SAB dosage of 2 g/100 g slurry and HCl dosage of 2 g/100 g absorbed water were conducive for maximum water recovery (~95%) from both slurries while their pH and mineralogy had no noticeable effect on the SAB dewatering process. The overall performance, based of maximum recovered water, of CH3COOH in the SAB dewatering system was lower than HCl, however, relatively higher water recovery (~70 wt.%) was observed for Ch3COOH under slightly acidic solution conditions (~ pH 4) compared with HCl (~45 wt.% water recovery). The findings aid to the development of improved, cost-effective management of both, hydrophobic and hydrophilic waste tailings.