Influencing factors on the efficiency of tailings slurry thickening with sodium polyacrylate superabsorbent polymers

This study proposes an alternative method for dewatering mine tailings slurries using superabsorbent polymers (SAPs), leveraging their exceptional water absorption and retention properties. The factors influencing the efficiency of this dewatering process are systematically evaluated and discussed. Experimental investigations were conducted using two types of SAPs (SAP1 and SAP2, differentiated by varying concentrations of the same adsorbed Na cation) to assess their dewatering potential on four distinct mine tailings slurries under two addition modes (direct and indirect). The initial solid mass concentrations (Cw_initial) tested were 40% and 50%, with SAP dosages (DvSAP) ranging from 6 to 29 kg dry SAP per cubic meter of tailings slurry. The findings indicate a negligible difference in absorbency between SAP1 and SAP2. Furthermore, final solid mass concentrations (Cw_final) of 70–82% were achieved with SAP dosages between 10 and 29 kg/m³. However, the efficiency of the SAP-mediated dewatering process was influenced by several factors, including DvSAP, the mineralogical and physical characteristics of the tailings’ slurry, the initial solid mass concentration (Cw_initial), the porewater chemistry and geochemistry, the SAP residence time (RT), and the addition mode (direct or indirect).