Improved dewatering of clay rich mineral dispersions using recyclable superabsorbent polymers
Chemical Engineering Research and Design
School of Engineering
Despite the achievement of fast sedimentation rates in gravity-driven thickeners using flocculants, characteristically low to mediocre sediment consolidation with undesirably high water content (e.g., > 87 vol.%) is observed for clay-rich suspensions. The present work investigates the application of unconventional, recyclable sodium polyacrylate superabsorbent (SAB) polymer to dewater fine, hydrophilic Na-montmorillonite swelling clay and saprolitic nickel (Ni) laterite slurries for dramatic improvement. The results indicated that SAB application to concentrated and dilute slurries led to remarkably high water recoveries, unattainable via flocculation and thickening. In most cases, >95% of the water absorption occurred within 3 h. The extent of SAB water absorption was greater for saprolitic slurries than for Na-montmorillonite slurries, regardless of dispersion conditions. Consequently, 66 − 85 wt.% of the water in the slurry was recovered for recycle, exemplifying the efficacy and beneficial use of the superabsorbent in hydrophilic mineral slurry dewatering applications.