Red Sea Phosphate Mine — PAM Flocculant for Tailings Dewatering
High-molecular-weight anionic PAM achieved 90% solids capture in phosphate tailings, enabling water recycling in an arid environment.
Challenge
A phosphate mining and beneficiation operation near the Red Sea coast was struggling with slow tailings settling rates in its thickener circuit. The high clay content (> 30% < 2 µm particles) and elevated phosphate levels created stable colloidal suspensions that resisted natural settling, resulting in excessive freshwater consumption and expanding tailings storage requirements.
Solution
CHIMI ART's mining applications team conducted bench-scale thickener tests with multiple anionic PAM grades. The selected flocculant — a high-molecular-weight (18 million Da), medium-charge-density anionic polyacrylamide — was optimized at a dose of 25 g/tonne of dry solids. A two-point addition system was designed: 70% of the dose at the thickener feedwell and 30% at the feed pipe.
Results
- 90% solids capture in underflow, with overflow clarity < 100 mg/L TSS
- 75% of process water recovered and recycled, reducing freshwater intake by 4,000 m³/day
- Thickener underflow density increased from 35% to 52% solids, reducing tailings storage volume by 30%