Hengfeng Flocculant A1545 Stabilizes Copper Tailings Thickening Operation
A medium-to-large copper concentrator recently optimized its tailings thickening circuit to improve solid-liquid separation efficiency, increase water recovery, and raise underflow density. Shortly after changes in ore characteristics (finer grind and higher clay content), the high-rate thickener experienced slow settling, cloudy overflow, fluctuating underflow density, and occasional rake torque spikes.
By introducing Hengfeng Anionic Flocculant A1545 and implementing targeted process adjustments, the plant restored stable thickener performance and achieved continuous, high-efficiency operation.
Site Overview
Industry: Copper flotation / concentrator
Tailings throughput: approximately 8,000–12,000 t/day (dry solids basis)
Typical feed solids concentration to thickener: 12–18%
Wastewater / slurry characteristics:
Fine particles (significant -45 μm fraction), moderate clay content, residual flotation reagents, pH 8.5–10.5, high suspended solids.
Thickener configuration:
One high-rate thickeners
Anionic polymer previously prepared at 0.1–0.15% concentration
Designed underflow density target: ≥60% solids
Overflow clarity target: <150–200 mg/L SS
Initial Issues
Settling rate was insufficient; clear water interface rose slowly.
Overflow SS frequently exceeded 300–500 mg/L.
Underflow density fluctuated between 52–58% solids.
Higher polymer consumption (often >50 g/t) was required to maintain performance, yet results remained inconsistent.
Occasional bed instability and elevated rake torque increased operational risk.
Problem Analysis
On-site evaluation identified several contributing factors:
1.Inadequate floc strength and size
The previous polymer had lower molecular weight and suboptimal charge density for the current finer, more clay-bearing tailings. Formed flocs were relatively small and shear-sensitive, limiting settling velocity and bed compaction.
2.Sub-optimal dosage and preparation
Semi-automatic dosing led to fluctuations. Solution concentration and aging time were not strictly controlled, reducing active polymer efficiency.
3.Feed variation and dilution effects
Changes in ore hardness and flotation conditions altered particle size distribution and surface chemistry, reducing the effectiveness of the existing flocculant grade.
4.Insufficient bridging capacity
Residual dispersants and finer colloids required a higher-molecular-weight anionic polymer with balanced charge density to achieve strong particle bridging and robust flocs suitable for high-rate thickening.
Technical Solution
Optimized Chemical Strategy
Hengfeng introduced Anionic Flocculant A1545 which optimized for copper and base-metal tailings.
Solution preparation: 0.1–0.15% concentration with adequate aging (≥45–60 minutes).
Dosage range (dry basis): 25–40 g/t of dry solids, typically stabilized at 28–35 g/t after optimization (well within the common industrial range of 20–50 g/t for copper tailings).
Dynamic adjustment based on feed solids, settling rate observation, overflow clarity, and underflow density.
A1545’s higher molecular weight and optimized charge density produced larger, denser, and more shear-resistant flocs, significantly improving settling velocity and bed compaction.
Dosing Point Optimization
Polymer solution was injected into the thickener feed well (or diluted feed line) to ensure rapid and uniform distribution with controlled mixing energy, maximizing floc formation before the slurry entered the settling zone.
Operator Training & Standardization
On-site training covered:
Correct solution preparation and aging procedures
Visual assessment of floc size and settling behavior
Routine monitoring of overflow clarity, bed level, and underflow density
Standardized dosage adjustment protocols linked to feed changes
These measures eliminated inconsistent operation and ensured reproducible chemical control.
Performance Results
After process optimization and continuous monitoring:
Settling rate improved markedly; clear supernatant formed rapidly.
Overflow suspended solids consistently reduced to <80–120 mg/L.
Underflow density stabilized at 62–68% solids (meeting or exceeding design targets).
Polymer dosage reduced and stabilized in the 28–35 g/t range while delivering better performance.
Rake torque remained stable; bed level control became more predictable.
Water recovery improved, supporting higher circulating water quality and reduced fresh-water demand.
Overall thickener capacity and operational reliability increased, supporting uninterrupted production.
Project Outcome
Through selection of the appropriate high-performance anionic grade (A1545), precise dosage control, optimized addition points, and operator training, Hengfeng converted an unstable copper tailings thickening circuit into a reliable, high-efficiency solid-liquid separation process.
