Achieving significant operational improvements in tailings handling requires a balanced approach that combines process optimization with an effective chemical solution. Kemira’s Superfloc® RH4821 rheology modifier flocculant helped this Brazilian bauxite producer stabilize its water treatment process, conserve water, and increase tailings-handling capacity.
Water use and tailings management constraints
Paragominas, a bauxite producer in northern Brazil, produces approximately 14 million metric tons of bauxite annually. The production process is water‑intensive, requiring around 28 million cubic meters of water each year. Operating in a region with limited water availability, the site must maximize water recycling across its operations. Despite these efforts, a significant share of water is still lost through the tailings stream.
The operation generates large volumes of wet tailings, which are initially stored in a dam to allow natural drying. Only after sufficient drying can the material be transported by truck to a landfill. This prolonged drying phase limits overall tailings-handling capacity and increases transportation and processing costs, underscoring a clear need for more efficient water-recovery and tailings-management solutions.
Working closely with Kemira, the Paragominas operations team took a structured, data‑driven approach to identify opportunities for process improvement. Together, the teams focused on understanding current performance, addressing operational constraints, and defining clear targets to support more efficient and stable tailings management.
Paragominas defined the following key performance indicators:
- Increase underflow solids to improve water recovery
- Lower underflow rheology to support easier handling and transport
- Increase thickener capacity to enable more efficient operation
- Reduce flocculant consumption while maintaining performance
- Improve overall process stability for consistent, reliable operation
A newly developed chemical solution tailored for industrial water treatment
Kemira conducted a series of laboratory evaluations to identify a flocculant better suited to Paragominas’ tailings-thickener requirements. The testing focused on improving underflow performance while supporting the site’s need for increased water recovery and stable operation.
Based on these assessments, Kemira’s newly developed Superfloc RH4821 emerged as the best‑performing solution and was selected for further evaluation in a full‑scale plant trial. Superfloc RH4821 is an anionic rheology modifier designed to enhance thickener performance by enabling higher underflow solids while maintaining favorable flow characteristics.
By improving rheology control at higher solids concentrations, Superfloc RH4821 supports more efficient thickener operation and maximizes water recovery—an essential requirement for Paragominas, where water availability is limited and effective water management is critical to sustainable production.
Trial Setup
- 7-month full-scale trial
- Tailings Thickener Line 1: Kemira Superfloc RH4821
- Tailings Thickener Line 2: Incumbent flocculant
Trial Quality Metrics
- Feed solids % and flow in cubic meters per hour (m³/h)
- Dry solids in tons/hour (t/h)
- Underflow solids %
- Flocculant dosage in grams/ton (g/t)
- Thickener torque
Results with higher underflow solids and lower dosage
The full-scale trial not only achieved Paragominas’ key performance indicators—it showcased a clear performance advantage.
By running one thickener with Superfloc RH4821 and the other with the incumbent flocculant, the team demonstrated a compelling, side-by-side comparison that highlighted RH4821’s standout operational performance.
Superfloc RH4821 consistently achieved higher underflow solids, with a larger share of data points meeting or exceeding the 33–35% target range. This exceptional performance was delivered at a lower average dosage of just 118 g/t—compared with 180 g/t for the incumbent flocculant—highlighting a significant gain in process efficiency.
Despite the increase in underflow solids, the rheology of the underflow material improved significantly. Superfloc RH4821 reduced the average rake torque to just 2.2% of maximum, a dramatic improvement over the 14.9% measured with the incumbent flocculant. This reduction confirms a decrease in underflow rheology, supporting more stable thickener performance and improved tailings handling, even at higher solids content.
Thickener Performance Summary
| Underflow solids & torque | Superfloc RH4821 % of time | Incumbent flocculant % of time |
| Above 35% Solids | 35% | 7% |
| Target 33-35% Solids | 52% | 56% |
| Below 33% Solids | 13% | 37% |
Conclusion: Measurable performance gains delivered by advanced water treatment chemicals
The trial clearly demonstrated that Superfloc RH4821 delivers measurable improvements in tailings thickening performance. By increasing underflow solids, the site achieved significant water savings, while drier tailings shortened the drying phase before off-site transport. Together, these gains enabled Paragominas to boost tailings handling capacity and improve overall operational efficiency.
By combining process optimization and advanced rheology control, Kemira’s solution improved thickener stability and addressed essential operational and sustainability challenges in tailings management.
Technical Achievements
- Underflow solids increased by 1-2% with a tendency toward 3%
- Lower underflow rheology, supporting easier handling and transport
- Flocculant consumption reduced by more than 35% (180 g/t to 118 g/t)
- Increased thickener throughput
- Increased tailings-handling capacity
- Enhanced process stability
Sustainability & Economic Benefits
- Predicted annual savings exceeding €350,000
- Eliminates the need to build new permanent tailing dams
- Reduces environmental liability from tailings management
- Cuts labor and annual costs associated with raising existing tailings dams
