Application of PRAESTOL 2640 DK

PRAESTOL  2640 DK is a high-performance anionic polyacrylamide flocculant developed for demanding solid–liquid separation processes, especially where fine particles, high solids loading, and variable water chemistry create separation challenges. Owing to its optimized molecular weight and anionic charge density, PRAESTOL 2640 DK delivers strong particle bridging, rapid settling, and excellent clarification. It is widely applied in mining, mineral processing, alumina refining, wastewater treatment, and industrial sludge dewatering, where reliable and cost-effective separation is critical for operational efficiency.

1. Application in Alumina Refining (Bayer Process)

One of the most important applications of PRAESTOL 2640 DK is in the Bayer process for alumina production. During bauxite digestion, insoluble residues known as red mud must be separated from sodium aluminate liquor. Red mud particles are extremely fine and highly alkaline, making settling difficult.

PRAESTOL 2640 DK is used in:

• Primary settlers

• Secondary settlers

• Washer thickeners

The flocculant promotes aggregation of fine red mud particles into large, dense flocs, significantly increasing settling velocity. This leads to clearer overflow liquor, improved washing efficiency, and higher alumina recovery. At the same time, it helps achieve higher underflow density, reducing mud volume and improving residue handling.

2. Red Mud Washing and Caustic Recovery

In washer circuits, PRAESTOL 2640 DK plays a key role in improving caustic soda recovery. By forming strong and permeable flocs, it enables efficient displacement washing of entrained sodium aluminate and caustic liquor from red mud solids. This results in lower soda losses, reduced fresh caustic consumption, and improved overall refinery economics. Its stability under high pH and elevated temperatures ensures consistent performance throughout multi-stage washer systems.

3. Mining and Mineral Processing Applications

PRAESTOL 2640 DK is widely applied in mining and mineral processing, particularly for tailings thickening and clarification. Typical applications include:

• Thickening of mineral tailings

• Clarification of process water

• Concentrate dewatering

In these processes, the flocculant accelerates sedimentation of finely ground ores and gangue minerals, producing clear supernatant water suitable for reuse. Improved thickener performance allows higher throughput and better water recovery, which is increasingly important in water-scarce mining regions.

4. Industrial Wastewater Treatment

In industrial wastewater treatment, PRAESTOL 2640 DK is used as a primary or secondary flocculant to remove suspended solids, colloids, and inorganic particles. It is particularly effective in wastewater from:

• Metallurgical plants

• Chemical processing industries

• Power plants

• Cement and construction materials production

The product enhances floc formation following coagulation, leading to faster settling or flotation and reduced turbidity in treated effluent. This supports compliance with discharge regulations and improves the efficiency of downstream filtration or polishing steps.

5. Sludge Thickening and Dewatering

PRAESTOL 2640 DK is also applied in sludge thickening and dewatering systems. It improves sludge conditioning prior to mechanical dewatering using belt filter presses, centrifuges, or filter presses. By strengthening floc structure and releasing bound water, the flocculant enables higher cake solids and lower filtrate turbidity.

Benefits in sludge handling include:

• Reduced sludge volume

• Lower disposal costs

• Improved equipment performance

Its anionic nature makes it especially suitable for inorganic or mineral-rich sludges.

6. High-Rate Thickeners and Clarifiers

In modern high-rate and high-density thickeners, PRAESTOL 2640 DK supports stable operation at elevated feed rates. The flocculant ensures rapid aggregation and settling even under turbulent feedwell conditions. This allows plants to maximize capacity without sacrificing overflow clarity or underflow density.

7. Environmental and Water Recycling Benefits

By improving solid–liquid separation efficiency, PRAESTOL 2640 DK contributes to water conservation and environmental protection. Clearer overflow water can be recycled back into the process, reducing freshwater intake. Higher solids concentration in underflow minimizes the volume of waste slurry sent to disposal facilities, lowering environmental footprint and storage requirements.

8. Dosage and Application Method

PRAESTOL 2640 DK is supplied as a dry granular powder and is typically prepared as a dilute aqueous solution before dosing. Proper make-down, aging, and gentle mixing are essential to fully activate the polymer chains. Optimal dosage depends on solids concentration, particle size distribution, and process conditions, and is usually determined through laboratory testing and plant trials.