PRAESTOL® 2515 is an anionic polyacrylamide flocculant with high molecular weight and a moderate anionic charge density, developed for efficient solid–liquid separation in a wide range of industrial processes. Its molecular structure allows strong particle bridging and rapid floc formation, making PRAESTOL® 2515 particularly effective for the treatment of fine mineral suspensions, inorganic slurries, clays, and metal hydroxide solids, especially under neutral to alkaline pH conditions. Due to its balanced performance, PRAESTOL® 2515 is widely used in mining, mineral processing, alumina refining, coal preparation, and industrial wastewater treatment.

1. Flocculation Mechanism and Product Characteristics

PRAESTOL® 2515 works mainly through a polymer-bridging flocculation mechanism. The long polymer chains adsorb onto multiple particle surfaces, linking them together into large, dense flocs that settle rapidly under gravity. The anionic functional groups enhance adsorption on positively charged mineral surfaces or metal hydroxides formed after coagulation.

Key characteristics of PRAESTOL® 2515 include:

• Rapid floc formation and settling

• Strong, shear-resistant flocs

• High overflow clarity

• Good compatibility with inorganic coagulants

• Stable performance across a broad pH range

These features allow PRAESTOL® 2515 to perform reliably in high-rate and high-solids thickening systems.

2. Application in Mining and Mineral Processing

2.1 Tailings Thickening and Disposal

One of the primary applications of PRAESTOL® 2515 is in tailings thickening for mining operations such as:

• Copper and base-metal mining

• Gold and precious-metal processing

• Iron ore beneficiation

• Phosphate and industrial mineral processing

In tailings circuits, fine particles generated during grinding and flotation remain suspended and require efficient separation before discharge. PRAESTOL® 2515 significantly improves settling performance in:

• Conventional thickeners

• High-rate thickeners

• High-density and paste thickeners

Its use results in higher underflow solids concentration, improved water recovery, reduced tailings volume, and lower costs associated with tailings storage and water management.

2.2 Process Water Clarification

PRAESTOL® 2515 is also widely used for clarifying recycled process water in mineral processing plants. Efficient removal of suspended solids reduces turbidity and helps prevent scaling, abrasion, and fouling of downstream equipment. Cleaner process water improves grinding efficiency, flotation selectivity, and overall metallurgical performance.

3. Application in Coal Preparation and Washing

In coal washing plants, PRAESTOL® 2515 is applied in black-water clarification systems to flocculate fine coal particles and clay minerals. It is effective in:

• Coal tailings thickeners

• Clarifiers and settling tanks

• Water recovery circuits

The use of PRAESTOL® 2515 enhances settling rates and overflow clarity, enabling high levels of water reuse and reduced freshwater intake. This supports both operational efficiency and environmental compliance.

4. Application in Alumina Refining (Bayer Process)

PRAESTOL® 2515 is suitable for use in alumina refineries, particularly in red mud settling and washing circuits. During the Bayer process, bauxite digestion produces highly alkaline slurries containing fine red mud particles that must be efficiently separated from sodium aluminate liquor.

When dosed into:

• Primary settlers

• Mud washers

• Counter-current decantation (CCD) circuits

PRAESTOL® 2515 provides:

• Faster red mud settling rates

• Improved liquor clarity

• Enhanced recovery of caustic soda

• Reduced solids carryover

Its chemical stability under high pH and elevated temperature conditions ensures consistent flocculation performance in continuous alumina production.

5. Application in Industrial Water and Wastewater Treatment

5.1 Primary and Secondary Clarification

PRAESTOL® 2515 is widely used in industrial wastewater treatment plants treating:

• Mining and mineral-processing effluents

• Metallurgical wastewater

• Chemical industry process water

• Power plant ash pond and cooling water blowdown

Used as a primary flocculant or as a co-flocculant with inorganic coagulants such as ferric chloride or alum, PRAESTOL® 2515 enhances floc size and settling velocity, resulting in improved suspended solids removal and reduced sludge volume.

5.2 Sludge Thickening and Dewatering

PRAESTOL® 2515 is effective for sludge conditioning prior to mechanical dewatering. It improves the performance of:

• Gravity sludge thickeners

• Belt filter presses

• Vacuum filters

• Centrifuges

The polymer forms strong, well-structured flocs that release water easily, leading to higher cake solids and reduced sludge handling and disposal costs.

6. Preparation, Dosage, and Handling

PRAESTOL® 2515 is typically supplied as a dry, free-flowing granular powder. Proper preparation is essential:

• Typical make-down concentration: 0.1–0.3%

• Hydration time: 45–60 minutes

• Gentle agitation to avoid polymer degradation

Dosage generally ranges from 5 to 80 g per tonne of dry solids, depending on slurry characteristics and process conditions.

7. Summary and Key Benefits

In summary, PRAESTOL® 2515 offers:

• Efficient solid–liquid separation

• Rapid settling and excellent overflow clarity

• High underflow density and improved water recovery

• Reliable performance in neutral to alkaline systems

• Reduced operating and environmental management costs

Because of its versatility and consistent performance, PRAESTOL® 2515 is a preferred flocculant in mining, coal preparation, alumina refining, and industrial water-treatment applications.