Polyamines are a class of cationic polymers widely applied in mineral processing, ore beneficiation, and tailings water clarification. They serve as coagulants and flocculant aids, primarily to neutralize the negative surface charge of suspended solids and fine mineral particles, thereby improving solid–liquid separation, froth flotation performance, and recycling of process water.

In mineral processing circuits—especially those involving fine tailings, coal, bauxite, phosphate, iron ore, and nonferrous metals—polyamines are often used alone or in combination with anionic flocculants such as anionic polyacrylamide (PAM) to achieve optimal performance.

Below is a detailed explanation of the main kinds of polyamines used for mineral processing, their chemical nature, and application functions.

1. Linear Polyamines (Epi-DMA Type)

The most common polyamines used in mineral processing are linear epichlorohydrin–dimethylamine (Epi-DMA) polyamines. These are low- to medium-molecular-weight cationic polymers with strong charge density.

Chemical structure: Produced by the polycondensation of epichlorohydrin and dimethylamine. The reaction generates a quaternary ammonium polymer chain with strong positive charges distributed along its backbone.

Main characteristics:

• Strong cationic charge density (10–40% depending on synthesis ratio)

• Moderate molecular weight (around 10,000–500,000 Da)

• Soluble in water and stable across pH 4–9

• Clear to light yellow viscous liquid

Applications in mineral processing:

• Acts as a primary coagulant to neutralize negatively charged clay, silica, or fine mineral particles.

• Used to clarify process water from thickeners or tailings ponds by promoting fine-particle aggregation.

• Enhances solid–liquid separation efficiency in thickening, sedimentation, and filtration stages.

• Commonly combined with anionic polyacrylamide in a dual-flocculation system (polyamine as coagulant + PAM as flocculant).

• Applied in bauxite residue (red mud) clarification in alumina refineries, coal tailings dewatering, and phosphate beneficiation processes.

Typical commercial equivalents:

• SNF FlocAid 19 or 20 series, or Polyamine FL2949

• Kemira Superfloc C-573 or C-573P

• BASF Magnasol 590

• Ecolab/Nalco N-1000 series

• Accepta 2055 / 2057

2. Branched Polyamines (Epi-Amine Type)

Branched polyamines are produced by reacting epichlorohydrin with polyamines such as ethylenediamine (EDA) or diethylenetriamine (DETA). The resulting structure has multiple cationic sites per molecule and exhibits higher charge density than linear types.

Key properties:

• High cationic charge (up to 50%)

• Low viscosity but excellent charge neutralization ability

• Excellent coagulating power for ultrafine or colloidal particles

• Operates effectively in high-salinity or acidic slurries

Applications:

• Used in tailings clarification where ultrafine mineral slimes (e.g., kaolin, silicates, alumina fines) cause turbidity.

• Effective for phosphate and rare earth flotation water treatment.

• Serves as a pre-coagulant before the addition of anionic flocculants in high-solids thickeners.

• Provides rapid turbidity reduction and improves recovery of recycled process water for reuse in grinding or flotation circuits.

Examples:

• SNF FlocAid 2950 / 2949 series

• BASF Praestol 854CP (polyamine blend for mining water)

• Kemira Superfloc C-496

• NCP Polyamine 50% solution for coal, copper, and bauxite

3. Poly(DADMAC)-Modified Polyamines (Blended Coagulants)

Some mineral plants use polyamine–polyDADMAC blends, which combine the charge-neutralizing efficiency of polyDADMAC (polydiallyldimethylammonium chloride) with the bridging ability of polyamine. These blends are useful where both fine particle charge neutralization and partial flocculation are required.

Features:

• Enhanced coagulation power compared to polyamine alone

• Suitable for high-turbidity tailings or process water

• Lower polymer dose due to synergistic effect

• Excellent water clarity and faster sedimentation rate

Applications:

• Iron ore tailings clarification

• Bauxite residue treatment in alumina refineries (Bayer process)

• Copper and gold tailings thickening

• Gypsum slurry dewatering

Typical product examples:

• SNF FlocAid 5120 (polyamine/polyDADMAC blend)

• BASF Magnasol 590H

• Kemira Superfloc C-572 / C-573 dual cationic types

4. Polyamine–Epoxy Adducts (High-Performance Coagulants)

Advanced mineral processing systems—especially those with high colloidal silica or organic contamination—use modified polyamines such as epoxy–amine adducts. These are polyamines partially crosslinked with small amounts of epoxide compounds to increase molecular weight and improve bridging action.

Advantages:

• Broader performance range than conventional coagulants

• High efficiency even in low turbidity waters (<50 NTU)

• Stable at high temperatures (up to 60 °C) and extreme pH values

• Enhanced floc strength and reduced polymer sludge

Applications:

• Used in fine tailings thickening for silica-rich ores (bauxite, gold, and rare earth)

• Applied in recycled process water treatment to reduce turbidity before reuse

• Employed in flotation water circuits to minimize contamination and improve froth stability control

Example products:

• SNF FlocAid 4000 series

• Ecolab NALMET polyamine-based clarifiers

• BASF Lurifix series (modified polyamines)

5. Selection Criteria for Polyamines in Mineral Processing

The choice of polyamine depends on the ore type, particle size, water chemistry, and pH conditions. Key parameters include:

6. Combined Use with Anionic Polyacrylamide

In most mineral plants, polyamine and anionic polyacrylamide (A-PAM) are used together:

• Step 1: Polyamine (coagulant) neutralizes particle charge.

• Step 2: Anionic PAM (flocculant) bridges neutralized particles into large, strong flocs.

This dual system significantly improves settling rate, overflow clarity, and underflow solids concentration compared with using either polymer alone.

Conclusion

The polyamines most effective for mineral processing are epichlorohydrin–amine polymers with medium molecular weight and high cationic charge, typically in liquid form (30–50 % active solids). These polymers—especially Epi-DMA and Epi-DETA types—excel at destabilizing fine mineral suspensions, clarifying tailings water, and enhancing thickener performance.

They are widely used in bauxite residue treatment, coal tailings dewatering, iron ore clarification, phosphate beneficiation, and gold tailings recycling. When properly selected and optimized, polyamines not only improve process efficiency and water recovery but also reduce chemical costs and environmental impact—making them indispensable reagents in modern mineral processing operations.