Polyamine is a cationic polymer that works mainly through charge neutralization and particle agglomeration, and it is widely used in water treatment and mineral processing (mining). Below is a clear, industry-oriented explanation tailored to how polyamine is actually applied in practice.

1. What Is Polyamine?

Polyamine is a low to medium molecular weight cationic polymer produced by the polymerization of amines (e.g., epichlorohydrin–dimethylamine type).
Unlike polyacrylamide flocculants, polyamine acts primarily as a coagulant rather than a long-chain bridging flocculant.

Key characteristics

• Strong positive charge density

• Relatively short polymer chains

• Rapid reaction with negatively charged particles

• Effective over a wide pH range

2. How Polyamine Works – Core Mechanisms

(1) Charge Neutralization (Primary Mechanism)

Most suspended solids in water and mineral slurries carry a negative surface charge (e.g., clay, silica, iron oxides, red mud, tailings fines).

Polyamine works by:

• Adsorbing onto negatively charged particle surfaces

• Neutralizing or reducing the surface charge (zeta potential)

• Eliminating electrostatic repulsion between particles

Once charge repulsion is removed, particles can collide and stick together.

(2)Patch Coagulation

Because polyamine has:

• High charge density

• Short molecular chains

It creates localized positively charged “patches” on particle surfaces.
These patches attract negatively charged areas on nearby particles, forming micro-aggregates.

This is different from long-chain bridging seen with polyacrylamide.

(3) Micro-Floc Formation (Pre-Flocculation)

Polyamine typically forms:

• Small, dense, fast-settling micro-flocs

• Strong initial agglomerates that can act as seeds

For this reason, polyamine is often used before a flocculant such as:

• Anionic polyacrylamide

• High-MW nonionic PAM

3. Role of Polyamine in Water Treatment

（1） Raw Water Clarification

Polyamine is used to:

• Destabilize colloids

• Remove turbidity

• Improve sedimentation and filtration

Common water sources

• River water

• Surface water

• Industrial intake water

It replaces or supplements inorganic coagulants like alum or ferric salts.

（2） Industrial Wastewater Treatment

Polyamine is highly effective for:

• Oily wastewater

• High-turbidity industrial effluents

• Textile, steel, chemical, and refinery wastewater

Functions

• Oil droplet destabilization

• Fine solids removal

• COD and TSS reduction

（3）Sludge Conditioning & Dewatering

Polyamine:

• Neutralizes negatively charged sludge solids

• Improves sludge cake formation

• Reduces polymer consumption when combined with PAM

Often used as:

• A primary coagulant

• Or a charge control agent before cationic PAM

4. Role of Polyamine in Mining & Mineral Processing

4.1 Tailings Thickening and Clarification

Mining slurries contain:

• Fine clay particles

• Negatively charged mineral fines

• Ultrafine silica

Polyamine helps by:

• Rapidly destabilizing fines

• Promoting initial agglomeration

• Improving overflow clarity

It is commonly used:

• As a coagulant aid

• Ahead of anionic polyacrylamide flocculants

4.2 Red Mud and Alumina Processing (Bayer Process)

In alumina refineries, polyamine is applied to:

• Neutralize fine red mud particles

• Improve settling rate

• Enhance mud compaction

• Increase process liquor recovery

Polyamine works well under:

• High alkalinity

• High solids concentration

4.3 Mineral Beneficiation & Process Water Recovery

Polyamine is used in:

• Thickener feed conditioning

• Clarifier overflow polishing

• Recycled process water treatment

Its fast action improves:

• Water reuse efficiency

• Thickener stability

• Downstream flocculant performance

5. Polyamine vs Polyacrylamide – Key Differences

6. Why Polyamine Is Often Used Together with PAM

In both water treatment and mining, the best performance is often achieved by:

1. Polyamine first
   – Neutralizes charge and destabilizes particles

2. Polyacrylamide second
   – Builds large, settleable flocs via bridging

This combination:

• Reduces total chemical cost

• Improves settling rate

• Produces clearer overflow

• Enhances dewatering efficiency

7. Summary

Polyamine works in water treatment and mining by:

• Neutralizing negatively charged particles

• Destabilizing colloids and fine solids

• Forming micro-flocs rapidly

• Acting as an effective coagulant or coagulant aid