Polyamine is a water-soluble cationic polymer widely used as a coagulant and charge-neutralization agent in water treatment, mining, alumina refining, and various industrial processes.
Polyamine is a water-soluble cationic polymer widely used as a coagulant and charge-neutralization agent in water treatment, mining, alumina refining, and various industrial processes. Polyamine products are typically manufactured by polymerizing amine-based monomers, resulting in polymers with high cationic charge density and low to medium molecular weight.
Because most suspended solids in water and process slurries carry a negative surface charge, polyamine is highly effective at destabilizing these particles. Compared with inorganic coagulants such as aluminum sulfate or ferric chloride, polyamine offers faster reaction speed, lower dosage, reduced sludge production, and broader operational flexibility.
The primary mechanism of polyamine is charge neutralization. In untreated systems, negatively charged particles repel each other and remain dispersed. When polyamine is added:
Positive charges neutralize negative particle surfaces
Electrostatic repulsion is eliminated
Fine particles collide and agglomerate
Destabilized particles become easier to flocculate or settle
Polyamine does not rely on long polymer chains for bridging like polyacrylamide. Instead, it prepares the system for efficient flocculation by rapidly destabilizing colloidal and fine particles. For this reason, polyamine is often used ahead of anionic or nonionic polyacrylamide flocculants.
In municipal drinking water treatment plants, polyamine is widely used as a primary coagulant or coagulant aid. It is particularly effective for removing:
Turbidity
Colloidal particles
Natural organic matter
Polyamine improves floc formation and sedimentation efficiency, resulting in clearer clarified water and longer filter run times. Its low metal content helps reduce residual aluminum or iron in treated water, making polyamine suitable for potable water applications when compliant grades are used.
Polyamine is extensively applied in industrial wastewater treatment, where effluents often contain complex mixtures of suspended solids, oils, pigments, and chemical residues.
Typical industries include:
Chemical manufacturing
Steel and metallurgy
Pulp and paper
Textile and dyeing
Power generation
In these systems, polyamine enhances solid–liquid separation, reduces total suspended solids (TSS), and improves downstream treatment performance. Its fast action makes it ideal for high-flow or space-limited treatment systems.
Sludge treatment is one of the most important application areas for polyamine. Sludge particles often carry strong negative charges that trap water and resist dewatering.
Polyamine improves sludge conditioning by:
Neutralizing sludge particle charges
Releasing bound water
Improving floc structure
Enhancing dewatering efficiency
When used alone or in combination with polyacrylamide, polyamine increases cake solids content and reduces sludge volume, leading to lower transportation and disposal costs.
Mining operations generate large volumes of water contaminated with fine mineral particles such as clays, silica, and metal oxides. Polyamine is widely used in process water clarification systems to rapidly destabilize these fines.
Benefits include:
Faster clarification
Improved overflow clarity
Stable operation under variable pH and salinity
Enhanced water recycling
Clean recycled water improves grinding, flotation, and equipment reliability.
In tailings thickeners, fine particles often remain suspended even when flocculants are applied. Polyamine acts as a pre-coagulant, improving the performance of high-molecular-weight flocculants.
In tailings applications, polyamine:
Improves settling rate
Increases underflow density
Reduces flocculant consumption
Enhances overflow water quality
This is particularly important in modern mining operations focused on water conservation and environmental compliance.
In alumina refineries using the Bayer process, polyamine plays a key role in red mud settling, washing, and clarification. Red mud particles are extremely fine and highly negatively charged, making them difficult to settle.
Polyamine improves:
Red mud settling speed
Clarification efficiency
Caustic soda recovery
Stability of washers and thickeners
Polyamine is commonly used together with anionic polyacrylamide to achieve optimal performance in high-alkalinity conditions.
Polyamine is also applied in:
Oilfield produced water treatment
Refinery wastewater clarification
Coal washing and preparation plants
In these applications, polyamine removes suspended solids and emulsified particles, improving water reuse and reducing environmental discharge risks.
Typical polyamine dosages range from 10 to 200 g per ton of dry solids, depending on water chemistry, solids concentration, and process conditions. Polyamine is usually applied as a diluted aqueous solution and requires good initial mixing for effective charge neutralization.
Jar testing and plant trials are strongly recommended to determine the optimal dosage and combination with flocculants.
Key advantages of polyamine include:
Very fast coagulation speed
High efficiency at low dosages
Wide pH operating range
Reduced sludge generation
Excellent compatibility with polyacrylamide
Improved system stability
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