Secco Polyacrylamide (PAM) is a highly effective polymeric flocculant widely used in coal washing wastewater treatment. It primarily removes suspended solids (SS) and colloidal particles through flocculation and sedimentation. 

Below is a comprehensive technical analysis:

1. Technical Principles

Flocculation Mechanism:

PAM’s active groups (—CONH₂) adsorb onto coal slurry particles, neutralizing surface charges and forming "bridges" to aggregate fine particles into larger flocs for rapid settling.

Anionic PAM (APAM): Suitable for alkaline wastewater (typical in coal washing) with negatively charged particles.

Non-ionic PAM (NPAM): Used for neutral or weakly acidic wastewater.

Cationic PAM (CPAM): Rarely used unless treating organic-rich or positively charged colloids.

Synergistic Effects:

Often combined with inorganic coagulants (e.g., PAC) for charge neutralization followed by PAM-enhanced flocculation.

2. Key Technical Parameters

Dosage:

Typically 0.1–10 mg/L, determined via jar tests. Excess PAM may cause re-stabilization or fragile flocs.

Dissolution & Preparation:

PAM must be dissolved to 0.1%–0.5% solution with ≥40 min stirring to avoid clumping.

Mixing Conditions:

Rapid mixing (200–300 rpm) for dispersion, followed by slow mixing (20–50 rpm) for floc growth.

3. Advantages

High Efficiency: Reduces settling time by >50%, achieving 90%–95% SS removal.

Sludge Dewatering: Forms dense flocs, improving filter press efficiency.

Cost-Effectiveness: Low chemical cost (~$0.05–0.12 per ton of water).

Environmental Safety: PAM is non-toxic, but residual acrylamide must be <0.05%.

4. Common Challenges & Solutions

Incorrect PAM Selection:

Conduct jar tests to optimize type (APAM/NPAM) and molecular weight (typically 8–12 million).

pH Sensitivity:

APAM works best at pH 7–10; acidic wastewater requires pH adjustment or NPAM.

Incomplete Dissolution:

Use dedicated dissolving equipment to prevent "fish eyes."

Floc Breakage:

Over-mixing or overdosing may destabilize flocs; optimize operational parameters.

5. Case Study

Coal Mine Wastewater Plant:

Influent: SS 2000–5000 mg/L, pH 8–9.

Process: PAC (50 mg/L) + APAM (2 mg/L).

Results: Effluent SS <50 mg/L; sludge moisture reduced from 98% to 75% after filtration.

6. Future Improvements

Composite Formulations: Combine PAM with bio-agents for COD/heavy metal removal.

Smart Dosing Systems: Real-time turbidity monitoring for dynamic dosing.

Green PAM Modifications: Starch-grafted PAM for better biodegradability.

Conclusion

PAM is a mature and cost-effective solution for coal washing wastewater, but performance depends on proper selection and process optimization. Integrated with pretreatment (screening) and post-treatment (filter pressing), it forms a complete treatment system.

If you have any further questions or requirements regarding polyacrylamide, please feel free to contact Secco at any time!