Coal washing plants in Australia, Indonesia, and South Africa have one thing in common: they all waste money on water. A 1,000 ton/day plant consumes 3,000 m³ of water daily. Without PAM-based recycling, that water gets discharged (regulatory violation) or replaced with fresh water ($3,000/day). We have helped plants in Queensland and Kalimantan cut water costs by over $800,000/year. Here is exactly what we use and how.
PAM Selection by Coal Type
| Coal Type | Particle Size | APAM Grade | Dosage | Settling Time |
|---|---|---|---|---|
| Thermal (bituminous) | 50-500 µm | 12-18M MW | 3-8 ppm | 30-60 min |
| Coking (anthracite) | 20-200 µm | 15-25M MW | 5-15 ppm | 1-3 hours |
| Lignite (brown coal) | 100-1000 µm | 10-15M MW | 2-5 ppm | 20-40 min |
Why Anionic PAM — Not Cationic
Coal particles are negatively charged. Cationic PAM should work better in theory. In practice, APAM outperforms CPAM in coal washing every time. Here is why.
Coal particles have enormous surface area. Bridging — where long polymer chains physically connect multiple particles — is far more effective than charge neutralization at this scale. APAM chains (12-25M MW) are long enough to bridge 5-10 particles simultaneously. CPAM chains are shorter and stiffer.
Our NPAM designed for mining is engineered for exactly this use case, with batch-level quality control from our Zhengzhou facility.
For projects like this, our our APAM for mineral processing delivers consistent results with factory-direct pricing.
APAM also produces larger, more open flocs that settle faster and drain better on the sludge pond floor. And it costs 30-40% less than CPAM. For coal washing, APAM is the right choice every time.
What You Are Actually Treating
Coal washing wastewater is not just dirty water. It contains coal fines (50-500 µm), kaolinite and illite clay minerals, silica, and organic matter from coal decomposition. All of these carry negative surface charge and repel each other. Without PAM, they stay suspended for 7-14 days.
Typical incoming wastewater: 500-2,000 mg/L TSS, 200-1,000 NTU turbidity, pH 6.5-8.0. Target for recycling: <100 NTU (thermal coal) or <50 NTU (coking coal). Target for discharge: <50 NTU in most jurisdictions.
The clay content is the variable that matters most. High-clay coal (kaolinite >15%) needs higher MW and higher dosage. We ask every new client to send us a water sample before recommending a grade — clay content varies by mine and by seam within the same mine.
Dosage Optimization
Do not guess dosage. Run a jar test first. Here is the protocol we send to every new client:
- Prepare 0.1% PAM solution (1g PAM in 1L water, stir 60 min until fully dissolved)
- Fill 6 × 1L cylinders with your coal washing water
- Add PAM at 2, 4, 6, 8, 10, 15 ppm to each cylinder
- Invert each cylinder 3 times gently — do not shake
- Measure turbidity at 30 min and 60 min
- The lowest dosage that hits your target turbidity is your starting point
Field dosage is typically 20-30% higher than jar test dosage because real systems have more turbulence. Start at jar test result + 25%, then fine-tune.
Water Recycling System Design
A basic PAM recycling system for a 1,000 ton/day plant:
- Collection sump — 500-1,000 m³ capacity, collects all wash water
- PAM dosing — 0.1% solution dosed at sump outlet, 3-15 ppm depending on coal type
- Gentle mixing — 2-5 minutes, low shear (high shear breaks flocs)
- Settling pond or thickener — 1-3 hours residence time
- Overflow pump — clarified water back to washing plant
- Sludge removal — settled coal fines removed weekly or monthly
For plants with limited land, a high-rate thickener replaces the settling pond. Same clarification in 20% of the footprint. We can help size the thickener based on your throughput and target turbidity.
Case Study: Queensland Thermal Coal Plant
2,000 ton/day plant — was discharging 2,500 m³/day illegally
Situation
Plant was discharging turbid wastewater into a nearby river — 600 NTU, well above the 50 NTU discharge limit. Facing regulatory action. Fresh water cost: $3,000/day. They needed a solution in 3 weeks.
What We Did
Analyzed their water sample. Bituminous coal, moderate clay content, pH 7.2. Recommended APAM 15M MW at 6 ppm. Shipped 2 tons within 5 days (urgent stock). Supported their system setup via video call.
Results (2 weeks after startup)
Case Study: Kalimantan Coking Coal Plant
1,500 ton/day plant — fine particles, high clay
Note: The 22M MW grade is not a standard catalog item. We custom-produced it for this client's specific clay content. This is something trading companies cannot do.
The Batch Consistency Problem
The most common complaint we hear from coal plants: "First batch worked great, second batch was useless." This happens when you buy from trading companies who source from whoever is cheapest that month.
We are the factory. Every batch is produced on our own lines in Zhengzhou. Every batch is tested for MW (±0.5M tolerance), solid content (≥92%), dissolution time (≤90 min), and residual monomer (≤0.05%). We retain 200-500g samples from every batch for 24 months. If you have a performance issue, we can pull the retained sample and compare.
We supply 30,000+ tons/year to 45+ countries. Coal washing is one of our core markets — we have dedicated APAM grades for it, not repurposed general-purpose grades.
Pricing (2026, FOB China)
- APAM 10-15M MW (lignite): $1,200-1,500/MT
- APAM 15-20M MW (thermal coal): $1,400-1,700/MT
- APAM 20-25M MW (coking coal): $1,600-1,900/MT
- Custom grades (22M+, high clay): Quote on request
MOQ: 500kg first order. FCL (20MT+): 10-12% discount. Delivery: 7-10 days standard, 3-5 days urgent.
Send us your coal washing water sample
We analyze it free and recommend the right grade. If you are in a hurry (regulatory deadline), tell us — we have shipped urgent orders in 3 days.
WhatsApp: +86 150-0381-8598 · Email: info@chinapolyacrylamide.com