Coal washing wastewater is one of the most challenging types of industrial wastewater. It contains:

• Fine coal powder and clay
• High suspended solids (SS)
• Residual flotation reagents and oil
• High turbidity and dark color

When we first visited our clients’ sites in Vietnam and Indonesia, the water after coal washing was thick, black, and extremely difficult to settle. The key to treatment lies in efficient coagulation, rapid floc formation, and deep sedimentation.

Clients often face:

• Poor sedimentation — fine coal particles remain suspended
• Thick, dark water that is hard to clarify
• High chemical consumption due to fluctuating water quality
• Unstable sludge that is difficult to dewater

We’ve observed that:

• Indonesia, coal washing wastewater contains high iron and fine clay, requiring stronger coagulants like PFS (Polyferric Sulfate).
• Vietnam, the challenge is reagent residuals — we recommend polyaluminium chloride + polyacrylamide to improve sludge compactness.
• Russia, low temperatures slow down reactions; thus, low-temperature polyaluminium chloride performs better.

How to select PAM based on the factory?

Recommended Chemical Combination for Coal Washing

Sand washing wastewater mainly comes from natural sand and stone washing processes.
It typically contains:

• Fine quartz particles
• Clay, silt, and dust
• Small amounts of surfactants or organics

Although this wastewater seems simple, it’s often highly turbid and difficult to settle quickly.

Our clients’ most common challenges include:

• Slow sedimentation and cloudy recycled water
• Frequent equipment clogging due to mud build-up
• Inconsistent water quality from varying sand sources
• High operating costs from excessive chemical dosing

Regional feedback we’ve gathered:

• Indonesia: Clay-heavy sand leads to higher turbidity — we recommend polyaluminium chloride + anionic polyacrylamide.
• Vietnam: Fine silt requires a stronger flocculant and longer settling time.
• Singapore: Compact systems need chemicals with fast reaction rates.
• South Africa: Focus on recycling clarity and reduced maintenance frequency.

Recommended Chemical Combination for Sand Washing