Nonionic PAM may be tested for fine-coal or mineral-solids clarification in a coal-washing water circuit. Its injection point matters: a product that improves thickener overflow may interfere with flotation if it contacts coal surfaces upstream.
Map water and solids movement
Document screens, cyclones, flotation, thickener, sludge handling and recycle-water return. Record coal source, ash-forming minerals, particle distribution, solids, pH, conductivity and flotation reagents.
Identify where polymer-treated water can return. Sampling only the clarifier can miss a downstream recovery effect.
Separate clarification from recovery
Run settling tests for interface, supernatant, sediment and shear response. Independently verify flotation recovery, concentrate quality and tailings when treated water or polymer can enter the flotation circuit.
Historical research has reported depression of coal flotation by nonionic polyacrylamide under specific conditions, so direct transfer of a clarifier result is not justified.
Control the plant trial
Change one variable at a time, allow circuit residence and record overflow, underflow, polymer consumption, recovered water and flotation indicators. Approve only a dose and injection point supported by the full circuit.