Precautions for polyacrylamide in coal washing:

1. For the treatment of coal slime wastewater, polyacrylamide PAM for coal washing must be added in an appropriate amount to effectively exert its flocculation effect. It can be determined by experiments based on the selected coal slime water treatment process and coal slime water properties. Small dosage will lead to slower coal slime sedimentation, and the concentrated overflow is very likely to exceed the standard, and the required circulating water index cannot be guaranteed.

2. Excessive dosage, although it accelerates the sedimentation rate of coal slime, is easy to cause the concentration of concentrated underflow to be too high. Excessive dosage sometimes makes the concentrated underflow concentration as high as 700g/L or more, and the content of polyacrylamide in the underflow increases, which is unfavorable for underflow transportation and filter pressing. When unloading coal cakes during filter pressing, it is not easy to fall off, which also causes waste of reagents. Generally, the concentration of concentrated underflow is required to be 500g/L, which can meet the filter pressing production.

3. Polyacrylamide for coal washing must be effectively dispersed and carefully dissolved to avoid the adhesion between particles due to the rapid dissolution of the powder surface, resulting in "fish eyes" that cannot be dissolved inside the particles.

4. The storage stability of dissolved flocculants is poor and they should be used within 24 hours after dissolution. If the viscosity decreases after 2-3 days, the function will be reduced.