Most coal washing plants use anionic polyacrylamide with a molecular weight between 6 and 18 million. Of course, there are special circumstances, and non-ionic polyacrylamide and cationic polyacrylamide can also be used according to water quality needs. When washing coal in a coal washing plant, first add the dissolved polyaluminum chloride solution to the raw coal washing water, start stirring, about 10 seconds, then add the dissolved anionic polyacrylamide solution, and then start stirring, about half a minute, so that the polyacrylamide solution is fully mixed The wastewater is mixed, and the flocculation reaction formed in the slime water, as well as the formed flocs and the precipitation effect can be clearly seen after mixing.

Cationic polyacrylamide is required in the process of coal slurry cake pressing in coal washing plants, and cationic polyacrylamide with low ionicity (10-20 ionicity) is generally used. When in use, add an appropriate amount of dissolved cationic polyacrylamide solution to the wastewater, and use the positive charge attached to the molecular chain to neutralize the negative charge on the surface of the colloidal particles in the slime water, accelerate the coagulation of the sludge, and use it at the same time. The molecular weight entangles the sludge particles together, squeezes out the water in it, and achieves the purpose of sludge dewatering. Of course, in addition to the use of anionic polyacrylamide and cationic polyacrylamide, there are special cases of non-ionic polyacrylamide, mainly based on water quality to determine the situation.