The Study On Filter Aids Of Fine Coals Synthesized Using Microemulsion Polymerization

An inverse microemulsion system of polyacrylamide was prepared and investigated using surfactants SLL or complexes SLL and Span85 as emulsifiers, butyl alcohol as a cosurfactant, kerosene as a dispersive medium and potassium persulfate as initiator. Threetypes of microemulsion filter aids (1#, 3#, 4# )have been synthesized by microemulsion polymerization. Other two emulsion filter aids,named 2 and 5 , were obtained from microemulsion filter aids 1 and 4# after diluted fourfold with pure water respectively.Vacuum filtration tests were carried out on six rank coals employing these five compounds as filter aids. The filtration effects were characterized by cake moisture and filtration rate. Zeta potential of coal particles were measured as a function of these five reagents as well in electrophoresis apparatus trophoresis. Change regularity of zeta potential were analysed as dosage increases. Besides, the filtration-aid mechanics of different reagents wereanalysed.The results of filtration tests show that the five filter aids havegood filtration effects on the six coals. Reagent 1 has the best filtration effect on anthracite coal with a cake moisture reduction from 31.76% to 12.80%, i.e. 18.96% at dosage 16.8Kg/t. Filtrationrate was improved significantly from 0.21 L/m2 s to 2.55 L/m ç±¹ at the same time. Reagent 2* helps producing the lowest cake moisture with coke coal. The lowest cake moisture is 12.60% at dosage 10.5Kg/t. Compared with the blank test, the cake moisture reduced 11.70%. Reagent 5# has the fastest filtration rate with anthracite coal as the filtration rate increases to 4.08 L/m2 s at dosage 31.5 Kg/t, and the filtration rate increase is 3.87 L/m2 s when compared with the blank test.Both reagents of 1# and 3# have good filtration effects on thesix coals. 2 reagent is suitable to low and medium rank coals. It is a disadvantage for reagent 3# to containing Span85 since Span85 shows powerful frothing capacity which is not desirable in dewatering operations.In addition, the results of flotation test showed that these reagents can improve the collecttability and selectivity of flotation. So these reagents are favorable for flotation, too.