INFLUENCE OF SURFACTANTS ON FILTER CAKE PARAMETERS DURING VACUUM FILTRATION OF FLOCCULATED IRON-ORE SLUDGE

The influence of certain surfactants on the dewatering of fine iron or e sludge flocculated with anionic flocculants has been investigated in a laboratory-scale vacuum filtration unit. The filtration data have b een used in calculating the cake parameters from an integrated form of Darcy's lau. A narrow concentration range of surfactant enables reduc tion of the specific cake resistance and an enhanced rate of filtratio n. The non-ionic surfactant polyethylene oxide (PEO) was most effectiv e in reducing the moisture content of the cake. Filter cake with 12.6% moisture content has been obtained using this surfactant. The surface tension reduction mechanism is responsible to some extent for the enh anced dewatering, but does not account for all the effects. A complex surfactant adsorption mechanism in the presence of flocculants seems t o play a greater role in enhancing dewatering. (C) 1998 Elsevier Scien ce S.A. All rights reserved.