Ability of surfactants to form highly loaded coal-water mixtures

Abstract

Coal tends to aggregate in water. In a coal-water mixture (CWM), the higher the coal content is, the more thickened the mixture is. To highly load a CWM with coal, therefore, it is necessary to use a dispersant. The authors synthesized new types of multibranched high molecular nonionic surfactants that did not contain any alkali metal which would be harmfuls in combustion. Those surfactants were added to CWM samples containing Tatung coal pulverized by a ball mill. As a result, it was found that they contributed greatly to improving the fluidity of CWM, as briefly described below.

(i) Alkylene-oxide-added multi-branched high molecular nonionic surfactants improve their ability to highly load a CWM with an increase in the molecular weight per active hydrogen atom. When the molecular weight is 3,000 to 6,000 or more, they can make a CWM containing 69% coal. (ii) Sodium salt of formalin naphthalenesulfonate condensate, a type of anionic surfactant, can increase the coal content only to a maximum of 65%. (iii) Multi-branched high molecular nonionic surfactants can make a stable CWM.