The effect of inorganic salt modification of sludge on the performance of sludge-coal water slurry

Abstract

Coal water slurry (CWS) is a coal-based liquid fuel with the characteristics of high efficiency and low pollution. Municipal sludge, as a substantial solid waste, is of increasing attention due to the severe environmental pollution and difficult disposal. In this study, sludge is modified by inorganic salt solution and then used to prepare salt-modified sludge coal water slurry (SSCWS). The results showed that the sludge modified by KCl and AlCl3 can reduce the viscosity of CWS. While low concentration of CaCl2 tends to slightly increase the viscosity of CWS and higher concentration of CaCl2 can reduce the viscosity. It was found that among the three salts used in the experiment, the higher the cation valence state is, the easier and more the dispersant molecules are adsorbed on the surface of coal or sludge particles to improve the dispersion of coal and sludge particles, which was the main reason for improving the slurryability of SSCWS.