Investigation on the rheological and stability characteristics of coal–water slurry with long side-chain polycarboxylate dispersant

A novel comblike polymer, long side-chain polycarboxylate (LcPC), was designed as a dispersant for coal–water slurry (CWS) and synthesized in aqueous solution from the copolymerization of macromonomer polyethylene glycol-acrylate monoester(PA), sodium p-styrene sulfonate (SSS) and acrylamide (AM). PA was prepared by esterifying with polyethylene glycol (PEG200, 400, 600, 800, 1000, 2000) and acrylic acid (AA). The structure of LcPC was characterized. The performance of LcPC as dispersant for the low rank China coal–water slurry (i.e. Shenfu coal) was evaluated and the dispersion mechanism was also explored. Results showed that the dispersant was a polymer with long side-chains modified by ArSO3Na and CONH2 groups. The CWS with LcPC displayed the better rheological and stability characteristics than the traditional dispersant in stock for the low rank China coal (i.e. the apparent viscosity and penetration ratio of CWS with 65 wt.% coal and 0.4 wt.% dispersant were 389 mPa·s and 82.0%, respectively). The properties of the CWS can be further improved in the presence of LcPC because of not only the better electrostatic force with the coal but also the stable steric hindrance of long side-chain.