PURPOSE: The titled viscosity depressant that is obtained by condensation reaction between an aromatic sulfone bearing a phenolic hydroxyl and an aliphatic aldehyde, thus enabling an aqueous slurry of finely powdered coal to be pumped by addition thereof in a small amount.
CONSTITUTION: The condensation reaction of (A) an aromatic sulfone bearing phenolic hydroxyls such as sulfone of phenol or cresol with (B) an aliphatic aldehyde such as formaldehyde is conducted so that the condensation degree becomes 2.0W10, or the condensation reaction between compounds A, B and a compound bearing imino groups such as guanidine and/or a compound bearing carbamoyl or thiocarbamoyl groups such as urea is conducted to give the objective viscosity depressant. The salt also may be used as a viscosity depressant. Cleaned coal is preferably used, usually 0.03W2.0wt% of the depressant is added to a coal-water slurry of higher than 70% concentration.
EFFECT: The dehydration process may be eliminated.
HONJIYOU SHIYUUICHI
MAYUZUMI FUKUNOBU
