Abstract
Using an upgraded low rank coal would be effective to decrease the preparation cost of a coal water mixture (CWM). Some upgrading processes for low rank coals have been developed in recent years. On the other hand, the surface characteristics of an upgraded coal would be more hydrohobic rather than a normal bituminous coal. Therefore, the selection of suitable additives for both fluidity and stability of CWMs with upgraded coals is important. In this study, Indonesian coal (Banjarsari -Tanjung Enim) was used to prepare a CWM and twelve surfactants and four stabilizers were examined. From the experimental results, a CWM with the addition of both condensation product of formalin and naphthalen sulfonic acid (NSF-Na+) and bio-polysaccharide (S-194) showed good fluidity and stability. The coal concentration of the CWM was 60.5 % at the apparenet viscoity of 1 Pa · s. The information obtained in this study for various kinds of additives should be valuable for the preparation of CWMs.
