Four humic coal samples are extracted to obtain humic substances (HS), and then subdivided(or purified) to obtain sixteen grades of HS, four from each coal. The effectiveness of these sixteen HS samples as additives for producing coal water mixture (CWM) is tested (w (additive) = 1 % and the the coal used is from the Baiyi coal preparation plant). A linear regression analysis of viscosity versus the additive’s components shows: (1)humic acids(HA) and humin (HM) are much better than fulvic acids (HF) with HA being tbe best, and (2) tke effects of grades of HS on coal dispersion as measured by viscosity are quite different. CWM additive effectiveness correlates positively with the increase of E4/E6,ash content, acid groups, and carboxyl groups, and negatively with the increase of molecular weight, HS content and phenolic alcohol content.
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