Synthesis And Characterization Of Dispersant For Shenfu Non-caking Coal CWS

Shenfu non-caking coal is a kind of low rank coal, it contains many oxygen functional groups and its inherent moisture content is high, so it’s hard to work out high-concentration CWS with general slurry dispersant. To solve this problem, a kind of dispersant with good matching ability was synthesized and characterized. And the best synthesis process was found out through orthogonal experiment. Properties of CWS prepared with self-made dispersant were tested to analyze the effect of dispersant on preparing Shenfu non-caking coal CWS.Coal quality characteristics were analyzed at the beginning of experiment. Putting both the characteristic and the mechanism of CWS dispersant into consideration, the structure of the dispersant was designed. Taking carboxylic groups and phenyl groups into molecular structure of sulfonated acetone formaldehyde polycondensate(SAF). The aliphatic long-chain structure in SAF molecular could improve the steric hindrance effect. And carboxylic groups could improve stability and mobility of CWS, while phenyl groups were good for matching relationship between dispersant and condensed aromatic rings in non-caking coal.Before the study on the best preparation process condition of dispersant, slurry preparation experiments were carried out. The result showed that when the molecular weight of dispersant was located in the range of 18×104~25×104, the fixed-viscosity concentration of CWS was at a high level, so the molecular weight should be taken as standard for performance of dispersant.Single-factor and orthogonal experiment was carried out to analyze the best preparation process condition for dispersant. Through the analysis of infrared spectrum and the measurement of molecular weight, the best condition was worked out. The best reaction temperature was 90℃, reaction time was 4h, addition ratio of monomer was 0.8:1, and initiator addition was 4%. Under this best condition, the molecular weight was 21.283×104.The properties of CWS prepared under different conditions were compared with each other. The conditions were type of dispersant, addition of dispersant and molecular weight of dispersant. The results showed that when dispersant addition was 0.6%, the fixed-viscosity concentration of CWS prepared from dispersant B-SAF increased by 0.2% compared with dispersant NSF, and increased by 0.8% compared with dispersant LS. Besides the stability and mobility of CWS improved significantly.The results of adsorption properties of dispersant on non-caking coal surface showed that adsorption model of three kinds of dispersants was Langmuir model. The relationship among adsorption constant KL was B-SAF>NSF>LS, and the adsorption amount was B-SAF>NSF>LS. And the adsorption process of three kinds of dispersants accord with the second-order kinetic adsorption model.