Investigation on Ash-Fusion Characteristics of Livestock Manure and Low-Rank Coals

Large amounts of livestock manure are produced annually, and cogasification offers a promising method for large-scale and clean use of manure. To investigate the ash-fusion characteristics (AFC) of livestock manure and coal, and their variation mechanisms, the AFCs of two coals (Yima long-flame coal and Husheng lignite), two manures (cattle manure (CM), and swine manure (SM)), and their mixtures were explored. An increase in the ash mass ratio of the CM or SM increased the sintering temperature (Ts) of two mixed coal ashes (the SM enhanced the Ts more than that of the CM); however, their ash-fusion temperature (AFT) decreased first and then increased (the turning points for the Yima long-flame coal ash mixture were CM: ∼60% and SM: ∼40%, and those for the Husheng lignite were SM: ∼70% and SM: ∼50%). The Ts was induced by partial particle surface fusion, and was related to the formation of a low melting eutectic (e.g., binary systems for K2SiO3–Na2Si2O5 and Na2S–FeS) and their contents. The AFT indicated that the bulk melting property was determined mainly by ash composition, especially for a basic/acid ratio. The disappearance of mullite and the formation of high melting-point phosphates (e.g., KCaPO4, K2CaP2O7, and Ca2.71Mg0.27(PO4)2) resulted in AFT fluctuations of the mixtures.