Study on effect of Shanxi high ash content and ash fusion temperature coals on fluxing mechanism of limestone

The floated coal samples with different ash contents were obtained by coal washing, and the effect of ash content on addition of fluxing CaCO₃ was investigated. The results show that silica content and silicon to aluminum ratio (Si/Al) of ash decrease with decreasing ash content. The AFTs of coal ashes change with increasing CaCO₃ addition. The additive CaCO₃ content is closely related to the mineral formed at high temperatures and their contents. Furthermore, for the FH and SH coals after floatation, the viscosity of slag with CaCO₃ addition exhibits a behavior of glass slag, and also has a large slagging temperature range. The properties of the floated coal ash slags with CaCO₃ addition well meet the requirement of slag tapping in entrained flow gasifier. It is an effective way for Shanxi high ash content and ash fusion temperature coals to combine coal washing and CaCO₃ adding to adjust the ash flow properties in entrained flow gasification.