Melting and Flow Behavior of Coal Ash at High Temperatures Based on SiO₂–Al₂O₃–CaO/Na₂O Pseudoternary Phase Diagram

Abstract

The entrained-flow gasifier has a better adaptability to various coals. The composition of coal ash is an important factor affecting the high-temperature flow characteristics of molten slag. Based on the SiO 2 −Al 2 O 3 −CaO/Na 2 O ternary phase diagram, the high-temperature molten flow characteristics of slag located in the main phase regions of feldspar, melilite, diopside, and mullite were investigated by experiments and thermodynamic software calculations. The results indicate that the melting process of ash in the three phase zones is influenced by different factors. It was discovered by infrared spectroscopy analysis that the slag was dominated by Si 2 O 5 2− ion clusters in the feldspar region. The slag in the diopside region had a slightly higher proportion of simple silicate ion clusters than the slag in the feldspar region, resulting in better fluidity. This is significant for revealing the mechanism of coal ash melting and flowing and guiding industrial coal blending.