Transformation Behaviors of Mineral Matter in Lignite Ashes under Reducing Atmosphere

Abstract

To optimize operational parameters of fluidized-bed lignite gasification technology. Experiments have been conducted with Huolinhe (HLH) and Xiaolongtan (XLT) lignite ashes to investigate the mineral transformation behaviors under reducing atmosphere by X-ray diffraction (XRD). The results show that the initial melted parts are primarily result from wustite interacted other minerals under reducing atmosphere. Wustite can react with aluminosilicate minerals to form some low-melting eutectic compounds, and lead to its initial melting temperature 200 °C below the deformation temperature. Mullite is formed at 1000 °C or so, and its content increases and then decreases with the temperature increase, and reaches maximum at 1200 °C. Gehlenite and anorthite come from the reaction between calcium oxide and mullite. Owing to the generation of some gases during mineral transformation under weak reducing atmosphere, many holes are formed on the surface of molten ash.