Understanding mineral behaviors during anthracite fluidized-bed gasification based on slag characteristics

Mineral behaviors were investigated on the basis of the characteristics of three slag samples derived from pressurized ash agglomerate fluidized-bed gasification of Jincheng Anthracite (JC). Examination of the ash fusion temperature (AFT) shows that the AFTs of the slag samples in a reducing atmosphere (1:1 CO2/H2, volume ratio) increase in the order slag formed on the inner face (SI)<slag on the distribution plate (SD)<slag on the central tube (SC). Comparison of surface morphologies of slags indicates that a small part of the SI surfaces are molten and smooth. In SD, only particles attached to aggregates composed mostly of low-melting-point eutectics are molten, whereas SC contains few molten particles. Anorthite is present in SI and SD, and hercynite is present in all three slag samples. In the reducing atmosphere at 1100°C, hercynite and anorthite form in JC ash, and most of the calcium and iron form amorphous matter at 1200°C. Formation mechanisms of the three kinds of slag are discussed.