Effect of slag composition on corrosion resistance of high chromia refractory bricks for industrial entrained-flow gasifier

The slag composition corresponding to different coals varies significantly, which directly affects the operation of industrial entrained-flow gasifier and the service life of refractory bricks. In this study, the corrosion resistance of several typical coal slags for gasification on high chromia refractory bricks was comparatively investigated by static laboratory crucible tests and thermodynamic simulations. The results demonstrated that the corrosion degree of high chromia refractory bricks by different coal slags was high-Ca/Na slag > high-Fe slag > high-Si/Al slag. The surface structure of the refractory was relatively flat after corrosion by high-Si/Al slag, and the primary corrosion reaction was the partial dissolution of the matrix by the slag. High-Fe slag was prone to the precipitation of iron phases as well as the formation of (Mg, Fe) (Al, Cr)2O4 composite spinel layer at the slag/refractory interface. The high-Ca/Na slag was susceptible to react with the refractory to yield a low melting point phase, which led to the destruction of the matrix structure of the refractory and an isolated distribution of particles. In addition, the monoclinic ZrO2 in the refractory reacted with CaO in the slag to formed calcium zirconate, which loosened its phase toughening effect, was the primary factor that aggravated the refractory corrosion.