Study On Corrosion Mechanism Of COREX Refractory Lining

COREX is an emerging and environmental melting-reduction process. It is of great significance for longer lining life and more stability of manufacture to study the corrosion mechanism of refractory lining. Firstly, macroscopic erosion of each part in the melting gasifier was studied. Then, refractory erosion process and mechanism of each part were studied by means of chemical analysis, XRD, SEM and determination of physical characteristics. From this study, the conclusions can be summarized as follows:(1) There is almost no obvious change about refractory brick size of vault zone and clearance zone with a small erosion. However, refractory brick in drip zone is eroded seriously.(2) In the upper vault zone, it firstly forms a layer of low melting point compounds on the refractory brick surface because of the reaction among K vapor, furnace burden particles and refractory material components. Then some of K vapor enters the inside of refractory brick and participates in the chemical reaction between refractory components, which makes refractory brick volume expansion and strength reduction. With the position down, the temperature of refractory brick work layer increases further. Molten slag whose soakage to refractory brick enhances reacts with base material inside the refractory brick and forms low melting point compounds. The low melting point compounds which form in high temperature zone can seal the opening stomatals on the surface of refractory brick better, which stop K vapor from entering the inside of brick and further eroding at this moment.(3) In the clearance zone, it forms the low melting point compounds on the refractory brick work layer because of the reaction among K vapor, furnace burden particles and refractory material components, which makes refractory brick inside volume expansion and strength reduction.(4) In the drip zone, the damage of refractory bricks is mainly due to the flow of molten slag erosion process on the surface of refractory brick, which results from the combined interaction of molten slag erosion and molten slag mechanical erosion. A second sintered reaction to refractory brick in this zone has further improved the density and high temperature strength, which is advantageous to improve slag invasion resistance and mechanical erosion resistance of refractory brick. There is negative pressure condition near the tuyere, which makes K vapor easily assembled and stay in the refractory brick near there. The selection of refractory brick in the drip zone should both consider its performance of resistance to molten slag penetration and molten slag washing.