Corrosion of MgAl2O4 Spinel with Different Al2O3 Contents in Iron-Containing Gasifier Slag

The MgAl2O4 spinel ceramic specimens with five different alumina contents ( w(Al2O3)=66%,72%,78%,85%,90%) were prepared using alumina micropowder and magnesia micropowder as raw materials, after mixing, shaping, drying, and heating at 1800 °C. The crucible specimens were tested for slag corrosion with commercial gasifier slag at 1500 °C for 2 h under oxidazing and reducing atmosphere. The specimens before and after slag test were studied by analyzing the microstructure and element distributions of corroded specimens with XRD, SEM and EDS. The results show that the slow dissolution of spinel into slag was observed because a low melting point material was formed by spinel reacting with CaO and SiO2 in slag on the surface of the spinel block. Meanwhile, FeOx in the slag was absorbed around the surface of spinel block to form the multiple solid solution, which was composed of MgO-Al2O3-FeOx and had a denser microstructure. The absorption of FeOx in slag had contributed to the resistance to slag penetration for the spinel. The relationship between the absorption capacity of spinel on FeOx and the chemical composition of spinel was discussed.

Effects of Atmospheric Conditions on Slag Corrosion Resistance of Lightweight Al2O3-MgO Castables

By adopting dynamic induction furnace corrosion test, the corrosion mechanism of lightweight Al2O3-MgO castable with different environmental oxygen partial pressure was investigated through macro- and micro-analysis, XRD and thermodynamic simulation. The atmospheric condition was set to P(O2) = 0.21 atm or P(Ar) = 1.0 atm. The attained results showed that a reduced slag corrosion but intensified slag penetration happened at low environmental oxygen partial pressure condition. With P(O2) = 0.21atm, Mn and Fe in slag were present in the form of divalent and/or trivalent cations and were incorporated into spinel to form MnFe2O4 solutions and MgAl2O4 solutions during corrosion process. Since Fe, Mn ions are largely consumed, liquid with high viscosity formed and the continuing infiltration was suppressed. Under P(Ar) =1.0 atm, corrosion on castable aggregates was significantly weakened, and the reaction products under this condition are mainly MgAl2O4 and CA6.

Modeling and experiment of slag corrosion on the lightweight alumina refractory with static magnetic field facing green metallurgy

Electromagnetic field is applied widely in metallurgy and other high temperature processes, and affects the behavior of melts. The lightweight alumina based carbon free refractory is of importance for energy-saving, consumption reduction and high quality steel production, and the slag corrosion resistance is significant concerning its service life. Does electromagnetic field control the slag corrosion behavior on the lightweight alumina refractory? In this paper, a multi-field coupled model was established to describe the slag corrosion process in an electromagnetic field. The mathematical modeling in combination of experiments was applied to clarify slag corrosion behavior of lightweight alumina refractory in static magnetic field. The simulation results agree with that of the experiments, which means the proposed model is promising for slag corrosion modeling. The results show that the combination of the slag properties change, and electromagnetic damping caused by MHD (magnetohydrodynamics) effect can enhance the slag corrosion resistance by inhibiting slag penetration and promoting formation of a directional isolation layer, and be beneficial to high-quality clean steel production.