Binder Effect on Corrosion Mechanism of Al ₂ O ₃ ‒Cr ₂ O ₃ Castables for Copper Anode Fire Refining

ABSTRACT To improve the performance and lifetime of refractories used at the tuyere zone in copper anode fire refining (CAFR) furnace, Al 2 O 3 ‒Cr 2 O 3 castables bonded with reactive magnesia (R‒C), hydratable alumina (H‒C), and calcium aluminate cement (C‒C) were comparatively investigated in terms of resistance to corrosion and infiltration by CAFR slag. The thermal shock resistance of the prepared castables was also studied. Results indicate that the R‒C castable formed Mg(Al,Cr) 2 O 4 spinel in situ at elevated temperatures. The Mg(Al,Cr) 2 O 4 spinel could incorporate Cu 2+ and Fe 2+ /Fe 3+ from the CAFR slag to form (Mg,Cu,Fe)(Al,Cr,Fe) 2 O 4 spinel, which blocked pores in the castable matrix and thus hindered further slag infiltration. Consequently, R‒C castables exhibited superior resistance to slag corrosion and infiltration compared with H‒C and C‒C castables. In addition, R‒C castables showed the highest residual strength ratio after thermal shock testing.