Effect of Co2O3 on Oxidation Induration and Reduction Swelling of Chromium-Bearing Vanadium Titanomagnetite Pellets with Simulated Coke Oven Gas

This study discusses the oxidation induration and swelling behavior of chromium-bearing vanadium titanomagnetite pellets (CVTP) with Co2O3 additions. The reduction swelling index (RSI) and compressive strength of reduced CVTP (CSRC) were investigated with simulated coke oven gas (COG). The results show that the compressive strength (CS) of CVTP decreases from 2448 to 1983 N and the porosity of CVTP increases from 14.86 to 22.49% with increasing Co2O3 additions. The Co2O3 mainly exists in the form of CoFe2O4 in both of CVTP and reduced CVTP, and the CoFe2O4 is hard to be reduced by thermodynamic calculation. The Co-bearing phase mainly distributes on gap edges and among adjacent hematite grains. Many cracks and pores distribute along the grain boundaries and damage the connection of hematite grains. The CSRC decreases from 901 to 376 N, and RSI of reduced CVTP increases from 5.87 to 9.05% with increasing Co2O3 additions. The Co2O3 addition facilitates the aggregation and diffusion of metallic iron particles, and the aggregations of metallic iron thicken the lamellar crystals. The pores and interval of grains enlarge with increasing Co2O3 additions. This study can supply the theoretical and technical basis for the utilization of CVTP and waste residue-bearing cobalt with COG recyclable technology.