A study of formation behavior of porous structure induced by selective chlorination of ilmenite

Abstract

Ilmenite, a titanium ore, contains significant iron oxide impurities, and it is essential to selectively remove these impurities during the titanium production process. According to thermodynamic behavior, a space remains empty to form a porous structure after iron oxides are removed. In this study, we selectively chlorinated ilmenite using a fluidized bed reactor to analyze the porous structure formed after processing the ilmenite ore. The removal rate of iron oxides in ilmenite increased with reaction time. When the experiment was performed for 40 min, approximately 96.5% of the iron oxides were removed. We analyzed samples subjected to the 40 min reaction to investigate the pore microstructure formed during chlorination. Surface observations using scanning electron microscopy revealed that the surface of the chlorinated ilmenite ore formed a porous structure, which differed from the dense surface of raw ilmenite. We used the BET method for a detailed analysis of the structural characteristics, specific surface area, and pore size distribution of the ore, and our observations confirmed changes in the pore characteristics inside the ore during the chlorination reaction. The raw ilmenite had a high proportion of micropores smaller than 100 nm, thereby exhibiting a high specific surface area. Most of the pores on the chlorinated ilmenite were between 100 and 200 nm, thereby exhibiting relatively low specific surface area. We compared the BET analysis results with the actual shapes and sizes of the samples by transmission electron microscopy of sample cross sections; these shape and size results had a similar tendency to the pore size distribution analysis results.