Enhancement of Rutile Formation by ZrO₂ Addition in Ti-bearing Blast Furnace Slags

Abstract

Enhancement of rutile crystallization in Ti-bearing Blast Furnace (Ti-BF) Slag caused by various ZrO₂ additions was clarified by Single Hot Thermocouple Technique (SHTT). Time-temperature-transformation (TTT) curves were obtained to analyze the variation trend of crystallization behavior. The results showed that the incubation time of primary crystal, i.e., rutile, at high temperature was first prolonged with increasing ZrO₂ addition from 0 to 3 wt.%, and then visibly shortened with further addition of ZrO₂ up to 5 wt.%. However, final amount of crystal precipitated was monotonously enhanced by the increasing ZrO₂ addition. Meanwhile, Fourier Transform Infrared spectroscopy (FTIR) test was applied to investigate structure of the slag and it was found that degree of polymerization (DOP) for the slag was enhanced and the structural group related to Zr–O–Zr group became more pronounced with increasing ZrO₂ concentration, which agreed well with the variation trend of the crystallization behaviors of slags. These results have highlighted that addition of ZrO₂ could enhance rutile crystallization, which is of great importance for potentially extracting Ti element from the slag.