Precipitation kinetics of anosovite in modified high Ti-bearing blast furnace slag

¹ College of Materials Science and Engineering, Chongqing University, Chongqing 400044, P.R. China
e-mail: jeopardize@126.com
² School of Metallurgical and Ecological Engineering, University of Science & Technology Beijing, Beijing 100083, P.R. China
³ School of Chemical Engineering, The University of Queensland, Brisbane, Qld 4072, Australia

Received: 20 October 2014
Accepted: 3 February 2015

Abstract

In the present study, the modified high Ti-bearing blast furnace slag was prepared by adding 2.5% B₂O₃. The precipitation behavior of anosovite was studied by the procedure which was pre-melted at 1360 °C for 20 min, cooled to 1260 °C at the rates of 0.25–4.0 °C/min, and then quenched into the ice water after duration for 60–240 min at 1260 °C. Phase assemblage and composition of the slag quenched from high temperature was determined by the electron probe X-ray microanalysis (EPMA). The micrographs of slags were obtained by optical microscope and the dimension data of anosovite was collected by ImageJ software. The theory of Crystal Size Distribution (CSD) was adopted for data processing and crystallization kinetics study. The results showed that B₂O₃ distributed only in liquid phase of the slag and anosovite was the host mineral precipitated from the current modified high Ti-bearing blast furnace slag. The decrease of cooling temperature and prolonging holding time were both beneficial to grain coarsening of anosovite. The growth rate (G) and nucleation rate (J) of anosovite phase were similar and they both decreased exponentially with holding time.