Reduction of perovskite-geikielite by methane-hydrogen gas mixture: Thermodynamic analysis and experimental results

Run Zhang; Jie Dang; Dong Liu; Zepeng Lv; Gangqiang Fan; Liwen Hu

doi:10.1016/j.scitotenv.2019.134355

Reduction of perovskite-geikielite by methane-hydrogen gas mixture: Thermodynamic analysis and experimental results

Sci Total Environ. 2020 Jan 10:699:134355. doi: 10.1016/j.scitotenv.2019.134355. Epub 2019 Sep 7.

Authors

Run Zhang¹, Jie Dang², Dong Liu¹, Zepeng Lv¹, Gangqiang Fan¹, Liwen Hu³

Affiliations

¹ College of Materials Science and Engineering, Chongqing University, Chongqing 400044, PR China; Chongqing Key Laboratory of Vanadium-Titanium Metallurgy and New Materials, Chongqing University, Chongqing 400044, PR China.
² College of Materials Science and Engineering, Chongqing University, Chongqing 400044, PR China; Chongqing Key Laboratory of Vanadium-Titanium Metallurgy and New Materials, Chongqing University, Chongqing 400044, PR China. Electronic address: jiedang@cqu.edu.cn.
³ College of Materials Science and Engineering, Chongqing University, Chongqing 400044, PR China; Chongqing Key Laboratory of Vanadium-Titanium Metallurgy and New Materials, Chongqing University, Chongqing 400044, PR China. Electronic address: lwh0423@cqu.edu.cn.

PMID: 31520943
DOI: 10.1016/j.scitotenv.2019.134355

Abstract

The present study investigated the reduction and carbonization behavior of perovskite-geikielite by using CH₄-H₂ gas mixture, which aimed to recycle the titanium resource in titanium-bearing blast furnace slag. Thermodynamic phase equilibrium analysis in the CaTiO₃-CH₄-H₂, MgTiO₃-CH₄-H₂ and CaTiO₃-MgTiO₃-CH₄-H₂ systems was performed by FactSage. The analysis indicated that CaTiO₃ could be ultimately reduced and carbonized to TiC_xO_y by CH₄-H₂ gas mixture at temperature above 1300 °C, while the temperature for reduction of MgTiO₃ was above 1200 °C. MgTiO₃ is found to be reduced prior to CaTiO₃ in the CaTiO₃-MgTiO₃-CH₄-H₂ systems. The reduction experiments of perovskite-geikielite were carried out in a temperature range of 1300 °C to 1450 °C in a flowing CH₄-H₂ atmosphere. Experimental results showed that perovskite-geikielite could be reduced completely to TiC_xO_y at 1400 °C and above after 8 h reduction, while geikielite was reduced prior to perovskite. The reduction and carbonization extent of samples increased with increasing time and temperature when in a low temperature range (below 1400 °C). However, a much higher temperature (above 1400 °C) would hinder further carbonization of TiC_xO_y for the production of deposited carbon. Addition of iron oxides to sample strongly facilitated the reduction reaction, and even promoted the reduction of titanium to be completed at only 1300 °C after 8 h reduction. The gas-solid reaction provided a low temperature method to reduce and carbonize perovskite and geikielite, and thus it provided a possible way to use titanium-bearing blast furnace slag.

Keywords: Methane; Perovskite-geikielite; Titanium-bearing blast furnace slag.