Carbothermal reduction and chlorination of Murray Basin Ilmenite

by Yan Li

Institution: University of New South Wales
Department: Materials Science & Engineering
Year: 2012
Keywords: Murray Basin Ilmenite; Carbothermal reduction; Chlorination; Behavior of impurities; Acid leaching
Record ID: 1064897
Full text PDF: http://handle.unsw.edu.au/1959.4/52320


The Murray Basin ilmenite concentrate contains high content of impurities, which make the ore unsuitable for conventional processing. The project studied an alternative approach to processing of Murray Basin ilmenite which includes carbothermal reduction/nitridation and low-temperature chlorination. The aim of the project was to establish behavior of impurities in reduction and chlorination processes. Carbothermal reduction of Murray Basin ilmenite was studied in nitrogen at 1200 – 1400 °C and in the N2-H2 gas mixture at 1150 – 1250 °C; low-temperature chlorination of reduced ilmenite was examined at 200 – 400 °C. The major findings of this project are as follows: • Murray Basin ilmenite concentrate studied in the project contained 58.7 wt% TiO2 and 26.2 wt% Fe2O3. Ti-containing phases included pseudorutile, ilmenite, and rutile; major impurities phases were spinel (Fe, Mg)(Cr,Al)2O4, zircon ZrSiO4 and alumino-silicate Al2SiO5; • Titanium oxides in carbothermal reduction/nitridation were reduced into Ti(O, C, N) and suboxides at 1200 °C in nitrogen and at 1150 °C in N2-H2 gas mixture; no suboxides were observed in reduction at 1400 °C in nitrogen and at 1250 °C in the N2-H2 gas mixture. Iron oxide in ilmenite was reduced into metallic Fe; iron and chromium oxides in the Cr-rich spinel were reduced into Fe-Cr-C alloy; zircon, alumino-silicate, spinels MgAl2O4 and MgCr2O4 were partially reduced at 1250 °C in N2-H2 gas mixture and at 1400 °C in nitrogen; • Chlorination of samples with different extent of reduction was studied: 86% (RS-1), 97% (RS-2) and 62% (RS-3). The extent of chlorination increased with the increased extent of reduction of the sample. Titanium oxycarbonitride, iron and chromium in reduced samples exhibited a high degree of chlorination, while chlorination of Mg, Al and Zr was significant only in RS-2. • Acid leaching effectively removed Fe and Cr from reduced samples. • Chlorination of iron and chromium in samples after leaching was close to completion. The extent of chlorination of Ti in samples RS-1 and RS-2 after leaching was also high but lower, than in samples without leaching. The extent of chlorination of Ti in RS-3, which contained titanium suboxides was relatively low. Carbothermal reduction/nitridation, leaching and chlorination can be a viable technology for processing of Murray Basin ilmenites.