Reduction and subsequent carburization of pre-oxidation magnetite pellets

Hydrogen-Based Direct Reduction of Combusted Iron Powder: Deep Pre-Oxidation, Reduction Kinetics and Microstructural Analysis

“…However, the former shows systematically faster reduction kinetics, up to five times faster [7], compared with the use of CO. Direct reduction has been mostly studied on iron ores in the form of pellets (>1 mm) [8][9][10][11][12][13][14][15][16][17] and fines (<1 mm) [14,16,[18][19][20][21][22], and more rarely on pure iron oxide fines [23][24][25][26] and single crystals [27][28][29]. Due to the different experimental set-ups and features of iron ores (in terms of ore type, shape, size, microstructure, chemical composition, porosity, etc.…”

“…Completely oxidizing the combusted products to 100 % hematite could increase the overall energy efficiency by recovering the last 5 % of stored energy and by accelerating the HyDR kinetics. Deep pre-oxidation of magnetite ores has been observed to strongly increase their subsequent HyDR kinetics, due to the formation of micro-cracks [38], an increase in open porosity [15], and phase-transformation-induced microstructure refinement [37]. Enhanced reducibility of magnetite ores was found for a pre-oxidation step conducted in a temperature range of 700-900 • C by Chen et al [15] and of 800-1000 • C by Monsen [37].…”

“…Deep pre-oxidation of magnetite ores has been observed to strongly increase their subsequent HyDR kinetics, due to the formation of micro-cracks [38], an increase in open porosity [15], and phase-transformation-induced microstructure refinement [37]. Enhanced reducibility of magnetite ores was found for a pre-oxidation step conducted in a temperature range of 700-900 • C by Chen et al [15] and of 800-1000 • C by Monsen [37]. Zheng et al [22] also investigated the influence of the pre-oxidation temperature and oxidation level of magnetite ores on the ensuing HyDR.…”