Reduction of FeO in Molten Slag by Solid Carbonaceous Materials for HIsarna Alternative Ironmaking Process

Abstract

To investigate the use of biomass in the novel HIsarna technology, the reduction of FeO in the slag by chars produced from thermal coal (TC), charcoal (CC), and Bana grass char (BGC) was studied. A drop tube furnace coupled with a quadrupole mass spectrometer (DTF-QMS) was employed to study the injection of chars into pre-melted slag in the temperature range between 1450 °C and 1525 °C. The reduction rate was calculated from evolved gases and the extent of FeO reduction was confirmed by wavelength-dispersive X-ray fluorescence (WDXRF). The FeO reduction proceeds through two stages, starting with a rapid reduction, which is dependent on the carbon type, and followed by gradual leveling off. The reduction rate with the charcoal char (CC) was the highest, over 60 pct reduction was achieved in the first 500 seconds at 1500 °C, while ~ 50 and 40 pct achieved with TC and BGC chars, respectively, for the same reaction time. The kinetic analysis suggests that the first and second stages of the reaction can be described by the second-order (F2) and three-dimensional diffusion (D3) models, respectively. The apparent activation energy values for the first stage were 290, 229 and 267 kJ/mol for reactions with TC, CC and BGC chars, while 265, 369, and 282 kJ/mol were obtained for the second stage. Based on the experimental data and kinetic results, it can be concluded that the first stage is controlled by chemical reactions on the carbon surface, and the second stage is influenced by a mixed-controlling mechanism.

Study on the Bath Smelting Reduction Reaction and Mechanism of Iron Ore: A Review

“…For the study of the smelting reduction reaction between liquid iron oxide and molten iron or carbon-containing materials, the experimental methods used by previous authors are shown in Figure 8 [5,[57][58][59][60]. [61,62].…”

“…In addition, the differences in the decomposition behavior of hematite in CO 2 and inert (N 2 ) atmospheres were compared by previous authors [25]. The oxygen loss percentage (R) is the ratio of the weight loss of oxygen of a sample, ∆m oxygen , to the total oxygen mass of the iron oxide in sample, m tot-oxygen , as shown in Equation (5).…”

“…The limiting step of the FeO smelting reduction of slag at different FeO contents is shown in Table 4. (2) Carbonaceous materials Khasraw et al [5] compared the smelting reduction effect of thermal coal (TC) and charcoal (CC) on the slag system of the HIsarna process; the reduction of CC was better for FeO than that of TC. The results of the reduction rates of different carbonaceous materials in FeO-bearing slag showed that the reduction rates of fixed coke rods were slightly worse than those of graphite rods.…”

“…Furthermore, when Khasraw et al [5] used carbonaceous materials to reduce FeO in a CaO-SiO 2 -Al 2 O 3 -MgO-FeO slag system, the temperature had a large effect on the reduction index of FeO in carbon reduction slag, and the reduction index increased with increasing temperature. Temperature had a significant effect on the variation in gaseous products CO and CO 2 .…”

Kinetic Study on Reduction of FeO in a Molten HIsarna Slag by Various Solid Carbon Sources

“…Many researchers studied [11][12][13][14][15][16][17] the reduction of iron oxides in solid or molten slag by different types of carbon, and some of the studies are summarised in Table I. Most authors agree that the mass transfer of FeO in the liquid phase is the rate limiting step during slag and solid carbon reaction.…”