Evaluation of Properties of Hyper-coal with Iron Oxide Addition in Thermoplastic Range

Abstract

The effect of iron oxide on coals and Hyper-coal (HPC) during caking temperature was investigated. To reveal the effect of the iron oxide reduction reaction on the thermoplastic properties, iron oxide reduction ratios were calculated from titration and gas analysis, and the thermoplastic properties of coal or HPC with and without iron oxide were estimated using thermogravimetric analysis and the Gieseler test. In addition, to investigate the mechanism of the change in the thermoplastic properties of HPC, the reduction ratios calculated from the titration and gas analysis were compared, and the crystal structure of HPC was analyzed using transmission electron microscopy (TEM). As a result, the iron oxide reduction reaction took place in the thermoplastic range, and the weight loss of samples with iron oxide addition increased while the fluidity decreased. On the basis of gas analysis, it was found that the reduction ratio was mainly composed of oxygen derived from H2O vapor. This result suggested that hydrogen atoms generated from the thermoplastic components of the HPC were involved in the reduction reaction. Thus, the polymerization rate of HPC was promoted near iron particles in the thermoplastic range, and the crystal structure of HPC with iron oxide addition was different between near and far from the iron particles. We, therefore, revealed that the reduction reaction by hydrogen atoms from HPC occurred in the thermoplastic range, and that the polymerization rate of HPC with iron oxide addition was increased due to decomposition of the thermoplastic components of the HPC.

Performance Optimization and Efficient Application of Highly Reactive Iron Coke: Research Progress and Future Trend

“…The above raw materials were pressed and shaped at the temperature and pressure of 60 °C and 29.4kN cm À1 , respectively, and finally carbonized at a constant temperature of 1000 °C for 4 h. Iron coke produced under these conditions had a 3977 N compressive strength with a 69.7% CRI and a 14.1% CSR, as shown in Figure 4. Uchida et al [58,59] utilized hypercoal (HPC) as a binder to improve the strength of iron coke. The results showed that HPC can effectively improve the strength of iron coke by enhancing the bonding of coal particles.…”

“…Moreover, the crushing strength of iron coke was increased from 18.15% to 76.41% when coal tar pitch was added with 10%, as shown in Figure 6a. Uchida et al [58,59,71] used HPC as a binder to prepare iron coke and investigated the relationship between the strength and microstructure of iron coke after the addition of HPC. The results showed that mutual adhesion between coal particles was one of the factors affecting the strength of the iron coke, which could be evaluated by the pores with roundness less than 0.05, as shown in Figure 6b-d.…”

Effect of Iron Ore Reduction on Ferro-coke Strength with Hyper-coal Addition

“…No remarkable differences are observable; however, the existence fraction of the "defect" slightly decreases with increasing HPC addition. Uchida et al 12) reported that iron oxide exists as magnetite (Fe 3 O 4 ) independent of the blending ratio of HPC at 600°C in the carbonization process, and the ratio of the reduction reaction of iron oxide progressing in the high temperature condition is constant. Therefore, magnetite is reduced to metallic iron via wustite (FeO), and the coke matrix is correspondingly diminished.…”

“…Conversely, the reduction reaction of hematite (Fe 2 O 3 ) by hydrogen atoms in coal or HPC is enhanced at the thermoplastic temperature. 12) Moreover, because HPC has a higher fluidity than coal, the probability of HPC contacting iron oxide is high, and HPC enhances the reduction reaction of iron oxide. Consequently, the different blending ratios cause different conversions in the reduction reaction of iron oxide at the resolidification temperature, and the "defect" would be generated by the reduction reaction of hematite, which is not reduced at the thermoplastic temperature.…”