Effect of Oxygen Enrichment on Sintering with Combined Usage of Coke Breeze and Gaseous Fuel

Abstract

The temperature in the sintering bed is preferably maintained between 1 200°C and 1 400°C during sintering to produce high strength and reducibility sintered ore. To achieve this condition, the technology of combined usage of coke breeze and gaseous fuel, which is fed properly from the top surface of the sintering bed, was developed. In this paper, the effect of oxygen enrichment with combined usage of coke breeze and gaseous fuel on the heat pattern in sintering bed and cold strength of sintered ore was investigated. The cold strength of sintered ore was improved by the oxygen enrichment in the pot test. Then, the holding time over 1 200°C during sintering was extended and improvement of strength would be attributed to promotion of the sintering reaction. By the simulation model calculations based on chemical kinetics, it is considered that the further extension of the holding time over 1 200°C due to oxygen enrichment is caused of an increase in the distance between the combustion points of the coke breeze and gaseous fuel. However, improvement of the cold strength reached saturation over 32 vol.% of the oxygen concentration in suction air. It is also considered that the excessive increase of the distance between the combustion points of coke breeze and gaseous fuel decreases overlap of respective heat transfer and doesn't contribute to the expansion of holding time over 1 200°C.

Effect of Oxygen Enrichment on Mineral Texture in Sintered Ore with Gaseous Fuel Injection

“…The LNG and oxygen concentrations were controlled to the specified values by adjusting the injection gas flow rate. First, in order to confirm the effect of combined gaseous fuel and oxygen injection on the temperature distribution in the sintering bed, which was reported in a previous report, 8) a thermocouple was inserted to a distance of 500 mm through a hole provided in the side wall at a position 130 mm below the sintering bed surface. The thermocouple used here was one R sheath type.…”

“…7) Moreover, in a previous report, 8) a further extension of this holding time was also possible by simultaneously injecting the gaseous fuel and oxygen. The mechanism of this phenomenon can be explained as follows: Figure 10 shows a schematic diagram of the heat patterns and the positions of solid fuel (coke) and gaseous fuel (LNG) combustion points with the conventional method, the gaseous fuel injection method, and the combined gaseous fuel and oxygen injection method.…”

“…In a previous report, we also described a technique for extending the holding time at the proper sintering temperature by applying oxygen enrichment to this technology. 8) To date, many studies have investigated the effect of the sintering bed atmosphere composition on the mineral texture of sintered ore. Matsuno et al clarified the mineral formation process of sintered ore by using 7 different brands of ore, and reported the effect of the oxygen potential and basicity of the melt. 9) Kimura et al investigated the effect of oxygen partial pressure in a state diagram for a CaO-SiO 2 -FeO-Fe 2 O 3 system, and noted that the liquid phase region expands at lower oxygen partial pressure.…”

“…Therefore, the holding time of the sintering bed in this 1473 K-1673 K temperature zone was measured. 8) Under the T2 condition, in which LNG injection was performed so as to obtain an LNG concentration of 0.4 vol%, the holding time at 1473 K-1673 K increased from 130 s to 190 s, or an increase of 60 s in comparison with the base condition T1. Under the T3 condition, in which the oxygen concentration was enriched to 25 vol%, the holding time at 1473 K-1673 K was 290 s; thus, the holding time at this temperature increased by 100 s in comparison with T2.…”

Modeling and Simulation of Iron Ore Sintering Process with Consideration of Granule Growth

“…[2][3][4][5] It has been proved useful in analyzing the sintering performance 6,7) and developing new technologies. [8][9][10] Besides, some researchers investigated the agglomeration phenomenon of granules and structural changes. 11,12) However, the process of granule growth was omitted in some previous mathematical models, which implies that agglomeration of particles was not considered.…”