Influence of Coke Reactivity on Softening‐Melting Dropping Behavior of Iron‐Bearing Burden

Abstract

The influences of the different reactivity cokes on softening-melting dropping of iron-bearing burden were studied by melting-dropping experiment. The pressure difference and shrinkage rate of burden layer, as well as the burden reduction degree at the same temperature were also analyzed. The results show that the softening and melting starting temperature reduces from 1200 to 1160 8C, and the softening and melting end temperature increases from 1290 to 1320 8C, while the melting ending temperature is unchanged and the dropping temperature of molten iron reduces from 1413 to 1380 8C, when the coke reactivity increases from 24.76 to 65.16%. Softening-melting temperature interval increases with the improvement of coke reactivity based on the above temperatures change, meanwhile, melting temperature interval and the dropping temperature interval (DT 3 ¼ T d À T P ) reduces, respectively. In addition, the shrinkage rate of charge column decreases and the permeability of charge column get better when the coke reactivity increases from 24.76 to 65.16%. The softening-melting and dropping characteristic evaluation of iron-bearing burden reduces with the improvement of coke reactivity. Appropriately increasing coke reactivity may improve charge column permeability and increase softening-melting and dropping characteristic of iron-bearing burden, therefore, it is of great significance for saving energy and reducing consumption of blast furnace smelting.

Effect of Charcoal and Kraft-Lignin Addition on Coke Compression Strength and Reactivity

“…Despite the general standard of using low reactivity coke in blast furnaces, in recent years a significant research interest has been shown towards the utilization of highly-reactive coke [36][37][38][39][40]. The interest for using high reactivity coke arises from theoretical considerations, which show that a decrease in the equilibrium temperature between reducing gas and wüstite (Fe 1−x O) in the BF shaft can increase the gas utilization rate (CO 2 /CO-ratio), resulting in lower fuel consumption [38], which would bring significant economic savings.…”

“…In a Japanese Muroran BF, the use of high-reactivity coke decreased the fuel rate by 10 kg/thm (roughly 2%) [37]. High reactivity coke could also improve the softening and melting properties of iron ore [40].…”

Coke Reactivity in Simulated Blast Furnace Shaft Conditions

“…This can lead to small changes to the gas composition through the reversible water-gas shift reaction (Eq. [1]); however, the feed gas was always kept constant independent of the test temperature.…”

“…It also impacts the softening and melting properties of iron ore and permeability resistance of the BF. [1] Coke is gasified in the blast furnace shaft by the so-called solution-loss reactions with CO 2 and H 2 O. Solution-loss reactions in the blast furnace are limited by the partial pressure of oxygen in the gas, which is increased as a result of the iron ore reduction reactions in the shaft. It has been said that the total amount of coke solution loss is largely independent of coke reactivity [2,3] and is generally reported to vary between 25 and 30 pct depending on operating conditions.…”

A review on nut coke utilisation in the ironmaking blast furnaces

“…The concept of active nut coke and passive regular coke usage in blast furnace has been introduced in recent past. [22][23][24][25][26][27][28] The reactivity of nut coke is enhanced for its preferential dissolution in the mixed burden layer. The reactivity of nut coke can be enhanced by the addition of Fe 2 O 3 , Fe 3 O 4 and CaO as a dopant.…”