Influence of Coke Reactivity Improved on High Temperature Properties of Iron-bearing Burden

Abstract

The influence of different reactivity coke on reduction, softening, melting and dropping properties of iron-bearing burden were studied by melting and dropping experiment, meanwhile reduction mechanism and softening-melting mechanism of stock column, as well as stock column pressure difference were also analyzed. The results show that reduction degree at 1 000°C increases, softening-melting start temperature and dropping temperature decrease, and melting temperature rises, when the coke reactivity increases from 24.76% to 56.28%. Softening and melting temperature interval increases, melting and dropping temperature interval reduces and stock column permeability is improved as the coke reactivity increased, which lead to softening-melting and dropping properties value of iron-bearing burden reducing. In addition, industrial experimental analysis shows that reducing agent rate (RAR) can be reduced by 8.26 kg/t using high reactivity coke (HRC) of 12%. Therefore, the appropriate increase of coke reactivity could improve stock column permeability and high temperature properties of iron-bearing burden, so as to reduce RAR.

A review of high-temperature experimental techniques used to investigate the cohesive zone of the ironmaking blast furnace

“…The coke breeze or graphite in the test can: (a) promote a more uniform distribution of reducing gas passing through the sample, (b) reduce the ferrous sample directly at high temperature and (c) decrease the melting temperature of metallic iron by offering carbon [91]. Some recent papers studied the influence of coke on the S&M properties of ferrous burden materials: for example, Sunahara et al [17] and Tuo et al [65] found that increasing coke reactivity could improve the permeability of the sample bed, while Ichikawa et al [92][93][94] reported that there is a minimum coke layer thickness to maintain BF permeability by charging coke within ferrous layers. In the S&M under load test, it is important to use similar coke conditions to routinely evaluate the quality of ferrous burden materials; however, it is also meaningful to vary the coke properties to explore the optimal coke conditions in the BF, including coke reactivity, size, ore/coke ratio and coke placement.…”

“…6 BF are a function of the position, with a slower temperature increase at the wall and a generally longer TRZ. In contrast, the experimental Crucible diameter (mm) 23 [32]; 24 [33,34]; 38 [35]; 42 [36]; 48 [37,38]; 60 [39,40]; 70 [41,42]; 120 [43] 26 [3,44]; 40 [8]; 60 [45,46]; 70 [47,48]; 75 [49]; 80 [50][51][52]; 85 [22,53]; 100 [54] 18 [14,55,56]; 26 [57][58][59][60]; 30 [24]; 36 [61]; 40 [16,62]; 48 [1,21,[63][64][65][66][67]; 50 [68,69]; 55 [70]; 60 [71,72]; 65 [73]; 70…”

“…[17] and Tuo et al. [65] found that increasing coke reactivity could improve the permeability of the sample bed, while Ichikawa et al. [92–94] reported that there is a minimum coke layer thickness to maintain BF permeability by charging coke within ferrous layers.…”

Effect of coke reactivity on softening-melting and dripping behaviors of sinter

“…The industrial test of 750 m3 blast furnace in Baosteel shows that increasing the dosage of high reactivity coke by 10% can lessens the reductant by 1.02 kg/t. Improving the coke reactivity appropriately can promote the reduction of iron-bearing burden [18].…”

Fundamental research on iron coke hot briquette – A new type burden used in blast furnace

“…Additionally, it was found that using formed iron coke in blast furnace could lower the temperature of thermal reserve zone and improve the shaft efficiency. Tuo et al 22 investigated the high temperature properties of iron-bearing burden with different reactivity coke charging. The results showed that the reduction degree of iron-bearing burden at 1000°C is accelerated with high reactivity coke charging.…”