Abstract
In the present research, charging carbon composite briquettes (CCB) in a blast furnace (BF) was investigated. The CCB used contained 29.70 wt.% Fe3O4, 39.70 wt.%, FeO, 1.57 wt.% iron, 8.73 wt.% gangue, and 20.30 wt.% carbon. Its reaction kinetics in BF was examined by nonisothermal tests and modeled. Thereafter, the influence of replacing 10% ore with CCB on BF performance was studied by numerical simulations. Results showed that the CCB reaction behavior in BF could be modeled using the previously proposed model under ags = 1900 m2·m−3. Numerical simulations on a BF with a production of 6250 t hot metal per day (tHM/day) showed that replacing 10% ore with CCB efficiently improved the BF operation for coke saving. In the CCB charging operation, the CCB reached a full iron-oxide reduction above the cohesive zone (CZ) and a carbon conversion of 85%. By charging CCB, the thermal state in the BF upper part was significantly changed while it was not influenced in the BF lower part; the ore reduction was retarded before the temperature reached 1073 K and was prompted after and the local gas utilization tends to increase above the CZ. By the CCB reduction above the CZ, BF top gas temperature was decreased by 8 K, the BF top gas utilization was increased by 1.3%, the BF productivity was decreased by 17 tHM/day, the coke rate was decreased by 52.2 kg/tHM, and ore rate was decreased by 101 kg/tHM. Considering the energy consumption of sintering and coking, charging the CCB could have a significant energy-saving and CO2-emission-reducing effect for BF iron making.
Highlights
The development of the economy and society is increasing the demand and production of iron and steel
The authors of the current study previously proposed to prepare carbon composite briquettes (CCB) using cold briquetting followed by heat treatment [24,25]
CCB prepared using this method under simulated blast furnace (BF) conditions and in actual BF have been elucidated and the results showed that the CCB reaction in BF includes five stages: reduction by BF gas, partial self-reduction with reduction by BF gas, full self-reduction partial self-reduction with gasification by BF gas and gasification by BF gas [25]
Summary
The development of the economy and society is increasing the demand and production of iron and steel. The authors of the current study previously proposed to prepare CCB using cold briquetting followed by heat treatment [24,25] By this method, various noncoking coals and iron-rich metallurgical dust could be used as raw materials, which could significantly reduce the CCB cost. Simulations on BF operations with CCB charging have been conducted by Chu et al [30] and Yu et al [31] In their studies, the reaction model of CCB was significantly simplified and could not reflect the real behavior in BF, which may lead to some misunderstanding in interpreting the influence of CCB charging on BF performance. Thereafter, BF operation with replacing 10% ore by CCB was investigated by numerical simulations
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