Experimental and Numerical Investigation of Reaction Behavior of Carbon Composite Briquette in Blast Furnace

Huiqing Tang,Tao Rong,Yanjun Sun

doi:10.3390/met10010049

Abstract

The application of carbon composite briquette (CCB) is considered to be an efficient method for achieving low-energy and low-CO2-emission blast furnace (BF) operations. In this research, a combined experimental and numerical study was conducted on the CCB reaction behavior in BF. The CCB used in this study had a composition of 20.10 wt.% carbon, 29.70 wt.% magnetite, 39.70 wt.% wüstite, and 1.57 wt.% metallic iron. Using the prepared CCB samples, isotherm reduction tests under a simulated BF atmosphere (CO-CO2-N2) were conducted and a reaction model was developed. Subsequently, the reaction behavior of CCB along the mid-radial solid descending path in an actual BF of 2500 m3 was analyzed by numerical simulations based on the experimental findings and the previous results of comprehensive BF modeling. The results of the experiments showed that the CCB model predictions agreed well with the experimental measurements. With respect to the BF, the results of the numerical simulations indicated that, along the path, before the CCB temperature reached 1000 K, the CCB was reduced by CO in the BF gas; when its temperature was in the range from 1000 to 1130 K, it underwent self-reduction and contributed both CO and CO2 to the BF gas; when its temperature was above 1130 K, it only presented carbon gasification. Moreover, these results also revealed that the reduction of iron oxide and the gasification of carbon inside the CCB proceeded under an uneven mode. The uneven radial distribution of the local reduction fraction and local carbon conversion were evident in the self-reducing stage of the CCB.

Highlights

In the foreseeable future, the traditional manufacturing route (i.e., blast furnace (BF) ironmaking and basic oxygen furnace (BOF) steelmaking) will continue to be predominant methods for producing iron and steel across the world [1]. These processes are well-established and highly efficient, they face challenges related to lowering energy consumption and minimizing CO2 emissions that are needed to create a more efficient and sustainable iron and steel industry
75%–80% of the total energy consumption and it generates the largest amount of CO2 emissions [2,3]
Finding ways for the BF industry to conform to these environmentally standards is crucial

Summary

Introduction

In the foreseeable future, the traditional manufacturing route (i.e., blast furnace (BF) ironmaking and basic oxygen furnace (BOF) steelmaking) will continue to be predominant methods for producing iron and steel across the world [1]. These processes are well-established and highly efficient, they face challenges related to lowering energy consumption and minimizing CO2 emissions that are needed to create a more efficient and sustainable iron and steel industry. Using CCB as a partial charge in a BF offers the benefits of (1) less sintering and coking processes [5,6], (2) the effective use of non-coking coal and iron-bearing dust and sludge [7], (3) faster reduction of iron oxide [8,9], and (4) the decrease of BF energy consumption [10]

Objectives

Methods

Results

Conclusion