Hydrometallurgical Cleaner Production Technology, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, , China

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1 Advanced Materials Research Online: ISSN: , Vols , pp doi: / Trans Tech Publications, Switzerland CO 2 emissions from BF-BOF and EAF steelmaking based on material flow analysis Yinjiao Li 1, 2, a, Wenqing Xu 1, b, Tingyu Zhu 1, c, Feng Qi 1, d Tiebing Xu 3, e, Zhen Wang 1, f 1 Research Center for Process Pollution Control, National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, , China 2 Graduate University of Chinese Academy of Sciences, Beijing, , China 3 Hebei Provincial Environmental Scientific Research, Shijiazhuang, , China a liyinjiao09@gmail.com, b wqxu@mail.ipe.ac.cn, c tyzhu@mail.ipe.ac.cn, d fqi@mail.ipe.ac.cn, e xtb@hb12369.net, f wangz@mail.ipe.ac.cn Keywords: Carbon dioxide, Emission, Material Flow Analysis, Iron and Steel Making Abstract. In order to calculate the amount of CO 2 emissions from the iron and steel making in China, carbon flows in two iron and steel enterprises were investigated with Material Flow Analysis, through the production data and sampling of materials from each enterprise in this paper. Results show that the main carbon sources of CO 2 emissions in blast furnace-basic oxygen furnace (BF-BOF) steelmaking are fossil fuel, and fossil fuel in electricity furnace (EAF) steelmaking account for 33% of the total carbon sources; The amount of CO 2 emission of per ton crude steel from the BF-BOF steelmaking and EAF steelmaking is and 46.6 kg, respectively. Introduction The global climate change caused by CO 2 has become a hot issue worldwide. CO 2 emissions from iron and steel industry are a serious problem, because of the heavy relying on fossil fuels as an energy source. CO 2 discharged from the iron and steel industry accounts for around 9.2% of the total CO 2 emissions in China, about 30% of which originates from the industrial sector [1]. China has committed to cut its carbon emission intensity by 40% to 45% per GDP unit from its 2005 level by year 2020, particularly as China s iron and steel industry is facing increasing demands to cut down on their CO 2 emissions. Research on data of dust, sulfur dioxide and nitrogen oxides emited from iron and steel industry in China is comprehensive and systematic. However, research on data of CO 2 emissions from iron and steel industry in China is less. CO 2 emissions from coal reduction extreme system (COREX) have been compared with blast furnace iron making system and COREX was found to contribute little to CO 2 emission reduction, which is and kg per ton crude steel, respectively [2]. The impact of different sources and structures of raw materials and fuels on CO 2 emission in the blast furnace process and electric furnace process has been analyzed, and CO 2 emissions have been estimated [3]. The carbonaceous flows in iron and steel making have been analyzed and CO 2 emissions per ton steel through the BF-BOF steelmaking and EAF steelmaking were 2149 kg and 585 kg, respectively [4]. However, research on carbon flows from each process of iron and steel making is few. In this paper, two different types of enterprises were chosen, and one is an enterprise of BF-BOF steelmaking and the other is an enterprise of EAF steelmaking. The amount of material used/produced is surveyed and sampling of materials is done through field investigation. Then carbon flows of each process of two steel works are analyzed through material flow analysis, and CO 2 emissions from each process are calculated. All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, (ID: , Pennsylvania State University, University Park, USA-10/05/16,19:30:19)

2 Advanced Materials Research Vols Methods Material flow analysis (MFA) is a systematic assessment of the flows and stocks of material within a system defined in space and time. The results of MFA can be controlled by connecting the sources, the pathways, and the intermediate and final sinks of a material, because of the law of the conservation of matter [5]. The major types of steelmaking route in China are the BF-BOF and EAF steelmaking. In 2009, the amount of crude steel from BF-BOF and EAF steelmaking route account for 90.3% and 9.6% of the total crude steel production, respectively. BF-BOF steelmaking route is comprised by sintering, pelletizing, coking, blast furnace ironmaking and basic oxygen furnace steelmaking, and carbon flows of BF-BOF steelmaking route are shown in Fig.1. Carbon flows of EAF steelmaking route are shown in Fig.2. CO 2 emissions from sintering and pelletizing are mainly from fuel consumption and decomposition of the fusingagent, which can be calculated through carbon flow of flue gas from sintering or pelletizing. CO 2 emissions from coking, blast furnace ironmaking and basic oxygen furnace steelmaking are mainly from their gas burned to provide heat of combustion and gas discharge, which can be calculated through carbon flows of gas consumption and discharge. In coking, coke oven gas (COG) is used for providing heat of dry distillation by flamed in combustion chamber; in blast furnace ironmaking, blast furnace gas (BFG) is used for providing heat of hot blast stove in combustion chamber; in basic oxygen furnace steelmaking, basic oxygen furnace (BOG) is used for providing energy of roast basic oxygen furnace [6]. CO 2 emissions from arc furnace steelmaking are from consumption of steel scrap, fusingagent, and electrode, and so on, which can be calculated through carbon flows of flue gas from arc furnace steelmaking [7]. Results Carbon flows of BF-BOF and EAF steelmaking are shown in Fig.1 and Fig.2, respectively. Fig.1 Carbon flows of per ton product in BF-BOF steelmaking

3 5014 Advances in Environmental Science and Engineering Fig.2 Carbon flows of per ton product in EAF steelmaking The CO 2 emissons of per ton crude steel in BF-BOF and EAF steelmaking are kg and 46.6 kg, respectively, as shown in Table 1. Table 1 CO 2 emissions of per ton crude steel in the process of iron and steel making Production process CO 2 emisisons of per ton product kg CO 2 / ton crude steel ratio CO 2 emisisons of per ton crude steel kg CO 2 / ton BF-BOF steelmaking Sintering Pelletizing Coking Blast furnace ironmaking Basic oxygen furnace steelmaking Total of CO 2 emissions from BF-BOF steelmaking EAF steelmaking Arc furnace steelmaking Total of CO 2 emissions from EAF steelmaking The crude steel ratio is the quantity of consumption of product in the production of one ton crude steel. 2 In sintering and pelletizing, the heating gas is BFG. Discussion Carbon flows of each process in iron and steel making are different, as shown in Fig.1 and Fig.2. In sintering, carbon sources include coal and fine coke (solid fuel), BFG (ignites gas), fusingagent (limestone and dolomite, etc.) and iron material (iron ore and dust, etc.), and carbon flow of each part accounts for 65.5%, 14.5%, 18.0% and 2.0% of total carbon sources. Among them, solid fuel and ignites gas is a fossil fuel. Carbon sinks include sinter and flue gas, and carbon flow of each part accounts for 2.1% and 97.9% of total carbon sinks. Moreover, dust and sinter return are used for recycling in sintering. In pelletizing, carbon sources include BFG (burning gas) and iron ore, and carbon flow of each part accounts for 96.6% and 3.4%, respectively. Carbon sinks include pellet and flue gas, and carbon flow of each part accounts for 4.7% and 95.3%, respectively. In addition, dust and pellet return are used for recycling in pelletizing or sintering. In coking, carbon source is coking coal. Carbon sinks include coke, fine coke (unqualified coke), benzol, coal tar, dust and COG (gas discharge, heating and sent to other process), and carbon flow of each part accounts for 76.6%, 4.9%, 1.0%, 2.4%, 2.2% and 10.9%, respectively. In blast furnace ironmaking, carbon sources include coke, coal (coal injection in blast furnace) and sinter/pellet, and carbon flow of each part accounts for 69.1%, 30.3% and 0.6%, respectively. Carbon sinks include molten iron, slag, dust and BFG (gas discharge, heating and sent to other process), and carbon flow of each part accounts for 10.1%, 0.1%, 0.9% and 88.9%, respectively.

4 Advanced Materials Research Vols In basic oxygen furnace steelmaking, carbon sources include molten iron, steel scrap, lump ore and fusingagent, and carbon flow of each part accounts for 94.1%, 0.2%, 0.2% and 5.4%, respectively. Carbon sinks include molten steel, slag, dust, and BOG (gas discharge, heating and sent to other process), and carbon flow of each part accounts for 23.4%, 0.2%, 0.5% and 75.9%, respectively. In arc furnace steelmaking, carbon sources include steel scrap, fusingagent, fuel, carburetant and electrode, and carbon flow of each part accounts for 50.2%, 16.9%, 3.5%, 13.0% and 16.5%, respectively. Among them, fossil fuel includes fuel, carburetant and electrode. Carbon sinks include molten steel, slag, dust and flue gas, and carbon flow of each part accounts for 43.3%, 1.3%, 0.4% and 55.0%, respectively. From carbon flows analysis in iron and steel making, the carbon sources are mainly from fossil fuel. Carbon sources from fossil fuel in sintering account for 80% of the total carbon sources; in basic oxygen furnace steelmaking, fossil fuel is hardly consumed because of negative steelmaking technologies. Carbon sources from fossil fuel in arc furnace steelmaking account for 33% of the total carbon sources. In other processes, the carbon sources are almost entirely from fossil fuel. CO 2 emissions per ton crude steel from BF-BOF steelmaking are much more than that of EAF steelmaking, because it needs to consume large amounts of energy in the reduction reaction from iron oxide to iron. Among them, the CO 2 emissions of blast furnace iron making, sintering and coking account for 54%, 29% and 8% of the total CO 2 emissions per ton crude steel from BF-BOF steelmaking, as shown in Table 1. Conclusion The carbon sources of CO 2 emissions in BF-BOF steelmaking are mainly from fossil fuel. And carbon sources from fossil fuel in EAF steelmaking account for 33% of the total carbon sources. CO 2 emissions per ton crude steel in BF-BOF and EAF steelmaking are kg and 46.6 kg, respectively. References [1] Z.J. Huang, X. Ding, H. Sun, S.Y. Liu, Identification of main influencing factors of life cycle CO 2 emissions from the integrated steelworks using sensitivity analysis, J Clean Prod. Vol. 18 (2010), p [2] C.Q. Hu, X.W. Han, Z.H. Li, C.X. Zhang, Comparison of CO 2 emission between COREX and blast furnace iron-making system, J Environ Sci-China.Vol. 21 (2009), p [3] C.X. Zhang, F.Q. Shang guan, C.Q. HU, Steel process structure and its impact on CO 2 emission, Iron and Steel. Vol. 45 (2010), p1-6 (In Chinese). [4] F.Q. Shang guan, C.X. Zhang, C.Q. Hu, Estimation of CO 2 emissions in Chinese steel industry, China Metallurgy.Vol. 20 (2010), p (In Chinese). [5] P. H. Brunner, H. Rechberger, Practical handbook of material flow analysis, Lewis Publishers, Florida, [6] G Sheng, Y.G. Sun, H.Y. Xu, T.Y. Jia, L.N. He, Study on carbon flow moldel and CO 2 emissions in iron and steel process, China Metallurgy. Vol. 45 (2011), p1-6 (In Chinese). [7]Y. Sakamoto, Y. Tonooka, Estimation of CO 2 emission for each process in the Japanese steel industry: a process analysis, Int J Energy Res. Vol. 24 (2000), p

5 Advances in Environmental Science and Engineering / CO 2 Emissions from BF-BOF and EAF Steelmaking Based on Material Flow Analysis / DOI References [7] Y. Sakamoto, Y. Tonooka, Estimation of CO2 emission for each process in the Japanese steel industry: a process analysis, Int J Energy Res. Vol. 24 (2000), pp / X( )24:7<625::AID-ER616>3.0.CO;2-R