Realization of Bio-Coal Injection into the Blast Furnace

• Published in: Metals (Basel ) Vol. 14; no. 9; p. 969
• Main Authors: Sundqvist Ökvist, Lena, Lundgren, Maria, From, Lars-Erik, Eck, Joakim, Kjellberg, Ma, Ahmed, Hesham
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.09.2024
• Subjects: Ammonia; bio-coal; Blast furnaces; Briquets; Brittleness; Calorific value; Carbon dioxide; Charcoal; CO2 emission; Coal; Coal injection; Coke fired furnaces; Combustion efficiency; Conveying; Devolatilization; Dust; Fluid flow; Grinding; injection; Iron and steel industry; Metallurgy; Moisture content; Natural gas; Process Metallurgy; Processmetallurgi; Pulverized coal; reducing agent; Steel industry; Steel making; Steel production; Tuyeres; Sweden; India; Brazil; Netherlands; United States > US; Finland
• ISSN: 2075-4701; 2075-4701
• DOI: 10.3390/met14090969

The steel industry accounts, according to the International Energy Agency, for ~6.7% of global CO[sub.2] emissions, and the major portion of its contribution is from steelmaking via the blast furnace (BF) route. In the short term, a significant reduction in fossil CO[sub.2] emissions can be achieved through the introduction of bio-coal into the BF as part of cold bonded briquettes, by injection, or as part of coke. The use of bio-coal-containing residue briquettes was previously demonstrated in industrial trials in Sweden, whereas bio-coal injection was only tested on a pilot scale or in one-tuyere tests. Therefore, industrial trials replacing part of the pulverized coal (PC) were conducted. It was concluded that the grinding, conveying, and injection of up to 10% of charcoal (CC) with PC can be safely achieved without negative impacts on PC injection plant or BF operational conditions and without losses of CC with the dust. From a process point of view, higher addition is possible, but it must be verified that grinding and conveying is feasible. Through an experimentally validated computational fluid flow model, it was shown that a high moisture content and the presence of oversized particles delay devolatilization and ignition, lowering the combustion efficiency. By using CC with similar heating value to PC, compositional variations in the injected blend are not critical.