Carbonaceous Material Properties and Their Interactions with Slag During Electric Arc Furnace Steelmaking
- PDF / 2,766,547 Bytes
- 12 Pages / 593.972 x 792 pts Page_size
- 40 Downloads / 296 Views
N
ELECTRIC arc furnaces (EAFs) are used for steel production, particularly when recycling scrap steel. More than 30 pct of global crude steel production is produced by EAFs. Electric current passes through electrodes creating the arcs which provide the primary energy source for melting scrap metal. Carbon can be charged along with scrap to partially substitute chemical energy for electrical energy when carbon is burned to CO and CO2. Besides providing energy, carbon can also be injected into molten slag to generate slag foam on top of liquid metal to protect the interior walls of the furnace against serious damage from intense arc radiation. Also, slag foaming can decrease heat loss during the melting process, resulting in lower electrode consumption and higher energy efficiency.[1,2]
XIAN-AI HUANG, KA WING NG, LOUIS GIROUX, and MARC DUCHESNE are with Natural Resources Canada, CanmetENERGY-Ottawa, 1 Haanel Drive, Ottawa, ON K1A 1M1, Canada. Contact e-mail: [email protected] Manuscript submitted November 27, 2018.
METALLURGICAL AND MATERIALS TRANSACTIONS B
Foamy slag is formed by CO and CO2 gas produced from the reduction of FeO in slag by carbon via a complex mechanism that depends on properties and quantities of slag and injected carbon. A number of studies have been carried out using various techniques to investigate the reduction kinetics of FeO in slag by solid carbon and dissolved carbon.[3–5] It was found that a gaseous layer of CO/CO2 is formed between the interface of solid carbon and slag, and also surrounds the carbon-iron metal drop as CO2 reacts with the carbon in the liquid iron and CO reacts with FeO in slag. Teasdale and Hayes proposed another mechanism for the reduction of solid FeO by graphite and coke, with liquid Fe-C droplets formed at the slag/carbon interface.[6] The formation of liquid Fe-C droplets improves the chemical reaction with carbon (in liquid-Fe) at the gas-liquid metal interface, resulting in significant gas generation and slag foaming. Currently, anthracite and coke are the main carbon sources used in EAFs. Due to its heavy dependence on carbon, EAF steelmaking contributes to greenhouse gas (GHG) emissions in the steel production sector. To reduce GHG emissions from EAF steelmaking, new technologies and materials should be developed to lower the consumption of fossil carbon. Substitution of fossil carbon with bio-char, a source of biocarbon, can achieve this and is an ongoing research theme for CanmetENERGY-Ottawa’s Metallurgical Fuels team.
Preliminary research on the use of bio-char in EAF operations was conducted in Europe and Australia. It was estimated that 27 to 37 pct of the total GHG emissions from EAFs could be reduced by the use of 100 pct biocarbon as charge and injection carbon.[7] As stated above, the slag foaming behavior is an important process aspect which must be taken into consideration when evaluating the use of biocarbon. The reduction reactions and slag foaming behavior depends not only on the physical and chemical properties of slag, but also on the car
Data Loading...
