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Metal–Crucible Interactions
Published in Nagaiyar Krishnamurthy, Metal–Crucible Interactions, 2023
The blast furnace is a vertical shaft furnace in which air introduced under pressure into the bottom of the furnace burns the fuel, usually coke, present in a mixture of metallic ore, coke and flux fed into the top. The ensuing smelting reactions produce liquid metal and molten slag, which collect in the hearth at the bottom and are recovered. Blast furnaces are used to produce pig iron from iron ore for subsequent processing into steel, and they are also used for production of lead, copper and other metals. Intense combustion is maintained by the current of air under pressure.
Water/Wastewater Conveyance
Published in Frank R. Spellman, Handbook of Water and Wastewater Treatment Plant Operations, 2020
A ferrous metal is one that contains iron (elemental symbol Fe). Iron is one of the most common metals but is rarely found in nature in its pure form. Comprising about 6% of the earth’s crust, iron ore is actually in the form of iron oxides (Fe2O3 or Fe3O4). Coke and limestone are used in the reduction of iron ore in a blast furnace where oxygen is removed from the ore, leaving a mixture of iron and carbon and small amounts of other impurities. The end product removed from the furnace is called pig iron—an impure form of iron. Sometimes the liquid pig iron is cast from the blast furnace and used directly for metal castings; however, the iron is more often remelted in a furnace, to further refine it and adjust its composition (Babcock & Wilcox, 1972).
Metals
Published in Ronald M. Scott, in the WORKPLACE, 2020
Iron is the fourth most abundant element in the earth’s crust. Most iron ore, largely taconite, comes from open pit mines in Minnesota and northern Michigan. Metallic iron is produced in a blast furnace into which mixtures of ore, limestone, and coke are fed. The carbon of the coke reduces the iron oxide to the free metal, which is poured into ingots.
A Case Study on Large-scale Grate-kiln Production of Fluxed Iron Oxide Pellets: Zhanjiang Pelletizing Plant of BaoSteel
Published in Mineral Processing and Extractive Metallurgy Review, 2019
Tiejun Chen, Lisheng Liang, Shiming Tang, Yanhong Luo, Yunliang Zhao, Shaoxian Song
Based on the slag basicity required by blast furnace smelting, limestone powder was used to increase basicity in the finished pellets. Studies showed that adding the correct amount of limestone into hematite can improve its pelletizing performance and the quality of resulting green pellets. For fluxed hematite pellets produced with finely ground limestone, the limestone component can absorb heat in the preheating stage, reducing the pellets’ internal temperature, which lowers their strength during preheating. Conversely, the CaO and Fe2O3 will react under solid state to produce semi-calcium ferrite slag phases and small amounts of liquid phases that facilitate microcrystalline connections between iron oxides. Such slag phases can increase the strengths of pellets during roasting and after reduction, and decrease their roasting temperature (Onoda et al. 1981; Panigrahy et al. 1990). The pellets fluxed with limestone also perform better in smelting than acidic pellets, which improves the output of blast furnaces, prolongs furnace life, and lowers the coke ratio and silicon content in the molten iron (Schönert 1991).
Recent trends in the treatment of cyanide-containing effluents: Comparison of different approaches
Published in Critical Reviews in Environmental Science and Technology, 2023
Ludmila Martínková, Pavla Bojarová, Anastasia Sedova, Vladimír Křen
Some other industries produce cyanide as a byproduct. During the production of coke (coal pyrolysis at up to 1,200 °C), HCN passes into coke oven gas along with H2S, ammonia, and organic material. Cooling of coke oven gas produces “coal liquor,” which becomes “raw coking effluent” after the separation of tar and ammonia (Kwiecińska-Mydlak et al., 2019). In 2016, nearly 650 Mt of coke were produced worldwide (Ghosh et al., 2022). The main consumers of coke are iron and steel plants (Kwiecińska-Mydlak et al., 2019). Coke is used, e.g., for smelting iron ore in blast furnaces at over 1,000 °C, to give crude iron. Cyanides are also formed at this stage. This occurs through the reactions between carbon, nitrogen, and alkali metals (Mondal et al., 2021).
Influence of TiO2 addition on the structure and metallurgical properties of coke
Published in International Journal of Coal Preparation and Utilization, 2021
Shuxing Qiu, Shengfu Zhang, Rongjin Zhu, Yue Wu, Guibao Qiu, Jie Dang, Liangying Wen, Meilong Hu, Chenguang Bai
In an iron making blast furnace, coke plays a critical role in providing carbon monoxide for reduction, carbon to carburization the iron, and supporting the furnace stack to keep it permeable (Gupta et al. 2013). Metallurgical coke is expensive, and it is the aim of every steel works to lower the amount of coke required to produce a tonne of pig iron. Metallurgical coke is predominantly organic carbon with minor inorganic minerals scattered in the carbon matrix (Ghosh et al. 2017). The properties of metallurgical coke, related to its performance in the blast furnace, is a strong function of parent coal properties, and they include rank, maceral composition, and mineral matter types. These together with coking conditions determine the composition of the mosaic microtexture and, consequently, its macro and bulk properties such as strength and reactivity (Grigore et al. 2006; Song et al. 2017). More specifically, it has been shown that these bulk properties are strongly dependent on the isotropic carbon content, the size and shape of the anisotropic carbon units, and the interfaces between the textural components together with porosity (Sato, Patrick, and Walker 1998). Coking conditions such as temperature (Qiu et al. 2007), time (Grigore et al. 2007), and heating rate (Wiktorsson and Wanzl 2000) play an important role in determining coke structure. Generally, coking research has focused on the effect of coal rank, maceral composition and coking conditions on the coke properties. While this is important, it is also clear that the mineral matter in coke affects its degradation behavior in a blast furnace (Vogt and Depoux 1990), which means that a good quality feed coke may not give the expected furnace performance because of the presence of a certain mineral in its structure.