Progress in the kinetics of slag-metal-gas reactions, past present and future

Coley, Kenneth S.

doi:10.2298/jmmb121220017c

Cited by 15 publications

(7 citation statements)

References 36 publications

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“…Several groups have built specialized equipment and combined powerful techniques to investigate the decarburization of individual droplets. Molloseau and Fruehan [60] and Coley et al [61][62][63][64] have published a plethora of studies making use of X-ray radiography techniques combined with a vertical tube furnace. These researchers have made observations on the effects of carbon content, iron oxide, sulfur, temperature, and other parameters on the rate of decarburization that a single metallic droplet undergoes.…”

Section: Decarburization-driven Bloated Dropletsmentioning

confidence: 99%

Basic Oxygen Steelmaking Slag: Formation, Reaction, and Energy and Material Recovery

Spooner

et al. 2021

steel research int.

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The basic oxygen steelmaking (BOS) process produced over 70% of the global crude steel in 2018, [1] generating 100 to 150 kg of slag ("BOS slag") for every tonne of crude steel produced. BOS slag, a product of hot metal element (e.g., Si, Mn, Fe, P) oxidation and flux (e.g., lime, dolomite) dissolution, plays a critical role in the production of high-quality crude steel.All elements present in the hot metal charged in the BOS converter are thermodynamically very unstable with respect to their oxides when exposed to the oxygen jet at the BOS operating temperatures. Thus, carbon, silicon, manganese, phosphorus, and the iron itself all tend to oxidize very rapidly to form CO (or CO 2 ), SiO 2 , MnO, P 2 O 5 , and FeO (or Fe 2 O 3 ), respectively. In the BOS practice, large quantities of iron and silicon are initially oxidized to give a liquid, predominantly binary, FeO-SiO 2 slag, which floats on top of the metal pool. Usually lime (CaO) is rapidly added to "neutralize" this acid FeO-SiO 2 slag and produce a "basic" multicomponent FeO-SiO 2 -CaO-MnO-Al 2 O 3 -MgO-P 2 O 5 slag. This basic slag produces the correct partition of metalloids, particularly phosphorus, between the slag and metal and also protects the basic vessel lining (usually magnesite, MgO). Over the entire blowing period of the BOS process, this basic slag is emulsified with a large amount of gas bubbles and metal droplets, and the gas-slag-metal droplet reactions control the element transfer between the steel and slag (e.g., phosphorus removal and reversion) and subsequently the productivity and crude steel quality, which greatly attracts great interest from academics to understand the transient phenomena in the gas-BOS slag-metal droplet system. After completing its refining function in the BOS process, the hot BOS slag is poured into a slag pot. The BOS slag was considered a waste in old times but now as a secondary resource because it contains a large amount of thermal energy (temperature up to 1700 C), chemical energy (metallic and low-valence metallic oxides), and valuable materials (e.g., iron oxides).The behavior of BOS slag inside the BOS vessel, e.g., formation and reaction with gas and metal droplets, is still not clear and its recycling, including energy and material recovery, has always been challenging. This article introduces some BOS-slag-related research conducted by the present authors, in addition to a critical review of relevant research reported in the literature. It covers the topics of lime dissolution (slag formation), high-temperature-behavior interrogation through in situ observation, slag-metal droplet reaction mechanisms (spontaneous emulsification), and recovery of energy and materials from the molten BOS slag. This article aims to provide state-of-the-art understanding on relevant research topics and point out new research directions.

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Section: Decarburization-driven Bloated Dropletsmentioning

confidence: 99%

Basic Oxygen Steelmaking Slag: Formation, Reaction, and Energy and Material Recovery

Spooner

et al. 2021

steel research int.

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“…Two prominent laboratories in the field of pyrometallurgy have produced a series of well-respected journal publications in this immediate area. [49,69,76] They use an experimental setup where a vertical tube furnace is positioned between X-ray radiography equipment. These studies have been invaluable in their findings of gas phase phenomena such as the generation of a ''gas halo'' and ''bloated droplets'' during the decarburization reaction.…”

Section: Gas Phase Production Effects On Free Steel Dropletsmentioning

confidence: 99%

“…The final group of underpinning work supporting the advancements of this article are the modern in situ observations, which began with Molloseau and Fruehan [47] and were built upon by the collection of researchers working with Chen and Coley [48] and Coley. [49] These researchers used X-ray fluoroscopy and radiography to visualize the movement of metal droplets at high temperature during reaction and found the rate at which droplets emit gaseous reaction product, oscillate in size, and density, ultimately providing proof that droplets may exist for an extended period of time within gas/slag/metal emulsions contributing extensively to the overall effective interfacial reaction area that exists within steelmaking processes.…”

Section: Introductionmentioning

confidence: 99%

Hidden Phenomena During Transient Reaction Trajectories in Liquid Metals Processing

Spooner

Sridhar

2020

Metall Mater Trans B

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The transient trajectory taken for a system striving toward equilibration has consequences on the rate of processes and on the chemical and physical state of products in metallurgical processes. A case study approach to recent advancements in liquid steel processing is given. A combination of techniques and knowledge developed is given as a targeted showcase of the authors' contributions to the understanding of liquid metal droplet reactions and their contribution to the large-scale production processes within the steel industry. Examples relevant to novel ironmaking technologies, oxygen steelmaking, ladle metallurgy, and continuous casting are discussed, showing the range of processes that benefit from greater understanding in this area. This article considers specifically the reaction of liquid ferrous droplets, immersed in molten oxides, involving key alloying components, including phosphorus, aluminum, and carbon. The studies use high-temperature-confocal scanning laser microscopy (HT-CSLM), X-ray computed tomography (XCT), phase-field modeling, and in situ limited angle X-ray imaging. These techniques have seen significant development over recent years, and the combination of these powerful tools reveals the occurrence of spontaneous emulsification driven by chemical reaction (in the case of oxygen/phosphorus/aluminum reactions) and gas-phase formation (in the case of decarburization) both internally and externally to a steel droplet. A key finding is that the interfacial area pertinent for the heterogenous reactions to occur changes considerably (by up to an order of magnitude) depending on the chemical driving force. Additional key findings include the shift between preferential internal and external gas nucleation during decarburization, an inflection point of behavior as to whether or not spontaneous emulsification will occur (within the study discussed, this is between 3 and 4 wt pct Al) and the pathway of perturbation growth through which spontaneous emulsification occurs, including the physical maxima a perturbation will grow to before breaking away from the parent droplet.

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“…For carbothermic reaction slag basicity have significant role in terms of proper progress of the reactions and element distribution in metal, slag and gaseous phase [11] The slag basicity in carbothermic reactions is adjusted primarily by amounts of silica sand and lime. In aluminothermic reactions slag viscosity has significant role primarily due to the separation of metal and slag.…”

Section: Figure 1 Algorithm For Modeling Of Materials and Energy Balancementioning

confidence: 99%

“…In aluminothermic reactions slag viscosity has significant role primarily due to the separation of metal and slag. Slag viscosity directly dependent on the temperature [10,11]. Adjusting the temperature of reaction is possible through addition of sodium nitrate in order raise, or iron chips in order to lower the temperature.…”

Section: Figure 1 Algorithm For Modeling Of Materials and Energy Balancementioning

confidence: 99%

Semi-empirical software for the aluminothermic and carbothermic reactions

Gavrilovski¹,

Manojlović²,

Kamberović³

et al. 2014

Metall Mater Eng

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Understanding the reaction thermochemistry as well as formatting the empirical data about element distribution in gas-metal-slag phases is essential for creating a good model for aluminothermic and carbothermic reaction. In this paper modeling of material and energy balance of these reactions is described with the algorithm. The software, based on this model is basically made for production of high purity ferro alloys through aluminothermic process and then extended for some carbothermic process. Model validation is demonstrated with production of FeTi, FeW, FeB and FeMo in aluminothermic and reduction of mill scale, pyrite cinders and magnetite fines in carbothermic process.

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Progress in the kinetics of slag-metal-gas reactions, past present and future

Cited by 15 publications

References 36 publications

Basic Oxygen Steelmaking Slag: Formation, Reaction, and Energy and Material Recovery

Basic Oxygen Steelmaking Slag: Formation, Reaction, and Energy and Material Recovery

Hidden Phenomena During Transient Reaction Trajectories in Liquid Metals Processing

Semi-empirical software for the aluminothermic and carbothermic reactions

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