Crystallization Behavior of Liquid CaO-SiO2-FeO-MnO Slag in Relation to Its Reaction with Moisture

Li, Juncheng; Bhattacharjee, D.; Hu, Xiaojun; Zhang, Mengjie; Sridhar, Seetharaman; Li, Zushu

doi:10.1007/s11663-019-01595-z

Cited by 10 publications

(3 citation statements)

References 51 publications

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“…Recently a novel process was developed by the present authors [140][141][142] to recover thermal energy from molten BOS slag as syngas and hot gas, and recover valuable metals (Fe, Mn) in the form of magnetite by controlling the crystallization of the BOS slag after reacting the molten BOS slag with moisture. This process is based on the reaction of the molten steelmaking slag with the moist atmosphere (Figure 9).…”

Section: A Novel Process To Recover Energy and Materials From Bos Slagmentioning

confidence: 99%

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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: A Novel Process To Recover Energy and Materials From Bos Slagmentioning

confidence: 99%

“…This novel process has been extensively studied in terms of the fundamental understanding of the reaction mechanisms, effects of processing parameters on hydrogen harvesting, and optimal conditions for controlled crystallization of targeted phases. [140][141][142]…”

Section: A Novel Process To Recover Energy and Materials From Bos Slagmentioning

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 environment furnace is able to provide a maximum temperature up to 1700°C with heating and cooling rates of up to 20 and 100 K/s (helium-forced cooling), respectively, [31] obtained by infrared radiation heating, which helps to avoid high-energy beam-local ionization. The furnace is compatible with inert gas (Ar, N 2 ), reductive gas (H 2 , CH 4 ), oxidizing gas (CO 2 , air, O 2 , H 2 O), and vacuum [32] to simulate the high-temperature behavior of the gas-liquid-solid reaction under a range of environmental conditions. The optical acquisition unit is composed of a laser generator for the violet laser source with a wavelength of 405 nm, an optical focusing control system, and a CCD camera that is used to image the sample behavior in the environment furnace through the quartz window.…”

Section: B In-situ Observation Of the Melting And Solidification Phenomena Of 316l Powdersmentioning

confidence: 99%

Effect of Surface Oxides on the Melting and Solidification of 316L Stainless Steel Powder for Additive Manufacturing

Yang

Gao

Tang

et al. 2021

Metall Mater Trans A

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Surface oxidation of metallic powders may significantly affect their melting and solidification behavior and limit their service life in the additive manufacturing (AM) process. In the present work, three levels of surface oxide concentration were prepared on AM-grade 316L stainless steel powders, and their melting and solidification behavior was systematically studied through in-situ observation, advanced characterization, phase-field modeling, and theoretical analysis. Si, Mn, and Cr participated in the oxidation reaction in powder with low and medium oxygen contents, whereas Fe was involved in the oxidation reaction for the powder samples with high oxygen content. A higher full melting temperature is observed to lead to an integrated melt pool in the melting of the highly oxidized powder, which is due to the reduced permeability produced by the oxide cage effect. For the droplet samples prepared from high oxygen powders, the inclusion with increased volume fraction and coarsened size is attributed to the agglomeration of inclusion particles with the residual oxide in the melt. In the high oxygen powder fusion scenario, an undesired coarse columnar grain structure with a high aspect ratio is formed in the current nonequilibrium solidification process, and a consistent microstructure is predicted using solidification conditions with a high cooling rate and high thermal gradient similar to the conventional AM process. In contrast, fine equiaxed grains in the experiment and slim columnar grains with a small aspect ratio in the phase-field simulation are obtained for the low oxygen powder condition. This study illustrates the effect of powder oxide from a processing aspect and provides insight into the importance of improving the service life of powder feedstock by effectively reducing the surface oxidation process on the powder surface.

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Melting and Solidification Behaviors of the Copper Slags with Different CaO Content at Various Oxygen Partial Pressures

Wang

Huang

Blanpain

et al. 2023

The Minerals, Metals &Amp; Materials Series

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Crystallization Behavior of Liquid CaO-SiO2-FeO-MnO Slag in Relation to Its Reaction with Moisture

Abstract: Please refer to published version for the most recent bibliographic citation information. If a published version is known of, the repository item page linked to above, will contain details on accessing it.

Cited by 10 publications

References 51 publications

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

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

Effect of Surface Oxides on the Melting and Solidification of 316L Stainless Steel Powder for Additive Manufacturing

Melting and Solidification Behaviors of the Copper Slags with Different CaO Content at Various Oxygen Partial Pressures

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