A Kinetic Study Investigating the Carbothermic Recovery of Chromium from a Stainless-Steel Slag

Leuchtenmüller, Manuel; Antrekowitsch, Jürgen; Steinlechner, Stefan

doi:10.1007/s11663-019-01649-2

Cited by 15 publications

(7 citation statements)

References 8 publications

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“…The applied mathematical model describing the reaction kinetics of a system of reduction reactions is based on a more simple approach described by Leuchtenmueller et al on the carbothermic chromium oxide reduction. [50] In this study, obtained data of six individual high-temperature reduction experiments were in good agreement (min. R 2 = 0.94) with the developed kinetic model.…”

Section: Discussionsupporting

confidence: 75%

Carbothermic Reduction of Zinc Containing Industrial Wastes: A Kinetic Model

Leuchtenmueller

Legerer

Brandner

et al. 2021

Metall Mater Trans B

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Effective recycling of zinc-containing industrial wastes, most importantly electric arc furnace dust, is of tremendous importance for the circular economy of the steel and zinc industry. Herein, we propose a comprehensive kinetic model of the combined carbothermic and metallothermic reduction of zinc oxide in a metal bath process. Pyro-metallurgical, large-scale lab experiments of a carbon-saturated iron melt as reduction agent for a molten zinc oxide slag were performed to determine reaction constants and accurately predict mass transfer coefficients of the proposed kinetic model. An experimentally determined kinetic model demonstrates that various reactions run simultaneously during the reduction of zinc oxide and iron oxide. For the investigated slag composition, the temperature-dependent contribution of the metallothermic zinc oxide reduction was between 25 and 50 pct of the overall reaction mechanism. The mass transfer coefficient of the zinc oxide reduction quadrupled from 1400 °C to 1500 °C. The zinc recovery rate was > 99.9 pct in all experiments.

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Section: Discussionsupporting

confidence: 75%

Carbothermic Reduction of Zinc Containing Industrial Wastes: A Kinetic Model

Leuchtenmueller

Legerer

Brandner

et al. 2021

Metall Mater Trans B

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“…Note the trivalent Cr (III) in the form of oxide is less toxic but it can be oxidized to harmful Cr (VI) at high oxygen concentrations or high MnO oxides. In general, the methods for recovering valuable metals/metal oxides from the BOS slags are categorized into physical separation, [121][122][123][124][125][126][127][128][129] reduction process, [130][131][132][133][134][135][136] and oxidation process. [137][138][139]…”

Section: Materials Recyclingmentioning

confidence: 99%

“…The highest reduction ratio of Fe and Cr achieved was 93.92% and 72.76%, respectively, under the condition of carbon equivalent 2, reduction temperature 1600 ºC, and binary basicity 1.2. [133][134][135] Adamczyk et al [136] compared the efficiency of the reducing agents of C, Al, FeSi, and SiC for reduction of chromium in the SSS slag. Al was the strongest reducing agent; however, it leads to reducing a lot of SiO 2 because of the strong reactivity of aluminum.…”

Section: Reduction Processmentioning

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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“…Metals recovery from slags can be done via physical and chemical means. Physical separation is applicable for large metallic particles; the slag should be first properly comminuted to liberate the metals after which metal is removed by gravimetric and/or magnetic methods [13][14][15][16]. EAF slags have the best potential in good metal recovery due to the highest metal content.…”

Section: Metals Separation and Recovery: Pyroand Hydrometallurgical Treatmentsmentioning

confidence: 99%

“…It might be a separate "reduction furnace" in which valuable metals could be reduced from the slag to very low contents in a properly stirred reactor under highly reducing conditions, e.g., in the presence of a Fe-C or Fe-C-Cr melt. Also, other reductants like Si and Al are possible [15][16][17][18][19][20][21]. Cr bound is most difficult to reduce in spinels like MgCr 2 O 4 .…”

Section: Metals Separation and Recovery: Pyroand Hydrometallurgical Treatmentsmentioning

confidence: 99%

A Review of Circular Economy Prospects for Stainless Steelmaking Slags

Holappa

Kekkonen

Jokilaakso

et al. 2021

J. Sustain. Metall.

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The world of stainless steel production was 52 Mt in 2019, and the annual amount of slags including electric furnace, AOD converter, ladle, and casting tundish, was estimated at 15–17 Mt. Nowadays, only a minor fraction of slags from stainless steel production is utilized and a major part goes to landfilling. These slags contain high-value elements (Cr, Ni, Mo, Ti, V…) as oxides or in metallic form, some of them being environmentally problematic if dumped. Thus, any approach toward circular economy solutions for stainless steel slags would have great economic and environmental impacts. This contribution examines the slags from different process stages, and the available and new potential means to increase internal recycling and to modify slags composition and structure by optimizing their properties for reclaiming in high-value applications. Eventual methods are, e.g., fast controlled cooling and modifying additives. Means to recover valuable metals are discussed as well as potential product applications to utilize various slags with different chemical, physical, and mechanical properties. By integrating the treatments and steering of slags′ properties to the total process optimization system, the principles of circular economy could be achieved. Graphical Abstract

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A Kinetic Study Investigating the Carbothermic Recovery of Chromium from a Stainless-Steel Slag

Cited by 15 publications

References 8 publications

Carbothermic Reduction of Zinc Containing Industrial Wastes: A Kinetic Model

Carbothermic Reduction of Zinc Containing Industrial Wastes: A Kinetic Model

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

A Review of Circular Economy Prospects for Stainless Steelmaking Slags

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