Dissolution Behavior of Lime into Steelmaking Slag

Kitamura, Shin Ya

doi:10.2355/isijinternational.isijint-2017-109

Cited by 33 publications

(24 citation statements)

References 25 publications

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“…Eccentrically stirring the molten slag (containing a lime cube); [9,10] stirring slag using a Mo impeller [11] or alumina impeller; [12] argon gas bubbling in slag via an iron tube [13,14] Increased mass transfer in slag due to forced convection; realistic method(s) to simulate the actual situation in BOS converters.…”

Section: Forced Convectionmentioning

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: Forced Convectionmentioning

confidence: 99%

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

Spooner

et al. 2021

steel research int.

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“…In real industrial practices, the "slag" very often consists of not only liquid phase but also some other phases. It is well known that in the BOF process, the slag usually contains different solid phases, such as undissolved lime particles [80][81][82] and precipitated solids, e.g., calcium silicate. [80,83] When slag foaming takes place in BOF, the slag consists of also gas phase and even iron droplets.…”

Section: Apparent Viscositymentioning

confidence: 99%

The Laboratory Study of Metallurgical Slags and the Reality

Sichen

Huss

Vickerfält

et al. 2021

steel research int.

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The development of new materials and their production processes along with the environmental constraints demand new data of high quality, especially thermodynamic and physical property data. As slags play a crucial role in metallurgical processes and recycling, the need of better understanding of the reaction mechanisms between slag and metal is also increasingly felt. High precision data and better understanding of the reaction mechanism require efficient collaboration between the researchers in the laboratory and in the industries. Unfortunately, in some cases, the reported data are not obtained in well-controlled experimental conditions. Without the knowledge of the experimental conditions, the use of the data in industrial practice would possibly lead to unintended results. In other cases, the measurements themselves, even their principles, are questionable. This review article addresses how to make the laboratory investigation more relevant to the industrial reality. Some existing uncertainties in the laboratory studies are also discussed. To help a sensible discussion, some specially designed experiments are conducted to support the argument. The review is focused on slag properties (namely, sulfide capacity, phosphate capacity, apparent viscosity, and apparent interfacial tension) and studies of interfacial slag phenomena.

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“…In this study, it increased with the gas flowrate, but was not strongly influenced by the density of lime, when the C 2 S layer formed and covered the lime surface. It is considered to be the most realistic method to simulate the actual situation in steelmaking process (Kitamura, 2017).…”

Section: Lime Dissolution and Formation Of Phosphorus-rich Solid Solumentioning

confidence: 99%

A Review of Multi-phase Slag Refining for Dephosphorization in the Steelmaking Process

et al. 2020

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Dephosphorization has always been a challenging task in the steelmaking process. In the traditional studies, CaO-based steelmaking slag was usually treated as a homogeneous liquid phase to analyze the dephosphorization equilibrium between molten slag and hot metal (slag/metal). In fact, the slag shows a coexisting state of both liquid and solid at steelmaking temperature. In recent years, multi-phase slag refining has been proposed and proved to be an efficient technique to improve the utilization of solid lime and the dephosphorization efficiency in steelmaking practices. The present review focuses on hot issues for the multi-phase slag refining, including the dissolution of solid lime to the molten slag, the formation of 2CaO·SiO2 and phosphorus-rich solid solution of 2CaO·SiO2-3CaO·P2O5, as well as the phosphorus distribution ratio between the solid and liquid phases in the multi-phase slag. In addition to the discussion on thermal and kinetic factors of dephosphorization, the necessity of further research is proposed on the dissolution behavior of phosphorus-rich solid solution and phosphorus redistribution in the slag of high temperature, high basicity and high FeO in the final stage of converter steelmaking. Then, a more applicable dynamic model of dephosphorization could be expected considering the equilibrium not only between molten slag and liquid metal but also among the phases of the multi-phase slag in steelmaking process. Furthermore, the modelling work is beneficial for the fine control of the BOF process and the development of intelligent manufacturing in steelmaking industry.

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Dissolution Behavior of Lime into Steelmaking Slag

Cited by 33 publications

References 25 publications

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

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

The Laboratory Study of Metallurgical Slags and the Reality

A Review of Multi-phase Slag Refining for Dephosphorization in the Steelmaking Process

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