Kinetics and mechanism of smelting reduction of fluxed chromite Part 2 Chromite–flux pellets in Fe–C–Si melts

Zhang

et al. 2023

Metals

Against the background of low global carbonization, blast furnace ironmaking technology with coking puts huge amounts of pressure on the global steel industry to save energy and reduce emissions due to its high pollution levels and high energy consumption. Bath smelting reduction technology is globally favored and studied by metallurgists as a non-blast furnace ironmaking technology that directly reduces iron ore into liquid metal without using coke as the raw material. The smelting reduction reaction of iron ore, which is the core reaction of the process, is greatly significant to its productivity and energy saving. Therefore, this paper focuses on the behavior and mechanism of iron ore’s smelting reduction. This work focuses on three key aspects of smelting reduction, namely, the thermal decomposition characteristics of iron ore during the smelting reduction, the smelting reduction mechanism of iron-ore particles, and the smelting reduction mechanism of FeO-bearing slag. The experimental study methods, reaction mechanisms, influencing factors, and kinetic behavior of the three are highlighted. In this work, the reaction mechanism of thermal iron-ore decomposition, iron-ore particle smelting reduction, and FeO-bearing slag smelting reduction on the three reactions were observed, providing a theoretical basis for how to select and optimize raw materials for the bath smelting reduction process. Moreover, the kinetic study clarifies the limiting steps of the reactions and provides guidance for an improvement in the reaction rate. However, certain blank points in previous studies need to be further explored, such as the differences in the research results of same factor, the large variation in reaction activation energy, and the coupling mechanism and inter-relatedness of the three key aspects’ reactions with each other.

Section: ) Melt Compositionmentioning

confidence: 66%

Section: Research Progress Of Experimental Methodsmentioning

confidence: 99%

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Study on the Bath Smelting Reduction Reaction and Mechanism of Iron Ore: A Review

Zhang

et al. 2023

Metals

“…The studies in the past [7][8][9][10] indicated that the interfacial reaction process between slag and metal may be controlled by the mass transfer of Cr2O3 in slag, the chemical reaction at the interface and the diffuseness of Cr in the boundary layer of metal side respectively, or by them together. (2) where, is the mole number of Cr2O3 in slag, mol, t is the time, s, F is the interfacial area between slag and metal, m 2 , kS is the mass transfer coefficient of Cr2O3 in slag, m·s…”

Section: Elementary Steps and Rate Controlling Link Ofmentioning

confidence: 99%

Mathematical Modeling of Refining of Stainless Steel in Smelting Reduction Converter Using Chromium Ore

et al. 2012

For predicting and controlling the process of chromium ore smelting reduction in a converter preferably, the coupling dynamic model is established for the first time based on the kinetic models of chromium ore dissolution and interfacial reducing reaction between the slag and the metal. It can decrease the refining time considerably and improve the production efficiency for producing 12 wt% Cr stainless steel crude melts in a converter when the initial hot metal contains the definite chrome metal at 1 560°C. Under the conditions of the mathematical model, the effect of chromium ore size on the process of producing stainless steel crude melts by chromium ore smelting reduction in a converter is great when the particle size of chromium ore increases to a certain value. In such condition, the dissolution of chromium ore in the slag is the rate controlling step at a certain stage of refining and the rate of chromium ore smelting reduction is controlled jointly by the dissolution and the reduction of chromium ore. The effect of temperature on the process of chromium ore smelting reduction in a converter is significant. The mean reduction rate of chromium ore increases from 0.052 wt%·min -1 to 0.175 wt%·min -1 with the increasing of temperature from 1 540°C to 1 580°C.

“…The smelting reduction of chromite ore is among the most noteworthy technological advancements for the direct alloying of chromium. [3][4][5][6][7][8] The smelting reduction of chromite ore involves dissolving chromite in a suitable slag system and reducing the dissolved chromium oxide using a reduction agent that is dissolved in the metal melt. Despite Yokoyama's belief that the reduction reaction occurring at the interface between slag and metal melt was the pivotal stage for chromium recovery, [9] numerous studies have suggested that the dissolution of chromite ore in the slag melt is in fact the critical step for achieving chromium recovery through the smelting reduction of chromite ore. [10][11][12][13] Hence, research aimed at investigating the dissolution of chromite in slag is of utmost importance in facilitating the process of chromium recovery.…”

Section: Introductionmentioning

confidence: 99%

Dissolution Behavior of Chromite Ore in CaO‐SiO₂ System

Xiao

Wei

et al. 2023

steel research int.

Numerous investigations proposed that the dissolution of chromite ore is the rate‐controlling step for the smelting reduction of chromite ore. The mechanism of chromite ore dissolution in the binary CaO‐SiO2 system is presented. The effect of basicity, temperature, and reducing conditions on chromite ore dissolution is elaborated. The solubility of chromite ore increases considerably when the basicity increases from 0.56 to 0.65. However, the solubility of chromite ore decreases when the basicity further increases from 0.65 to 0.74. The positive effect of reducing conditions on the solubility of chromite ore is evident. The maximum dissolved Cr2O3 in slag under reducing conditions by using a graphite crucible reaches 2.6 wt% after 15 min of dissolution. The element diffusion behavior at the chromite/slag interface is elaborated through SEM‐EDS technology. The analysis suggests that the rate‐controlling step in the early stage is the interface dissolution reaction. After a certain time, the rate‐controlling step becomes the mass transfer of Cr2O3 from the chromite ore to the chromite/slag interface. The activation energy of the dissolution reaction is = 285.29 kJ mol−1.