Effects of pre-oxidation on the hydrogen-rich reduction of Panzhihua ilmenite concentrate powder: Reduction kinetics and mechanism

The iron and steel industry is a major CO2 emitter and an important subject for the implementation of carbon emission reduction goals and tasks. Due to the complex ore composition and low iron grade, vanadium–bearing titanomagnetite smelting in a blast furnace consumes more coke and emits more carbon than in an ordinary blast furnace. Injecting hydrogen–rich gas into blast furnace can not only partially replace coke, but also reduce the carbon emission. Based on the whole furnace and zonal energy and mass balance of blast furnace, the operation window of the blast furnace smelting vanadium–bearing titanomagnetite is established in this study on the premise that the thermal state of the blast furnace is basically unchanged (raceway adiabatic flame temperature and top gas temperature). The effects of different injection amounts of hydrogen–rich gases (shale gas, coke oven gas, and hydrogen) on raceway adiabatic flame temperature and top gas temperature, and the influence of blast temperature and preheating temperature of hydrogen–rich gases on operation window are calculated and analyzed. This study provides a certain theoretical reference for the follow–up practice of hydrogen–rich smelting of vanadium–bearing titanomagnetite in blast furnace.

/pdf/use-of-hydrogen-rich-gas-in-blast-furnace-ironmaking-of-v-2rqpdc5g.pdf

Use of Hydrogen–Rich Gas in Blast Furnace Ironmaking of V–bearing Titanomagnetite: Mass and Energy Balance Calculations

Recent technology developments in beneficiation and enrichment of ilmenite: A review

Constructing n-type doped perovskite from Ti-bearing solid waste to boost the NO-to-NO2 oxidation

In COREX process, the top gas recycling (TGR) is an effective recovery and utilization technology for the high-quality gas by-produced from the melter gasifier, which can reduce its fuel consumption and emis-sions, and is of great significance to low carbon ironmaking. However, low concentration N 2 is contained in the top gas, it is unfavorable to the smelting of V–Ti bearing burden because the high temperature solid solution Ti(C, N) is formed in the semi-coke bed and deteriorates the burden permeability of the melter gasifier. The effect of N 2 concentration (0–10 vol%) on the softening, melting and dropping behavior of V–Ti bearing burden is investigated under simulated COREX conditions. Results show that the increasing N 2 concentration will promote the formation of Ti(C, N), increase the slag viscosity and its wettability to coke, greatly increase the burden dropping temperature, which reduces the slag dropping rate from 68.2% to 18.8%. In addition, slag foaming is caused and the gas permeability of V–Ti bearing burden is deterio-rated. The vanadium contents of dropping iron and residual iron are decreased from 0.051 wt% and 0.166 wt% to 0.043 wt% and 0.161 wt%, when the N 2 concentration in reducing gas changes from 0 vol% to 10 vol%. If the pressure drop needs to be controlled below 20 kPa, the N 2 concentration in the reducing gas should not exceed 5 vol%, that is, the top gas injection volume should be less than 60%.

https://www.jstage.jst.go.jp/article/isijinternational/62/9/62_ISIJINT-2022-071/_pdf

Effect of Top Gas Recycling Technology on the Softening, Melting and Dropping Behavior of V–Ti Bearing Burden in COREX Process

Titanium carbides, oxides, nitrides, and carbonitrides possess many special and excellent properties. But the high production cost caused by the traditional carbothermic reduction process severely limits the wide applications. In this study, a novel synthesis process has been proposed by reducing and carbonitriding TiO2 with a CH4-H2-N2 gas mixture at low temperatures. The synthesis of Ti(C, N, O), reaction mechanism, and the composition of the product have been investigated. Thermodynamic analysis indicated that TiO2 could be ultimately reduced and carbonitrided to Ti(C, N, O) by CH4-H2-N2 gas mixture. Based on the predictions of thermodynamics, the effects of reduction time, temperature, and gas composition have been studied experimentally. The obtained results indicated that increasing reduction temperature and introduction of N2 are beneficial to the synthesis of Ti(C, N, O). Finally, the optimum reaction conditions have been obtained. The density functional theory (DFT) results further demonstrated the reaction mechanism. This work provides a new approach to prepare metallic carbonitrides from their oxides.

Synthesis of Ti(C, N, O) ceramic from rutile at low temperature by CH4-H2-N2 gas mixture

In the high-speed wheel steel, the composite inclusions of MnS–Al_2O_3 reduce the overall elastic modulus of the Al_2O_3 and avoid the fatigue crack around the inclusions. It is of great industrial significance to clarify the mechanism of formation progress of the composite inclusions. In this paper, the formation process of the composite inclusions is simulated on an atomic scale by the first principle calculations through the adsorption model. The structure of MnS–Al_2O_3 composite inclusion was optimized through a series of cases with different adsorption sequences of the Mn and S atoms on the surface of Al_2O_3 inclusions. The most stable adsorption positions of the Mn and S atoms are determined by comparing the adsorption energy through structural optimization. The adsorption of the atoms is further explained by the calculation results of the density of state (DOS), the partial density of state (PDOS), and charge density distribution (CDD).

Investigation on the Formation Pathway of the MnS–Al_2O_3 Inclusions at Atomic Level in High-Speed Wheel Steel

The utilization of titanium-containing blast furnace slag has been an unsolved problem for a long time. Failure to make effective use of the slag, which is caused by a high TiO2 content within it, not only results in a waste of resources, especially titanium, but also increases environmental risk. The key to address the problem is the enrichment and extraction of TiO2 from the slag first. Therefore, in order to study the enrichment of titanium, the crystallization behavior of TiO2-CaO-SiO2-Al2O3-MgO pentabasic slag, the main compositions of titanium-containing blast furnace slag, within the basicity range of 1.1–1.4 was investigated theoretically and experimentally. Thermodynamic calculation shows that perovskite is the main titanium-containing phase and titanium can be enriched in perovskite. By decreasing the temperature, perovskite precipitates at first. Additionally, with the increase of basicity, perovskite precipitation temperature increases continuously, and its amount of precipitation almost does not change, while the amounts of other phases change obviously. The experimental results demonstrate similar results except for the amount of perovskite (with the increase of basicity, perovskite precipitation amount increases slightly), caused by kinetic reason. In addition, the morphology of the slag at different scales was observed. The surface of the cooled slag is granular, vein-like, and irregular, multilaterally shaped from outside to inside. The crystal is dendritic with a spine-like trunk, and the edge is blade-like. In terms of the structure of the crystal, the inner part of it is perovskite, and the outer part is covered with a layer of other phases with spinel inlaying it. Finally, the precipitated mechanism is proposed as well.

https://www.mdpi.com/2073-4352/11/6/583/pdf

The Crystallization Behavior of TiO2-CaO-SiO2-Al2O3-MgO Pentabasic Slag with a Basicity of 1.1–1.4


 Titanium carbides, oxides, nitrides and carbonitrides possess many special and excellent properties. But the high production cost caused by the traditional carbothermic reduction process severely limits the wide applications. In this study, a novel synthesis process has been proposed by reducing and carbonitriding TiO2 with CH4-H2-N2 gas mixture at low temperatures. The synthesis of Ti(C, N, O), reaction mechanism and the products composition have been investigated. Thermodynamic analysis indicated that TiO2 could be ultimately reduced and carbonitrided to Ti(C, N, O) by CH4-H2-N2 gas mixture. Based on the predictions of thermodynamics, the effects of reduction time, temperature, and gas composition have been studied experimentally. The obtained results indicated that increasing reduction temperature and introduction of N2 are beneficial to the synthesis of Ti(C, N, O). Finally, the optimum reaction conditions have been obtained. The density functional theory (DFT) results further demonstrated the reaction mechanism. This work provides a new approach to prepare metallic carbonitrides from their oxides.

/pdf/synthesis-of-ti-c-n-o-from-tio2-by-ch4-h2-n2-gas-mixture-at-4wjiguk8qv.pdf

Synthesis of Ti(C, N, O) from TiO2 by CH4-H2-N2 Gas Mixture at Low Temperature

Enhancement of Electrochromic Performance of NiO by Introducing MXene via In Situ Electrodeposition

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