Machine learning-based prediction of a BOS reactor performance from operating parameters

A machine learning-based analysis was applied to process data obtained from a Basic Oxygen Steelmaking (BOS) pilot plant. The first purpose was to identify correlations between operating parameters and reactor performance, defined as rate of decarburization (dc/dt). Correlation analysis showed, as expected a strong positive correlation between the rate of decarburization (dc/dt) and total oxygen flow. On the other hand, the decarburization rate exhibited a negative correlation with lance height. Less obviously, the decarburization rate, also showed a positive correlation with temperature of the waste gas and CO2 content in the waste gas. The second purpose was to train the pilot-plant dataset and develop a neural network based regression to predict the decarburization rate. This was used to predict the decarburization rate in a BOS furnace in an actual manufacturing plant based on lance height and total oxygen flow. The performance was satisfactory with a coefficient of determination of 0.98, confirming that the trained model can adequately predict the variation in the decarburization rate (dc/dt) within BOS reactors. View Full-Tex

Direct observation via in situ heated stage EBSD analysis of recrystallization of phosphorous deoxidised copper in unstrained and strained conditions

Recrystallization of phosphorous deoxidised copper used for strength critical applications at elevated temperatures was investigated by means of in situ heated stage EBSD analysis using a Gatan Murano heated stage mounted within a Carl Zeiss Sigma FEGSEM electron microscope. The influence of applied strain as the result of deformation within a Nakajima test as an analogue for industrial forming on the recrystallization temperature was investigated, the impact of increased heating rates on microstructural evolution was also investigated. Inverse pole figure plots combined with regions of reduction in local misorientations and variations in geometrically necessary dislocations were used to establish the point of recrystallization and the recrystallized fraction of the material. Recrystallization was observed to occur at temperatures as low as 130 °C in highly strained samples compared to around 300 °C within the annealed samples dependent upon heating rate. Increased heating rates were observed to produce a finer final grain structure but had little effect on presence of 60° grain twins, which was influenced more by initial material condition

Challenges and opportunities for steel scrap utilisation in the UK

UK generates around 11.0 Mt steel scrap per year with 80% being exported, while only 22% of UK crude steel (~7.3 Mtpa) is produced by scrap-based EAF route. Increasing the scrap utilisation in the UK steel industry could be an enabler for realising a circular steel economy and achieving net zero emissions. This talk will first identify the challenges for increasing the scrap utilisation in the UK such as steel recycling capacity, scrap quality, and technical barriers, and then explore the opportunities including UK steel demand, carbon emission taxation, circular supply chain, and technology development for increasing scrap utilisation

Spontaneous emulsification as a function of material exchange.

Direct visualization at 1873 K of 0% to 8% molten FeAl droplets suspended in a SiO2 enriched oxide medium was carried out to image the evolution of droplet morphology during reaction between Al and SiO2. Phenomena such as perturbation growth, necking and budding of offspring droplets from a bulk body are observed. The observations are used to discuss and inform a new approach to the nature of interfacial tension and the impact this has on concepts used to define interfacial tension for a two phase system with material exchange across the interface. The mapping of global interfacial tension coupled with free energy dissipation has been used to give an energetic reasoning as to the behaviour seen with respect to aluminium content in the metal phase

Hidden phenomena during transient reaction trajectories in liquid metals processing

The transient trajectory taken for a system striving toward equilibration has consequences on the rate of processes and on the chemical and physical state of products in metallurgical processes. A case study approach to recent advancements in liquid steel processing is given. A combination of techniques and knowledge developed is given as a targeted showcase of the authors’ contributions to the understanding of liquid metal droplet reactions and their contribution to the large-scale production processes within the steel industry. Examples relevant to novel ironmaking technologies, oxygen steelmaking, ladle metallurgy, and continuous casting are discussed, showing the range of processes that benefit from greater understanding in this area. This article considers specifically the reaction of liquid ferrous droplets, immersed in molten oxides, involving key alloying components, including phosphorus, aluminum, and carbon. The studies use high-temperature–confocal scanning laser microscopy (HT-CSLM), X-ray computed tomography (XCT), phase-field modeling, and in situ limited angle X-ray imaging. These techniques have seen significant development over recent years, and the combination of these powerful tools reveals the occurrence of spontaneous emulsification driven by chemical reaction (in the case of oxygen/phosphorus/aluminum reactions) and gas-phase formation (in the case of decarburization) both internally and externally to a steel droplet. A key finding is that the interfacial area pertinent for the heterogenous reactions to occur changes considerably (by up to an order of magnitude) depending on the chemical driving force. Additional key findings include the shift between preferential internal and external gas nucleation during decarburization, an inflection point of behavior as to whether or not spontaneous emulsification will occur (within the study discussed, this is between 3 and 4 wt pct Al) and the pathway of perturbation growth through which spontaneous emulsification occurs, including the physical maxima a perturbation will grow to before breaking away from the parent droplet

Multi-mode control based on HSIC for double pendulum robot

Double pendulum robot has four equilibrium points: Down-Down, Down-Up, Up-Down, and Up-Up. Define the transfer control from one equilibrium point to another equilibrium point as acrobatic action of DPR, and there are total of 20 acrobatic actions. This paper proposes the multi-mode control algorithm based on Human Simulated Intelligent Control theory for the realization process of those acrobatic actions, which has the structure of multi sub-controllers and multi control modes. As an example, the acrobatic action from Down-Up to Up-Down is realized in simulation and real-time experiments, and the results demonstrate the effectiveness of the proposed algorithm

Fundamental understanding on the use of different carbon sources in the alternative ironmaking HIsarna process

HIsarna process offers a low CO2 emission alternative to the blast furnace for hot metal production. This new smelting ironmaking technology is flexible in raw materials such as substitution of coal with biomass. The reduction process is conducted through multiple mechanisms within the smelting reduction vessel (SRV) including reactions of the gaseous products from thermal decomposition of carbonaceous materials with iron oxide in slags. Since the construction of the HIsarna pilot plant (at the capacity of 8t hot metal/hour) in Tata Steel site in the Netherlands in 2010, several successful trial campaigns have been completed using thermal coals. Campaigns to partially replace coal with biomass and charge steel scraps in the SRV were also successfully conducted since 2018 demonstrating further significant CO2 emission reduction, however, the change in process performance due to biomass injection was noticed. To advance the fundamental understanding of the use of different carbonaceous materials in the HIsarna process and help optimise the carbonaceous material selection, a systematic research has been carried out for different carbon sources under simulated HIsarna thermal conditions. The thermodynamic and kinetic behaviours of the carbon-gas-slag-metal systems have been studied for coal and biomass injection in laboratory experiments. This talk will introduce some research findings from this systematic research, including slow/rapid devolatilisation of the carbon sources injected, structural characteristics of the resultant chars, and slag-carbon reactions for coals and biomass

Can there be a sunrise in steel town?

A sustainable UK steel industry is vitally important to UK’s future growth prospects. This article first analyses the grand trends and challenges that the UK steel industry is facing. Then alternative iron making processes are briefly reviewed with regard to its flexibility in raw material and energy and its reduction in CO2 emissions. It is concluded that in the long-term, the scrap-based EAF route can be considered as a viable process route for the UK steel industry. For the current integrated process, its sustainability can be achieved by substantially improving its energy/material efficiency and by focusing on the creation of value-added steel products. It also points out that ensuring the sustainability of the UK steel industry requires a clear strategy, substantial capital expenses and support from the government and the industry itself. The UK has to invest in/re-shape steel-related research creating new competences for the viability of the industry

Quasi in-situ analysis of geometrically necessary dislocation density in α-fibre and γ-fibre during static recrystallization in cold-rolled low-carbon Ti-V bearing microalloyed steel

In the present study, cold-rolled low-carbon steel is annealed at three different conditions: 700 oC for 0 s, 800 oC for 0 s and 800 oC for 2 min at the heating rate of ~10 oC/s. Recrystallization behaviour on sample surface is studied using a heated stage Scanning Electron Microscopy and Electron Backscattered Diffraction. For the lower annealing temperature of 700 oC with no dwell, almost no recrystallization is observed and microstructure resembles the as-received deformed material with the exception of occasional sub-micron sized nuclei. For the annealing conditions of 800 oC 0 s and 800 oC 2 min, onset and evolution of recrystallization is observed in-situ as a function of the initial as-cold rolled texture. Slower recovery rate of alpha fibre than gamma fibre is observed and confirmed by lower drop in average geometrically necessary dislocation (GND) density for un-recrystallized alpha fibres (1.1E+14 m-2 for 700 oC 0 s , 1.4E+14 m-2 for 800 oC 0 s and 4.5E+14 m-2 for 800 oC 2 min) than for un-recrystallized gamma fibre grains (3.0E+14 m-2 for 700 oC 0 s , 6.2E+14 m-2 for 800 oC 0 s and 9.8E+14 m-2 for 800 oC 2 min) during annealing. Strong gamma texture in recrystallized matrix is found for annealing conditions of 800 oC 0 s and 800 oC 2 min. From TEM characterisation it was shown that sub-grain boundaries are decorated with fine precipitates (diameter d < 15 nm) of titanium-vanadium carbides (Ti,V)C for the annealing condition of 700 oC 0 s, which suggests that these precipitates play a major overall role in retardation of the recrystallization kinetics

Effects of slag composition on H2 generation and magnetic precipitation from molten steelmaking slag-steel reaction

In this paper, the effects of slag composition (slag basicity CaO/SiO2 and FeO concentration) on the amounts of H2 gas generated and the magnetic spinel phase precipitated as a result of the reaction between synthetic steelmaking slag and steam at 1873 K (1600 °C) were studied by thermodynamic simulation (using Thermodynamic Package FactSage 7.0) and laboratory experiments. The thermodynamic calculation showed that, upon increasing slag basicity (CaO/SiO2) from 1.0 to 2.5, for the reaction of 100 g of slags with 100 g of H2O gas, the accumulated amount of the produced H2 gas increased from 0.17 to 0.27 g, while the amount of magnetic spinel phase first increased and then decreased, with the maximum precipitation of 16.71 g at the basicity of 1.5. When the FeO concentration increased from 15 to 30 pct for the slag with basicity of 2.0, the accumulated amount of the produced H2 gas increased from 0.17 to 0.28 g, and the amount of magnetic spinel phase increased from 5.88 to 10.59 g. The laboratory experiments were conducted in confocal laser scanning microscope to verify the reaction between 0.2 g of slag and 3.75 L of H2O-Ar gas (PH2O=0.2atm). The results indicated that, for 100 g of slags, upon increasing slag basicity (CaO/SiO2) from 1.0 to 2.5, both the produced H2 gas and magnetic spinel phase first increased and then decreased, with the maximum amounts being 0.09 g of gas and 37.00 g of magnetic spinel phase at the slag basicity of 1.50. For the FeO concentration increasing from 15 to 30 pct, the amounts of both the produced H2 gas and magnetic spinel phase increased from 0.04 to 0.10 g and from 18.00 to 27.00 g, respectively. The reaction rate between the molten CaO-SiO2-FeO-MnO-Al2O3-MgO slag and the moisture (PH2O=0.2atm) increased with the increasing FeO activity in the slag. The dependence of the reaction rate (mol/cm2/s) on FeO content can be expressed as r=(7.67(aFeO)−2.99)×10−7