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ABSTRACTA novel horizontal stirring has been introduced to investigate the effect of such a stirring on the ladle profile during the combined stirring process at the refining stage. The multiphaseInterFoam solver has been updated to consider the induction forces imposed on the liquid bath by the magnetic stirrer.During the combined stirring stage, the gas plume is affected by the rotational movement. The gas plume seems to be intact in the lower one-third of the domain, then breaks into clusters in the upper section while the rotational movement of clusters dissipates a large portion of upward momentum of the bubbles. This prevents large openings in the slag layer and respectively, prevents the exposure of steel. It also disperses the bubbles to various sections of the ladle. Hence, such a novel stirring strategy seems to have the potential of improving the cleanness of the liquid steel during the ladle refining process.

A novel horizontal stirring has been introduced to investigate the effect of such a stirring on the ladle profile during the combined stirring process at the refining stage. The multiphaseInterFoam solver has been updated to consider the induction forces imposed on the liquid bath by the magnetic stirrer.During the combined stirring stage, the gas plume is affected by the rotational movement. The gas plume seems to be intact in the lower one-third of the domain, then breaks into clusters in the upper section while the rotational movement of clusters dissipates a large portion of upward momentum of the bubbles. This prevents large openings in the slag layer and respectively, prevents the exposure of steel. It also disperses the bubbles to various sections of the ladle. Hence, such a novel stirring strategy seems to have the potential of improving the cleanness of the liquid steel during the ladle refining process.

Lab-scale alloying experiments were carried out by first adding commercial low-carbon ferrochrome (LCFeCr) alloys and then adding ferroniobium (FeNb) alloys in 316-grade austenitic stainless steel in this study. The inclusion and precipitation characteristics in LCFeCr and FeNb were evaluated as well as in a 316 austenitic stainless steel after the alloy additions by using two- and three-dimensional characterization methods in combination with thermodynamic calculations. The results showed that MnCr2O4spinels and pure Al2O3were the main types of inclusions in LCFeCr alloys, while pure TiOx, Al2O3inclusions and complex TiOx-Al2O3aggregates were mainly found in FeNb alloys. After the addition of LCFeCr alloy to the steel, the SiO2contents in liquid inclusions decreased to some extent, while more inclusions containing higher MnO contents were observed. Some MnCr2O4spinel inclusions can be reduced by Si in steel and form liquid inclusions. Some MnCr2O4spinel and Al2O3inclusions from LCFeCr alloy can remain in the steel melt, which decreased the steel cleanliness. After the addition of FeNb alloy, pure TiOxinclusions present in this alloy can hardly be found in the steel melt. The inclusion types in steel were not changed so much but high Nb-containing phases were found around the inclusions and coarse Laves phases were formed in the matrix. Overall, this work aims to understand the impurity particle behavior during the alloying process when using ferroalloys to produce high-performance stainless steels.

ABSTRACTIn this work, a time-dependent thermodynamic AOD process model, TimeAOD3™, is proposed to be used as a prediction model at practice to reach the desired nitrogen level to lower the cost and carbon footprint. The model is developed from an existing model and integrated with Thermo-Calc®. The modelling results suggest a fairly good prediction when compared with production-scale heats. The relative error of dissolved nitrogen content during and after decarburisation is −0.05 < RE < 1.36 and −0.23 < RE < 0.29, respectively. Besides, most modelled dissolved N% are higher than the measurement during decarburisation. This is probably owing to the formation of high turbulence flow and CO gas bubble which can flush the dissolved nitrogen out of the bath at practice. Moreover, dissolved C%, Cr% in bath and Cr2O3%, CaO%, MgO% in slag, as well as bath temperature are also compared and studied.

In this work, a time-dependent thermodynamic AOD process model, TimeAOD3™, is proposed to be used as a prediction model at practice to reach the desired nitrogen level to lower the cost and carbon footprint. The model is developed from an existing model and integrated with Thermo-Calc®. The modelling results suggest a fairly good prediction when compared with production-scale heats. The relative error of dissolved nitrogen content during and after decarburisation is -0.05 < RE < 1.36 and -0.23 < RE < 0.29, respectively. Besides, most modelled dissolved N% are higher than the measurement during decarburisation. This is probably owing to the formation of high turbulence flow and CO gas bubble which can flush the dissolved nitrogen out of the bath at practice. Moreover, dissolved C%, Cr% in bath and Cr2O3%, CaO%, MgO% in slag, as well as bath temperature are also compared and studied.

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ABSTRACTThe wear of industrial refractory materials was studied in contact with slag containing high amounts of FeO using the rotating finger technique. The thermodynamic equilibrium of the refractory slag systems was also determined in Thermo-calc®and FactSage™. The studied refractories were alumina spinel, zirconia, graphite, silicon carbide (SiC), magnesia-carbon (MgO-C), chromite (Cr2O3), and MgO-Spinel (MgO–Al2O3). The fingers were rotated in a FeOx(90wt%) – SiO2(5wt%) – CaO (5wt%) slag for 3 hours in a molybdenum crucible at 100 RPM at 1700K. The wear of the refractory fingers was determined by dimensional changes and changes in composition of the slags. Only MgO-spinel refractories exhibited resistance to the slag. The thermodynamic equilibrium calculations were able to predict the experimental behavior when appropriate databases were used, with the exception of the chromite slag.

The wear of industrial refractory materials was studied in contact with slag containing high amounts of FeO using the rotating finger technique. The thermodynamic equilibrium of the refractory slag systems was also determined in Thermo-calc®and FactSage™. The studied refractories were alumina spinel, zirconia, graphite, silicon carbide (SiC), magnesia-carbon (MgO-C), chromite (Cr2O3), and MgO-Spinel (MgO–Al2O3). The fingers were rotated in a FeOx(90wt%) – SiO2(5wt%) – CaO (5wt%) slag for 3 hours in a molybdenum crucible at 100 RPM at 1700K. The wear of the refractory fingers was determined by dimensional changes and changes in composition of the slags. Only MgO-spinel refractories exhibited resistance to the slag. The thermodynamic equilibrium calculations were able to predict the experimental behavior when appropriate databases were used, with the exception of the chromite slag.

This research investigates a numerical simulation of swirling turbulent non-premixed combustion. The effects on the combustion characteristics are examined with three turbulence models: namely as the Reynolds stress model, spectral turbulence analysis and Re-Normalization Group. In addition, the P-1 and discrete ordinate (DO) models are used to simulate the radiative heat transfer in this model. The governing equations associated with the required boundary conditions are solved using the numerical model. The accuracy of this model is validated with the published experimental data and the comparison elucidates that there is a reasonable agreement between the obtained values from this model and the corresponding experimental quantities. Among different models proposed in this research, the Reynolds stress model with the Probability Density Function (PDF) approach is more accurate (nearly up to 50%) than other turbulent models for a swirling flow field. Regarding the effect of radiative heat transfer model, it is observed that the discrete ordinate model is more precise than the P-1 model in anticipating the experimental behavior. This model is able to simulate the subcritical nature of the isothermal flow as well as the size and shape of the internal recirculation induced by the swirl due to combustion.

Molybdenum is mainly used as an alloy material in the iron and steel industry and typically in the form of ferromolybdenum (FeMo). The current study aims to evaluate the energy consumption and greenhouse gas emissions (GHG) of four ferromolybdenum production cases using inventory inputs from a process model based on mass and energy conservations. The total energy required for producing 1 tonne of FeMo can vary between 29.1 GJ/t FeMo and 188.6 GJ/t FeMo. Furthermore, the corresponding GHG emissions differ from 3.16 tCO2-eq/t FeMo to 14.79 tCO2-eq/t FeMo. The main variances are from the mining and beneficiation stages. The differences in these stages come from the beneficiation degree (ore grade) and the mine type (i.e., co-product from copper mining). Furthermore, the mine type has a larger impact on the total energy consumption and GHG emissions than the beneficiation degree. More specifically, FeMo produced as co-product from copper mining has a lower environmental impact measured as the energy consumption and GHG emission among all the four cases. The inventory, consumed energy or associated GHG emission is independent on the initial ore grade and mine type in the downstream production stages such as roasting and smelting. Also, transport has the least impact on the energy consumption and GHG emission among all production stages.

The use of H-ZSM-5 and Al–MCM-41 in a two-stage system of mesoporous and microporous catalysts has been proved to improve the quality of bio-oil. Information about biomass pyrolysis kinetics is important to evaluate biomass as a feedstock for fuel or chemical production as well as efficient design and control of thermochemical processes. In this study, the catalytic pyrolysis kinetics of lignocellulose biomass with a mixed catalyst of H-ZSM-5 and Al–MCM-41 at different ratios is analyzed. The derived activation energies are determined using the Coats–Redfern model and an Avrami mechanism for first-order chemical reactions (A1, F1). Bench-scale experiments as well as quantifications of the resulted benzene, toluene, and xylene (BTX) yields have also been investigated. The thermogravimetric analysis–DTG results show that the presence of catalyst mixtures has significant effects on the fractions of volatile matter from lignocellulose biomass. Reactivity profiles have been obtained in the temperature range of 180 to 360 °C. The results show that the energy activation for lignocellulose biomass at a heating rate of 10 K min–1is 134.64 kJ mol–1and that the value decreases when using catalysts. However, when the heating rate is increased, the activation energy from the catalytic experiments is 6.3–66.0% higher than that from the biomass pyrolysis experiment. This is due to the production of coke. Overall, a H-ZSM-5/Al–MCM-41 ratio of 3:1 is found to be the best catalyst ratio in cracking hemicellulose and cellulose compared to other catalyst mixtures that were studied. The same catalyst ratio also attains the best interaction, in terms of a BTX product selectivity. The optimum activity of this catalyst mixture is reached at a temperature of 500 °C.

ABSTRACTA 1:4.6 scale physical model of a production argon oxygen decarburisation (AOD) converter was used to study the influence of top slag on the AOD process. Specifically, the gas penetration depth, fluid flow and slag behaviour under different nozzle diameters, nozzle numbers and gas flow rates were studied. The results show that the relative gas penetration depth generally increases linearly with an increased gas flow rate and a decreased nozzle size. Furthermore, the slag thickness increases linearly with an increased gas flow rate. In addition, the open-eye size was found to increase exponentially with an increased gas flow rate. Overall, three kinds of fluid flow patterns were found in the experiments: (i) a counter-clockwise rotation, (ii) a clockwise rotation and (iii) a double circulation with the plume in the middle of the converter. A counter-clockwise rotation was most common for the current experimental conditions.

A 1:4.6 scale physical model of a production argon oxygen decarburisation (AOD) converter was used to study the influence of top slag on the AOD process. Specifically, the gas penetration depth, fluid flow and slag behaviour under different nozzle diameters, nozzle numbers and gas flow rates were studied. The results show that the relative gas penetration depth generally increases linearly with an increased gas flow rate and a decreased nozzle size. Furthermore, the slag thickness increases linearly with an increased gas flow rate. In addition, the open-eye size was found to increase exponentially with an increased gas flow rate. Overall, three kinds of fluid flow patterns were found in the experiments: (i) a counter-clockwise rotation, (ii) a clockwise rotation and (iii) a double circulation with the plume in the middle of the converter. A counter-clockwise rotation was most common for the current experimental conditions.

Lamellar graphite iron (LGI) is an important technical alloy used to produce cast components for the automotive and the marine industry. The performance of the component is defined by the solidification sequence. Therefore, a lot of research work has been done in the field of solidification. The present work introduces a new measurement approach that combines advanced dilatation measurements with thermal analysis to investigate the solidification of LGI. The method involves a thermally balanced spherical sample. The temperature values are measured in the geometrical center and on the surface of the sample. The released heat of solidification is calculated by using the Fourier Thermal Analysis (FTA) method. The displacement values are measured on the surface of the sample. The volume change is calculated from the displacement data. The dilatation results clearly shows the advantage of the multidirectional measurement.

Biochar, originating from biomass pyrolysis, has been proven a promising catalyst for tar cracking/reforming with great coke resistance. This work aims to evaluate various engineered biochar-based catalysts on syngas production in a biomass pyrolysis and catalytic reforming process without feeding extra steam. The tested engineered biochar catalysts include physical- and chemical-activated, nitrogen-doped, and nickel-doped biochars. The results illustrated that the syngas yields were comparable when using biochar and activated biochar as catalysts. A relatively high specific surface area (SSA) and a hierarchical porous structure are beneficial for syngas and hydrogen production. A 2 h physical-activated biochar catalyst induced the syngas with the highest H2/CO ratio (1.5). The use of N-doped biochar decreased the syngas yield sharply due to the collapse of the pore structure but obtained syngas with the highest LHVgas(18.5MJ/Nm3). The use of Ni-doped biochar facilitated high syngas and hydrogen yields (78.2 wt % and 26 mmol H2/g-biomass) and improved gas energy conversion efficiency (73%). Its stability and durability test showed a slight decrease in performance after a three-time repetitive use. A future experiment with a longer time is suggested to determine when the catalyst will finally deactivate and how to reduce the catalyst deterioration.

Protonic conductors of BaZr0.5Ce0.3Ln0.2O3-δ (BZCLn532, Ln=Y, Sm, Gd, Dy) were successfully synthesized by using a cost-effective solid state reactive sintering (SSRS) method with 1 wt.% NiO was added as a sintering aid. The pellets of the BZCLn532 were obtained at sintering temperatures between 1300 - 1600 °C. The results show that the morphologies and the final relative densities of the obtained BZCLn532 pellets are influenced significantly when different sintering temperatures were applied. Densified pellets of the BZCLn532 can be prepared at sintering temperatures of 1600 °C (BaZr0.5Ce0.3Y0.2O3-δ) and 1400 °C (BaZr0.5Ce0.3Sm0.2O3-δ, BaZr0.5Ce0.3Gd0.2O3-δ and BaZr0.5Ce0.3Dy0.2O3-δ,). The conductivity results show that the BaZr0.5Ce0.3Y0.2O3-δ (BZCY532) and BaZr0.5Ce0.3Dy0.2O3-δ (BZCD532) ceramics are demonstrated to be good candidates of oxygen ion conductor and proton conductor materials for intermediate temperature solid oxide fuel cells (IT-SOFCs) applications.

Protonic conductors of BaZr0.5Ce0.3Ln0.2O3-δ (BZCLn532, Ln=Y, Sm, Gd, Dy) were successfully synthesized by using a cost-effective solid state reactive sintering (SSRS) method with 1 wt.% NiO was added as a sintering aid. The pellets of the BZCLn532 were obtained at sintering temperatures between 1300 - 1600 °C. The results show that the morphologies and the final relative densities of the obtained BZCLn532 pellets are influenced significantly when different sintering temperatures were applied. Densified pellets of the BZCLn532 can be prepared at sintering temperatures of 1600 °C (BaZr0.5Ce0.3Y0.2O3-δ) and 1400 °C (BaZr0.5Ce0.3Sm0.2O3-δ, BaZr0.5Ce0.3Gd0.2O3-δ and BaZr0.5Ce0.3Dy0.2O3-δ,). The conductivity results show that the BaZr0.5Ce0.3Y0.2O3-δ (BZCY532) and BaZr0.5Ce0.3Dy0.2O3-δ (BZCD532) ceramics are demonstrated to be good candidates of oxygen ion conductor and proton conductor materials for intermediate temperature solid oxide fuel cells (IT-SOFCs) applications.

One way to further utilise produced gases in an integrated metallurgical plant is to replace oil with gas as a reducing agent in a modern blast furnace. Accordingly, it is of great interest to study the injection of reducing gas into the blast furnace. Therefore, a three‐dimensional mathematical model has been developed which simulates the injection of the gas by lances into the tuyere. The model includes the coupled solution of the flow field and the chemical reaction of the gases in the tuyere. Two different types of fuel gas, coke oven gas (COG) and basic oxygen furnace gas (BOF) have been modelled using one injection lance. The modelling technique is presented and discussed as well as the implied results. Furthermore, process parameters such as different gas compositions etc. are investigated using the developed model. Not surprisingly, the main results show that the COG is combusted more completely than BOF gas, which leads to higher flame temperature of the blast putting demand forward to lower the heat load of the tuyere. However, the modelling of the raceway is as far not included in the model, hence the influence of the outlet boundary condition at the tuyere is not reflected in the presented results.

A fundamental mathematical model of the tuyere in a blast furnace has been developed earlier. In this study, the model is mainly used to predict the combustion reactions in the tuyere when coke oven gas is injected through lances located inside the tuyere. The combustion reaction is modelled using a simple reaction scheme with 3 possible reactions that can occur. The influence of the following parameters on the predicted velocities, temperatures and composition of the gas at the tuyere outlet is studied in this paper: (i) injection amount of coke oven gas, (ii) the use of 1 or 2 injection lances and (iii) the influence of the injection angles when using 2 injection lances. It is concluded that the maximum injecting amount using 1 and 2 lances is 10,000 nm3/h and 15,000 m3/h, respectively. The combustion conditions are better when using 2 injection lances are compared to 1 injection lance and the predicted results are not affected to a large degree when the injection angles are changed.

The spark‐induced modified optical emission spectroscopy (OES) technique developed by Ovako Steel makes it possible to rapidly determine inclusion characteristics in steel samples. In earlier investigations using the modified spark‐induced OES technique for steel samples taken from billets, predicted oxygen contents agreed well with results from conventional melt extraction analyses. In this investigation, samples taken during ladle treatment in an ASEA‐SKF ladle furnace were analysed using the modified OES technique. When comparing the results with inclusion characteristics determined by conventional analysis, similar trends were found. Plant trials were also carried out where three different top slag compositions were used. The purpose was to evaluate if the modified OES technique can be used to study the effect of changes in the refining operation on inclusion characteristics. Results indicated that the modified OES technique could be used to determine the effect of a changed slag composition on the inclusion characteristics in the steel. Since the modified OES method provides rapid feedback of inclusion characteristics, it has the potential of being used for faster optimisation of ladle refining operations.

This paper investigates the distribution of elements between slag and hot metal from a blast furnace through calculation of distribution coefficients from actual production data. First, samples of slag and hot metal tapped from a commercial blast furnace were taken continually at 10‐minute intervals for a production period of 68 hours. Distribution coefficients of manganese, silicon, sulphur and vanadium were then calculated from the results of the sample analyses. A major conclusion drawn from examination of the results was that the behaviour of the studied elements was as could be expected when approaching the equilibrium reactions from thermodynamic theory. The distributions of the elements in the slag‐metal system showed clear tendencies which did not appear to be influenced by the operational conditions of the furnace. For example, for manganese, vanadium and sulphur, it was found that a higher basicity led to a decreased distribution coefficient LMnand LV, but an increased LS, which is according to theory. Another observed relationship was that slag basicity increased with an increased carbon content in the hot metal, which indicated that SiO2was reduced to [Si] when the oxygen potential decreased. Furthermore, it was found that sulphur and silica behaviour likened that of acidic slag components, while the manganese oxide and vanadium oxide behaviour was similar to that of basic slag components.

A 2-dimensional fluid-flow model covering 3 phases (steel, slag and gas) has been augmented to include thermodynamic equations to study simultaneous reoxidation and desulphurization, including macro kinetic behaviour. The numerical simulations were isothermal. Predicted steel and slag component concentrations were compared with plant data from vacuum degassing and the agreement was found to be quite good. When the initial FeO content in the slag was increased, the predicted desulphurization rate decreased, the final sulphur content in the steel increased, and aluminium loss increased. When the temperature was increased, the predicted aluminium loss decreased somewhat. The effect of changes in temperature on the predicted final sulphur content was influenced by the initial FeO content in the top slag. The results show that the model can be used for future work on the dynamic modelling of slag/metal reactions if the initial FeO content is less than 3–4% (by weight).

In this paper, we present a numerical simulation of a laminar, steady and Newtonian flow of f-graphene nanoplatelet/water nanofluid in a new microchannel design with factors for increasing heat transfer such as presence of ribs, curves to enable satisfactory fluid mixing and changing fluid course at the inlet and exit sections. The results of this study show that Nusselt number is dependent on nanoparticles concentration, inlet geometry and Reynolds number. As the nanofluid concentration increases from 0 to 0.1% and Reynolds number from 50 to 1000, the Nusselt number enhances nearly up to 3% for increase in fluid concentration and averagely from 15.45 to 54.1 and from 14.5 to 55.9 for geometry with and without rectangular rib, respectively. The presence of ribs in the middle section of microchannel and curves close to hot walls causes a complete mixing of the fluid in different zones. When the nanoparticles concentration is increased, the pressure drop and velocity gradient will become higher. An increased concentration of nanoparticles in contribution with higher Reynolds numbers only increases the fraction factor slightly. (The fraction factor increases nearly 37% and 35% for Re= 50 and 1000, respectively.) The highest uniform temperature distribution can be found in the first zones of fluid in the microchannel and by further movement of fluid toward exit section, because of decreasing difference between surface and fluid temperature, the growth of temperature boundary layer increases and results in non-uniformity in temperature distribution in microchannel and cooling fluid. With decrease in the concentration from 0 to 0.1%, the average outlet temperature and FOM decrease nearby 0.62% and 6.15, respectively.

A pure and well crystalized yttrium doped hafnium oxide Hf0.69Y0.31O2-δ (YSH) is obtained by using a modified solid state reaction method, where a water-based milling medium and freeze drying are implemented to reduce the agglomeration. The mean sizes of the YSH powder, which is obtained through a traditional alcohol-based milling method, is more than 1 um. However, the powder size can be reduced to 100 nm by using the water-based milling method. In addition, the calcination temperature can be lowered 200 ℃ to get a pure phase by using the water-based milling method, compared to the alcohol-based milling method. The relative density of YSH ceramic materials can reach to 97.5% by conventional sintering at 1650 ℃ after during 10 h.