| 1. |
- Malmberg, Donald, et al.
(författare)
-
Microwave Technology in Steel and Metal Industry, an Overview
- 2007
-
Ingår i: ISIJ International. - Tokyo : Nippon Tekko Kyokai. - 0915-1559 .- 1347-5460. ; 47:4, s. 533-538
-
Tidskriftsartikel (refereegranskat)abstract
- In many metallurgical operations, effective analysis of the processes can be very difficult with available technology. This is especially true if the analysis is to be performed on-line and in a harsh environment characterized by high temperatures, dust and liquid metal. Protection of the equipment requires both rugged encapsulation as well as elaborate sampling systems and exposure of the equipment to the hazardous environment must be minimised. Often this result in an increased level of service and maintenance requirements and, in the worst case, the maintenance cost might be so high that the equipment is not installed. Microwave technology is a versatile and powerful tool with many different applications in the scientific community. It is insensitive to dust and fume and, for several years, the technology has been tested at MEFOS and evaluated for different metallurgical processes. It has been applied to slag thickness measurement and slag composition in an induction furnace, 3D imaging of the burden surface in a charging model on pilot scale as well as raceway depth measurements in a Blast Furnace. The idea of using microwave technology for gas analysis in metallurgical processes has also been explored. However, despite its many advantages, microwave technology is still not employed extensively in the steel and metal industries. Copyright © 2007 ISIJ.
|
|
| 2. |
- Ahmed, Hesham, et al.
(författare)
-
Effect of added olivine on iron ore agglomerate during induration
- 2018
-
Ingår i: ISIJ International. - : Iron and Steel Institute of Japan. - 0915-1559 .- 1347-5460. ; 58:3, s. 446-452
-
Tidskriftsartikel (refereegranskat)abstract
- Olivine is used extensively in iron-pellet production as an additive in LKAB blast furnace pellets, in order to improve the high temperature properties of the finished product during reduction. As the contribution of olivine into the process depends on the available surface area, the present study was designed to find out the effect of olivine and its fineness on the oxidation-sintering and subsequent dissociation of olivine in iron ore agglomerates. Agglomerates were exposed to different experimental conditions to study the effect of olivine on the behavior of magnetite and hematite at high temperatures. Olivine particles were found to react significantly only above 1 000°C. Porosity of the final product was found to depend largely on olivine fineness. The finer the olivine the lower the porosity of the final product. It is found also that irrespective of the starting iron oxide the ratio between hematite and spinel phase was the same after heating in air. Olivine fineness affects significantly the rate of hematite dissociation, the finer the olivine the higher the dissociation rate. Upon cooling the weight lost due to the dissociation was again regained
|
|
| 3. |
- Ahmed, Hesham M., et al.
(författare)
-
Kinetics and Mathematical Modeling of Hydrogen Reduction of NiO-WO(3) Precursors in Fluidized Bed Reactor
- 2011
-
Ingår i: ISIJ International. - : Iron and Steel Institute of Japan. - 0915-1559 .- 1347-5460. ; 51:9, s. 1383-1391
-
Tidskriftsartikel (refereegranskat)abstract
- In the present work, Fluidized bed reduction of NiO-WO(3) precursors was investigated isothermally at temperatures 973-1 273 K. The reaction progress was monitored by analysis of H(2)O evolved during the reaction process using a gas chromatograph instrument. A theoretical model based on intrinsic chemical reaction rate constants and thermodynamic equilibria was developed to estimate the apparent reaction rate constant for the reduction reaction. In developing the model, the particles are considered to be in a completely mixed condition and gas flow is described as plug flow. The proposed model is also suitable for scale-up calculations. The interfacial chemical reaction model was found to fit the experimental results. The apparent activation energy values of the reduction process at different stages were calculated accordingly. The present investigation proved that the fluidized bed technique can be successfully utilized in bulk production of intermetallics containing W and a transition metal (or a composite material) wherein the process conditions would have a strong impact on the particle size of the end product.
|
|
| 4. |
- Ahmed, Hesham M., et al.
(författare)
-
On The Kinetics of Hydrogen Reduction of NiO-WO3 Precursors in Fluidized Bed- A Modeling Approach
- 2011
-
Ingår i: ISIJ International. - 0915-1559 .- 1347-5460. ; 51:9, s. 1383-1391
-
Tidskriftsartikel (refereegranskat)abstract
- In the present work, Fluidized bed reduction of NiO-WO3 precursors was investigated isothermally at temperatures 973-1 273 K. The reaction progress was monitored by analysis of H2O evolved during the reaction process using a gas chromatograph instrument. A theoretical model based on intrinsic chemical reaction rate constants and thermodynamic equilibria was developed to estimate the apparent reaction rate constant for the reduction reaction. In developing the model, the particles are considered to be in a completely mixed condition and gas flow is described as plug flow. The proposed model is also suitable for scale-up calculations. The interfacial chemical reaction model was found to fit the experimental results. The apparent activation energy values of the reduction process at different stages were calculated accordingly. The present investigation proved that the fluidized bed technique can be successfully utilized in bulk production of intermetallics containing W and a transition metal (or a composite material) wherein the process conditions would have a strong impact on the particle size of the end product.
|
|
| 5. |
- Ahmed, Hesham, et al.
(författare)
-
Reduction Behaviour of Self-reducing Blends of In-plant Fines in Inert Atmosphere
- 2015
-
Ingår i: ISIJ International. - 0915-1559 .- 1347-5460. ; 55:10, s. 2082-2089
-
Tidskriftsartikel (refereegranskat)abstract
- Large amount of dust and sludge recovered during cleaning of iron and steel making process gases are annually put on landfill or intermediate storage. These by-products have high contents of iron (Fe) and carbon (C) that potentially could be utilized in the steel industry. However, due to the presence of impuritycompounds as well as the unsuitable physical properties, these by-products cannot be recycled directly. The main objective of the present study is to investigate the possibilities to recover the valuable components Fe and C in these by-products and thereby decrease the need of landfills at the steel plants as well as reduce the consumption of virgin materials, including fossil coal, and reduce CO2 emissions. A recycling route has been investigated by means of laboratory trials and FactSage thermodynamic modeling. Four different blends of BF and BOF dusts and sludges are prepared in predetermined ratios. Reduction behavior of each blend is studied using TG/DTA/QMS and in-situ high temperature X-ray diffraction. High temperature physical properties like softening, swelling and melting are also investigated by means of heatingmicroscope. The obtained results indicate the feasibility of both minimizing the impurity elements as well as recovering of valuable components.
|
|
| 6. |
|
|
| 7. |
- Alexis, Jonas, et al.
(författare)
-
A model of an induction-stirred ladle accounting for slag and surface deformation
- 1999
-
Ingår i: ISIJ International. - 0915-1559 .- 1347-5460. ; 39:8, s. 772-778
-
Tidskriftsartikel (refereegranskat)abstract
- A 3 dimensional 2-phase model of an induction stirred ladle has been developed. The model is based on fundamental transport equations and includes the solution of steel- and slag-phase. Predicted velocities are in very good agreement with experimental data. Predicted velocities and turbulent kinetic energy dissipation from the model are shown to have linear relationships with input stirring force for different cylindrical ladles. Linear equations forthese relations are presented. Further calculations have shown that these linear equations also are able to predict velocities for a conical ladle. © 1999 ISIJ.
|
|
| 8. |
- Alexis, Jonas, et al.
(författare)
-
Heating and electromagnetic stirring in a ladle furnace – a simulationmodel
- 2000
-
Ingår i: ISIJ International. - : Iron and Steel Institute of Japan. - 0915-1559 .- 1347-5460. ; 40:11, s. 1098-1104
-
Tidskriftsartikel (refereegranskat)abstract
- A three-dimensional simulation model coupling heating and induction stirring in an ASEA-SKF ladle furnace was developed. Data of the heat transfer from the area to the steel bath were predicted in a separate model and included as boundary conditions in a ladle model. The are model considers the contributions of heat transferred by of each of the following mechanisms: radiation, convection, condensation and energy transported by electrons. Predictions were made to simulate the change of temperature distribution in the ladle during simultaneous heating with electrodes and stirring by induction. A first attempt was made to compare the predictions with measured temperatures from a 100 t ASEA-SKF ladle. The agreement was found to be fairly good when heat-flux data for a 25 cm are length were used as input to the ladle model. This indicates that the model can be used for more in-depth studies of the effects of heating for ladles that are inductively stirred.
|
|
| 9. |
- Alexis, J., et al.
(författare)
-
Modeling of a DC electric arc furnace - Heat transfer from the arc
- 2000
-
Ingår i: ISIJ International. - : Iron and Steel Institute of Japan. - 0915-1559 .- 1347-5460. ; 40:11, s. 1089-1097
-
Tidskriftsartikel (refereegranskat)abstract
- A mathematical model describing heat and fluid flow in an electric are has been developed and used to predict heat transfer from the are to the steel bath in a DC Electric Are Furnace. The are model takes he separate contributions to the heat transfer from each involved mechanism into account, i.e. radiation, convection, condensation and energy transported by electrons. The model predicts heat transfer for different currents and are lengths. Model predictions show that are efficiency is higher for lower power input. The model also predicts shear stresses and current density distribution at the steel surface. This information can be used as boundary condition input to simulate the effect of heating with electrodes in a DC EAF on the heat and fluid flow in the steel bath.
|
|
| 10. |
- Andersson, Anton, et al.
(författare)
-
Characterization and Upgrading of a Low Zinc-Containing and Fine Blast Furnace Sludge : A Multi-Objective Analysis
- 2017
-
Ingår i: ISIJ International. - : The Iron and Steel Institute of Japan. - 0915-1559 .- 1347-5460. ; 57:2, s. 262-271
-
Tidskriftsartikel (refereegranskat)abstract
- Ore-based steelmaking generates a variety of residues including dusts, sludges and slags. Recycling of these residues within the process or via other applications is essential for sustainable production from both environmental and economic aspects. In blast furnace (BF) ironmaking, there are generally two residues leaving the gas cleaning equipment; namely, BF dust and BF sludge. Traditionally, the dust is recycled via the sinter or, in the case of pellet based BF, via cold bonded agglomerates and injection. As the main output of zinc from the BF is the top gas, the sludge has to be dezinced prior to recycling to prevent accumulation of zinc in the furnace. Although dezincing of BF sludge has been successfully accomplished using e.g., hydrocycloning, the studied sludges are generally coarse sized and high in zinc. Furthermore, information is lacking regarding the efficiency of separation of different hydrocyclone setups. In the present work, hydrocycloning of a fine sludge, with low zinc content, generated by a pellet based BF has been studied. The gas cleaning equipment used to produce the sludge was running a primary aerocyclone and a scrubber. A characterization of the sludge has been conducted together with an evaluation of the separation efficiency of the hydrocyclone in order to assess the hydrocyclone performance and limitations. Furthermore, the dezincing using the hydrocyclone has been compared to that of sulfuric acid leaching. The results suggest that 51 to 93% of the sludge can be recycled depending on the demand on zinc removal and the chosen dezincing route.
|
|
