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  • 1.
    Davydenko, Arkadiy
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Glaser, Bjoern
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Direct Reduction of Fe, Ni and Cr from Oxides of Waste Products Used in Briquettes for Slag Foaming in EAF2019In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, no 20, article id 3434Article in journal (Refereed)
    Abstract [en]

    Environmental aspects and the sustainable manufacturing of steels require producers to pay more and more attention to the efficient utilization of materials and waste products during steelmaking. This study is focused on the evaluation of possibilities for the recovery of metals (such as Fe, Ni and Cr) from waste products used for slag foaming in the Electric Arc Furnace (EAF) process. Two types of industrial briquettes were produced by mixing mill-scale from the hot rolling of stainless steels with anthracite and pet-coke, respectively. Thereafter, an assessment of the metal reduction processes in briquettes at high temperatures (1500 degrees C) was made by using laboratory thermo-gravimetric reduction experiments in an argon atmosphere. The amounts of metal, slag and gas obtained from the briquettes were estimated. In addition, the velocity and time for the removal of metal droplets from the liquid slag depending on the size of the metal droplets was estimated. It was found that up to 97% of metal droplets can be removed from the slag during the first 30 min. Moreover, results showed that most of the Cr, Ni and Fe (up to 93-100%) can be reduced from oxides of these metals in briquettes at 1500 degrees C. Moreover, the anthracite and pet-coke in the investigated briquettes have similar reduction capabilities. It was found that up to 330 kg of Fe, 28 kg of Ni and 66 kg of Cr per ton of added briquettes can be recovered from waste products by the industrial application of those briquettes for slag foaming in EAF.

  • 2.
    Deng, Tengfei
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Glaser, Björn
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Sichen, Du
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Experimental Design for the Mechanism Study of Lime Dissolution in Liquid Slag2012In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 83, no 3, p. 259-268Article in journal (Refereed)
    Abstract [en]

    The applicability of rotating rod technique in the study of lime dissolution in slag was investigated. Both computational fluid dynamic (CFD) and cold model experiments showed that the mass transfer due to radial velocity introduced by forced convection was zero if the rod was long. The mass transfer by forced convection was also less important in comparison with natural convection and diffusion when the rod was half length of the height of the bath. This finding was in accordance with the criteria put forward by the original work that the method could only be applicable when a thin disk (instead of rod) with big diameter and big liquid bath were used. To study the lime dissolution by forced convection a new experimental technique was developed. A cube was placed in the slag that was eccentrically stirred. The whole system, viz. the sample along with the slag could be quenched. The new technique could study the effect of forced convection on the dissolution. The microscopic study on the quenched slag-lime samples could reveal the dissolution mechanism successfully.

  • 3.
    Deng, Zhiyin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Glaser, Bjoern
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Bombeck, M. A.
    Du, Sichen
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Study on the blocking of ladle well due to sintering of filler sand2015In: Proceedings of the 6th International Congress on the Science and Technology of Steelmaking, ICS 2015, Chinese Society for Metals , 2015, p. 529-532Conference paper (Refereed)
    Abstract [en]

    The present work aimed at a mechanism study of blocking of ladle well by filler sand. Laboratory experiments were carried out using two different chromite based filler sands technically proven. The interaction between the liquid steel and the sand was also studied by using steels containing different contents of Mn and Al. The reaction between the silica phase and the chromite phase was found to be the main mechanism for the sintering of sand. The reaction resulted in a liquid oxide phase, which became the binding phase between the solid oxide grains. The size of silica phase was found to have great impact on the formation of the liquid oxide phase. Faster formation of the liquid oxide phase would lead to more serious sintering of the sand. It was found that the presence of liquid steel enhanced considerably the sintering of the sand and even increased the amount of liquid phase. Higher temperature and longer holding time would make the sintering of the sand more seriously.

  • 4.
    Deng, Zhiyin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Glaser, Björn
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Bombeck, M. A.
    Sichen, Du
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Mechanism Study of the Blocking of Ladle Well Due to Sintering of Filler Sand2015In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344XArticle in journal (Refereed)
    Abstract [en]

    The present work is aimed at a mechanism study of blocking of ladle well by filler sand. Laboratory experiments are carried out using two different chromite-based filler sands. The interaction between the liquid steel and the sand is also studied by using steels containing different contents of Mn and Al. The reaction between the silica phase and the chromite phase is found to be the main mechanism for the sintering of sand. The reaction results in a liquid oxide phase, which becomes the binding phase between the solid oxide grains. The amount of silica phase and its grain size are found to have great impact on the formation of the liquid oxide phase. Faster formation of the liquid oxide phase leads to more serious sintering of the sand. It is found that liquid steel can hardly infiltrate into sand. On the other hand, the presence of steel considerably increases the amount of liquid phase and enhances the sintering of the sand.

  • 5.
    Deng, Zhiyin
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling. School of Metallurgy, Northeastern University, China.
    Glaser, Björn
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Bombeck, Marc André
    PURMETALL GmbH & Co. KG, 46049 Oberhausen, Germany.
    Du, Sichen
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Effects of Temperature and Holding Time on the Sintering of Ladle Filler Sand with Liquid Steel2016In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 87, no 7, p. 921-929Article in journal (Refereed)
    Abstract [en]

    In the present work the effects of temperature and holding time on the sintering of ladle filler sand are studied. Laboratory experiments are carried out using pellets made of chromite based filler sand and two steel grades containing different contents of Mn and Al. It is found that the liquid steel plays a major role in the sintering behavior. The results also show that the amount of liquid phase in the sintered sand pellets increases with the increase of temperature and holding time. The Al2O3 content increases substantially in the chromite phase (spinel), especially in the region close to the liquid phase, when the temperature is high enough or when the holding time is long enough. Higher content of dissolved Al would accelerate the formation of the alumina-rich chromite.

  • 6.
    Glaser, Bjoern
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Gornerup, Marten
    Du, Sichen
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Fluid Flow and Heat Transfer in the Ladle during Teeming2011In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 82, no 7, p. 827-835Article in journal (Refereed)
    Abstract [en]

    A two dimensional axisymmetric model was developed to predict the heat flux in a steelmaking ladle during the teeming process. The model predicts dynamically the flow fields in both liquid phase and gas phase along with the movement of the liquid upper surface. The model also predicts the temperature distributions in the liquid metal, gas phase and all layers in the ladle wall. Industrial measurements using infrared radiation camera inside the ladle after teeming and at the wall outside the ladle during the whole process were carried out. The model predictions were found to be in agreement with the measured data. It was found that the heat transfer to the surrounding atmosphere and the conductivity of the highly insulating layer were the most important factors for the heat loss. The decrease of the thickness of the working lining was found to have limited effect on the total heat flux.

  • 7.
    Glaser, Björn
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    A Study on the Thermal State of Steelmaking Ladles2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In the present thesis a study on the thermal state of steelmaking ladles was undertaken. The transient hot wire method was verified for thermal conductivity measurements on metallurgical slags and applied to ladle slag measurements. Temperature measurements on ladles in an industrial environment were carried out. The emissivities of the outer and inner shells of steelmaking ladles were investigated. Two dynamic models were developed to predict the heat transfer and fluid flow in a preheating and teeming ladle. The gathered thermal conductivity values for ladle slag were used to study the effect of the slag layer on the top surface of the melt on heat transfer and fluid flow in a teeming ladle.

    In the first stage, the transient hot-wire method was verified to measure the thermal conductivity of metallurgical slags at steelmaking temperatures. A numerical model was developed, cold model experiments were conducted and test measurements using a high temperature experimental setup were carried out. To minimize natural convection and to obtain more reliable measurements, the crucible diameter, the hot-wire diameter, the applied current, the position of the wire in the crucible and the cooling on the upper surface of the crucible were studied. Investigations into the choice of sheathing material of the circuit exposed to the slag were also made. It was found that only certain materials were suitable for slag measurements depending on slag composition and temperature. The electrical resistivity of the hot wire was measured to make the thermal conductivity calculation more reliable. The wire diameter also played a major role due to the heat generation per surface area. The thermal conductivity should be derived from the values measured during the first seconds. In this initial stage, the effect of the natural convection as a function of the wire position in the crucible, the cooling on the top surface and the diameter of the crucible are negligible. A compromise has to be made in choosing the electrical current, since higher current results in higher sensitivity but at the same time in more natural convection.

    In the second stage, the thermal conductivities of four different ladle slags were measured at 1773 K, 1823 K, 1873 K and 1923 K using the transient hot wire method. Very good reproducibility was obtained. The thermal conductivity did not vary substantially with the variation of slag composition at 1873 K and 1923 K, at which the slag samples were all entirely liquid. The thermal conductivities were low. It was found that the precipitation of solid phase resulted in a considerable increase of thermal conductivity.

    In the third stage, a two dimensional model was developed in order to predict the temperature distribution in the ladle wall during the preheating process. The model calculated the heat transfer and the velocity field in the gas phase inside the ladle as well as the heat transfer in the solid walls during the preheating process. Measurements of the temperature profiles in an industrial ladle were carried out using an infrared thermography. The measurements were made both inside and outside the ladle. The model predictions were found to be in reasonably good agreement with the measured temperatures. It was found that the preheating time could be minimized when the working lining became thinner. The effect ofthe distance between the lid and the ladle was also studied by the model. The results indicated that there was no significant temperature change on the upper side wall of the ladle. On the lower side wall and bottom the temperature changed slightly. The temperature difference in the lower part of the ladle could be explained by the larger flame distance from the bottom layer.

    In the fourth stage, a two dimensional axisymmetric model was developed to predict the heat flux in a steelmaking ladle during the teeming process. The model predicts dynamically the flow fields in both the liquid phase and the gas phase along with the movement of the liquid upper surface. The model also predicts the temperature distributions in the liquid metal, gas phase and all layers in the ladle wall. Again, industrial measurements were performed using an infrared thermography, both inside the ladle after teeming and at the wall outside the ladle during the whole process sequence. The model predictions were found to be in agreement with the measured data. It was found that the heat transfer to the surrounding atmosphere and the conductivity of the highly insulating layer were the most important factors for the heat loss. The decrease of the thickness of the working lining was found to have limited effect on the total heat flux.

    In the fifth and final stage, the effect of the slag layer on the top surface of the melt, on fluid flow and on heat transfer in a teeming ladle was investigated theoretically. The two dimensional axisymmetric model developed in the fourth stage was used. To predict the effect of the slag layer a stationary heat conduction boundary condition including thermal conductivity and slag layer thickness was employed. Different calculations with differing thermal conductivity values for the slag layer were carried out. The calculations showed that the effect of the slag layer was insignificant. This could be explained by the similarity of the thermal conductivity of slag and gas phase.

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  • 8.
    Glaser, Björn
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    The effect of the slag layer on fluid flow and heat transfer in a teeming ladleManuscript (preprint) (Other academic)
  • 9.
    Glaser, Björn
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Görnerup, Mårten
    Metsol AB.
    Sichen, Du
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Thermal Modelling of the Ladle Preheating Process2011In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 82, no 12, p. 1425-1434Article in journal (Refereed)
    Abstract [en]

    To predict the temperature distribution in the ladle wall during the preheating process a two dimensional model was developed. The model calculated the heat transfer and the velocity field in the gas phase inside the ladle as well as the heat transfer in the solid walls during the preheating process. Measurements of the temperature in an industrial lade were carried out using an infrared radiation (IR) camera. The measurements were made inside and outside the ladle. The model predictions were found to be in reasonably good agreement with the measured temperatures. It was found that the preheating time could be minimized when the working lining became thinner. The effect of the distance between the lid and the ladle was also studied by the model. The results indicated that there was no significant temperature change on the upper side wall of the ladle. On the lower side wall and bottom the temperature changed slightly. The temperature difference in the lower part of the ladle could be explained by the larger flame distance from the bottom layer.

  • 10.
    Glaser, Björn
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Ma, Luyao
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Sichen, Du
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Determination of Experimental Conditions for Applying Hot Wire Method to Thermal Conductivity of Slag2013In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 84, no 7, p. 649-663Article in journal (Refereed)
    Abstract [en]

    In order to apply the hot wire method for metallurgical slags at steelmaking temperatures, a numerical model was developed, cold model experiments were conducted and test measurements using a high temperature experimental setup were carried out. To minimize natural convection and obtain more reliable measurements, the crucible diameter, the hot-wire diameter, the applied current, the position of the wire in the crucible, and the cooling on the upper surface of the crucible were studied. Investigations into the choice of sheathing material of the circuit exposed to the slag were also made. It was found that only certain materials were suitable for slag measurements depending on slag composition and temperature. The electrical resistivity of the hot wire was measured to make the thermal conductivity calculation more reliable. The wire diameter also played a major role, because of the heat generation per surface area. The thermal conductivity should be derived from the values measured during the first seconds. In this initial stage, the effect of the natural convection as a function of the wire position in the crucible, the cooling on the top surface, and the diameter of the crucible are negligible. A compromise has to be made in choosing the electrical current, since higher current results in higher sensitivity but at the same time in more natural convection.

  • 11.
    Glaser, Björn
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Sichen, Du
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Thermal Conductivity Measurements of Ladle Slag Using Transient Hot Wire Method2013In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 44, no 1, p. 1-4Article in journal (Refereed)
    Abstract [en]

    Thermal conductivities of four different ladle slags were measured at 1773 K, 1823 K, 1873 K, and 1923 K (1500 A degrees C, 1550 A degrees C, 1600 A degrees C, and 1650 A degrees C) using the transient hot wire method. Very good reproducibility was obtained. The thermal conductivity did not vary substantially with the variation of slag composition at 1873 K and 1923 K (1600 A degrees C and 1650 A degrees C), at which the slags were all entirely liquid. The thermal conductivities were low. It was found that the precipitation of solid phase resulted in considerable increase of thermal conductivity.

  • 12.
    Kazemi, Mania
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Glaser, Bjoern
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Sichen, Du
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Study on Direct Reduction of Hematite Pellets Using a New TG Setup2014In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 85, no 4, p. 718-728Article in journal (Refereed)
    Abstract [en]

    A new thermogravimetric setup was developed to study direct reduction of iron oxide under well-controlled experimental conditions. Pure and industrial hematite samples were isothermally reduced by hydrogen and carbon monoxide gaseous mixtures. Influences of gas composition, gas flow rate, and temperature on reduction were investigated. Reduction rates obtained using the new setup were higher compared to conventional thermogravimetric method. This difference was due to the time required to replace the inert gas with the reactant gas in the conventional method, which led to lower reduction rate at the initial stage. Carbon deposited on the surface of the pellets at relatively high gas flow rates and at low temperatures. The presence of pure iron and high carbon potential in the gas phase were the cause for carbon deposition. Study of partially reduced samples illustrated that the outer layer of pellet with high iron content thickened as reduction proceeded inside the pellet. Closure of micro-pores and formation of dense iron phase in this layer decelerated diffusion of reactant and product gases, and led to decrease of reduction rate at later stages of reaction. At lower temperatures, this effect was coupled with carbon deposition. Therefore, the reduction was seriously hindered.

  • 13.
    Lindström, David
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Nortier, Patrice
    Glaser, Björn
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Sichen, Du
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Study on the Possibility of Using ZnO for Hot Metal Desulfurization2013In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 84, no 5, p. 419-425Article in journal (Refereed)
    Abstract [en]

    The possibility of using ZnO for desulfurization in hot metal was evaluated. A lab scale experimental setup was designed so that different desulfurizing agents could be added to hot metal for evaluation of their desulfurizing power. The setup had good control of both temperature and the gaseous atmosphere. It also provided stirring of the metal bath with an impeller as well as quenching facility to maintain the metal composition at high temperature. Desulfurization of hot metal using CaO powder showed evidently the applicability of the new setup. On the other hand, additions of ZnO into the hot metal under various experimental conditions showed no effect on desulfurization. The results were in contradiction to the suggestion found in literature. A thorough examination of the thermodynamic data employed by the previous work was carried out. The data used in the literature were found to be subjected to fundamental mistakes. The present experimental results convincingly rule out the possibility of using ZnO as a desulfurization agent.

  • 14.
    Martinsson, Gustav
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Centres, Centre of Excellence for Science and Innovation Studies, CESIS.
    Glaser, Bjoern
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Sichen, Du
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Lime Dissolution in Foaming BOF Slag2018In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 49, no 6, p. 3164-3170Article in journal (Refereed)
    Abstract [en]

    The paper describes the dissolution mechanisms of lime into liquid and foaming slags relevant to the BOF process. Two different master slags are employed, representing two different periods of the converter process: an early stage where the FeO content is fixed to 45 wt pct, and a later stage where the FeO content is fixed to 25 wt pct. For these master slags, the ratio between CaO/SiO2 is varied to examine the effect of basicity on lime dissolution. Calcium silicates are formed and peeled off, or partially peeled off, from the interface between the lime cube and the slag in all cases. The main difference for the dissolutions in pure liquid slag and foaming slag is the controlling step for dissolution. In liquid slag, the controlling mechanism is the removal of the calcium silicate layers, while in foaming slag, the controlling mechanism is the contact area between the lime and the liquid slag phase of the foam. The strong convection in the foam enhance the dissolution process, in some cases, the lime even dissociates into small pieces.

  • 15.
    Martinsson, Johan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Glaser, Bjoern
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Sichen, Du
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    The structure of foaming BOF-converter slag2017In: IRONMAKING & STEELMAKINGArticle in journal (Other academic)
  • 16.
    Martinsson, Johan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Glaser, Bjoern
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Sichen, Du
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    The structure of foaming BOF-converter slag2019In: Ironmaking & steelmaking, ISSN 0301-9233, E-ISSN 1743-2812, Vol. 46, no 8, p. 777-781Article in journal (Refereed)
    Abstract [en]

    The structure of foaming synthetic BOF-converter slags was studied by freezing the foam and using ocular examination. The foams were generated by CO gas formed due to the reaction between FeO in the slag and carbon in the hot metal. The character of the foams varied a lot with slag composition. Slag with lower viscosity resulted in foams with small gas bubbles, while slag having high viscosity resulted in very big bubbles.

  • 17.
    Martinsson, Johan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Glaser, Björn
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Sichen, Du
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Study on Apparent Viscosity and Structure of Foaming Slag2016In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 47, no 5, p. 2710-2713Article in journal (Refereed)
    Abstract [en]

    Foaming slag was generated using induction heating. The foam was found non-Newtonian having much higher apparent viscosity compared to the dynamic viscosity of pure slag. Quenched foam was examined. The appearance of the foaming slag was very different from silicone oil-gas foam. The size of gas bubbles ranged from 0.1 to 4 mm (while in the case of silicone oil, 1 to 2 mm). The gas fraction in the foam was considerably lower than in the case of silicone oil.

  • 18.
    Martinsson, Johan
    et al.
    KTH, School of Industrial Engineering and Management (ITM).
    Glaser, Björn
    KTH, School of Industrial Engineering and Management (ITM).
    Sichen, Du
    KTH, School of Industrial Engineering and Management (ITM).
    Study on apparent viscosity of foaming slag – Cold model and high temperature experiments2017In: Advances in Molten Slags, Fluxes, and Salts: Proceedings of the 10th International Conference on Molten Slags, Fluxes and Salts 2016, Springer International Publishing AG , 2017, p. 431-438Conference paper (Refereed)
    Abstract [en]

    The apparent viscosities of foaming silicon oil and foaming slag was measured. In both studies, the rotating cylinder method was used for the measurements. Additionally, the movement of particles in foaming silicon oil and the behavior of pig iron droplets in foaming slag was investigated. An increase of the apparent viscosity compared to the dynamic viscosity could be observed. The apparent viscosities decreased with increasing rotation speed of the spindle. The moving particles in the foaming silicon oil gave reasonable information regarding the behavior of particles and droplets in foam. This information are needed to get a better understanding of the behavior of iron droplets in foaming slag. After high temperature experiments, the pig iron droplets were collected and analyzed. Conclusions were made regarding mass transfer between foaming slag and iron droplets.

  • 19.
    Martinsson, Johan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Sichen, Du
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Glaser, Bjoern
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Lime dissolution in liquid versus foaming BOF slagManuscript (preprint) (Other academic)
  • 20.
    Nabeel, Muhammad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Glaser, Bjoern
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Characterization of Dust Generated during Mechanical Wear of Partially Reduced Iron Ore Pellets2017In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 88, no 9, article id UNSP 1600442Article in journal (Refereed)
    Abstract [en]

    During reduction in a blast furnace (BF), the iron ore pellets undergo structural changes, which facilitate dust generation due to the mechanical wear/disintegration of the pellets. The generated dust decreases the permeability and productivity of the BF process. Thus, this study investigates the mechanical wear of iron ore pellets reduced at 500 degrees C (P500) and 850 degrees C (P850) and compares the results to the wear of unreduced pellets (P25). Moreover, the dust generated during the wear experiments is also characterized. It is found that pellets reduced at 500 degrees C exhibit a approximate to 16-35% higher wear rate than reference unreduced pellets. For the pellets reduced at 850 degrees C, the mechanical wear is inhibited by a formation of a metallic layer at the outer surface of the pellets. Further, the dust generated due to mechanical wear of reduced pellets contain 3-6 times higher amount of coarse particles (>20m) as compared to the dust from unreduced pellets. The obtained results are explained on the basis of the structural changes, which take place during the reduction of pellets.

  • 21.
    Nabeel, Muhammad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Glaser, Bjoern
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Characterization of dust generated during mechanical wear of partially reduced iron ore pelletsManuscript (preprint) (Other academic)
    Abstract [en]

    During reduction in a blast furnace (BF), the iron ore pellets undergo structural changes which facilitate dust generation due to the mechanical wear / disintegration of the pellets. The generated dust decreases the permeability and productivity of the BF process. Thus, this study investigates the mechanical wear of iron ore pellets reduced at 500 °C (P500) and 850 °C (P850) and compares the results to the wear of unreduced pellets (P25). Moreover, the dust generated during the wear experiments is also characterized. It was found that pellets reduced at 500 °C exhibit a ~ 16 to 35% higher wear rate than reference unreduced pellets. For the pellets reduced at 850 °C, the mechanical wear is inhibited by a formation of a metallic layer at the outer surface of the pellets. Further, the dust generated due to mechanical wear of reduced pellets contained 3 to 6 times higher amount of coarse particles (>20µm) as compared to the dust from unreduced pellets. The obtained results are explained on the basis of the structural changes which take place during the reduction of pellets. 

  • 22.
    Wang, Huijun
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Glaser, Bjoern
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Sichen, Du
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Improvement of Resistance of MgO-Based Refractory to Slag Penetration by In Situ Spinel Formation2015In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 46, no 2, p. 749-757Article in journal (Refereed)
    Abstract [en]

    MgO-in situ spinel substrate was prepared at 1773 K (1500 degrees C) using colloidal alumina suspension and coarse MgO as raw materials. While the addition of 10 mass pct colloidal alumina had limited effect, addition of 20 mass pct colloidal alumina into the MgO matrix improved greatly the resistance of the substrate against the slag penetration at 1873 K (1600 degrees C). The improvement was found to be mainly related to the formation of solid phases, CaO center dot Al2O3 and CaO center dot MgO center dot Al2O3 at the grain boundaries due to slag-spinel reaction. Putting the reacted substrate into contact again with new slag revealed no appreciable new slag penetration. The results showed a potential solution to improve the resistance of MgO-based refractory to slag penetration and to improve steel cleanness.

  • 23.
    White, Jesse F.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Lee, Jaewoo
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Hessling, Oscar
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Glaser, Björn
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Reactions Between Liquid CaO-SiO2 Slags and Graphite Substrates2017In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 48, no 1, p. 506-515Article in journal (Refereed)
    Abstract [en]

    In this study, the spreading and infiltration behavior of liquid slag in contact with different grades of graphite was investigated. The wetting and infiltration of slag into graphite were found to be highly material dependent. The reduction of silica by carbon is a characteristic of the system, and it generates gaseous products as evidenced by the observation of bubble formation. The higher the temperature and silica activity of the slag is, the greater the slag infiltration and the faster the rate of spreading. Silicon infiltrated into the graphite substrates much deeper than the oxide phases, indicating gas-phase transport of SiO(g) into the graphite pores. Fundamentally, in this system where the liquid and substrate are reacting, the driving force for spreading is the movement of the system toward a lower total Gibbs energy. Reduction of silica in the slag near the interface may eventually lead to the formation of a solid, CaO-rich layer, slowing down or stopping the reduction reaction.

  • 24.
    White, Jesse
    et al.
    KTH, School of Industrial Engineering and Management (ITM).
    Lee, Jaewoo
    KTH.
    Hessling, Oscar
    KTH.
    Glaser, Bjoern
    KTH, School of Industrial Engineering and Management (ITM).
    Interactions between liquid CaO–SiO2 slags and graphite substrates2017In: Advances in Molten Slags, Fluxes, and Salts: Proceedings of the 10th International Conference on Molten Slags, Fluxes and Salts 2016, Springer International Publishing AG , 2017, p. 565-572Conference paper (Refereed)
    Abstract [en]

    In this study, the spreading and infiltration behavior of slag in contact with different grades of graphite was investigated. The wetting and infiltration of slag into graphite were found to be highly material dependent. Temperature and silica content of the slag also have a major influence on how slag spreads and infiltrates: The higher the temperature and silica content, the greater the slag infiltration, and the faster the rate of spreading. Reactions that generate gaseous products occurred during spreading of slag on graphite was evidenced by the observation of bubble formation. Silicon infiltrated into the graphite substrates much deeper than the slag phase, indicating gas-phase transport of silicon-bearing vapor species. Complete wetting of the interface and reduction of silica in the slag near the interface may lead to passivation by formation of a solid, CaO-rich layer.

  • 25.
    Yan, Baijun
    et al.
    Univ Sci & Technol Beijing, Sch Met & Ecol Engn, Dept Phys Chem Met, Beijing 100083, Peoples R China..
    Liu, Yixiang
    Univ Sci & Technol Beijing, Sch Met & Ecol Engn, Dept Phys Chem Met, Beijing 100083, Peoples R China..
    Shu, Qifeng
    Univ Sci & Technol Beijing, Sch Met & Ecol Engn, Dept Phys Chem Met, Beijing 100083, Peoples R China..
    Deng, Tengfei
    Wuhan Univ Technol, State Key Lab Silicate Mat Architectures, Wuhan 430070, Hubei, Peoples R China..
    Glaser, Björn
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Measurements and Model Estimations of Viscosities of the MnO-CaO-SiO2-MgO-Al2O3 Melts2019In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 50, no 1, p. 376-384Article in journal (Refereed)
    Abstract [en]

    The viscosities of the MnO (0 to 55 mass pct)-CaO-SiO2-MgO (5 mass pct)-Al2O3 (20 mass pct) melts were measured by rotating cylinder method in the temperature range from 1573 K to 1873 K (1300 degrees C to 1600 degrees C). The measurements were carried out in the atmosphere of flowing CO/CO2 gas mixture with a volume ratio of 99/1, and molybdenum crucible and spindle were adopted. The results reveal that MnO is a viscosity reducing component, and the effect of MnO is more notable in the melts with higher ratio of CaO to SiO2. For example, in the melts with the mass ratio of CaO to SiO2 equal to 0.6, the addition of 5 mass pct MnO only slightly reduced the viscosities. Comparatively, the addition of 5 mass pct MnO made the viscosities of the melts with the mass ratio of CaO to SiO2 equal to 1.0 and 1.5 decrease remarkably. Based on the measured data, the viscosities estimation model proposed in our previous study was extended to the system containing MnO, and the model parameters were determined. The model can estimate and predict the viscosities of the aluminosilicate melts containing MnO well, and then some iso-viscosity contours of this system were calculated. From the iso-viscosity contours, it can be seen that MnO is almost equivalent to CaO in reducing the viscosities in the melt with high SiO2 content, while with the decrease of the SiO2 content MnO becomes more effective than CaO.

  • 26.
    Zhao, Zengwu
    et al.
    Inner Mongolia Univ Sci & Technol, Inner Mongolia Key Lab Utilizat Bayan Obo Multime, Elected State Key Lab, Baotou 014010, Peoples R China..
    Chen, Xuexin
    Univ Sci & Technol Beijing, Dept Phys Chem Met, Beijing 100083, Peoples R China..
    Glaser, Björn
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Yan, Baijun
    Univ Sci & Technol Beijing, Dept Phys Chem Met, Beijing 100083, Peoples R China..
    Experimental Study on the Thermodynamics of the CaO-SiO2-Ce2O3 System at 1873 K2019In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 50, no 1, p. 395-406Article in journal (Refereed)
    Abstract [en]

    The phase relations in the CaO-SiO2-Ce2O3 system under the reducing atmosphere at 1873 K were determined by the conventional equilibrium and quenching method combined with scanning electron microscopy-electron probe microanalysis (SEM-EPMA) and X-ray diffraction (XRD) measurements on the quenched samples. Based on these analyses, a large part of the isothermal phase diagram was constructed. Furthermore, the thermodynamic activities of Ce2O3 in the melts at 1873 K were measured by the chemical equilibrium method. Using the measured activity data, an empirical formula to estimate the activity coefficient of Ce2O3 was proposed based on the regular solution model. It was found that, for the melts with the same Ce2O3 contents, the thermodynamic activities of Ce2O3 increase gradually with the rise of basicity (the ratio of CaO to SiO2) of the melts. This implies that, from the thermodynamic point of view, the increase of basicity is favorable to the enrichment and precipitation of Ce-containing mineral phases.

1 - 26 of 26
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