CSLM, XCT Couple interrogation of the emulsification interaction between free steel droplets suspended in steel making slags

Small Fe-based droplets have been heated to a molten phase suspended within a slag medium to replicate a partial environment within the Basic Oxygen Furnace (BOF). The confocal scanning laser microscope (CSLM) has been used as a heating platform as it offers the high heating rates necessary for slag and metal to become molten in close time proximity avoiding gradual equilibration during heating. The effect of impurities and their transfer across the metal/slag interface, on the emulsification of the droplet into the slag medium was then examined through X-ray Computer Tomography (XCT) scanning of the quenched sample. This gives the mapping of emulsion dispersion in 3D space, calculating the changing of interfacial area between the two materials, and changes of material volume due to material transfer between metal and slag. Samples were then sectioned and radial chemical analysis is used to identify component surface enrichment or lack thereof. Replication of the previously reported study by Assis et al1 has also been carried out, to show repeatability of the experimental set up and conditions through different users

Investigation into the cause of spontaneous emulsification of a free steel droplet : validation of the chemical exchange pathway

Small Fe-based droplets have been heated to a molten phase suspended within a slag medium to replicate a partial environment within the basic oxygen furnace (BOF). The confocal scanning laser microscope (CSLM) has been used as a heating platform to interrogate the effect of impurities and their transfer across the metal/slag interface, on the emulsification of the droplet into the slag medium. The samples were then examined through X-ray computer tomography (XCT) giving the mapping of emulsion dispersion in 3D space, calculating the changing of interfacial area between the two materials, and changes of material volume due to material transfer between metal and slag. Null experiments to rule out thermal gradients being the cause of emulsification have been conducted as well as replication of the previously reported study by Assis et al.[1] which has given insights into the mechanism of emulsification. Finally chemical analysis was conducted to discover the transfer of oxygen to be the cause of emulsification, leading to a new study of a system with undergoing oxygen equilibration

THE THERMODYNAMIC PROPERTIES OF VARIOUS LIQUID FERROUS ALLOYS

Abstract not availabl

THE THERMODYNAMIC PROPERTIES OF VARIOUS LIQUID FERROUS ALLOYS

Abstract not availabl

Sustainable Steelmaking Using Biomass and Waste Oxides (TRP9902)

A new process for ironmaking was proposed to employ renewable energy in the form of wood charcoal to produce hot metal. The process was aimed at the market niche of units ranging from 400,000 to 1 million tons of hot metal a year. In the new process, a Rotary Hearth Furnace (RHF) would be combined with a smelter to produce hot metal. This combination was proposed to overcome the technical hurdles of energy generation in smelters and the low productivity of RHFs, and also allow the use of wood charcoal as energy source and reductant. In order to assess the feasibility of the new process, it was necessary to estimate the productivity of the two units involved, the RHF and the smelter. This work concentrated on the development of a productivity model for the RHF able to predict changes in productivity according to the type of carbon and iron oxides used as feed materials. This model was constructed starting with the most fundamental aspect of reduction in composites measuring intrinsic rates of oxidation of different carbons in CO{sub 2}-CO atmospheres and reduction of different oxides in the same atmospheres. After that, a model was constructed considering the interplay of intrinsic kinetics and the transfer of heat to and within pellets such as used in the RHF. Finally, a productivity model for the RHF was developed based on the model developed for a pellet and the differences in heat transfer conditions between the laboratory furnace and the actual RHF. The final model produced for the RHF predicts production rates within 30% of actual plant data reported with coal and indicates that productivity gains as high as 50% could be achieved replacing coal with wood charcoal in the green balls owing to the faster reaction rates achieved with the second carbon. This model also indicates that an increase of less than 5% in total carbon consumption should take place in operations using wood charcoal instead of coal

Hydrogen and Nitrogen Control in Ladle and Casting Operations

In recent years there has been an increasing demand to reduce and control the amount of dissolved gases in steel. Hydrogen and nitrogen are two of the most important gases which when dissolved in liquid steel affect its properties significantly. Several steelmaking additions have been investigated in this research for their effect on the hydrogen and nitrogen content of steels. It has been established that calcium hydroxide (hydrated lime) acts as a source of hydrogen. Carburizers, such as metallurgical coke, were found to result in no hydrogen pickup when added to liquid steel. Addition of petroleum coke, on the other hand, increased the hydrogen content of liquid steel. Ferroalloy such as medium carbon ferromanganese when added to the liquid iron was found to increase its nitrogen content, the increase being proportional to the amount of ferroalloy added. Similarly, addition of pitch coke, which had a significant nitrogen impurity, increased the nitrogen content of liquid iron. A mathematical model was developed to quantify the absorption of nitrogen and hydrogen from the air bubbles entrained during tapping of liquid steel. During the bottom stirring of liquid metal in a ladle, the inert gas escaping from the top displaces the slag layer and often forms an open eye. The absorption of atmospheric nitrogen through the spout eye was estimated for different slag thickness and gas flow rate. The ultimate goal of this research was to develop a comprehensive set of equations which could predict the nitrogen and hydrogen pickup from their various sources. Estimates of hydrogen and nitrogen pickup during the steel transfer operations such as tapping and ladle stirring and the predicted pickup from steelmaking additions were integrated into empirical equations. The comprehensive model is designed to predict the gas pickup under varying operating conditions such as the metal oxygen and sulfur content, the total tapping or stirring time, the stirring gas flow rate and the slag thickness. The model predictions are based on mathematical and empirical evidence which are derived from thermodynamic and kinetic fundamental principles