Thesis: B.S., Massachusetts Institute of Technology, Department of Metallurgy, 1966 / Bibliography: leaf 37. / B.S. / B.S. Massachusetts Institute of Technology, Department of Metallurgy

The ladle metallurgical furnace (LMF) is a very flexible and common unit operation found in most steelmaking melt shops, and enables the adjustment and fine-tuning of molten steel's composition and temperature prior to casting. Despite the importance of ladle metallurgy to the overall steel making process very little has been achieved in the way of advanced ladle control. Limited sensors are available to monitor heat progress during refining and current control methods involve manual procedures. This thesis represents part of an ongoing study on the modelling of a full-scale LMF in real-time with the forward goal of improved control and optimization. The first part of this thesis details a vision-based sensor for analyzing ladle eye dynamics online using a multivariate image analysis (MIA) technique based on principal component analysis (PCA). Predictive capabilities of the developed model are demonstrated using previously published cold model data over a wide range of operating variables. Further, preliminary work has confirmed the ability of the sensor for potential use in an industrial setting. The second part of this study concerns the development of metallurgical models for assessing the state of a ladle metallurgical furnace. Specifically, a multi-component kinetic model in combination with developed slag and steel thermodynamic solution models were used to quantitatively describe the kinetics of slag-metal reactions within 41 industrially sampled heats at ArcelorMittal Dofasco's LMF#2. Metal phase mass transfer coefficients for all elements in steel were assumed to follow the empirical relation derived from measured sulphur contents, while slag phase mass transfer coefficients were calculated by fitting the ratio of k^Mm/ k^MxOysl to the experimental results. On the basis of the fitted results, slag phase mass transfer coefficient correlations were evaluated using linear regression. Computed results from the model using these slag phase mass transfer coefficient correlations were found to be consistent with the experimental data. In regard to the developed thermodynamic solution models, original contributions to the modified interaction parameter formalism and cell model are presented. As process model predictions are invariably uncertain, the final part of this work involves the use of a stochastic model (extended Kalman filter) to account for process disturbances, model-mismatch and other sources of uncertainty that may result in significant error propagation causing poor process control and plant economics. Several case studies were performed to illustrate the effectiveness of the extended Kalman filter and its application to optimal sensor selection was introduced. / Thesis / Doctor of Philosophy (PhD)

With the rapidly increasing importance placed by industry upon the development, treatment, examination and testing of metals and their alloys, there follows increasing stress on sound fundamentale in metallurgical laboratory practice as employed by the student majoring in this field. Following a study of the requirements which must usually be met by the graduate who intends to continue his work in metallurgy, a series of experiments has been carefully planned, performed, and thoroughly studied to determine their value to the student. This work was done under the direction and direct supervision of Professor H. V. White, Head of the Department of Metallurgical Engineering of Virginia Polytechnic Institute, and with the facilities of the laboratory under his charge. General instructions in the selected experiments and typical laboratory reports are contained in the pages which follow. Since a large part of the experimental work was done with laboratory equipment developed for these specific experiments, description of apparatus and certain explanations are included in Section II, Experiment Reports. / Master of Science

DISSERTATION (PH.D.)--THE UNIVERSITY OF MICHIGAN

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This investigation has been concerned with the behaviour of solid internal lubricant during mixing, compaction, ejection, dewaxing and sintering of iron powder compacts. Zinc stearate (0.01%-4.0%) was added to irregular iron powder by admixing or precipitation from solution. Pressure/density relationships, determined by continuous compaction, and loose packed densities were used to show that small additions of zinc stearate reduced interparticle friction during loose packing and at low compaction pressures. Large additions decreased particle/die-wall friction during compaction and ejection but also caused compaction inhibition. Transverse rupture strengths were determined on compacts containing various stearate based lubricants and it was found that green strength was reduced by the interposition of a thin lubricant layer within inter~particle contacts. Only materials much finer than the iron powder respectively) were able to form such layers. Investigations were undertaken to determine the effect of the decomposition of these lubricants on the development of mechanical properties in dewaxed or sintered compacts. Physical and chemical influences on tensile strength were observed. Decomposition of lubricants was associated with reductions of strength caused by the physical effects of pressure increases and removal of lubricant from interparticle contacts. There were also chemical effects associated with the influence of gaseous decomposition products and solid residues on sintering mechanisms. Thermogravimetry was used to study the decomposition behaviour of various lubricants as free compounds and within compacts. The influence of process variables such as atmosphere type, flow-rate and compact density were investigated. In a reducing atmosphere the decomposition of these lubricants was characterised by two stages. The first involved the rapid decomposition of the hydrocarbon radical. The second, higher temperature, reactions depended on lubricant type and involved solid residues. The removal of lubricant could also markedly affect dimensional change.

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