Through the statement of the turbulent Navier-Stokes equations and a coalescence model of Saffman and Turner a mathematical model has been proposed to describe deoxidation kinetics in an R-H vacuum degassing unit. An important feature of the work was that a population balance model was used and that an allowance was made for the spatial non-uniformity of the coalescence rate.
It was found that the R-H vacuum degasser is an excellent mixer with virtually all the material contained in the ladle being involved in the overall circulation. The maximum turbulence energy dissipation occurs in the vicinity of the “down-leg” but the calculations have shown a remarkable spatial uniformity of the inclusion particles, notwithstanding the fact that the rate of coalescence was markedly non-uniform.
It is thought that the population balance approach outlined in the paper could be applied to a range of systems where the principal mechanism of deoxidation is the coalescence of the inclusion particles.

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The coking is not a single process, but consists of two mechanisms, that is, a bonding of coal particles and a generation of coke strength. From this point of view, both processes have been investigated and the following model is proposed.
(1) A bonding of coal particles, which can be considered as foamable particles, is determined by a mechanism that the voids between particles are filled up by the dilatation of coal. An insufficient bonding between particles yields a structural defect, and is a primary factor in lowering coke strength.
(2) The generation of coke strength determines both the porosity and inherent strength. Thermally decomposed gas and melting materials during the carbonization process influence the porosity. As for inherent strength, it is clear that influences of a coalification rank and carbonization temperature are significant.
Based on these results, a concept of the coking mechanism across the oven width, which is the basis of the reaction in the coke oven, has been considered.

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Estimation of coke strength which indicates the quality of coke and/or heat transfer simulation in a coke oven have been studied and analyzed independently. Whilst either constitutes an integral part of another and can not be an independent subject each other; this is mainly attributable to the lack of an acceptable theoretical construction by which both subjects can be linked up.
The authors have worked out a carbonization model which enables us to estimate the carbonizing condition in a coke oven simultaneously through either aspect of coke quality and heat transfer, based upon the concept of coking mechanism previously reported.1)
The model is particularly characterized by the calculation of density variation in the coal zone and coke zone across the oven width during carbonization and a utilization of the resulted value as basic physical value to determine coke strength and heating pattern.
Also it is characterized by an introduction of the filling ratio of void's volume (F_V) which has already been explained in the previous papers1) into coke strength calculation by accounting the effect of structural defect which may be caused by an incomplete bonding of coal particles during softening and melting.
The model has been tested and identified by both laboratory-scale and actual large-scale coke ovens, and its validity is confirmed.

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The rate of reduction of hematite and magnetite pellets containing coal char in a nitrogen atmosphere and at the temperatures between 800°C and 1200°C was investigated. The reduction rate was found to increase with increasing temperatures, and increasing calcium oxide content of the pellets. The reduction was not stepwise. That is, iron, hematite, magnetite and wustite were detected by X-ray analysis as coexisting phases during early stages of the reduction process. Large temperature differences were found between the core and surface of the pellets, indicating that the reduction process occurred under non-isothermal conditions.
Calculated values for the apparent activation energy ranged between 38kcal/mol to 51kcal/mol. These values are lower than those reported by previous workers, but still within the accepted range for chemically controlled processes. The rate of the carbon gasification reaction and the rate of heat transfer from the furnace wall to the reacting pellet were found to exert the strongest influence on the overall rate of the process. Considering the observed non-isothermal conditions, the highly endotermic nature of the carbon gasification reaction and the large increase in the reduction rate with increasing temperature, it appeared that the overall process was heat transfer controlled.

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The structural changes that occurred during the reduction of hematite and magnetite pellets containing coal char, in the temperature range between 900°C and 1200°C, were studied.
The behavior of the pellets was complex. Significant temperature gradients within the pellet were attained during the process, and the reduction was accompanied by catastrophic swelling of the pellets between 900°C and 1000°C, while shrinkage was observed at 1100 and 1200°C. Observed microstructural features such as intragranular porosity and cracking of oxide grains resulted from severe lattice disturbances occurring upon transformation of hematite to magnetite.
The catastrophic swelling observed for hematite and magnetite pellets 900 and 1000°C was due to the filamentary or whisker growth of iron outward from the wustite surfaces. The whisker formation appears to be due to a changing reducing potential of the gas phase within the pellet coupled with the presence of calcium oxide on the wustite surface. The shrinkage reported at 1100 and 1200°C is accounted for in terms of sintering of iron filaments.
The pellets strength was found to decrease between 900°C and 1000°C, and increased at higher temperatures. The weakness at low temperatures was due to the absence of bonding between iron filaments or whiskers. The high strength obtained at higher temperatures (1100 and 1200°C) was produced by sintering of iron filaments.

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Mechanical properties have been studied through the changes of Al and N contents in Mn-Mo, Mn-Mo-Ni and Mn-Mo-Ni-Cr steels with regard to solute interactions between alloying elements by means of Charpy V-notch impact tests, tensile tests and microscopical observations.
The results show that the low-temperature toughness is anomalously deteriorated in Mn-Mo and Mn-Mo-Ni steels but indistinctly related in Mn-Mo-Ni-Cr steel by an increase of excess Al. It is also shown that the tensile strength is remarkably increased, slightly increased and not increased at all by an increase of excess Al in Mn-Mo, Mn-Mo-Ni and Mn-Mo-Ni-Cr steels, respectively.

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An application of bottom blown converter (Q-BOP) has been devised to dephosphorize hot metal from [%P]_i=0.140 to [%P]_f=0.010 and desulfurize from [%S]_i=0.020 to [%S]_i=0.010 by injecting with O₂ gas a lime fluorspar mixture of a low 23kg/t within only 2-4min. Experiments have been made to determine the contributions to the dephosphorization of permanent reactor reaction by top slag and of transitory reaction by lime powders injected with O₂ gas from bottom tuyeres and ascending in the bath.
The ratio of dephosphorization, 100 ([%P] _i-[%P]_f)/[%P]_i, is reached 90-95% when fluorspar is added either to injected lime or to resulting top slag, whereas it decreased to 50-70% without the flourspar addition. Detailed analysis has shown that 50-70% of the above ratio of dephosphorization is shared by the transitory reaction, the rest of 0% (without fluorspar) to 25-40% (with fluorspar) by the permanent reactor reaction. Slag particles ascending in the bath have been sampled and found to contain 10-30% P₂O₅, confirming the considerable contribution of the transitory reaction.
With the aid of additional laboratory experiments, the following sequence is found operative for the dephosphorization: Lime particle injected with O₂ gas is transformed to liquid calcium ferrite. During ascending in the bath, calcium ferrite oxidizes [P] to P₂O₅, itself being reduced to CaO which combines with P₂O₅ to form 3CaO•P₂O₅ particles. The 3CaO• P₂O₅ particles ascend to be finaly assimilated in top slag to complete the sequence of dephosphorization.

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The injection technique of a jet of gas-solid mixture is used in Mitsubishi Continuous Copper Smelting Process. In order to design the furnace with minimum hearth wear, it is important to know the behavior of a jet of gas-solid mixture into molten bath. But the direct measurement can hardly be made in an industrial plant.
Therefore, the characteristics of a jet of gas-solid mixture were examined in detail using a cold model, and an equation which is able to estimate the penetration depth of solid was derived on the basis of the results obtained. The reliability of this equation was confirmed by laboratory scale hot model experiments.

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In order to study the formation processes of deoxidation products with manganese during the solidification of iron, inclusions in iron ingots, which were deoxidized with 2% manganese or with 0.2% silicon-2% manganese in an alumina crucible and solidified unidirectionally, were investigated. Almost all the deoxidation products in all the ingots deoxidized with both kinds of deoxidizers, were of nearly spherical shape, and usually contained aluminum and silicon besides manganese, oxygen and sulfur. The oxygen content of the ingot did not vary significantly with the kind of the above two deoxidizers. From such experimental results and the estimation of the supersaturation for the formation of some kinds of deoxidation products, it was considered that the deoxidation products with manganese during the solidification of iron in the alumina crucible had nucleated as MnO•Al₂O₃(s) and grown in liquid state, reacting with Mn, Si, S and O.

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The slag/metal sulphur equilibrium data at 1550°C using lime/alumina slaps containing MgO and small amounts of FeO have been used to assess the free energy of formation of hercynite. Thus, for the reaction: 0.053Fe(l)+Fe_0.947O(l)+Al₂O₃(s) =FeO•Al₂O₃(s) the standard free energy change at 1550°C has been calculated as -7644cal. This value is compared with the experimental data available in the literature.

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An X-ray diffraction method has been developed for quantitative determination of retained austenite in the production line of cold-rolled type SUS 301 metastable austenitic stainless steel sheets. A new unit of diffractometer designed for application in the mill is equipped with an X-ray source of Cr Kα and three separate scintillation detectors and is provided with mechanisms of lateral movement along the transverse direction of strip and rotation around an axis vertical to the strip surface. Intensities of {211} martensite reflection, {110} austenite reflection, and background are measured separately by the three detectors.
Measurements were carried out by scanning of a coil, cold rolled in a reversing mill, during uncoiling operation in a slitting line. Diffraction intensities of austenite phase were weaker in the top and tail ends than in the middle part of the coil. Variation of the diffraction intensities throughout the whole coil length is well correlated with a conceptional distribution of retained austenite which can be deduced from the nickel equivalent and rolling temperature of the tested material. This findings suggest applicability of the present method in the production line, even though the effect of textures is not corrected.
The new X-ray diffractometer unit is proved to be successfully employed in the production mill as a practical means for prediction of inhomogeneity of material properties in the stainless steel strip for use of springs by monitoring the relative amount of austenite and martensite.

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