The effects of CaO, Al₂O₃ and MgO, all as the foreign oxide, on the rate limiting step of the reduction of pellets from wustite to metallic iron and on the values of rate parameters are studied.
It is confirmed that the reduction behavior of those pellets may be represented either by the unreacted core model or by the uniform reaction model, depending on which kinds of the foreign oxide and the iron oxide are present at the start. The mixed rate control equation of mass transfer in the gas phase, intraparticle gas diffusion, and chemical reaction may be applied to any iron oxides that contain CaO and to hematite and magnetite both containing Al₂O₃. On the other hand, the reduction rates of the pure iron oxides, wustite containing Al₂O₃ and any iron oxides containing MgO are controlled by the oxygen diffusion in the metallic iron shell.
These results agree with the conclusion of the present authors' previous studies, namely, when a complex oxide that consists of an iron oxide and any one of those foreign oxides precipitates in wustite during reduction, wustite grains are reduced nontopochemically while pellets are reduced topochemically.

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The kinetics of reduction of molten iron oxide with CO gas at high temperatures of 1450 and 1600°C were investigated. In order to reduce the influence of mass transfer rate on overall reaction rate of reduction, fine powders of iron oxide were used as specimen and were reduced in a transport reactor. After the specimens of fine powder of reagent grade were melted during falling down in reaction zone, liquid oxide drops thus formed were reduced with CO gas. Mean diameter of liquid particles was 25μm.
The oxide particles were melted and became spherical, and the reduced iron was surrounded by liquid iron oxide. It is assumed that liquid iron oxide always exists on whole spherical surface and the nucleation, growth and cohesion of iron in liquid drop did not influence the overall reaction.
The results were analyzed by considering only the mass transfer in a gas film and the chemical reaction at the gas liquid interface.
The value of mass transfer coefficient in gas film k_g was estimated by using the Ranz-Marshall equation kg_d/D=2.0+0.6Re^1/2Sc^1/3. Considering the shrinkage of particles by production of metallic iron, the values of rate constant of chemical reaction k_c were obtained as 19.4cm/sec at 1600°C and 9.3cm/sec at 1450°C.

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Cryogenic nickel steels show larger elongation as temperature decreases. The presence of retained austenite (γ_R) is suspected to be one of the causes of this behavior. In order to clarify the effect of this phase on the deformation behavior, 5.5 Ni, 9 Ni and 11 Ni steels were studied.
The increase in elongation was mainly due to the increase in uniform elongation and independent of the existence of γ_R. Although γ_R of these steels were considerably stable against sub-zero treatments, they were easily transformed to martensite by plastic deformation at -196°C and to the lesser extent even at room temperature. The mechanical stability of γ_R was quantitatively determined using the parameter, s=-(1/V_γ) (Dv_γ/dε), where V_γ is volume fraction of γ_R and ε is true strain. It is concluded that TRIP effect of γ_R, if any, can hardly contribute to the increase in elongation of these steels. The temperature dependence of thermal activation parameter measured in the 11 Ni steel indicates that the plastic deformation mechanism in the vicinity of room temperature is maintained even at very low temperatures. This fact may relate to the excellent low temperature ductility of the cryogenic nickel steels.

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Experiments have been made to study the vanadium distribution between the CaO-MgO-FeO_x-SiO₂ slag and liquid iron equilibrated in a magnesia crucible in the temperature range from 1550°C to 1650°C. The vanadium distribution ratios (V)/[V] were about an order of magnitude higher and their dependence of slag compositions and temperature was found to be smaller compared with the phosphorus distribution ratios (P)/[P]. A linear relationship was observed between logarithm of (V)/ {[V][O]ⁿ} (n=2 or 2.5) and CaO/SiO₂ ratio. The V⁵⁺/(V⁴⁺+ V⁵⁺) ratio increases with increasing CaO/SiO₂ ratio, while V³⁺, V⁴⁺ ions were observed in the slag compositions of CaO/SiO₂<1. Phosphorus, silicon, and vanadium distribution ratios between slag and carbon saturated iron melt was obtained at 1350°C by use of the distribution ratios between slag and liquid iron at a high temperature and interaction parameters. The order of oxidation of silicon, phosphorus, vanadium, manganese and chromium in pig iron is discussed on the basis of the equilibrium partitions and capacity concept.

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In order to find its feasibility as blast furnace coke feedstock, non-metallurgical coal was compared with metallurgical coal in terms of reactivity and degradation during CO₂ gasification reaction, with emphasis on the difference between the pore structure of coke and that of char. The following results were obtained:
(1) The higher reactivity of non-metallurgical coal char is due to the fact that their coal rank is lower.
(2) Though the pore structure of metallurgical coke is composed mainly of macropores, pore walls of char are either abundant in micropores when the rank is low, or practically nil in any size when the rank is relatively high.
(3) Open macropores characterize the pore structure of coke, while char has a considerable number of closed pores.
(4) The deterioration of the structural strength of coke becomes greater than that of char as gasification reaction proceeds.

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Fluorescent X-ray analysis of iron contents in iron ores by glass bead technique has been theoretically studied. Calculation has been made on FeK_α fluorescent X-ray intensity in Fe-O binary sample and in Fe-O-impurity ternary sample in various fusion procedures by means of theoretical formulas for fluorescent X-ray intensity. The results are as follows:
(1) In the comparison of characteristics of various fusion procedures, the intensity decreases, the derivative of calibration curve increases and matrix effect decreases with X-ray absorption of glass bead. For example, in the procedure in which lanthanum oxide is used as reagent, matrix effect is low and lanthanum oxide is useful as heavy absorber, while vanadium oxide has a little effect as heavy absorber and matrix effect is not low.
(2) In the procedure in which anhydrous sodium tetraborate is used as flux, calibration curve for Fe-O binary system sample is made, and FeK_α intensity is calculated for Fe-O-impurity ternary system samples when impurity is substituted with oxygen in Fe-O binary system sample. Theoretical correction factors are derived from the change of FeK_α intensity. It is shown in experiments that these correction factors have an effect on analysis of iron content.

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The deep drawability and the recrystallization texture of rephosphorized Al-killed high strength steels (P: -0.07%) were studied as compared with those of a conventional Al-killed steel (P: 0.016%).
A rephosphorized Al-killed steel shows the peak r-value at a certain heating rate in annealing as well as a conventional Al-killed steel. However, phosphorus slightly weakens the retardation effect of AlN on recrystallization, which results in a lower r-value and a lower grain elongation ratio. The preferred orientation of a rephosphorized Al-killed steel is {111} <112> though that of a conventional Al-killed steel is {111} <110>.
These results are discussed by taking into account the interaction between phosphorus and AIN precipitation behavior.

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Wakayama Steel Works, Sumitomo Metal Industries, Ltd., developed the “On-line Maintenance Information Control System (MICS)” in Oct., 1980. The real time information of maintenance work planning, plant histories, spare parts inventories, etc., available from this computer system made more effective maintenance possible.
This paper presented explains how the system was developed and the results of its application.

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