フェロシリコン中のC及びS定量方法に関して,特に高周波誘導加熱炉燃焼-赤外線吸収法についてその燃焼条件を共同実験によって検討した.Cについては,JIS法による管状電気抵抗加熱炉燃焼-電量法又は導電率法を基準方法として比較検討し,高周波誘導加熱炉の場合は助燃剤としてFeとW又はFeとWとSnを用いた場合良好な結果が得られた.Sについては,還元蒸留メチレンブルー吸光光度法を基準方法として比較検討した結果,助燃剤としてFeとWとSnを用いた場合良好な結果が得られた.更に,その結果から各方法の分析精度及び定量下限を明らかにした.

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For the operational guide of electric furnace for producing silicomanganese, a new simplified mathematical model suitable for online application has been developed on the following procedure.
(1) Equations for the estimation of reaction rates are derived from material balance through the charge conditions and the exhaust gas compositions.
(2) The ratio of transference of MnO, FeO, SiO₂ into slag and the amount of permeation of carbon into metal are formulated as the functions of operational variables.
(3) By using the above-stated formulated equations, the transition of metal formation rate and metal temperature can be estimated.
At EF shop No. 2 in Kashima Works of Chuo Denki Kogyo Co., Ltd., the model is being used for the guidance of the operation and contributes to the reduction of electric power consumption.

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This study was carried out on the relation between the “apparent equilibrium constant” and the composition of slags upon the reaction, 2Mn+SiO₂\ ightleftarrows2MnO+Si, in Fe-Mn metallurgy as follows. H-C-Mn of gradually varied Si contents and sulpherless synthetic Fe-Mn slags of gradually varied basicity were used and kept melting for the required time in a graphite crucible in a Tammann electric furnace and then “apparent equilibrium constant” was calculated from the results of the analysis. (1) MgO played the part of basic components as well as CaO. Therefore, in calculating the basicity of the slags, MgO must be added to CaO by moleexchanging. (2) Al₂O₃ could be regarded the as neutral component in the above conditions. (3) The relation between the “apparent equilibrium constant”, K_Mn-Si^a=(ΣMn)\sqrt[Si]⁄[Mn], and the slags composition was nearly represented by the following equation at 1510°. The concentrations expressed by weight %. logK_Mn-Si^a=-1.257(CaO+1.39MgO)/SiO_2+0.694

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In the present work, various chrome ores and relatively pure chromites separated from them were reduced with powdered graphite over a temperature range of 1050° to 1400°C under a flow of argon.
The results obtained are as follows:
1) Roughly speaking, the reduction process of natural chromite consisted of the following three stages:
2) The reduction products of the 1st stage were metallic iron and cementite, while the chromium-bearing product, (Cr, Fe), C₃, was produced after the beginning of the 2nd stage.
3) Of the constituents of chromite, iron oxide had the strongest influence on its reducibility. At tem peratures below about 1200°C, the porosity of chromite particles was also of great interest, and porous chromite was reduced more easily than compact chromite.
4) At temperatures above 1300°C, a considerable portion of SiO₂ contained in chrome are was reduced.
5) The gangue minerals such as forsterite and enstatite retarded the reduction of chromite at temperatures below 1250°C, but accelerated it at higher temperatures.

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The coal was successfully used as a binder of powdery sample of ferrosilicon for its fluorescent X-ray analysis. By mixing 7% coal and ferrosilicon which were then ground in a vibrating mill for 2 min and mold by press, a bricket specimen with stiff and smooth surface was obtained. This binder was convenient and inexpensive. It showed only slight temporal variation and suitable also for the preparation of reference specimen. Si, Al, Mn, Ca, Ti and Fe in ferrosilicon were accurately determined by using this binder.

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Russian chromite particles reduced to various stages of reduction with graphite were subjected to the analyses by an X-ray diffractometer and an electronprobe microanalyser.
At 1 100°C, the chromite was reduced only to a slight extent. At the temperatures between 1 150° and 1 250°C, metallic beads were formed on the surface of a chromite grain. Their Cr content was relatively low. The grain was divided into the core of almost unreduced chromite and the outer layer depleted in Fe and rich in Al and Mg.
At 1 300°C or above, metallic beads with a higher content of Cr were formed around the grain. In the later stage of reduction, the grain was divided into three zones, i.e., the outer layer mainly consisted of MgAl₂O₄, the inner layer depleted in Fe only, and the core of almost unreduced chromite. Metallic beads were formed in the outer layer and the inner layer separately and a darker doughnut-like zone was observed between them in a coarser grain (above 100μm). A considerably large content of MgO was observed in this zone. Metallic phase formed in the inner layer was vein-like and rich in Fe.
At 1 250°C or above, the transfer of Si from gangue into chromite grains was observed, which was considered to be the main reason of the acceleration of the reduction rate of chromite ore with SiO₂.

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鉄鋼および試料を燃焼ボートに採り,1450℃の温度で酸素ガスを通じながら燃焼させてイオウを亜硫酸ガスとし,0.2M Na₂HgCl₄溶液に吸収させたのち,ホルマリンおよびパラローザニリンを加えて発色させ,20分間放置後,550mμの波長における吸光度を測定してイオウを定量した.また,助燃剤として五酸化バナジウムの使用を試み,酸化物の飛散をほぼ完全に防止し,満足できる結果が得られた.
本法の分子吸光係数は44,000で,0～35μg/100mlの範囲で直線関係が得られた.再現性については,イオウ含有量0.015%の炭素鋼の場合は5.4%,イオウ含有量0,010%のフェロタングステンの時は7.0%の相対標準偏差であった.
これらの結果より,0.004～0.070%程度のイオウを精度よく,迅速に定量できた.

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蛍光X線分析法による溶液試料の測定方法として点滴濾紙法がある.従来の方法は乾燥方法や滴下する液量にかなりの制約があった.新しく提案する濾紙を支持担体に固定する方法では,乾燥時の熱によるゆがみあるいは劣化による支持部の切断等の問題がなくなった.また,軽元素に対しては濾紙の厚さを薄くすることにより,濾紙による蛍光X線の吸収を抑制できた.重元素に対しては,厚さと面積を大きくすることにより,滴下量を拡大することができた.以上のことから,蛍光X線強度が増大し,感度の向上が得られた.

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Phosphorous in ferrochromium was determined without separation of chromium by the molybdenum blue method. Following the preceding report on effects of reagents on the color development, effects of chromium and a few of salts or acids on the color development were further investigated. Effects of co-existing elements, salts and acids, were mainly to retard the rate of color development. Above all, chromium (III) had a remarkable effect. As a result of experiments on the color development in detail, it was found that the effect of chromium (III) could be eliminated when the concentration of reagents was increased and the digestion time was prolonged. In like manner, the effect of acids could also be eliminated. Chromium (III) showed almost no absorption at the wavelength of over 750 mμ.
In this experiment, a reagent mixture solution of 12 mL of 2% ammonium molybdate, 13 mL of 10N sulfuric acid and 5 mL of o.15% hydrazine sulfate was used, and digested at the total volume of about 90 mL for 30 minutes. Chromium (III), amounting up to 150 mg, had no effect in this condition.
This wethod was expedient and its accuracy was equivalent to or higher than that when chromium was separated.

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  The process of Sr-decrease in molten Al-Si-Mg alloy was studied by emission spectrochemical analysis of Sr in molten metal, X-ray fluorescence analysis of dross formed at degassing process and SEM observation of surface film on molten metal. It was decided that there are three processes of Sr-decrease ; (1) Mg and Sr, melted uniformly in molten metal, is oxidized simultaneusly and forms a surface film. (2) Sr combined with hydrogen gas and oxide in molten metal comes up to the surface and separates from the molten metal. (3) Ar-degassing treatment promotes the second process. Ar-gas also breaks the surface film and more promotes oxidation Sr.

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