The direct method of producing iron and steel was introduced, in which the iron ores, especially powdered hematite or magnetite mixed with carbon, were reduced in a long, shallow electric furnace by means of low or high frequency alternate current at high voltage.
Thiss method has been already known as "KOSYUHA DENGEKI Method" and is supposed to the superior to the other kinds of smeltings in the following points:
1. The iron ore charged in the furnace was reduced in a short interval of about 8-15min., supplying high voltage source to the ends of the furnace, and therefore the impurities included in the steel thus made is perhaps very little.
2. The powdered ores, especially powdered magnetite are more suitable for this method.
3. The reduced aggromelates are taken off from the furnace as soon as the reduction is over, and the other unreduced mixture lies still in the furnace which awaits for the next similar process. Thus the mixture protect the fumace from the thermal corrosion.
In the present paper the theoretical investigation of the aforementioned method was first reported from the aspect of chemical metallurgy.
As any other basic oxides were not added, the reaction was usually operated in the presence of an acidic slag (MnO-SiO-FeO system) and therefore phosphorous and sulphur contents of the raw iron were rather high (0·1-0·37% each).
For the purpose of slag formation, other basic oxides as CaO, MnO were added, and (KMn), and reaction temperature were calculated according to the Körber and Olsen's formula of acidic slag.
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