Centro Sperimentale Metallurgico S.p.a.

Centro Sviluppo Materiali S.p.a.

Pasquale Masucci

Paolo Sommovigo

In the production of stainless steels, it is possible to use foamed slag, with great advantages, by using a metal charge with specific carbon and silicon contents, by insufflating limestone and carbon, by controlling the amount of employed oxygen and by maintaining the basicity index of the slag within specific values.

Process for using foamed slag in stainless steel production

Electrode immersion depth is controlled in an ESR process, in which two electrodes are connected in series to a power source and each of the electrodes has an independent feed mechanism. The assumption is made that the slag used in the ESR process has a composition which does not vary during the process, thus leading to the further assumption that two equal lengths of slag have equal electrical resistance. Hence the slag comprised between the electrode tips and the molten metal bath can be considered as two variable resistances which are equal only when the electrode tips are both at the same distance from the molten metal bath. These two variable resistances are used in an electrical bridge, which can be suitably balanced. Should one electrode be consumed more rapidly than the other, the thickness of the slag, as well as its electrical resistance, between the electrode tip and the molten metal will increase, thus unbalancing the bridge. The amplitude and direction of this unbalance will tell both which electrode is consumed more rapidly and at what rate, thus enabling the operator, or an automatic device, to correct the feed rate of the electrode.

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Rome, Italy

Pasquale Masucci