Chemistry: electrical and wave energy – Processes and products – Processes of treating materials by wave energy
Patent
1991-06-17
1994-08-30
Tung, T.
Chemistry: electrical and wave energy
Processes and products
Processes of treating materials by wave energy
204422, G01N 27417
Patent
active
053424891
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method of measuring with high accuracy the oxygen activity of slag in molten iron or molten steel which is produced in the steel making process, a measuring apparatus used for the method and a disposable crucible used for the apparatus.
BACKGROUND ART
A method is conventionally known of measuring the oxygen activity of the slag in molten iron or molten steel by winding in a close contact state a platinum contact electrode around the outer surface of a solid electrolyte in the form of a tube having one end closed or by coating the outer surface thereof with a platinum contact electrode to prepare an oxygen concentration cell, embedding the oxygen concentration cell in the end of the probe, and disposing a probe directly in a molten slag layer which is existent in the upper layer of the molten steel in a converter or a ladle during operation.
Since the surface of the slag flows violently, however, it is difficult to exactly locate the oxygen concentration cell, which serves as a detecting portion, in the slag, so that the times at which measurement succeeds is low. Since the detecting portion is exposed to a high temperature for a long time, a firm heat-resistant material is necessary, therefore the probe becomes thick and heavy, and thus difficult to handle. In addition, it is necessary to bring the platinum into contact with the surface of the solid electrolyte in order to produce the oxygen concentration cell in the above-described form. Since the solid electrolyte is densified by the heat of the slag during operations, it is difficult to constantly maintain the contact state and thus a defective contact between the solid electrolyte and the contact electrode is produced, which results in the production of an error in measurement. Furthermore, although it is necessary to stop the progress of the steelmaking process for the measurement, it is actually impossible to stop the steelmaking process for a long time. It is therefore impossible to use a probe-type oxygen measuring apparatus in an industrial furnace.
Accordingly, it is an object of the present invention to solve these problems in the prior art and to provide a method of measuring the oxygen activity of slag which is capable of measuring the oxygen activity of a slag with high accuracy and to provide an oxygen activity measuring apparatus which is used for the method and which is very easy to handle.
DISCLOSURE OF THE INVENTION
The present inventor thought of measuring the oxygen activity of a slag not directly but indirectly, by selecting a specific metal between which metal and a slag an oxygen equilibrium is established when it comes into contact with the slag, accommodating the metal and the slag in the same container and measuring the oxygen activity of the metal. By materializing this idea, the necessity of the contact electrode being in close contact with the surface of the solid electrolyte is obviated and the problem caused by the defective contact between the solid electrolyte and the contact electrode is solved.
In a first aspect of the present invention, there is provided a method of measuring the oxygen activity in a slag comprising the steps of: dissolving a specific metal which is hardly alloyed with iron and hardly produces an oxide in an inert atmosphere and which has a larger specific gravity than the slag in a steel crucible; immersing a solid electrolyte of a tube type having one end closed with a reference electrode provided therewithin in the specific metal and bringing a contact electrode into contact with the specific metal so as to form an electric closed circuit between the reference electrode and the contact electrode through the specific metal; and measuring the oxygen activity of the specific metal.
In a second aspect of the present invention, the above-described measuring method is materialized and there is provided an apparatus for measuring the oxygen activity in a slag comprising: a steel crucible disposed in a smelting furnace which is filled with an inert ga
REFERENCES:
patent: 3281137 (1966-10-01), Alper et al.
patent: 3616407 (1971-10-01), Engell et al.
patent: 3652427 (1972-03-01), Flood et al.
patent: 3661725 (1972-05-01), Ulrich et al.
patent: 3794569 (1974-02-01), Kawai et al.
patent: 4639304 (1987-01-01), Bader et al.
patent: 5096165 (1992-03-01), Auer et al.
Fujiwara Ryuji
Iwase Masanori
Mochizuki Ryo
Tung T.
Yamari Electronite Kabushikigaisha
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