LU83594A1 - IMPROVED PROCESS FOR THE PNEUMATIC REFINING OF HEMATITIS OR PHOSPHOROUS CAST IRON TO THE CONVERTER - Google Patents

Description

> 1 · (Resale of the priority of a patent application N filed in Belgium on September 2, 1980 under No. 885.044 i î * C 2074/8009.

BL-3191 / EM / BM

f METALLURGICAL RESEARCH CENTER -CENTRUM V00R RESEARCH IN DE METALLURGIE,

Non-profit association - Vereniging zonder winstoogmerk in BRUXELLES, (Belgium).

| Improved process for pneumatic refining of hematite or phosphorous cast iron with a converter.

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The present invention relates to an improved process for the pneumatic refining of hematite or phosphorous pig iron with a converter.

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j pneumatique The pneumatic refining of cast iron, whether it is hematite v I, jj or phosphorous, has been carried out and is carried out, currently, according to many processes well known in themselves.

In the course of their various developments and improvements, these methods have used an increasingly energetic oxidizing agent, from atmospheric air to commercially pure oxygen. .

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Parrai the processes which were most commonly used or which are now used for hematite cast iron, one can quote in particular r - that where, in a converter with full bottom, one injects the refining gas, generally of pure oxygen, from the top of the converter, using a refining lance. The necessary lime is then introduced through the converter spout, in the form of large chunks (lime in rock), which leads to difficulties in dissolving the lime and consequently, the formation of slag and of obtaining the desired final composition of steel, that according to which the refining is done by injecting pure oxygen through nozzles housed in the bottom of the converter. In this case, the addition of lime is in the form of powder, suspended in the refining gas, however having the drawback of rapid wear of the nozzles and leading to difficulties in ensuring an equal distribution. lime '! between the different nozzles, - that according to which a refining with pure oxygen is carried out, by simultaneous blowing from the top of the converter and by appropriate nozzles (most often with two concentric conduits) housed in the refractory lining of the converter, r · below the upper level of the metal being refined. The lime is introduced in the form of a powder suspended in the oxygen injected through the nozzles. Such a method also has the disadvantage of rapid and variable wear of the nozzles, of an inhomogeneous distribution of the lime in the metal and of a certain difficulty in developing high carbon steels.

Among the processes which have been most commonly used or which are now used for phosphorous smelting, there may be mentioned in particular: * Ϋ • 3 _ ί - that according to which, in a full-bottom converter, one injects from above, using a suitable lance, pure oxygen on the metal bath. The necessary lime is put in the form of powder suspended in the refining gas. This process has the drawback of easily leading to slag overflows, - that according to which pure oxygen is blown from the bottom of the converter, through appropriate nozzles, the lime used being partly in rock, introduced by the converter spout, and partly in powder, introduced in suspension in: the refining gas blown from the bottom of the converter.

• Such a method has the drawback of rapid wear of the nozzles, and leads to difficulties in ensuring an equal distribution of the lime between the different nozzles. The risks of overflowing are however less with this process, - that according to which one blows pure oxygen in the metal bath, both from above and from below, lime being always at l powder state introduced into the bath, through nozzles housed in the refractory lining of the converter, suspended in the oxidizing gas. The disadvantages of this process are the same as those of the previously mentioned process.

The present invention specifically relates to a pneumatic refining process for hematite or phosphorous cast iron similar to those described above and not having the aforementioned * drawbacks.

The process which is the subject of the present invention in which the refining of hematite or phosphorous cast iron is carried out pneumatically by injecting pure oxygen simultaneously from the top of the converter by means of a lance, and by the bottom, through suitable nozzles (for example with two coaxial conduits), housed in the wall of the converter, laterally below the metal level and / or in the bottom of the converter, is essentially characterized in that, a part at the less of the / lime to be introduced into the bath, is from the top of the convert

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4.- (* seur, in the form of powder of suitable particle size, and injected on or in the bath by suspension in the refining gas blown through the lance.

·; Advantageously, most of this lime and even all of it is introduced in this way into the metal bath.

In the case of phosphorous cast iron, any complement j of the lime can be introduced into rock by the nozzle of the converter jig and / or powdered by the nozzles.

I "" ’It has been found that this process provides better distribution of lime in the bath and therefore better homogeneity of the metal. Furthermore, it eliminates, or significantly reduces, the wear on the nozzles, does not cause overflow and • allows the metal to dephosphorize; it facilitates 1 equal initial composition of the cast iron, obtaining higher carbon steel. ·! i: j / i - i! • * i.

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Claims (3)

1. Improved process for the pneumatic refining of hematite or phosphorous cast iron in the converter, in which the refining of the cast iron is carried out pneumatically by injecting pure oxygen simultaneously from the top of the converter using a launched, and from below, through suitable nozzles (for example with two coaxial conduits), housed in the wall of the converter, laterally below the level of the metal * and / or in the bottom of the converter, characterized in that a * at least part of the lime to be introduced into the bath, is by "the top of the converter, in the form of powder of suitable particle size, and injected on or in the bath by suspension. in the refining gas blown in across the spear .. 2. Method according to claim .1, characterized in that most of this lime and even all of it is introduced in this way into the metal bath. 3. Method according to either of claims 1 and 2, characterized in that, in the case of phosphorous cast iron, the possible complement of lime is introduced "in rock by the nozzle of the converter and / or in powder through the nozzles. ^ -----:: *