JPS6070118A - Method and apparatus for manufacturing high purity and small gas content steel in steel plant or iron cast plant - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides FiIf processing of molten steel in a ladle with an inert gas,
The present invention relates to a method and apparatus for producing high purity, low gas content steel for special specifications, in which the processing steps of refining and deoxidation are carried out in a converter.

BACKGROUND OF THE INVENTION Several methods are already known for producing steels of high purity and low gas content.

The best known of these is melting in an electric arc furnace or melting in an electric arc furnace followed by refining in a converter using mixed gases or in vacuum.

The production of special steels, which is carried out exclusively in electric arc furnaces, is very expensive in terms of energy technology and there are problems with regard to the purity that must be set.

The production of steel by arc furnace followed by refining using gas mixtures in known converter furnaces is such that these converters, which were originally designed only for the production of chrome steels, are capable of producing steels of the above-mentioned quality. It has the disadvantage of having a smaller specific reaction volume than is required for production. A prerequisite for the necessary high refining and heating rates is a large specific reaction volume with a high specific oxygen supply.

Furthermore, during the deoxidation step, reoxidation of the molten metal by air entering the reaction space cannot be avoided.

Furthermore, during the tapping of the reduced steel, strong contact with atmospheric oxygen takes place, resulting in the formation of harmful oxidized impurities,
Generates waste in the product.

The production of said steel with subsequent refining in a vacuum converter becomes more complex and expensive due to equipment and operating costs.

The methods described above are also difficult to implement and require a high degree of experience and the use of specialized personnel.

Furthermore, it is known that during the production of these coppers it is possible to carry out the final treatment in a ladle that is passed through an inert gas. However, in this case too, if it is not possible to reproducibly set the predetermined initial values of the arc furnace or the hitherto known converter, the precise setting of the desired values with respect to alloying composition, temperature, oxygen and hydrogen values and purity is impossible. impossible or extremely difficult.

Furthermore, it is particularly disadvantageous in the three aforementioned methods that the desired metallurgical values are not established with sufficient certainty, so that it is no longer possible to avoid monthly defects, which are no longer acceptable in heavily loaded equipment sections, for example in nuclear power plants.

OBJECTS OF THE INVENTION The object of the invention is therefore to provide a well-reproducible and stable quality of the steel, which no longer has the above-mentioned disadvantages, and with increased productivity and reduced waste risks and a better control of the operation. The object of the present invention is to provide a method and an apparatus for manufacturing steel, which in particular makes it possible to guarantee the quality of steel.

Furthermore, the apparatus for carrying out the method according to the invention can be constructed relatively simply and can be operated in an energy-friendly manner, making it possible to dispense with the use of vacuum and high operating costs.

Means for Achieving the Object In order to solve this problem, in accordance with the invention, in the first mentioned method, an inert gas-air-oxygen gas is added in a converter together with the desired alloying components after melting and before ladle treatment. 1 depending on the mixture
Refining is carried out in one or more stages, and the individual processing steps, ie refining, deoxidation and purification, are divided so that each stage can be carried out optimally without disturbing the overall process relationship. These stages include heating followed by a fast deoxidation stage;
After tapping, a purified gas pouring step using an inert gas is carried out in the ladle.

The collected slag may be fed onto the melt during ladle processing time. This is followed by a purified gas flushing step, which avoids the formation of especially harmful coarse inclusions (9).

In this connection, in particular argon can be used as inert gas.

Furthermore, during the deoxidation stage in the converter, the converter opening area is reduced and/or a deoxidizer is supplied to avoid oxidation of the steel during tapping from the converter, making the converter atmosphere oxygen-free. can be kept.

The equipment for carrying out the above-mentioned method includes the presence of a converter for refining and deoxidizing the steel in several stages, and the use of air - inert gas -
Treatment with mixtures of oxygen and only inert gases is possible in sequence with widely varying gas quantities.

It is advantageous if the converter has a device which makes it possible to reduce the converter opening intermittently.

Furthermore, it is advantageous if the converter has a gas quantity regulating device and an inlet opening that make it possible to continuously change the different gases to be injected. It is advantageous to individually control the flow into the blow openings.

Further advantageous developments of the method and the device according to the invention are apparent from the exemplary embodiment section (10) of the patent claims.

In summary, the invention enables the production of particularly high-grade steels while avoiding the use of vacuum during the setting of copper to the desired metallurgical values with little equipment outlay and with qualitatively reproducible and stable Enabling control.

The present invention has the following advantages over hitherto known devices and methods. i.e. easy possibility of chemical analysis of the steel and precise setting of temperature, easy setting of the final sulfur value according to requirements, good mechanical values in the final product, increased production capacity, easy control possibility. reliable reproducibility of results, energy-saving and environmentally friendly operation, economical use of raw materials, low investment costs in setting suitable quality targets.

Example Embodiments of the present invention will be further explained with reference to the drawings.

According to FIG. 1, in stage I the steel is melted, which can take place in a cupola, an induction or electric arc furnace, or in a crucible heated by a lance.

(11) In stage TI the molten steel is tapped and added with the desired alloying additives and such additives as will enable the required temperature rise in the refining process through stages JT and TTT.

In stages TI and III, the converter treatment is carried out with flux and additive charges, oxygen, nitrogen, air or argon or mixtures of these gases.

After tapping the molten metal into the ladle, the purified gas is poured into the ladle using the stage TV, and then in the stage (2), sea cucumber making, mold casting or continuous casting can be carried out.

In detail, after tapping from the melter according to step (1), addition of alloying elements and flux elements takes place, and then the two-phase treatment described above takes place in a converter. Known inert gas
The blowing of air-oxygen compounds results in rapid and intense refining with a significant temperature increase from about 1500°C to over 1700°C. This refinement can be aided by a lance. Then a relatively small temperature drop (
12) A rapid deoxidation step is carried out, in which the desired settings of the final analysis are already well established and the oxides formed during the refining are reduced to a large extent. Tapping takes place after a rapid deoxidation stage with high gas flow rates. A purified gas pouring step with a very low gas flow rate, for example 01 to 0.05 m@3 /l, then takes place in the ladle.

What is required in this regard is that the mixing and monitoring mechanisms for the introduction of the necessary gases into the converter have a suitable design, and that the blow openings at or near the bottom of the converter have a stage with a small gas flow rate. It is also constructed so that it is not blocked by incoming steel. It is advantageous to narrow the converter opening /IX during the deoxidation stage. The device for reducing the size of the converter opening can be configured such that the opening remains in the converter when the molten metal is tapped.

In another step of the process, the molten metal is discharged over the rim of the converter, and the slag is flushed with it into the ladle, where it forms part of the collected slag.

An inert gas atmosphere is maintained in the converter (13) during flushing, using a deoxidizer or an inert gas shield to avoid reoxidation of the effluent steel by atmospheric oxygen.

This ladle treatment precisely sets the desired metallurgical values for chemical analysis, salinity and purity, resulting in a molten metal that later avoids coarse inclusions.

A steel with good properties is thus produced.

The steel is then cast in stage V with protected melt flow.

When carrying out this method, care must be taken that all alloys used are dry and all additives are added to the melt early to ensure good gas permeation as well. be.

All slag-forming materials are pre-loaded into the converter;
The charge should be able to be loaded without slag. In the converter, at least 0.5% of the carbon is removed by smelting.

The supply of operating gas is adjusted to 0.5-2. It must be adjustable within the range of ONm3/l,/min.

(14) At least 4 to 6 Nm”Ar during the processing time in the converter
Gas is poured in at a rate of /l, and the time from completion of the molten metal to tapping is set to be at most 5 to 10ml.

Furthermore, it is advantageous to line the tapping ladle with a basic or neutral lining. It is necessary to preheat this ladle well and equip it with one or more bottom pouring bricks.

A particular advantage of the method and device according to the invention is that it can be used not only for the production of good steel in industrial areas, but also effectively in less industrialized areas due to its simplicity and stable implementation of the process. It is.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the individual stages of steel production according to the invention;
FIG. 2 is a diagram showing the variation of temperature in the individual stages according to FIG. ■~V...Continued from page 1 of Stage Luk Akchengesellschaft LA: DE) [Co.] P3347718.3 Oberno 1 Uzen 11. Prussenstosea

Claims (1)

[Claims] 1. In a method of manufacturing steel by flowing an inert gas into molten steel in a ladle, inert gas-air-oxygen is mixed in a converter together with desired alloy components after melting and before ladle treatment. Refining is carried out in one or more stages with a mixture of A method for producing high-purity steel with low gas content in steel mills and steel foundries. 2. A method according to claim 1, characterized in that the collected slag containing the deoxidizing substance is fed onto the molten metal in the ladle. 3. The method according to claim 1 or 2, characterized in that purified gas is poured into the molten metal within the ladle processing time. 4. The method according to claim 1, wherein after refining in the converter, a deoxidizing step is carried out while flowing an inert gas strongly. 5. Process according to claim 1, characterized in that the converter is discharged over the brim and the slag is poured off with it into the ladle. 6. The method according to any one of claims 1 to 5, characterized in that the oxygen content of the steel is set to 20 ppm or less for chromium-containing steel, and to] Oppm or less for metal alloy mesh. Method. 7. The method according to claim 1 or 5, characterized in that an inert gas atmosphere is maintained during tapping of the converter. 8. The amount of inert gas or air-oxygen or inert gas-oxygen passed during the heating stage and during the deoxidation stage is several times the amount of inert gas passed during the purified gas pouring stage in the ladle. (2) The method according to claim 4, characterized in that the size is increased by at least 10 to 22 times. 9. Claim 1 or 4 or 8, characterized in that the converter opening area is reduced during the deoxidation stage.
The method described in section. 10. The method according to claim 1 or 2 or 4 or 8, characterized in that a deoxidizing agent is supplied to the steel to be used during tapping. 11. Process according to claim 1, characterized in that the effluent steel is protected against oxidation by an inert gas shield. 12 At the end of the whole process, with 10 parts of slag, the following composition: 1-2 parts of Al203 1-3 parts of 3102 2-5 parts of Ca0 1-2 parts of Mg0 1 part should be set to other metal oxides A method according to claim 1 or 2 or 5, characterized in that: 13 During the refining period the carbon content of the steel is reduced to at least 0.5
Claim 1 characterized in that the reduction is made by %.
The method described in section. 14. Process according to claim 13, characterized in that the refining period is shortened by an additional double blow or blow of oxygen with a lance. 15. Process according to claim 13 or 14, characterized in that the oxide-containing solid material is added by means of a carrier gas through a lance. 16 The specific reaction volume in the converter is 0 per 1 t of production capacity.
．． 45 to 0.80. 17 Refining in one or more stages with an inert gas-air-oxygen mixture in a converter prior to molten diameter ladle treatment with the desired alloying components, each stage being carried out without disturbing the overall process relationship. In order to optimally carry out the process, converters are present for refining the steel in several stages, in a device that separates the individual processing stages, namely refining, deoxidizing and This method enables treatment with only inert gases and inert gases at successively significantly different amounts of gas, and is characterized in that a ladle is provided after the converter for pouring purified gas into the steel. Equipment for manufacturing steel with low gas content. 18. Apparatus according to claim 7, characterized in that the converter opening has a device for making it possible intermittently to reduce the converter opening. 19. Apparatus according to claim 17, characterized in that the converter has a gas quantity adjustment device and a blowing opening, which make it possible to change the different gases to be blown into the converter. 20. Device according to claim 19, characterized in that an inlet opening with an individual control device is provided. 2. Claim 17, characterized in that the finished ladle for the molten metal is lined with a basic or neutral #fire material, so that no oxygen is supplied to the molten metal from the ladle lining.
Equipment described in Section. 22. The container N according to claim 21, wherein the completed molten metal tapping ladle is lined with dolomite.