FI81383B - FOERFARANDE FOER BEHANDLING AV SMAELT METALL OCH ANORDNING FOER UTFOERANDE AV FOERFARANDET. - Google Patents

Description

i 1 81383

A method of treating molten metal and an apparatus for performing the method

The present invention relates to the field of metallurgy 5 and to the smelting of metal in a foundry, and more particularly to the treatment of molten metal and to an apparatus for carrying it out.

Today, steelmaking is evolving towards increasing the capacity of smelters, increasing their specific yield and expanding the quality of quality and high-grade steels for various applications.

Melt refining and finishing processes in large high-yield steel smelters, apart from their operating characteristics, 15 are quite difficult and involve a substantial increase in heating time and deterioration of techno-economic indices. Therefore, technical refining operations and treatment of steels (decarbonisation, degassing, desulphurisation, deoxygenation, leaching, etc.) are performed elsewhere than in smelting-20 equipment, i.e., equipment best suited for these purposes.

Modern methods of metal treatment outside the furnace involve the use of vacuum, inert and active gases, highly reactive deoxygenation powders, and modifiers, and also require vigorous mixing and heating of the reactive phases. In relation to the rate and completeness of the reaction and the degree of purification of the metal from harmful impurities, these methods have significant advantages over the peculiarities of their implementation in smelters.

The widespread implementation of off-kiln steel processing is inspired by the continuous casting process of steel, which requires stricter requirements for metal quality (amount of sulfur, gases, non-metallic impurities, uniformity of temperature and composition).

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The treatment of steels outside the furnace is excellent in solving problems of steelmaking, such as the removal of hydrogen from the steel to a level without flaking, the controlled removal of carbon by metal, the predetermined formation of non-metallic inclusions in the metal, precision alloying equalization of the temperature and composition of the entire metal mass in a significant narrow range, in the casting vessel, complete decarburization, desulfurization of clean and alloyed melts (if a metal and slag heating and mixing device is available). The use of off-site processing methods allows for high economic efficiencies due to increased yields in steelmaking furnaces, faster emptying of the furnace to melt new metal charges, reduced consumption of ferro-alloys, reduced metal contamination due to inadequate chemical composition and finished chemical composition. , improving the quality of finished products and extending the life of articles.

The choice of furnace and metal treatment method outside the furnace is determined by the grades of steel-25 to be smelted, the quality requirements of the finished metal, the technological cycle times and the casting conditions.

While electric furnace workshops are equipped with intermittent or recycled vacuum degassers, steps have been taken to manufacture cast vessel vacuum degassers equipped with metal heating and mixing 30 or vacuum oxygen blowing. Such vacuum degassers are installed, generally, in electric furnace workshops equipped with electric arc furnaces with a capacity of up to 200 t and used for the best quality bearings 35 and alloyed structural steels as well as various types of high-quality

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3 81383 for the production of low-carbon corrosion-resistant steels. Heating the metal in a casting vessel eliminates the need to overheat the metal in the furnace, which increases tear resistance and substantially increases the yield of steelmaking equipment.

Plans for new electric furnaces should take into account in advance an arrangement of equipment that will ensure complex vacuum processing of steel using neutral gases and powder reagents using electric heating and mixing of the metal and slag in the 10 casting vessels.

A method is known in the art for heating molten metal at the same time as degassing it in a vacuum and an apparatus for carrying it out (U.S. Patent No. 3,501,289, 1970, column 75-12).

The known method comprises creating a void above the surface of the molten metal for degassing and heating the molten metal with an alternating current arc created between the electrode and the melt. More complete degassing requires gas melt mixing, which is achieved by the convective heat transfer caused by the temperature difference between the arc and the rest of the metal due to the temperature of the metal mass. The combustion of an electric arc is followed by a significant heat loss through radiation, due to which the known method has a low energy efficiency in heating the melt. The implementation of such a method is significantly hampered by the necessity of creating a vacuum. In addition, the procedure described above for carrying out the method makes technically difficult to carry out metal treatment operations such as leaching, decarbonization, deoxygenation, etc., as well as desulfurization and phosphorus removal in connection with slag formation.

The known method is implemented in an apparatus comprising a vacuum chamber inside which is a container containing molten metal.

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On the side of the vacuum chamber there is a fastening means for a non-wearing electrode. The latter is adapted to move in horizontal and vertical planes. In addition, there is a means of supplying voltage from the AC voltage source to the melt.

5 The device for heating the melt during vacuum degassing is complicated by the need to keep it empty.

Currently, the treatment of melts with plasma flames has gained widespread use because it enhances heat and ali-10 transfer in melts.

A method for refining metal from smelters is known in the art (DE patent publication No. 12 17 986, 1966, column 18b).

The known method comprises oxidizing the melt with an oxidizing gas to reduce the carbon content of the melt and heating the oxidized melt with a plasma flame formed by an inert gas. At the same time, a diatomic gas is introduced into the inert gas as the active reagent. Hydrogen has been used as the diatomic 20 gas to deoxygenate the melt. Hydrogen is fed to the inert gas so much that the plasma consists mainly of hydrogen. After deoxygenation of the melt, an inert gas such as argon is again used as the plasma-forming gas.

Even the formation of plasma above the melt surface 25 causes significant radiant heat losses. This lowers the energy efficiency.

The use of the known method in the processing of metal melts is uneconomical due to the low rate of heat and mass transfer processes at the metal-plasma interface, which leads to an increase in the processing time. In addition, incomplete handling of some parts of the melt is possible.

The known method fails to guarantee the success of operations such as desulphurisation and phosphorus removal associated with slag formation due to the lack of efficient mixing of the melt at the metal-slag-plasma flame interface. Moreover, it is practically impossible to polymerize the melt by the known method due to the lack of stabilization of the temperatures and the metal composition in the whole mass, which is explained by the poor mixing which takes place only at the expense of convective heat transfer.

The known method is implemented in an apparatus comprising a casting vessel for molten metal and a plasmage-10 generator for producing low-temperature plasma, placed above the surface of the molten metal and mounted to reciprocate.

Significant radiant heat losses lead to a reduction in the service life of the refractory liner of the casting vessel due to significant thermal loads.

A process known in the art, which is closest to the present invention, is a process for processing molten metal with a direct current plasma flame and an apparatus for carrying out this process (U.S. Patent No. 3,547,622, 1970, column 75-10).

The known method includes forming a low temperature plasma by passing the plasma-forming gas through an arc, passing a low temperature plasma to a melt, namely molten steel, and heating and creating a vacuum above the surface of the melt through which a direct current is applied to form a direct current as a result, melt mixing is achieved. The melt is degassed during its vacuum treatment and stirred and heated even by low temperature plasma.

In connection with the combustion of the electric arc, significant radiant heat losses occur, which is why the known method has a low energy efficiency in the heating of the melt 35. The implementation of such a method is considerably difficult because of the necessity of creating a vacuum. In addition, the method described above for carrying out the known method makes it technically difficult to perform operations such as leaching, deoxygenation, and desulfurization and phosphorus removal operations related to slag formation. The known method of melt treatment has a low yield due to the difficulty of providing efficient mixing of the melt when the mixing requires a significant amount of energy due to the small surface area of the high temperature plasma arc-melt-10 interface where heat and mass transfer processes take place most efficiently. In addition, stationary areas may be created in the mixing process.

The known method is carried out in an apparatus comprising two vessels for molten metal arranged one on top of the other in a vertical plane and communicating with each other by two metal-carrying joints. One of the vessels is provided with a plasma generator to provide a low-temperature plasma as well, the generator being mounted for reciprocating movement in a vertical plane and arranged above the surface of the melt. A vacuum is maintained in this vessel. The equipment is equipped with a DC voltage source for producing even low-temperature plasma.

For simultaneous vacuum heating, stirring, and degassing of the molten metal, the ionized gas column of the plasma arc is contacted above the surface of the molten metal and a strong direct current is passed through the plasma arc column into the molten metal vessel. A direct current magnetic field passing through the vessel in a direction perpendicular to the direction of the arc current flow cooperates with the magnetic flux produced by said arc current and moves the molten metal along a square circumference.

The equipment used to process the melt is a complex embodiment due to the durability of the two furnaces

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7 81383 on the presence of a vessel lined with material and the necessity of creating a vacuum above the melt.

Due to the high current of the plasma arc and the recycling of molten metal, the durability of the furnace-resistant linings of metal-carrying pipes and vessels is low. It should be noted that in a given case, the treatment of the molten metal is performed periodically, because the removal of the treatment melt and the introduction of a new melt requires the opening of the vessels, which also complicates the technical process.

It is an object of the invention to provide a method and apparatus for treating molten metal, wherein a low temperature plasma flame is passed and additives are introduced into the molten metal to enhance heat and mass transfer between the low temperature plasma and the molten metal. between the additives and to improve the mechanical and functional properties of the alloys with a molten metal treatment device having a simple structure.

This object is achieved by a molten metal treatment method which includes the creation of a low temperature plasma by passing the plasma-forming material through an arc and the introduction of a low temperature plasma into the molten metal, according to the invention. and deriving the preliminarily permeable additives for the plasma.

The introduction of even low-temperature plasma inside the molten mass allows a significant increase in heat and mass transfer between the plasma and the molten metal. In this case, even for plasma, virtually all of the 81383 ki of thermal energy is consumed to heat the melt when the upwardly rising bubbles of the plasma-forming gas, which have a higher temperature than the melt, transfer thermal energy to it. Even for plasma, a higher thermal energy guarantees a higher reaction force of the gas forming the plasma, which enhances the mass transfer between the plasma and the melt. In addition, the implementation of the method allows the advantages of plasma technology to be used most effectively, namely the derivatization and derivation of slag-forming additives, which have a high reaction force obtained by heating or melting them in a plasma arc. At the same time, it becomes possible to start the molten metal treatment process at significantly lower temperatures because the plasma arc is an efficient heat source, and immersing the plasma-15 arc in the molten metal guarantees the highest thermal efficiency due to the absence of radiant heat losses.

When carrying out this method, it is desirable to use nitrogen-containing additives.

The use of nitrogen-containing additives is most effective, for example, in the alloying of corrosion-resistant and wear-resistant steels with austenitic elements such as nickel or manganese, with a view to their partial substitution.

The implementation of the presented method makes it possible to use slag-forming additives which have been preliminarily ground to a particle size of between about 0.1 and about 1.0 mm.

The speeds of the numerous processes that take place in the vessels of the steelmaking equipment (slag formation, phosphorus removal, desulfurization, etc.) lag substantially behind carbon removal and metal heating.

The use of powdered slag-forming additives preliminarily activated in the plasma arc and introduced into the molten metal mass to ensure maximum metal-slag surface development creates the conditions to achieve maximum speeds of phorhorin removal, desulfurization processes, and so on.

When slag-forming additives are used, the plasma-generating agent may suitably contain oxygen in an amount of 0 to 100% by volume of the plasma-forming agent.

Oxygen, when used in given amounts, promotes the formation of highly active ferric iron-containing lime slag, the latter being formed in the molten metal mass, and phosphorus removal processes occur as the slag particles rise upward, allowing efficient mixing of the molten metal.

This object is also achieved in a molten metal processing apparatus comprising a plasma generator 15 for producing low temperature plasma, adapted for reciprocating in a vertical plane and arranged above the surface of the molten metal, according to the invention, the plasma generator being provided with a nozzle 20 having an inlet region substantially corresponding to the outlet region of the plasma generator at the outlet of even the low temperature plasma, the length of the portion immersed in the molten metal of the nozzle being about 0.1 to about 0.8 from the height of the molten metal column.

The presence of a nozzle connected to the end of the plasma generator provides the conditions for conducting a low temperature plasma flame inside the molten metal, for introducing preliminarily activated additives below the molten metal surface, and for activating mass transfer processes. Even low-temperature plasma and the introduction of additives inside the molten metal ensures the creation of a significantly expanded surface at the molten metal-slag-gas interface, thereby significantly enhancing heat and mass transfer processes and achieving economics of slag formation and other additives.

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The plasma generator may be suitably mounted for horizontal movement.

This ensures the treatment of the entire molten metal mass, including its treatment along the outer edge, which allows a faster stabilization of the temperature and composition of the molten metal-5. It should be noted that the need to move the plasma generator in a horizontal plane is most advantageous when handling large volumes (more than 5 t) of molten metal.

It is desirable to use a blow-lamp type plas-10 magenerator. A plasma generator of this type is most suitable for introducing additives into molten metal when there is no need for significant heating of the actual molten metal. In this case, it is not necessary to use a special electrode to apply voltage to the molten metal.

A plasma generator with an external plasma arc can be conveniently used when the molten metal needs significant heating and also in the case of using high temperature melting additives which require even higher temperatures for the plasma to melt them.

The nozzle may be suitably provided with a plate having an opening in the middle concentric with the inner opening of the nozzle and vertical passageways increasing in number from the center towards the outer edge of the plane.

Said plate is mounted to enhance the heat and mass transfer between the plasma and the molten metal, which allows the gas bubbles to expand in the molten metal and to prolong their residence time. 30 This causes a more efficient distribution of gas bubbles. However, the most efficient distribution of gas bubbles is achieved when said plate is further provided with vertical passageways, which allow the upwardly moving gas bubbles to enter the corridors to be distributed and then bubble uniformly above the plate over the entire extent of the melt.

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At the boundary of the inlet area, the nozzle may be provided with an opening for the introduction of additives. Such an opening provides the desired power in conducting powdered additives into the molten metal.

In order that the invention may be more clearly understood, preferred embodiments thereof will be described more fully hereinafter with reference to the accompanying drawings, in which:

Figure 1 schematically illustrates an apparatus for treating molten metal in accordance with the invention having a Valuas-10 Tian vertical section with partial cuts in the lifting and turning mechanism of the plasma generator.

Fig. 2 is a section II-II of Fig. 1 drawn on an enlarged scale.

The disclosed molten metal treatment method also involves the generation of 15 low temperature plasma by passing the plasma generating agent through an arc.

The plasma generating agent is selected from the group consisting of argon, nitrogen, oxygen, hydrogen and / or mixtures thereof.

20 In addition, the presented method enables the introduction of low-temperature even plasma into molten metal.

In the molten metal processing process, the arc strength is maintained at a level of about 50 kW to about 5.0 MW with an amount of molten metal of about 100 kg to about 2500 kg.

The low temperature plasma flame is introduced inside the molten metal mass from its surface side at a speed of 1500 m / s, which ensures the mixing of the melt. The additives are introduced by passing them through the plasma.

Nitrogen-containing additives have been used as additives, for example pure nitrogen, a nitrogen-argon mixture or slag-forming additives which have been preliminarily ground to a size of about 0.1 to about 1.0 mm, for example leaching elemental powders (titanium, tungsten, etc.). ), lime, fluorine content, etc.

35 When slag-forming additives are used, the i2 81 383 plasma-forming agent should contain 0 to 100% by volume of oxygen from the plasma-forming agent.

The apparatus for treating molten metal comprises a plasma generator 1 (Fig. 1) for producing a low temperature plasma flame 2. The plasma generator 1 is mounted in a vertical plane for reciprocating movement and is arranged above the surface of the molten metal 3 in a special tank vessel 4, for example a casting vessel or tank. The plasma generator 1 is provided with a nozzle 5, the end of which is in contact with the molten metal 3 and whose inlet area substantially corresponds to the outlet area of the plasma generator 1 at the outlet end of the low temperature plasma 2, the length of the nozzle 0.8 from the height of 3 ko-15 lons of molten metal.

In order to ensure reciprocating movement in the vertical plane of the plasma generator 1 provided with the nozzle 5, a control device comprising a base plate 6 mounted via a ball support 7 is mounted on a bearing plane 8 to which a column 9 and lower support 10 and upper support 11 bodies are attached. The guide screw 14 is attached to the supports 10, 11 by a special lower thrust bearing 12 and a special upper thrust bearing 13. The guide screw 14 is rotated by an electric motor 15 by means of a gear 16. A nut 17 making the transfer 25 is attached to the lead screw 14.

To prevent the nut 17 from turning with the guide screw 14, the column 9 is provided with a notch 9 'holding the nut 17. A plasma generator 1 with a nozzle 5 is fixed to a bracket 18 fixed to the nut 17.

The design of the device shown allows the plasma generator 1 to move in a horizontal plane. The control device finally described rotates about its axis on the ball supports 7.

The device provides a blow lamp-type plasma generator 1 (not shown in Fig. 1) or a type of plasma generator with an external plasma arc shown in Fig. 1 35.

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If the molten metal is treated according to the first alternative, an arc is created between the anode and the cathode of the blow lamp type plasma generator 1.

If a plasma generator 1 with an external plasma arc 5 is used, an arc is created between the cathode and the molten metal 3 to which the positive pole of the DC source 19 is led by a special electrode 20. The electrode 20 can be embedded in the molten metal on its surface side or attached to a molten metal processing tank north-10 or sidewall.

At the outlet area, the nozzle 5 is provided with a plate 21 (Fig. 2), the central opening 22 of which is concentric with the inner opening of the nozzle 5 (Fig. 1).

The plate 21 may be either fixed or may have vertical passages 23 (Fig. 2), the number of which increases from the center towards the outer edge of the plate 21. In the molten metal 3 treatment process, the plate 21 is completely immersed in the molten metal 3. This enables the intensification of heat and mass transfer processes between the plasma 2 and the molten metal 3 due to the expansion of the upward gas bubbles 2 'in the molten metal 3 and the distribution of said gas bubbles. 21 through vertical passages 23. The dimensions of the outer diameter of the plate 21 vary from about 1/3 to about 1/2 of the inner diameter of the tank 4 in which the molten metal 3 is treated. Such plate sizing ensures maximum efficiency in the execution and processing of the process.

The vertical passages of the plate 21 may be annular or square in cross section.

30 The optimum dimensions of the openings in the corridors 23 increase to 8-10 mm. If the diameter of the openings (or the side of the square) increases by more than 10 mm, it can cause inconsistent operation of the passages, as the gas can primarily pass through the part of the passages arranged on the other side of the nozzle 5. When the size of the passages 23 is less than 8 mm, experiments have shown that it may lead to a "suffocation state", i.e. the passages are impermeable to gas.

The gas-plasma flame passing through the passages 23 is finely divided and rises above the plate 21 in the form of small bubbles 2 ', thus forming a well-developed gas-metal interface. In order to ensure the treatment of the entire molten metal mass above the plate 21 and to prevent all gas from passing through the passages 23 closest to the inner opening of the plate 21, said passages are arranged non-uniformly along the entire surface of the plate 21 and the number (intensity) of the passages the outer edge.

In the zone of the inlet area, the nozzle 5 has an opening 24 (Fig. 1) for the introduction of additives. This allows the powdered additives to pass through the plasma 2 as well and into the molten metal mass 3.

The apparatus for treating molten metal in a casting vessel operates as follows.

Manganese-rich steel is used for processing. Heating is performed in an induction furnace. Sula •. ·. the metal is poured from the furnace into the casting vessel 4 by means of a lifting and turning mechanism.

Water is supplied to water supply systems 25 (Fig. 1) for the cooling units of the plasma generator 1. The release of the gas forming the plasma 25 through the joint 26 is started simultaneously. The power supply 19 is turned on, the voltage is connected to the plasma generator 1, and the arc ignites.

The plasma generator 1 provided with the nozzle 5 is lowered, as a result of which the nozzle 5 sinks into the molten metal 3. The result is a flue zone in which the molten metal is treated.

For a better understanding of the present invention, specific examples illustrating preferred embodiments thereof are provided below.

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Example 1

The induction furnace produces steel with the following chemical composition,% by weight: carbon 0.36%, silicon 0.29%, manganese 0.61%. The molten metal is then poured into a 160 kg casting vessel and a plasma generator is introduced into it by means of a lifting and turning mechanism. The plasma generator is switched on with the following operating values: arc current 350Δ, plasma gas-generating gas (argon) consumption 3.2 g / s. The plasma generator nozzle is then immersed in 10 molten metal to a depth of 60 mm and the treatment is continued for a period of 10 minutes. The metal is then cast. Simultaneous metal samples are taken to test the mechanical properties. The resulting samples were normalized. The mechanical properties of the treated steel are as follows: -560 MPa, £ -23%, ψ -28%, KCV (impact strength) -460 kJ / m2, where ^ is the tensile strength, is the elongation.

For comparison, the mechanical properties of the same but untreated steel are as follows: ^ -480 MPa, ^ ', - 16%, 20 ψ - 21%, KCV (impact strength) 355 kJ / m2. Studies of the cast metal after plasma treatment made it possible to determine a 30-50% reduction in the amount of non-metallic impurities compared to steel of the same composition that had not been plasma-treated. And the non-metallic impurities 25 are ground, the correct faceting is obtained, and they are uniformly distributed in the metal.

A significant reduction in the amount of gases in the plasma-treated metal is observed. For example, a reduction in oxygen content from 0.0035% to as much as 0.0024 to 30% was observed. After plasma treatment, the steel studied has a low hydrogen content - 0.00065%, which is substantially lower than in the starting metal, where the hydrogen content is up to 0.00085%. These positive factors guarantee a significant increase in the mechanical and functional properties of the castings.

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Example 2 A wear-resistant steel made in an induction furnace and having the following chemical composition,% by weight, has been treated: carbon 1.10%, manganese-5.20%, silicon 0.83%, titanium 0.09%, sulfur 0.03 7%, phosphorus 0.074%, nitrogen 0.0072%. The molten metal is then poured into a 160 kg casting vessel in which it is alloyed with nitrogen from a plasma arc immersed in the molten metal by means of a nozzle.

10 The plasma generator is switched on according to the following operating values: arc current 300 A, plasma gas (nitrogen) consumption 4.5 g / s. The lower end of the nozzle is immersed in molten metal to a depth of 50-60 mm. Such a treatment pattern meets the efficient mixing of metal and gas, which provides a well-developed surface for heat and mass transfer. The chemical composition of the metal after blowing for a period of 12 minutes is as follows: carbon 1.07%, manganese 12.0%, silicon 0.85%, sulfur 0.032%, phosphorus 0.068%, nitrogen 0.065 20%. The mechanical properties of the steel after treatment are as follows: -760 MPa,.-570 MPa, ^-20.8%, ψ -24.1%, KCV (impact strength) -2100 kJ / m 2.

The starting steel has the following mechanical properties:? -680 MPa,? -390 MPa, ^ -19.2%, JP-23.2%, KCV (is-25 flowability) -1980 kJ / m ^.

To simulate impact-abrasion-wear conditions, experiments were performed in a ball mill consisting of two drums arranged at an angle of 45% with respect to their axis. Internal dimensions of drums: diameter 20 mm, length 320 30 mm. The drums rotate at 33 rpm. Each drum was loaded with 10 kg of 50 mm diameter (HRC 50) steel balls and 6 kg of specified size (10-20 mm on request) granite crushed stone and 10x10x25 mm steel specimens to be processed. The wear resistance assessment of steel was characterized by a relative consumption value. A sample of the starting steel was taken as the standard.

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The studies showed that according to the presented technology, the wear resistance of nitrogen-alloyed steel is 30% higher than the wear resistance of filler steel.

Example 3 5 Pig iron having the following composition,% by weight: carbon 3.98%, silicon 0.91%, manganese 0.52%, phosphorus 0.110%, sulfur 0.026% are melted in an induction furnace. From the furnace, the molten metal is poured into a casting vessel with a capacity of 160 kg. The temperature of the metal before treatment is 1260 C.

The plasma generator prepared for operation is placed in a casting vessel and placed above the molten metal. The plasma generator is switched on with the following operating values: arc current 300-400 A, voltage drop 180-250 V, plasma gas consumption 4 g / s. The plasma-forming gas consists of argon (95%) and oxygen (5 L). The nozzle is immersed in molten metal to a depth of 70-80 mm. At the same time, slag-forming additives are introduced into the molten metal in the form of a finely divided powder (particle size selected according to conditions which guarantee the usability of the plasma generator-20), having the following composition,% by weight: 80% lime and 20% fluorine slag. The total consumption of the powder is 13 kg / t.

After passing through the plasma arc, the powder particles enter the molten metal in a heated or molten state.

Once settled in the blowing zone, conditions exist for efficient mixing of the gas plasma flame containing the slag-forming agents and the molten metal. Oxygen in the form of plasma promotes the formation of highly active ferric iron-lime slag in the molten metal mass during the blowing-30 process. This results in the rapid and efficient implementation of phosphorus removal processes, which in this case occurs in the blast zone and continues as the slag particles rise upward. After a blowing period of 3 minutes, an increase in the temperature of the molten pig iron to 1285 ° C is observed.

35 After the molten metal has been treated with a gas-plasma flame, 18 81 383 slag removal, deoxygenation and metal casting operations are performed.

After treatment, pig iron has the following composition,% by weight: carbon 3.60%, silicon residues, manganese residues, phosphorus 0.01%, sulfur 0.018%.

The present invention can be most preferably used in the production of ordinary iron-carbon alloys and alloys containing expensive and rare elements, special alloys such as wear-resistant, corrosion-resistant, heat-resistant and high-temperature alloys, as well as special iron-containing and non-ferrous , for example aluminum alloys.

Claims (10)

A method for treating molten metal, wherein the low-temperature plasma flame (2) is formed by passing 5 plasma-forming substances through an arc and the low-temperature plasma flame (2) is introduced into the molten metal (3), characterized in that the low-temperature plasma flame (2) is on the inside of the mass of metal (3) from the surface side of the molten metal at a speed of about 1500 rn / s 10 for mixing the molten metal (3), and the additives which have previously passed through the plasma (2) are also introduced. Process according to Claim 1, characterized in that the nitrogen-containing substances are used as additives. Process according to Claim 1, characterized in that the additives used are slag-forming additives which have been preliminarily ground to a particle size of about 0.1 mm to about 1.0 mm. Process according to Claim 3, characterized in that the plasma-forming agent used with the slag-forming additives contains oxygen in an amount of 0 to 100% by volume of the plasma-forming agent. Apparatus for carrying out a molten metal treatment method according to claim 1, comprising a plasma generator (1) for producing a low temperature plasma (2) mounted for reciprocating motion in a vertical plane and positioned above the surface of the molten metal (3), characterized in that the plasma generator (1) is provided with a nozzle (5), the end of the 30 of which is in contact with the molten metal (3) and whose inlet area substantially corresponds to the outlet area of the plasma generator (1) at the outlet of the low temperature plasma (2), the nozzle (5) with a length of about 0.1 to about 0.8 of the height of the molten metal-35 column. 2o 81383 Device according to Claim 5, characterized in that the plasma generator (1) is mounted for movement in a horizontal plane. Device according to Claim 5 or 6, characterized in that a plasma generator (1) of the blow lamp type is used. Device according to Claim 5 or 6, characterized in that a plasma generator (1) with an external arc is used. Device according to Claims 5 to 7, or 5, 6, 8, characterized in that the nozzle (5) is provided in the zone of the outlet area with a plate (21) with a central opening concentric with the inner opening of the nozzle and with vertical passages (23). ), the number of which grows from the center towards the outer edge of the plate (21). Device according to Claim 5, characterized in that the nozzle (5) has an opening (24) in the zone of the inlet region for the introduction of additives. 2i 81383