JPS58161731A - Method for blowing mixture of flux and inert gas - Google Patents

Abstract

PURPOSE:To prevent the clogging of the inside of a lance that occurs in the melting of a flux in the stage of blowing a mixture of a flux and an inert gas for refining, by cooling the mixture to the temp. at which the flux in the mixture begins melting or below. CONSTITUTION:In refining of molten nonferrous metals or alloys thereof, the top end of a lance 1 is immersed in the molten metal 6 in a melting furnace 5. The top end of the lance 1 is installed in a cooling part 2 to be cooled with cooling water 4 to cool a mixture of a flux and an inert gas to the temp. at which said flux begins melting or below. The cooled mixture is then blown into the molten metal 6. The diameter of the lance 1 is made smaller than the diameter of the part 2 between A and B of the lance 1 to increase the transfer speed or the like, so that heating time of the mixture is reduced. The clogging in the lance 1 that occurs in the melting of the flux is thus prevented, whereby the blowing work is stabilized and the yield of the flux is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for blowing flux-inert gas mixtures.

Generally, molten metals of non-ferrous metals and non-ferrous alloys.

For example, aluminum and molten aluminum alloys contain inclusions and various gases that are mixed in from the charged raw materials, mixed during the melting process, or newly generated, and as a result, the products have poor toughness. There are problems such as deterioration and surface defects.

Therefore, in order to remove these inclusions and degas, it is said that refining using a halogen gas, such as chlorine gas or fluorine gas, after the completion of melting is effective. Originally, it was desirable to use these halogen-based gases directly, but in view of their high toxicity, a granular flux containing half of the chlorides and fluorides is usually used, and the Refining is performed using various halogen-based gases that are melted and generated by blowing into the gas. That is,
Specifically, powdered slack is charged into a flux-inert gas simultaneous blowing device, and the slack is preliminarily poured.

It is transported to just before the molten metal using an inert gas whose pressure is adjusted, and from there it is blown into the molten metal using a steel lance at the tip.

However, in this blowing method, the steel lance at the tip creates a temperature gradient depending on the temperature at each location, such as in the molten metal, near the molten metal, and at steep points from the molten metal. In other words, the steel cracking lance has a temperature gradient from the temperature of the molten metal to room temperature, and the powder flux melts according to the temperature, so that the powder flux is half-dissolved. Problems arise in that the material melts, or more particularly, becomes molten and adheres to the inner wall of the blowing lance, clogging the blowing lance, or reducing the inner diameter of the lance, reducing blowing efficiency.

That is, to explain this with reference to Figure 1, one end of the lance R is at a high temperature A on the surface of the molten metal, but the other end is at room temperature B, with a degree gradient of the lance RK, so that the molten metal is blown into the lance R. The flux-inert gas begins to melt at 7 lux in the lance R, and as mentioned above, it melts and adheres to the inner wall of the lance in a semi-molten state, and this adhesion layer continues to grow as time passes, and the lance This causes R clogging (higher temperature than point E in the diagram). This results in a decrease in flux yield. If this lance is clogged, not only will the yield of 7 lacs decrease, but it will also cause significant losses such as damage to the lance itself, loss, or interruption of operation.

Note that D is the flux melting start temperature.

As mentioned above, the present invention solves the problem that flux melts and clogs the lance and reduces the injection efficiency in the conventional injection of non-ferrous metal and inert gas mixture. It is about providing law.

Characteristics of the method for blowing a 7lux-inert gas mixture according to the present invention: d1 non-ferrous metal;

In refining the molten alloy, when blowing a refining flux-inert gas mixture, the mixture is
The purpose is to cool the lux to a temperature below the melting start temperature of the lux and then blow it.

The method of blowing the flux-inert gas mixture according to the present invention will be explained in detail below.

That is, the lance itself for transferring the flux-inert gas mixture and injecting it into the molten metal is cooled to below the melting start temperature of 7 lux to prevent clogging inside the lance due to melting of the flux.

As shown in FIG. 2, the entire length of the lance R or the lance R excluding the vicinity of the molten metal is cooled with water, gas, etc.
The temperature is maintained below the temperature at which the flux begins to melt, and a flux-inert gas mixture is blown into it. Therefore, both the flux and the inert gas are cooled, and the powdery 7Lax is transferred inside the lance together with the inert gas without being melted, so that clogging of the lance 9 can be prevented.

Thus, in the method of blowing a 7lux-inert gas mixture according to the present invention, non-ferrous metals, and.

As the alloy, for example, flux conveniently used in refining aluminum and molten aluminum alloy is salt (
It is composed of an E compound, a fluoride, and a combustion improver, and
In the flux-inert gas simultaneous injection method, particles of these simple compounds are transported in an inert gas with significantly less interaction.

For this reason, it is necessary to prevent the flux from melting, keep each simple compound below its melting point, and transport it as a solid. It is necessary to perform the blowing as follows.

Table 1 shows the melting points of commonly used compounds.

Table 1 FIG. 6 is the ninth schematic explanatory diagram for carrying out the method of blowing a flux-inert gas mixture according to the present invention. That is, the tip of the lance 1 is immersed in the molten metal 6 in the melting furnace 5, and the lance 1 is
The upper end of the 7
A mixture of 7 lux and inert gas is transferred from the lux-inert gas simultaneous injection machine as shown in the stamp, and in the cooling section 2, 7 lux is cooled from the outside of the lance 1 to below the melting start temperature and blown into the molten metal 6. It is possible.

Then, A of the lance 1 at the terminal end of the cooling section 2 shown in FIG.
Since this part is in the atmosphere of being heated due to the high temperature of the molten metal 6, it is necessary to keep the distance between the hot metal 6 and the surface B of the hot metal 6 as short as possible so that there is no time for the flux to melt. .

However, if the lance 1 at the end of the cooling section 2 is close to the surface of the molten metal 6, no melting will occur within the 7 lux lance 1, but if the cooling section 2 is close to the surface of the molten metal 6, the cooling section 2 will be damaged by the molten metal 6°. However, in the worst case, cooling water 4 turns into molten metal 6.
This could lead to a major accident due to contact with In order to prevent the temperature from rising between A and B, the diameter of lance 1 is made smaller than the diameter of lance 1 of cooling section 2 between A and B to increase the transfer speed and shorten the heating time. , and the A-B cabinet of Lance 1, for example, A
Naturally, for tz Os type and fri<, it is necessary to take measures such as covering with a multi-component type heat insulating material containing At2O3 for insulation.

Furthermore, this cooling temperature varies depending on the temperature of the molten metal, the cooling position, etc., but for example, aluminum.

When refining aluminum alloys, it is necessary to maintain the melting point below the lowest melting point of the single compound that makes up the flux, as described above, depending on the type of flux being blown into.
If this temperature is exceeded, the slack will melt in the lance, making it impossible to achieve the object of the present invention.

Next, an embodiment of the method for blowing a flux-inert gas mixture according to the present invention will be described.

Molten metal used in examples At-Mg alloy (5182) Weight
20 tons temperature 740℃ 7 lux NaCL-AtFs -KAjF4-C
aCOs system (melting start temperature approx. 574℃) Seed line Slack view 20 Ready-to-use gas N3 Pressure IIL5 Q/aj Flow rate 400t/min Cooling S Length 111t Outer diameter
1001+1φ Lance outer diameter 251i1φ Lance inner diameter 20uφ Material Cooling section Stainless steel lance Ordinary steel A-B interval 1m+ Temperature Inside the lance in the cooling section 20℃ Inside the lance on molten metal surface B 120℃ Room temperature 50℃ Use water or gas as a cooling medium can do.

7Lax does not melt in the lance and lance clogging does not occur, so the slack yield (yield of slack) is 2.
It improved by 5%.

As explained above, since the flux-inert gas mixture blowing method according to the present invention has the above-mentioned configuration, the slack is maintained at a temperature below the melting start temperature and sent into the lance. Therefore, the blowing operation of the 7lux-inert gas mixture which can prevent clogging due to melting in the lance is stabilized, and the yield of flux is also improved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the lance internal temperature and lance position in the conventional method, FIG. 2 is an explanatory diagram showing the lance internal temperature and lance position in the slack-inert gas mixture blowing method according to the present invention, and FIG. The figure is a schematic diagram for explaining the method of blowing a flux-inert gas mixture according to the present invention. 1 - lance, 2 - cooling section, 3 - simultaneous blower, 4 - cooling water, 5 - melting furnace, 6 - molten metal. 1st City Figure 2 Figure s3

Claims (1)

[Claims] When refining non-ferrous metals and molten alloys thereof, when a refining fluff or an inert gas mixture is blown into the molten metal, the mixture is cooled to below the melting start temperature of 7 lux in the mixture. A method of blowing a flux-inert gas mixture at a rate of 1%.