JPS5867817A - Heating method of molten steel - Google Patents

Abstract

PURPOSE:To heighten the temperature of molten steel with especially economical effect and in short time by means of chemical reaction heat in the mixed powder which is generated by dipping into the molten steel the vessel filled with the mixed powder of at least one kind powder of Al, Si and Mg and iron oxide-powder. CONSTITUTION:For instance, the mixed powder 1 of Al powder and iron oxide powder is filled into the cylindrical vessel 2 made of iron. In this state, the vessel 2 is dipped into the molten steel in a ladle 6, thereby heating the vessel 2 by the molten steel surrounding the vessel and igniting the mixed powder filled in the cylindrical vessel. In this stage, if the vessel surface except the edge-opening 7 of the vessel 2 is covered with insulation material 3, the powder 1 near the opening 7 is immediately ignited, but the powder 1 in the inner part has time lag until it reaches ignition temperature. Consequently, the combustion of the powder 1 in the vessel 2 proceeds gradually to the inner part from the opening part 7. The chemical reaction between Al-powder and iron oxide-powder is severe, and the temperature thereof reaches about 2,560 deg.C. Then the reaction product with high temperature is blown into the molten steel and simultaneously the molten steel is agitated. Thus the temperature of the molten steel may be eleoated in short time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a proposal for a heating method that is particularly economically advantageous and is capable of increasing the temperature of molten steel within a short time.

The mm temperature in the steel manufacturing process is an extremely important factor for properly performing the steel refining reaction and the subsequent casting process, and it is important to strictly control it.

The traditional method of controlling the temperature of this oak tree is
By raising the temperature in advance to a temperature higher than the target melt temperature in a smelting furnace or the like, and cooling it by means such as natural heat radiation or adding a coolant as necessary in the next process,
I try to keep it at the target temperature. The reason for adopting this method was that no method had been found to quickly and economically heat molten steel held in a ladle, etc.
Furthermore, once the melt #4 temperature falls below the appropriate temperature, the ### mixing or solidification process in the next milling process will not be accelerated properly, making it impossible to obtain a steel product with good quality. Because of the large economic loss, the tapping temperature around the shaft has to be higher than the target temperature.

Conventionally, as a method of heating molten steel in a holding container or the like, methods such as electric arc heating and hexagonal heating are known. However, when performing arc force U heating, it is not possible to increase the input force indefinitely, so it takes a long time to raise the temperature. The adoption of the law is not desirable. Similar problems arise even when using the 6-conduction heating method. Furthermore, these methods have drawbacks such as high operating costs and a large investment in equipment.

As mentioned above, the problem with the conventional technology is that it requires an appropriate heat source that can supply a large amount of heat that can raise the temperature of molten steel within a short period of time, and that this heat can be freely conducted into the molten steel. Due to the lack of means, the present inventors focused on this point and found a source of heat generation. The present invention was made based on this knowledge, and its gist is as follows: ht, si
, Mg powder and iron oxide powder are mixed, and the mixed powder is filled into a steel plate container and immersed in molten steel.

Iron oxide is the most suitable oxidizing agent for this purpose because it is easy to handle and the reaction product is iron, but other oxidizing agents such as saltpeter can also be mixed. The mixed powder, which has a calorific value corresponding to a predetermined temperature increase, is heated to the temperature of the molten steel and causes a rapid chemical reaction, rapidly raising the temperature of the molten steel. At this time, by covering the entire surface of the container filled with the mixed powder with a heat insulating material other than the opening provided in the container, the chemical reaction of the mixed powder inside the container will proceed gradually from the opening side of the container. Therefore, since the molten steel is heated continuously within an extremely short period of time, rather than in an instantaneous sudden drop, the heat of the chemical reaction of the mixed powder can be efficiently utilized. In addition, a handle is provided on the opposite side of the opening of the mixed powder filling container.
By holding this handle and inserting the container into the molten steel, the insertion operation can be carried out safely, and the container can be reliably kept immersed in the molten steel until the end of the reaction.

In addition, if the mixed powder filling container is made into a bullet shape and is projected into the molten steel, remote work can be performed more safely than using a handle. If one is selected, an arbitrary number of them can be placed at an arbitrary position on the surface of the molten steel in the holding container, and the molten steel can be heated extremely safely, quickly, and efficiently.

The method of the present invention will now be explained in detail based on the drawings of embodiments.

@1 Figure is an explanatory diagram showing an example of an apparatus for carrying out the method of the present invention, and l in the figure represents A! It is a mixture of powder and iron oxide powder and is filled into a cylindrical iron container. When this is immersed in f11mt in the ladle ≦, the cylindrical container will melt around the surrounding Is! (see Figure 2) At this time, the container surface other than the end opening 7 of the cylindrical filling container 1 containing the mixed powder 1 is covered with a heat insulating material 3. For example, the mixed powder near the end opening ignites quickly, but in the inner part of the cylindrical container, the sides are covered with insulation material 3, so the conduction of heat from the molten w4j is delayed until the ignition temperature is reached. Since there is a time difference between the two, the combustion of the mixed powder l in the cylinder gradually proceeds from the opening 7 toward the inner part.

The chemical reaction between the five liter powder and the iron oxide powder is intense, and the temperature is -
jOO″C, some AI is vaporized and blown out of the container from r: J7 between the end faces, and at the same time, the reaction product of high temperature red and iron oxide is blown into the molten steel. The molten steel is stirred.The pattern is as shown in 17vlI, where t is the reaction product, 9 is the filling during the reaction, and lθ is the unreacted filling.0 The reaction product is removed from the cylindrical container. In order to cause the powder to eject violently, it is necessary to add a substance with a relatively high vapor pressure, such as M, to the mixed powder.
It is effective to mix powders such as g and aa.

Note that the handle is provided to hold the cylindrical container in the molten steel until the end of the reaction, but the container is introduced into mw at high speed and 'f4! This handle is not necessarily required if it is possible to reach the area. However, since the above reaction generally requires 5θ to 1θ seconds, it is desirable to hold the container in the molten steel with this handle.

The heat insulating material 3 is effective in allowing the above-mentioned reaction inside the container to proceed gradually from the opening at the end of the container, but if the reaction of the filling mixture in the container occurs almost simultaneously and proceeds explosively, the heat insulating material 3 is effective. Material 3 may be removed.

However, according to the experience of many experimental examples, when the rate is -1 to 1, it is dangerous because a large amount of gas is generated and oozes, and a part of the molten steel may be blown away. Therefore, it is an extremely effective and appropriate method to almost instantaneously convert this exothermic reaction into a bullet-shaped container and to project this bullet-shaped container into the molten steel at high speed.

Next, the implementation sequence of the method of the present invention will be explained.

A total of 9 gw of mixed powder of U powder j9 and iron oxide powder 27 to 9 was attached to one end with an iron handle with a diameter of about 〃cm,
A cylindrical container made of a steel plate having a length of about 5OcllI was filled with the mixture, and the outer surface of the container was coated with a refractory material to provide heat insulation. Molten steel! The results showed that the temperature of the molten steel increased by 12°C as a result of inserting it into molten steel in a holding container holding a ton of steel and holding it until the reaction was completed.

The heating method of the present invention can be applied to all molten steel holding containers that require heating, such as ladle refining containers, converters,
In addition to small experimental melting furnaces, it is suitable for degassing vessels, such as RH and DH type degassing tanks, etc.11.It can be used to quickly heat molten steel, and is an extremely effective method for heating molten steel industrially. It is.

[Brief explanation of the drawing]

1wJ is an explanatory diagram of a container filled with mixed powder for heating, FIG. 2 is an explanatory diagram showing the state in which the container is immersed in molten steel, and FIG. 3 is an explanatory diagram showing the state of the mixed powder during reaction. l...mixed powder, c...filling container, 3...insulating material, da...handle, j...molten steel, t...ladle, ? ...
End face opening, l...reaction product, 9...filler during reaction, IQ...unreacted filler. Patent applicant: Kawasaki Steel Corporation

Claims (1)

[Claims] 1. A container filled with a mixed powder of at least one of aluminum, silicon, and magnesium powder and iron oxide powder is immersed in molten steel, and the chemical reaction heat of the mixed powder generated A method for heating molten steel characterized by heating molten steel. 2. The entire surface of a container filled with mixed powder having an opening except for the opening is covered with a heat insulating material, and the chemical reaction of the powder filled in the container is gradually progressed from the end face side of the opening of the container. A method for heating molten steel according to claim 1. 3. Claim 2, characterized in that a filling container with a handle provided on the opposite side of the opening is used, and the container is kept immersed in molten steel until the reaction path of the mixed powder in the container is reached. The method of heating molten steel described. 4. A method for heating molten steel according to claim 1, characterized in that the mixed powder filling container is shaped like a bullet, and the mixed powder is filled into the bullet-shaped container and immersed in the molten steel bath at high speed.