KR20010017608A - A Slag Deoxidizer Used In Teeming Ladle And An Apparatus For Providing It And Method For Deoxidizing The Slag - Google Patents

Abstract

The present invention relates to a slag oxidizer for deoxidizing converter slag leaked to the ladle in the process of tapping molten steel from the converter into a ladle in a steelmaking process, and an apparatus for supplying the same, and a method for deoxidizing the converter slag. A slag oxidizer for generating hydrogen in a generator state, the slag oxidizer supply apparatus is an ammonia storage tank, an inert gas storage tank, a blowing line for guiding ammonia or inert gas from the storage tanks to the converter slag in the ladle, An injection lance installed at an end of the blowing line and immersed in the converter slag, and a nozzle installed at the end of the injection lance to eject ammonia or inert gas to the converter slag, and the ammonia gas to the converter slag in the ladle. Inert gas is supplied before and after Can be made cheaper manufacturing costs, effectively de-sikimyeo the converter slag in a ladle, it may also prevent the deterioration of working environment due to such as dust.

Description

Slag Deoxidizer Used In Teeming Ladle And An Apparatus For Providing It And Method For Deoxidizing The Slag}

The present invention relates to a slag oxidizer for deoxidizing converter slag leaked to the ladle in the process of tapping molten steel from the converter into the ladle in the steelmaking process, and an apparatus for supplying the same and a method for deoxidizing the converter slag.

After the molten steel is blown from the converter, the molten steel goes to the ladle, and the converter slag flows out to the ladle together with the molten steel. The converter slag leaked to the ladle contains a large amount of oxides such as FeO, MnO, P ₂ O ₅ , SiO _2, etc., and these oxides are very detrimental to the quality of molten steel.

For example, lower oxides such as FeO or MnO react with dissolved aluminum dissolved in molten steel to cause the loss of dissolved aluminum.

2Al + 3 (FeO)-> (Al ₂ 0 ₃ ) + 3Fe

2Al + 3 (MnO)-> (Al ₂ 0 ₃ ) + 3Mn

Therefore, in order to secure the appropriate dissolved aluminum in the molten steel, the amount of aluminum to be injected into the molten steel must be increased, thereby entailing a manufacturing cost burden of the molten steel. In addition, the alumina (Al ₂ O ₃ ) generated by the reoxidation reaction in the molten steel acts as a fine inclusion in the molten steel deteriorates the cleanliness of the molten steel.

On the other hand, P ₂ 0 ₅ of the converter slag is reduced in the process of raising the temperature or vacuum treatment in the ladle and dissolved again into the molten steel, causing a double phosphorus phenomenon that the content of phosphorus (P) in the molten steel rises.

Also, the converter slag of the SiO ₂ ladle within the basicity of the molten slag, calcium oxide on the molten steel in order to secure the proper basicity because it acts as a factor for lowering the (in percentages by weight of CaO / SiO ₂ defined functions as a weight percentage) (CaO Since the input amount of) should be increased, there is a disadvantage of increasing the manufacturing cost of molten steel.

Therefore, in order to remove the adverse effects of the converter slag leaked to the ladle in advance, it is necessary to deoxidize the converter slag leaked to the ladle from the converter. Used for this purpose is a slagtal acid agent.

Conventionally, pure metal aluminum or aluminum-based slag oxidizers have been used as slag oxidizers for deoxidizing converter slags on the upper ladles.

Since the metal aluminum used as the slag oxidizing agent is expensive in itself, there is a problem of increasing the cost of manufacturing molten steel or deteriorating the cleanliness of the molten steel by producing alumina as a result of the oxidation reaction of the metal aluminum.

On the other hand, the aluminum-based slagtal acid agent was prepared by combining aluminum residue (usually called aluminum dross and containing 20-40% by weight of metal aluminum) and calcium carbonate (CaCO3) or quicklime generated during aluminum refining.

In such an aluminum dross-based slagtal acid agent, the principle of slagtal acid is to reduce the metal aluminum contained in the aluminum dross by reacting with FeO or MnO, which is a lower oxide in the converter slag that flows from the converter to the ladle. However, aluminum dross is a residue generated during refining of aluminum, and when it is added to the upper ladle, the dust is not only extremely inhibited in operation due to severe dust generation, but is also injected into the mass and thus lacks agitation in molten steel. As a result, there is a disadvantage that the slag tal acid occurs locally and does not effectively deoxidize the whole slag.

In addition, the bulk aluminum dross is introduced into the molten steel through the slag layer by a natural dropping method through a chute, so that the molten steel is deoxidized rather than the slag, and as a result, the production efficiency of the molten steel is reduced. .

As described above, when metal aluminum is used as the slag oxidizing agent, metal aluminum is expensive, thereby increasing the manufacturing cost of molten steel, and when using aluminum dross slag oxidizing agent as the slag oxidizing agent, inhibiting the working environment due to excessive dust generation. There is a problem such as deterioration in slag acid efficiency, molten steel deoxidation, quicklime or calcium carbonate compounding, etc.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to effectively deoxidize converter slag in a ladle without raising the manufacturing cost of molten steel, and to prevent deterioration of the working environment due to dust generation. And a slag deoxidation method.

It is also an object of the present invention to provide a slag deoxidation method that effectively reduces FeO and MnO in slag by blowing ammonia gas into the converter slag in the ladle through the lance to deoxidize the converter slag flowing out from the converter into the ladle. .

In order to achieve the above object, according to the present invention, the slag oxidizer for deoxidizing the converter slag on the upper ladle of the molten steel flowing out from the converter to the ladle is characterized in that ammonia gas.

In addition, according to an embodiment of the present invention, an inert gas is used before and after the ammonia gas is introduced into the converter slag in the ladle as the slag oxidizer.

In addition, according to another embodiment of the present invention, the apparatus for supplying the slag deoxidizer to deoxidize the converter slag in the ladle, the ammonia storage tank, the inert gas storage tank, ladle ammonia or inert gas from the storage tank A blowing line for guiding the converter slag, an injection lance provided at the end of the injection line and immersed in the converter slag, and a nozzle installed at the end of the injection lance to inject ammonia or inert gas into the converter slag. It is characterized by.

Further, according to another embodiment of the present invention, a method for deoxidizing converter slag in a ladle filled with molten steel includes immersing the injection lance in the converter slag while supplying an inert gas, and supplying ammonia to the converter slag. Comprising a step, and stopping the supply of ammonia after the slagtal acid according to the ammonia supply, and recovering the injection lance from the converter slag while supplying an inert gas.

1 is a schematic diagram of an apparatus for supplying a slag oxidizer according to an embodiment of the present invention.

Figure 2 is a graph showing the slagtal acid rate according to the ammonia injection amount according to an embodiment of the present invention.

<Description of reference numerals for the main parts of the drawings>

11: ladle

12: ammonia storage tank

14: inert gas storage tank

16: Blowing line

18: injection lance

19: nozzle

According to the present invention, ammonia gas is used as the slag oxidizer for deoxidizing converter slag flowing out from the converter into the ladle, and ammonia gas is blown into the converter slag as the slag oxidizer.

As shown in FIG. 1, an apparatus for injecting slag oxidizing agent into converter slag includes an inert gas (nitrogen or argon) storage container 12, an ammonia storage container 14, and the storage containers 12 and 14. Injection line 16 for guiding inert gas and / or ammonia from the injection slag a in the ladle 11, an injection mounted at the end of the injection line 16 and immersed in the converter slag a And a nozzle 19 through which a lance 18 and an inert gas and / or ammonia is ejected.

When the ammonia gas is injected into the air, there is a risk of odor and damage to the skin mucous membrane. Therefore, the injection lance 18 is lowered to immerse the injection lance 18 in the converter slag or after the ammonia injection is finished. In the ascending process, inert gas must be injected to prevent ammonia from leaking into the atmosphere.

That is, when the ladle 11 filled with the molten steel b arrives in position, the inert gas valve is first opened, the ammonia valve is closed to supply only the inert gas, and the injection lance 18 is lowered to inject. When the tip of the lance 18 or the nozzle 19 is immersed in the converter slag a, the inert gas valve is closed and the ammonia valve is opened to inject only ammonia into the converter slag a. In addition, after the end of the slag acid by ammonia, the inert gas valve is opened again, and the ammonia valve is closed to supply only the inert gas, thereby preventing ammonia from flowing into the atmosphere while the injection lance 18 is raised.

On the other hand, when the tip of the injection lance 18 for injecting ammonia, that is, the shape of the nozzle 19 is in the shape of a vertical hole, the injected ammonia gas comes into contact with the molten steel b so that the slag deoxidation contributes little to the converter slag. Not only does the deoxidation efficiency drop, but the converter slag (a) is violently violated, so that the converter slag (a) may overflow the ladle (11).

Therefore, it is preferable that the shape of the nozzle 19 is inverted T-shaped or cross-shaped to prevent the ammonia gas from contacting the molten steel and to prevent the slag from overflowing.

In addition, the depth at which the injection lance 18 is immersed in the converter slag a is too shallow to agitate the converter slag and ammonia gas or is too deep to contact the molten steel b to reduce the deoxidation efficiency. Or the blown-up gas may rise and overflow the converter slab b.

Therefore, the appropriate immersion depth of the injection lance 18 is preferably about 2/3 to 1/4 of the thickness of the slag layer a in the ladle 11.

In general, ammonia is cracked at 197 ° C. as follows.

NH ₃ (g)-> 1 / 2N ₂ (g) + 3 / 2H ₂ (g)

NH ₃ (g)-> 1 / 2N ₂ (g) + 3H (g)

3H (g)-> 3 / 2H ₂ (g)

On the other hand, since the temperature of the converter slag flowing out from the converter into the ladle is about 1600 ° C. or more, decomposition of ammonia injected into the converter slag layer to deoxidize the converter slag occurs very quickly.

That is, ammonia blown in converter slag is decomposed into nitrogen and hydrogen. Hydrogen generated at this time deoxidizes the converter slag. As described above, when gas is injected into the converter slag as a slag oxidizer, the injected gas agitates the converter slag layer, and thus, the stirring efficiency is higher than that of the bulk slag phthalate into the converter slag. .

On the other hand, the hydrogen gas produced by the decomposition reaction of ammonia is very reactive as hydrogen in the generator state, unlike ordinary hydrogen gas. Here, hydrogen in the generator state means hydrogen in a state that is very active at the moment hydrogen is released from the compound, which means that hydrogen is close to the state of the atom or ion.

Hydrogen generated by the decomposition reaction of ammonia as described above reacts with FeO and MnO in the slag as follows to reduce FeO and MnO.

H2 (g) + FeO-> H2O (g) + Fe

H2 (g) + MnO-> H20 (g) + Mn

In addition, when 22.4 L of ammonia gas is decomposed at 1 mol, that is, standard state, 2 mol or 44.8 L of nitrogen and hydrogen are released, and thus a greater stirring effect can be obtained than when a simple mol of hydrogen gas is blown.

As described above, the slagtal acid by the injection of ammonia gas has the advantage of generating a large amount of reactive hydrogen generated by the decomposition of ammonia and generating a gas twice as large as the ammonia blowing amount, thereby obtaining a larger agitation effect of the converter slag. .

On the other hand, when ammonia gas is released into the atmosphere, it may irritate severe odors and skin mucous membranes and may damage the human body. Therefore, ammonia gas should be prevented from leaking to the atmosphere as much as possible.

Therefore, as shown in FIG. 1, an inert gas supply line is installed in the ammonia gas injection lance 18 to supply the inert gas until the injection lance 18 reaches the slag layer, and the injection lance 18 After being immersed in the slag layer, the inert gas supply is cut off and ammonia gas is supplied.

Likewise, in the process of degassing the converter slag by injecting ammonia gas and then raising the injection lance 18, the supply of ammonia gas is first interrupted, and then the injection lance 18 is raised while supplying an inert gas. It should not be released.

Since the ammonia gas injected into the converter slag at about 1600 ° C. rapidly decomposes into nitrogen and hydrogen at 197 ° C. or higher, no ammonia gas is released into the atmosphere.

At this time, argon or nitrogen is used as the inert gas, and since argon is more expensive than nitrogen, considering the cost side, it is recommended to use nitrogen gas for general steel refining, and to use argon for steel species that specifically regulate nitrogen. desirable.

Below. The present invention will be described in detail through examples.

100 g of converter slag was placed in a magnesia crucible using an atmosphere melting furnace, and the crucible was heated to 1600 ° C. to completely dissolve the converter slag. The slag was deoxidized by immersing the alumina tube from the top into the completely dissolved slag and then spraying ammonia gas at a rate of 0.6 l / min.

After a certain period of time, the converter slag was cooled and the slag components were divided to compare the contents of FeO and Fe ₂ 0 ₃ in the slag layer before and after slagtal acid.

Figure 2 shows the slag talciation rate according to the ammonia gas raw unit, that is, the ammonia gas injection amount / converter slag amount was defined as follows.

Here, Wa is the weight% of FeO and Fe ₂ O ₃ before slagtal acid, and Wb means the weight% of FeO and Fe ₂ O ₃ after slagtal acid.

As can be seen in FIG. 2, as the injection amount of ammonia gas increases, the slagtal acid rate increases, and when the raw unit is 0.15 L / g or more, the slag acid rate is about 80%. However, it turns out that it does not increase significantly, when injection amount is more than that.

On the other hand, Table 1 shows the slag acid efficiency and the degree of slag scattering according to the immersion position of the ammonia injection lance.

Immersion location 4/5 points 2/3 point 1/2 point 1/4 point 1/5 point Slagtal acid effect △ ○ ○ ◎ ◎ Slag Scattering Effect Almost none Weakness Weakness Somewhat Severe

(△: Normal, ○: Good, ◎: Excellent)

As the injection lance is deeply immersed in the slag layer, the slag deoxidation effect is excellent, but the workability is inferior due to the relatively high scattering of slag. Therefore, it is necessary to make the immersion position of the injection lance appropriate.

According to the present invention, in the case of converter slag deoxidation by ammonia gas, in consideration of slag deoxidation effect and workability, an appropriate injection immersion depth is optimally 2/3 to 1/4 point of the thickness of the ladle slag layer. .

In the table, the spray lance immersion position indicates the position from the interface between the molten steel and the slag layer in the ladle, where 4/5 points are shallowest in the slag layer, and 1/5 points are deepest in the slag layer.

Therefore, according to the present invention, by using ammonia gas as the slag deoxidizer to deoxidize the converter slag flowing out from the converter to the ladle, the manufacturing cost of molten steel can be reduced, and the converter slag in the ladle can be effectively deoxidized, In addition, it is possible to prevent the deterioration of the working environment due to dust generation.

The foregoing merely illustrates preferred embodiments of the invention, and those skilled in the art to which the invention pertains may make modifications and changes to the invention without departing from the spirit and gist of the invention as set forth in the appended claims.

Claims (7)

In the slag oxidizer to deoxidize the converter slag on the upper ladle of the molten steel flowing out from the converter to ladle, The slag oxidizer is a slag phthalate, characterized in that the slag phthalate to generate hydrogen in the generator state. The slag oxidizing agent according to claim 1, wherein the slag oxidizing agent is ammonia gas. The slag oxidizing agent according to claim 2, wherein an inert gas is supplied before and after the ammonia gas is introduced into the converter slag in the ladle. An apparatus for supplying a slag oxidizer to deoxidize converter slag in a ladle, Ammonia storage tank, An inert gas storage tank, A blowing line for guiding ammonia or inert gas from the storage tanks to a converter slag in the ladle; An injection lance installed at an end of the blowing line and immersed in the converter slag; And a nozzle for supplying ammonia or inert gas to the converter slag provided at an end of the injection lance. The apparatus of claim 4, wherein the nozzle has an inverted T-shaped shape or a cross shape. The apparatus of claim 5, wherein the immersion position of the injection lance with respect to the converter slag layer is 2/3 to 1/4 the thickness of the converter slag layer. In the method for deoxidizing converter slag in a ladle filled with molten steel, Immersing the injection lance in the converter slag while supplying an inert gas, Supplying ammonia to the converter slag, Stopping supply of ammonia after the completion of the slagtal acid according to the supply of ammonia, Converter slag deoxidation method comprising the step of recovering the injection lance from the converter slag while supplying an inert gas.