KR20160106132A - Secondary material for steel refining - Google Patents

Abstract

The amount of aluminum nitride contained in the steel refining auxiliary material supplied to the molten iron together with the lime to accelerate the desulfurization reaction in the molten iron is set to 20 wt% or more as a weight percentage (wt%). At this time, a mixture of lime and steel refining auxiliary material is used as a desulfurizing agent, and the amount of the steel refining auxiliary material in the desulfurizing agent is adjusted to, for example, about 5.0 wt% as a weight percentage.

Description

[0001] SECONDARY MATERIAL FOR STEEL REFINING [0002]

The present invention relates to a steel refining auxiliary material for promoting a desulfurization reaction of molten iron.

Currently, calcium oxide (lime) is widely used as a desulfurizing agent for charcoal. Further, in order to promote the desulfurization reaction of the molten iron by the lime, an auxiliary material for steel refining made of aluminum (ash) is used in combination with lime.

The aluminum material is obtained from, for example, an oxide layer formed on the surface of the molten metal when the aluminum material is dissolved. This oxide layer is referred la aluminum dross (aluminum dross), and contains about 60 ~ 70wt% of metal aluminum (Al M.) in mass percentage. aluminum When an aluminum material is obtained from the dross, it may be recovered as a remnant remaining after recovering the metal aluminum by the metal aluminum recovery process . Here , the aluminum material as a steel refining auxiliary material contains about 30 wt% of metal aluminum as a percentage by mass in order to effectively promote the desulfurization reaction of the molten iron .

Patent Document 1 discloses such an aluminum material.

The aluminum material disclosed in Patent Document 1 is an aluminum material added to a molten iron desulfurizing agent and contains aluminum oxide and metallic aluminum and has a sulfur content of 0.05 mass%  Hereinafter, when the content of chlorine is 0.5 mass%  Or less.

Japanese Patent Application Laid-Open No. 2006-283083

Conventionally, when an aluminum material is used as an auxiliary material for steel refining, it is preferable that the content of metal aluminum is included to some extent. For example, when the content of aluminum metal is about 10 wt%, it is considered that it is difficult to use aluminum material as a desulfurizing agent Has come. Therefore, in the aluminum material disclosed in the above-mentioned Patent Document 1, it is preferable that the content of metallic aluminum is 20 wt% or more for the purpose of promoting the desulfurization reaction. In general aluminum material, about 30 wt% have.

That is, since the recoverable metal aluminum is originally left in the aluminum material, there arises a problem that the recovery efficiency in the metal aluminum recovery process is lowered.

In addition, in the conventional aluminum material containing a large amount of metal aluminum, there is a risk of spontaneous ignition at the time of storage, and it is necessary to pay attention to ensuring safety at the time of storage.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a steel refining auxiliary material exhibiting a desulfurizing effect of a molten iron and having a low risk of ignition during storage.

In order to achieve the above object, the present invention adopts the following technical means.

The steel refining auxiliary material according to the present invention is a steel refining auxiliary material which is supplied to a molten iron together with lime and promotes a desulfurization reaction in the molten iron and is characterized in that the amount of the contained aluminum nitride is 20 wt% .

Here, the amount of the metallic aluminum contained may be 10 wt% or less.

Here, the amount of silicon dioxide contained may be 2 wt% or less.

Further, the steel refining auxiliary material described above may be produced from aluminum dross treated in an arc.

Also, the amount of the metallic aluminum contained therein may be 0 wt% or more and 10 wt% or less, and the amount of the aluminum oxide contained may be 80 wt% or less.

According to the steel refining auxiliary material of the present invention, the risk of ignition during storage is lowered while exhibiting the desulfurizing effect of the molten iron.

1 is a graph showing a desulfurization promoting effect of a steel refining auxiliary material according to the present embodiment,
2 is a diagram schematically showing a cross-section showing an internal configuration of an arc described in an embodiment of the present invention.

Embodiments of the present invention will be described with reference to the drawings.

The embodiments described below are illustrative of specific embodiments of the present invention, and the present invention is not limited to the specific examples. Therefore, the technical scope of the present invention is not limited to the contents disclosed in this embodiment.

Hereinafter, a steel refining auxiliary member according to the present embodiment will be described.

The steel refining auxiliary material according to the present embodiment is used for the desulfurization treatment in the iron refining process. In the desulfurization treatment for removing the sulfur S in the charcoal, lime (CaO, calcium oxide) is added (added) to the charcoal. The added calcium (Ca) in the lime is combined with the sulfur S in the charcoal according to the chemical reaction formula shown in the following formula (1), and the sulfur S is recovered (desulfurized) from the charcoal.

[Equation 1]

At the same time as the addition of the lime or before mixing with the lime, a steel refining auxiliary material for accelerating the desulfurization reaction according to Equation (1) is added (added) to the molten iron. As a conventional auxiliary material for steel refining, an aluminum material containing about 30 wt%, for example, a weight percentage (wt%) of metal aluminum as disclosed in the above-mentioned Patent Document 1 is used. The added metal aluminum is desorbed from the lime (CaO) (deoxidation reaction) in accordance with the chemical reaction formula (desulfurization reaction) shown in the following formula (2) Promote.

&Quot; (2) "

The inventors of the present invention have found that aluminum nitride (AlN) is deoxidized at least in the molten iron by a deoxidation reaction equivalent to that of metallic aluminum ) To the lime (CaO).

When aluminum nitride is added (added) to the molten iron as a steel refining auxiliary material immediately after or simultaneously with the addition of the lime in the molten iron, the added aluminum nitride is calcined by lime (CaO (Deoxidization), thereby accelerating the binding (desulfurization) between calcium Ca and sulfur S in the molten iron.

&Quot; (3) "

As described above, aluminum nitride (AlN) can be used as a steel refining auxiliary material. For aluminum nitride as a steel refining auxiliary material, it is preferable to use a reagent whose purity is close to 100% or 100%, but the desulfurization reaction shown in the formula (3) is a method in which a material containing aluminum nitride in an amount of 20 wt% By using it as a supplementary material, the desulfurization reaction is sufficiently promoted.

1 is a graph showing a desulfurization promoting effect of a steel refining auxiliary material according to the present embodiment. The graph of Fig. 1 shows the case where the lime (CaO) is added to the molten iron as a desulfurizing agent with respect to the change with time in the concentration of the sulfur (S) in the molten iron as a white circle, and the steel refining subsidiary material And a mixture of lime and a refractory agent containing 5.0 wt% of steel refining auxiliary material in a molten iron is shown in black circles.

Referring to the graph of FIG. 1, the concentration of sulfur S in the charcoal is about 300 ppm immediately after the addition of the desulfurizing agent having a desulfurization treatment time of 0 min (min), both in the case of lime and the mixture. Thereafter, at the time of the desulfurization treatment time of 10 minutes, the concentration of sulfur S was reduced to about 150 ppm in the case of lime, but in the case of the mixture, the concentration of sulfur S was lowered to about 10 ppm have.

That is, when the desulfurizing agent containing the steel refining auxiliary material according to the present embodiment is used, the desulfurization reaction speed is accelerated several times as compared with the case where the steel refining auxiliary material is not contained.

Here, as an example of the steel refining auxiliary material including aluminum nitride in the order of tens of wt%, the arc furnace will be described.

The arc furnace is made of aluminum nitride (AlN), for example, as residues produced by recovering metal aluminum from a well-known aluminum dross (aluminum dross) treated with the arc furnace 1 shown in Fig. 2, . The arc (1) of FIG. 2 energizes between the carbon electrodes (cathode and anode) 2a and 2b inserted into the furnace body to generate an arc, thereby heating, dissolving It is no. From the melted aluminum raw material, the molten metal (3) and the arc material (4) to be deposited on the molten metal (3) are generated.

In addition, the acro material 4 has a particle diameter suitable for use as a steel refining auxiliary material, and the particle diameter of the acro material 4 can be measured by sieving. For example, when an acro material 4 having a nominal sieve size of 10 mm and passed through a sieve (according to a metal mesh, according to JIS 8801-1) has a diameter of 10 mm or less, .

The particle size (grain size) of the acrolein material 4 used as the auxiliary material for steel refining of the present invention is preferably 12 mm or less, more preferably 3.5 mm or less from the viewpoint of desulfurizing ability and the like. Hereinafter, the results of evaluation of the acrolein as an auxiliary material for steel refining with respect to the desulfurizing ability and the ignitability will be described.

A plurality of acro materials having different contents of components were prepared, and the desulfurizing ability and the ignitability were evaluated. Analysis of the content of the arc material components, mainly, the amount W _{M .Al} (wt%) of the total amount _T.Al W (wt%), metallic aluminum (M. Al) of aluminum (Al) contained in the arc member, performed by paying attention to the amount, and the amount W _Al2O3 (wt%) of aluminum oxide (Al ₂ O ₃₎ of aluminum nitride (AlN).

First, the total amount W _T.Al of aluminum (Al) was measured by ICP emission analysis from the entire acro material. Next, the amount W _{M .Al} (wt%) of metal aluminum (Al M.), was detected in accordance with the clear methanol decomposition -ICP emission spectrometry. It is also assumed that N in the residue after the methanol decomposition by cancellation is measured by the neutralization titration method and that the detected amount _N N of nitrogen _N is all derived from aluminum nitride (AlN). It is assumed that the amount of aluminum (Al ₂ O ₃ ) Al is obtained by subtracting the amount of metallic aluminum ( _M.Al ) from the total amount W _T.Al of aluminum (Al) and the amount of Al in aluminum nitride (AlN).

With these assumptions the equation (4) to, based on, and calculate the amount W of _Al2O3 aluminum oxide (Al ₂ O _3).

&Quot; (4) "

Next, as the auxiliary steel material (subsidiary material) for steel refining in accordance with the present embodiment, the desulfurizing ability was evaluated using the five types of acrodes shown in Examples 1 to 7 and the AlN reagent shown in Example 8. In addition to these Examples 1 to 8 and Comparative Examples 1 to 4, the desulfurizing ability was evaluated, and the evaluation results obtained are as shown in Table 1 below.

The particle diameters (particle size) of the auxiliary materials used in Examples 1 to 8 below are not more than 3.35 mm in both the acro material and the aluminum material.

[Table 1]

The steel refining auxiliary materials of Examples 1 to 8 were adjusted so that the amount of aluminum nitride (AlN) contained therein was 20 wt% or more. Particularly, the steel refining auxiliary materials of Examples 1 to 7 contain an amount of aluminum nitride of 20 wt% or more and 50 wt% or less, and the amount of aluminum nitride contained in the steel refining auxiliary material of Example 8 is 100 wt% % AlN reagent.

The amount of the metallic aluminum (M.Al) contained in the steel is adjusted so as to be approximately 0 wt% or more and 10 wt% or less in the steel refining auxiliary materials of Examples 1 to 8. The content of aluminum oxide (Al2O3) contained in the steel is preferably 30 wt% or more and 80 wt% or less, but it is adjusted to be approximately 40 wt% to 50 wt% in the steel refining auxiliary materials of Examples 1 to 7.

In the present invention, 100 wt% of AlN may be used because AlN is contained in an amount of 20 wt% or more. However, by adjusting the content of AlN on the basis of an ordinary auxiliary material, AlN may be used in an amount of 20 wt% or more. The usual auxiliary material contains 90 wt% or more of mainly Al ₂ O ₃ : 20 to 80 wt%, M. Al: 10 to 50 wt%, AlN: 20 wt%, SiO ₂ : 10 wt%, and MgO: 15 wt% , And inevitably MnO, K ₂ O, Na ₂ O and the like.

The evaluation shown in Table 1 was carried out under the following conditions. The carbon concentration [C] = 4.2 to 4.6 wt%, the silicon concentration [Si] = 0.3 to 0.8 wt%, the manganese concentration [Mn] = 0.1 to 0.4 wt%, the phosphorus concentration [P] = 0.1 to 0.2 wt% [S] = 0.025 ~ 0.035wt% of example 1 of the auxiliary component as shown in to 7 of the molten iron in the melting furnace 300㎏, with respect to the lime (CaO), and table 1 (Al ₂ O _3, AlN, Al M. (10 kg / charcoal ton) mixed with the steel refining auxiliary material according to the present embodiment, which contains the above-mentioned steel material, At this time, the mixing ratio of the lime and the auxiliary material is the same as the mixing ratio shown in Examples 1 to 7 of Table 1.

After introducing the desulfurizing agent into the molten iron, for example, the desulfurization is started by a mechanical agitation method using a stirring blade, which is disclosed in Japanese Patent Laid-Open Publication No. 2011-256445, and the molten iron after being treated at 1350 캜 for 10 minutes Sulfur concentration [S] was sampled.

Table 1 also shows the results of evaluation based on whether or not the sampling result of the sulfur concentration [S] shows a concentration of less than 20 ppm.

The evaluation results shown in Table 1 will be examined below.

As compared with the conventional steel refining auxiliary material (aluminum material) shown in Comparative Example 1, the steel refining auxiliary material (acro material) according to the present embodiment shown in Examples 1 to 7 has sulfur The sampling results of the concentration [S] were all less than 20 ppm, showing a desulfurization effect equal to or higher than that of the aluminum material. That is, even if AlN and M. Al are mixed, it is obvious that the sulfurous ability is manifested, so that the acro material and the aluminum material can be mixed and used.

In Examples 1 to 3, although the amounts of aluminum nitride (AlN) were irregularly distributed in different amounts, all of them were made 20 wt% or more. Thus, when the amount of aluminum nitride (AlN) was sufficiently contained, the sampling results of the sulfur concentration [S] shown in Table 1 were all less than 20 ppm, and the acrolein showed effective desulfurization effect.

2.5: Examples 1, 4, in 5, of the auxiliary components _{(Al 2 O 3, AlN,} M. Al) is using the same arc furnace material, the compounding ratio of lime material and the arc 95: 5, 92.5: 7.5, 97.5 Change. Even when the mixing ratio of lime and acro material was changed in this manner, all of the sampling results of the sulfur concentration [S] shown in Table 1 were less than 20 ppm, and the acrolein showed effective desulfurization effect.

In Example 8, an AlN reagent containing 100 wt% of aluminum nitride was used. Even when an AlN reagent not containing aluminum oxide (Al ₂ O ₃ ) or metallic aluminum (M.Al) is used, the sampling result of the sulfur concentration [S] is 5 ppm, and the AlN reagent has a desulfurizing effect I did it. As can be seen from this, the AlN concentration is preferably as high as possible.

In Comparative Examples 2 to 4, the components in the auxiliary materials are significantly different from those in Examples 1 to 7. In Comparative Example 2, since the auxiliary material not containing aluminum nitride (AlN) and metallic aluminum (M.AI) with the amount of aluminum oxide of 100 wt% was used, the sampling result of the sulfur concentration [S] was 51 ppm, .

The auxiliary material of Comparative Example 3 contains 5 wt% of aluminum metal (M.AI), and the auxiliary material of Comparative Example 4 contains 15 wt% of aluminum nitride (AlN). However, all of the samples of sulfur concentration [S] Was more than 30 ppm, and sufficient desulfurization effect was not exerted. This is considered to be the reason why the amount of metal aluminum (M. Al) or aluminum nitride (AlN) was not sufficient. As described above, aluminum oxide is formed simultaneously with aluminum nitride because the arc furnace is heat-treated in the atmosphere. From the above results, it is necessary that the amount of aluminum oxide is 80 wt% or less from the viewpoint of desulfurizing ability.

The amount of silicon dioxide (SiO ₂ ) in the desulfurizing agent is preferably as low as possible. SiO ₂ reacts with CaO to form a reaction phase having a high melting point such as 2CaO · SiO ₂ to inhibit the desulfurization reaction. Therefore, the SiO ₂ concentration is preferably as low as possible. In Example 7, the amount of SiO ₂ contained exceeds 2 wt%, which indicates that the desulfurizing ability is lowered as compared with Examples 1 to 6. Therefore, the content of SiO _{2 in} the auxiliary material is preferably 2 wt% or less.

Next, the ignitability (ignitability) was evaluated using the four kinds of acrodes shown in Examples 9 to 12 as auxiliary materials for steel refining (subsidiary materials) according to the present embodiment. With respect to Examples 9 to 12 and Comparative Example 5, the ignitability was evaluated, and the evaluation results obtained are shown in Table 2 below.

In Table 2, Example 9 shows the results for an arc material having components in the subsidiary material equivalent to those in Example 1 in Table 1. [ Likewise, Example 10 is the same as that of Example 2, Example 11 is the same as Example 3, Equivalent arc furnace, Example 12 shows the results for an arc furnace equivalent to that of Example 6. Comparative Example 5 shows the results for an aluminum material having a component in the subsidiary material equivalent to Comparative Example 1.

[Table 2]

The evaluation shown in Table 2 was carried out under the following conditions.

The minimum ignition energy MIE (minimum ignition energy), which is one of the indicators of the ignitability of the powder, was used to evaluate the ignitability of the aluminum material and the arc material. For the MIE measurement, a spark ignition test device (Hartmann type, MIKE-3) conforming to the IEC standard, which is standardized at home and abroad, was used.

In such an apparatus, compressed air (0.7 bar) in the receiver tank (1.28L) blows up the dust placed on the bottom of the explosion container (1.2L) made of glass while opening the solenoid valve, Makes a dust cloud. To this, a capacitor of 20 pF to 20 nF was charged with a direct current high voltage power source of 15 kV at maximum to produce a predetermined discharge energy, and the ignition performance was evaluated by applying such discharge energy to the dust cloud. Further, it was judged that the case where a flame of 50 mm or more was propagated in the explosion vessel was ignited, and the respective minimum ignition energies were measured.

The results of the measurement are shown in Table 2, and it is judged that the minimum ignition energy obtained is less than 50 mV and the ignitability (ignitability) is low. Is judged to be " DELTA ", and if it is less than 10 mV, it is determined that the ignitability is very high, and "x"

The evaluation results shown in Table 2 will be examined below.

The steel refining auxiliary material (acro material) according to the present embodiment shown in Examples 9 to 11 has a minimum ignition energy of 50 mV or more and a comparatively low minimum ignition energy of 4 mV . This is because the amount of metallic aluminum (M.Al) contained in the steel refining auxiliary material is less than 10 wt% and is less than 30.4 wt% of the amount of metallic aluminum (M.Al) in Comparative Example 5 .

In Example 12, as compared with Examples 9 to 11, the amount of metallic aluminum (M. Al) was slightly increased to exceed 10 wt%. In Example 12, as the metal aluminum (M.Al) increases, the minimum ignition energy is lowered to 23 mV below 50 mV. That is, when the amount of metal aluminum (M.Al) exceeds 10 wt%, it is difficult to say that the ignitability is very low because it is a little ignited as compared with Examples 9 to 11. From the viewpoint of ignitability, the amount of metallic aluminum (M.Al) is preferably 10 wt% or less.

The aluminum material of Comparative Example 5 contains 30 wt% or more of metallic aluminum (M.Al), and the minimum ignition energy is 4 mV. As described above, the aluminum material is a supplementary material which is very likely to ignite even when compared with the arc materials of Examples 9 to 12, and care is required in its handling.

As described above, the arc furnace which is the auxiliary material for steel refining according to the present embodiment includes aluminum nitride (AlN), thereby exhibiting the desulfurizing ability to the same extent as that of the conventional aluminum refining auxiliary material, It can be said that it is difficult to ignite (ignite) than the aluminum material, so that the safety is excellent and storage is easy.

Table 3 below compares the desulfurizing ability and the handling property (difficult to ignite) with respect to the aluminum material and the acro material. It can be confirmed that the arc furnace is superior in handling property while exhibiting an equivalent desulfurizing ability as compared with an aluminum material.

[Table 3]

In addition, an advantage of using an acro material is described below. Since the aluminum material is oxidized by the atmosphere during storage in the aluminum material, the deoxidation reaction by the metal aluminum proceeds before being introduced into the hot molten iron, and there is a possibility that the desulfurizing ability is lowered. On the other hand, the aluminum nitride of the acro material is stable in the atmosphere, and is put into a hot molten wire and the deoxidation reaction proceeds for the first time, so there is no need to worry about the deterioration of the desulfurizing ability during storage.

Furthermore, the embodiments disclosed herein are to be considered in all respects as illustrative and not restrictive. Particularly, in the presently disclosed embodiments, matters that are not explicitly disclosed, for example, operating conditions and operating conditions, various parameters, dimensions, weights, volumes, etc. of constituent elements do not deviate from those usually practiced by those skilled in the art , And a value that can be easily assumed is employed if the person is ordinary persons.

For example, the steel refining auxiliary material according to the above-described embodiment contains aluminum nitride (AlN) as a substance promoting the desulfurization reaction by a deoxidation reaction. However, instead of aluminum nitride (AlN) AlBr ₃₎ or aluminum chloride (AlCl _3), etc., may be used an aluminum compound which is decomposed at a relatively low temperature with respect to the temperature of the molten iron. A steel refining auxiliary material using aluminum (AlBr ₃ ) or aluminum chloride (AlCl ₃ ) can promote the desulfurization reaction by a deoxidation reaction by almost the same mechanism as the desulfurization reaction of the above-described formula (3).

The present application is based on Japanese Patent Application (Patent Application No. 2014-021555) filed on February 6, 2014, the contents of which are incorporated herein by reference.

(Industrial availability)

The steel refining auxiliary material of the present invention has a desulfurizing effect equal to or higher than that of a conventional aluminum material and is low in the risk of ignition during storage, and is useful for use in a refining facility.

1: arc 2a, 2b: carbon electrode
3: molten metal 4:

Claims (5)

1. A steel refining auxiliary material supplied to a molten iron together with lime to accelerate a desulfurization reaction in the molten iron,
Characterized in that the amount of aluminum nitride contained is 20 wt% or more as a weight percentage
Steel refining subsidiary materials. The method according to claim 1,
And the amount of the metallic aluminum contained is not more than 10 wt%
Steel refining subsidiary materials. 3. The method according to claim 1 or 2,
And the amount of silicon dioxide contained is not more than 2 wt%
Steel refining subsidiary materials. The method according to claim 1,
Characterized in that it is produced from an aluminum dross treated in an arc
Steel refining subsidiary materials. 3. The method of claim 2,
Characterized in that the amount of the metallic aluminum contained is 0 wt% or more and 10 wt% or less, and the amount of aluminum oxide contained is 80 wt% or less
Steel refining subsidiary materials.

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