KR101702247B1 - Refining method and molten steel production method - Google Patents

Abstract

It is an object of the present invention to provide a refining method and a manufacturing method of molten steel for efficiently conducting conversion work even when there is no facility for spraying talline agent in the refining of the converter. A refining method for performing a talline refining or a talline decarburizing refining of a molten iron without injecting a talline agent into a molten iron is carried out by charging a molten iron into the reaction vessel after charging at least a tallane agent containing powder into the reaction vessel And refining is performed.

Description

TECHNICAL FIELD [0001] The present invention relates to a refining method and a manufacturing method of molten steel,

The present invention relates to a refining method of molten iron which performs talline refining or tallin decarburizing refining by causing a talline reaction or a tallin decarburization reaction to be carried out without spraying a tallane agent on a molten metal in a converter, and a method of manufacturing molten steel employing the refining method ≪ / RTI >

In a method of conducting a talline or talline decarburizing refinement of a charcoal in a converter, for example, in the case of considering a CaO-containing tallin as a tallin agent, the talline reaction by the calcium oxide in the converter is expressed by the following formula (1) Lt; / RTI >

3 (CaO) + 5 (FeO) + 2 [P]

= 3 (CaO. P ₂ O ₅ ) + 5 [Fe] (One)

here,

(): Slag component

[]: Component in molten metal

to be.

In this case, it is common to add massive talline CaO to the converter. At this time, in order to improve the talline reaction efficiency, it is necessary that CaO is melted or the FeO level required for P removal is maintained. The melting point of CaO is about 2570 캜, and halogen-based compounds such as fluorite (CaF ₂ ) and alkaline-based compounds have been used as additives for accelerating the melting. However, these compounds are chemically active and have limitations on slag recycling. In addition, for example, fluorocarbons are difficult to be treated by fluorine contained therein, resulting in an increase in the cost of tallin processing.

As a solution, for example, there is a method of spraying a molten metal from a top blow lance in the form of powder (powder) as CaO as a talline agent as described in Patent Documents 1 to 3.

Japanese Patent Application Laid-Open No. 8-311523 Japanese Patent Application Laid-Open No. 2007-224388 Japanese Laid-Open Patent Publication No. 2010-95786

When a method of spraying CaO (talline agent) on the molten iron (molten metal) in the converter type reaction vessel is adopted, equipment for spraying is required.

Further, there is a problem that the particle size and the spraying speed of CaO are restricted when spraying. For example, if the injection speed is excessively slow, it may cause pipe clogging due to calcium oxide powder, poor decarbonization of charcoal, poor talline, and the like. On the other hand, if the injection speed is excessively high, there is a concern about the dust problem due to scattering of the calcium oxide outside the converter. For this reason, it is necessary to determine a range in which the relationship between the particle size of the calcium oxide powder to be used and the jet oxygen velocity to be the carrier gas is optimum in accordance with the condition of the refining facility and so on, and to control it to such an optimum range. However, huge investment is needed to solve these constraints and problems.

As an improvement of the tallin method using spraying, there is a method in which a CaO-containing material is applied (charged) to a converter before charging a molten metal by using it together with injection (see Patent Documents 2 and 3). In this case, however, CaO addition by top blowing is essential.

Further, in the prior art, when the addition of the top blowing CaO is not carried out, the preferable addition conditions of CaO including the preliminary method are not clear, and it has been necessary to develop an effective tallin method.

Here, when refining is carried out without adding the tower-blowing CaO, a method is generally employed in which massive CaO is charged on the molten iron (molten metal) charged in the converter. The reason why the massive CaO is injected is that CaO of the powder is injected into the molten iron (molten metal) when the powder of CaO is injected, and the mixing of CaO and the molten iron becomes insufficient. As described above, when the talline agent is not injected, a massive talline agent is used after removing the tallane agent by the sieve or the like. Conventionally, a preferable method of using CaO as powder has not been established yet.

In general, the massive CaO is pulverized and prepared into a mass of a predetermined particle size by sieve classification. In this massive CaO production process, CaO as a by-product is produced as a by-product. However, there is a problem that CaO in the form of powder can not be effectively used as a talline agent in a plant without a top-blow CaO facility.

It is an object of the present invention to provide a refining method and a manufacturing method of a molten steel for efficiently conducting a converter operation even when there is no equipment for performing tallane spraying in a converter refining have.

The present invention provides, as means for solving the above-mentioned problems, the following.

(1) A method for producing a tallane talline powder, comprising the steps of charging a first tall oil containing a powder having a particle size of 1 mm or less into a reaction vessel, charging a molten iron into a reaction vessel charged with the tallane agent, And a step of carrying out talline or talline decarburization without injecting talline agent into the molten iron.

(2) charging a first tallane agent containing scrap and powder having a particle diameter of 1 mm or less into a reaction vessel, charging a molten iron into the reaction vessel charged with the tallane agent, And a step of carrying out talline or talline decarburization without injecting the talline agent into the molten iron.

(3) The method for refining molten iron according to (1), wherein the first talline agent charged into the reaction vessel has a particle diameter of 90% by mass or more and 5 mm or less.

(4) The method for refining molten iron according to (2), wherein 90% by mass or more of the first talline agent charged into the reaction vessel has a particle diameter of 5 mm or less.

(5) The method for scouring charcoal according to (1) to (4), wherein the ratio of the first tallane to the total of the first and second tallines is 10 to 40 mass%.

(6) The method for scouring charcoal according to (1) to (4), wherein the first tallinn agent contains CaO.

(7) The method for scouring charcoal according to (5), wherein the first talline agent contains CaO.

(8) A method for producing a tallane-containing talline powder, comprising the steps of charging a first tallane agent containing powder having a particle diameter of 1 mm or less into a reaction vessel; charging a molten iron into a reaction vessel charged with the talline agent; And a step of producing molten steel by carrying out talline or talline decarburization without injecting talline agent into the molten iron.

(9) A method for producing a tallane-containing talline powder, comprising the steps of charging a first tall oil agent containing scrap and powder having a particle diameter of 1 mm or less into a reaction vessel; charging a molten iron into the reaction vessel charged with the tallane agent; And a step of producing molten steel by carrying out talline or talline decarburization without injecting the molten steel into the molten steel.

(10) The method for producing molten steel according to (8), wherein the first talline agent has a particle diameter of 90% by mass or more and 5 mm or less.

(11) The method for producing molten steel according to (9), wherein the first talline agent has a particle diameter of 90% by mass or more and 5 mm or less.

(12) The process for producing molten steel as described in (8) to (11), wherein the ratio of the first talline to the total of the first and second tallines is 10 to 40 mass%.

(13) The method for producing molten steel according to (8) to (11), wherein the first talline agent contains CaO.

(14) The method for producing molten steel according to (12), wherein the first talline agent contains CaO.

According to the present invention, it is possible to effectively refine the talline powder by using the talline powder as a talline agent even when there is no spraying facility for the talline agent in the electric furnace refining.

According to the method of the present invention, for example, a method of separately injecting into a converter type reaction vessel in a converter refining can be employed, whereby a calcium oxide powder (talline agent in powder) can be obtained without spraying from a top blow lance Can be used. Further, according to the method of the present invention, it is possible to improve the efficiency when the conventional calcium oxide mass is used as a talline agent, without investing in facilities for a tower blowing facility and without using a halogen-based compound or an alkaline-based compound .

Fig. 1 is an explanatory diagram showing a relationship between a talline amount and a CaO source unit (Example 1).
2 is an explanatory diagram showing the relationship between the amount of talline and the powder CaO conversion ratio (Example 3).

Next, embodiments of the present invention will be described with reference to the drawings.

(About refining method)

In the refining method of the present embodiment, a tallane agent containing powder is charged (charged) into the reaction vessel before the molten iron is charged into the converter type reaction vessel. Thereafter, a charging vessel is charged into the reaction vessel and refining is started. After the charging of the molten iron and before the refining starts or refining, the refining is carried out by appropriately introducing the talline agent into the molten metal.

When refining is carried out by mixing scrap into a molten iron, scrap is first introduced into a converter type reaction vessel, and then a tallane agent containing at least powder is introduced into the reaction vessel. Thereafter, a charging vessel is charged into the reaction vessel and refining is started. After the charging of the molten iron, and before the refining is started or refining, the refining is carried out by appropriately introducing the talline agent.

In addition, for scrap and talline agent to be charged in advance before molten iron charging, talline agent may be charged before scrap. However, it is preferable to load the scrap first, since it is easy to contact the talline agent and the molten iron.

In general, the massive CaO is pulverized and prepared into a mass of a predetermined particle size by sieve classification. In this massive CaO production process, CaO as powder is produced as a byproduct. This by-produced powder (powder) CaO is positively used as a talline agent to be charged before molten iron charging. The powder in this specification refers to a particle diameter of 1 mm or less.

Here, the total amount of the tallane used in the refining is determined based on the analytical value of the molten iron to be refined (the analysis value of molten iron and scrap when scrap is used) and the target P concentration after refining. Then, the amount of the tallane agent to be added in the entire refining process is determined from the determined required removal amount. Further, the amount of talline used in the whole refining can be obtained from the relationship between the amount of talline used and the amount of talline used.

Then, 10% by mass or more of a talline agent (including powder) in the amount of the talline agent to be added in the whole of the determined refining treatment is set as the talline agent to be introduced before the molten iron is input. In addition, the talline agent to be introduced before charging the molten iron is also referred to as a pre-tallane agent.

The remaining tallane agent is charged into the reaction vessel after charging the molten iron. Thereafter, oxygen is blown to start blowing. The injection gas may be Ar, N ₂ , CO, or a mixture thereof. As the remaining talline agent, for example, a mass of 5 to 30 mm or 5 to 50 mm is used. A part of this massive talline agent may be put into the process of blowing.

The above talline agent can use a talline agent containing CaO, but a tallane agent substantially consisting of CaO is more preferable.

In addition, as described above, the tallane agent to be charged in advance before charging the molten iron is preferably 10 mass% or more of the total amount. When it is 10 mass% or less, the effect is small. In addition, if the amount of the talline agent to be charged in advance is too large, the powder may not be mixed with the charcoal, and the powder may be floated or scattered, so that it is preferably 40 mass% or less. And more preferably 15 to 35% by mass, which is a stable effect.

The particle size of the pre-charged talline agent is preferably as fine as possible. However, if it is excessively fine, the crushing cost is added, and there is a problem of oscillation in the handling process, so that it is not necessary to make it finer than necessary. On the other hand, if the particle size is too large, the melting of the tallane agent becomes slow and the dispersion becomes poor, and the slag forming tends to occur during refining. From the above, it is preferable that the talline agent having a particle size of 5 mm or less occupies 90% by mass or more of the pre-charged tallane agent. A talline agent having a particle size of 5 mm or less means that the talline agent of the powder is substantially contained.

(Effects of the present embodiment)

Next, the mechanism of effect manifestation by the refining method in the present embodiment will be described.

The talline effect of CaO as a talline agent on the pulp is better than that of bulk CaO because it is well mixed with charcoal. However, when there is no CaO injection facility, CaO of powder phase is floated only by putting CaO of powder phase into a charcoal line, so that CaO and charcoal are not mixed well and it is difficult to contribute to the reaction, Environment deterioration occurs.

On the other hand, the present inventors have found that when the molten CaO is pre-charged into the converter and the molten iron is added thereto, the mixing effect with the molten iron is effectively expressed. On the basis of this finding, in the present invention, by introducing a tallane agent containing powder before charging the molten iron, the talline effect can be improved without CaO injection.

Here, by preliminarily charging CaO in powder form, the mixed agitation at the time of charging the molten iron is strengthened, and the absorption rate of P (phosphorus) in the slag is improved It accelerates. As a result, it is thought that the total CaO consumption used for refining can be reduced.

Further, in the case of using a CaO injection facility which is a tallin introduction method different from the method of the present invention, and when the talline agent is also introduced by injection, the CaO of the powder is mainly used for injection. Therefore, even when the pre-charging of CaO to the converter is used in combination, the condition of CaO to be pre-charged is not clear.

On the other hand, in the present invention, the above-described effects can be obtained by clarifying the preferable conditions of CaO to be pre-charged under the condition that CaO injection is not performed.

In addition, when the spraying of the talline agent is not carried out, there is an effect that the CaO of powder which has been avoided as a tallane agent can be actively used.

Example 1

(Component C: 3.8 to 4.4% by mass, Si: 0.5 to 3% by mass) after previously charging CaO having a particle size of 98% by mass or less and CaO (powdery CaO) 0.05 to 0.40 mass%, and P: 0.09 to 0.12 mass%) were charged into the converter.

Then, 3 to 5 tons of massive CaO of 5 to 50 mm was charged into the molten iron, and the additive material (light burning dolomite: 1.5 tons) was charged into the molten iron, and the flow rate of the tower blow oxygen was 45 to 60 Nm ³ / t, and bottom blowing oxygen flow rate of 5 to 8 Nm ³ / t. During the blowing, 3 to 8 tons of CaO of 5 to 50 mm was charged on the charcoal, and the resultant was blown for 18 to 25 minutes. The mass ratio (powder CaO transitional ratio) of CaO including the powder charged beforehand to the total amount of CaO at this time is 5 to 23 mass%, the analysis value of steel after refining is 0.025 to 0.045 mass% of C, 0.01% by mass, and P: 0.013% to 0.025% by mass.

The relationship between the total amount of CaO and the amount of talline (? P = charcoal P concentration - charcoal P concentration) used in the above refining is shown by a solid line (?) In FIG.

(Comparative Example 1-1)

Next, CaO (total mass talline agent having a particle size of 5 to 50 mm) of the total amount of CaO was charged into the converter after the charcoal was charged. The refining operation was the same as that of the first embodiment.

The relationship between the total amount of CaO and the amount of talline (? P = charcoal P - charcoal P) used in refining at this time is shown by a dotted line () in Fig.

(Comparative Example 1-2)

The same operation as in Example 1 was carried out except that the massive CaO mass of 5 to 50 mm in all was put in advance before the molten iron was put in place of the CaO containing powder having a particle size of 5 mm or less in Example 1 Respectively.

The result is shown by a one-dot chain line () in Fig.

As shown in Fig. 1, it can be seen that the refining method of Example 1 has a higher amount of talline with respect to the same amount of CaO than the Comparative Example 1-1 and Comparative Example 1-2.

Example 2

Next, 50 tons of scrap were charged into the 330-ton converter, 2 tons of CaO of 95% by mass and less than 5 mm in particle size were charged into the converter, and 280 tons of charcoal was charged to the converter . At this time, the components in the molten iron and scrap total were 3.6% by mass of C, 0.08% by mass of Si and 0.10% by mass of P.

Thereafter, 5 ton of CaO of massive mass of 5 to 50 mm was charged into the molten iron, and the additional raw material (kind of light dolomite: 2 tons) was charged into the molten iron, and the top blow oxygen flow rate of 53 Nm ³ / And the flow rate was 6 Nm ³ / t. During the blowing, 6 tons of CaO: 5 to 50 mm was charged on the molten iron, and the resultant was blown for 22 minutes.

The analysis value of the steel after refining was 0.035 mass% of C, 0.01 mass% of Si, 0.015 mass% of P, and 0.085 mass% of Talline.

(Comparative Example 2-1)

Next, without adding CaO in advance, the total amount of CaO was added in the same manner as in Example 2, and the total amount of CaO (particle diameter: 5 to 50 mm) was added to the converter after scrap and charcoal were charged. The refining operation was the same as in the second embodiment.

In this case, the amount of talline was 0.071 mass%, and the amount of talline was smaller than that of Example 2.

(Comparative Example 2-2)

The same operation as in Example 2-1 was carried out except that CaO powder having a particle diameter of 5 mm or less in Example 2 was preliminarily charged with CaO powder having a particle size of 5 to 50 mm before charging the molten iron.

In this case, the amount of talline was 0.077 mass%, and the amount of talline in the middle between Comparative Example 2 and Example 2 was obtained.

Example 3

In the same operation as in Example 1, the amount of talline when the preliminary amount of CaO was changed was calculated. The results at that time are shown in Fig.

As can be seen from Fig. 2, when CaO exceeds 10%, the amount of talline increases.

Example 4

In the same operation as in Example 1, the flow rate of oxygen in the tower blow was reduced to 22 Nm < ³ > / t, and the tanning time was set to 10 minutes. The temperature of the molten steel was 1400 占 폚, which was lower by about 250 占 폚 than that of the conventional talline decarburization operation, and the steel components after refining were 2 to 4 mass% of C and 0.01 to 0.04 mass% of P. The amount of talline at this time was improved by about 0.01 mass% compared to the amount of talline after refining in the case of not replacing CaO containing powder in the same operation.

Industrial availability

The present invention can be used for a converter that does not have a spraying facility of powder because it can increase the efficiency of talline reaction in a molten metal cuvette without special and enormous facility investment.

Claims (14)

A step of charging a first tallane agent containing powder having a particle diameter of 1 mm or less into a reaction vessel,
Charging a molten iron into the reaction vessel charged with the tallane agent,
Charging a second tallane agent having a particle diameter of 5 to 50 mm into the molten iron after the charging of the molten iron;
And performing talline or talline decarburization without spraying the talline agent into the molten iron. A step of charging a first tallane agent containing scrap and powder having a particle diameter of 1 mm or less into a reaction vessel,
Charging a molten iron into the reaction vessel charged with the tallane agent,
Charging a second tallane agent having a particle diameter of 5 to 50 mm into the molten iron after the charging of the molten iron;
And performing talline or talline decarburization without spraying the talline agent into the molten iron. The method according to claim 1,
Wherein the first talline agent charged into the reaction vessel has a particle diameter of 90% by mass or more and 5 mm or less. 3. The method of claim 2,
Wherein the first talline agent charged into the reaction vessel has a particle diameter of 90% by mass or more and 5 mm or less. 5. The method according to any one of claims 1 to 4,
Wherein the ratio of the first tallane to the total of the first and second tallines is 10 to 40 mass%. 5. The method according to any one of claims 1 to 4,
Wherein the first talline agent contains CaO. 6. The method of claim 5,
Wherein the first talline agent contains CaO. A step of charging a first tallane agent containing powder having a particle diameter of 1 mm or less into a reaction vessel,
Charging a molten iron into the reaction vessel charged with the tallane agent,
Charging a second tallane agent having a particle diameter of 5 to 50 mm into the molten iron after the charging of the molten iron;
And a step of producing molten steel by performing talline or talline decarburization without injecting the molten steel into the molten steel. A step of charging a first tallane agent containing scrap and powder having a particle diameter of 1 mm or less into a reaction vessel,
Charging a molten iron into the reaction vessel charged with the tallane agent,
Charging a second tallane agent having a particle diameter of 5 to 50 mm into the molten iron after the charging of the molten iron;
And a step of producing molten steel by performing talline or talline decarburization without injecting the molten steel into the molten steel. 9. The method of claim 8,
Wherein the first talline agent has a particle diameter of 90% by mass or more and 5 mm or less. 10. The method of claim 9,
Wherein the first talline agent has a particle diameter of 90% by mass or more and 5 mm or less. The method according to any one of claims 8 to 11,
Wherein the ratio of the first tallane to the total of the first and second tallines is 10 to 40 mass%. The method according to any one of claims 8 to 11,
Wherein the first talline agent contains CaO. 13. The method of claim 12,
Wherein the first talline agent contains CaO.

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