JPH11193410A - Molten iron refining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently refine molten iron without generating a problem such as the cost of desulfurizing equipment outside a furnace or reduction in a molten iron temp. by using 2 sets or more of converter-type reactors, desulfurizing the molten iron in at least one set of the reactor and decarburizing the deulfurized molten iron in the other reactors. SOLUTION: The blowing amt. of a molten iron agitating gas for desulfurization processing is preferably made to be >=0.05 Nm<3> /ton per molten iron/min and the supply amt. of oxygen is preferably made to be <=2.5 Nm<3> /ton per molten iron/min. A carbonaceous material such as coke is supplied in the desulfurization processing. A desulfurizing agent and/or the carbonaceous material are appropriately blown in from an agitating gas blowing nozzle of a converter-type reactor. One or more kinds of solid iron sources selected form among reduced iron, a scrap, pig iron, etc., are charged into the converter-type reactor for the desulfurization processing, melted by supplying the oxygen and the carbonaceous material and then, an operating mode is adopted for the desulfurization processing. A stand-by machine during its stopping period can be used for the desulfurization processing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot metal refining method capable of efficiently refining hot metal produced in a blast furnace or a smelting reduction furnace, including desulfurization.

[0002]

2. Description of the Related Art Conventionally, as a method for desulfurizing hot metal produced in a blast furnace or the like, mechanical stirring is carried out by charging lime into a container such as a topid for transferring the produced hot metal to a converter. Out-of-furnace desulfurization methods such as a method (KR method) and a method of injecting lime powder (LI method) are known.

[0003]

However, in such a conventional method, dedicated equipment for performing desulfurization treatment during the transfer of hot metal to the converter yard is required, so that equipment costs are inevitably high. There is a problem. Also, in order to perform desulfurization processing, the freeboard of the container must be enlarged, so the transfer container for hot metal becomes large, the cost of refractory materials used for it increases, and the equipment cost of the container itself also increases . Further, when such desulfurization treatment is performed outside the furnace, the temperature of the hot metal drops, so that the heat margin in the converter decreases, and there is a problem that the amount of scrap that can be consumed in the converter decreases.

[0004] Accordingly, an object of the present invention is to solve the problems of the prior art and efficiently perform hot metal refining including desulfurization without causing problems such as equipment costs and lowering of hot metal temperature. It is to provide a hot metal refining method that can be used.

[0005]

Means for Solving the Problems The present inventors have developed a plurality of reactors based on the idea of using a spare unit of a converter type reaction vessel originally installed for repairing a furnace body brick in a desulfurization process. It was considered that only a desulfurization treatment was performed using a part of the converter type reaction vessel, and the decarburization treatment was performed in another converter type reaction vessel. Here, the converter type reaction vessel includes a side blow type converter, a top side blow type converter and the like in addition to a generally used top and bottom blow type converter.

[0006] The converter type reaction vessel is a large vessel, and has sufficient free board, so that there is no problem in performing desulfurization treatment of hot metal. A large amount of high steelmaking slag or ironmaking slag can be used, thereby enabling efficient desulfurization treatment, and T.S. Since Fe can be reduced at the same time, there is an advantage that the yield is improved.

[0007] Further, since the desulfurization reaction is a reduction reaction, and the introduction of oxygen in the desulfurization treatment is a factor that hinders the desulfurization reaction, it has conventionally been considered that acid transport in the desulfurization treatment should be basically avoided. However, when the desulfurization treatment was carried out in a converter type reaction vessel under strong stirring, it was found that the desulfurization reaction was hardly inhibited even if a certain amount of acid was supplied. Also, the carbon material such as coke contains sulfur, and the supply of carbon material is greatly restricted due to the problem of vulcanization in normal converter operation. In the case of performing desulfurization treatment using carbon dioxide, the step of supplying carbonaceous material is a desulfurization treatment step, and moreover, efficient desulfurization treatment is performed under strong stirring in a converter type reaction vessel, so that carbonaceous material is supplied. It has been found that the vulcanization of hot metal by iron hardly causes any problem, and therefore a relatively large amount of carbon material can be supplied.

[0008] Therefore, in the desulfurization treatment using the converter type reaction vessel, the acid supply and the supply of the carbonaceous material can be relatively easily performed, so that a high temperature treatment advantageous for desulfurization can be performed. Further, it is easy to secure the hot metal temperature in consideration of the hot metal temperature after the treatment and the heat allowance in the post-process, and it is possible to prevent a decrease in [C] in the hot metal by supplying carbonaceous material or the like,
Subsequent decarburization can be carried out extremely advantageously in terms of securing a sufficient heat margin.

Further, in the desulfurization treatment using a converter type reaction vessel, a solid iron source such as scrap can be charged, and by appropriately performing acid supply and carbon material supply, the hot metal temperature after the treatment can be improved. The solid iron source can be efficiently dissolved without any hindrance to the decarburization treatment in the subsequent steps. In addition, since the solid iron source is supplied in the desulfurization treatment step, high-iron reduced iron or the like can be used as the solid iron source without any problem.

[0010] As described above, the usual converter refining equipment has a converter for a converter type reaction vessel for repairing a furnace brick, and this spare machine has a very short furnace brick. Most periods are inactive except for repair periods. Therefore, by using the converter type reaction vessel of such a standby machine for desulfurization treatment of hot metal, desulfurization treatment can be performed without any facility load as in the conventional out-of-furnace desulfurization treatment.

In the hot metal refining method of the present invention, the desulfurization treatment is carried out by utilizing a part of the plurality of converter type reaction vessels (preferably, a converter type reaction vessel of a preliminary machine). It has been found that significant advantages can be obtained both in terms of efficiency and equipment, which have not been seen before, and has the following features.

[1] Hot metal is desulfurized in at least one converter type reactor using two or more converter type reactors, and the hot metal after the desulfurization process is desulfurized in another converter type reactor. A hot metal refining method characterized by obtaining molten steel by charcoal treatment. [2] The hot metal refining method according to the above [1], wherein the injection amount of the hot metal stirring gas in the converter type reactor in the desulfurization treatment is 0.05 Nm ³ / t / min or more per hot metal. Refining method.

[3] In the hot metal refining method according to the above [1] or [2], the amount of acid transported in the converter type reaction vessel in the desulfurization treatment is set to 2.5 Nm ³ / t / min or less per hot metal. Hot metal refining method. [4] The hot metal refining method according to any one of the above [1] to [3], wherein a carbon material is supplied in the desulfurization treatment. [5] The hot metal refining method according to any one of [1] to [4], wherein a desulfurizing material and / or a carbon material is blown from a stirring gas blowing nozzle of a converter type reaction vessel in the desulfurization treatment. Hot metal refining method.

[6] In the hot metal refining method according to any one of the above [1] to [5], a solid iron source is charged together with hot metal into a converter type reaction vessel to be subjected to desulfurization treatment, and acid supply and carbon material supply are performed. And then desulfurizing the solid iron source after dissolving the solid iron source. [7] The hot metal refining method according to any one of the above [1] to [6], wherein steelmaking slag and / or ironmaking slag is charged in the desulfurization treatment.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention uses two or more converter type reaction vessels, desulfurizes hot metal in at least one converter type reaction vessel, and converts the hot metal after the desulfurization processing to another converter type. This is a hot metal refining method in which molten steel is obtained by decarburizing in a reaction vessel. Therefore, in the method of the present invention, there is usually no need to perform the conventional out-of-pile desulfurization treatment, which is conventionally performed, except for special cases such as melting of extremely low sulfur steel.

The desulfurization treatment and the decarburization treatment in the method of the present invention can be carried out using any different converter type reaction vessels. Therefore, a converter type reaction vessel for desulfurization processing and a converter type reactor for decarburization treatment are used. Although it is also possible to provide and carry out each reaction vessel, the most preferred and useful embodiment of the present invention is to use two or more converter type reaction vessels each including a preliminary machine installed in a converter refining facility. It is to carry out desulfurization treatment and decarburization treatment by utilizing.

An ordinary converter refining facility has a plurality (usually two to three) of converter type reaction vessels including a spare machine for repairing a furnace body brick. Generally, one of converter type reaction vessels
The operation period is about 4 to 5 months, and after this operation period, the furnace brick repair period is very short (usually about 2 weeks, and during this furnace brick repair period, the converter type reaction of the spare machine is performed). The container starts operating) and the next operation period starts. Or
In place of the converter type reaction vessel of the standby unit, the standby unit may be put into a stop state as a standby unit. Therefore, for example, in the case of a facility equipped with two converter-type reaction vessels, there is always a converter-type reaction vessel of the standby unit that is in a quiescent state in all periods except the furnace brick repair period. Will be.

Therefore, if the converter type reaction vessel of the standby unit during the idle period is used for desulfurization treatment of hot metal, the equipment can be effectively used without providing a dedicated facility for desulfurization treatment outside the furnace. While performing the desulfurization treatment. For example, during a furnace body brick repair period in the case of equipment having two converter type reaction vessels, whether to perform desulfurization treatment only during this period (in this case, tapping as high S steel is performed) ) Alternatively, by performing a furnace body exchange (preparing a spare furnace body and replacing only the furnace body) with respect to a converter furnace vessel for repairing a furnace body brick, both converter furnaces can be operated. What should I do?

There is no particular limitation on the type of hot metal to which the method of the present invention is applicable, and the method can be applied to refining of hot metal manufactured in a blast furnace or a smelting reduction furnace. It is extremely useful as a hot metal refining method. That is,
Generally, [S] in hot metal produced in a blast furnace is 0.03 wt.
% In the desulfurization process, usually 0.01 wt.
% May be reduced to a level less than%. On the other hand, [S] in the hot metal produced in the smelting reduction furnace is 0.3 to 0.4.
wt%, which is much higher than molten iron in a blast furnace. Therefore, in a conventional desulfurization treatment outside the furnace, it is necessary to reduce such a high level of [S] to a level of less than 0.01 wt%. Is extremely difficult. In this regard, the method of the present invention utilizes the strong stirring of the converter type reaction vessel and performs the desulfurization treatment according to the conditions described below. The desulfurization treatment can be performed without any problem, and the efficient refining of the hot metal can be performed, including the decarburization treatment subsequently performed in another converter type reaction vessel.

[0020] In the present invention method is for performing desulfurization treatment of molten pig iron by using strong agitation function in the converter type reaction vessel, molten iron stirring gas such as N ₂ in this order usually converter type reaction vessel (For example, in the case of a top-bottom blow type converter, a bottom-blown gas) is supplied. The preferable injection amount of the hot metal stirring gas is 0.05 N per hot metal in order to obtain a desired strong stirring action.
m ³ / t / min or more, desirably 0.1 Nm ³ / t / m
in or more. FIG. 1 shows a case where desulfurization treatment was performed in an upper-bottom blow type converter (acid supply amount: 1.0 Nm ³ / t / mi).
Regarding n), the relationship between the blowing amount of the bottom blow gas (nitrogen gas) for hot metal stirring and the desulfurization rate is shown. The desulfurization rate is increased by setting the bottom blow gas amount to 0.05 Nm ³ / t / min or more. Is obtained.

In the desulfurization treatment, acid supply (oxygen supply) through an acid supply lance is performed as necessary. By this acid transfer,
A high-temperature treatment advantageous for desulfurization can be performed, and it is easy to secure the hot metal temperature in consideration of a heat margin in a later step, so that the subsequent decarburization treatment or the like can be advantageously performed. As described above, the desulfurization reaction is a reduction reaction, and the addition of oxygen and oxides in the desulfurization treatment is a factor that hinders the desulfurization reaction. It has been basically thought that it should be avoided. In contrast, the present inventors, when performing desulfurization treatment under strong stirring in a converter type reaction vessel,
It has been found that the desulfurization reaction is hardly inhibited even if a certain amount of acid is supplied.

In consideration of the hot metal temperature after the desulfurization treatment and the heat margin in the post-process, the acid supply is not more than 2.5 Nm ³ / t / min,
Preferably 2Nm ³ / t / min or less, more preferably conducted at a feed rate in the range of less than 1.5Nm ³ / t / min, to thereby advance the and excessive decarburization reaction without desulfurization reaction is inhibited The desulfurization treatment can be performed at a high hot metal temperature without any problem. In addition, when it is not necessary to supply acid from the viewpoint of the processing temperature, the hot metal temperature after the processing, the heat margin in the post-process, and the like, the acid transmission may not be performed.

If the amount of acid supply exceeds 2.5 Nm ³ / t / min, the desulfurization efficiency is reduced due to the inhibition of the desulfurization reaction, and the decarburization reaction proceeds to reduce [C] in the hot metal. However, in the decarburization process that is subsequently performed in another converter type reaction vessel, there is no more heat margin, and problems such as difficulty in dissolving the scrap and adhesion of the metal occur.
FIG. 2 shows the relationship between the amount of acid supply and the desulfurization rate when desulfurization treatment was performed in a top-bottom blow type converter (bottom blown gas amount: 0.1 Nm ³ / t / min). When the amount exceeds 2.5 Nm ³ / t / min, it can be seen that the desulfurization efficiency is extremely deteriorated. In the method of the present invention, since the influence of the acid supply on the desulfurization reaction is small within the above-mentioned supply amount, the supply amount is reduced from the viewpoint of shortening the treatment time by the high-temperature treatment and securing the hot metal temperature after the treatment. It is preferable to carry out the acid feeding within the limit.

In the desulfurization treatment of the present invention, a carbonaceous material such as coke can be supplied as a heat source, and in order to prevent a decrease in [C] in the hot metal due to acid supply. By supplying such a carbon material, it is possible to perform a high-temperature treatment advantageous for desulfurization in combination with the effect of the above-described acid supply, and it is easy to secure the hot metal temperature in consideration of a heat margin in a later process. In addition, it is possible to advantageously carry out the subsequent decarburization treatment or the like while preventing the drop of [C] in the hot metal. The supply amount of the carbonaceous material such as coke is determined in consideration of the acid supply amount and the like according to the target [C] amount in the hot metal after the desulfurization treatment.

In the desulfurization treatment, any desulfurization agent can be added. However, the desulfurization treatment performed in the present invention is substantially equivalent to the treatment time (normally about 15 minutes) of the decarburization treatment performed in another converter type reaction vessel. It is preferable to finish the treatment in about the same time and match it with the operating pitch of the converter that performs the decarburization treatment. Therefore, in order to improve the desulfurization efficiency, lime powder (usually quick lime) is used as necessary. Can be blown from a stirring gas blowing nozzle.

As the desulfurizing agent, one or more of steelmaking slag and ironmaking slag can be charged.
As mentioned earlier, the converter type reaction vessel is a large vessel and has ample free board, so it is possible to use a large amount of highly reactive steelmaking slag and ironmaking slag as a desulfurizing agent, thereby increasing efficiency. Effective desulfurization treatment can be performed.
Further, by using slag as a desulfurizing agent in this way, T.C. Since Fe can be reduced at the same time, the yield is improved. For example, T. When slag of about 5 wt% Fe is used, T.C. Fe can be reduced to about 0.05 wt%. Therefore, when desulfurizing hot metal produced in a smelting reduction furnace, by supplying the smelting reduced slag as a desulfurizing agent, it is possible to improve the efficiency of desulfurization processing of high-sulfur hot metal and improve the yield.

The above-mentioned method of supplying the carbonaceous material and the desulfurizing agent into the converter type reaction vessel may be carried out by an arbitrary method such as gravity drop from the upper part of the furnace using a charging device, or injection (injection) from a stirring gas injection nozzle. Can be adopted,
(1) In the blowing method, a powder having a large specific surface area is used as a carbon material or a desulfurizing agent, so that the reactivity with hot metal can be increased. (2) The energy of the injected powder (carbon material, desulfurizing agent) Strong stirring can be obtained compared to the case where only the stirring gas is blown, and the reaction efficiency can be improved accordingly. (3) The time until the injected carbonaceous material or the powder of the desulfurizing agent floats on the slag Since the gas passes through the metal, the blowing from the stirring gas blowing nozzle is more advantageous in that the reactivity and the stirring property can be increased accordingly. The stirring gas blowing nozzle is, for example, a bottom blowing nozzle in the case of a top-bottom blowing converter, and a carbon material and a desulfurizing agent are blown from the bottom blowing nozzle.

For the purpose of improving the desulfurization efficiency, metal Al or an Al-containing substance, an alloy such as FeSi or SiMn, SiC, or the like can be supplied as a deoxidizing agent after the completion of the acid supply. By further stirring the slag-metal, higher desulfurization efficiency can be obtained. The supply of these deoxidizing agents may be carried out by gravity drop from the upper part of the furnace, but if they are blown from a gas blowing nozzle for stirring, the loss to the slag can be reduced, which is more effective.

Since the desulfurization treatment of the present invention utilizes a converter type reaction vessel, in this desulfurization treatment step, a solid iron source such as scrap can be charged and dissolved. When dissolving the iron source, the supply of heat can be performed by appropriately supplying acid or carbon material, so that it does not adversely affect the hot metal temperature after the treatment or the decarburization treatment in the subsequent step. .

In addition, since the solid iron source is dissolved in the desulfurization treatment, there is no problem even if a solid iron source such as reduced iron having a high sulfur content is charged. The high S reduced iron and pig iron solidified by a cast iron machine before desulfurization can also be used as a solid iron source. Therefore, in the present invention, one or more solid iron sources selected from among reduced iron, scrap, pig iron and the like are charged into a converter type reaction vessel to be subjected to desulfurization treatment, and these are supplied with acid and supplied with carbonaceous material. After the dissolution, an operation mode in which desulfurization treatment is performed can be adopted.

The hot metal desulfurized in at least one converter-type reaction vessel as described above is transferred to another converter-type reaction vessel via a transfer vessel or the like, where it is subjected to decarburization treatment (if necessary). Accordingly, a phosphorus removal treatment is performed at the same time. There is no special restriction on this decarburization treatment, and it may be performed under normal conditions. As the converter type reaction vessel used in the method of the present invention, a top and bottom blown type converter,
A horizontal-blowing converter, a top-blowing converter, etc. may be mentioned. In particular, regarding a converter-type reaction vessel used for desulfurization, a top-bottom-blowing converter is a horizontal-blowing converter or a top-blowing converter. Compared with the converter, the reaction region at the slag-metal interface can be widened, so that the reaction efficiency is good and the desulfurization efficiency can be expected to be improved.

The hot metal refining method of the present invention as described above
There are the following advantages over the conventional method of performing out-of-pile desulfurization treatment. (1) Since the standby unit of the converter-type reaction vessel, which is normally in a quiescent state, can be used as it is for desulfurization, desulfurization is performed without any equipment burden as in conventional out-of-furnace desulfurization be able to. (2) The converter type reactor used for desulfurization has sufficient freeboard, so that a large amount of highly reactive steelmaking slag or ironmaking slag can be used as a desulfurizing agent. Treatment can be performed, and T.D. Since Fe can be reduced at the same time, the yield is improved.

(3) In the desulfurization treatment, acid supply and carbon material supply can be performed using an acid supply lance or the like of the converter type reaction vessel. Conventionally, it has been thought that the supply of oxygen in desulfurization treatment is a factor that hinders the desulfurization reaction, so that acid transport in desulfurization treatment should be basically avoided. , The desulfurization reaction is hardly inhibited even if a certain amount of acid is supplied. Also, the carbon material such as coke contains sulfur, and the supply of the carbon material is greatly restricted due to the problem of vulcanization in a normal converter operation. Since this is a desulfurization treatment step, and efficient desulfurization treatment is performed under strong stirring in a converter type reaction vessel, vulcanization by carbon material supply hardly causes a problem, and therefore a relatively large amount of carbon material is used. Can be supplied. As described above, in the desulfurization treatment using a converter type reaction vessel, the supply of acid and the supply of carbon material can be relatively easily performed, so that a high-temperature treatment advantageous for desulfurization can be performed, and moreover, the heat margin in the post-process is reduced It is easy to secure the hot metal temperature in consideration. Therefore, the amount of scrap charged in the decarburization process can be increased.

(4) Since carbonaceous materials such as coke can be supplied in the desulfurization treatment, it is possible to prevent a decrease in [C] in the hot metal, and therefore to carry out the subsequent decarburization treatment extremely advantageously. In addition, the amount of scrap charged can be greatly increased in combination with the above-described securing of the hot metal temperature. Further, by supplying the carbonaceous material and carburizing the hot metal, a large amount of high-grade generated gas can be obtained in the decarburization process.

(5) Since a desulfurization treatment is performed using a converter type reaction vessel, a solid iron source such as scrap can be charged.
By appropriately performing the above-described acidification and the supply of carbonaceous material, the solid iron source can be dissolved without any hindrance to the hot metal temperature after the treatment and the decarburization treatment in the subsequent step, As a result, the consumption of the solid iron source such as scrap in the entire refining process including the decarburization process can be significantly increased. In addition, since the solid iron source is charged in the desulfurization process, high S reduced iron and pig iron solidified by a cast iron machine before desulfurization were difficult to use in the conventional converter operation. It can be used without problems as a solid iron source.

(6) The hot metal refining method of the present invention is extremely useful especially for refining hot metal produced in a smelting reduction furnace. That is, the [S] in the hot metal produced in the smelting reduction furnace is significantly higher than the hot metal in the blast furnace, and therefore, in the conventional out-of-furnace desulfurization treatment, such a high level of [S] is required. It is difficult to reduce to the level of. On the other hand, in the method of the present invention, a high-S hot metal produced in a smelting reduction furnace by utilizing the strong stirring function of a converter The desulfurization treatment can be performed without any problem, and efficient refining of the hot metal can be performed, including the decarburization treatment that is subsequently performed in another converter type reaction vessel.

The two or more converter type reaction vessels used in the method of the present invention can be used for either desulfurization treatment or decarburization treatment, assuming a normal operation mode in the method of the present invention. Therefore, as a refractory for the converter type reaction vessel, it is preferable to use a MgO-C-based brick having high durability in both desulfurization treatment and decarburization treatment.

[0038]

[Example 1] 100 tons of hot metal was put into a 100-t converter (volume 90 m ³ after bricking), the amount of bottom blown gas was 0.1 Nm ³ / t / min per hot metal, and quick lime was 5 kg / hot metal. t Desulfurization treatment was performed by gravity drop.
In this desulfurization treatment, as shown below, about 1
[S] in hot metal is reduced from 0.032 wt% to 0.01 in 5 minutes
It decreased to 0 wt%. [C] [S] Hot metal temperature Before treatment 4.5 wt% 0.032 wt% 1400 ° C After treatment 4.5 wt% 0.010 wt% 1360 ° C Next, the desulfurized hot metal is decarburized in another converter. , [C]: 0.05 wt%, [S]: 0.010 wt
% Steel was obtained.

Example 2 100 tons of hot metal was put into a 100-t converter (volume after bricking: 90 m ³ ), the amount of bottom blown gas was 0.5 Nm ³ / t / min per hot metal, and quicklime was 5 kg / t per hot metal. A desulfurization treatment was performed by gravity drop. In this desulfurization treatment, as shown below, in about 10 minutes from the start of the treatment, the content of [S] in the hot metal was reduced from 0.032 wt% to 0.1%.
007 wt%. [C] [S] Hot metal temperature Before treatment 4.5 wt% 0.032 wt% 1400 ° C After treatment 4.5 wt% 0.007 wt% 1360 ° C Next, the desulfurized hot metal is decarburized in another converter. , [C]: 0.05 wt%, [S]: 0.007 wt
% Steel was obtained.

[Example 3] [C]: about 3 wt% and [S]: about 0.1 wt% in a 100 t converter (internal volume after bricking: 90 m ³ ).
200 tons of 3 wt% hot metal and the hot metal produced during the manufacturing process [T. Fe]: about 5 wt%, [CaO] / [SiO
₂ ]: Desulfurization treatment with 60 t of slag of 1.2, acid supply from the acid supply lance of 10,000 Nm ³ / h, bottom blown gas amount of 1 Nm ³ / t / min per hot metal, and coke charging amount of 7 t Was carried out. In this desulfurization treatment, as shown below, about 30 minutes after the start of the treatment, [S] in the hot metal was reduced to 0.1.
It decreased from 305 wt% to 0.010 wt%. Further, the hot metal temperature could be raised by 50 ° C. [C] [S] Hot metal temperature Before treatment 3.1 wt% 0.305 wt% 1400 ° C After treatment 4.5 wt% 0.010 wt% 1450 ° C Next, this desulfurized hot metal was processed for 100 tons in another converter.
Decarburization treatment is divided into two each, [C]: 0.05wt
%, [S]: 0.010 wt% of steel was obtained.

Example 4 100 t of hot metal was put into a 100-t converter (volume after bricking: 90 m ³ ), and the amount of bottom blown gas was set to 0.5 Nm ³ / t / min per hot metal. The desulfurization treatment was carried out at a rate of 5 kg / t. In this desulfurization treatment, [S] in the hot metal was reduced to 0.032 wt% in about 5 minutes from the start of the treatment as shown below.
To 0.002 wt%. [C] [S] Hot metal temperature Before treatment 4.5 wt% 0.032 wt% 1400 ° C After treatment 4.5 wt% 0.002 wt% 1380 ° C Next, the desulfurized hot metal is decarburized in another converter. , [C]: 0.05 wt%, [S]: 0.002 wt
% Steel was obtained.

Example 5 100 t of hot metal was put into a 100-t converter (volume 90 m ³ after brick-laying), the bottom blowing gas amount was 0.1 Nm ³ / t / min per hot metal, and quick lime was 5 kg / t per hot metal. , Al was charged at a rate of 0.2 kg / t per hot metal to perform a desulfurization treatment. In this desulfurization treatment, as shown below, [S] in the hot metal was reduced to 0. 5 minutes from the start of the treatment.
It decreased from 032 wt% to 0.002 wt%. [C] [S] Hot metal temperature 4.5 wt% 0.032 wt% at 1380 ° C before treatment 4.5 wt% 0.002 wt% 1400 ° C after the treatment Next, the desulfurized hot metal is decarburized in another converter. , [C]: 0.05 wt%, [S]: 0.002 wt
% Steel was obtained.

Example 6 100 t of hot metal was put into a 100-t converter (volume 90 m ³ after bricking), the amount of bottom blown gas was 0.5 Nm ³ / t / min per hot metal, and quick lime was 5 kg / t per hot metal. , Coke 20kg / hot metal
t was charged, and acid was supplied at 5000 Nm ³ / h from a lance to perform desulfurization treatment. In this desulfurization treatment, [S] in the hot metal was reduced to 0.0 in about 10 minutes from the start of the treatment as shown below.
[C] increased from 3.2 wt% to 4.5 wt% while decreasing from 32 wt% to 0.015 wt%. [C] [S] Hot metal temperature Before treatment 3.2 wt% 0.032 wt% 1380 ° C After treatment 4.5 wt% 0.015 wt% 1400 ° C Next, the desulfurized hot metal is decarburized in another converter. , [C]: 0.05 wt%, [S]: 0.015 wt
% Steel was obtained.

[0044]

According to the hot metal refining method of the present invention described above, desulfurization treatment is performed using at least one converter type reaction vessel, and thereafter, decarburization treatment is performed in another converter type reaction vessel. In order to obtain molten steel by performing
Hot metal refining including desulfurization treatment can be performed efficiently.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the amount of bottom blown gas (N ₂ ) and the desulfurization efficiency when a desulfurization treatment is performed using a top-bottom blow type converter.

FIG. 2 is a graph showing the relationship between the amount of acid transport and the desulfurization efficiency when desulfurization is performed using a top-bottom blow type converter.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Masayuki Watanabe, 1-2-1, Marunouchi, Chiyoda-ku, Tokyo, Japan Nihon Kokan Co., Ltd. (72) Katsuhiro Iwasaki 1-2-1, Marunouchi, Chiyoda-ku, Tokyo, Japan (72) Inventor Susumu Isozaki, 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd.

Claims (7)

[Claims] A hot metal is desulfurized in at least one converter type reactor using two or more converter type reactors, and the hot metal after the desulfurization process is decarbonized in another converter type reactor. A hot metal refining method characterized by obtaining molten steel by processing. 2. The blowing rate of the hot metal stirring gas in the converter type reactor in the desulfurization treatment is set to 0.05 Nm ³ per hot metal.
The hot metal refining method according to claim 1, wherein the hot metal refining method is at least / t / min. 3. The hot metal refining method according to claim 1, wherein the amount of acid fed in the converter type reaction vessel in the desulfurization treatment is 2.5 Nm ³ / t / min or less per hot metal. 4. The hot metal refining method according to claim 1, wherein a carbonaceous material is supplied in the desulfurization treatment. 5. The hot metal refining method according to claim 1, wherein a desulfurizing agent and / or carbon material is blown from a stirring gas blowing nozzle of the converter type reaction vessel in the desulfurization treatment. . 6. A desulfurization treatment is carried out by charging a solid iron source together with hot metal into a converter type reaction vessel to be subjected to a desulfurization treatment, dissolving the solid iron source by supplying acid and carbon material, and then performing a desulfurization treatment. The hot metal refining method according to claim 1, 2, 3, 4, or 5. 7. The steelmaking slag and / or the ironmaking slag is charged in the desulfurization treatment.
The hot metal refining method according to 2, 3, 4, 5 or 6.