KR20170130564A - Method for reuse of desulfurization slag - Google Patents

Abstract

And to provide a method for reusing desulfurized slag which can reduce a variation in the contribution of desulfurization slag to reuse desulfurization. The molten iron M is desulfurized in the molten iron receiving vessel 6 by using at least a new desulfurizing agent of Lime Seal and a desulfurization slag (hereinafter referred to as " desulfurizing slag " S2 of the desulfurization slag S2 is collected and one or more of the plurality of slag accommodation vessels 5 accommodating the desulfurization slag S2 is selected as a reuse desulfurizing agent and the desulfurization slag S2 contained in the selected slag accommodation vessel 5 from that used as the re-use the desulfurizing agent (S1) in the desulfurization treatment of molten iron after the plurality of slag containment vessel (5), when selecting at least any one as for reuse desulfurizing agent, the holding time is less than the first threshold value T _a, or The slag accommodation vessel 5 and at least one of the slag accommodation vessel 5 and the slag accommodation vessel 5 whose lime usage amount is greater than or equal to the second threshold value X _i are preferentially selected.

Description

METHOD FOR REUSE OF DESULFURIZATION SLAG [0001]

The present invention relates to a method for reusing desulfurization slag, which uses a desulfurization slag generated when a molten iron in a molten iron receiving vessel is desulfurized by a mechanical agitation type desulfurization apparatus using a lime-based desulfurizing agent as a reusable desulfurizing agent in a desulfurization treatment .

In the steel industry, the proportion of steel with extremely low sulfur conten- tions is rising due to recent demand for higher purity and higher performance of steel. Accordingly, in the steelmaking process, a technique for further reducing the steelmaking cost and reducing the amount of slag generated for the low-sulfur steel solvent is required. Generally, sulfur S is included in the molten iron tapped from the blast furnace due to the raw materials used in blast furnaces such as coke. Since sulfur is a component which basically adversely affects the quality of steel, charcoal desulfurization and molten steel desulfurization are performed in accordance with the required quality of steel. Among these, in the charcoal desulfurization, a method of adding a lime-based desulfurizing agent mainly composed of low-cost lime (CaO) to the charcoal, and stirring and mixing is used. The desulfurization reaction in this case proceeds based on the reaction formula shown in "CaO + S? CaS + O".

Recently, resource conservation and energy conservation have been demanded not only for the purpose of reducing manufacturing costs but also in terms of conservation of the global environment, and the desulfurization slag generated in the desulfurization treatment is also reused for the lime-based desulfurizing agent .

For example, Patent Document 1 discloses a method in which a desulfurization slag generated in a desulfurization treatment using a lime-based desulfurizing agent is separated from a molten iron and discharged from the molten iron vessel, the desulfurization slag is charged as a part of the desulfurizing agent onto the molten iron in another molten iron vessel, A method in which desulfurization is carried out by mechanically stirring a molten iron and a desulfurizing agent is proposed.

Also, as a reusing method of the desulfurization slag, a technique of selecting and reusing the desulfurization slag in order to realize a higher desulfurization efficiency with a smaller deviation is also proposed.

For example, Patent Document 2 discloses a method of selecting only a high-temperature and high-concentration desulfurization slag from a desulfurization slag stored in a slag collecting container, sorting the selected desulfurization slag into a new desulfurizing agent (an unused A desulfurizing agent) to the molten iron and mechanically stirring the molten iron.

Further, Patent Document 3, according as the desulfurization slag generated in the desulfurizing process of the molten iron as a part of the lime-based desulfurizing agent re-used in the desulfurization treatment of different molten iron, the slag composition CaO / SiO ₂ is more than 2.5 by mass, Al ₂ O ₃ A method of reusing a desulfurization slag having a content of 10 mass% or less and a sulfur content of 5.0 mass% or less as a desulfurizing agent has been proposed.

Japanese Patent Application Laid-Open No. 2004-76088 Japanese Patent Application Laid-Open No. 2007-262465 Japanese Patent Application Laid-Open No. 2007-262511

However, in the method of Patent Document 1, since the desulfurization slag generated in the processing of various operating conditions is uniformly reused, the contribution of the reused slag to the desulfurization is large, and it is difficult to effectively reduce the new desulfurization agent.

In addition, in the method of Patent Document 2, it has been proposed that slag is removed and reused so as to exclude agglomerated materials such as ground metal and agglomerated materials having a particle size exceeding 50 mm, but in reality, The degree of avoiding massive water was the limit. Therefore, even if complicated operations such as the removal of mass matters are performed, it is insufficient to reduce the deviation of the contribution of the reused slag to desulfurization, and it is difficult to effectively reduce the new desulfurizing agent.

Further, in the method of Patent Document 3, since most of the desulfurized slag is in a solid state, the deviation of the slag composition is large and there is a problem in the representativeness of the slag sample. Therefore, the deviation of the contribution of the reused slag to desulfurization becomes large, and it has been difficult to effectively reduce the new desulfurizing agent.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for reusing desulfurized slag capable of reducing a deviation of contribution of desulfurization slag to reuse. It is also intended to make it possible to reduce the amount of new lime-based desulfurizing agent used and to contribute to reduction of energy consumption for producing lime-based desulfurizing agent which requires more energy for calcining limestone to obtain quicklime .

In order to accomplish the above object, a method of reusing desulfurized slag according to an embodiment of the present invention is a method of reusing desulfurized slag according to an embodiment of the present invention, comprising: a step of desulfurizing a molten iron in a molten iron- The desulfurization slag generated by the desulfurization treatment is withdrawn from the molten iron receiving vessel and recovered, and at least one of the plurality of slag receiving vessels containing the desulfurization slag is selected as a reusable desulfurizing agent, The desulfurization slag accommodated in the storage container is used as a reuse desulfurizer in the subsequent desulfurization treatment of the molten iron and when one or more of the plurality of slag accommodation vessels are selected as the reusable desulfurizing agent, Which is the elapsed time from the time when the slag is accommodated Based on at least one of a retention time corresponding to the slag accommodating container and a used amount of the lime corresponding to each of the plurality of slag accommodating containers which is the used amount of lime in the desulfurizing process in which the desulfurizing slag accommodated in each of the plurality of slag accommodating containers is generated the holding time is the first priority as for the threshold value T _a is shorter than or equal to slag container and lime basic unit is the second threshold value X _i to more or equal slag container of at least one slag containment vessel than re desulfurizing agent .

According to the method for reusing desulfurized slag according to the present invention, the deviation of the contribution of desulfurizing slag to be reused to desulfurization can be reduced, and on the average, new desulfurizing agent can be effectively reduced. Further, it is also possible to reduce the energy consumption required for the production of the lime-based desulfurizing agent.

1 is a schematic view showing a desulfurization treatment facility of a first embodiment of the present invention.
Fig. 2 is a schematic view for explaining a method of desulfurizing molten iron in the first embodiment. Fig.
3 is a flowchart showing a method for recovering desulfurized slag of the first embodiment.
4 is a flowchart showing a method of reusing desulfurized slag of the first embodiment.
5 is a schematic view showing a desulfurization treatment facility of a second embodiment of the present invention.
6 is a flowchart showing a method for recovering desulfurized slag according to the second embodiment.
7 is a schematic view showing a modified example of the desulfurization treatment facility.
8 is a graph showing the desulfurization lime efficiency in the examples.
9 is a graph showing the CaO replacement ratio of the reusable desulfurizing agent in Examples and Comparative Examples.
10 is a graph showing the relationship between the retention time and the CaO replacement ratio due to the difference in unit consumption of lime.

(Mode for carrying out the invention)

≪ First Embodiment >

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as embodiments) will be described in detail with reference to the drawings. In the desulfurization method of molten iron according to the present embodiment, the desulfurization slag generated in the desulfurization treatment by mechanical stirring of the molten iron using the lime-based desulfurizing agent is used again as a raw material of the desulfurizing agent or the sintered ores in the desulfurizing treatment.

As a method for desulfurizing molten iron using a lime-based desulfurizing agent, there are generally employed a desulfurizing agent-entrapping method or a mechanical stirring-type desulfurizing method. In the desulfurizing agent application method, desulfurizing treatment is performed by blowing an inert gas such as argon gas or nitrogen gas into the molten metal together with the carrier gas for the lime-based desulfurizing agent of the powder.

When the desulfurizing slag is reused as a desulfurizing agent in the desulfurizing agent-entrapping method, the recovered desulfurizing slag must be classified and classified. Therefore, when reused, the temperature of the desulfurizing slag is lowered and the heat energy of the desulfurizing slag is recovered I can not. Further, when the desulfurizing slag is reused as the desulfurizing agent in the desulfurizing agent-entrapping method, the step of recovering and regenerating the desulfurizing slag is troublesome, and the cost may be rather high.

On the other hand, in the mechanical stirring type desulfurization method used in the first embodiment of the present invention, the molten iron is mechanically reacted with a refractory material stirrer to react the molten lime added with the lime-based desulfurizing agent added on the bath surface of the molten iron Followed by desulfurization treatment. When the desulfurization slag is reused as the desulfurizing agent in the mechanical stirring type desulfurization method, it is not necessary to crush and classify the recovered desulfurization slag, so that the desulfurization slag can be reused at a high temperature and the thermal energy can be recovered.

[Desulfurization Treatment Plant]

First, with reference to Figs. 1 and 2, a desulfurization treatment equipment according to a first embodiment of the present invention will be described. 1, the desulfurization treatment facility of the first embodiment comprises a charcoal desulfurization treated building 1, a slag receiving vessel beach building 2, and a discharged slag yard 3 .

A molten steel desulfurization treated building 1 is provided with a molten iron discharge field 11, a desulfurization slag entrance port 12, a mechanical agitation type desulfurization device 13 and a slag removal place 14.

The charcoal discharge port 11 is used to discharge the charcoal from the torpedo car 4 that receives and transports the charcoal wire that has been withdrawn from the blast furnace to a hot metal ladle 6 Is a place. In the operation of discharging the charcoal, the charcoal ladle 6 is placed on a hot metal ladle carriage 111, and as the charcoal ladle carriage 111 moves, it moves to the charcoal discharge port 11, And receives the charcoal discharged from the car 4.

The desulfurization slag injection port 12 is a place where the operation of adding the desulfurization slag S2 stored in the slag accommodation vessel 5 as the reusable desulfurization agent S1 to the molten iron held in the hot iron ladle 6 is performed. In the desulfurization slag injection port 12, the desulfurization slag S2 is added to the molten iron ladle 6 by using a heavy machine 121 such as a backhoe.

The mechanical agitation type desulfurization device 13 is a device for desulfurizing the molten iron (M) contained in the molten iron ladle (6). When the molten iron desulfurizing process is performed, the charter ladle 6 is placed on the charter ladle carriage 131, and the charter ladle carriage 131 is moved to the processing position of the mechanical stirring type desulfurizer 13, (M) is subjected to a desulfurization treatment. The mechanical agitation type desulfurization device 13 has a rotating shaft 132, a stirring member 133 and a hood 134 as shown in FIG. The rotating shaft 132 is a member which is held in the vertical direction of FIG. 2 (b), that is, in the vertical direction, and is rotatable around the central axis and is vertically movable. The stirring member 133 is a member of a refractory material, which is also referred to as a stirring blade or an impeller, and is fixed to one end of the lower side of the rotating shaft 132. The hood 134 covers the opening of the upper portion of the chartered ladle 6 and is provided with a rotating shaft 132 passing through the center thereof. Further, the mechanical agitation type desulfurization device 13 has a plurality of addition hoppers (not shown) and a feed chute. A plurality of addition hoppers of the mechanical agitation type desulfurization device 13 are installed above the hood 134 and contain therein materials used for a desulfurization treatment such as a new desulfurizing agent and a desulfurizing additive to be described later. The material accommodated in the addition hopper is cut by a necessary amount as necessary. The charging chute is a chute in which a material to be cut from the addition hopper is added to the interior of the charcoal ladle 6 through an opening (not shown) formed in the hood 134.

The material field 14 is a place where the process of discharging the desulfurization slag S2 from the molten iron ladle desulfurized in the mechanical agitation type desulfurization device 13 is performed. In the manufacturing site 14, as shown in Fig. 2 (c), the desulfurization slag S2 is scraped off by the slag scraper 141 from the tilted heating ladle 6 and discharged. The discharged desulfurized slag S2 is recovered into the slag receiving vessel 5 disposed below the charred ladle 6. The slag receiving container 5 may be a slag pot made of iron or a ladle type container in which refractory is installed.

The slag receiving vessel beach building 2 can store a plurality of slag receiving vessels 5 accommodating the desulfurization slag S2 therein. 1, the slag accommodation vessel beach building 2 is shown as a building different from the chartered desulfurization treated building 1. However, if there is room in the same building as the chartered desulfurized treated building 1, A place for storing a plurality of slag accommodation containers 5 accommodating the desulfurization slag S2 in the same building as the building 1 may be provided.

The discharge yard 3 is a place for discharging and storing the desulfurization slag S2 which is not used as the reusable desulfurizing agent S1 among the desulfurization slag S2 contained in the slag receiving vessel 5. [ The desulfurized slag S3 discharged to the discharge yard 3 can be further returned to other processes in the steelworks or other steelworks to be used as a seam member.

It is also possible to install the molten steel desulfurization treated building 1 in the molten steel desulfurization treated building 1 for handling such as movement or tilting of the molten iron ladle 6 except that the molten iron ladle 6 is placed on the molten iron ladle truck 111, An overhead crane, not shown, is used. Further, in the handling of the slag accommodation container 5, a middle stage, which is not shown, capable of transporting and tilting the slag accommodation container 5 is mainly used.

[Desulfurization Treatment Method]

Next, the desulfurization method of the first embodiment of the present invention will be described with reference to Figs. 1 and 2. Fig.

First, as shown in Fig. 2 (a), a reusable desulfurizing agent S1 contained in a slag accommodation vessel 5 is added to a molten iron M contained in a hot ladle 6 by using a middle stage 121. [ The reusable desulfurizing agent (S1) is a desulfurization slag (S2) generated by the desulfurizing treatment, the details of which will be described later. The molten iron line M is conveyed to a charcoal conveyance container such as the toe dozer 4 as a charcoal line to be discharged from the blast furnace and discharged to the charred ladle 6 from the charred coal discharge port 11. The charcoal M may be desiliconized or dephosphorized prior to being discharged. The denitrification treatment is an oxidation refining treatment performed prior to the tallin treatment, in which oxygen gas such as oxygen gas or iron ore is added to the molten iron M to remove mainly Si from the molten iron. The tallin treatment is an oxidative refining treatment performed after the degreasing treatment, in which an oxygen source such as oxygen gas or iron ore is added to the molten iron M, and a talline flux is added as a tallin flux for absorbing the produced P ₂ O ₅ , Thereby mainly removing P in the charcoal. That is, the molten iron (M) used for the desulfurization treatment may be any component. The molten iron M to be subjected to the desulfurization treatment in the mechanical agitation type desulfurization device 13 is subjected to desulfurization treatment in units of "charge" every one full amount to the charcoal ladle 6.

Subsequently, the molten iron M is subjected to a desulfurizing treatment. First, the molten iron ladle 6 is horizontally moved to a processing position of the mechanical agitation type desulfurizer 13, and then the rotating shaft 132 is lowered to immerse the agitator 133 in the molten iron M. The processing position of the heating ladle 6 is a position where the position on the plane of the rotating shaft 132 is substantially the center of the heating ladle 6. The stirring member 133 is immersed in the molten iron M and then the rotating shaft 132 is rotated to rotate the stirring member 133 and to increase the speed until the predetermined number of revolutions. If the number of revolutions of the stirring body 133 has reached the predetermined number of revolutions, a new desulfurizing agent is cut out from the hopper and put on the molten iron M to be added. The novel desulfurizing agent is a lime-based desulfurizing agent containing CaO, and there is no particular restriction on the content of CaO, provided that CaO is contained and the desulfurizing treatment of the molten iron (M) can be carried out. For example, the novel desulfurizing agent may contain CaO alone or CaO in an amount of 50 mass% or more and, if necessary, other ingredients such as Al ₂ O ₃ , CaF ₂ , MgO, SiO ₂ , And the like are used. As the CaO source of the novel desulfurizing agent, calcium oxide (CaO) can be used. The particle diameter of the novel desulfurizing agent is 1 mm or less or several millimeters or less. In the desulfurization treatment, the desulfurization reaction proceeds by winding the reusable desulfurizing agent (S1) and the new desulfurizing agent on the molten iron (M) being stirred by the agitator (133). Hereinafter, the reusable desulfurizing agent (S1) and the new desulfurizing agent are collectively referred to as a desulfurizing agent. Further, the desulfurizing agent added to the molten iron M becomes the desulfurization slag S2 by the molten iron M or the reaction by heat.

In addition, in order to accelerate the desulfurization reaction during the desulfurization treatment, at the same time as the addition of the new desulfurizing agent, at the timing before or after the addition of the new desulfurizing agent, or during any period during the desulfurization treatment, . Here, the additive for desulfurization refers to an additive for desulfurization which preferentially reacts with oxygen contained in the slag present in or over the molten iron M, thereby reducing the oxygen potential of the molten iron M and slag and promoting the desulfurization reaction . As the additive for desulfurization, aluminum ash is mainly used. The aluminum material is generally a slag generated in the refining process of Al and contains 10 to 50 mass% of metal aluminum and 50 to 90 mass% of Al ₂ O ₃ in view of the effect of accelerating desulfurization and cost of materials Suitable. It is not necessary to separately add the desulfurization additive and the new desulfurizing agent from different hoppers, and the premixed mixture may be added. In order to obtain a high level of desulfurization efficiency, a new desulfurizing agent and an aluminum material are added so that the ratio of "lime / aluminum material", which is the ratio of the amount of lime to the amount of aluminum material in the new desulfurizing agent to be added, Is preferably added.

After the predetermined amount of fresh desulfurizing agent is introduced, the rotating operation of the stirring body 133 continues until a predetermined processing time elapses. After a predetermined time has elapsed, the number of revolutions of the stirring body 133 is reduced, and finally the rotation of the stirring body 133 is stopped. After the rotation of the stirring body 133 is stopped, the rotating shaft 132 and the stirring body 133 are lifted to complete the desulfurization treatment of the molten iron M. [ At this time, the generated desulfurization slag S2 floats, covers the bath surface, and is in a stopped state.

After the desulfurizing treatment is completed, as shown in Fig. 2 (c), the charred ladle 6 containing the charcoal M is transferred to the production site 14, and the desulfurized slag S2 Is discharged, and is recovered into the slag receiving vessel 5.

[Reusing Method of Desulfurization Slag]

Next, a method of reusing the desulfurization slag S2 according to the first embodiment will be described with reference to Figs. 3 and 4. Fig. In the first embodiment, the desulfurization slag S2 generated in the desulfurization treatment is recovered in the slag accommodation vessel 5, and a part of the recovered desulfurization slag S2 is used as a part of the desulfurization agent in the subsequent desulfurization treatment . First, the recovery method of the desulfurization slag S2 will be described.

As shown in Fig. 3, the desulfurization slag S2 is recovered from the leaching ladle 6 after the desulfurization treatment as described above (SlOO) into the slag receiving vessel 5 (S100). The processing shown in Fig. 3 is a processing procedure for recovering the desulfurization slag S2 generated in the single-charge desulfurization processing. In the first embodiment, the process of step S100 is repeated so that the desulfurization slag S2, which is generated in the desulfurization process of the plurality of charcoal lines continuously processed by the mechanical agitation type desulfurization device 13, (5). It is preferable that the slag accommodating vessel 5 is capable of accommodating the desulfurization slag S2 generated in the desulfurizing treatment of the molten iron (M) accounting for 1 to 5 charge, more preferably 2 or 3 charge. It is also preferable to recover the desulfurization slag S2 of a plurality of charges that can be accommodated in the capacity of the slag accommodation vessel 5, from the viewpoint of omitting the transportation of the slag accommodation vessel 5 as far as possible. If the capacity of the slag accommodating container 5 is small, work such as transportation becomes troublesome, which may interfere with smooth operation of the material from the charter receiving container or reusing the desulfurization slag S2. If the capacity of the slag accommodating container 5 is excessively large, the holding time tends to be prolonged, and the desulfurizing slag S2 accommodated in the slag accommodating container 5 is supplied with a desulfurization slag The amount of the desulfurized slag S2 that can be used as the reusable desulfurizing agent S1 tends to decrease in a condition favorable for reducing the amount of the new desulfurizing agent used.

Next, referring to Fig. 4, a method of reusing the recovered desulfurized slag S2 will be described. Firstly, a plurality of slag receiving vessels 5 accommodating the desulfurization slag S2 in the material processing chamber 14 or the slag receiving vessel beach building 2 are connected to a desulfurizing process (S102) based on the amount of lime used in the slag receiving container and the holding time of the desulfurization slag S2, which is the elapsed time since the desulfurizing slag was received in each of the plurality of slag receiving containers.

Here, it is preferable that the amount of lime used is evaluated by a lime basis when the amount of charcoal per each charge is not constant. (1) below, in terms of the amount of lime in the additive such as a novel desulfurizing agent and a reusable desulfurizing agent (S1), added per one ton of molten iron (M) in each desulfurization treatment, . In step S102, when the desulfurization slag S2 contained in the slag accommodating vessel 5 is generated in the desulfurizing treatment with a plurality of charge desulfurizing treatments, Thereby separating the slag accommodating container 5 from each other. Also, in the unit of the lime unit, t represents the charter tone (the mass of the charter line M). B is the amount of new desulfurizing agent added [kg], y is the amount of reusable desulfurizing agent (S1), B is the amount of new desulfurizing agent [ C represents the addition amount of the reusable desulfurizing agent S1 in kg and D represents the mass t of the molten iron M stored in the hot ladle 6. The lime content x of the new desulfurizing agent is a value preset from the specification of the desulfurizing agent, the analysis value, and the like. The replacement ratio y of the reusable desulfurizing agent S1 is a ratio representing the effective amount of the lime as the desulfurizing agent contained in the reusable desulfurizing agent S1 and may be determined in advance from the achievement of the lime efficiency in the desulfurizing treatment using the reusable desulfurizing agent S1 as a part of the desulfurizing agent It is set as an integer or function value. The replacement ratio y of the reusable desulfurizing agent (S1) may be set to a different substitution ratio for each slag receiving vessel (5), depending on the division of the lime basic unit described later.

The holding time corresponding to the slag accommodating container 5 in which the desulfurizing slag S2 is accommodated is the elapsed time since the desulfurizing slag S2 is accommodated in the slag accommodating container 5, When the desulfurization slag S2 is accommodated, the elapsed time from when the desulfurization slag S2 generated in the first charge desulfurization process is received is taken as the elapsed time.

In step S102, a plurality of slag accommodation vessels 5 accommodating the desulfurization slag S2 are set to a first threshold value T of the holding time T (the amount of lime used) based on the holding time corresponding to each slag accommodating container and the lime basic level _a and the second threshold value X _i of the lime basic unit. First division, the per-unit-lime is the second threshold value X _i or more, and the holding time is less than _a first threshold value T the slag container 5 to be divided. In the second division, the slag accommodation container 5 is divided so that the lime basic level is less than the second threshold X _i and the holding time is not more than the first threshold value T _a . First 3 minutes, the retention time of the first threshold value T is exceeded _a slag containment vessel (5) which is divided. For example, the first threshold value T _a is 72 hours and the second threshold value X _i is 7.0 kg / t for the basic unit of lime in the present embodiment.

Then, the one separated in step S102 slag containment vessel (5), the holding time T is less than or equal to _a slag containment vessel in the segment (5) is selected (S104). That is, in step S100, among the slag accommodating containers 5 of the first to third sections, the accommodating containers of the first section and the second section are selected.

Further, at least one of the slag accommodation containers 5 having a large number of slag basic portions among the slag accommodation containers 5 selected at Step S104 is selected as a reusable desulfurizing agent (S106). That is, when both the slag accommodation containers 5 of the first division and the second division are selected in the step S104, in the step S106, any one or more of the slag accommodation containers 5 of the first division, Is selected for this reuse desulfurizing agent. On the other hand, in the case where only one slag accommodation container 5 is selected in step S104, in step S106, any one of the slag accommodation containers 5 in any one of the sections selected in step S104 Or more is selected for reuse desulfurizing agent. In step S106, when the slag accommodating container 5 for reusable desulfurizing agent is selected from the plurality of slag accommodating containers 5 belonging to the same category, the slag accommodating container 5 to be selected is the one of the above- Any one may be preferable, but it is preferable that the amount of the lime is large or the retention time is short.

Thereafter, in step S106, the desulfurization slag S2 contained in the slag accommodation vessel 5 selected as the reuse desulfurizing agent is used as the reusable desulfurization agent S1 (S108). In step S108, the slag accommodation container 5 selected in step S106 is returned to the desulfurization slag inlet 12. The desulfurization slag S2 contained in the slag accommodating vessel 5 is added to the molten iron ladle 6 as a reusable desulfurizing agent S1 in the above-described method using the middle stage 121. [ That is, in the first embodiment, the desulfurization slag S2 which is used as the reusable desulfurization agent S1 and has the holding time T _a or less and the desulfurization slag S2 ) Is preferentially selected and used. After the desulfurization slag S2 accommodated in the slag accommodation container 5 selected as the reuse desulfurizing agent is used as the reuse desulfurizing agent S1, the empty slag accommodation vessel 5 is reused again after the desulfurization- And is used to recover the desulfurization slag S2 discharged from the desulfurization furnace. In order to carry out the subsequent desulfurization treatment of the molten iron, a plurality of slag accommodation vessels 5 containing the desulfurization slag S2 are disposed in the order of steps S102, S104 and S106 shown in Fig. 4, (5) is newly selected.

In the desulfurizing treatment using the reusable desulfurizing agent (S1), as compared with the case where only the new desulfurizing agent is used, the amount of the lime contained in the new desulfurizing agent is increased by multiplying the used amount of the reusable desulfurizing agent and the CaO substitution rate It is possible to reduce it. Here, the value of the CaO replacement rate is set as a reference value in the case where the CaO replacement ratio is the lowest among the reusable desulfurizers corresponding to each division for each division of the slag accommodating container, thereby ensuring the desulfurization treatment to the target value or less In addition, it becomes possible to effectively reduce the amount of the new desulfurizing agent used.

Further, in the method of reusing the desulfurization slag S2, the desulfurization slag S2 contained in the slag accommodation vessel 5 having a longer holding time and becoming the third division is not used for the desulfurization treatment, And is reused as a raw material of the sintered ores. At this time, the slag accommodation vessel 5 of the third division is selected for desulfurization slag discharge and is conveyed to the discharge yard 3. Then, the desulfurized slag S2 contained in the conveyed slag receiving container 5 is discharged to the discharge yard 3. [ The desulfurized slag S3 discharged into the discharge yard 3 undergoes a predetermined process such as cooling and classification to become a raw material for the sintered ores as a quartz member. The desulfurization slag S3 can be effectively used as a source of iron and a heat source at the time of producing the sintered ore in that it contains metallic iron. Here, as the holding time becomes longer, pulverization of the desulfurization slag S2 proceeds, and the desulfurization slag S2 used as the reusable desulfurization agent S1 is liable to be sucked into the exhaust system during the desulfurization process, The desulfurization efficiency tends to decrease. Particularly, in the case of the third division where the holding time becomes longer than T _a , the tendency becomes large. Therefore, in the first embodiment, desulfurization slag S2 of the third division is preferably not used as a reuse desulfurizing agent. The empty slag accommodation container 5 from which the desulfurization slag S2 is discharged is used repeatedly in the process of step S100.

In addition, since there is a limit in the number of the slag accommodating containers 5, when there is no space in the slag accommodating container 5, in order to accommodate the desulfurizing slag S2 generated in the new charcoal desulfurizing process, The desulfurization slag S2 is discharged from a certain slag accommodation vessel 5, is emptied, and is returned to the production site 14. At this time, when there is no slag accommodating container 5 of the third type having _a holding time exceeding Ta, the slag accommodating container 5 of the first or second type is selected for desulfurization slag discharge, An operation of discharging the slag S2 to the material yard 3 is performed. At this time, it is preferable that at least one of the slag accommodating container 5 having a long holding time and the slag accommodating container 5 having a small amount of lime basicity is desirably selected for desulfurization slag discharge.

≪ Second Embodiment >

Next, referring to Fig. 5 and Fig. 6, a method of reusing the desulfurization slag S2 according to the second embodiment of the present invention will be described. As shown in Fig. 5, the desulfurization system of the second embodiment has the same configuration as that of the first embodiment. That is, the desulfurization treatment facility of the second embodiment comprises a chartered desulfurization-treated building 1, a slag receiving vessel beach building 2, and an excavation yard 3. The molten steel desulfurization treated building 1 is provided with a molten iron discharge field 11, a desulfurization slag injection port 12, a mechanical agitation type desulfurization device 13, and a material field 14. In the second embodiment, the desulfurization treatment of the molten iron M is carried out by using the same desulfurization treatment method as that of the first embodiment shown in Fig.

In the method of reusing the desulfurization slag S2 according to the second embodiment, unlike the first embodiment, the desulfurization slag S2 is recovered by the procedure shown in Fig. First, in the second embodiment, the slag receiving vessel 5 for recovering the desulfurized slag S2 generated from the plurality of slag receiving vessels 5 by the desulfurizing treatment of the lime basic level of the second threshold value X _i or more, Two or more slag accommodating containers 5 of the slag accommodating container 5 for recovering the desulfurized slag S2 generated by the desulfurizing treatment of the lime basic level less than the second threshold X _i are selected and classified . As an example of the second threshold value X _i, the basic unit of lime is set to 7.0 kg / t. Then, the desulfurization slag S2 recovered immediately thereafter is referred to with reference to the slag basic unit of the desulfurizing treatment, and from the slag receiving vessel 5 of the classification corresponding to the referenced reference lime level, Are selected as desulfurization slag disposal. In addition, the slag storage container 5 selected as the desulfurization slag recovery is prepared in the production site 14 (S200). The operation in step S200 is performed before the material formation in the material formation site 14 is performed. After the desulfurization process in the mechanical agitation type desulfurization device 13 is completed, or after the lime raw material in the desulfurization process is predicted . In step S200, when preparing the slag receiving container 5 of the classification according to the lime basic level in the production site 14, it is necessary to carry out the slag receiving container 5 of different classification from the production site 14 It may be canceled. In this case, the slag receiving container 5 taken out of the material handling area 14 is transported to the slag receiving container beach building 2 for provisional storage even if there is room in the capacity.

After the step S200, the desulfurization slag S2 is recovered in the slag receiving vessel 5 prepared in the step S200 (S202) from the molten iron ladle 6 after the desulfurizing treatment in the material production site 14. Step S202 is performed in the same manner as step S100. In the second embodiment, the processes of steps S200 to S202 are repeatedly performed, whereby a plurality of charge desulfurization slag S2, which is continuously treated in the mechanical agitation type desulfurization device 13, is supplied to the two types of slag accommodation vessels 5 And collect it. Further, in each slag accommodating container 5, one desulfurization slag S2 that can be accommodated in a charge unit is recovered.

After recovering the desulfurized slag S2 by the above method, the recovered desulfurized slag S2 is used as a raw material for the re-use desulfurizing agent S1 or the sintered ores, in the same manner as in the first embodiment. That is, the same processes as those in steps S102, S104, S106, and S108 shown in Fig. 4 are performed, whereby the desulfurization slag S2 is reused. According to the second embodiment, the desulfurization slag S2 is recovered by dividing the desulfurized slag into two kinds of slag accommodation vessels 5 according to the basic unit of lime of the desulfurization treatment. Therefore, in comparison with the first embodiment, it is possible to increase the rate at which the slag accommodating container 5 having a large number of lime basic portions among the slag accommodating containers 5 accommodating the desulfurizing slag S2 is generated.

Since the number of the slag accommodating containers 5 is limited in the same manner as in the first embodiment, the slag accommodating container 5 for accommodating the desulfurization slag S2 generated in the new charcoal desulfurizing process In the absence of the slag storage container 5, the operation of evacuating the slag accommodation container 5 may be performed even in the slag accommodation container 5 of the first division or the second division. It is also possible to use or discharge the desulfurization slag S2 all together so that the slag containing vessel 5 which is once emptied can be used for the desulfurization slag S2 It may be used as the slag receiving container 5 of the above-mentioned type.

<Modification Example of Embodiment>

While the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to these examples. It will be apparent to those skilled in the art that various changes and modifications can be made without departing from the scope of the invention as defined in the appended claims. Of course, fall within the technical scope of the present invention.

For example, in the above embodiment, in the step S102, the plurality of slag accommodation containers 5 are divided into two basic pieces of lime by using the second threshold X _i . However, the present invention is not limited to this example Do not. For example, the threshold value X _j (j is an integer equal to or more than 1) relating to the lime basic level is added to the second threshold value X _i to divide the plurality of slag accommodating containers 5 into three or more pieces of basic lime It is also good. At this time, the desulfurization slag S2 contained in the slag accommodating container 5 having a large number of lime basic units among the three or more lime basic units is preferentially used as the reuse desulfurizing agent S1.

In the above embodiment, the second threshold X _{i is set} to 7.0 kg / t, but the present invention is not limited to this example. The second threshold value X _i and the threshold value X _j are set so that the CaO substitution rate defined as the mass ratio of the fresh lime content in the new desulfurizing agent equivalent to the amount of the desulfurization slag S2 used as the reusable desulfurizing agent S1, By referring to the relationship of the amount of lime used in the desulfurization treatment in which the desulfurization slag S2 is generated, it is possible to appropriately set the CaO substitution rate so that the CaO substitution rate becomes higher when the amount of used lime is greater than or equal to the threshold value have. Here, the amount of fresh lime in the new desulfurizing agent equivalent to the amount of the desulfurization slag (S2) can be calculated by dividing the desulfurization rate of the molten iron before and after the desulfurization treatment in the case of using a predetermined amount of the desulfurization slag (S2) And comparing the desulfurization rates of molten iron before and after the desulfurization treatment in the case where the amount of use is changed using only the new desulfurizing agent. The relationship between the substitution ratio of CaO and the amount of lime used in the desulfurization treatment in which the desulfurization slag S2 is generated is influenced by the conditions of the desulfurization treatment such as the composition of the additive and the molten iron temperature and the target value of the S concentration of the molten iron after the desulfurization treatment I think. Therefore, it is preferable that the second threshold value X _i and the threshold value X _j are appropriately adjusted according to the conditions of the desulfurizing treatment, and preferably set to a value in the range of 5 kg / t or more and 10 kg / t or less do.

In the above embodiment, in step S102, but that separate the plurality of slag containment vessel (5), using a first threshold value T _a of two limes basic unit, the invention is not limited to this example. For example, the holding time is less than _a first threshold value T may be divided into a plurality of slag containment vessel (5), into a plurality of division using the third threshold value T _j additionally. Further, the third threshold value T _j is _a time shorter than the first threshold value T _a , and one or more threshold values relating to the holding time are further added to add a distinction regarding the holding time of the slag accommodating container 5 Maybe. At this time, in step S104, the slag accommodating container 5 having the short holding time may be preferentially selected. Further, in step S106, the slag accommodating container 5 of different distinction can be selected based on the two parameters of the lime basic level and the holding time, but the slag accommodating container 5 5) is selected can appropriately be selected from the achievements such as the desulfurization efficiency in each division. For example, in step S102, the first threshold value T _a is 72, if the time of the third to the threshold value T _j of 48 hours, a plurality of slag storage container 5, a first division to fifth It may be divided into five segments. At this time, in the first division, the basic unit of lime is 7.0 kg / t or more and the holding time is 48 hours or less. In the second category, the basic unit of lime is 7.0 kg / t or more and the maintenance time is more than 48 hours and less than 72 hours. In the third category, the basic unit of lime is less than 7.0 kg / t and the holding time is less than 48 hours. In the fourth category, the basic unit of lime is less than 7.0 kg / t, and the maintenance time is more than 48 hours and less than 72 hours. In the fifth category, the retention time is more than 72 hours. Then, for example, the slag accommodating container 5 for the reusable desulfurizing agent is firstly selected in order of the first, second, third and fourth sections, and the desulfurized slag S2 accommodated therein is reused Is used as the desulfurizing agent (S1).

In the above embodiment, but the first threshold value T in _a 72 hours, and the invention it is not limited to this example. The first threshold value T _a can be appropriately set based on the value of the holding time at which the desired desulfurization efficiency can not be obtained by differentiating as the holding time becomes longer. The aptitude value of the first threshold value T _a is considered to be influenced by the conditions such as the kind of the additive used, the desulfurization treatment conditions, the capacity of the slag accommodating container 5, and the like. And is preferably set to a value in the range of 48 hours to 72 hours.

In order to effectively reduce the amount of the novel desulfurizing agent by using the reusable desulfurizing agent (S1), it is preferable to increase the CaO replacement ratio of the reusable desulfurizing agent (S1) and increase the amount of the reusable desulfurizing agent (S1). First by with sets the threshold value T _a to an appropriate value, a holding time of only the slag receiving cells of the T _a more than nine minutes selected as for the re-use the desulfurizing agent, but can execute a CaO substitution rate of re-use the desulfurizing agent (S1) to the appropriate range, So that it is preferable not to reduce the target amount of the reusable desulfurization slag S2. For this purpose, the first according to the setting value of the threshold value T _a, by appropriately adjusting the amount of the hot metal 1 charge per re-use the desulfurizing agent (S1) in the desulfurization process, it is preferable to adjust the total amount of re-use the desulfurizing agent (S1) . Accordingly, it is preferable to regulate the average amount of the reusable desulfurizing agent (S1) to be in the range of 50 parts by mass to 150 parts by mass with respect to 100 parts by mass of the average amount of the novel desulfurizing agent.

In the above embodiment, the plurality of slag accommodation vessels 5 are divided into a plurality of sections according to the conditions of the holding time and the basic unit of lime, and the slag accommodation vessel 5 is used for the reuse desulfurizing agent And the desulfurized slag S2 accommodated therein is used in the subsequent desulfurization treatment, the present invention is not limited to this example. For example, a plurality of slag receiving containers (5) can be divided into a plurality of slag receiving containers (5) based on at least one of the holding time of the desulfurized slag (S2) accommodated in the slag receiving container (5) 5) may be selected for reuse desulfurizing agent. At this time, for the holding time of the first the threshold T _a less slag storage container 5 and the lime basic unit is the second threshold value X _i or more slag containment vessel (5) of at least one of a slag containment vessel (5), re-desulfurizing agent .

In the above embodiment, the desulfurization slag S3 discharged from the slag receiving vessel 5 selected for desulfurization slag discharge to the discharge yard 3 is used as a raw material for the sintered ores. However, the present invention is not limited to this example It does not. The desulfurized slag S3 discharged into the discharge yard 3 may be used for a raw material of a cement clinker other than the raw material of the sintered ores.

Further, in the second embodiment, the slag accommodation vessel 5 prepared in the production site 14 may be replaced in accordance with the basic unit of lime in the desulfurization treatment. At this time, the replacement of the slag accommodating container 5 is carried out between the manufacturing site 14 and the slag accommodating container beach building 2 by using a middle stage or the like, but the present invention is not limited to this example. For example, as shown in FIG. 7, a replacement device, not shown, which has a turntable or the like and in which at least two slag accommodating containers 5 can be replaced, may be provided in the molten steel desulfurization- . In this case, a plurality of the classified slag receiving vessels 5 are prepared in the vicinity of the production site 14, and among these, one of the slats corresponding to the basic digestion of the desulfurizing treatment performed in the molten- The slag receiving vessel 5 is prepared in the material stock 14 by the replacing apparatus.

Further, in the above embodiment, the lime basic level is calculated from the lime content included in each new desulfurization and the lime amount effective as the desulfurizer included in the reusable desulfurizer (S1), but the present invention is not limited to this example. For example, when other additives such as dolomite containing lime are used, the lime content is calculated from the lime content contained in all the additives including these additives and the lime amount effective as a desulfurizing agent.

In the above embodiment, the additive is added by the chute. However, the present invention is not limited to this example. For example, an additive may be added by a projection equipment sprayed together with a carrier gas from a lance provided above the heating ladle 6.

In the above embodiment, the desulfurization slag used as the reusable desulfurizing agent (S1) is added to the hot iron ladle (6) in the middle stage (121). However, the present invention is not limited to this example. For example, the desulfurization slag used as the reusable desulfurizing agent (S1) may be added using a feeding device such as a hopper or a chute provided in the mechanical agitation type desulfurizer (13).

In the above embodiment, the slag receiving container 5 containing the desulfurized slag S2 is stored in the slag receiving container beach building 2, but the present invention is not limited to this example. The slag accommodating container 5 in which the desulfurization slag S2 is accommodated may be stored in another place such as the outdoors when a lid or the like is put on a dedicated lid and the lid is not wetted with rain. When the desulfurization slag S2 is wetted with rain or the like, bubbling or dust generation may occur when the desulfurization slag S2 is added to the molten iron M as a reusable desulfurizer.

In the above-described embodiment, the mechanical agitation type desulfurization device 13 is configured to perform the desulfurization treatment, but the present invention is not limited to this example. For example, as a method of performing a desulfurization treatment, an apparatus such as a bubbling type or a gas injection type in which a desulfurization treatment is carried out while taking in and stirring a gas is used, A method of processing molten iron stored in the car 4 or the charter ladle 6 may be selected. As in the case of the above embodiment, the desulfurization slag S2 is recovered from the molten iron receiving vessel and then reused as a raw material for the re-use desulfurizing agent and sintered ores.

In the above embodiment, the plurality of slag accommodation vessels 5 containing the desulfurization slag S2 are divided into a plurality of sections based on the lime basic level and the holding time in step S102. However, Is not limited to this example. For example, a plurality of slag accommodation vessels 5 accommodating the desulfurization slag S2 may be divided into a plurality of sections based on either the lime basic level or the holding time. At this time, after separating the plurality of slag accommodating containers 5, the slag accommodating container 5 of the division satisfying any one of the division of the basic unit of lime and the short division of the holding time is preferentially selected as a reuse desulfurizing agent, It is used in step S108. The lime basicity and the holding time all affect the desulfurization efficiency by the reusable desulfurizing agent (S1). Therefore, by using the above-described constitution, it is possible to reduce the deviations in the contribution of the reusable desulfurizing agent (S1) to desulfurization, compared with the case of not dividing by the basic unit of lime and the holding time.

In the above embodiment, the desulfurization slag S2 is accommodated in the slag accommodating container 5 as long as it can be accommodated in the unit of charge, but the present invention is not limited to this example. For example, when there is a margin in the number of the slag accommodation vessels 5, even if the capacity of the slag accommodation vessel 5 accommodating the desulfurization slag S2 disposed in the production site 14 has room, The container 5 may be classified as an object in step S102. Particularly, this preferred embodiment is a case where the slag accommodating container 5 is preferentially used as a reuse desulfurizing agent in comparison with the other.

In the above embodiment, the desulfurization slag S2 generated in the one-charge desulfurization treatment is recovered in any one of the plurality of slag accommodation vessels 5. However, the present invention is not limited to this example. For example, the desulfurization slag S2 generated in the first desulfurization process may be recovered in a plurality of slag storage vessels 5.

In the step S106 of the above embodiment, one slag accommodation container 5 is selected as the slag accommodation container 5 for reuse desulfurizing agent, but the present invention is not limited to this example. For example, a plurality of slag receiving containers 5 may be selected as the slag receiving container 5 for the re-use desulfurizing agent.

&Lt; Effect of Embodiment >

(1) The method for reusing the desulfurization slag S2 according to the embodiment of the present invention is a method for reusing the desulfurization slag S2 in accordance with the present invention, The desulfurization slag S2 generated by the desulfurization treatment is discharged to the at least one of the vessels 5 from the molten iron receiving vessel 6 and recovered (Step S100), and a plurality of slag accommodated in the desulfurization slag S2 One or more of the desulfurizing slag S2 selected from the container 5 is selected as a reuse desulfurizing agent and the desulfurizing slag S2 contained in the slag receiving vessel 5 selected as the reuse desulfurizing agent is used as a reusable desulfurizing agent S1 And when a plurality of slag accommodating containers 5 are selected from the plurality of slag accommodating containers 5 for use as a reuse desulfurizing agent, a plurality of the slag accommodating containers 5, which is the elapsed time since the desulfurization slag S2 is accommodated, Slag A holding time corresponding to each of the accommodating containers and an amount of lime corresponding to each of the plurality of slag accommodating containers 5 which is the lime usage amount in the desulfurizing process in which the desulfurizing slag S2 accommodated in each of the plurality of slag accommodating containers 5 is generated based on at least one of lime consumption, a holding time of the first threshold value T _a is shorter than or equal to the slag storage container 5 and a lime consumption of the second greater than the threshold value X _i or equal slag containment vessel (5 ) Is preferentially selected as a reuse desulfurizing agent.

Here, the desulfurization reaction proceeds by unreacted CaO. Therefore, if unreacted CaO is not present in the desulfurization slag S2, it does not contribute to the desulfurization reaction. Further, the greater the amount of unreacted CaO in the desulfurized slag, the higher the desulfurizing ability, and the amount of the new desulfurizing agent added when used as the desulfurizing agent can be reduced. However, when the desulfurization slag S2 produced in the various desulfurization processes is recovered and the desulfurization slag S2 is reused as the reusable desulfurization agent S1 without being separated, the desulfurization efficiency of the reusable desulfurization agent S1 is greatly fluctuated do. Therefore, in order to always obtain a favorable desulfurization treatment result in the desulfurization treatment using the reusable desulfurization agent (S1), it is necessary to remove the desulfurization slag (S2), which is produced in the desulfurization treatment with a small amount of lime, It is necessary to carry out the desulfurization treatment on the basis of the case of reusing the exhaust gas S2 and the exhaust gas S2. Therefore, in such a desulfurization treatment, the addition amount of a new desulfurizing agent often increases more than necessary.

On the other hand, according to the above configuration, the desulfurization slag S2, which is contained in the slag accommodation vessel 5 selected based on at least one of the holding time and the amount of the lime used, is used as the reusable desulfurizer S1 Therefore, the deviation of contribution of the reusable desulfurizing agent (S1) to desulfurization can be reduced. Therefore, in the desulfurizing treatment using the reusable desulfurizing agent (S1), the S concentration of the molten iron after the treatment can be controlled to the target concentration range without using the desulfurizing agent excessively. Further, by using at least one of the desulfurization slag having a short elapsed time after discharge from the molten iron receiving vessel and the desulfurization slag generated in the desulfurization treatment of the molten iron having a large amount of lime to be used as a reuse desulfurizing agent, . These effects can reduce the amount of new desulfurizing agent used, which can reduce the cost of producing steel and contribute to the reduction of energy consumption required for the production of lime-based desulfurizing agent. Further, by reducing the amount of the fresh desulfurizing agent used, the amount of desulfurized slag generated in the desulfurizing treatment step can be reduced.

Further, according to the above configuration, since complicated operations such as sampling and analysis of slag are not required as in Patent Document 3, burden on the operator and time required for the treatment can be reduced.

(2) Before selecting any one or more of the slag accommodating containers 5 for reuse desulfurizing agent (steps S104 and S106), a plurality of slag accommodating containers 5 accommodating the desulfurizing slag S2 are divided into a first the division of the holding time based on the threshold values T _a and the second threshold value X _i, which divides into a plurality of separation of at least one of classification by lime usage based on (step S102), a plurality of slag containment vessel (5 ) Is selected as a reuse desulfurizing agent (step S104, 106), the slag receiving vessel 5 for at least one of the short holding time and the large amount of lime is selected as the reusable desulfurizing agent do.

According to the above constitution, as in the case of the constitution (1), the deviation of contribution of the reusable desulfurizing agent (S1) to desulfurization can be reduced, and the amount of the new desulfurizing agent can be reduced.

(3) the time (step S102) to distinguish between a plurality of slag containment vessel (5), the first threshold value T based on _a the separation of the plurality of slag container 5, and re-use the slag receiving container 5 desulfurizing agent time (step S104, 106) selected as the holding time is to select only the first threshold value slag container with the short or the same nine minutes than _a T (5) for re-use as a desulfurizing agent.

According to the above constitution, only the desulfurization slag S2 having a shorter holding time and no influence on the desulfurization efficiency due to the differentiation can be used as the reusable desulfurizing agent S1, so that the deviation of the contribution of the reusable desulfurizing agent S1 to desulfurization It can be further reduced.

(4) A plurality of slag accommodation vessels 5 are further classified based on the second threshold X _i when dividing the plurality of slag accommodation vessels 5 (step S102), and the slag accommodation vessels 5 are reused The slag receiving container 5 having a large amount of lime is preferentially selected as a desulfurizing agent for reuse when it is selected as a desulfurizing agent (steps S104 and 106).

According to the configuration, among the recovered desulfurization slag (S2), since the tendency to starting with a high desulfurization efficiency used in the order, first only separate the slag containment vessel (5) on the basis of the threshold value T _a second threshold value, The addition amount of the novel desulfurizing agent can be reduced as compared with the case where the slag accommodation vessel 5 is not further divided based on X _i .

(5) A plurality of slug accommodating containers 5 are further classified based on a third threshold value T _j that is shorter than the first threshold value T _a when dividing the plurality of slag accommodating containers 5 (step S102) The slag accommodation container 5 having a shorter holding time and a larger amount of lime to be used is selected as the reuse desulfurizing agent in preference when the slag accommodation container 5 is selected as a reuse desulfurizing agent (steps S104 and 106).

(6) A plurality of slag accommodation containers 5 are further classified based on a third threshold value T _j shorter than the first threshold value T _a when dividing the plurality of slag accommodation containers 5 (step S102) When the slag accommodation container 5 is selected as a reuse desulfurizing agent (steps S104 and 106), the slag accommodation vessel 5 having a shorter holding time is preferentially selected as a reuse desulfurizing agent.

According to the constitution (5) or (6), since the slag accommodating container for the reusable desulfurizing agent is selected on the basis of the finer classification than that according to the holding time, the desulfurization slag having higher desulfurization efficiency can be preferentially used. Therefore, the addition amount of the novel desulfurizing agent can be reduced.

(7) The third threshold T _{j is set} to 24 hours or more and 48 hours or less.

According to the above arrangement, when the slag containing vessel 5 containing the desulfurized slag S2 generated by the normal mechanical agitation type desulfurization device 13 is divided based on the holding time, the threshold value T _j is set in the above range The desulfurization performance can be effectively improved in the desulfurization slag S2 accommodated in the slag accommodating vessel 5 in which the retention time is short with respect to T _j and is preferentially selected for reuse desulfurizing agent, Lt; RTI ID = 0.0 &gt; S1) &lt; / RTI &gt; Therefore, the addition amount of the novel desulfurizing agent can be effectively reduced.

(8) the first threshold value T _a, as more than 48 hours, less than 72 hours.

According to the configuration, when classified on the basis of a slag storage container (5) accommodating the desulfurization slag (S2) generated in a typical mechanical agitation type desulfurizing equipment 13 to the holding time, by setting the threshold value T _a in the above-described range, It is possible to effectively reduce the deviation of the desulfurizing ability in the desulfurization slag S2 accommodated in the slag accommodating vessel 5 in which the retention time is short with respect to T _a and is preferentially selected for reuse desulfurizing agent. In particular, since by combining the configuration of the above (3), a holding time of the first threshold value T _a short or slag containment vessel (5) of the same nine minutes than only be selected as for the re-use the desulfurizing agent, the desulfurization of re desulfurizing agent (S1) It is possible to effectively reduce the deviation of the performance and effectively reduce the amount of the new desulfurizing agent added.

The aptitude value of the first threshold value T _a is considered to be influenced by the conditions such as the kind of the additive used, the desulfurization treatment conditions, the capacity of the slag accommodating container 5, and the like. And is preferably set to a value in the range of 48 hours to 72 hours. In addition, when the holding time exceeds 72 hours, there is a high possibility that the desulfurizing ability is lowered due to the influence of the differentiation of the desulfurization slag (S2). If the holding time is less than 48 hours, the adverse effect on the desulfurizing ability by the differentiation is low regardless of the above conditions.

(9) The second threshold X _{i is set} to 5 kg / t or more and 10 kg / t or less.

According to the above arrangement, when the slag containing vessel 5 containing the desulfurized slag S2 generated in the conventional mechanical agitation type desulfurization device 13 is divided based on the amount of used lime, the threshold X _i is set in the above range The desulfurization slag S2 accommodated in the slag accommodating vessel 5 in which the limestone basic unit is selected as the reuse desulfurizing agent with respect to X _i can be effectively improved, Lt; RTI ID = 0.0 &gt; S1) &lt; / RTI &gt; Therefore, the addition amount of the novel desulfurizing agent can be effectively reduced.

(10) A slag accommodating container (5) having a holding time longer than _a first threshold value (Ta) and a slag accommodating container (5) having a used amount of lime less than a second threshold value X _i among a plurality of slag accommodating containers (5) The desulfurized slag S2 contained in the slag receiving container is discharged from at least one slag accommodation container 5 of the vessel 5 and the discharged desulfurized slag S3 is used as a raw material for the sintered ores and the desulfurized slag S2 Is accommodated in the slag accommodating container 5 for accommodating the desulfurized slag S2 discharged from the molten iron receiving vessel 6 again.

According to the above constitution, in the case of using as the reusable desulfurizing agent (S1), it is possible to preferentially use the desulfurization slag (S2) having a low desulfurizing ability as a raw material of the sintered ores. Therefore, the desulfurization slag (S2) It is possible to smoothly perform the operation of preparing the empty slag accommodation vessel 5 and newly receiving the desulfurization slag S2 discharged from the molten iron receiving vessel 6 while preserving the slag.

(11) Before withdrawing the desulfurized slag S2 discharged from the molten iron receiving vessel 6 to any one or more of the plurality of slag receiving vessels 5, a plurality of slag receiving vessels 5 ) Of the desulfurized slag is selected as a desulfurization slag for discharging the desulfurized slag and the desulfurized slag S2 contained in the slag receiving vessel 5 selected for desulfurization slag discharge is discharged from the slag receiving vessel 5, When the desulfurization slag S2 selected as the desulfurization vessel 5 is discharged and the desulfurization slag S2 discharged from the molten iron receiving vessel 6 is recovered to one or more of the plurality of slag receiving vessels 5 after receiving the time a clearing slag using the container 5, as selected for the at least one one desulfurization slag discharged from the slag a plurality of receiving cells (5), the holding time is longer than _a first threshold value T slag A storage container 5 and a slag containment vessel (5) of at least one of lime utilization is less than the second threshold value X _i slag containment vessel (5) is selected in preference for a desulfurization slag discharge.

According to the above configuration, even in the state where there is no space in the slag accommodating container 5, the empty slag accommodating container 5 can be prepared, so that the desulfurizing process can be continued smoothly.

(12) The desulfurized slag (S3) discharged from the slag receiving vessel (5) selected for discharging the desulfurized slag is used as a raw material of the sintered ores.

According to the above configuration, all the desulfurization slag S2 generated in the desulfurization treatment can be reused in the steelworks, so that the blast furnace slag product having a smaller environmental load than the desulfurization slag can be effectively used outside the steelworks.

(13) Before the desulfurization slag S2 discharged from the molten iron receiving vessel 6 is recovered to one or more of the plurality of slag receiving vessels 5 (Step S202), a plurality of slag receiving vessels 5 And when the desulfurization slag S2 discharged from the molten iron receiving vessel 6 is recovered to any one or more of the plurality of slag receiving vessels 5 in the desulfurizing treatment in which the desulfurization slag S2 is generated The slag receiving vessel 5 of the sort corresponding to the amount of lime used in the desulfurizing treatment is selected from the plurality of slag receiving vessels 5 as the desulfurization slag recirculation (Step S200) The desulfurized slag S2 discharged from the molten iron receiving vessel 6 is collected in the slag receiving vessel 5 selected as the receiving vessel.

According to the above arrangement, even when the desulfurizing treatment with different amounts of lime is continuously performed, it can be recovered by dividing it into the corresponding slag receiving vessels 5 for classification of the used amount of lime, so that the slag receiving vessel 5 It is possible to increase the mass ratio of the desulfurization slag S2 accommodated in the desulfurized slag S2. Therefore, since the amount of the reusable desulfurizing agent (S1) having a high replacement ratio of CaO can be increased, the use amount of the novel desulfurizing agent can be further reduced.

(14) The desulfurization slag (S2) generated in the desulfurization treatment of a plurality of charged charcoal is collected in the slag accommodation vessel (5), and the holding time corresponding to the slag accommodation vessel is set to the above- Of the desulfurization slag (S2) of the first desulfurization slag (S2), the amount of the lime corresponding to the slag receiving vessel is set to be the elapsed time after the first desulfurization slag (S2) We use lime usage in charge with low use.

According to the above configuration, since the desulfurization slag S2 of a plurality of charges is recovered to the slag accommodation vessel 5, the time required for the movement of the slag accommodation vessel 5 can be shortened. In this case, the desulfurizing ability of the desulfurized slag S2 contained in the slag receiving vessel 5 is evaluated in an excessive manner, and there is no possibility that desulfurization is insufficient in the desulfurizing treatment of the molten iron.

(15) When the reusable desulfurizing agent (S1) is not used in the desulfurization treatment, the used amount of the quicklime contained in the fresh desulfurizing agent is used, and when the reusable desulfurizing agent (S1) The sum of the amount of quicklime contained in the desulfurizing agent and the amount of the desulfurization slag (S2) used as the reusable desulfurizing agent (S1) multiplied by a predetermined replacement ratio.

According to the above constitution, even in the case of the desulfurization slag (S2) generated in the desulfurization treatment using the new desulfurizing agent and the reusable desulfurizing agent (S1), the desulfurizing ability when reused as the reusable desulfurizing agent (S1) have.

(16) In the desulfurization treatment, the lime / aluminum material as the mass ratio of lime and aluminum material in the novel desulfurizing agent is adjusted to 4.0 to 5.0 using a novel desulfurizing agent, a reusable desulfurizing agent (S1), and an aluminum material .

According to the above arrangement, the amount of aluminum material to be added can be reduced in accordance with the reduction of the amount of the new desulfurizing agent while maintaining the desulfurization efficiency, so that the steel manufacturing cost can be reduced.

Example

Hereinafter, embodiments of the present invention will be described. The molten iron M received from the blast furnace is received by the toffee maker 4 and the molten iron is degassed and tallied in the toffee maker 4 so that the phosphorus concentration of the molten iron M is reduced to 0.07 mass% Respectively. Thereafter, the molten iron M is discharged from the toffed car 4 to the molten iron ladle 6, and in the molten iron ladle 6 containing a dose of about 320 t, (M) was carried out. The molten iron temperature before the desulfurizing treatment was in the range of 1240 캜 to 1320 캜.

In the examples, the desulfurization treatment was carried out using the reusing method of the desulfurization slag S2 of the first embodiment. Specifically, first, the desulfurization slag S2 generated in the desulfurization treatment was recovered (step S100). Then, a plurality of slag storage container 5 is a desulfurization slag (S2) generated in the desulfurizing process contained in each of the two take up to 3 minutes, the molten iron, the first threshold value T _a = 72 hours and the second threshold value X _i = 7.0 kg / t, and divided into three sections of the first to third sections based on the holding time and the amount of used lime (step S102). Here, a total of six slag receiving vessels 5 were used. The procedure of steps S104 to S108 is then carried out so that the desulfurization slag S2 accommodated in the slag accommodation container 5 of the first or the second division selected as the reuse desulfurizing agent S1 is subjected to the subsequent desulfurization treatment And the desulfurized slag S2 contained in the slag accommodation container 5 of the third division was discharged to the discharge yard 3 and used as a raw material for the sintered ores. As a comparative example, the slag accommodating container 5 for reuse desulfurizing agent may be randomly selected without distinguishing the slag accommodating container 5, and the accommodated desulfurizing slag S2 may be used as the reuse desulfurizing agent S1, When the empty slag accommodating container 5 is insufficient, the slag accommodating container 5 for desulfurizing slag discharging is selected at random and the accommodated desulfurizing slag S2 is discharged to the discharging yard 3. In the desulfurization treatment, a new desulfurizing agent and an aluminum material were simultaneously charged at a mass ratio of lime and aluminum in a new desulfurizing agent of 4.0 to 5.0, followed by mechanical stirring for 11 to 15 minutes to complete the desulfurizing treatment . The amount of the reusable desulfurizing agent (S1) added per 1 charge was made from 1600 kg to 3200 kg. When the reusable desulfurizing agent S1 is added, the addition is carried out using the middle stage 121, and the addition amount of 800 kg per bucket of buckets is adjusted to be 2 to 4 buckets per one charge Reuse desulfurizing agent (S1) was added. The added amount of the reusable desulfurizing agent (S1) and the new desulfurizing agent is adjusted in the range of 4.5 kg / t to 9.0 kg / t in accordance with the S concentration of the molten iron before the desulfurization treatment and the target value of the S concentration of the molten iron after the desulfurization treatment did. Here, the lime basic unit is a value calculated by making the replacement ratio y constant at 23 [%] in the above-mentioned formula (1).

8 shows the S concentration (% by mass) before the treatment in the molten iron M in the reusable desulfurizing agent S1 used from the slag receiving container 5 of the first division and the second division as a result of the desulfurization treatment of the embodiment, And the efficiency [%] of desulfurization lime. The desulfurization lime efficiency of the reusable desulfurizing agent S1 is a ratio of the ratio of the basic amount of the lime actually used in the desulfurization reaction to the basic level of the effective limestone in the reusable desulfurizing agent S1 obtained by multiplying the initial amount of the reusable desulfurizing agent S1 by the replacement ratio y , And the results obtained by comparing the results of the desulfurization treatment using the reusable desulfurizing agent (S1) with the new desulfurizing agent and the results of the desulfurization treatment using only the new desulfurizing agent. As a result of the examples, it was confirmed that the desulfurization lime efficiency of the reusable desulfurizing agent (S1) was increased by an average of about 2% as compared with the case of using the reusable desulfurizing agent of the second section by using the reusable desulfurizing agent of the first classification having a large amount of lime.

From the comparison of this result with the desulfurization lime efficiency in the case of using only the fresh desulfurizing agent, the replacement ratio of the reusable desulfurizing agent (S1) used from the slag receiving vessel (5) in each section with a new desulfurizing agent equivalent in desulfurization capacity , Respectively. Fig. 9 shows the calculation results of the average values of the CaO substitution ratios of the reusable desulfurizing agent S1 corresponding to the slag receiving container 5 of the first division and the second division of the embodiment and the reusable desulfurizing agent S1 of the comparative example. As a result of the calculation, it was confirmed that the average CaO replacement ratio was 7% higher in the case of the first division than 23% in the second and comparative examples. That is, in the embodiment, by using the desulfurization slag S2 of the slag accommodation vessel 5 of the first division as the reuse desulfurization agent S1, the average CaO replacement ratio is increased by 7% as compared with the second division or the comparative example And it becomes possible to reduce the amount of new desulfurizing agent used as much as the corresponding amount. This was confirmed to be equivalent to the effect of reducing the fresh lime content of the fresh desulfurizing agent by about 0.15 kg / t in the case of comparing the basic amount of lime with the addition amount of one time of bucket (about 2.5 kg / t). Further, in the case of the comparative example, since the variation of the CaO substitution rate is large, it is necessary to use a lower value of the CaO substitution ratio of the reusable desulfurizing agent (S1), which is a standard when the desulfurization treatment is carried out. Therefore, in the method of reusing the desulfurization slag S2 of the above-described embodiment, the desulfurization slag S2 of the first-stage slag containing vessel 5 having a high CaO replacement ratio is preferentially used, It was confirmed that the desulfurizing ability of the reusable desulfurizing agent (S1) was improved as compared with the case of not recovering the reusable desulfurizing agent (S1).

Further, the inventors of the present invention found that, in the case of using the desulfurization slag S2 in the same manner as in the above-described embodiment and the conditions of the two reuse methods in the case of the comparative example in which the recovered desulfurization slag S2 is not distinguished from the reuse The difference in the basic level of the new desulfurizing agent was investigated. Under each condition, the S concentration in the molten iron (M) before the treatment, the S concentration in the molten iron (M) after the target desulfurization treatment, and the like were subjected to the desulfurization treatment by 20 times with the same treatment conditions. In the case of using the reusing method of the embodiment, the reusable desulfurizing agent (S1) can be reused in such a manner that the reuse desulfurizing agent (S1) from the slag receiving container (5) The CaO substitution rate was changed. On the other hand, in the case of the comparative example in which the desulfurization slag (S2) was not used for reuse, the CaO replacement ratio of the reusable desulfurizing agent (S1) was made constant at the lowest level of CaO replacement rate obtained empirically. In both Examples and Comparative Examples, the amount of the novel desulfurizing agent was reduced in accordance with the product of the amount of the reusable desulfurizing agent (S1) and the substitution ratio of CaO. As a result of the desulfurization treatment, the S concentration in the molten iron (M) after the treatment can be lowered to a target value or less at any charge. Also, in the case of using the re-use method of the embodiment, in the case of the comparative example in which the average freshness of the new desulfurizing agent is 4.2 kg / t and the desulfurization slag S2 is not used for separation, the average freshness of the new desulfurizing agent is 4.9 kg / . From these results, it was confirmed that by using the re-use method of the embodiment, the deviation of the desulfurization efficiency of the reusable desulfurizing agent (S1) was reduced, and the basic level of the new desulfurizing agent was reduced by 0.7 kg / t.

Further, in order to confirm the effect on the desulfurization performance of the holding time, the influence of the holding time on the CaO substitution ratio when the desulfurization slag S2 produced in the desulfurization treatment under the same condition of the lime basicity is used as the reusable desulfurizing agent S1 I investigated. At this time, the condition of the basic unit of lime was set to two conditions of 7.0 kg / t corresponding to the first division of the embodiment and 3.0 kg / t corresponding to the second division of the embodiment. 10 shows the relationship between the holding time when the desulfurization slag S2 is used as the reuse desulfurizing agent S1 and the CaO replacement rate obtained from the result of the desulfurization treatment. Comparing plots within 72 hours of holding time of 7.0 kg / t of lime corresponding to the first division and plots within 72 hours of holding time of 3.0 kg / t of lime per unit corresponding to the second division, It was confirmed that the first section exhibited a high CaO substitution ratio and exhibited a high desulfurization efficiency. Here, these lime basic units are the lowest level of the lime basic unit corresponding to each division, and by setting the CaO replacement ratio corresponding to each division based on Fig. 10, A higher desulfurization efficiency can be obtained and reliable desulfurization up to a target value or less can be achieved. When the holding time was 72 hours or less, it was confirmed that the CaO replacement ratio with respect to the holding time was obtained, and the deviation of the desulfurization efficiency was reduced when reused. On the other hand, when the holding time exceeds 72 hours, the CaO substitution rate is sharply lowered, and it is confirmed that there is a possibility that the deviation of the desulfurization efficiency increases when used.

Further, for example, when the third threshold T _{j is set} to 36 hours and the slag accommodating container 5 of the first and second divisions is further divided based on the holding time, By separately setting the CaO substitution ratios of the reusable desulfurizing agent (S1) corresponding to each classification, it is possible to further reduce the amount of the new desulfurizing agent used. Further, the CaO replacement ratio may be set by a functional formula based on the amount of lime used and the holding time of the slag containing vessel 5 corresponding to the reusable desulfurizing agent S1, and the amount of the fresh desulfurizing agent used may be determined based on this.

From the above results, it was confirmed that the method of reusing the desulfurization slag (S2) according to the present invention makes it possible to reduce the deviation of the contribution of the desulfurization slag to be reused to the desulfurization and effectively reduce the desulfurization agent.

1: Chartered desulfurization treatment building
11: Charter discharge site
111: Charter ladle truck
12: Entry of desulfurization slag
121: Medium
13: Mechanical stirring type desulfurization device
131: Charter ladle truck
132:
133:
134: Hood
14: sanctions
141: slag scraper
2: slag receptacle container beach building
3: Disposal yard
4: Tofidoka
5: slag receiving container
6: Charter ladle
M: Charter
S1: Re-use desulfurizing agent
S2, S3: Desulfurization slag

Claims (16)

At least a desulfurizing agent of the seawater is used to desulfurize the molten iron in the molten iron receiving vessel,
The desulfurization slag generated by the desulfurization treatment is discharged to the at least one of the plurality of slag receiving vessels and recovered from the molten iron receiving vessel,
Wherein at least one of the plurality of slag receiving containers accommodating the desulfurization slag is selected as a reusable desulfurizing agent,
The desulfurization slag contained in the slag receiving vessel selected as a reuse desulfurizing agent is used as a reuse desulfurizing agent in a subsequent desulfurization treatment of the molten iron,
Wherein when at least one of the plurality of slag receiving containers is selected as a reuse desulfurizing agent, the slag receiving container is provided with a plurality of slag receiving containers, Based on at least one of a holding time and a lime usage amount corresponding to each of the plurality of slag receiving vessels which is a used amount of lime in the desulfurizing process in which the desulfurizing slag accommodated in each of the plurality of slag receiving vessels is generated, At least one of the slag receiving containers whose time is shorter than or equal to the first threshold value T _a and at least one of the slag receiving containers whose amount of lime is larger than or equal to the second threshold value X _i is preferentially used as a re- And the desulfurization slag is reused Way. The method according to claim 1,
At least any one from the plurality of slag receiving cells prior to selection as for re-use the desulfurizing agent, the plurality of slag containment vessel that the desulfurization slag accommodated, wherein the first threshold value T _a The division of the holding time based on the and , And a division based on the amount of the lime used based on the second threshold value X _i ,
When selecting at least one of the plurality of slag accommodation vessels for reuse desulfurizing agent, the slag accommodation vessel for at least one of the division of the short holding time and the division of the large amount of lime is selected for the reuse desulfurizing agent Wherein the desulfurization slag is recycled. 3. The method of claim 2,
When distinguish the plurality of slag storage container, and by the first threshold value T based on _a plurality of separate slag containment vessel,
When selecting the slag container as for re-desulfurizing agent, method for reusing the desulfurization slag, characterized in that the holding time is selected as the said first threshold value T _a only the slag container with the short or the same nine minutes reuse desulfurizing agent than . The method of claim 3,
Wherein the plurality of slag accommodation vessels are further divided based on the second threshold value X _i when dividing the plurality of slag accommodation vessels,
Wherein the slag accommodating container having a large amount of lime is preferentially selected as a reusable desulfurizing agent when the slag accommodating container is selected as a reusable desulfurizing agent. 5. The method of claim 4,
When distinguish the plurality of slag storage container, wherein the first threshold value _a shorter than T 3 on the basis of the threshold value T _j separated by adding a plurality of slag storage container,
Wherein the slag accommodating container is selected as a reusable desulfurizing agent in a case where the holding time is short and the amount of the lime is large and the slag receiving container is preferentially used as a reusable desulfurizing agent. The method of claim 3,
When distinguish the plurality of slag storage container, wherein the first threshold value _a shorter than T 3 on the basis of the threshold value T _j separated by adding a plurality of slag storage container,
Wherein the slag accommodating container having a short holding time is preferentially selected as a reusable desulfurizing agent when the slag accommodating container is selected as a reuse desulfurizing agent. The method according to claim 5 or 6,
Wherein the third threshold value T _{j is set} to 24 hours or more and 48 hours or less. 8. The method according to any one of claims 1 to 7,
Method for reusing the desulfurization slag, characterized in that the first threshold value T _a, as more than 48 hours, less than 72 hours. 9. The method according to any one of claims 1 to 8,
Wherein the amount of the lime used is evaluated by a lime basic level in the desulfurization treatment, and the second threshold value X _{i is set} to 5 kg / t or more and 10 kg / t or less. 10. The method according to any one of claims 1 to 9,
Of the plurality of slag containment vessel that the desulfurization slag received, the holding time of the first threshold value T _a longer than slag storage container, and of at least one of the lime amount is the second less slag receiving than the threshold value X _i vessel Discharging the desulfurized slag contained in the slag receiving vessel from the slag receiving vessel,
The discharged desulfurized slag is used as a raw material for sintered ores,
Wherein the slag receiving container in which the desulfurization slag is discharged is used for receiving the desulfurization slag discharged from the molten iron receiving vessel again. 11. The method according to any one of claims 1 to 10,
Before withdrawing the desulfurized slag discharged from the molten iron receiving vessel to any one or more of the plurality of slag receiving vessels, at least one of the plurality of slag receiving vessels containing the desulfurized slag is selected for desulfurization slag discharge and,
Discharging the desulfurized slag received in the slag receiving vessel selected for desulfurizing slag discharging from the slag receiving vessel to empty the slag receiving vessel selected for desulfurizing slag discharging,
Wherein said slag accommodating container is used after being selected for desulfurization slag discharge when recovering said desulfurization slag discharged from said molten iron containing vessel to one or more of said plurality of slag receiving vessels,
At least any one from the plurality of slag container when selected as for the desulfurization slag discharge, is the holding time of the first threshold value T _a longer than slag container and the lime amount and the second is less than the threshold value X _i Characterized in that at least one of the slag receiving vessels is selected as the desulfurizing slag for discharging the desulfurized slag. 12. The method of claim 11,
Wherein the desulfurized slag discharged from the slag receiving vessel selected for discharging the desulfurized slag is used as a raw material for the sintered ores. 13. The method according to any one of claims 1 to 12,
Before the slag containing slag is discharged to the at least one of the plurality of slag receiving containers, the plurality of slag receiving containers are sorted with a lime usage amount,
Containing slag is discharged from the molten iron receiving vessel to the slag receiving vessel, and when the desulfurizing slag discharged from the molten iron receiving vessel is collected in at least one of the plurality of slag receiving vessels, , The slag receiving vessel of the classification corresponding to the amount of the lime used in the desulfurization treatment is selected as the desulfurization slag recovery vessel,
Wherein the desulfurization slag discharged from the molten iron receiving vessel is recovered in the slag receiving vessel selected as the desulfurization slag recovery vessel. 14. The method according to any one of claims 1 to 13,
Withdrawing the desulfurized slag generated in the desulfurization treatment of a plurality of charged charcoal into the slag receiving vessel,
Wherein the holding time corresponding to the slag accommodation vessel is defined as an elapsed time after the desulfurization slag of the first charge occupied among the plural desulfurized slag housed in the slag accommodation vessel,
Wherein the amount of the lime used corresponding to the slag receiving vessel is set as the amount of lime consumed in the case where the amount of the lime used is the smallest among the desulfurization treatments of the plurality of charred lighters. 15. The method according to any one of claims 1 to 14,
The amount of the lime used is measured,
When the reusable desulfurizing agent is not used in the desulfurizing treatment,
Wherein when the reusable desulfurizing agent is used in the desulfurizing treatment, the amount of the quicklime contained in the fresh desulfurizing agent and the amount of the desulfurizing slag used as the reusable desulfurizing agent are multiplied by a predetermined replacement ratio Of the desulfurization slag. 16. The method according to any one of claims 1 to 15,
The lime / aluminum material as the mass ratio of the lime and the aluminum material in the novel desulfurizing agent is adjusted to 4.0 to 5.0 by using the new desulfurizing agent, the reusable desulfurizing agent, and aluminum ash By weight based on the weight of the slag.

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