CN111712585B

CN111712585B - Foaming and calming method for discharging slag and refining equipment for same

Info

Publication number: CN111712585B
Application number: CN201980012874.XA
Authority: CN
Inventors: 内藤宪一郎; 松泽玲洋; 中切孝夫
Original assignee: Nippon Steel and Sumitomo Metal Corp
Current assignee: Nippon Steel Corp
Priority date: 2018-04-24
Filing date: 2019-04-15
Publication date: 2022-07-26
Anticipated expiration: 2039-04-15
Also published as: JP6935845B2; TW201945550A; WO2019208303A1; JPWO2019208303A1; KR20200105923A; CN111712585A; KR102444944B1

Abstract

The invention provides a foaming and calming method for discharging slag, which is a method for calming the foaming of the discharged slag when slag is discharged from a refining reaction vessel to a slag receiving vessel, wherein the method comprises the following steps: a substance having a viscosity-reducing effect is added as a foaming sedative and is retained on the upper surface layer portion of the slag discharged to the slag receiving vessel.

Description

Foaming and calming method for discharging slag and refining equipment for same

Technical Field

The present invention relates to a method for calming the foaming of discharged slag, that is, a method for calming the foaming of discharged slag when slag is discharged from a refining reactor such as a converter to a slag receiving vessel.

Background

There is a method: after desiliconization or dephosphorization of molten iron in the converter, slag is discharged by tilting the converter to cause a part of slag to flow down from the converter mouth to a slag discharge pot disposed below while keeping molten iron remaining in the converter, and then secondary raw materials such as quicklime (CaO as a main component) are added while the converter is standing upright again, followed by refining.

In this method, slag is easily discharged and the amount of slag discharged is ensured by foaming (frothing) the slag in the converter to increase the apparent volume of the slag. Here, the foaming of the slag is caused by the reaction of carbon (C) in the molten iron and iron oxide (FeO) in the slag to generate carbon monoxide (CO) gas, and the CO gas is retained in the slag.

On the other hand, in the slag pot on the slag receiving side, the foamed slag may overflow beyond the capacity of the slag pot. Since the slag overflow causes problems such as damage to facilities and operational troubles, the tilting speed of the converter, that is, the slag discharge speed, should be lowered while the bubbling in the slag discharge vessel is kept still so that the slag does not overflow. If foaming and calming become a bottleneck and the rate of slag removal has to be reduced, the slag removal time will be prolonged, leading to a reduction in productivity. Further, since the slag in the converter is foamed and solidified during the process, the external appearance volume is reduced, and therefore, the slag discharging property is deteriorated, and the amount of slag introduced in the dephosphorization or decarburization process in the subsequent step is increased, and rephosphorization or splashing (liquid lumps of molten iron or slag are blown out from the mouth of the converter to the outside of the converter) is caused.

Therefore, various methods have been proposed in the past to prevent the foaming slag from overflowing from the slag discharge pot. As the simplest method, there is a method of expanding the capacity of the slag discharge pot. However, there are problems that the capacity of the slag discharge pot is limited to be expanded due to limitations on the space under the converter furnace, the transportation of the slag discharge pot, and the like, and that the equipment investment becomes large when the number of slag discharge pots is large.

Thus,

patent documents

1, 2 and 3 disclose a method of feeding a foaming sedative into a slag extractor to calm and foam. As the foaming sedative material, a material obtained by adding a specific gravity adjusting material (e.g., slag) to a thermally decomposable substance (e.g., pulp residue, organic matter such as plastic, oil such as engine oil, and water) can be used, and the substances constituting the sedative and the mixing ratio thereof, the size, specific gravity, and the method of charging the sedative are defined. These materials are substances that rapidly generate gas by penetrating into the slag after foaming, and therefore, it is considered that the impact of the gas generation thereof contributes to breaking the bubbles, i.e., calming. However, in order to submerge the slag, the slag is often stored in a container or formed into a briquette and then put in the form of a block. Therefore, the reaction interface area may be reduced, the sedative effect may be reduced, or the variation may be increased, and it may not be said that the effect is stably sufficient.

Patent documents

4, 5, and 6 disclose methods of blowing or blowing a carbon material (coke or the like) to calm a bubbling sedative in a refining reaction vessel such as torpedo cars. The carbon material has a low wettability with the slag, and therefore has an effect of breaking a liquid film between bubbles to aggregate and coalesce the bubbles, and is considered to contribute to sedation. On the other hand, however, the carbon material and the iron oxide in the slag react with each other to generate CO gas which causes foaming, and therefore, depending on the conditions, the effect may not be observed.

As a method of calming foaming and splashing, patent document 7 discloses a method of adjusting the viscosity of slag to a predetermined range by adding a viscosity modifier (fluorite or the like) to a converter, and patent document 8 discloses a method of charging an alkali metal and/or an alkaline earth metal compound when desiliconizing while receiving molten iron tapped from a blast furnace. These methods are considered to contribute to sedation by adjusting the viscosity of the slag to facilitate the breaking of bubbles or the floating of bubbles. However, the following problems exist: in order to change the viscosity of the slag, a large amount of a sedative (viscosity modifier) is required, and the viscosity is lowered to promote the movement of substances in the slag, thereby increasing the rate of CO gas generation, and sometimes causing the increase of foaming.

In addition, in all of the methods disclosed in patent documents 4 to 8, a sedative agent is added to a refining reaction vessel. In the refining reactor, the agglomerated molten iron and slag coexist and are stirred more strongly than in the slag-receiving vessel, and therefore, in contrast to the state in the slag-receiving vessel, they cannot be directly used as a foaming and calming means in the slag-receiving vessel. For example, in a refining reaction vessel, the stirring is strong, and therefore, the dispersion of the added sedative agent proceeds rapidly, and the sedation rate is high. On the other hand, since the stirring is performed in a state where the agglomerated molten iron and slag are in contact with each other, even if the addition of the sedative agent is stopped after the sedation is temporarily performed, the situation is greatly different in that the bubbling is again caused by CO gas generated by the reaction between carbon in the molten iron and iron oxide in the slag.

Documents of the prior art

Patent document

Patent document 1 Japanese laid-open patent publication No. 2008-255446

Patent document 2 Japanese laid-open patent publication No. 2009-270178

Patent document 3 Japanese patent laid-open publication No. 2009-287050

Patent document 4 Japanese patent laid-open publication No. 4-180507

Patent document 5 Japanese patent laid-open publication No. 5-287348

Patent document 6 Japanese patent application laid-open No. 9-87719

Patent document 7 Japanese laid-open patent publication No. 62-278213

Patent document 8 Japanese laid-open patent publication No. 2003-147425

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made in view of the problems of the prior art, and has an object to: when slag is discharged from a refining reactor such as a converter to a slag receiving vessel, bubbling of discharged slag is quickly and stably calmed, and overflow of slag from the slag receiving vessel is prevented, whereby problems such as damage to facilities and operational disturbances are avoided, and reduction in productivity and deterioration in slag discharge performance due to reduction in slag discharge speed are prevented, thereby achieving efficient slag discharge.

Means for solving the problems

The present inventors have conducted intensive studies on a method for rapidly and stably calming the foaming of discharged slag when slag is discharged from a refining reactor such as a converter to a slag receiving vessel. As a result, they have found that foaming can be rapidly calmed by adding a substance having a viscosity reducing effect as a foaming sedative and retaining the substance in the upper surface layer portion of the slag discharged into the slag receiving vessel, and have found suitable conditions for carrying out the method, and have completed the present invention. The gist of the present invention is as follows.

(1) A method for calming the foaming of discharged slag when slag is discharged from a refining reaction vessel to a slag receiving vessel,

wherein, the method comprises the following steps:

a substance having a viscosity-reducing effect is added as a foaming sedative and is retained on the upper surface layer portion of the slag discharged to the slag receiving vessel.

(2) The foaming and calming method for discharging slag according to (1), wherein,

as the substance having a viscosity-reducing effect, a compound of an alkali metal, a compound of an alkaline earth metal, or a mixture thereof is used.

(3) The foaming and calming method of discharging slag according to (1) or (2), wherein,

the amount of the substance having a viscosity-reducing effect added is 2kg or more relative to the amount of slag 1t discharged.

(4) The foaming and calming method for discharged slag according to any one of (1) to (3), wherein,

the ratio of substances having a particle size of 10mm or less, which has a viscosity-reducing effect, is 70% by mass or more.

(5) The foaming/calming method for discharging slag according to any one of (1) to (4), wherein,

the height of the viscosity reducing substance is less than 3m from the upper end of the slag receiving container.

(6) The foaming/calming method for discharging slag according to any one of (1) to (4), wherein,

the height of the viscosity reducing substance added is 60% or less based on the height of a table provided on the side surface of the refining reaction vessel from the upper end of the slag receiving vessel.

(7) The foaming/calming method for discharging slag according to any one of (1) to (4), wherein,

when adding substances with a viscosity-reducing effect, a guide with a sliding slope is used.

(8) The foaming and calming method for discharged slag according to any one of (1) to (4), wherein,

when adding substances with viscosity-reducing effect, a guide with a sliding inclined surface is used,

the height of the lower end of the guide piece is less than 3m away from the upper end of the slag receiving container.

(9) The foaming and calming method for discharged slag according to any one of (1) to (4), wherein,

when adding the substances with viscosity-reducing effect, the guide piece with the sliding inclined surface is used,

the height of the lower end of the guide is 60% or less of the height of the upper end of the slag receiving container from a table provided on the side surface of the refining reactor.

(10) The foaming and calming method of discharging slag according to any one of (1) to (9), wherein,

when a substance having a viscosity reducing effect is added, the substance is added while avoiding the vicinity of the slag falling position so that 80 mass% or more of the viscosity reducing substance added is added outside the vicinity of the slag falling position.

(11) The foaming and calming method for discharged slag according to any one of (1) to (4), wherein,

when a substance having a viscosity-reducing effect is added, the viscosity-reducing substance is blown in a direction along the upper surface layer portion by a carrier gas.

(12) A refining facility is provided with:

a refining reaction vessel, and

a slag receiving vessel for discharging molten slag from the refining reactor vessel,

wherein the refining facility further comprises a guide for adding a foaming sedative agent so as to be retained in an upper surface layer portion of the slag discharged to the slag receiving vessel,

the guide has a sliding ramp.

(13) The refining apparatus according to (12), wherein,

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, when slag is discharged from a refining reactor to a slag receiver, the slag bubbles in the discharged slag can be quickly and stably calmed, and the slag can be prevented from overflowing from the slag receiver. Accordingly, it is possible to prevent a reduction in slag discharge speed and to discharge slag at a high speed while avoiding troubles such as damage to facilities and operational disturbances due to the overflowing slag, and thus productivity is improved. Further, since slag removal property is also improved, the amount of slag introduced by dephosphorization or decarburization in the subsequent step can be reduced, and the amount of by-products added and slag generated in the rephosphorization or splash prevention application can be reduced.

Based on the above effects, productivity can be improved, and cost can be reduced (reduction in the amount of used sub-raw materials, reduction in slag generation, suppression of heat loss, and improvement in iron yield).

Drawings

Fig. 1 is a diagram showing a mechanism of calming and foaming by adding a substance having a viscosity-reducing effect so as to stay on an upper surface layer portion of slag.

Fig. 2 is a diagram showing a method of sedation and a refining facility for foaming at the time of slag removal from a converter to a slag removal pot in an example of the embodiment of the present invention.

Fig. 3 is a table showing conditions and results of examples of the present invention and comparative examples.

Description of the symbols

1 bubble

2 foam layer

3 layer of agglomerated slag

4 discharge of liquid film

5 viscosity reducing substance (foaming sedative)

6 very low viscosity region

7 converter (refining reaction vessel)

8 deslagging pot (slag container)

9 molten iron

10 slag of smelting

11 guide member

12 viscosity reducing substance (foaming sedative)

13 very low viscosity region

14 working table

Detailed Description

[ mechanism by which foaming is calmed ]

First, a mechanism of causing sedation and foaming by adding a substance having a viscosity-reducing effect (hereinafter referred to as "viscosity-reducing substance") so as to remain on the upper surface layer portion of slag discharged into a slag-receiving vessel in the present invention will be described with reference to fig. 1.

As shown in fig. 1, the slag after foaming becomes an aggregate of bubbles 1 having a high gas phase fraction (a foam layer 2). In the foam layer 2, the liquid film between the bubbles 1 is discharged and thinned, whereby the bubbles are broken and foaming and calming proceed, but when the viscosity of the liquid film (slag) is high, the discharge rate of the liquid film is slow, and therefore, the foaming and calming rate is reduced. Therefore, it is effective to reduce the viscosity of the slag in order to increase the foaming and calming rate, but it is necessary to add a large amount of a viscosity reducing substance in order to reduce the viscosity of the entire slag.

According to the method of the present invention, when the visbreaking substance 5 is added so as to stay in the upper surface layer portion of the slag after foaming, as shown in fig. 1, a local extremely low viscosity region 6 in which the concentration of the visbreaking substance is high is generated. In this way, in this region 6, the discharge of the liquid film of slag (see arrow 4) is promoted, and the breaking of bubbles rapidly proceeds. Next, the slag of the discharged liquid film is mixed with the liquid film of the bubbles directly below the slag, but since the gas phase fraction is high (the liquid phase fraction is low), the viscosity reducing substance is hardly diluted, and the extremely low viscosity region 6 gradually falls while being maintained. In this way, the extremely low viscosity region 6 gradually falls from the upper layer side of the foamed slag, and the foaming is broken in a chain and quickly. Namely, even if a small amount of a viscosity-reducing substance is added, a sufficient foaming and calming effect is obtained.

In contrast, when the viscosity reducing substance is added to the non-foamed agglomerated slag (agglomerated slag layer 3), the viscosity reducing substance is diluted, and therefore, the extremely low viscosity region cannot be maintained, and the effect is hardly obtained when the viscosity reducing substance is added in a small amount. In addition, when the additive is added to the interior of the slag (foam layer 2) after foaming, although an extremely low viscosity region is generated, the calming effect does not act on the upper side, and therefore, the effect is limited as compared with the case of adding the additive so as to stay in the upper surface layer portion. That is, when the viscosity reducing substance is added, it is important to prevent the viscosity reducing substance from being added so as to be entrapped in the inside of the non-foamed agglomerated slag or the foamed slag and to be retained in the upper surface layer portion.

[ reason for applying foaming and calming in a vessel receiving slag ]

Further, the reason why the method of the present invention is applied to foaming and calming in a slag receiving vessel will be described from the difference in foaming state between the inside of a refining reaction vessel such as a converter and the inside of a slag receiving vessel such as a slag discharge vessel.

First, the stirring in the slag receiving vessel is weaker than that in the refining reactor. In the case of a refining reactor, since stirring is strong, even if the viscosity reducing substance is added so as to stay in the upper surface layer portion of the slag, the viscosity reducing substance is diluted or intrudes into the foamed slag due to stirring, and it is difficult to exhibit the effect. On the other hand, in the case of the slag receiver, since stirring is weak, if the method of adding the viscosity reducing substance is appropriately adjusted, it is relatively easy to cause the viscosity reducing substance to stay in the upper surface layer portion of the slag.

Next, a large amount of agglomerated molten iron is present in the refining reactor, whereas only the granular iron mixed into the slag is present in the slag receiver, and no agglomerated molten iron is present. In the case of a refining reactor, since the molten iron and the slag in the form of lumps come into contact with each other, even if the bubbles are temporarily calmed, the bubbles are generated again by CO gas generated by the reaction between carbon in the molten iron and iron oxide in the slag. Therefore, in order to prevent the occurrence of foaming, the viscosity of the entire slag needs to be reduced to a region where foaming does not occur, and a large amount of viscosity reducing material is required. On the other hand, in the slag receiving vessel, since the foaming does not occur again even if the foaming is calmed down, it is effective to add a small amount of the viscosity reducing substance so as to remain on the upper surface layer portion of the slag.

[ embodiment ]

Based on the above mechanism, an embodiment of the present invention will be described with reference to fig. 2. As shown in fig. 2, a converter 7 is taken as an example of the refining reactor, and a slag receiving vessel is taken as an example of a slag discharge pot 8 used for removing slag from the converter 7.

(viscosity-reducing substance)

First, as the viscosity-reducing substance 12 used as a sedative, it is desirable to use a compound of an alkali metal or a compound of an alkaline earth metal, or a mixture thereof.

The reason for this is that the slag which is liable to foam contains a large amount of SiO ₂ An acidic oxide is included, but in molten slag, the acidic oxide forms a network structure and has an effect of increasing viscosity; on the other hand, the alkali metal compound and the alkaline earth metal compound have a function of cutting the network structure, and the viscosity is lowered.

Specific examples of the alkali metal compound and the alkaline earth metal compound include CaF ₂ 、CaCO ₃ 、CaO、Ca(OH) ₂ 、Na ₂ CO ₃ 、K ₂ CO ₃ And the like.

In addition, when the viscosity-reducing substance 12 used as a sedative is a fluoride or oxide of an alkali metal or alkaline earth metal, it is more preferable from the viewpoint of sedative foaming because gas is not generated at high temperature. In the above specific example, CaF ₂ CaO corresponds to this.

When the viscosity-reducing substance 12 used as a sedative is a carbonate or hydroxide of an alkali metal or alkaline earth metal, gas is generated at high temperature. In the above embodiment, CaCO ₃ 、Ca(OH) ₂ 、Na ₂ CO ₃ 、K ₂ CO ₃ In accordance therewith.

Hereinafter, the method of adding the viscosity-reducing substance used as a sedative, the amount of the viscosity-reducing substance added, and the conditions for the properties will be described in detail.

First, in order to retain the visbreaking substances in the upper surface portion of the slag, it is important to reduce the velocity in the vertical direction at the time when the visbreaking substances reach the upper surface portion of the slag.

(height of addition of viscosity-reducing substance)

For this reason, it is desirable to add the viscosity-reducing substance from a low position. Specifically, the height of the viscosity reducing agent added is preferably 3m or less, more preferably 2m or less from the upper end of the slag removing pot.

The table 14 is usually provided on the side surface of the converter, and the height of (the upper surface of) the table 14 is about 5m from the upper end of the slag discharge pot. The height of the viscosity reducing substance to be added is set based on the table 14, and when the height of the table 14 from the upper end of the slag removing pot is set to 100%, the height is preferably 60% or less (height from the upper end of the slag removing pot), and more preferably 40% or less.

(means for adding)

As a device for addition, a guide having a sliding slope (i.e., a member having a function of sliding down an article, a chute (cut)), such as a chute (setter) or a pipe (pipe), may also be used. Added by falling naturally through the guide. By sliding the viscosity reducing substance on the sliding slope, the velocity of the viscosity reducing substance in the vertical direction at the lower end of the guide (the height at which the viscosity reducing substance is added) can be reduced. From the viewpoint of reducing the velocity of the viscosity reducing substance in the vertical direction, the angle of the guide at the lower end of the guide (i.e., the angle with respect to the horizontal direction defining the velocity direction of the viscosity reducing substance at the lower end of the guide) is preferably 30 ° or less.

The guide 11 of the present embodiment will be described in detail with reference to fig. 2. The guide 11 of the present embodiment is provided below the table 14, and both the lower end and the upper end of the guide 11 are located below the table 14. In addition, the slope of the guide 11 (the average slope of the slope on which the viscosity reducing substance slides) is less than 45 degrees, specifically less than 30 degrees, with respect to the horizontal direction. The height of the lower end of the guide 11 (the height to which the viscosity reducing agent is added) is set to be within 3m, specifically, within 2m from the upper end of the slag pot 8. In addition, the height of the table 14 from the upper end of the slag discharging pot (5 m in this example) is set to 100% and the height of the lower end of the guide 11 is set to 60% or less, specifically 40% or less, with respect to the table 14.

In order to uniformly add the anti-adhesion agent to the upper surface layer of the slag, the guide may be movable or rotatable, or a plurality of guides may be used, or particles of the anti-adhesion agent may be carried by a carrier gas and sprayed onto the upper surface layer.

The method of blowing the viscosity reducing substance to the upper surface layer portion with the carrier gas is a method of blowing the viscosity reducing substance in a direction along the upper surface layer portion (a direction close to a horizontal direction) using a hose or the like. According to this method, the velocity in the vertical direction at the time when the viscosity reducing substance reaches the slag upper surface portion can be easily reduced, and the viscosity reducing substance can be effectively retained in the slag upper surface portion.

(relationship with the vicinity of the position where the slag falls)

In addition, in the slag receiving container, the vicinity of the slag falling position is locally strongly stirred by the energy of the slag falling position. Therefore, when the viscosity reducing substance is added in the vicinity of the slag falling position, the viscosity reducing substance added in the vicinity of the slag falling position is less likely to remain on the slag upper surface portion.

Therefore, it is desirable to avoid the vicinity of the slag falling position and add the slag. But is not intended to exclude the case where a part of the added visbreaking substances is added to the vicinity of the slag-dropping position. That is, it is preferable to add 80 mass% or more, more preferably 95 mass% or more of the visbreaking material added to the slag falling position by avoiding the vicinity of the slag falling position.

Here, the vicinity of the slag falling position is the inside of a virtual circle on the slag upper layer surface centered on the center of the portion where the slag upper layer surface in the slag container collides with the slag falling flow. The diameter of the virtual circle varies depending on the position energy of the slag falling, and therefore cannot be considered in a short time, but in the case of a facility having a length of 5 to 10m from the lower end of the mouth of a tilting converter (see fig. 2) to the upper end of the slagging boiler, a range of 1 to 2m is targeted.

As the timing of adding the viscosity reducing substance, for example, the slag level height at which the addition of the viscosity reducing substance is started and the slag level height at which the addition is stopped are previously defined as targets, and the addition of the viscosity reducing substance may be started or stopped when the slag level reaches each of the predetermined heights while monitoring the slag level in the slag receiving vessel, and these operations may be intermittently repeated.

(amount added)

Next, it has been found that when the amount of the viscosity reducing substance added is less than 2kg relative to the amount of slag 1t discharged, a sufficient sedative effect cannot be obtained, and it is preferable to set the amount to 2kg or more.

The optimum amount of addition within the above range varies depending on the capacity of the slag receiver, slag composition, temperature, foaming condition, and the like, but it is preferable to previously examine an appropriate amount of addition within a range of normal operating conditions by a preliminary test.

(Property: particle size)

Further, regarding the particle size of the viscosity reducing substance, if the particle size is large, the viscosity reducing substance tends to intrude into the inside and not to stay on the upper surface layer portion of the foaming slag, and further, time is required for melting, and there is a problem that the formation of the extremely low viscosity region is slow. Therefore, as a result of investigation, the sedative effect is high in the range of particle size of 10mm or less, and it is not always necessary that all particle sizes are in the above range, and a sufficient effect can be obtained if the ratio of particle sizes including the above range is 70 mass% or more. The lower limit of the particle size is not particularly limited, but if the particle size is too small, scattering to the outside of the slag receiver due to an ascending gas flow or gas generated from the slag in the slag receiver increases, and therefore, it is preferably determined in consideration of these.

The particle size is defined as the mesh size of a sieve through which particles can pass, and a particle size of 10mm or less means that a sieve of 10mm can pass.

In the above description, the embodiments of the present invention are explained assuming that a converter is used as a refining reactor and a slag discharge vessel used for discharging slag from the converter is used as a slag receiving vessel. However, the application object of the present invention is not limited to these vessels, and the present invention can be applied to the case where slag is discharged from another refining reaction vessel (for example, torpedo car) to another slag receiving vessel (for example, a slag discharge vessel).

In addition, when the entire amount of the necessary sedative cannot be added by the method of the present invention due to the limitation of the facilities and operations, a corresponding effect can be obtained by adding a part of the sedative by the method of the present invention and adding the remaining sedative by the same method as the conventional method.

In the above description, the specific guide 11 is described with reference to fig. 2, but the guide of the present invention is not limited thereto. For example, the upper end of the guide may be located above the table, or may be formed as a guide whose angle changes stepwise or continuously by a meandering tube or the like.

Examples

Hereinafter, examples of the present invention (hereinafter, referred to as examples) and comparative examples will be described.

The conditions of the examples are examples of conditions employed for confirming the feasibility and effects of the present invention, and the present invention is not limited to the examples. Various conditions may be adopted within the range to achieve the object of the present invention without departing from the gist of the present invention.

(common conditions)

The test was carried out in a 350 t-scale top-and-bottom-blown converter during slag discharge after dephosphorization. The amount of slag in the furnace after the dephosphorization was adjusted to such an extent that the influence of the variation in the conditions on the evaluation was almost negligible, and the amount of slag in the furnace after the dephosphorization was about 20 t.

(non-common conditions)

When slag was discharged by tilting the converter after the dephosphorization, the amount of slag discharged, the slag discharge time, and the final tilting angle of the converter were evaluated by changing the method of adding the sedative (including the addition conditions and the addition position), the retention of the sedative in the surface layer portion of the slag, the type, the addition amount, and the particle size of the sedative.

Here, the amount of slag discharged was actually weighed by a weigher provided on the base plate of the slag discharge pan. The end of slag discharge is a time point that is earlier than either a time point at which the slag discharge time reaches 3.0min (the maximum time during which slag discharge is possible) from the time limit or a time point at which the molten iron starts to flow out from the furnace opening. The final tilting angle of the converter is a tilting angle at the slag discharge completion time when the converter is set to a vertical state of 0 °. In the common conditions of the examples and the comparative examples, when the tilting angle is around 83 °, the remaining volume in the furnace and the volume of the molten iron are almost equal, and the molten iron starts to flow out from the furnace mouth, so that the final tilting angle of 83 ° is almost the upper limit. In this case, the slag discharge is terminated at the time point (tilting angle 83 °) when the molten iron starts to flow out from the furnace mouth.

(non-common conditions and results)

The conditions and results of the respective levels are shown in the table of fig. 3.

Here, as the conditions for adding the sedative, "a method of storing and feeding the sedative in a plastic bag at 10kg units from above 5m from the upper end of the residue removing pot" and "a method of adding the sedative in a granular form through a tube from above 2m from the upper end of the residue removing pot" were compared. The former sedatives are more prone to submerge into the interior of the foaming slag than the latter.

Further, as the positions of addition of the sedatives, "the vicinity of the slag falling position" and "the positions other than the vicinity of the slag falling position" were compared. Also, the former sedatives are more likely to be submerged in the foamed slag than the latter.

Further, the retention of the sedative agent in the surface layer portion of the upper surface of the slag was judged by visual observation. "none" is a case where the slag is instantaneously entrained in the slag, and "some" is a case where the slag temporarily (on the order of several seconds) stays on the upper surface of the slag. However, in the case of "adding to the vicinity of the slag falling position by the method of adding granular substances through a pipe from above 2m from the upper end of the slag extractor", the retention of the sedative on the surface layer portion of the slag surface can be visually confirmed except for the case where visual judgment is difficult.

Since it is important to rapidly calm the blisters with a small amount of a sedative and to remove a large amount of slag in a short time as an index for evaluating blister sedation, evaluation was performed with the amount of the sedative added and the average slag removal rate (slag removal amount/slag removal time).

First, levels 1 to 4 are comparative examples, and at least one of the method of adding a sedative and the type of sedative is different from the method of the present invention.

The reason why level 1 is more excellent than level 2 is considered to be that "molded products of pulp slag and slag" used as a sedative is originally intended to be a substance that is killed by rapidly generating gas by penetrating into the interior of foamed slag.

In

levels

3 and 4, although viscosity-reducing substances were used as the sedatives, it is considered that no effect was exhibited because the sedatives were trapped in the surface layer portion on the upper surface of the slag and thus the sedatives were trapped in the slag. Among these,

levels

3 and 4 provide the same or greater effect with a smaller amount of sedative than

levels

1 and 2, but are unbalanced in terms of sedative cost.

Next, levels 5 to 12 are examples, and higher foaming sedative effect was observed at all levels compared with comparative examples.

The method of the present invention was changed to level 4 and level 5, which are comparative examples, so that the equivalent average slag removal rate was obtained and the amount of added sedative agent was significantly reduced.

Level 6 changed the type of sedative (viscosity-reducing substance) from level 5, but the effect was almost the same as level 5.

Levels 7 to 9 changed the amount of the sedative (viscosity-reducing substance) added (the amount of the sedative added per unit) relative to level 5. The average slag removal rate is improved by setting the addition amount of the viscosity reducing agent to 2kg or more per 1t of the amount of slag discharged. On the other hand, from the results of level 9, it is clear that there is a region in which the effect is saturated even if the amount of added sedative agent is increased.

Levels 10 to 12 varied the particle size (ratio of particle size of 10mm or less) of the sedative (viscosity-reducing substance) relative to level 8. The average slag removal rate is improved by setting the ratio of substances having a particle size of the viscosity-reducing substance in the range of 10mm or less to 70 mass% or more. On the other hand, from the result of level 12, there is a region in which the effect of increasing the particle size by 10mm or less is saturated.

As described above, in the examples of the present invention, the amount of the sedative added and the average slag removal rate were superior to those of the comparative examples. It is clear that the examples of the present invention are superior in foaming sedation compared with the comparative examples. In addition, foaming sedation can be achieved more effectively by setting the amount of addition and particle size of the sedative to appropriate conditions.

Claims

1. A method for calming the foaming of discharged slag when slag is discharged from a refining reaction vessel to a slag receiving vessel,

wherein, the method comprises the following steps:

adding a substance having a viscosity-reducing effect as a foaming sedative, allowing the substance to stay on the upper surface layer portion of the slag discharged into the slag receiving vessel, and when adding the substance having a viscosity-reducing effect, adding the substance while avoiding the vicinity of a slag falling position in the slag receiving vessel.

2. The foaming sedation method for a discharged slag of claim 1, wherein,

3. The foaming sedation method for a discharged slag according to claim 1 or 2, wherein,

4. The foaming sedation method for tapping slag according to any one of claims 1 to 3, wherein,

5. The foaming sedation method for tapping slag according to any one of claims 1 to 4, wherein,

6. The foaming sedation method for tap slag according to any one of claims 1 to 4, wherein,

7. The foaming sedation method for tap slag according to any one of claims 1 to 4, wherein,

8. The foaming sedation method for tapping slag according to any one of claims 1 to 4, wherein,

9. The foaming sedation method for tap slag according to any one of claims 1 to 4, wherein,

10. The foaming sedation method for tapping slag according to any one of claims 1 to 4, wherein,

11. A refining facility is provided with:

a refining reaction vessel, and

wherein the refining facility further comprises a guide for adding foaming and calming agent so as to stay on the surface layer part of the slag discharged to the slag receiving vessel, and when adding the foaming and calming agent, the foaming and calming agent is added while avoiding the vicinity of the position where the slag in the slag receiving vessel falls,

the guide member has a sliding slope surface,