JP7180045B2 - Method for using raw material containing metallic iron containing Zn - Google Patents

Description

TECHNICAL FIELD The present invention relates to a technique of using raw materials containing Zn-containing metallic iron in the operation of a blast furnace.

Conventionally, in a blast furnace, iron ore and coke are alternately charged in layers from the top of the furnace, and hot air (high temperature air + oxygen) is blown from the tuyeres provided at the bottom of the furnace to remove iron ore. Hot metal is produced by temperature-programmed reduction. Iron ore and coke are charged into the furnace using, for example, a bell-less type raw material charging device provided at the top of the furnace.
This bell-less type raw material charging device rotates and tilts a raw material charging chute, called a bell-less, to alternately layer iron ore and coke sent from the top hopper into the blast furnace. is loading.

As raw materials for blast furnaces, raw materials containing metallic iron (for example, ingots, etc.) are used. In that case, Zn contained in the raw material agglomerates and forms deposits on the furnace wall. Techniques for stably operating a blast furnace by avoiding such a situation are disclosed in Patent Documents 1 and 2, for example.
Patent document 1 discloses that, when scrap car scrap containing organic and inorganic components in addition to metallic iron is used as a raw material for a blast furnace, the effect on the gas treatment system caused by the generation of tar and the adhesion of zinc to the furnace wall are avoided. It is an object of the present invention to provide a method for processing end-of-life vehicle scrap that enables stable continuous operation.

Specifically, a method of charging end-of-life vehicle scrap into a blast furnace for melting treatment, wherein the end-of-life vehicle scrap is charged from the top of the blast furnace to the vicinity of the center of the furnace. I'm doing it. In addition, scrap car scrap is charged into a furnace center region having a radius of 30% or less of the radius of the furnace, and the scrap car scrap is press-processed so that the maximum length is 1.5 m or less. , that it is preferable that scrap cars be press-processed so that the filling rate of metallic iron is 0.4 or less.

In Patent Document 2, in a situation where volatile elements such as Zn adhere to the furnace wall and adversely affect the unloading of the charge, high-concentration The purpose is to volatilize dust containing volatile elements.
Specifically, it is a method of operating a blast furnace in which iron ore 2 and coke 3 are charged from the top of the furnace and hot air or the like is blown in from tuyeres 5 to make iron. Dusts containing high concentrations of volatile elements are to be charged in a limited manner.

Japanese Patent Application Laid-Open No. 2004-250722 JP-A-11-217606

However, in Patent Literature 1, it is necessary to charge large waste car scrap having a length of 1.5 m after pressing from the top of the blast furnace to the vicinity of the center of the furnace. As a result, the gas temperature in the center of the furnace is lowered, the gas flow rate is lowered, and the dust ratio is lowered, which may deteriorate the gas permeability in the furnace. In addition, there is a risk that the center charged coke will deteriorate due to carburization, resulting in deterioration of air permeability. Therefore, there is a possibility that the coke ratio will increase.

In Patent Document 2, it is necessary to charge iron ore and dust containing a high concentration of volatile elements from the top of the blast furnace to the vicinity of the center of the furnace. As a result, the gas temperature in the center of the furnace is lowered, the gas flow rate is lowered, and the dust ratio is lowered, which may deteriorate the gas permeability in the furnace. In addition, there is a risk that the center charged coke will deteriorate due to carburization, resulting in deterioration of air permeability. Therefore, there is a possibility that the coke ratio will increase.

Therefore, in view of the above problems, the present invention enables stable operation without forming deposits derived from Zn in the furnace when using a raw material containing metallic iron containing Zn. It is an object of the present invention to provide a method of using a raw material containing Zn-containing metallic iron.

In order to achieve the above object, the present invention has taken the following technical measures.
The method of using the raw material containing Zn-containing metallic iron according to the present invention is such that when the raw material containing Zn-containing metallic iron is charged during operation of the blast furnace, Zn from the raw material containing metallic iron is The charging unit [kg/t] is 0.019 kg/t or more, and the average value for a predetermined period satisfies the formula (1).

y≤0.0014x+0.5177 (1)
However, y = heat flow ratio (temperature distribution in the height direction inside the blast furnace)
x = Wind speed in front of tuyere (speed of air blown into the furnace from the tuyere)
Preferably, the predetermined period is one week or more and four weeks or less.
Preferably, when charging into the blast furnace, the raw material containing metallic iron is mixed with iron ore.

ADVANTAGE OF THE INVENTION According to this invention, when using the raw material containing metallic iron containing Zn, stable operation can be performed without forming deposits derived from Zn in the furnace.

BRIEF DESCRIPTION OF THE DRAWINGS It is the figure which showed typically the outline of a bell-less type blast furnace. It is a figure which showed typically the condition in a blast furnace by the height difference of the wind speed in front of a tuyere. 4 is a graph showing the relationship between the tuyere front wind speed x and the heat flow ratio y. 4 is a graph showing the relationship between charging Zn from a raw material containing metallic iron and the presence or absence of shelf suspension.

Hereinafter, an embodiment of a method for using a raw material containing metallic iron containing Zn according to the present invention will be described with reference to the drawings.
The embodiment described below is an example of the present invention, and the specific example does not limit the configuration of the present invention.
First, the operation of the blast furnace 1 will be explained.

As shown in FIG. 1, in a blast furnace 1, iron ore 6 and coke 7, which are raw materials, are alternately charged in layers from a furnace top hopper 2 installed at the furnace top, and are provided in the lower part of the furnace. By blowing hot air (high-temperature air + oxygen) from the tuyere 4, the iron ore 6 is heated and reduced to produce hot metal.
In this embodiment, a bell-less type raw material charging device that charges iron ore 6 and coke 7 as raw materials into the furnace while rotating and tilting a raw material charging chute called bellless 3 provided at the top of the furnace. used.

That is, the bell-less type raw material charging device is installed at the top of the furnace, and is equipped with a top hopper 2 that stores iron ore 6 and coke 7 as raw materials, and below the top hopper 2. 3, and while turning and tilting the raw material charging chute, iron ore 6 and coke 7 sent from the furnace top hopper 2 are alternately layered. It is loaded like this.

In this embodiment, iron ore 6 and part of coke 7, and auxiliary raw materials are used as ores. The iron ore 6 includes sintered ore, pellets, and lump ore. Further, the ratio in the iron ore 6 in this embodiment is 62 to 80% by weight of pellets and 20 to 38% by weight of lump ore. Moreover, in this embodiment, limestone, silica stone, and converter slag were used as auxiliary raw materials.
In this embodiment, "charging of center charging coke 8" is carried out to charge coke 7 into the central portion of the ore layer.

A method of using the raw material containing metallic iron containing Zn according to the present invention will be described below.
Hereinafter, in the description of the present embodiment, the name of the present invention may also be referred to as "method for using Zn-containing metal".
In this embodiment, raw metals generated by blast furnace manufacturers and electric furnace manufacturers are used as raw materials containing metallic iron.

By the way, in the operation of the blast furnace 1, the hot air blowing into the blast furnace 1 is periodically stopped, and the blast furnace equipment is maintained, such as repairing the furnace body and incidental equipment, etc. there is
However, if the Zn charging unit from raw materials containing metallic iron is 0.019 kg/t or more, it is possible that blast furnace 1 will hang on the shelf in rare cases when restarting blast furnace 1 to normal operating conditions after a wind break. have a nature. If the shelf suspension occurs, the blast furnace 1 will be closed again.

It should be noted that shelf suspension means that the iron ore 6 and the coke 7 that are alternately charged in layers stop descending. Specifically, when deposits 9 are formed in the blast furnace 1, the inner diameter of the furnace becomes smaller (constricted state). In such a situation, the materials 6 and 7 are densely packed together, making it difficult for them to descend, resulting in a clogged state, resulting in "failure to unload". As a result, hollowing occurs in the blast furnace 1 .

Furthermore, in the case of the start-up of the blast furnace 1, the wind speed of the hot air blown into the blast furnace 1 from the tuyere 4 is low in the early stage of start-up, and the gas tends to flow to the peripheral part in the radial direction. The rising force of the hot air that flows and the force of the surrounding raw materials (raw materials containing metallic iron, iron ore 6, coke 7) are balanced, and the raw materials 6 and 7 do not descend, causing hanging on the shelf. It is thought that it becomes easier. In this case, the blowing of air from the tuyere 4 into the blast furnace 1 is stopped, and the rest of the air is resumed.

In order to prevent the occurrence of such hanging on the shelf, the operation of the blast furnace 1 is monitored by measuring the state of descent of the charging surface (upper surface) of the charged raw materials 6 and 7 . In other words, if the change in position in the height direction of the charging surface of the raw materials 6 and 7 is measured from the upper part of the furnace, and the measurement results show that there is no change in the charging surface, or if the change in the charging surface is less than a predetermined value , it is determined that shelf hanging has occurred.
Therefore, the operation of the blast furnace 1 is carried out so that deposits 9 are not formed in the blast furnace 1 . That is, the hot air blown into the blast furnace 1 from the tuyeres 4 forms a central gas flow that flows upward through the center of the blast furnace 1 . When the central gas flow is strong, Zn is discharged out of the furnace, making it difficult for deposits 9 to form inside the blast furnace 1 .

It is well known among those skilled in the art that Zn contained in the raw material 6 charged into the blast furnace is involved in the deposit 9 formed in the blast furnace 1 .
In this embodiment, the Zn charging unit from raw materials containing metallic iron is obtained by the following formula.
Basic unit of Zn charging from raw material containing metallic iron [kg/t] = Basic unit of raw material containing metallic iron [kg/t] × Zn concentration of raw material containing metallic iron [%]
The basic unit [kg/t] is the amount [kg] of raw materials used per 1 ton of hot metal.

Specifically, the basic unit [kg/t] can be obtained by the following formula (A).
Basic unit = Weight of raw materials used per channel [kg] ÷ Charged iron content per channel [t] ・・・(A)
Regarding the method of determining the charged iron content per channel, the iron content of the raw material used is determined in advance by analysis, and the charged amount of used raw material [t] × analyzed iron content [wt%].
However, in the present invention, the charged iron content per channel was determined by obtaining the iron content in advance for each raw material used, such as pellets and lump ores, and integrating the charged iron content.

Further, the basic unit [kg/t] can also be obtained by the following formula (B).
Basic unit = Weight of raw material [kg] used in one day or one month ÷ Weight of hot metal taken out from the tap hole in one day or one month [t] (B)
The weight [kg] of raw materials used in one day or one month and the weight [t] of hot metal taken out from the tap hole in one day or one month are obtained by load cells. be.

Although there is no problem in using either the formula (A) or the formula (B) for calculating the basic unit, the formula (A) is used in the present invention.
Now, in the present invention, even if the Zn charging unit [kg/t] from the raw material containing metallic iron is 0.019 kg/t or more, if the formula (1) is satisfied, the blast furnace 1 can be suspended from the shelf suspension. It has been found that blast furnace operation can be carried out without generating wind.

y≤0.0014x+0.5177 (1)
However, y = heat flow ratio (temperature distribution in the height direction inside the blast furnace)
x = Wind speed in front of tuyere (speed of air blown into the furnace from the tuyere)
The heat flow ratio y can be obtained by the following formula.
Heat flow ratio y=heat capacity of charge/heat capacity of blast furnace top gas Table 1 may be referred to for a specific method of obtaining the heat flow ratio y.

Table 1 shows the definition of the heat flow ratio y used in this embodiment.

The heat flow ratio y is an index of the temperature distribution in the height direction inside the blast furnace 1 . A lower heat flow ratio y indicates a wider high-temperature region.
Also, the wind speed x before the tuyere is the wind speed calculated from the flow rate of the hot air (high temperature air + oxygen) blown into the furnace from the tuyere 4 .
Table 2 should be referred to for a specific method of obtaining the wind speed x before the tuyere.

Table 2 shows the definition of the tuyere front wind speed x used in this embodiment.

The tuyere front wind speed x is one of the factors that control the gas distribution ratio of the radial distribution of the blast furnace 1 . This indicates that the higher the wind speed x in front of the tuyere, the easier the central flow. That is, when the tuyere front wind speed x is high, the blown hot air flows through the center of the blast furnace 1 .
The period analyzed in this embodiment was the average value of two weeks.
The analysis period is preferably 1 week or more and 4 weeks or less. The reason is that it takes a predetermined period of time for the adhering matter 9 to grow to a certain size, that is, to grow to a size that can be discerned. It takes at least a week or more. On the other hand, if the adhering matter 9 becomes too large, hanging on a shelf or the like will occur. After 4 weeks, the deposit 9 becomes too large, and the operation of the blast furnace 1 is affected.

In addition, the reason why the average value of the analysis period is one week or more and four weeks or less is that in the operation of the blast furnace 1, the range of operating conditions has a certain width, so there are some fluctuations. In order to cover the range of analytical values due to this fluctuation, the average value for a certain period of time was used.
Furthermore, it is preferable to use a raw material containing metallic iron mixed with the iron ore 6 when charging into the blast furnace 1 .

In this embodiment, the raw material containing metallic iron and the iron ore 6 are mixed in the skip car 5 and used (see FIG. 1).
In addition, the raw material containing metallic iron and the iron ore 6 are simultaneously charged into a belt conveyor or a furnace top hopper 2 installed at the top of the furnace, so that the raw material containing metallic iron is mixed with the iron ore 6. can be

Here, in the present invention, the fact that the Zn charging unit [kg/t] from the raw material containing metallic iron is set to 0.019 kg/t or more will be described in detail.
Zn in the iron ore 6 is in the _form of (Zn,Fe ₎ S or ZnS sulfide, (Zn,Fe) _O.Fe2O3 or _ZnO.Fe2O3 ferrite, and 2ZnO.SiO silicate. is charged into the blast furnace 1. These zinc compounds are believed to be reduced to Zn by carbon at temperatures above 900°C.

Then, Zn volatilizes (boiling point: about 900° C.), is blown upward by the blast furnace gas, and is discharged out of the blast furnace 1 .
However, part of the Zn in the blast furnace gas is cooled near the upper furnace wall and oxidized in a liquid or solid state (melting point: about 400°C) to form zincite (ZnO) with a high melting point. It is considered that deposits 9 are formed on the upper side of the furnace wall.

On the other hand, Zn in metallic iron is considered to contain elemental Zn, and forms zincite (ZnO) with a high melting point even if the temperature does not exceed 900°C, so deposits 9 are likely to form. it is conceivable that.
In the blast furnace 1, in order to stabilize the operation, the gas flow is promoted at the radial center of the furnace, and the temperature is high and the flow velocity is high at the radial center of the furnace.

Therefore, in the prior art, raw materials containing metallic iron are charged near the center of the furnace.
However, in the method of using the Zn-containing metal of the present invention, with respect to the heat flow ratio y and the wind speed x before the tuyere, when the Zn charging unit from the raw material containing metallic iron is 0.019 kg/t or more, a predetermined period ( 1 week or more and 4 weeks or less) satisfies the formula (1), so that the deposit 9 is formed on the side wall in the furnace without charging the raw material containing metallic iron near the center of the furnace. The operation of the blast furnace 1 can be carried out without forming.

In the present invention, when the Zn charging unit from raw materials containing metallic iron is 0.019 kg/t or more, the average value for a predetermined period (1 week or more and 4 weeks or less) is such that the formula (1) is satisfied. I will explain in detail what I did.
The raw material containing metallic iron used in the present embodiment is bare metal generated by a blast furnace manufacturer or an electric furnace manufacturer. The base metal consists of metallic iron, iron oxide, and impurities, and when used in the blast furnace 1, the heat required for reduction can be reduced compared to the iron ore 6.

Therefore, if raw materials containing metallic iron are used in the blast furnace 1, the reducing agent ratio and the coke ratio can be reduced.
However, raw materials containing metallic iron contain impurities such as Zn.
Zn has a melting point of about 400°C and a boiling point of about 900°C. Zn charged into the blast furnace 1 melts and evaporates in the blast furnace 1, and most of it rises with the gas flow in the furnace and is discharged outside the furnace. However, part of the Zn circulates in the furnace and agglomerates on the furnace wall to form deposits 9 .

When deposits 9 are formed in the blast furnace 1, unloading is deteriorated and fluctuations in gas flow are increased, which may lead to hanging on the shelf. Therefore, there is a possibility that the productivity in the blast furnace operation will be deteriorated or the cost will be increased due to the increase in the coke ratio.
By the way, as shown in FIG. 2, if the tuyere front wind speed x is high, the central gas flow in the furnace is promoted, so Zn does not adhere to the furnace wall and is easily discharged out of the furnace. On the other hand, when the wind speed x before the tuyere is low, the gas flows to the furnace wall side, the temperature in the furnace becomes low, and Zn may adhere to the upper side of the furnace wall to form deposits.

In addition, if the heat flow ratio y is low, the high-temperature region in the furnace expands, so the region where Zn is gas-liquid expands (that is, the region where Zn is solid decreases), and Zn is discharged outside the furnace. easier to be
Raw materials containing metallic iron are considered to generate gas-liquid Zn at a lower temperature than the iron ore 6, and are considered to form deposits 9 easily.

Thus, in the present invention, when 0.019 kg/t or more of charged Zn from a raw material containing metallic iron is used, the average value for a predetermined period (1 week or more and 4 weeks or less) satisfies the formula (1). By doing so, it is characterized in that it is possible to perform stable operation without forming deposits 9 on the furnace wall to the extent that the blast furnace 1 is suspended again due to shelf suspension generated at the start of the cold wind.
That is, in the present invention, when a raw material containing metallic iron containing Zn is charged during operation of the blast furnace, the Zn charging unit [kg/t] from the raw material containing metallic iron is 0.019 kg. /t or more, the average value for the predetermined period satisfies the formula (1).

y≤0.0014x+0.5177 (1)
However, y = heat flow ratio (temperature distribution in the height direction inside the blast furnace)
x = Wind speed in front of tuyere (speed of air blown into the furnace from the tuyere)
The predetermined period is preferably one week or more and four weeks or less.
Also, when charging into the blast furnace, it is preferable to use a raw material containing metallic iron mixed with iron ore.

According to the method of using the Zn-containing metal of the present invention, by controlling the heat flow ratio y and the wind speed x in front of the tuyere in blast furnace operation, it is possible to stably use raw materials containing metallic iron containing Zn. .
[Example]
Examples carried out according to the method of using the Zn-containing metal of the present invention are described below.

Implementation conditions in this example are as follows.
Blast furnace 1 has an internal volume of 2112 m ³ , 25 tuyeres, 2 tapholes, a raw material charging device of a bell-less type, and a furnace body cooling device of (cooling plate + sprinkled water).
The main raw materials are coke = 286-373 kg/t, lump ore = 0-549 kg/t, pellet ore = 874-1334 kg/t, and raw materials containing metallic iron = 0-130 kg/t.

Tables 3 and 4 show examples carried out according to the method of using the Zn-containing metal of the present invention.
However, period: July 2011 to September 2017, data: daily data average values from 2 weeks before scheduled wind breaks to wind breaks, wind breaks and reduced wind days excluded, metal charging Zn≧0.019kg/ is t.

FIG. 3 shows the relationship between the wind speed x in front of the tuyere and the heat flow ratio y.
In addition, the ▪ mark in FIG. 3 indicates that hanging on the shelf occurred from December 2013 to February 2014.
FIG. 4 shows the relationship between the charging Zn from the raw material containing metallic iron and the presence or absence of shelf suspension.
As shown in Figures 3 and 4, when 0.019 kg/t or more of charged Zn from raw materials containing metallic iron is used during blast furnace operation, the heat flow ratio y and If the wind speed x in front of the tuyere is controlled, sill-hanging will not occur due to the rise of the quiescent wind.

That is, when the present invention is carried out, deposits 9 are less likely to be formed on the furnace wall, and the blast furnace 1 is prevented from being subjected to re-break wind due to hanging on the shelf at the start-up of break wind.
The effect of suppressing shelf hanging can be summarized as follows.
If the tuyere front wind speed x is high, the central gas flow in the furnace is promoted, so Zn is easily discharged out of the furnace without adhering to the furnace wall.

If the heat flow ratio y is low, the high-temperature region in the furnace becomes wider, so the region where Zn is gas-liquid expands (that is, the region where Zn is solid decreases), and Zn is easily discharged out of the furnace. Become.
By satisfying the conditions of the present invention (conditions related to formula (1)), stable operation can be performed without forming deposits 9 to the extent that the blast furnace 1 is suspended again due to the suspension of the blast furnace 1 when the wind is stopped. It can be carried out.

It should be noted that the embodiments disclosed this time should be considered as examples and not restrictive in all respects.
In particular, matters not specified in the embodiments disclosed this time, such as operating conditions, operating conditions, various parameters, dimensions, weights, volumes, etc. of components, do not deviate from the range normally performed by those skilled in the art. Instead, values that can be easily assumed by those of ordinary skill in the art are adopted.

In the present invention, the bell-less type blast furnace has been described as an example, but the present invention can also be applied to a bell-armor type blast furnace.

1 blast furnace 2 top hopper 3 bellless (chute for charging raw materials)
4 tuyere 5 skip car 6 iron ore 7 coke 8 center charged coke 9 deposit

Claims (3)

During blast furnace operation, when charging raw materials containing metallic iron containing Zn,
The Zn charging unit [kg/t] from the raw material containing metallic iron is 0.019 kg/t or more,
A method of using a raw material containing Zn-containing metallic iron, wherein the average value for a predetermined period satisfies formula (1).
y≤0.0014x+0.5177 (1)
However, y = heat flow ratio (temperature distribution in the height direction inside the blast furnace)
x = Wind speed in front of tuyere (speed of air blown into the furnace from the tuyere) 2. The method of using a raw material containing Zn-containing metallic iron according to claim 1, wherein said predetermined period is one week or more and four weeks or less. Use of the raw material containing Zn-containing metallic iron according to claim 1 or 2, wherein the raw material containing metallic iron is mixed with iron ore when charged into the blast furnace. Method.

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