JPH0539516A - Furnace for producting molten iron and method therefor - Google Patents

Abstract

PURPOSE:To execute operational control by directly measuring molten iron surface, temp., components, etc., during operation of a cylindrical furnace for producing pig iron using scrap and iron ore as iron source. CONSTITUTION:In the cylindrical furnace having an opening part for exhausting gas and charging raw material at upper part, a primary tuyere at lower part of furnace wall, a secondary tuyere at upper furnace wall and an iron tapping hole and a bottom blowing tuyere at furnace bottom or lower furnace wall, and a measuring hole 13 is arranged at furnace wall below the primary tuyere. Various kinds of measuring instruments are inserted from this measuring hole, and based on this measuring data, the operational control is executed. By this method, the iron tapping corresponding to the aimed production can be executed, and the temp. and components of molten iron can be precisely adjusted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a furnace for producing hot metal using iron ore and scrap as an iron source, and a method for producing hot metal using the furnace. The present invention relates to a hot metal manufacturing furnace and a hot metal manufacturing method, in which the hot metal is accurately tapped according to the components and the production amount and does not hinder the subsequent hot metal treatment process.

[0002]

2. Description of the Related Art At present, most of pig iron is manufactured by a blast furnace. The blast furnace pig iron method itself has been improved over the years and has become extremely excellent as a mass production technology for pig iron. However, the blast furnace pig iron method uses sintered ore as an iron source and high-quality coke as a fuel (reducing material), and there is a restriction on the raw fuel that can be used. Further, the blast furnace in recent years has become enormous, and since it is not possible to easily stop and restart it once it has been fired, it lacks flexibility in responding to changes in demand for steel products.

In order to solve the above-mentioned problems of the conventional blast furnace ironmaking method, the present applicant uses a cylindrical furnace similar to a converter for steelmaking and uses a new iron ore and scrap as an iron source. A pig iron manufacturing method and a manufacturing apparatus have been proposed (JP-A 1-2907).
No. 11, Japanese Patent Application No. 1-286735). In the pig iron manufacturing method, a cylindrical furnace 1 of a converter type as shown in FIG. 1 is used. As shown in the figure, the tubular furnace 1 has an opening (furnace opening) 2 for discharging the gas inside the furnace and charging the raw material in the upper part of the furnace, and a primary support for injecting a combustion-supporting gas and fuel as necessary into the lower part of the furnace wall. It has a tuyere 3, a secondary tuyere 4 for injecting combustion-supporting gas into the upper furnace wall, a taphole 5 at the furnace bottom, and a slag outlet 10 for discharging slag. As shown in FIG. 2, this furnace preferably has a structure capable of tilting and having a basin 13 for adjusting the amount of tapping.

In order to produce hot metal using the above-mentioned tubular furnace 1, first, a coke packed layer 7 is formed in the lower part of the furnace, and a scrap and iron ore packed layer 8 is formed thereon. Then, a combustion-supporting gas (oxygen-containing gas) is blown into the lower coke layer 7 from the primary tuyere 3 to cause the reaction of the following formula (1), and the reaction heat keeps the coke layer 7 at a high temperature.

C + 1 / 2O ₂ → CO + 29,400 kcal / kmol · C (1) CO generated in the above formula (1) is blown from the secondary tuyere 4 in the packed layer 8 of scrap and iron ore Gas and the following
The reaction of formula (2) (secondary combustion) occurs. The heat of reaction is used to heat and melt scrap and iron ore.

CO + 1 / 2O ₂ → CO ₂ +67,590 kcal / kmol CO (2) The iron ore (molten iron oxide) melted by this reaction is dropped into the lower coke layer 7 and the high temperature coke and the following (3 ), The reaction is performed and the product is immediately reduced.

Fe ₂ O ₃ + 3C → 2Fe + 3CO −108,090 kcal / kmol · Fe ₂ O ₃ (3) In the reaction of the above formula (3), CO ₂ does not exist in the vicinity, so CO
₂ does not hinder the reaction of formula (3). Then, the CO generated by the equations (1) and (3) is secondarily burned in the packed bed 8 of scrap and iron ore, so that it is effectively used for heating and melting the scrap and the iron ore to achieve high fuel efficiency. ..

In the above method, the ore charged from the upper opening of the furnace is Mn, Cr, M in addition to ordinary iron ore.
Ore rich in o, Ni, etc. or oxides thereof can be used. In addition to these ores and cokes, auxiliary raw materials such as silica stone, limestone, serpentine, and fluorite can be charged. As for scrap, it is possible to use high alloy scrap such as stainless steel scrap and reuse the useful elements therein. The iron ore can be blown with the powdered ore not only from the upper opening of the furnace but also from the primary and / or secondary tuyere.

The combustion-supporting gas blown from the primary tuyere and the secondary tuyere is the O ₂ -containing gas as described above, but from the primary tuyere, together with the combustion-supporting gas, pulverized coal, heavy oil, natural gas, etc. It is desirable to blow a gaseous or liquid fuel. A tuyere (not shown) with a desulfurizing agent such as CaO on the bottom of the furnace
It is also possible to produce low-sulfur pig iron by bubbling from.

For slag and tapping, when the slag naturally separated from the hot metal in the furnace is at a level above the slag outlet, and when the hot metal is at a level below the slag outlet, the furnace body is tilted and the slag is tilted. Is discharged from the slag opening, and then the hot metal is discharged from the tap opening.

As described above, according to the above-described method for producing molten pig iron proposed by the applicant of the present invention, molten pig iron can be produced from scrap and iron ore with good thermal efficiency in a tubular furnace of the converter type.

[0012]

The hot metal produced in the furnace as described above is subsequently presented to the steelmaking process by a converter or the like. However, fluctuations in the production amount (amount of tapping metal), molten metal components and Fluctuations in the hot metal temperature have a great influence on these subsequent steps.

In the cylindrical furnace previously proposed by the present inventors, as shown in FIG. 2, a part of the furnace volume is used as a buffer for tapping in a fixed amount. In that case, the same furnace is actually manufactured. There is a problem that the kneading volume becomes small and the production amount decreases. If the amount of hot metal produced in the furnace and accumulated at the bottom of the furnace can be accurately grasped, the above-mentioned buffer is unnecessary because the operation can be performed until the target amount of hot metal is reached. That is, if the hot metal level can be measured at any time during the operation of the furnace, the above obstacles will be eliminated. Further, if the temperature of the hot metal in the furnace can be measured and the hot metal can be sampled, various operation management can be performed easily and accurately, and the hot metal temperature and components can be easily adjusted to the target values.

The present invention has been made to solve the above-mentioned problems with the object of accurately controlling the operation of the cylindrical furnace.
An object of the present invention is to provide an apparatus and an operating method capable of accurately adjusting the temperature, composition, production amount and the like of hot metal while maintaining the packed bed system which is a characteristic of a cylindrical furnace.

[0015]

SUMMARY OF THE INVENTION The present invention is summarized by the following device (1) and method (2).

(1) Furnace outlet for gas discharge and raw material charging in the upper part, primary tuyere in the lower part of the furnace wall, secondary tuyere in the upper part of the furnace wall, tapping at the bottom or bottom of the furnace wall A cylindrical furnace having a mouth and a bottom tuyer, further having a measurement hole in the lower furnace wall of the primary tuyere, the measurement hole being the lower end of the opening in the furnace when the furnace is not tilted. Is at a height that is not soaked in the molten metal and penetrates the furnace wall obliquely upward toward the outside of the furnace.

(2) Using the above hot metal production furnace, a coke filling layer is formed from the bottom of the furnace to a level including the primary tuyere, and iron ore and scrap are filled up to the level including the secondary tuyere After forming the layer, a method for producing hot metal by injecting a combustion-supporting gas and fuel from the primary tuyere, a combustion-supporting gas from the secondary tuyere, a temperature measuring device from the measurement hole, a hot metal sampler, At least one of a slag sampler and a molten metal level measuring instrument is inserted, and at least one of the temperature, the components, and the production amount of the hot metal is adjusted based on the measurement data obtained thereby, and a method for producing hot metal.

Since the basic structure of the hot metal manufacturing furnace of the present invention is the same as that shown in FIGS. 1 and 2, only the measurement hole will be described in detail.

FIG. 2 is an enlarged cross-sectional view of an essential part showing a measurement hole portion of the furnace of the present invention. The measurement hole 13 is located below the primary tuyere 3,
It is provided so as to penetrate the furnace skin 14 and the refractory lining 15 and be inclined upward toward the outside of the furnace. The lower surface 13-1 of the end of the measurement hole inside the furnace is located above the level of the hot metal when the furnace is allowed to stand without being tilted (the upper surface of the hot metal that can be accumulated before tapping). If the furnace inner end 13-1 of the measurement hole is lower than the molten metal level, the molten metal cannot be measured. Further, during various measurements, it is necessary to intensify the gas purge to prevent the intrusion of hot metal into the measurement holes, and the temperature measurement accuracy deteriorates due to a decrease in the furnace temperature and the like.

Valves 18 and 18 'are attached to the outer end of the measuring hole 13 via a connecting portion 16 to prevent the gas and the like in the furnace from being ejected. Keep these valves closed when not making measurements. When making a measurement, insert the end 19 of the meter into the tube 17 and open the gland-packing type valve 18 ',
Further push the measuring instrument end portion 19 and tighten the gland packing so that gas etc. does not leak. Then the valve 18 is'opened 'and the meter end 19 is placed in the furnace.

As the above-mentioned measuring device, a device for measuring a molten metal surface
(For example, a level gauge used to measure the level of molten steel),
A temperature measuring device (for example, a thermocouple placed in a ceramic protective tube), a sampler for hot metal and slag (for example, a sampler made of paper tube for drawing molten steel, etc.) is used.

The operation of the furnace of the present invention having such measurement holes will be described below together with the method of hot metal production of the present invention in which the furnace is used.

[0023]

[Function] The furnace is of the packed bed type as described above, but since the packing material floats on the hot metal, various equipment can be inserted into the furnace to avoid temperature fluctuations, temperature measurement, metal sampling, and molten metal level measurement. Etc. can be performed, and various controls can be performed using the data as described below.

Control of Hot Metal Temperature A temperature measuring instrument is inserted through the measurement hole to measure the hot metal temperature. When the temperature is lower than the target temperature, the bottom blown oxygen amount can be increased to raise the temperature. Looking at an example of the test results of the present inventor, it is possible to raise the temperature by 10 ° C. with oxygen of 15 Nm ³ / t (hot metal). Further, the same temperature raising effect can be obtained by increasing the coke charged from the furnace port by 1.5 kg / t (hot metal).

Control of hot metal production amount A hot water level measuring device (a hot water level gauge) is inserted to operate while measuring the hot water surface, and the supply of raw materials and the feeding of acid from the tuyere are continued until the hot water surface reaches a predetermined level. By continuing, a target amount of hot metal can be obtained. If tapping is performed after confirming that a predetermined amount of hot metal has accumulated, hot metal that is just enough for the target amount is sent to the next process.

Adjustment of Hot Metal Components At any time, hot metal is sampled and analyzed, and for example, carbon [C] or sulfur [S] in the hot metal can be adjusted in comparison with the target hot metal composition. For the reduction of [S], the method for producing low-sulfur pig iron disclosed in JP-A-3-47906 proposed by the present inventors can be used.

As described above, the measurement is performed using at least one of the measuring device for the molten metal surface and the temperature, the hot metal sampler, the slag sampler, etc., and the temperature, composition and production of the hot metal are based on the measurement data obtained thereby. The amount etc. can be adjusted with high accuracy.

[0028]

EXAMPLE A cylindrical furnace having the basic shape shown in FIG. 2 and having the measurement holes shown in FIG. 3 was used. Furnace dimensions of the cylindrical furnace, diameter 1.5 m, the height from the furnace bottom to the furnace opening 3.8 m, an inner volume 6.0 m ^3. This furnace has four primary tuyeres at 90 degree intervals on the side wall 0.75 m above the bottom, four secondary tuyeres at 90 degree intervals on the furnace wall 1.2 m above the bottom and 0.69 from the bottom. There is one slag outlet on m. Insert a 100 mmφ measuring hole so that the bottom edge of the furnace inner edge is 0.6
It was installed at an angle of 30 ° diagonally upward so as to be at a position of 9 m.

The measuring instruments used for temperature measurement, molten metal level measurement, and metal sampling are cylindrical with a diameter of 80 mm. A normal paper tube type sampler was used for metal sampling. The level gauge is a commercially available liquid level gauge for molten steel,
An immersion thermocouple or a ceramic-coated continuous thermometer was used for temperature measurement. During the measurement, nitrogen gas was purged so that slag and the like did not enter the measurement hole.

The basic conditions of operation are as follows. Scrap usage: 716 (kg / t-pig iron) Ore usage: 326 (kg / t-pig iron) Ore usage ratio: 25% iron equivalent limestone usage: 73 (kg / t-pig iron) Serpentine usage: 12 (kg / t-hot metal) Silica usage: 2 (kg / t-hot metal) Coke usage: 133 (kg / t-hot metal) Pulverized coal usage: 139 (kg / t-hot metal) Total fuel usage: 272 (kg / t-hot metal) target molten iron production: 8 (t / charge) iron source, the maximum dimension 400 mm, the scrap bulk density 3.5t / m ³ (iron purity 99%), having the composition shown in Table 1 Iron ore was used. As the fuel, coke and pulverized coal shown in Table 2 were used.

Then, 1400 kg / h of oxygen and pulverized coal were blown into the coke layer from the primary tuyere and oxygen of 600 Nm from the secondary tuyere.
Blow ³ / h. The total amount of bottom-blown oxygen and primary tuyere oxygen was set to 1000 Nm ³ / h. In this embodiment, in order to prepare for a shortage of hot metal due to adhesion to the upper part of the furnace, etc.
I charged a lot.

[0032]

[Table 1]

[0033]

[Table 2]

The temperature is continuously measured and the target temperature of the hot metal is 1500
C., and the amount of bottom-blown oxygen was adjusted to reach this target temperature.

Metal sampling was performed at a scheduled time when 80% of a predetermined amount was manufactured, and a component analysis was performed. The total required time was 3 minutes. When [C] is high, the bottom blown oxygen is increased, and when it is low, the bottom blown oxygen amount is decreased to adjust the target [C] to 4.0%. Immediately after performing the metal sampling, a thermometer and a level gauge were inserted to control the temperature, and the hot metal was manufactured by feeding acid until reaching the predetermined level. The results are shown in Table 3. In addition, in Table 3, the results of operation in a furnace having no measurement holes and therefore without performing the above-described various measurements and controls are listed as reference values.

As can be seen in Table 3, the hot metal temperature is 1500 ° C.
It is only ± 5 ° C variation from the target of
Also falls within the range of 4 ± 0.2%. It is clear that the effect of the present invention is extremely large when compared with the values shown as reference values. By the method of the present invention, the control accuracy is improved, as a result, the overcharge for preparing for the fluctuation is reduced,
Fuel was reduced by 20 kg / t from the basic operating conditions. In addition, since it is no longer necessary to store hot metal in the furnace bottom for adjusting the amount of tapping, the wear of refractory materials is reduced.

[0037]

[Table 3]

[0038]

EFFECTS OF THE INVENTION According to the present invention, a highly flexible pig iron is manufactured by using a cylindrical furnace which is much smaller and simpler than a blast furnace, and by using scrap together with ore as an iron source. You can Moreover, by tapping in accordance with the target production amount, it is possible to avoid the time loss, the hot metal temperature drop loss, etc. associated with the pig iron amount adjustment. In addition, the temperature and components of the hot metal can be adjusted with high precision, without disturbing subsequent processes. Further, it is possible to obtain effects such as reduction of the fuel consumption rate and reduction of wear of refractory materials.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a tubular furnace for producing pig iron from scrap and iron ore and the state of the contents inside the furnace.

FIG. 2 is a view showing a state in which a furnace body is tilted in the furnace of FIG.

FIG. 3 is an enlarged cross-sectional view of a main part of the furnace of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuharu Hanazaki Sumitomo Metal Industries, Ltd. 4-53-3 Kitahama, Chuo-ku, Osaka-shi, Osaka

Claims (2)

[Claims] 1. A furnace opening for discharging gas and charging raw materials is provided on the upper part,
A tubular furnace having a primary tuyere on the lower part of the furnace wall, a secondary tuyere on the upper part of the furnace wall, and a taphole and a bottom blower part on the bottom or lower part of the furnace wall. There is a measurement hole in the lower furnace wall, and the measurement hole is at a height where the lower end of the opening in the furnace is not submerged in the molten metal when the furnace is not inclined, and the measurement hole is obliquely upward toward the outside of the furnace. A hot metal manufacturing furnace characterized by piercing a wall. 2. A molten coke production furnace according to claim 1 is used to form a coke packed layer from the furnace bottom to a level including a primary tuyere, and iron ore to a level including a secondary tuyere on it. After forming a packed layer of scrap, a method for producing hot metal by injecting a combustion-supporting gas and fuel from the primary tuyere, and a combustion-supporting gas from the secondary tuyere, which is a temperature measuring device from a measurement hole,
At least one of the hot metal sampler, slag sampler and molten metal level measuring instrument is inserted, and at least one of the hot metal temperature, composition and production amount is adjusted based on the measurement data obtained thereby, Production method.