JPH02285016A - Method and device for producing molten iron - Google Patents

Abstract

PURPOSE:To prevent the outflow of unmelted solid matter and to improve the unit requirement and purity of molten iron by using a cylindrical furnace provided with an inversely tapered tapping hole, bridging coke in the tapping hole and discharging molten iron from the hole. CONSTITUTION:The coke-packed bed 6 is formed in the cylindrical furnace 1 provided with the inversely tapered tapping hole 9 from the bottom to a level including a primary tuyere 3. The bed 7 packed with the iron ore and scrap is formed thereon to higher than a secondary tuyere 4 level. A combustion- improving gas and a fuel are then blown in from the primary tuyere 3 and a combustion-improving gas from the secondary tuyere 4 to operate the furnace. Coke 12 is bridged in the tapping hole 9, and the molten iron and slag 8 are discharged.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an apparatus and method for producing hot metal using scrap and iron ore as iron sources, and more particularly, an inverted taper tap hole at the bottom of a cylindrical furnace. A hot metal production equipment equipped with a hot metal production equipment, and a hot metal production equipment that prevents undissolved iron ore mixed into the hot metal and slag (hereinafter referred to as undissolved solids) from flowing out when hot metal produced by this equipment is tapped. Regarding the manufacturing method.

(Prior Art) Conventionally, scrap as an iron source has been used to a small extent as cypress wood in converter steel manufacturing, but most of it has been melted and refined in electric furnaces. However, in Japan, where electricity prices are high, as the amount of electricity used increases, power consumption increases significantly, and the advantages of using scrap are disappearing.

Therefore, the following converter scrap melting method has been proposed, in which coke or coal, which is cheaper than electricity, is used as a melting heat source and melted in a converter.

■Method for improving heat account during steel manufacturing (Japanese Patent Publication No. 56-8085), ■Reactor iron manufacturing method and apparatus (Japanese Patent Publication No. 57-8085)
198506), ■ Scrap melting and refining method (
(Japanese Unexamined Patent Publication No. 62-47417), (2) Method for producing hot metal (Japanese Patent Application No. 62-23548), and so on.

These methods include increasing the scrap content or converter steelmaking using only scrap.

However, the balance of supply and demand for scrap is extremely unstable, and as the demand increases, the price will rise, and iron and steel manufacturing methods that use scrap will be disadvantageous in terms of cost.

Therefore, the present applicant proposed a method for producing hot metal using a converter type cylindrical furnace that can use scrap and iron ore as iron sources and has high fuel utilization efficiency (Japanese Patent Application No. 122292/1982). A converter-type cylindrical furnace 1 as shown in FIG. 1 is used. As shown in the figure, this cylindrical furnace 1 has a furnace port 2 for discharging gas and charging raw materials in the upper part of the furnace, a primary tuyere 3 for blowing combustion-supporting gas and fuel into the lower part of the furnace wall, and It is equipped with a secondary tuyere 4 for blowing combustion-supporting gas into the wall, and a cylindrical taphole 5 for discharging hot metal and slag to the bottom of the furnace.

To produce hot metal using the above cylindrical furnace I, first a coke filling N6 is formed in the lower part of the furnace, and a filling layer 7 of scrap and iron ore is formed thereon. Then, combustion-supporting gas and fuel are blown into the lower coke layer 6 from the primary tuyere 3, and the following (1)
) reaction is caused, and the reaction heat causes the coke layer 6 to
keep at high temperature.

C+1/20 Wealth+CO+29,400kcal/kso
l ・C=(1) The CO generated in the above (Equation 11) reacts with the combustion-supporting gas injected from the secondary tuyere 4 in the packed bed 7 of scrap and iron ore in the upper part as shown in the following Equation (2). (Secondary combustion) occurs, and the reaction heat generated at that time is used to heat and melt the scrap and iron ore.

CO+1/20*-COx+67.590kcal/+*ol ・Co-(2) Melted iron ore (
The molten iron oxide) drips onto the lower coke layer 6, causes a reaction with the high-temperature coke according to equation (3) below, and is quickly reduced.

Feze3+ 3 C-2Fe + 3 C0-108
,090kca17kmol ・Fe,O,=・(3
) During the reaction of formula (3) above, since COl does not exist in the vicinity, the reaction of formula (3) is not inhibited by it, and in formulas (1) and (2), Since the generated CO is secondary burned in the packed bed 7 of scrap and iron ore, it is effectively used for heating and melting the scrap and iron ore, achieving high fuel efficiency.

The method for producing hot metal described above made it possible for the first time to produce hot metal from scrap and iron ore in a small furnace such as a converter.

However, this method has the following problems.

In other words, the hot metal and slag 8 stored in the furnace (see Figure 1)
is periodically discharged from the tap hole at the bottom of the furnace.

However, since this taphole is cylindrical, undissolved solids such as scrap, iron sources such as iron ore, coke, and auxiliary materials such as quicklime and silica stone flow out together with the hot metal and slag.

For this reason, there are problems in that the basic unit of the raw fuel described above deteriorates, the purity of the hot metal decreases, and the mixing ratio of raw materials in the furnace becomes unknown, making stable operation difficult.

(Problems to be Solved by the Invention) The purpose of the present invention is to prevent undissolved solids from flowing out together with hot metal and slag produced using scrap and iron ore in a converter type cylindrical furnace. An object of the present invention is to provide a hot metal manufacturing apparatus and a manufacturing method for preventing the above.

(Means for Solving the Problems) As described above, when hot metal produced in a cylindrical furnace is tapped, undissolved solids flow out. The inventors of the present invention have conducted various studies on the cause and means for preventing the undissolved solids from flowing out, and as a result, the following has become clear. That is, (1) The reason why undissolved solids flow out together with hot metal and slag is mainly due to the fact that the taphole is cylindrical.

(2) If the shape of the taphole is reversely tapered, a coke bridge will be formed there and the outflow of undissolved solids will be prevented.

(3) The outflow amount is greatly influenced by the taper angle of the taphole and the size of the coke.

This invention was made based on the above findings, and
The summary is as follows.

The first invention has a furnace port for gas discharge and raw material charging in the upper part, a primary tuyere in the lower part of the furnace wall, a secondary tuyere in the upper furnace wall, and a reverse tapered tap port in the bottom of the furnace. A second invention is a method for producing hot metal, in which coke is bridged within the inversely tapered tap hole when producing and tapping hot metal using the above-mentioned hot metal production apparatus.

(Function) Hereinafter, the molten metal production apparatus and the production method of the present invention will be explained in more detail.

FIG. 2 is a cross-sectional view of a tap hole provided in the apparatus of the present invention. This tap hole 9 has a lower diameter D, a length, and a reverse taper type with a taper angle θ. The taphole 9 is opened and closed by a taphole opening/closing device 10 as shown in FIG. and close it. When opening the tap hole 9, the opening/closing device 10 is evacuated from that position and the sand is allowed to fall, and the tap hole 9 is opened automatically. When the taphole is opened, coke is discharged together with the hot metal and the slab, and at this time, a bridge of coke 12 (diameter d) is formed in the taphole 9 as shown in FIG. This bridge prevents undissolved solids from flowing out.

The amount of undissolved solids flowing out is influenced by the diameter of the lower part of the taphole and the coke diameter d, and the taper angle θ of the taphole 9. Figure 4 shows how the amount of undissolved solids flowing out changes as D/d changes.
Line a in the figure shows the case when a taphole with a taper angle of 5 degrees (used in the present invention) is used, and line b shows the case when a taphole with no taper (conventional cylindrical taphole) is used. ing. As is clear from this figure, in both cases, as D/d increases, the amount of undissolved solids flowing out increases progressively. However, when a taper with a taper is used, the flow rate is smaller than that without a taper.
．． /, 57A, is a diagram showing the relationship between the taper angle θ of the taphole and the amount of undissolved solids flowing out. As is clear from this figure, as the taper angle θ increases, the amount of undissolved solids flowing out decreases, but when θ is 20 degrees or more, there is almost no change. It is better to set the taper angle to 20 degrees or more. However, in consideration of the difficulty in manufacturing the taphole (made of refractory material) and the reduction of wear and tear during use, it is preferable that the angle is 5 to 10 degrees.

(Example) Hereinafter, the production of hot metal and the method for producing hot metal of the present invention will be explained with reference to Examples. The bottom of the cylindrical furnace l shown in Fig. 2 has a reverse taper shape as shown in Fig. 2, and the length is 600 + I11.
, the taphole 9 with a lower diameter of 10 (lsm) and different taper angles θ (θ = 0.5, 10, 20, 30.40 degrees) was installed and operated, and undissolved solids were removed during tapping. The amount of outflow was investigated.

The specifications of the cylindrical furnace 1 are as follows: diameter 1.5m, distance from the bottom of the furnace to the furnace mouth 2 is 3.8m, internal volume is 6.0m3, and there are four holes on the side wall 0.8m above the bottom at 90 degree intervals. A primary tuyere 3 is provided, and four secondary tuyeres 4 are provided on the furnace wall 1.2 m above the hearth bottom.

The iron source has a maximum dimension of 400+mm and a bulk specific gravity of 3.5t/m'
scrap (iron purity 99%) and iron ore having the composition shown in Table 1 were used. As fuel, coke (diameter 20-50 mm) and pulverized coal having the composition shown in Table 2 were used.

In the melting operation, oxygen is supplied at 1,00Nm'/h through the primary tuyere 3 and pulverized coal is supplied at 1.
400g/h was blown into the packed bed 7 of scrap and iron ore from the secondary tuyere 4, and 60ONm''/h of oxygen was blown into the packed bed 7 of scrap and iron ore.The results are shown in Figure 7. , as the taper angle increases, the outflow variation of undissolved solids decreases significantly.

When the taper angle most suitable for the present invention is 5 to 10 degrees, the amount of variation is about half or less compared to a conventional cylindrical taphole without a taper (θ-0 degrees).

(Hereinafter, blank space) Table 1 (wt%) Table 2 (wt%) (Effects of the invention) As explained above, the hot metal production apparatus of the present invention equipped with a reverse taper type taphole is used to By carrying out the hot metal production method of the present invention in which coke is bridged in the taphole during pig ironing, it is possible to reduce the outflow of undissolved solids mixed with the hot metal and slag.

As a result, it is possible to prevent a decrease in the basic unit of the contents of the furnace, and since their contamination is reduced, there is an effect that the purity of the hot metal is improved.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional hot metal production apparatus equipped with a cylindrical taphole; FIG. 2 is a schematic sectional view of a reverse taper type taphole installed in the hot metal production apparatus of the present invention; The figure is a schematic cross-sectional view of the taphole portion of the hot metal production equipment of the present invention, and Figure 4 shows the D/d and undissolved solids outflow amount of the reverse taper type taphole used in the hot metal production equipment of the present invention. FIG. 5 is a diagram showing the relationship between the taper angle θ of the reverse taper taphole used in the apparatus of the present invention and the amount of undissolved solids flowing out. FIG. FIG. 7 is a schematic cross-sectional view of the hot metal production apparatus equipped with the inverted taper type taphole used in the example, and shows the taphole when the hot metal production method of the present invention is implemented using the hot metal production apparatus of the present invention. FIG. 3 is a diagram showing the relationship between the taper angle and the amount of fluctuation in the outflow of undissolved solids. 1 is a cylindrical furnace, 2 is a furnace mouth, 3 is a primary tuyere, 4 is a secondary tuyere,
5 is a cylindrical taphole, 6 is a coke packed bed, 7 is a scrap and iron ore packed bed, 8 is hot metal and slag, 9 is a reverse tapered taphole, 10 is a taphole opening/closing device, 11 is sand supply pipe,
12 is coke. $/mouth

Claims (2)

[Claims] (1) Hot metal production equipment equipped with a furnace port for gas discharge and raw material charging in the upper part, a primary tuyere in the lower part of the furnace wall, a secondary tuyere in the upper furnace wall, and a taphole in the bottom of the furnace. A hot metal production apparatus characterized in that the taphole is of a reverse tapered type. (2) A method for producing hot metal using the hot metal production apparatus set forth in claim 1, in which a packed bed of coke is formed from the bottom of the furnace to a level including the primary tuyeres, and a layer of coke is formed on top of the packed bed of coke. A packed bed of iron ore and scrap that reaches above the tuyere level is formed, and combustion-supporting gas and fuel are injected through the primary tuyere and combustion-supporting gas is injected through the secondary tuyere. A method for producing hot metal, which comprises bridging coke into the taphole when discharging it through the taphole.