JPS5849512B2 - Matsudo material for blast furnace taphole - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of a matwood material used for blast furnace tapholes, and in particular has sinterability that solves various drawbacks during use caused by carbonaceous organic binders such as tar and pinch. Concerning good pine wood.

The recent increase in production capacity due to dog-shaped blast furnaces and high-pressure operation has resulted in an increase in the number of taps per day due to lap tapping from two or more tapholes at the same time, and an increase in pressure inside the furnace. Workability, safety, etc. of opening and closing of the pig mouth have become particularly important from the viewpoint of improving the workability and production efficiency of the entire blast furnace operation.

As part of these measures, the diameter of the taphole is kept constant,
Although it is desired to stabilize the tapping time and the amount of tapped iron, the conventional mud material for closing the tap hole has not yet achieved a satisfactory result.

An object of the present invention is to improve the properties of the conventionally used mud material and to provide a material for plugging a tap hole that is suitable for high-pressure operation in a large blast furnace.

Recent large-scale blast furnaces have several tapholes, and since several tapholes are used alternately during the tapping operation, the time interval between closing and opening of the taphole is normal for the same taphole. It takes several hours, but depending on the condition of the tap duct, it can take several days, or it can take around an hour in cases of continuous tapping.

For this type of operation, the properties required of Matsudo material are: (1) It should have the most suitable fluidity for filling the tap hole with a Matsudo gun, (2) It should have a short firing time and be able to sinter quickly. To do, (
3) There is little variation in sintering strength depending on the length of firing time,
(4) It is resistant to corrosion by hot metal, molten slag, etc., there is little expansion of the tap hole diameter, and an appropriate tap hole depth is maintained.

If you use pine wood that satisfies these conditions, the molten metal surface in the furnace will always be buried at a low level, preventing secondary damage in the event of a sudden wind outage due to mechanical failure, and improving productivity and It will also play a major role in terms of safety.

Therefore, improving the quality of pine wood has become a matter of serious concern, and not only those involved in the ceramic industry but also those involved in blast furnace operations are currently working on improvements and research, but no satisfactory results have yet been obtained. It has not been done.

The wood that is commonly used today is made of a composition consisting of powder particles (maximum particle size of about 4 to 5 mm) of coke, loite, chamotte, high alumina, clay, and silicon carbide, combined with tar or other organic carbon compounds. A binder consisting of the following is added and thoroughly kneaded, and the mixture is pushed and filled into the tap hole using a matsudo gun.

When the wood filled in the furnace is heated, the volatile content in the binder is removed, and the residual carbon and refractory materials such as clay, low stone, and chamotte combine to form a strong structure.

However, the conventionally used matwood wood lacks strength when used in high-pressure operations in large blast furnaces, and to improve this, measures have been taken to increase the amount of sintered materials (metallic silicon, ferrosilicon, etc.) added. However, as the volatile content also increases, the structure of the mud material may be destroyed due to the increase in volatile gas pressure during heating, weakening the tissue bonds.
Furthermore, as the amount of a caking agent such as tar is increased, pores become larger and sintering is delayed.

Furthermore, when the amount of clay added increases, the sintering time becomes longer, the volume shrinks during sintering, the strength of the structure deteriorates, and furthermore, slag penetrates into the structure, increasing the tendency for erosion.

Therefore, as long as the conventionally used matwood material is used for the taphole of a large blast furnace operated under high pressure, it is not necessary to expand the taphole diameter or maintain a constant taphole depth against hot metal, molten slag, etc. It is possible.

The present invention makes it possible to automatically restrict the amount of carbonaceous binder added by blending an optimal amount of coarse refractory aggregate with an optimal particle size range that corresponds to the current state of the taphole. This material has good sintering properties, and has properties that are fully satisfactory for use in large blast furnace tapholes operated under high pressure.

Next, the present invention will be described in detail.

The particle size of conventional Matsudo raw material is less than 5 degrees at most, and it is mostly composed of powder, and by adding a binder made of tar or other organic carbon compounds to this material, it is forced into the tap hole using a Matsudo gun. However, the amount of binder added in this case is 15 to 20% by weight, and as the blast furnace becomes larger, the amount tends to be further increased.

As described above, the larger the amount of binder, the more volatile gas in the binder, which delays sintering and deteriorates the structure. High alumina, clay and silicon carbide powder (3.0mm
(below), the maximum part of the aggregate is 10-30 mm approximately spherical, ellipsoidal, almond-shaped, rod-shaped, or a mixture of these, i.e. 1 or 2 shapes.
By adding 10 to 40% by weight of refractory aggregate of a larger size, the amount of binders such as tar and pitch can be reduced by 2 to 8% by weight compared to conventional products.

The smaller the amount of binder such as tar or pitch to be added, the more the occurrence of cracking in the wood during operation is suppressed, and the wood that can be sintered quickly can be obtained.

By reducing the amount of binder, the amount of volatilization decreases, and by using such aggregate, air permeability can be increased and volatilization of the binder can be further promoted, resulting in early-strength matwood wood. .

Furthermore, in terms of quality, it has low porosity, increases density, and further increases compressive strength, and the aggregate makes the effect of connecting fine powder parts even more effective, so it is possible to increase bending strength.

The taphole of a blast furnace is opened with a drill at the beginning of tapping when the hole is opened.
It has a diameter of 0 to 50 mm, but when it expands to a diameter of 70 to 80 mm due to erosion and abrasion of hot metal and slag, tapping is completed and it is closed.

Because openings are made with a drill, the aggregate in the wood must be a material that can be opened.

If it's too hard, you won't be able to drill it with a drill.

In addition, the shape and size of the aggregate are limited to those that can be extruded with a matsudo gun at the time of closure.

Furthermore, adhesion to the wood material press-fitted into the furnace is also important, and it is particularly preferable to use aggregate made of the same material as the fine powder part or carbonaceous aggregate, but it is also effective to use aggregate that is made of the same material as the fine powder part. If so, there are no particular restrictions on the material.

As for the shape of the refractory aggregate, as a result of various studies from the above viewpoints, we selected a shape that has good mobility and is easy to operate with a muzzle gun when opening and closing.

In other words, it is approximately spherical, ellipsoidal almond-shaped, and rod-shaped, but these shapes are not meant to be expressed in a strict sense.
This is a general term for anything that roughly resembles these shapes.

One or more of these shapes may be used.

The shape of the refractory aggregate has a maximum size (length dimension) of 10-
30 friends.

Examples of each shape are shown in Figure 5, where a is spherical;
b is an oval shape, C is an almond shape, and d is a rod shape, and the size l of the maximum portion is defined as shown in the figure.

Ordinary botanicals are pressure-molded in advance to remove the volatile content of the binder by heating to make them strong, and then crushed to be used as spherical aggregates, or to be used as spherical, ellipsoidal, almond-shaped, or rod-shaped. An aggregate shaped like this is used as the refractory aggregate of the present invention.

The refractory aggregate can be made of any material such as natural refractory raw materials, synthetic refractory raw materials, carbon products, etc. to fully exhibit its effect.

The material of the refractory aggregate according to the present invention can be blended with any conventionally commonly used refractory materials (compositions), and can fully exhibit the purpose and effect of the present invention and be put to practical use.

Next, FIGS. 1 to 3 show characteristic tests regarding the results of experiments and prototypes carried out to perfect the pine wood material of the present invention.

Further, Table 1 shows the formulation of the present invention and the formulation of the conventional product A-1 for the characteristic tests shown in FIGS. 1 to 3.

Codes A1, A2, A3, &4(
1 to 3) is the maximum size l of each spherical refractory aggregate, that is, the diameter is 10
The addition ratio (weight) of particle sizes of m-sized, 20-sized, 30 mm, and 40 mm is 10%, 20%,
30% and 40% were described.

The refractory aggregate used in the present invention in the above table is made of matwood wood that has been kneaded in advance according to the conventional product composition shown in the table, that is, high alumina, chamotte, low stone, coke, silicon carbide, clay, and tar in the indicated proportions. The length of the maximum part l of the spherical shape was divided into four types: 1011Lm, 20Lm, 30Lm, and 40Lm, and was shaped at a pressure of 200kg/crrt.
Dry for 30 hours in a tunnel-type drying oven maintained at ~400°C, and then thoroughly remove volatile components until the maximum part is 400°C.
Various types of refractory aggregates were obtained.

These aggregates were kneaded based on the formulation shown in Table 1, and the wood material was further formed into a rectangular parallelepiped measuring 230 x 100 x I 00 mm using an air rammer to prepare a test piece.

The size of the maximum part l of this spherical shape, that is, the diameter, is divided into the above four types, and each is 10%, 20%, 30%, and 40%.
1, 2, and 3 are graphs showing the results of measuring the characteristic values (strength) of 16 types of specimens with 4 types of compounding codes.

In addition, in Figures 1 and 2, curves A, B, C, and D indicate the sizes of refractory aggregates of 10 mm, 20 mm, 30 mm, and 40 mm, respectively, and curves E, F, and G in Figure 3 indicate the size of the refractory aggregate, respectively. The cases where the time is 3 hours, 6 hours, and 10 hours are shown.

Among these, the size of the largest part, that is, the ball diameter 1-20mm
Test specimens from AI to A4 in Table 1 containing spherical refractory aggregates were dried at a temperature of 300° C. for 10 hours, and the quality was compared with conventional product A-1. Table 2 shows the results.

As shown in Table 2, as compared to conventional product A-1, as the amount of refractory aggregate added in the present invention increases, the apparent porosity decreases and the bulk specific gravity (indicating the degree of filling) increases.

In addition, as for strength properties, both compressive strength and bending strength increase up to 30% by weight of refractory aggregate added, but they tend to gradually decrease when the content exceeds 40% by weight.

All of the other refractory aggregate blends of the present invention were tested under the same conditions, and as shown in Figure 1: Effects of Refractory Aggregate Size and Addition Amount on Compressive Strength, regardless of the aggregate size, It can be seen that by adding aggregate, the compressive strength is significantly improved compared to the conventional matwood material.

Also, 1 = 10mm, 20mm, 301rL of fireproof aggregate
The strength gradually improves to 7IL, but when it reaches a size between 40 and 40, the strength tends to decrease compared to those mixed with other aggregates.

Moreover, the strength is the highest when the amount of aggregate added is 20% by weight when l=10 mm, and the strength decreases when the amount added is larger than that.

This tendency is also seen for the aggregate with l = 20 mm, and l
In the case of =30mm aggregate, the strength reaches its maximum value at 20% by weight and suddenly decreases.

An aggregate blended product with l=40 mm reaches its maximum strength when added at 10% by weight, and when added in an amount greater than that, the strength is extremely reduced.

In addition, since the diameter of the taphole is usually 70 to 80mmφ, the maximum dimension of the aggregate of the present invention to be mixed with the button material should be limited to no more than 30mm to ensure smooth filling into the taphole. I expected.

This was done in consideration of the possibility that if aggregate with a size close to 1/2 of the diameter of the taphole was used, problems would arise during the loading process.

These experimental results revealed that the addition of refractory aggregates having the shape and size according to the present invention to botanicals increases the strength.

Therefore, it was determined that the optimum amount to be added is 10 to 40% by weight.

Moreover, FIG. 2 shows the influence of the size of the refractory aggregate and its addition amount on the bending strength.

This also shows the same tendency as the compressive strength shown in FIG.

Next, FIG. 3 shows the relationship between drying time and compressive strength.

This is for a 1=30mm addition product of fireproof aggregate.
The drying time was changed to 3 hours (E), 6 hours (F), and 10 hours (G) at a temperature of 0°C to show how effective the product of the present invention is in terms of tar volatilization rate. .

As the amount of aggregate added increases, the difference in drying time and compressive strength (strength in two forks) decreases; this difference is not so noticeable when 20% by weight of aggregate is added, and almost no difference is seen when 30% by weight is added. It disappears.

From these results, it was confirmed that the product of the present invention has early strength.

Further, a confirmation test was conducted using a mud material extrusion tester as shown in FIG. 4 to determine whether good extrusion operation was possible with the mud gun according to the present invention.

In FIG. 4, the mat material 1 charged into the machine is pushed out by the piston 2 from the press-in direction 3 toward the discharge port 4.

In the device used, φA=100miφ, φB-5 in the figure.
It was 0 關φ.

Using this device, a conventional mud material (composition of conventional product A-1 shown in Table 1) and a product of the present invention, also shown in Table 1, were prepared. 2 combinations (refractory aggregate 1 = 20 mm, 20 wt% additive)
We conducted a comparative test with

As a result, the extrusion pressure of the conventional A-1 matwood material was 130
ky/cy4, whereas the product of the present invention weighs 135 kg.
/crrt, and it was confirmed that there was almost no difference between the two, and that sufficient extrusion was possible as before.

Next, Table 3 shows the results of a practical test using the mud material of the present invention in the taphole of a large blast furnace having a capacity of 45,000 m.

Sake 2 combination product in Table 1 (1 = 20 mm weight % of fireproof aggregate
The pine wood (added) was put to practical use for plugging tapholes for 10 days.

Amount of button material used per time: 10. 5 tons/time, i.e. 1
Used 10 times a day, 5 tons/day.

The number of times the button material was used in 10 days was set to n=100.

X: Average value σ: Standard deviation Considering this track record, the tapping time was 19 minutes longer with the product of the present invention even though the tapping speed was almost the same, which is why the tap hole was prevented from expanding. proves that it did.

This contributes to stabilizing the tapping time and the amount of tapped iron.

In addition, the fact that the tap hole depth of the product of the present invention is 320 mm larger means that hot metal (hot water) can be taken out from a deeper place, and the tap time is correspondingly longer (as mentioned above, the tap hole depth is 320 mm).
), the surface of the hot metal becomes lower, which is advantageous for management.

That is, the amount of tapped iron increased by about 10%, in other words, the number of times of tapping was reduced by 2 times/day, and the amount of wood used could be reduced by about 10%.

The properties of the pine wood binder used in the examples are as follows.

(The tar in Table 1 on page 10 is coal-based tar.) Even when coal-based and petroleum-based tars and phenol are blended as binders, the physical property values show the desired effect as shown in Table 4. Proven.

That is, conventionally used binders such as tar and organic resin can be widely used.

In addition to the aforementioned formulation A-1, formulation A-2 shown in Table 4
, A-3, For the compositions B-1, B-2, and B-3, the refractory aggregate was of the same composition and had a length of 1 = 20 mm (the same method as in A-1 above). Added 20% by weight of each &
As a result of experiments on 5, 6, 7, 8, and 9, the physical properties
A similar effect was obtained in reducing the amount of binder used.

The binder used had the properties shown in Table 5.

This invention version. 5, 6, 7, 8, and 9 were used in a 4500 m'' high-pressure blast furnace in the same way as Tsuta 2. ,B-
Compared to 3), the tap time is approximately 14% and the tap depth is approximately 10%.
%, and its effect was confirmed.

Therefore, it has been found that the refractory aggregate of the present invention can provide a significant improvement effect by adding 10 to 40% by weight of any currently commonly used wood materials.

As described above, the mud material of the present invention was able to prevent the expansion of the tap hole, as seen by the extension of the tapping time and the decrease in the tapping rate, and the tapping time and amount of tapped iron were stabilized.

In addition, the depth of the tap hole can be extended, and from this result, the product of the present invention has higher wear resistance, corrosion resistance, early strength, and quick hardening properties than conventional products, and is suitable for large blast furnace tap ports. It was confirmed that this material is the most suitable for this purpose.

[Brief explanation of drawings]

Figure 1 is a graph showing the influence of the size and amount of refractory aggregate added on compressive strength in the present invention. Figure 2 is a graph showing the influence of the size and amount of refractory aggregate added on bending strength in the present invention. Figure 3 is a graph showing the effect of the experiment, and Figure 4 is a graph showing the relationship between drying time and compressive strength of the product of the present invention.
The figure is a schematic side cross-sectional view of a mud material extrusion tester used in extrusion experiments of products of the present invention, and FIG. 5 illustrates the shape of refractory aggregate, respectively. In the figure, curves A, B, C, and D indicate the maximum size of the refractory aggregate of 10 mm, 20 mm, 30 mm, and 40 mm, respectively.
Curves E, F, and G indicate drying times of 3, 6, and 10 hours, respectively, where 1 is the wood material, 2 is the piston, 3 is the press-fitting direction,
4 indicates the discharge port, and l indicates the size of the maximum part of the refractory aggregate.

Claims (1)

[Claims] 1. A wood material for blast furnace tapholes containing 10 to 40% by weight of refractory aggregate consisting of one or more types of substantially spherical, ellipsoidal, almond-shaped, or rod-shaped aggregates with a thickest part of 10 to 30 mm.