JPS5950616B2 - Matsudo for blast furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a blast furnace tap hole produced by adding a novolak type phenol resin, a solvent for this resin, and a curing agent for the resin as a binder to the aggregate of blast furnace mud, and kneading the mixture. When the tap hole is blocked, it has excellent filling performance and strength development in the tap hole, and when the blast furnace tap hole is exclusively opened, it has excellent hole opening performance.
This article relates to blast furnace mud that has excellent corrosion resistance after opening.

During blast furnace operation, iron ore, fuel, solvent, etc. are charged from the top of the furnace.
Hot air is blown from the bottom to extract molten pig iron and slag from the furnace, and this process is performed continuously to produce pig iron.

BACKGROUND OF THE INVENTION In recent years, blast furnace operation has seen remarkable progress as blast furnaces have become more pressurized and larger.

Blast furnace mud is a material that closes the extraction port, that is, the tap hole, for extracting molten pig iron and slag from the furnace in these blast furnaces.

Conventionally, blast furnace mud has been used by kneading aggregates such as clay, chamotte, silicon carbide, and carbonaceous materials (coke) with the addition of tar-based binders such as tar and pitch, and other organic binders. Ta.

Various conditions can be considered for mud to be required as a tap hole plugging material, but generally they are as follows.

a) It must have the appropriate plasticity necessary for filling with a mud gun.

b. After filling the tap hole, the steel should quickly develop strength and have early strength properties.

C: Strong strength at high temperatures and good corrosion resistance of hot metal slag.

d. The tap hole has good openness.

e There should be no black smoke or abnormal dust generation.

etc.

Conventionally used muds in which a tar-based binder or other organic binder is added to the aggregate have various problems as no mud satisfies all of the above-mentioned conditions.

Blast furnace mud is made by inserting the mud into a mud gun, and pressing the mud into the tap hole when tapping is completed.The press-fitted mud develops strength in the tap hole, and the mud is pushed back by the furnace pressure. When the melted material in the furnace is strong enough to prevent it from flowing out of the furnace, the crimp holding of the mud gun is finished, the mud gun is turned to the original position, and the plugging of the tap hole is finished.

After a certain period of time has passed after the blockage, and the molten pig iron and slag in the furnace reach a certain level, the tap hole is opened with a drilling machine, and the molten pig iron and slag in the furnace are tapped out of the furnace. Ru.

The tapping time is usually about 60 to 180 minutes, and it is done 10 to 15 times a day.

The amount of iron tapped per operation is 200t to 600t.

The mud that has been used in the past is mainly tar mud using a tar-based binder, but in this case there is no particular problem with the plasticity when filling the tap hole with the mud, but there are other requirements. However, various problems remained.

Since the tar-based binder is thermoplastic, it does not harden due to the furnace heat after filling the tap hole hemado, and the sintering of the mud is not completed until the tar, pitch, etc. carbonize and form carbon bonds, and the mud does not melt into the furnace. Since strength is not developed even after the internal pressure has been overcome, the crimp retention of the mud gun is not completed until the binder in the mud forms carbon bonds.

For this reason, while the mud gun is held crimped, tapping from the tap hole is impossible, and in a blast furnace having only one tap hole, working efficiency and productivity are reduced.

In addition, even in the case of a blast furnace with multiple tap holes,
When a mud gun or hole-drilling machine breaks down, or when a tap runner is being repaired or replaced, it often happens that the same tap hole is used continuously for tapping. Even in this situation, since the mud gun holds the crimping for a long time, the work efficiency decreases and the productivity decreases significantly.

In addition, tar mud has a low carbonization yield of the binder tar and pitch at high temperatures, so the strength of the carbon bonds formed is low, which reduces the adhesion strength of the aggregate and has low wear resistance from hot metal and slag. It also has poor corrosion resistance.

For this reason, tap holes using tar mud suffer from severe corrosion damage, and the tapping time per tap is short.In order to secure the target amount of tap per day, it is natural that the number of taps per day must be 1.
In some cases, the number of blasts may reach around 6 times, which increases the workload of workers at the front of the furnace, and if the molten material inside the furnace cannot completely flow out of the furnace, it causes fluctuations in the furnace condition, which is unfavorable for blast furnace operation.

Furthermore, tar mud generates black smoke from the mud filled in the furnace or from inside the mud gun during or after filling with the mud.

Furthermore, as mentioned above, there is no early strength, so if holes are made with a hole punching machine before the binder of the mud has completely formed carbon bonds, the unsintered part of the mud will not have any strength. In addition, as raw tar is exposed to rapidly high temperatures due to hot metal, black smoke or abnormal dust is generated, deteriorating the working environment and causing pollution. Dust generation causes rapid expansion of the diameter of the tap hole and deteriorates corrosion resistance, and blast furnace operations have to be performed with reduced pressure and reduced airflow, often resulting in fluctuating furnace conditions and reduced productivity.

On the other hand, recently, various organic binders have been studied to replace these tar-based binders.

Conventionally, phenolic resins have generally been used as industrial materials such as electrical parts and mechanical parts.

Generally, there are two types of phenolic resins: novolac type phenolic resins and resol type phenolic resins, the former being thermoplastic and the latter being thermosetting.

When a novolac type phenolic resin is used, about 1 liter of hexamethyltetramine is added as a curing agent to it.
It is used by adding 5%, and the resol type is used by dissolving it in water or other solvent.

The present inventors believe that these phenolic resins can be applied to mud because they show a high carbonization yield at high temperatures and have early strength, and have conducted various experiments using phenolic resins as a mud compounding agent for blast furnaces. Ta.

As a result of experiments, the resins commonly used for electrical and mechanical parts were used as they were, added to mud aggregate, and kneaded. However, various problems occur such as hardening due to the radiant heat of the tap duct, or the mud and the tap hole are burned in the tap hole when filling the tap hole, and the mud gun becomes overloaded. could not.

In addition, it is particularly difficult to store resol-type phenolic resins for long periods of time.During storage, the resol undergoes a polymerization reaction and its viscosity increases, so when the resin is added to mud aggregate and kneaded, crosstalk occurs. The wetting effect was poor, and large amounts of resin were required to maintain proper plasticity.

The reason for these problems is that the phenolic resin used as the binder lacks thermal stability at low temperatures (30 to 150°C).

In this way, applying resol-type phenolic resin alone to the head is disadvantageous in terms of storage, etc., and novolak-type phenolic resin also uses about 15% hexamethylenetetramine based on the resin. ,
Its thermal stability is poor, and its decomposition temperature decreases when it absorbs moisture, which further worsens its stability and makes it difficult for resins commonly used in electrical and mechanical parts to be used. Application as such proved to be quite difficult.

The present inventors took advantage of the characteristics of these phenolic resins,
In addition, as a result of various studies in order to obtain a product that is stable even at low temperatures and meets the requirements for mud, we added ethylene glycol and acetal resin to a novolac type phenol resin that has good shelf life at room temperature, and achieved various excellent properties. This is what we succeeded in developing with the mud.

The details of the present invention will be described below.

The blast furnace mud of the present invention is made by blending blast furnace mud raw materials such as clay, chamotte, silicon carbide, and carbonaceous raw materials with a novolac type phenol resin, ethylene glycol as a solvent for this resin, and acetal resin as a hardening agent. This is an early-strengthening blast furnace mud that is obtained by kneading and kneading and has excellent low-temperature stability, early strength, corrosion resistance, etc.

The novolac type phenolic resin in this mud is in liquid or powder form, and the amount of this resin contained in the mud is 3 to 30%.

If the resin content is 3% or less, the mud is filled into the tap hole and then
The early strength is not developed and the mud gun crimping is held for a long time, resulting in lower work efficiency and lower productivity.

In addition, if the hole is opened and tapped in a short period of time after filling with mud, the strength of the mud has not been fully developed, so the diameter of the tap hole expands significantly due to erosion of the hot metal, and hot metal overflows from the tap culvert. Alternatively, the number of times of tapping must be increased to ensure the target amount of tapped iron per day, and furthermore, it becomes difficult to completely discharge the molten material from the furnace to the outside of the furnace, which worsens the condition of the furnace. This causes trouble and is not desirable.

When the content of the resin in the mud is 30% or more, the mud has too much resin content after filling into the tap hole, so it takes a long time for the resin to harden, and the development of early strength is slow. This reduces work efficiency and productivity, and when holes are opened during short firing, the raw resin is suddenly exposed to high temperatures by hot metal, causing abnormal dust generation and causing pollution problems. sell.

In addition, regarding corrosion resistance, since the resin content is high, a large amount of decomposition gas is generated due to the decomposed fat, and if the holes are opened before the gas has completely escaped to the outside, the aggregate will be completely destroyed by the carbon bonds of the resin. Corrosion resistance is poor because it is not fixed.

In addition, because the resin content is too large, the carbon-bonded film formed around the aggregate, which is formed by carbonization of the resin, becomes thick, and the bond strength decreases, resulting in poor corrosion resistance and high price, which is not economical.

When the content of the resin in the mud is 3 to 30%, the properties of the mud after filling are smooth in the curing reaction and good in early strength.

Regarding corrosion resistance after filling, it has a large amount of residual carbon and exhibits strong carbon bond strength, so it shows good corrosion resistance.

Furthermore, there is no generation of black smoke or abnormal dust that occurs with tar mud when the holes are blocked or opened, so it is advantageous in terms of environmental hygiene and pollution prevention.

The mud according to the invention has a boiling point of 5-10% of
℃ ethylene glycol is added.

If the amount of ethylene glycol added is less than 5%, the mud cannot be given the plasticity necessary for filling with a mud gun, and the mud cannot be extruded using a mud gun.

If the amount of ethylene glycol added is 10% or more, the mud will become too soft in the mixer, and not only will it stick to the mixer wall and reduce the yield, but it will also cause damage to the mud gun plunger, etc. when used in a mud gun. It adheres to the walls, requiring cleaning inside the gun, and after filling the tap hole, hardening is delayed due to excessive ethylene glycol, and early strength is not developed. The entire pighole filling mud becomes porous and corrosion resistance decreases.

When the amount of solvent added is 5 to 10%, the cross-contamination of the mud is good, and the filling plasticity with a mud gun is also good, so that smooth filling of the mud into the tap hole is possible.

Furthermore, the pore opening properties after filling are also good because appropriate pores are formed in the center of the mud.

The mud according to the present invention is a formaldehyp-generating substance, in particular thermoplastic at 160°C, in order to further improve the early strength and corrosion resistance of the novolac type phenolic resin and to maintain and improve the stability of the mud at low temperatures. Thus, a predetermined amount of acetal resin that thermally decomposes at 196 to 232°C to generate formaldehyde is added.

The acetal resin decomposes at the above-mentioned temperature of 196 to 232°C to generate formaldehyde, and acts as a crosslinking agent for the novolac type phenol resin.

In this way, the acetal resin is thermally decomposed at a high temperature of 196 to 232°C to generate formaldehyde, the acetal resin is added in a predetermined amount as described below, and as mentioned above, ethylene glycol with a boiling point of 190°C is added. Therefore, even when heating cross-wires are carried out or when exposed to high temperatures in a mud gun, the mud is hardly affected by the heat and remains stable and satisfactorily achieves its initial purpose.

In other words, after the mud is inserted into the mud gun, it hardens due to the radiant heat of the tap hole, or when filling the tap hole, the tap hole and the mud burn in the tap hole, causing the mud gun to become overloaded. This eliminates the occurrence of various troubles such as

On the other hand, after the mud is filled into the tap hole, the ethylene glycol in the mud evaporates due to the furnace heat, and the acetal resin becomes 160%.
It softens and melts at 160°C and is compatible with the novolac type phenol resin, which is already liquid at 160°C or lower, melting and integrating, and the homogeneous compatible material wets the refractory particles.

During this time, ethylene glycol continues to evaporate and is completely evaporated at 190°C, but the compatible solution penetrates into the pores formed by the evaporation and forms a continuous compatible film on the particle surface and within the pores. do.

After that, the acetal resin in the above compatible solution is 193-23
Formaldehyde is generated at 2°C.

This formaldehyde cross-links to the novolac-type phenolic resin, forming continuous three-dimensional bonds on the surface of the refractory particles in the mud and within the pores, reducing the average pore diameter, promoting early strength, and reducing carbonization. It improves the carbon bonding rate and forms strong carbon bonds to develop strong bonding strength.

Furthermore, since the crosslinking reaction is carried out in the absence of ethylene glycol, the cured mud product is fired without incorporating ethylene glycol into it, thereby making it possible to prevent the occurrence of cracks.

As a result, infiltration of slag into the mud during hole opening and tapping is effectively prevented, slag resistance is improved, and high corrosion resistance is exhibited.

In addition, the acetal resin is mixed in advance with the novolak type phenolic resin, mixed with a resin solution that is a mixture of the above phenol resin and the above solvent, or mixed with the aggregate for mud at the time of crosstalk and the above phenol resin and the solvent. It is mixed together with the above aggregate and phenol resin solution.

The amount of the acetal resin added to the novolac type phenol resin is 0.5 to 10%.

If the amount of acetal resin added to the novolac type phenolic resin is 0.5% or less, the amount of these curing agents added to the resin is too small, and the amount of formaldehyde generated by its decomposition is too small. , the crosslinking effect is small and the amount of three-dimensional hardening formed is small, so there is no early strength, and the carbonization yield is low, so the bond strength is low and the corrosion resistance is also poor.

As a result, work efficiency is reduced, productivity is poor, and corrosion resistance is poor, requiring many taps to obtain the target daily tap amount, increasing the workload at the front of the furnace, and If the molten material in the furnace is not completely discharged, it is undesirable because it causes fluctuations in the furnace condition and worsens the furnace condition.

Acetal resin 1 for novolac type phenolic resin
Mud containing 0% or more generates too much formaldehyde due to decomposition, so the mud burns and hardens in the high temperature part of the taphole while filling the taphole, so the mud gun does not overheat during filling. This becomes a load and makes filling difficult, causing trouble.

- Also, unreacted formaldehyde that does not participate in the crosslinking agent is generated, which inhibits the densification of the mud and reduces corrosion resistance.

Novolac type phenolic resins with 0.5 to 10% acetal resin have good early strength development and high carbonization yield at high temperatures, forming strong carbon bonds and good corrosion resistance. is obtained.

As a result of practical use of the mud to which acetal resin was added in the predetermined amount, it hardly decomposed even when heated and mixed, there was no problem of hardening even in a mud gun, and the tap hole could be filled smoothly.

In addition, the crimping holding time is 10 to 20 minutes, which is approximately 1/4 to 1/2 that of conventional tar mud, allowing for a 20% increase in iron production, and improved corrosion resistance by 1.5% due to improved slag resistance. ~
This has been improved by a factor of 2, which reduces the number of taps per day, reduces the work load at the front of the furnace, and also allows for stable blast furnace operation as it follows changes in furnace conditions well.

Next, examples of the present invention will be described.

As shown in Tables 1 and 2, clay, chamotte, silicon carbide, and coke were used as the mud aggregates used in the Examples and Comparative Examples, and ethylene glycol was used as the solvent.

First, Example 1 shown in Table 1. 2. Let's talk about 3.

Example 1. 2. Regarding No. 3, 15% of novolak type phenolic resin was added, and acetal resin was added as a formaldehyde generating substance to the resin at a concentration of 0.5 to 10%.
% was added in the test.

Because acetal resin has a higher decomposition temperature than other formaldehyde-generating substances, the mud gun retention time is 10~
Although it was a little long at 20 minutes, it did not affect work efficiency, and a stable tap flow with good corrosion resistance was obtained.

Next, Comparative Examples 1 and 2 shown in Table 2 will be described.

Comparative Example 1 Since the amount of Acecool resin added was too small, the holding time of the mud gun was prolonged and black smoke was also generated.

Comparative Example 2 Because the amount of acetal resin added was too large, the mud and tap hole were burned during filling, making filling impossible and unusable.

Next, Comparative Examples 3 and 4 shown in Table 3 will be described.

Comparative Example 3 uses hexamethylenetetramine, which generates formaldehyde without melting at 60° C., as a curing agent for novolac type phenolic resin, and Comparative Example 4 uses tar mud.

In addition, Table 1. 2. 3 (Tapping time/Tapping time) is an index of the slag resistance of the mud, and the larger this ratio is, the better the slag resistance of the mud is.

From the Examples in Table 1 and the Comparative Examples in Tables 2 and 3 above, it is clear that the mud of the present invention has a small average pore diameter of 20 to 30 μm, and also has no cracks, so it has improved slag resistance. be.

Claims (1)

[Claims] 1 Novolak type phenolic resin is added to blast furnace mud materials such as clay, chamotte, silicon carbide, and carbonaceous materials.
~30%, 5 to 10% of ethylene glycol, and 0.5 to 10% of acetal resin to the above novolac type phenol resin are blended and kneaded to produce ethylene glycol 5.
A mud for blast furnaces that has a residual content of ~10% and is plastic, and has excellent filling properties in blast furnace tap holes, strength development, pore opening properties, and corrosion resistance.