JP2006028423A - Synthetic tar and blockage material for tap hole of molten metal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a synthetic tar containing reduced amounts of volatile ingredients, having excellent storage stability without changes of the viscosity, etc., during long storage and allowing easy viscosity adjustment according to applications. <P>SOLUTION: The tar is a mixture comprising soft pitch obtained by distillation of tar and distillate oil obtained by distillation of tar and contains 1.5 mass% or less of naphthalene. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a synthetic tar and a plugging material for a molten metal outlet (hereinafter referred to as “mud material”), and more specifically, to provide a synthetic tar and a mud material which are excellent in storage stability and whose viscosity can be freely adjusted. To do.

Conventionally, anhydrous tar obtained by dehydrating tar has been used as a binder for mud materials such as a blast furnace outlet closing material and an electric furnace outlet closing material, a binder for paint, and the like. Among such applications, mud materials have been manufactured using refractory materials such as rholite, chamotte, and alumina and refractory materials composed of carbonaceous materials, silicon carbide, silicon nitride, clay and the like, and tar as a binder. . As these tar binders, it has been proposed to use anhydrous tar having a high fixed carbon content (Patent Document 1).
JP-A-10-324576

  The anhydrous tar described in Patent Document 1 provides an excellent mud material. However, the anhydrous tar contains a volatile component (mainly naphthalene and the like), and an anhydrous tar containing such a volatile component. When tar is used as a binder for the mud material, there is a problem that the structure of the mud material becomes rough due to volatilization (sublimation) of naphthalene and the like, which causes cracks. In addition, if the anhydrous tar is stored, naphthalene and the like will volatilize during storage, adversely affecting the environment, increasing the viscosity of the anhydrous tar, and causing problems during actual use. ing. The anhydrous tar preferably has a viscosity suitable for the application depending on the application, but it cannot be said that the adjustment of the viscosity is easy. Furthermore, conventional anhydrous tar contains phenol, and these phenols are also problematic as environmental pollutants.

  Accordingly, an object of the present invention is to provide a synthetic tar that has few volatile components, has excellent storage stability that does not change its viscosity even when stored for a long period of time, and can be easily adjusted in viscosity according to the application. Another object of the present invention is to provide a mud material in which the structure is not altered or cracks are not generated.

  The above object is achieved by the present invention described below. That is, the present invention is a synthetic tar characterized in that it is a mixture of soft pitch obtained by tar distillation and distilled oil obtained by tar distillation, and the naphthalene content is 1.5% by mass or less. I will provide a. The synthetic tar preferably has a viscosity at 60 ° C. of 100 to 2,400 mPa · s and / or a phenol content of 0.1% by mass or less.

  The present invention also provides a mud material comprising a refractory material and a binder, wherein the binder is the synthetic tar of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the anhydrous tar which has few volatile components, is excellent in the storage stability which does not change the viscosity etc. even if it stores for a long period of time, and can adjust viscosity easily according to a use can be provided. Furthermore, according to the present invention, it is possible to provide a mud material that is excellent in storage stability and hardly changes in structure or cracks.

  Next, the present invention will be described in more detail with reference to the best mode for carrying out the invention. The “synthetic tar” in the present invention is a mixture of soft pitch obtained by tar distillation and distilled oil obtained by tar distillation. Here, the soft pitch is obtained by dehydrating tar to form dehydrated tar (anhydrous tar), and further distilling by atmospheric distillation to obtain a 200-250 ° C fraction (naphthalene oil) and a 230-280 ° C fraction. Remaining kettle residue after distilling off the water (called distilled oil, washing oil, absorption oil, etc.) with a softening point of less than 70 ° C and a boiling point of 350 ° C or more Meaning a mixture of high-boiling components and free carbon. These soft pitches preferably have a softening point in the range of about 35-45 ° C.

  Distilled oil means the above-mentioned fraction of 230 to 280 ° C. The synthetic tar of the present invention is obtained by mixing the above soft pitch and the above distilled oil, and this mixture is referred to as “synthetic tar”, and the naphthalene content is 1.5 mass as described later. % Or less. The conventional anhydrous tar relative to the synthetic tar means dehydrated tar before atmospheric distillation in the above, and light components such as naphthalene oil are not removed, and mainly naphthalene is usually 8 to 15 mass. In addition, phenol is contained in an amount of about 0.5 to 1.5% by mass.

  The synthetic tar of the present invention is obtained by mixing the soft pitch and the distilled oil, and an advantage that a mixture (synthetic tar) having an arbitrary viscosity can be obtained by changing the mixing ratio of the soft pitch and the distilled oil. Have The preferred viscosity of the synthetic tar is in the range of 100 to 2,400 mPa · s at 60 ° C. Such a viscosity adjustment is obtained by mixing the soft pitch (A) and the distilled oil (B) in a mass ratio of A: B = 74 to 90: 26-10. When the viscosity at 60 ° C. is less than 100 mPa · s, the adhesiveness as a binder is insufficient, and fixed carbon is reduced, which may cause inconveniences such as reduced durability. On the other hand, when the viscosity at 60 ° C. exceeds 2,400 mPa · s, the amount of tar for obtaining the required filling property increases, which may cause inconveniences such as increased porosity and reduced durability. is there. For reference, the relationship between the content of distilled oil in synthetic tar and the viscosity of synthetic tar is shown in FIG. As shown in the figure, the viscosity of the synthetic tar of the present invention can be arbitrarily and easily changed according to the purpose by changing the content of the distilled oil.

  The synthetic tar of the present invention is characterized in that the naphthalene content is 1.5% by mass or less. When the naphthalene content in the synthetic tar exceeds 1.5% by mass, it becomes difficult to solve the problem of the present invention. As a method for reducing the naphthalene content in the synthetic tar to 1.5% by mass or less, a special method is unnecessary, and as described above, an anhydrous tar containing light components such as naphthalene is distilled to obtain naphthalene or the like. A method of distilling off the light components and further distilling to separate anhydrous tar into distilled oil and soft pitch, and then mixing (synthesizing) the distilled oil and soft pitch in the above-mentioned mixing ratio is preferable. Since both the distilled oil and soft pitch used in this case have a low naphthalene content, the naphthalene content of the resulting synthetic tar is 1.5% by mass or less.

Moreover, it is preferable that the phenol content of the synthetic tar of this invention is 0.1 mass% or less. The method for adjusting the phenol content in the synthetic tar of the present invention to 0.1% by mass or less is the same as the adjustment of the naphthalene content.
The synthetic tar of the present invention is useful for many applications such as mud materials, refractories, carbon material impregnation materials, special carbon binders, paint binders and the like. Hereinafter, the use as a mud material will be described as a representative example.

  The mud material of the present invention comprises a refractory material and a binder, and the binder is the synthetic tar of the present invention. As the refractory material, any conventionally known refractory material for mud materials can be used, for example, a refractory material such as rholite, chamotte, alumina and the like, and a refractory material made of carbonaceous material, silicon carbide, silicon nitride and clay. Is mentioned. The mud material of the present invention is obtained by mixing the synthetic tar (B) of the present invention at a ratio of 10 to 25 parts by mass with respect to 100 parts by mass of the refractory material (A). If the amount of the synthetic tar used is less than the above range, the lubricity is lowered, and there may be a disadvantage that the necessary amount cannot be filled. On the other hand, when the amount of the synthetic tar used is larger than the above range, the porosity may increase, the durability may be lowered, and there may be inconveniences such as the occurrence of gas blowing during the opening due to undried.

  The characteristic of said mud material is that it is excellent in storage stability of the obtained mud material, like the synthetic tar of the present invention. That is, even if the mud material of the present invention is stored for a long period of time, the property of the mud material, for example, the softness (hardness) of the mud material does not change, and the volatile content is low. Does not adversely affect the environment. In contrast, conventional mud materials using anhydrous tar as a binder lose their softness due to volatilization of volatile components such as naphthalene, especially when exposed to high atmospheric temperatures in steelworks and steelworks. In some cases, it may become difficult and the working environment may be deteriorated. Although it has been difficult to manufacture a large amount of mud material at a time due to such curling, the mud material of the present invention does not have such curling and therefore has an advantage of improving workability.

Next, the present invention will be described more specifically with reference to examples, comparative examples and evaluation examples. In the text, “part” and “%” are based on mass unless otherwise specified.
Example 1
100 parts of raw material tar was heat-treated at about 150 ° C. for 0.5 hours in a dehydration tower to obtain 97 parts of dehydrated tar (anhydrous tar). 97 parts of the dehydrated tar was distilled by atmospheric distillation to obtain 19 parts of naphthalene oil having a fraction of 200 to 250 ° C., 4 parts of distilled oil having a fraction of 230 to 280 ° C., and 74 parts of a residue remaining as a soft pitch. The properties of the raw material tar, dehydrated tar, distilled oil and soft pitch are shown in Table 1 below.

［粘度の測定条件］
ＪＩＳ Ｚ ８８０３（１９９１）液体の粘度−測定方法に準拠してブルックフィールドＢ型回転粘度計を使用して測定した。
［軟化点の測定条件］
ＪＩＳ Ｋ ２４２５（１９８３）６．タールピッチの軟化点測定方法（環球法）に準拠して測定した。
［固定炭素の測定条件］
ＪＩＳ Ｋ ２４２５（１９８３）９．固定炭素分定量方法に準拠して電気炉を使用して測定した。
［水分の測定条件］
ＪＩＳ Ｋ ００６８（２００１）に準拠して容量滴定によりカールフィッシャー法により測定した。
［ナフタリン含有量の測定条件］
ガスクロマトグラフィーにより測定し、内部標準法にて定量を行なった。

[Measurement conditions for viscosity]
According to JIS Z 8803 (1991) liquid viscosity-measurement method, it was measured using a Brookfield B-type rotational viscometer.
[Measurement conditions for softening point]
JIS K 2425 (1983) 6. The tar pitch was measured according to the softening point measurement method (ring ball method).
[Measurement conditions for fixed carbon]
JIS K 2425 (1983) 9. It measured using the electric furnace based on the fixed carbon content determination method.
[Moisture measurement conditions]
It was measured by Karl Fischer method by volumetric titration in accordance with JIS K 0068 (2001).
[Measurement conditions for naphthalene content]
Measured by gas chromatography and quantified by an internal standard method.

実施例２
アルミナ、シリカ、炭化珪素、窒化珪素および炭素などからなる粉末耐火材料１００部に対し、実施例１の合成タール１の１８部を添加して良く混合し本発明のマッド材１を調製した。同様に合成タール５、および合成タール１０を用いて本発明のマッド材２およびマッド材３を調製した。 The above-obtained distilled oil and soft pitch were mixed at the ratio shown in Table 2 below to obtain the synthetic tar of the present invention. Their properties are also shown in Table 2.

Example 2
The mud material 1 of the present invention was prepared by adding 18 parts of the synthetic tar 1 of Example 1 to 100 parts of a powder refractory material made of alumina, silica, silicon carbide, silicon nitride, carbon, and the like and mixing them well. Similarly, the mud material 2 and the mud material 3 of the present invention were prepared using the synthetic tar 5 and the synthetic tar 10.

Comparative Example 1
The raw material tar was heated to 235 ° C. in a heating kettle over 24 hours and dehydrated to produce a comparative anhydrous tar. The anhydrous tar had a viscosity at 60 ° C. of 280 mPa · s, fixed carbon of 32%, moisture of 0.1%, and naphthalene content of 10.9%. Using this anhydrous tar, a comparative mud material was obtained in the same manner as in Example 2.

Evaluation Example 1
20 g of each of synthetic tar 1, synthetic tar 7, synthetic tar 10, synthetic tar 10 immediately after production in Example 1 and anhydrous tar immediately after cooling to 25 ° C. after dehydration in Comparative Example 1 was placed in a beaker at 1 ° C. in an atmosphere of 35 ° C. The naphthalene content and viscosity after standing for a week were measured and the results shown in Table 3 below were obtained.

Evaluation example 2
Table 4 shows the raw material compositions of the mud materials 1 to 3 prepared in Example 2 and the mud material of the comparative example. Further, the hardness (softness) of each mud material after 1 kg of each was left at 35 ° C. for 1 week was measured, and the results shown in Table 4 below were obtained. In addition, the hardness immediately after manufacture of each mud material was also measured and listed in Table 4.

The method for measuring hardness in the above table is as follows.
[Measurement method of hardness]
After the mud material was kept at 70 ° C. for 5 hours, the mud material was measured using a needle penetration type hardness meter (Crust hardness meter manufactured by Dairika Kogyo Co., Ltd.).

  As is clear from the results shown in Tables 1 to 4 above, according to the present invention, there are few volatile components, the storage stability does not change even when stored for a long time, and the viscosity can be adjusted according to the application. Synthetic tars that are easy can be provided. Furthermore, according to the present invention, it is possible to provide a mud material that is excellent in storage stability and hardly changes in structure or cracks.

The figure explaining the relationship between the ratio of the distilled oil in the synthetic tar of this invention, and a viscosity.

Claims (4)

  A synthetic tar, which is a mixture of soft pitch obtained by tar distillation and distilled oil obtained by tar distillation, wherein the naphthalene content is 1.5% by mass or less.   The synthetic tar according to claim 1 whose viscosity in 60 ° C is 100-2,400 mPa * s.   The synthetic tar according to claim 1 or 2, wherein the phenol content is 0.1 mass% or less. A plug for a molten metal tap, comprising a refractory material and a binder, wherein the binder is the synthetic tar according to any one of claims 1 to 3.

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