Petroleum-based maltha mixture and sealing material for molten metal outlet

Abstract

Provided is a petroleum-based maltha mixture which has a low polycyclic aromatic hydrocarbon concentration and is easy to adjust according to the viscosity for use, and also provided is a sealing material for a molten metal melt outlet, which releases a small amount of polycyclic aromatic hydrocarbons when used. A petroleum-based maltha mixture obtained by mixing petroleum-based maltha having a softening point of 40 DEG C or more but less than 150 DEG C and distillate having a boiling point in the range of 230-280 DEG C, the distillate content being 10-45 mass%, with the balance being petroleum-based maltha and unavoidable impurities. In addition, a sealing material for a molten metal outlet, which is obtained by mixing the petroleum-based maltha mixture as a binder with a fire-resistant raw material. The content of benzo [a] pyrene and naphthalene, which are polycyclic aromatic hydrocarbons, is controlled.

Description

Technical Field

[0001] The present invention relates to a petroleum-based soft asphalt mixture and a sealing material for a molten metal outlet using the mixture as a binder. Background Art

[0002] In the past, anhydrous tar obtained by dehydrating coal tar was used as a binder for sealing materials for molten metal outlets such as blast furnace melt outlet sealing materials and electric furnace melt outlet sealing materials (hereinafter also referred to as "mud material"), a binder for coatings, etc. Among these, regarding mud materials, Patent Document 1 discloses that anhydrous tar with a high fixed carbon content is used as a binder in refractory raw materials such as wax stone, clinker, and alumina, and refractory materials such as carbonaceous materials, silicon carbide, silicon nitride, and clay. In addition, Patent Document 2 discloses that tar-based soft pitch obtained by tar distillation is used as a binder for mud materials.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2003-286513;

[0006] Patent document 2: Japanese Patent Application Publication No. 2006-028423. Summary of the invention

[0007] Problems to be solved by the invention

[0008] The anhydrous tar described in Patent Document 1 provides an excellent slurry material, but the anhydrous tar is produced from a carboniferous coal tar raw material and therefore contains a large amount of polycyclic aromatic hydrocarbons represented by benzo[a]pyrene or naphthalene. Therefore, it volatilizes under high temperature conditions and has a problem of adversely affecting the environment. In addition, the anhydrous tar preferably has a viscosity suitable for various uses, but it is not easy to adjust the viscosity.

[0009] Furthermore, the higher the carbonization yield of the binder described in Patent Document 2, the higher the density of the molded product, and the higher the strength can be achieved. However, there is a problem that the above-mentioned polycyclic aromatic hydrocarbons may be released from the coal tar-based raw materials, which may have an adverse effect on the environment.

[0010] The object of the present invention is to provide a petroleum-based soft asphalt mixture, which has a low concentration of benzo[a]pyrene and naphthalene as representative polycyclic aromatic hydrocarbons and is easy to adjust in viscosity; and also to provide a sealing material for a molten metal melt outlet, which releases a small amount of polycyclic aromatic hydrocarbons when used.

[0011] Means for solving problems

[0012] The present inventors have conducted intensive studies to achieve the above object and have found that a mixture of a petroleum-based soft asphalt having a low softening point and a distilled oil which is a distillation fraction in a specific boiling point range has a low content of polycyclic aromatic hydrocarbons and has no adverse effect on the environment.

[0013] The present invention has been completed as a result of further studies based on the above findings, and the gist of the present invention is as follows.

[0014] [1] A petroleum-based soft asphalt mixture, characterized in that it is a petroleum-based soft asphalt mixture mixed with the following substances:

[0015] Petroleum-based soft asphalt having a softening point of 40°C or higher and less than 150°C; and

[0016] Distilled oil with a boiling point range of 230℃~280℃,

[0017] The content of the distilled oil is 10% to 45% by mass.

[0018] The balance is the above-mentioned petroleum-based soft asphalt and inevitable impurities.

[0019] [2] The petroleum-based soft asphalt mixture described in [1] above, characterized in that the benzo[a]pyrene content is less than 500 mass ppm and the naphthalene content is less than 1.00 mass %.

[0020] [3] The petroleum-based soft asphalt mixture described in [1] or [2] above, characterized in that the viscosity at 60°C is 100 mPa·s to 2400 mPa·s.

[0021] [4] A sealing material for a molten metal outlet, characterized in that it is composed of the petroleum-based soft asphalt mixture described in any one of [1] to [3] above and a refractory raw material.

[0022] [5] The sealing material for the molten metal outlet described in [4] above is characterized in that the mixing ratio of the above-mentioned petroleum-based soft asphalt mixture is 10 to 25 parts by mass relative to 100 parts by mass of the total amount of the above-mentioned refractory raw materials.

[0023] Effects of the Invention

[0024] According to the present invention, the concentration of benzo[a]pyrene and naphthalene, which are representative polycyclic aromatic hydrocarbons, can be suppressed to a low level, and a petroleum-based soft asphalt mixture whose viscosity can be easily adjusted according to the application can be obtained. In addition, a sealing material for a molten metal outlet using the petroleum-based soft asphalt mixture as a binder can reduce the amount of polycyclic aromatic hydrocarbons released. DETAILED DESCRIPTION

[0025] Hereinafter, the present invention will be described in more detail.

[0026] [Petroleum-based soft asphalt mixture]

[0027] The petroleum-based soft asphalt mixture of the present invention is a mixture of a specific petroleum-based soft asphalt obtained by distilling and heat-treating petroleum-based heavy oil and a distillation fraction in a specific boiling point range obtained by distilling petroleum itself or distilling carbonaceous or petroleum-based tar (hereinafter also referred to as "distilled oil").

[0028] [Petroleum-based soft asphalt]

[0029] The petroleum-based soft asphalt of the present invention is produced by a distillation step and a subsequent thermal reforming step using a petroleum-based heavy oil having a carbon-to-hydrogen atomic ratio (C / H) of 0.70 or more as a raw material. More specifically, it is as follows. The petroleum-based heavy oil is distilled by atmospheric distillation (as an example, the petroleum-based heavy oil is distilled in a distillation tower at about 320°C for 1.0 hour), and the fraction below 280°C is distilled off. Thereafter, the residue after distillation is heat-treated at 300°C to 380°C for about 6.0 hours to obtain a petroleum-based soft asphalt. The obtained petroleum-based soft asphalt is hot-filtered to remove solid components. Through the above operation, the softening point of the obtained petroleum-based soft asphalt is above 40°C and below 150°C. This is because when the softening point is below 40°C, the fixed carbon decreases, and when it is above 150°C, the viscosity is high and the fluidity decreases. It is preferably 40° C. to 140° C., more preferably 40° C. to 110° C., further preferably 40° C. to 70° C., and most preferably 40° C. to 57° C. The softening point can be adjusted by the heat treatment temperature and the treatment time, and can also be adjusted by remixing the light components removed by distillation or heat treatment as appropriate.

[0030] The obtained petroleum-based soft asphalt has a boiling point of about 100°C or more and is composed of a variety of complex components. Examples of such components include pentadecane (C 15 H 32 ) represented by straight-chain fatty acids and their compounds or phenanthrene (C 14 H 10 ) or its compounds, etc.

[0031] It should be noted that the petroleum-based heavy oil refers to a heavy crude oil whose specific gravity at 15 / 4° C. is classified as 0.903 or more in terms of the physical properties of petroleum crude oil.

[0032] As a property of the petroleum-based heavy oil, the fixed carbon content is preferably 1.0% by mass to 40.0% by mass, and more preferably 5% by mass to 30% by mass.

[0033] The carbon / hydrogen atomic ratio (C / H) is preferably in the range of 0.70 to 1.30, and more preferably in the range of 0.75 to 1.25.

[0034] [Distilled oil]

[0035] As described above, distilled oil is a specific distillation fraction obtained by distilling petroleum itself or distilling carbonaceous or petroleum tar, and the distilled oil of the present invention is a fraction having a boiling point range of 230° C. to 280° C. This is because when the boiling point is lower than 230° C., the fixed carbon decreases, and when it exceeds 280° C., the viscosity increases.

[0036] The object to be distilled is petroleum itself or carbonaceous or petroleum tar, but petroleum itself or petroleum tar is preferred from the viewpoint of low content of polycyclic aromatic hydrocarbons such as benzo[a]pyrene and naphthalene.

[0037] By mixing the distilled oil having a boiling point in the above range with the above petroleum-based soft asphalt, a petroleum-based soft asphalt mixture containing almost no polycyclic aromatic hydrocarbons can be obtained. That is, the benzo[a]pyrene content described below can be suppressed to less than 500 mass ppm, and the naphthalene content can be suppressed to less than 1.00 mass %.

[0038] [Polycyclic aromatic hydrocarbons]

[0039] Polycyclic aromatic hydrocarbons are hydrocarbons composed of only aromatic rings that do not contain heteroatoms or substituents such as nitrogen, oxygen, and sulfur. They are also called fused cyclic hydrocarbons. There are many types of substances. For example, there are naphthalene, which is composed of two simple six-membered rings (benzene rings), anthracene or phenanthrene, which have three benzene rings, pyrene, which have four benzene rings, or There are many substances with 6 or more benzene rings, such as benzo[a]pyrene, which has 5 benzene rings. Moreover, many substances, such as benzo[a]pyrene, are toxic and volatile, which are carcinogenic.

[0040] [Benzo[a]pyrene, naphthalene]

[0041] Among the polycyclic aromatic hydrocarbons contained in the petroleum-based soft asphalt mixture, the present inventors focused on benzo[a]pyrene and naphthalene. These hydrocarbons are representative polycyclic aromatic hydrocarbons and have adverse effects on the environment, such as carcinogenicity. Therefore, it is important to limit the content of these substances.

[0042] First of all, benzo[a]pyrene is a polycyclic aromatic hydrocarbon composed of five benzene rings. 20 H 12 Benzo[a]pyrene is a volatile substance with a boiling point of 310°C to 312°C and is considered to be carcinogenic to humans. It should be noted that there are benzo[e]pyrene isomers with different benzene ring conformations.

[0043] The content of benzo[a]pyrene in the petroleum-based soft asphalt mixture of the present invention is preferably less than 500 mass ppm. This is because when it is more than 500 mass ppm, carcinogenic substances increase. It is more preferably less than 200 mass ppm, and most preferably less than 160 mass ppm.

[0044] Secondly, naphthalene is the simplest polycyclic aromatic hydrocarbon formed by the combination of two benzene rings, and its chemical formula is C 10 H8 means that it has a boiling point of 218°C, is more volatile, flammable, allergenic, and is also a carcinogen.

[0045] The naphthalene content in the petroleum-based soft asphalt mixture of the present invention is preferably less than 1.00 mass %. This is because when it is 1.00 mass % or more, it becomes a specific chemical substance. It is more preferably less than 0.80 mass %, further preferably less than 0.70 mass %, and most preferably less than 0.55 mass %.

[0046] However, if a carboniferous asphalt is used, it contains a large amount of polycyclic aromatic hydrocarbons, and thus contains about 500 mass ppm or more of benzo[a]pyrene and 3 mass % or more of naphthalene. Therefore, it is shown that the petroleum-based soft asphalt mixture of the present invention is a material with a low content of benzo[a]pyrene or naphthalene and excellent in terms of the environment.

[0047] In addition, in order to measure the content of polycyclic aromatic hydrocarbons such as benzo[a]pyrene and naphthalene, it can be obtained by gas chromatography-mass spectrometry.

[0048] [Viscosity adjustment and mixing ratio]

[0049] In the case of mixing a petroleum-based soft asphalt mixture as a binder with a refractory raw material to produce a mud material, the viscosity of the binder plays a great role in the hardness (durability) required as a refractory (mud material). Therefore, it is necessary to make the viscosity of the binder appropriate. Here, the hardness required as a mud material can be measured using a needle penetration hardness tester, and the preferred hardness is 7000N to 4000N.

[0050] In the petroleum-based soft asphalt mixture of the present invention, a petroleum-based soft asphalt mixture with any viscosity can be obtained by changing the mixing ratio of petroleum-based soft asphalt and distilled oil. In the use of mud materials, the preferred range of the viscosity of the petroleum-based soft asphalt mixture at 60°C is 100mPa·s to 2400mPa·s. If the viscosity at 60°C is lower than 100mPa·s, the adhesion as a binder is insufficient, and the fixed carbon is reduced, so sometimes undesirable situations such as reduced durability may occur. On the other hand, if the viscosity at 60°C exceeds 2400mPa·s, the amount of the petroleum-based soft asphalt mixture used to obtain the necessary filling properties increases, so sometimes undesirable situations such as increased porosity and reduced durability may occur. More preferably, it is 400mPa·s to 1200mPa·s.

[0051] The petroleum-based soft asphalt mixture preferably has a fixed carbon content of 20.0 to 45.0% by mass and a carbon / hydrogen atomic ratio (C / H) of 0.80 to 1.30. Within these ranges, the hardness increase rate is small.

[0052] Regarding the viscosity adjustment as described above, the mass ratio (%) of petroleum-based soft asphalt (A) and distilled oil (B) can be obtained by containing them in a ratio of A:B=55-90:45-10. That is, the petroleum-based soft asphalt mixture of the present invention is a mixture obtained by mixing petroleum-based soft asphalt (A) having a softening point of 40°C or more and less than 150°C and distilled oil (B) having a boiling point range of 230°C to 280°C. Furthermore, it is a mixture in which the content of distilled oil (B) is 10% by mass to 45% by mass, and the balance is petroleum-based soft asphalt (A) and inevitable impurities. Moreover, the preferred mixing ratio is A:B=71-90:29-10, and the most preferred mixing ratio is A:B=76-86:24-14.

[0053] It should be noted that the method for mixing the petroleum-based soft asphalt (A) and the distilled oil (B) is not particularly limited, and they may be mixed using a common mixing device according to their respective mixing ratios.

[0054] [Unavoidable impurities of the mixture]

[0055] When the above-mentioned petroleum-based soft asphalt and tar or petroleum distillate are mixed, tar residue and the like may be mixed in as impurities. The content of these impurities is acceptable if it is 0.1 mass % or less.

[0056] [Sealing material for molten metal outlet (slurry material)]

[0057] In the case of a slurry material using conventional tar-based soft asphalt (anhydrous tar) as a binder, particularly when exposed to high atmospheric temperatures in an iron or steel plant, volatile components such as naphthalene volatilize, lose their softness, and are sometimes difficult to use. In contrast, the slurry material of the present invention is characterized in that it has excellent storage stability. That is, even if the slurry material is stored for a long time, the properties of the slurry material, such as the softness (hardness) of the slurry material, will not change. In addition, since there are few volatile components such as naphthalene, there will be no adverse effects on the working environment.

[0058] The petroleum-based soft asphalt mixture of the present invention can be used in various applications such as slurry materials, impregnation materials for refractory or carbon materials, binders for carbon materials, and coating binders. The following description will take the case of using it as a slurry material as an example.

[0059] The slurry material of the present invention contains a petroleum-based soft asphalt mixture and a refractory raw material. As the refractory raw material, a refractory raw material for a slurry material known in the art can be used. For example, wax stone, clinker (aggregate of refractory bricks), alumina (bauxite), carbonaceous materials (graphite, coke, etc.), silicon carbide, silicon nitride, clay (kaolin clay), etc. can be mentioned.

[0060] [Mixture ratio of mud materials]

[0061] The sealing material (slurry material) for the molten metal melt outlet of the present invention is obtained by mixing the above-mentioned petroleum-based soft asphalt mixture of the present invention at a ratio of 10 to 25 parts by mass relative to the total amount of the above-mentioned refractory raw materials of 100 parts by mass. If the mixing ratio of the petroleum-based soft asphalt mixture is less than 10 parts by mass, the lubricity is reduced, so sometimes undesirable situations such as failure to fill the necessary amount may occur. On the other hand, if it is more than 25 parts by mass, the porosity increases, the durability is reduced, and sometimes undesirable situations such as gas emission when opening the hole due to not drying may occur. Therefore, the mixing ratio of the petroleum-based soft asphalt mixture is preferably 10 to 25 parts by mass. More preferably, it is 15 to 20 parts by mass.

[0062] It should be noted that the method for producing the mud material is a method of mixing an appropriate amount of a petroleum-based soft asphalt mixture into the above-mentioned refractory raw material. The method is not particularly limited and can be mixed using a common mixing device according to various mixing ratios.

[0063] The slurry material of the present invention as described above has less change in its softness (hardness), and the hardness increase rate in the heat preservation test described later is 30% or less, which is significantly more effective than conventional slurry materials.

[0064] Example

[0065] Hereinafter, the present invention will be described in more detail according to the examples. However, the following examples are only used to illustrate the present invention in more detail and do not limit the scope of the present invention. It should be noted that, unless otherwise specified, the "parts", "%" and "ppm" recorded below are mass standards.

[0066] [Example 1]

[0067] 100 parts of petroleum-based heavy oil having a carbon concentration of 91.1%, a hydrogen concentration of 7.8%, i.e., a carbon / hydrogen atomic ratio C / H of 0.97, were distilled in a distillation tower at about 320°C for 1.0 hour, and fractions with a boiling point of less than 280°C were removed, followed by a heat treatment step at 360°C for 6.0 hours to obtain petroleum-based soft pitch A. In addition, a heat treatment step at 380°C for 6.0 hours was performed to obtain petroleum-based soft pitch B. The obtained petroleum-based soft pitches A and B were subjected to hot filtration to remove solid components. As a result, solid components such as petroleum-based soft pitch tar residue were not contained.

[0068] Here, during the distillation of the petroleum-based heavy oil, a fraction at 230° C. to 280° C. is collected as distillate oil. The distillate oil does not contain a solid component.

[0069] The properties of the above-mentioned petroleum-based heavy oil as a raw material, the obtained distilled oil, and the petroleum-based soft asphalt A and B were measured by the following measurement methods. The results are shown in Table 1.

[0070] (Viscosity measurement conditions)

[0071] The viscosity was measured using a Brookfield B-type rotational viscometer in accordance with "Viscosity of liquids - Measurement method" of JIS Z 8803 (1991).

[0072] (Softening point measurement conditions)

[0073] The softening point of tar pitch was measured in accordance with "6. Method for measuring softening point of tar pitch (ring and ball method)" of JIS K 2425 (1983).

[0074] (Measurement conditions of fixed carbon)

[0075] The measurement was conducted using an electric furnace in accordance with "9. Quantitative method for fixed carbon content" of JIS K 2425 (1983).

[0076] (Measurement conditions of water content)

[0077] The content of carbonyl alcohol was measured by volumetric titration using the Karl Fischer method in accordance with JIS K 0068 (2001).

[0078] (Conditions for determination of benzo[a]pyrene and naphthalene content)

[0079] The content was determined using gas chromatography-mass spectrometry and quantified according to the internal standard method.

[0080] [Table 1]

[0081]

[0082] The petroleum-based soft asphalt A or B obtained in Table 1 and distilled oil were mixed in the ratios shown in Table 2 below to obtain a petroleum-based soft asphalt mixture (Examples 1 to 5 of the present invention and Comparative Example 1). Their properties are shown in Table 2. In addition, 20 g of the obtained petroleum-based soft asphalt mixture was placed in a beaker and left in an atmosphere of 35°C for 1 week, and the naphthalene content was measured. The results are shown in Table 2.

[0083] In addition, as Comparative Example 2, coal tar was heated to 235° C. in a heating kettle for 24 hours to dehydrate and produce anhydrous tar. The viscosity of the anhydrous tar at 60° C. was 280 mPa·s, the fixed carbon was 32% by mass, the water content was 0.1% by mass, the benzo[a]pyrene content was 500% by mass or more, and the naphthalene content was 10.90% by mass. Furthermore, 20 g of the obtained anhydrous tar was placed in a beaker and left in an atmosphere at 35° C. for 1 week, and the naphthalene content was measured to be 8.90% by mass.

[0084] [Table 2]

[0085]

[0086]

[0087] [Example 2]

[0088] The following materials were prepared as refractory raw materials: sintered bauxite: 42%, silicon carbide: 20%, coke: 7%, ferrosilicon nitride: 17%, graphite: 4%, kaolin clay: 5%, wax stone powder: 4%, and metallic silicon: 1%, with the total amount being 100% (% is mass %).

[0089] 18 parts by mass of the petroleum-based soft asphalt mixture of Example 1 of the present invention in Table 2 of Example 1 was added to 100 parts by mass of the refractory raw material, and mixed to prepare a slurry material 1.

[0090] The samples of the mud material 1 before and after being kept at 70°C for 5 hours were measured using a needle penetration hardness tester (Crust hardness tester manufactured by Daiki Rika Kogyo Co., Ltd.), and the hardness increase rate was calculated using the formula {(hardness after keeping warm) - (hardness before keeping warm) / (hardness before keeping warm)} × 100.

[0091] Similarly, slurry materials 2 to 3 were prepared using the petroleum-based soft asphalt mixtures of Examples 2 to 3 of the present invention in Table 2 of Example 1, and the hardness increase rate was determined in the same manner as in slurry material 1.

[0092] Furthermore, 20 parts by mass of the petroleum-based soft asphalt mixture of Examples 4 to 5 of the present invention in Table 2 of Example 1 were added to 100 parts by mass of the above-mentioned refractory raw material and mixed to prepare slurry materials 4 to 5, and the hardness increase rate was determined in the same manner as in slurry material 1.

[0093] In addition, 25 parts by mass of the petroleum-based soft asphalt mixture of Example 1 of the present invention in Table 2 of Example 1 was added to 100 parts by mass of the above-mentioned refractory raw material and mixed to prepare mud material 6. The same operation as mud material 1 was performed to determine the hardness increase rate.

[0094] Furthermore, 18 parts by mass of the petroleum-based soft asphalt mixture of Comparative Example 1 in Table 2 of Example 1 was added to 100 parts by mass of the above-mentioned refractory raw material and mixed to prepare slurry material 7. The hardness increase rate was determined in the same manner as slurry material 1.

[0095] Furthermore, 18 parts by mass of the anhydrous tar of Comparative Example 2 in Table 2 of Example 1 was added to 100 parts by mass of the above refractory raw material and mixed to prepare a conventional slurry material, and the hardness increase rate was determined in the same manner as in slurry material 1. The above results are summarized in Table 3.

[0096] [Table 3]

[0097]

[0098] As shown in the results in Tables 1, 2 and 3 above, the petroleum-based soft asphalt mixtures of Examples 1 to 5 of the present invention contain less volatile components such as benzo[a]pyrene and naphthalene, and can be easily adjusted to an appropriate viscosity. In addition, the slurry materials 1 to 5 prepared by mixing the petroleum-based soft asphalt mixtures of Examples 1 to 5 of the present invention with a refractory raw material in an appropriate ratio can provide slurry materials with a small hardness increase rate.

Claims

1. A petroleum-based soft asphalt mixture, characterized in that: It is a petroleum-based soft asphalt mixture mixed with the following substances: Petroleum-based soft asphalt having a softening point of 40°C or higher and less than 150°C; and Distilled oil with a boiling point range of 230℃~280℃, The content of the distilled oil is 10% to 45% by mass. The balance is the above-mentioned petroleum-based soft asphalt and inevitable impurities.

2. The petroleum-based soft asphalt mixture according to claim 1, characterized in that: The benzo[a]pyrene content is less than 500 mass ppm, and the naphthalene content is less than 1.00 mass %.

3. The petroleum-based soft asphalt mixture according to claim 1, characterized in that: The viscosity at 60°C is 100 mPa·s to 2400 mPa·s.

4. A sealing material for a molten metal outlet, characterized in that: The invention comprises the petroleum-based soft asphalt mixture according to any one of claims 1 to 3 and a fire-resistant raw material.

5. The sealing material for a molten metal outlet according to claim 4, characterized in that: The mixing ratio of the petroleum-based soft asphalt mixture is 10 to 25 parts by mass relative to 100 parts by mass of the total amount of the refractory raw material.

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