JP2007137934A - Method for producing coke for iron-manufacturing and raw material of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing coke for iron-manufacturing, easy for handling or operating without decreasing the strength of the product coke (for iron-manufacturing), and the raw materials of the coke for iron-manufacturing used in the method. <P>SOLUTION: This method for producing the coke for iron-manufacturing by dry-distilling blended coal in an coke oven is provided by using fluid coke and asphalt as a part of blended raw material. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing iron-making coke and a raw material for iron-making coke used in this method.

  Coke for iron making used in blast furnaces, etc. is a mixture of several types of coal, such as strong caking coal, and other raw material coals. It is manufactured by heating and dry distillation at a temperature of The strength and composition necessary for this iron-making coke can be realized by optimizing the blending of the blended raw materials in addition to the operating conditions of the coke oven.

  Conventionally, in the production of such steelmaking coke, it is conceivable to use petroleum coke for the purpose of adjusting various properties such as ash and volatile content of the ironmaking coke. For example, in the cited document 1, it is described that an inert material is used as one of raw materials for the purpose of expanding the particle size of iron-making coke, and examples of the inert material include petroleum coke and petroleum pitch. ing.

  Petroleum coke, as described in the coke note 2004 edition (edited by the Japan Institute of Energy), in addition to the effects described in the cited document 1, has conventionally been a component of a blended raw material for coke ovens. It was limited to the role as a regulator. Therefore, the main action of this petroleum coke is to adjust the ash content, volatile content, etc. of the iron making coke produced in the coke oven, and to increase the particle size of the iron making coke. That is, when petroleum coke as a pore-forming agent and coal-based pitch or petroleum-based pitch as a caking additive are added to the blended raw material, the porosity is increased, and coke having a certain level of strength can be produced. There is an explanation that it will be possible.

  However, the petroleum coke exemplified in this document refers to delayed coke produced by the delayed coking process. That is, even if petroleum coke is conventionally used, it is a method of obtaining massive and needle-like coke for iron making having excellent graphitization and low thermal expansion coefficient by adding the delayed coke.

However, petroleum coke includes what is called fluid coke, which is used for special purposes, in addition to the delayed coke. The fluid coke is manufactured by a fluid stirring technique, and is therefore manufactured as a fine powder of about 5 mm or less. However, the inventors' research has found that when producing coke for iron making, if the fluid coke is used instead of the delayed coke, the strength of the iron making coke decreases. For this reason, conventionally, fluid coke has not been used for the production of iron-making coke. In addition, since this fluid coke is produced in the form of fine powder, it is accompanied by generation of dust in the process of transportation and storage during raw material adjustment. It was difficult to uniformly mix with the raw material.
Japanese Patent Laid-Open No. 11-181439 Coke Note 2004 (Japan Institute of Energy)

  As described above, delayed coke produced by the delayed coking method is excellent in graphitization and has a low coefficient of thermal expansion, so that it is relatively easy to produce massive iron-making coke. However, when this delayed coke is added to the blended raw material, as described above, the strength of the product (for iron making) coke is reduced. The combined use of was indispensable. Generally, the decrease in coke strength is considered to be mainly caused by the decrease in the average maximum reflectance (Ro) and fluidity (MF) of the blended raw materials. That is, when using delayed coke, it is essential to recover these indices (Ro, MF) by using strong caking coal together. However, strong caking coal is expensive, and adding it causes an increase in the cost of the blended raw material.

  Further, as another method for increasing the coke strength, petroleum pitch as described in Patent Document 1 may be added in addition to the addition of strong caking coal as described above. However, this oil pitch requires special equipment called the Yurika process, and it is produced only in one place in Japan and one place overseas, and it is the same as strong caking coal in that it is very expensive. In addition, the petroleum pitch obtained by the Yurika process is unsuitable as a material for compensating the coke strength because the supply amount is limited.

On the other hand, compared to delayed coke, the fluid coke has a smaller unit structure of graphite produced in a fluidized state, and it is difficult to obtain massive coke. In fact, it is not used as a high-grade carbon material, but only as a fuel.
This time, the inventors paid attention to the fluid coke, and examined the use of the fluid coke as one of the compounding raw materials for producing iron coke. However, it has also been found that when this fluid coke is added to the raw materials for coke for iron making, it cannot be used to improve coke strength because it is difficult for the fluid coke alone to form a massive coke. Therefore, in order to use this fluid coke, it is necessary to use a larger amount of strong caking coal and petroleum pitch produced by the Yurika process than when using delayed coke. Will be invited. Furthermore, since the fluid coke has a very small particle size of 5 mm or less, it is difficult to store it in an outdoor raw material yard (because it is easily blown off by wind).

  Therefore, the present invention can solve the above-mentioned problems when producing coke for iron making using fluid coke, and in particular, handling and operation without reducing the strength of the product (for iron making) coke. It is an object of the present invention to provide an easy-to-use method for producing iron coke and a raw material for iron coke used in carrying out this method.

  As a result of intensive studies to solve the above-mentioned problems, the inventors have reached the conclusion that the adoption of the production method according to the gist configuration described below and the use of the raw materials can be effective means, and the following The method and the raw material which concern on the summary structure described in the above were developed.

  That is, the present invention is a method for producing coke for iron making, characterized in that fluid coke and asphalt are used as a part of the blended raw material when producing coal coke by dry distillation of the coal blend in a coke oven. is there.

  In the present invention, 50 to 150 parts by mass of asphalt is used with respect to 100 parts by mass of fluid coke. First, 50 to 150 parts by mass of asphalt is mixed with 100 parts by mass of fluid coke, Next, the mixture is mixed with other compounding raw materials and then pulverized, and as the asphalt, modified asphalt made of an oxidation treatment and / or an additive added to adjust the softening point is used. Is considered to be a more effective solution.

Further, the present invention is a mixture having 100 parts by mass of fluid coke and 50 to 150 parts by mass of modified asphalt modified by adding an oxidation treatment and / or an additive, and having an average particle size of 20 to 40 mm. We propose a raw material for coke for iron making.

  That is, the present invention is also used in combination with modified asphalt exhibiting predetermined characteristics when using fluid coke produced by the fluid coking method as a raw material for the production of iron coke. By doing this, it is a technique to solve the shortage of using the fluid coke as a blending raw material and to improve the strength of the coke for iron making.

  According to the present invention, even if the fluid coke, which has been used exclusively as a fuel in the past, is added to the blended raw material used for the production of iron-making coke, the strength of the product coke is not reduced and high strength is not caused. Production of coke for iron making becomes possible. Therefore, there is an effect that the range of selection of the raw material for producing coke for iron making can be expanded, and the production cost can be reduced.

  In addition, according to the present invention, dust is generated during handling such as transportation and storage by premixing fluid coke and modified asphalt that has been previously oxidized and / or added with additives to increase the softening point. Thus, there is an effect that handling as a raw material for iron-making coke becomes easy.

  The fluid coke used in the present invention preferably has a grade as shown in Table 1, and has a feature that it has a smaller volatile content than other petroleum cokes and a corresponding amount of fixed carbon. In addition, the particle size of this fluid coke occupies most of about 5mm or less, the crystal structure is inferior, it is a fine powder in a free-flowing state, and it is easy to scatter during storage and transportation, so handling is necessary. It is. Therefore, in order to use such fluid coke as a raw material for coke for steel making, it is molded to have an average particle size of about 20 to 40 mm so that it will not be scattered or spilled by wind and rain when stored in an outdoor raw material yard. It is preferable to use it.

In view of the above-described characteristics of fluid coke, in the present invention, in order to use this fluid coke as a raw material for coke for iron making, it was decided to add asphalt together. In general, asphalt is produced as a vacuum residue after collecting a vacuum gas oil and a lubricating oil fraction from a heavy residue oil generated by a vacuum distillation apparatus in a normal oil refining process. It is a semi-solid substance that is sticky at room temperature with a softening point of about 30 to 60 ° C.
In the present invention, as the asphalt used in combination with fluid coke, it is desirable to use a material having a penetration of 5 or less, a softening point of 100 ° C. or more, and a penetration index of 2 or more. If these properties are not satisfied, it may be too soft and weld during storage.

In the present invention, the mixing ratio of fluid coke and asphalt is preferably added to the blended raw material by mixing 50 to 150 parts by weight of asphalt with 100 parts by weight of fluid coke. The reason is that if the mixing ratio of asphalt is less than 50 parts by mass, the effect of improving the coke strength will be insufficient. On the other hand, if it exceeds 150 parts by mass, the cohesiveness of asphalt and coal will be excessive, resulting in a uniform blended raw material. This is because proper mixing becomes difficult. These preferable compounding ratios are 50 mass parts-150 mass parts.
These ratios may be mixed at substantially the same ratio even when modified asphalt is used as asphalt.

By the way, when this asphalt and fluid coke are mixed, fine coke (<4.75 mm, −74 μm = 95% by mass) is covered with sticky asphalt and bonded together to form large agglomerated particles and It becomes a pseudo particle and is effective in preventing scattering during storage and transportation. Moreover, it is effective in improving the strength of product coke obtained when these mixtures are used as a raw material for coke for iron making.
However, the combination of fluid coke and general asphalt that is not a product of the present invention as defined in JIS K2207, the asphalt is too sticky and has an average particle size of about 20 to 40 mm. Molding may be difficult and may hinder subsequent handling.

  Therefore, the inventors decided to use modified asphalt having a penetration of 5 or less and a softening point of 100 ° C. or more for fluid coke as one preferred embodiment. Therefore, the characteristics of these mixtures were examined below.

  That is, the compounding raw material for coke production used in the coke oven is a solid / granular substance of about 20 mm or less. The blended raw materials are usually transported by ship from overseas, unloaded to a storage yard, and then transported to a coke oven by a belt conveyor. Therefore, when asphalt having general properties is added to such a blended raw material, uniform mixing with coal may be difficult. Therefore, the inventors have roughly mixed the asphalt mixed with fluid coke by oxidizing or thermal polymerization and / or premixing additives such as waste plastic, high softening point pitch, and carbon black. We have developed a technology that uses the modified asphalt, which has been improved to a low fluidity substance in a solid state at room temperature, as a raw material for coke production by raising these softening points.

  That is, the present invention uses a pre-solidified asphalt which is a sticky semi-solid substance at room temperature by chemical treatment. In order to bring the asphalt into a solidified state at room temperature, it is only necessary to raise the softening point of the asphalt, and as one means for that, in the present invention, an oxidation treatment is performed. For example, the raw material heavy oil is heated to about 200 to 300 ° C. and blown in air to oxidize hydrocarbons in the raw material and further polymerize / condense the polymer to produce asphalt It raises the softening point. In addition, in order to obtain modified asphalt, after heating raw material heavy oil, as a modifier for promoting the above reaction, if fluid coke and / or waste plastics are added in advance, the above solidification The reaction time can be further shortened.

  As described above, the present invention is a technique that uses fluid coke as one of the blended raw materials used for the production of iron-making coke, but this fluid coke has a large fine particle size of 5 mm or less. In addition, it is difficult to store in the raw material yard, but there is also an advantage that the transportation thereof becomes easy by adding the modified asphalt to the material yard beforehand. Further, in the present invention, when waste plastic is used as an additive in the production of modified asphalt, the waste plastic treatment, which increases year by year and becomes a social problem, can be effectively used.

  This example describes the results of the dry distillation test of the blended raw material, and this test was performed using a small dry distillation furnace that can simulate an actual coke oven. Samples of blended raw materials are those of the usual blended coal grade (Ro: 1.075, MF: 300) as a base, and additives are added to the sample in the blending ratio shown in Table 2 and mixed uniformly. The product was subjected to a dry distillation test. In Example 2, modified asphalt that was previously mixed with fluid coke and modified was used. The iron coke produced by each dry distillation test was measured for drum strength (DI 150/15) in the rotational strength test method and listed in Table 2.

  From the above test results, the drum strength is reduced in Example 1. In Example 2, it was found that the drum strength was higher than that of the base by using a fluid coke and modified asphalt which were subjected to an equivalent mixing and then subjected to a modification treatment. In addition, the asphalt reforming treatment in Example 2 was performed by heating a vacuum distillation residue oil having a softening point of 51 ° C. and a viscosity of 100 mPa · s at 180 ° C. to 300 ° C. and then blowing air at 40 L / h / kg for 9 hours. It has been processed.

  The technology of the present invention can be used not only in the field of manufacturing coke for iron making such as a blast furnace, but also in the field of pavement manufacturing.

Claims (5)

A method for producing coke for iron making, wherein fluid coke and asphalt are used as part of the blended raw material when carbonized coal is carbonized in a coke oven to produce iron coke. The method for producing coke for iron making according to claim 1, wherein 50 to 150 parts by mass of asphalt are used with respect to 100 parts by mass of fluid coke. First, 50 to 150 parts by mass of asphalt is mixed with 100 parts by mass of fluid coke, and then the mixture is mixed with other compounding raw materials and then pulverized. A method for producing coke for iron making according to 1 or 2. The method for producing coke for iron making according to any one of claims 1 to 3, wherein the asphalt is a modified asphalt made of an oxide and / or an additive added with a softening point adjusted. A raw material for coke for iron making, comprising 100 parts by mass of fluid coke and 50 to 150 parts by mass of modified asphalt modified by adding an oxidation treatment and / or an additive.