JP5614309B2 - Steel blend for coke raw material, steel coke, and method for producing iron coke - Google Patents

Description

  The present invention relates to a coal blend for carbonizing coal (mixed coal) in a coke oven to produce iron-making coke, a coke produced from the blended coal, and a method for producing coke using the blended coal.

  Coke used as a raw material for steelmaking is produced by dry distillation of coal (usually a blended coal containing multiple types of coal) in a chamber-type coke oven. When the thermal stress generated with the shrinkage after resolidification exceeds the substrate strength, cracks are generated, and thereby the particle size of the coke to be generated (coke particle size) is determined. Therefore, in order to increase the coke particle size, it is necessary to reduce the thermal stress or increase the substrate strength.

  In order to lower the thermal stress, methods are known in which the coke oven wall temperature is lowered, the operating rate of the coke oven is lowered, or powdered coke is added to the raw coal. However, there is a problem that a decrease in the furnace wall temperature or a reduction in the operating rate of the coke oven results in a decrease in productivity, and the addition of powdered coke or the like causes a decrease in strength. Moreover, in order to increase the substrate strength, it is necessary to mix expensive caking coal with the raw material coal, but there is a concern that the clearance will decrease due to an increase in the expansion pressure of the coal, resulting in a decrease in productivity due to clogging. Cost increase is a problem. The clearance is the distance between the furnace wall and the coke cake after the coal carbonization, and the larger the clearance, the better the extrudability of the coke cake, so that there is less occurrence of clogging of the kiln and stable operation becomes possible.

  Therefore, a coke production method in which carbon fiber is added to coal (mixed coal) and carbonized is known as a technique aimed at increasing the coke particle size and improving the coke strength. As carbon fiber, there is a case of adding a long fiber (for example, see Patent Document 1) and a case of adding a short fiber (for example, see Patent Document 2). Furthermore, a technique for adding bundled carbon fibers is also known (see, for example, Patent Document 3). In addition, a technique of adding carbon fiber for improving coke extrudability is also known (see, for example, Patent Document 4).

JP-A-4-258690 JP-A-2-235990 JP 2006-273895 A JP 2008-50516 A JP 2003-96466 A

  The example of Patent Document 1 describes that coke strength is maintained when coke is produced by adding carbon long fiber (carbon fiber: 20 μmφ × 20 mm) to blended coal at an addition rate of 1%. However, since carbon fiber does not soften and melt during carbonization, it is presumed that when 1% is added by a normal method, the coke strength decreases due to insufficient fusion between coal and carbon fiber. That is, the addition of long carbon fibers can improve the coke particle size without impairing the coke strength, which is considered to be a special case where carbon fibers are separated as much as possible and sufficiently dispersed and added. Carbon long fibers are generally manufactured by bundling single fibers (filaments) with adhesives, etc., and it is difficult to separate them one by one. Absent.

  On the other hand, in the case of the short carbon fiber disclosed in Patent Document 2 and the like, it is considered that the short fiber obtained by chopping the long fiber produced by usually spinning and firing is used. In such a case, the shape of the fiber is almost straight and short, and since the surface is inactive because of high-temperature treatment, the carbon fiber tends to come off from coke. Therefore, the improvement range of coke strength is small, and improvement in particle size and clearance cannot be expected so much.

  Patent Document 3 discloses suitable carbon fiber conditions when carbon fibers are added in bundles. However, this method has the problem that the carbon fiber must be adjusted to a suitable state, and the strength improvement effect decreases as the amount of carbon fiber added increases.

  Patent Document 4 discloses a technique for improving the dispersibility of carbon fiber by removing the sizing agent of the carbon fiber. However, this technique still requires a complicated treatment, and this technique exclusively improves the extrudability of coke. This is a technique for improvement, and the improvement effect of coke strength is not considered.

  The present invention has been made in view of such circumstances, and when a carbon-containing fiber is added to coal to produce coke, the fiber has a higher strength than conventional without performing complicated processing on the fiber. An object of the present invention is to provide a coke having a large diameter that can be produced with improved clearance, and to provide a blended coal for raw material for iron-making coke, iron-making coke, and iron-making coke.

The features of the present invention for solving such problems are as follows.
(1) A steelmaking coke blended charcoal characterized in that fibers containing keratin are mixed.
(2) The mixed coal for iron making coke according to (1), wherein fibers containing biologically derived keratin are mixed.
(3) The blended coal for iron-making coke according to (1) or (2), wherein carbonized at least part of the fiber containing keratin is mixed by heating.
(4) The mixed coal for iron-making coke according to (2) or (3), wherein the fiber containing biologically derived keratin is a feather and / or feather of birds.
(5) Iron-manufactured coke obtained by dry distillation of the coal-mixed coal for iron-making coke according to any one of (1) to (4).
(6) A method for producing a steelmaking coke, characterized in that the coal blend for ironmaking coke according to any one of (1) to (4) is dry-distilled using a chamber furnace type coke oven.

  According to the present invention, coke having a large particle size can be produced with improved coke strength in the production of iron coke. In addition, since the clearance in the coke oven can be improved, it is possible to avoid the occurrence of operational troubles due to coke stoppage and to continue stable coke operation.

It is a SEM photograph of carbon fiber obtained by firing chicken wings in a natural state (the distance between both ends of the 11 dots at the lower right in the figure is 50 μm). FIG. 2 is a partially enlarged photograph of FIG. 1 (the interval between both ends of 11 points at the lower right in the figure is 10 μm). It is a graph which shows the change of the coke intensity | strength and coke average particle diameter which were obtained by dry-distilling the combination charcoal which added the chicken wing | blade (including the case where a wing | blade of a chicken is baked). It is a graph which shows the change of the clearance at the time of dry-distilling the combination charcoal which added the feather | wing of chicken (including the case where a feather | wing of a chicken is baked).

  As a result of intensive investigation and examination of addition of carbon-containing fibers to blended coal, the present inventors have found fibers that are unlikely to be pulled out from the produced coke even if they are short fibers. The present invention has been completed by discovering that coke is produced by adding and dry-distilling fiber to blended coal to improve the coke particle size, coke strength, and clearance.

  The fiber used by mixing with the blended coal in the present invention is a fiber containing keratin. Keratin, which is a thermosetting protein, does not melt even during high-temperature firing, and can be carbonized while maintaining its shape. Since the fiber containing keratin, which is a thermosetting protein, contains a disulfide bond (-SS-bond), some carbon and / or hydrocarbons (including carbohydrates) are contained when the sulfur is released. Since the carbon constituting the coke is cross-linked (bonded), the fibers are difficult to come out, and even the short fibers are not easily pulled out from the produced coke. If fibers containing keratin having a large aspect ratio (fiber length / fiber diameter) are used, pull-out is less likely to occur. In the present invention, coke is produced by dry-distilling coal-mixed coal for iron-making coke, which is an iron-making coke raw material coal obtained by adding fibers containing keratin, which is a thermosetting protein, to blended coal. When fiber containing keratin is mixed with coal for coke production and carbonized in a coke oven, coke containing carbon fiber is generated.

  As the fiber containing keratin, it is preferable to use a fiber containing biologically derived keratin. Examples of the fiber containing keratin derived from organisms include feathers of egg-laying chickens and meat chickens, and these are generated in large quantities as waste. Therefore, by using the fiber containing biologically derived keratin, the waste can be effectively used and the present invention can be implemented at low cost.

The fiber containing keratin, which is a thermosetting protein, can be added as it is to the steelmaking coke blending charcoal, but it is preferable to use one that has been preheated and carbonized. When the fiber containing keratin is heated, components other than carbon and inorganic substances are released and carbonized, and at that time, part of the carbon is released as CO and CO ₂ , so that the volume of the fiber containing keratin can be reduced. . When the fiber containing keratin is baked at 400 to 600 ° C., the degree of carbonization increases and the bulk can be effectively reduced. Firing of the fiber containing keratin can be performed as multi-stage firing in a plurality of times. Since it can be mixed with blended charcoal with good dispersibility by reducing the bulk, it is preferable to use a state in which 50% by mass or more of carbon components including keratin are carbonized. It is particularly preferable that the fiber containing keratin is sufficiently carbonized and added as carbon fiber. The carbon fiber generally refers to a fiber made almost entirely of carbon, but in the present invention, it refers to a fiber having a carbon content of 90% by mass or more. It is also possible to mix and use keratin-containing fibers that are not carbonized and keratin-containing fibers that are at least partially carbonized.

  The thinner the fibers containing keratin, the better. When the fiber containing keratin is used as it is or after being carbonized, it is mixed with coal for coke production and carbonized in a coke oven to produce coke containing carbon fiber. At this time, the longer the carbon fiber and the smaller the diameter (the larger the aspect ratio), the lower the shear stress at the interface between the coke and the carbon fiber, and the more difficult it is for the carbon fiber to escape from the coke. In order to obtain a sufficient strength improvement effect, the diameter of the single fiber is preferably 0.1 mm or less. Particularly preferably, it is 50 μm or less. When such fibers are carbonized, carbonization occurs while maintaining the original shape, and carbon fibers are produced.

  A fiber containing keratin is preferable if the fiber is not straight, because it is more difficult to escape from coke. “Non-straight” means that the fiber is curved and has a two-dimensional or three-dimensional shape. For example, a “shi” shape, a “ku” shape, a spiral In addition to the case of a shape or a combination thereof, the case where the fiber diameter is not uniform is also included. Some of the fibers are thick, that is, those having a structure with nodes are also not straight fibers, and fibers having such nodes are particularly preferred because they are more difficult to escape from coke. .

  Examples of fibers containing biologically derived keratin include feathers, feathers, wool, hair and the like. These tissues are mainly composed of a fibrous protein called keratin, which has disulfide bonds (-SS-linkages) and forms cross-links between protein molecules or within molecules, that is, a large amount of- Since it is a huge network structure having SS-bonds, it is presumed that the strength of the carbon fiber obtained despite the fact that it is derived from organisms becomes stronger when it is converted to carbon fiber by heating and baking. Feathers, feathers, wool, hair, etc. contain carbohydrates (including hot-melt proteins) and inorganic substances such as P and K in addition to keratin, but the amount added to the blended charcoal is about 5% by mass or less. If present, it will not adversely affect coke quality.

  On the other hand, a fiber containing a biologically derived keratin protein can also be artificially produced. That is, keratin proteins such as feathers and feathers of birds and animal hairs of mammals are extracted by temporarily cleaving the cross-linking bond (disulfide bond) by reduction reaction to form a solution, and regenerating the cross-linking bond by oxidation reaction. Solution spinning may be used to obtain a new artificial keratin fiber. In addition, it is also possible to use a biological material containing keratin that becomes fibrous when carbonized in advance or when the added coal blend is dry-distilled.

  In order to achieve the effect of the present invention, a fiber containing keratin may be used. However, a fiber having a keratin content of less than 1% by mass may not provide a sufficient strength improvement effect. When the fiber to be added contains 50% by mass or more of keratin, the shape retention effect during high-temperature firing is high, which is preferable, and there is no problem even if the content of keratin in the fiber is 100% by mass. Keratin is a well-known analytical method, for example, after processing a sample with a hot organic solvent and hot water, removing the coexisting protein with a proteolytic enzyme to leave keratin, and then observing an X-ray diffraction image, etc. Can be analyzed.

  The part other than keratin of the fiber containing keratin preferably contains carbon as a main component. Hydrocarbons and carbohydrates are carbonized by high-temperature firing. Even if the fiber containing keratin contains an inorganic substance, the influence on coke quality can be reduced by adjusting the mixing amount into the blended coal. When using a fiber containing keratin derived from a living organism, the presence of an inorganic substance does not become a problem as described above.

  When carbon fiber containing keratin or carbon fiber produced by carbonizing keratin in advance is added to coal for coke production and dry-distilled, the coke particle size produced increases, but the better the fiber dispersion, The enlargement rate of the particle size increases. This is because if the fiber is poorly dispersed, the fibers become agglomerated or bundled, the adhesion between the carbon fiber and the coal softening melt is reduced, and the carbon fiber is separated from the coke as the cracks propagate in the coke mass. It is assumed that it is easy to come off. Therefore, the length of the fiber is preferably about several times the particle size of the coal or less in consideration of the miscibility (dispersibility) with the coal. That is, since coal is usually pulverized to a particle size of about 3 mm, the length of the fiber is preferably about 10 mm or less. On the other hand, if the thickness is less than 0.3 mm, the reinforcing effect is reduced, so that the thickness is preferably 0.3 mm or more.

  When the fiber containing keratin is previously carbonized by firing or the like and added to the coal as carbon fiber, it is preferably carbonized in an inert gas atmosphere or a reducing gas atmosphere. Chicken feathers are bent straight or partly thick, so even if they are in a natural state without prior processing, they are not straight if baked (carbonized) at a temperature of 400 ° C or higher. A good carbon fiber can be obtained. However, in the case of wool, hair, etc., if it is baked as it is, it becomes easy to form a straight fiber. Since carbon fiber is obtained, it is preferable.

  On the other hand, surface treatment can also be applied to fibers containing keratin or carbon fibers produced from fibers containing keratin. Although the effect of the present invention is manifested even if no special surface treatment is applied, when the acid treatment is performed with sulfuric acid, nitric acid or the like, the carbonization yield is increased as a result of forming further crosslinks within and / or between the molecules constituting the fiber. A surface treatment may be performed since the shrinkage rate decreases and the amount of fiber added can be reduced as the number increases. In addition, when the fiber is immersed in coal tar / petroleum heavy oil or the like and coal tar or petroleum heavy oil or the like is adhered to the surface of the fiber, the familiarity with coal is improved. Alternatively, when a fiber containing keratin is coated with pitch, asphalt or the like and then converted into carbon fiber, the fiber diameter is increased and the coke strength is increased.

  The addition rate of the fiber to the coal for coke production (mixed coal) is preferably 0.03% by mass or more and 3% by mass or less, and 0.1% by mass or more. 1 mass% or less is especially preferable. If the addition rate is 0.03% by mass or more, the coke strength is improved, and the clearance becomes more than conventional. If the carbon fiber addition rate exceeds 3% by mass, the effect of improving the coke strength tends to decrease. Also, the appearance of the coke cake is more stable without collapse when the carbon fiber is added. This is considered because carbon fiber bridge | crosslinks the inside of a coke cake, and it is guessed that this contributes to the improvement of clearance. Therefore, it is preferable that the addition rate as a carbon fiber shall be 0.03 mass% or more and 3 mass% or less.

  On the other hand, when the fiber containing keratin is not carbonized, that is, when it is added in a state where it is not a carbon fiber, it is preferable to determine the addition amount in consideration of the carbonization yield. For example, since the carbonization yield of chicken wings is 10% by mass or more, in order to add carbon fiber equivalent to 0.03% by mass or more, the fiber before carbonization must be added by 0.3% by mass or more. Therefore, about 0.3% by mass to 30% by mass is preferable. However, in practice, the upper limit of the amount of fiber added is preferably about 12% by mass. This is because the dispersion state deteriorates when the addition amount exceeds 12% by mass. Eventually, when the fiber containing keratin is bird feathers and / or feathers, the addition rate in the state of feathers and / or feathers is preferably 0.3% by mass to 12% by mass. Therefore, when it is desired to set an addition rate exceeding 12% by mass, it is desirable to perform preliminary firing in an inert gas atmosphere or a reducing gas atmosphere to reduce the amount of feathers and / or feathers.

  Chicken fibers, feathers, wool, animal hair, and hair were examined as fibers containing biologically derived keratin. When each keratin content was analyzed, it was about chicken feather: about 90 mass%, feather: about 90 mass%, wool: about 80 mass%, animal hair and hair: 80-90 mass%.

  A coke production test was performed, in which the feathers of meat and egg-laying hens containing keratin were added to the blended charcoal and subjected to dry distillation using a chamber furnace type coke oven. The coking coal used in the test was a coal with an average maximum reflectance of 1.02%, a Gieseler maximum fluidity of 196 ddpm, and a total inert amount of 31.1% by volume. Coal analysis was performed according to JISM8801 and JISM8816.

The chicken wings were heated to 500 ° C. in an inert gas atmosphere and pre-baked (carbon fiber was formed at this stage). An electron micrograph of the fiber in this state is shown in FIG. FIG. 2 shows an enlarged photograph of a part of FIG. According to FIGS. 1 and 2, this fiber has a diameter of 2 to 3 μm and is not a straight fiber but a fiber having a bent portion with a radius of curvature of 1 mm or less. Furthermore, a part of the diameter is seen in the fiber, and a node-like part that is about twice as thick as the other part is seen. In the coke production test, pre-baked chicken wings were crushed to about 3 to 5 mm. The addition ratio of the blade-derived carbon fibers to the blended coal was 1% by mass, and the blended coal was dry-distilled. The coke strength was drum strength (DI ¹⁵⁰ ₁₅ ). DI ¹⁵⁰ ₁₅ is the drum strength obtained by measuring the mass ratio of coke having a particle size of 15 mm or more under the conditions of 15 rpm and 150 revolutions according to the rotational strength test method of JIS K2151.

The measurement results of coke strength (DI ¹⁵⁰ ₁₅ ) and average particle size are shown in FIG. 3 in comparison with the measurement results of coke produced without addition of chicken wings. According to FIG. 3, when carbon fiber is added, it turns out that the intensity | strength of coke is high and the average particle diameter is large. FIG. 4 shows the clearance measurement results. The clearance was measured by the method disclosed in Patent Document 5. It can be seen from FIG. 4 that the clearance is widened, and it is clear that there is an effect of adding the blades of meat chicken and egg-laying chicken to the improvement of the strength of coke, the increase of the average particle diameter and the clearance clearance.

Coke was produced using the same method as in Example 1 except that 5% by mass of the chicken wings was added to the blended coal without pre-baking treatment. As a result, the coke strength (DI ¹⁵⁰ ₁₅ ) was 83.5, the average particle size was 40.3 mm, and the clearance was 13.0 mm. The results are shown in FIGS.

  Since the amount added as carbon fiber is small compared to Example 1 (corresponding to about half the amount), the effect is smaller than the case of “addition of 1% by mass of pre-baked chicken wings” in Example 1, but the chicken wings as they are, It was confirmed that the same effect can be obtained even if the fibers are added in a state where the carbonization treatment is not performed.

Claims (6)

  Coal blend for iron-making coke, characterized in that fibers containing keratin are mixed.   The mixed coal for iron-making coke according to claim 1, wherein fibers containing biologically derived keratin are mixed.   The blended coal for iron-making coke according to claim 1 or 2, wherein a mixture of carbonized fibers containing at least a part of the keratin by heating is mixed.   4. The steelmaking coke blend coal according to claim 2 or 3, wherein the fiber containing biologically derived keratin is bird feathers and / or feathers.   The iron-making coke obtained by dry-distilling the coal-coal for iron-making cokes as described in any one of Claims 1 thru | or 4.   A method for producing iron-made coke, comprising dry-blending the blended coal for iron-making coke according to any one of claims 1 to 4 using a chamber furnace type coke oven.