JP5437280B2 - Method for reforming low-rank coal and method for producing coke - Google Patents

Description

  The present invention relates to a method for reforming low-coalizing coal and a method for producing coke. Specifically, non-caking coal or slightly caking coal classified as low-coalizing coal is used as coke for iron making. The present invention relates to a technique for reforming to a caking coal equivalent that can be used as a raw material during production. The low-coalification coal reforming technology of the present invention can achieve effective use of resources with more energy saving.

  Coke for iron making is produced as a bulk coke by softening and melting coal in the coke oven in the process of heat treatment up to a temperature of 1,000 ° C. or higher where coking is possible. The caking coal belonging to is used. However, the amount of caking coal produced is smaller in absolute amount than non-caking coal or slightly caking coal classified as low-coalizing coal (collectively these are non-caking coal), and In recent years, caking coal suitable for the production of coke has become expensive and difficult to obtain because of its low yield. According to the definition of JIS M 0104 (coal utilization technical term), caking coal is coal that shows caking properties in classification according to the properties of coal. Moreover, the slightly caking coal is coal which shows slightly caking property, and non-caking coal is coal which does not show caking property. Although it is difficult to classify coal clearly because it is a natural product, attempts have been made to numerically specify the range of coal that is normally treated as non-coking coal. For example, coal reflectance (Ro) and maximum fluidity (MF) measured values within the range surrounded by diagonal lines shown in FIG. In use, this figure is often used. Similarly, a coal evaluation diagram called MOF diagram (see FIG. 4) is known in which the properties of coal are displayed by the maximum fluidity and average reflectance (coalization degree), and the tendency by production area is shown. By using this MOF diagram, it is also evaluated whether or not it can be used as a coke raw material from the measured values of the maximum fluidity and average reflectance (coalization degree) of the target coal. The non-slightly caking coal in this invention shall mean the range enclosed with the oblique line shown in FIG. That is, the range of b where Ro <0.85 and MF <2.5 determined by the average reflectance (Ro) indicating the degree of coalification and the maximum fluidity (MF; logddpm), and Ro > 0.85 and both ranges of a range where MF <0.5. The low-rank coal in the present invention means the range of b among these.

  As mentioned above, caking coal is expensive and difficult to obtain, while non-minor caking coal has a higher production volume than caking coal worldwide and is cheaper than caking coal. it can. For this reason, research on reforming non-slightly caking coal to caking coal equivalent has been advanced, and many proposals have been made so far.

  Regarding the technology for converting low-carbonized coal to caking coal equivalent, tar and pitch are added as caking material when using non-slightly caking coal that is inferior in caking properties in coking coal. Various proposals have been made (see Patent Document 1 and Patent Document 2). In addition, according to a method called a coal molding method, powdered low-coalizing coal is briquetted with tar pitch as a caking material and charged into a coke oven together with raw coal (caking coal). Since the coking property is greatly improved, the ratio of coking coal charged into the coke oven can be reduced. Further, in Non-Patent Document 1, non-caking coal is obtained by adding a special caking material (called ASP) obtained by heat-treating asphalt under special conditions to non-caking coal. Says that it can be modified to a high-quality strong caking coal. Furthermore, in Non-Patent Document 1, ASP is not just a substitute for pitch, but is a modifying material having a unique modifying property for non-coking coal, and by using this, the reforming effect and the molding effect are improved. It is said that a synergistic effect can be obtained. In addition, in the above-described technique, a briquette (molded product) of about 40 mm is made with wet coal (water content of about 10%) with a normal coal powder particle size (-3 mm) charged in the coke oven, Charging is done.

  In recent years, a method for modifying non-coking coal, which has a different concept from the coal casting method described above, has appeared. This is a system called SCOPE21 jointly developed by the Coal Utilization Center and the Japan Iron and Steel Federation, but the basis of this technology is to rapidly heat non-coking coal powder. It is used to make it tangible. The SCOPE21 process can increase the usage ratio of non-slightly caking coal relative to raw coal compared to a normal coke oven, and at the same time has the characteristics of high productivity, environmental improvement, and energy saving (non-patented) Reference 2).

JP 2000-8047 A JP 2004-307557 A

Journal of Fuel Association, Vol.56, No.607,886-897 (1977). Journal of the Japan Institute of Energy, Vol.84, No.3, 170-176 (2005).

  However, none of the conventional reforming technologies can produce high-strength coke using only the modified non-caking coal as a raw material. In the reports published so far, it is said that the coke raw material is at most 20-50% non-slightly caking coal, and the ratio is actually lower. Moreover, since the above-mentioned ASP used as a modifier of non-slightly caking coal is a petroleum product obtained by heat-treating residual residual oil by-produced in petroleum refining with superheated steam (500 to 700 ° C.). In addition to the problem of high price, there is a problem to be solved from the viewpoint of energy saving, which has become a big problem in recent years. Thus, the effective use of non-slightly caking coal in coke production is a long-standing issue, but it is difficult to say that it is still an established technology. In addition, there are problems such as resource depletion, environmental conservation, and energy saving (reduction of carbon dioxide generation).

  Therefore, the object of the present invention is to convert a non-coking coal classified as a low-coalizing coal into a coking coal equivalent that can be used as a raw material in the production of coke for iron making and the like. It is an object of the present invention to provide a reforming method. Another object of the present invention is that a modified low-coalized coal can be applied at a high use ratio as a raw material for producing coke, and when applied, the quality is equivalent to that of coke made from caking coal. It is another object of the present invention to provide a method for producing coke that can contribute to energy saving.

The above object is achieved by the present invention described below. That is, the present invention is a method for reforming low-carbonized coal for converting low-carbonized coal to caking coal equivalent, which is a powdered low-carbonized coal, petroleum-based or coal-based At least a reforming step for reforming by heating at a temperature of 350 ° C. to 450 ° C. in a state where the reformer is coexisting, and the above-mentioned petroleum-based or coal-based modifier has a softening point of 200 ° C. Below 80 ° C., heavy oil with quinoline insoluble content of 10% by mass or less, aromatic carbon index fa value of 0.3 or more, and the use ratio is the above-mentioned low coal degree coal and the above modified coal The ratio with respect to the mass material is 97: 3 to 60:40 on a mass basis, and among those classified as non-slightly caking coal as the low -rank coal, the average reflectance (Ro) is Ro <0. 85, and maximum fluidity degree; a (MF logddpm) is MF <2.5, further measurement of the maceral analysis of coal The ratio of the active moiety which are determined by the law is a method of modifying a low coalification degree coal characterized that you selected in excess of 50%.

The following are mentioned as a preferable form of the reforming method of the low coal degree coal of this invention. The low coalification degree charcoal method for modifying a low coalification degree coal Ru der those less than 2% moisture. A method for reforming low-carbonized coal, wherein the ratio of the active portion of the low-carbonized coal exceeds 60%. A method for reforming low-coalification coal, in which the powdery low-coalification coal and petroleum-based or coal-based reforming material are mixed and coexisted . Upper SL low coalification degree coal, 2% moisture or less, which has been dried and ground to a particle size of less than 1 mm, and, a powder-like low-coalification degree coal and petroleum or coal-based modifying material A method for reforming low-coalizing coal comprising mixing, molding the mixture into a predetermined shape to obtain a molded product, and heating the molded product at a temperature of 350 ° C to 450 ° C.

Another embodiment of the present invention is a method for producing coke using caking coal equivalent obtained by reforming low-coalification coal as at least a part of a coke raw material, which is a powdery low-coalization degree It has a charcoal, a modifying step of modifying the petroleum or by heating at a temperature of 350 ° C. to 450 ° C. in a state in which coexist a modifier of coal-based low coalification degree coal, the petroleum or The coal-based modifier is a heavy oil having a softening point of 200 ° C. or less and 80 ° C. or more, a quinoline insoluble content of 10% by mass or less, and an aromatic carbon index fa value of 0.3 or more, and Although the usage ratio is 97: 3 to 60:40 on a mass basis, the ratio of the low- carbonized coal and the modifier is classified as non- coking coal as the low -carbonized coal. Of these, the average reflectance (Ro) is Ro <0.85, and the maximum fluidity (MF; logddpm) is MF <2.5. There further proportion of the active moiety which are determined by the measuring method of the maceral analysis of coal is coke production method which is characterized that you selected in excess of 50%.

The following are mentioned as a preferable form of the manufacturing method of the coke of this invention. The low coalification degree charcoal method moisture less than 2% of what der Ru coke. A method for producing coke, wherein the ratio of the active portion of the low-carbonized coal exceeds 60%. The low coal content coal is dried and pulverized to a moisture content of 2% or less and a particle size of 1 mm or less, and the powdery low coal content coal is mixed with a petroleum-based or coal-based modifier. A method for producing coke, wherein a product is molded into a predetermined shape to obtain a molded product, and the molded product is heated at a temperature of 350 ° C to 450 ° C.

  ADVANTAGE OF THE INVENTION According to this invention, the reforming method of the low coalification degree coal which converts efficiently low coalification degree coal into the caking coal equivalent which can be used as a raw material in manufacture of coke for iron manufacture etc. is provided. In addition, according to the present invention, the modified low-coalizing coal can be applied at a high use ratio as a raw material for producing coke, and when applied, coke having a quality equivalent to that of coke using caking coal as a raw material. Further, a method for producing coke having an extremely high industrial value that can contribute to energy saving is provided.

It is a schematic block diagram at the time of industrializing the coke manufacturing method of this invention. It is a schematic block diagram which shows an example to which the pelletizing method which shape | molds a briquette is applied. It is a figure which shows the range of a low coalification degree coal. It is a MOF diagram.

  Hereinafter, the present invention will be described in more detail with reference to preferred embodiments, but an explanation will be given by taking, as an example, non-slightly caking coal classified as low-coalizing coal. The present inventors diligently studied a method for reforming low-coalizing coal to a caking coal equivalent that enables effective use of non-slightly caking coal in coke production, which is a long-standing problem. And the ultimate goal is to improve the non-slightly caking coal to 100% caking coal equivalent, increase the reforming efficiency at that time, deplete resources and save energy (reducing carbon dioxide generation). It also provides reforming technology that takes into account. In order to achieve these objectives, specifically, the selection of low-rank coal that can be efficiently reformed, which is also useful for conventional reformers, and new reforms that are inexpensive and effective. As a result of investigations such as search for materials, reduction of the ratio of use of the reforming material relative to low-coalized coal, and improvement of the reforming speed, the present invention has been achieved.

  First, the inventors of the present invention have been unsatisfied with the performance of the reformer as an ASP that has been conventionally used as a modifier of non-slightly caking coal, and as described above, Because it is a special pitch produced by heat-treating residual residual oil produced as a by-product in petroleum refining with superheated steam (500 ° C to 700 ° C), the price is high and it is also a problem from the viewpoint of energy saving, which has become a big problem in recent years. Focused on the fact that there is. And it examined in order to search for the new modifier which has a high reforming effect and can reduce the cost and energy required for manufacturing. As a result, it has been found that, for example, a high boiling point distillate (heavy oil) containing a residue by-produced in an oil refining process is useful as a modifier for low-degree coal. As a result of further studies, among the by-products, the softening point is 200 ° C. or lower and 80 ° C. or higher, the quinoline insoluble content (hereinafter also referred to as QI component) is 10% by mass or lower, and the aromatic carbon index fa value is 0.3 or higher. It has been found that heavy oils having the following aromatic properties are useful as modifiers for low-rank coal. As an example of heavy oil having such characteristics, there is a residue obtained by extracting asphalt with a solvent such as butane or pentane under high temperature and high pressure, and such heavy oil is particularly a modifier used in the present invention. It is suitable as. Hereinafter, this heavy oil is referred to as SDA pitch. The above heavy oil is obtained as a by-product during petroleum refining, and does not require a special production cost as in the case of the above-described conventional modifier (for example, ASP), and is low in price. Because it shows high reforming performance against coal, it is an extremely effective and very economical petroleum-based reformer when used as a reformer. The amount used for charcoal can be greatly reduced as compared with the conventional one. Details will be described later. In addition, even if the thing of the characteristic similar to the above is obtained, even if it is a coal-type modifier, it can be used.

  Next, the present inventors examined by focusing on the low-rank coal to be reformed. That is, if low-coalizing coal that can be easily reformed can be selected, the reforming efficiency can be improved. As a result, not only when the above-mentioned petroleum-based reforming material SDA pitch newly found by the present inventors is used, but also when ASP or the like used as a reforming material in the prior art is used. As a result, the present inventors have found the characteristics of low-carbonized coal that can be efficiently modified into a caking coal-equivalent product, and have reached the present invention. Specifically, in the method for reforming low-rank coal according to the present invention, the low-rank coal to be reformed has an active portion determined by measurement of coal maceral analysis of 50% or more, more preferably 60%. % Or more is used. The “active part calculated | required by the measurement of the maceral analysis of coal” prescribed | regulated by this invention is a value obtained by measuring based on "the fine structure component of a coal, and the reflectance measuring method JISM8816." That is, the active part as used in the present invention refers to an active ingredient obtained by measurement of coal maceral analysis. More specifically, the active ingredient refers to vitrinite, ecdynite, degrading contained in coal. It is said to mean ingredients such as ready knit. In addition, in the said JIS, the inactive ingredient of the word with respect to an active ingredient is "the inactive ingredient is a micro structure component (maceral) that can be identified by observing coal with a microscope, and is heated by cutting off contact with air. In this case, it is defined as a component that does not soften or melt.

  According to the study by the present inventors, the reforming efficiency can be improved by selecting and using low-carbonized coal having such an active portion of 50% or more, more preferably 60% or more. it can. The present inventors have observed the degree of reforming using various conventional low-grade coals and SDA pitch newly found by the present inventors as a reforming material for various low-coalized coals. Specifically, low-carbonized coal with an active portion of 75% is pulverized, and each modifier is added to dry coal powder of 35 mesh or less, and kneaded. The degree of fluidity was evaluated by the maximum fluidity measured by a Gieseler plastometer. Coal caking and tackiness are usually evaluated by measuring the fluidity using a Gieseller Plastometer [JIS M8801 (Coal testing method)] as a measuring device. The electric furnace used for measurement with a Gisela plastometer is JIS M8801, and is specified as being capable of raising the temperature at a temperature range of 300 ° C. to 500 ° C. at 3.0 ± 0.1 ° C./min. . On the other hand, in the present invention, it is assumed that the low-carbonized coal and the reforming material are kneaded and the admixture is heat-treated at a temperature of 350 ° C. to 450 ° C. for reforming. In the examination in the room, heat treatment was performed in the electric furnace, and at the same time, the fluidity was measured with a Gieseler plastometer.

  The fluidity is usually expressed in units of ddpm (Dial Division per Minute), and the maximum fluidity (MF) is used as the characteristic value of coal. Conventionally, this is often referred to as fluidity, and the common logarithm of ddpm is sometimes used. Usually, caking coal used as coking coal at the time of coke production has a Gieseler plastometer value of 300 ddpm or more, more preferably 1,000 ddpm or more (see FIG. 3). On the other hand, the maximum fluidity of the low-coalizing coal is 0 ddpm in the case of non-caking coal, and is usually several tens ddpm to 100 ddpm, or about 200 to 300 ddpm at the highest in the case of slightly caking coal. However, it would be very useful if such non-slightly caking coal could be modified to caking coal equivalent. For example, if low-carbonized coal can be modified to about 200 to 300 ddpm, it can be used as coke raw material by blending with caking coal, and if it can be further modified to more than 300 ddpm, it has been modified. Only the raw material can be used as coking coal.

  As a result of the above examination, when only the low-carbonized coal before reforming was heat-treated, the maximum fluidity was 28 ddpm, whereas each modifier was reduced to 90% low-carbonized coal on a mass basis. When 10 is added, the maximum fluidity is about 3 times higher when ASP is added than when only low-degree coal is added, and the maximum fluidity is increased when SDA pitch is added. It became 6 times or more and confirmed that all were effective as a modifier. Furthermore, when the addition amount of the modifier is 12.5 with respect to 87.5 low-coalized coal, the one with ASP is the highest compared to the case of low-carbonized coal alone. While the fluidity remained at about 4.5 times, the one with the addition of SDA pitch became a high quality caking coal equivalent with a maximum fluidity of 1,000 ddpm or more. In addition, it was found that if the addition amount of the modifier was further increased, the one with ASP added would be a good quality caking coal equivalent with a maximum fluidity of 1,000 ddpm or more.

  On the other hand, when a similar study was performed using low-coalizing coal with less than 50% active part, the amount of modifier added was increased, and even when the low-coalizing coal 60 was set to 40, it was improved. Even though any modifier was used, the obtained modified coal could not be used as a coke raw material alone, and satisfactory results were not obtained. These facts show that it is effective to have a high active portion when selecting a low-rank coal to be reformed. According to further studies by the present inventors, a high-quality caking coal equivalent that can be used as a coke raw material more efficiently and reliably when an active portion is used in an amount of 50% or more, more preferably 60% or more. Can be modified. Furthermore, if SDA pitch is used as a modifier, in addition to being cheaper than the ASP of the conventional modifier, the amount used can be greatly reduced, so that more economical reform is possible. Therefore, it can be said that it is more preferable industrially.

  In contrast to the above-described present invention, in the prior art, there are descriptions of elemental analysis, industrial analysis, and the like for non-slightly caking coal to be reformed, but there is no provision for other analysis values. This indicates that, in the prior art, regarding the non-coking coal to be reformed, even the knowledge that the proportion of the active part determined by the measurement of the maceral analysis of the coal affects the degree of reforming, It means that it has never been obtained so far. In the present invention, a low-coalization degree coal to be reformed, which has not been considered in the past, is selected by paying attention to the ratio of the active portion determined by the measurement of the maceral analysis. The effect of reforming charcoal to a higher quality caking coal equivalent is made more reliable.

  As described above, examples of coal to be reformed by the method for reforming low-coalification coal of the present invention include non-slightly caking coal having a Gieseler plastometer value smaller than 200 to 300 ddpm. It is done. In terms of the type of coal, the bituminous coal is the one with the lowest degree of coalification and the sub-bituminous coal is the one with the highest degree of coalification. According to the reforming method of low-degree coal of the present invention, for example, even in the case of this value of several ddpm or even non-caking coal of 0 ddpm, as in the case of the examples described later, It can be modified to a high quality caking coal equivalent.

  In the present invention, the selection of the low-carbonized coal to be reformed is performed by defining the ratio of the active portion obtained by the measurement of maceral analysis, and the selected low-carbonized coal is coexisted with the reformer. In this state, reforming is performed by heating at a temperature of 350 ° C. to 450 ° C. As described above, in the present invention, more preferably, an SDA pitch of a petroleum-based modifier is used as the modifier. If it does in this way, in the state which reduced the usage-amount of the modifier, it can modify | reform to the caking coal equivalent goods of good quality extremely efficiently. Hereinafter, the SDA pitch, which is a petroleum-based modifier suitable for the present invention, will be described.

  SDA pitch is obtained as a high-boiling distillate containing a by-product residue in petroleum refining. Among them, preferred modifiers are those having a softening point of 200 ° C. or less and 80 ° C. or more, a QI component of 10% by mass or less, and an aromatic carbon index fa value (hereinafter also simply referred to as fa value) of 0.3 or more. It is a quality oil. More preferable examples include those having an fa value of 0.5 or more and a softening point of 190 ° C. or less, more preferably 180 ° C. or less. Here, the fa value is a value obtained by dividing the number of aromatic carbons by the total number of carbons. In addition, the softening point of the heavy oil used by this invention is a softening point measured by the ring and ball method based on JIS-K2531. The softening point of heavy oil with a high softening point, which is difficult to measure by the ring and ball method, is determined by the softening start temperature in accordance with the fluidity test method of JIS-M8801 (Gieseller plastometer method). The temperature when starting to move and reaching 1.0 ddpm).

  According to the study by the present inventors, as described above, a heavy oil having a high softening point of 80 ° C. or higher is effective when reforming low coal content coal by mixing with low coal content coal. It was found that a higher reforming effect can be obtained by using many reforming components. On the other hand, when the softening point is lower than 80 ° C., the reforming components contained in the heavy oil are evaporated during the heat treatment at 350 ° C. to 450 ° C. in which the reforming is performed in the present invention, and a sufficient reforming effect is obtained. It becomes difficult. On the other hand, if the heat treatment temperature is higher than 450 ° C., the reforming does not proceed. The specific heat treatment temperature may be determined in consideration of the modifier used. For example, when the above-described SDA pitch is used as the reforming material, the low-rank coal is reformed to a caking coal equivalent at a temperature of around 400 ° C.

  Petroleum heavy oils have a wide range of softening points from room temperature to over 200 ° C. For example, those shown in Table 1 are known (Kenji Matsubara dissertation "Evaluation of caking materials for coke raw materials" "Study on" (1989, University of Tokyo)). In the present invention, in Table 1, it is particularly preferable to use a softening point of 200 ° C. or lower, 80 ° C. or higher, a QI component of 10% or lower, and an aromaticity (fa) of 0.3 or higher. It was judged. The SDA pitch and SRC in Table 1 correspond to those having the above characteristics. In the present invention, the SDA pitch will be described as an example.

  In the present invention, the reason why the QI component of heavy oil suitable as a modifier is 10% by mass or less is as follows. In other words, heavy oil with a high QI component is produced by subjecting by-products from petroleum refining processes such as asphalt to secondary treatment such as heating (caking agent), and is produced by this secondary treatment. In addition to the increase in cost, the QI component itself has no reforming ability, and if the QI component exceeds 10%, the necessary reforming effect is reduced. Heavy oil with a high softening point and a large QI component is expensive because it is produced by subjecting heavy oil, which is a by-product of the production process obtained in the normal process, to heat treatment. Thus, not only the cost for reforming, and hence the price of coke, but also the amount of energy used for production increases, which is not preferable from the viewpoint of energy saving.

  In the method for reforming low-carbonized coal of the present invention, when the above-mentioned SDA pitch is used as a modifier and heat-treated in combination with the low-carbonized coal, The mixing ratio is preferably as follows. In this case, as will be described later, the case where the low-coalized coal is used after being dried and the case where it is used in a wet state are strictly different, for example, 97: 3 to 60:40, preferably on a mass basis. Is in the range of 96: 4 to 70:30, more preferably 95: 5 to 90:10. When the mixing ratio of SDA pitch is less than 97: 3, the expression of caking property is insufficient during heat treatment. On the other hand, when the ratio is more than 60:40, improvement of the effect cannot be expected, and a large amount of heavy oil is used. This is not preferable because the economy is impaired. As described above, when SDA pitch is used as the reforming material, for example, it is possible to reform to a high quality caking coal equivalent with a smaller amount of addition than conventional ASP. Economical.

  In the present invention, heat treatment is performed at a temperature of 350 ° C. to 450 ° C. in a state where a low-rank coal having an active portion ratio of more than 50% coexists with a modifier such as petroleum as described above. What is necessary is just to make it coexist and there is no limitation in particular. For example, low-carbonized coal and heavy oil that is a modifier are simply kneaded with a kneader or the like, even if they are placed alternately in the same furnace or lightly mixed into a mixture. The mixture may be in the form of a mixture, but more preferably a sufficiently mixed mixture or kneaded product. As a more preferable embodiment of the method for reforming low coal content of the present invention, the low coal content coal to be reformed is dried and pulverized to a moisture content of 2% or less and a particle size of 1 mm or less. A mixture obtained by adding a kneading agent such as a pitch at a desired ratio and kneading is further formed into a molded product formed into a predetermined shape. When the molded product is used as a briquette, the normal size is 40 mm in major axis, but is 30 mm or less, preferably about 15 to 25 mm, smaller than this. Moreover, when making a molding into a pellet, it is preferable to make the particle size of raw coal into -0.4mm (0.4mm or less), and make the magnitude | size into a spherical shape about 3mm in diameter on average. In addition, the strength of these moldings is such that a predetermined shape can be maintained until the necessary caking properties are produced by the reforming of non-slightly caking coal at a reaction temperature of 350 to 450 ° C. These molded products can be used as coking coal in a coke oven as they are, and as a result, better coke that can be used for iron making can be obtained. Hereinafter, the manufacturing method of the coke of this invention is demonstrated.

  In the method for producing coke of the present invention, coke is produced according to a conventional method using caking coal equivalent obtained by modifying low-coalized coal according to the present invention as at least a part of coke raw material. At that time, it has a reforming step in which it is reformed by heating at a temperature of 350 ° C. to 450 ° C. in a state where a powdery low-coalizing coal and a petroleum-based or coal-based modifying material coexist. The low-coalizing coal needs to have an active part ratio of more than 50% determined by a measuring method of coal maceral analysis. More specifically, a caking coal equivalent product is obtained in the above reforming process, and this is used as a part or all of the raw coal, and heat treatment is performed at a temperature of 1,000 ° C. or higher at which coking occurs, resulting in high quality. Coke can be obtained.

  A more preferable embodiment of the method for producing coke according to the present invention will be described. First, after adding and kneading the low-rank coal with an active portion of 50%, more preferably 60% or more, and the above-mentioned SDA pitch, the mixture is formed into a briquette or pellet as described above, and the molded product is coke. Charge into the furnace. As a result, the briquettes or pellets are heated at a temperature around 400 ° C., and the low-carbonized coal is converted into one corresponding to caking coal. Then, if the obtained caking coal equivalent is heated to a temperature at which coking occurs, high-quality coke with high strength can be obtained. This series of changes will be specifically described. First, the molded product obtained as described above is charged into a coke oven and heated at a rate of 3 ° C./min (in a normal coke oven, heated at a rate of 3 ° C./min). When heated from room temperature, the low-carbonized coal reacts with the SDA pitch described above in the temperature range of 350 to 450 ° C., and the molded product is converted into a caking coal equivalent having caking properties. When the temperature is further increased, gas generation due to thermal decomposition becomes active, and the molded product is deformed or broken due to an increase in the internal pressure of the molded product, but the deformation or breakage at this stage is not a problem at all. As the temperature rises further, the agglomeration progresses and eventually becomes strong coke. In addition, the above-mentioned molded product is good also as what is mixed with the powdery caking coal currently used for manufacture of a normal coke, and is charged in a coke oven.

  The method for producing coke according to the present invention is not limited to the above-mentioned method, and although it is inferior in efficiency and the like, it is not necessarily formed into a molded product, but the active portion has a low coal degree of 50% or more, more preferably 60% or more. It is possible to obtain high-quality coke even when charcoal and petroleum-based reforming materials such as SDA pitch are simply mixed and the above heat treatment is performed. However, in this case, it is necessary to take measures such as increasing the amount of modifying material such as SDA pitch.

  FIG. 1 shows a schematic diagram of an example of industrializing the method for producing coke according to the present invention. In this example, a mixture of low-carbonized coal and a modifier (SDA pitch) is used as a molded product. . Referring to FIG. 1, first, the low-carbonized coal to be reformed is simultaneously dried and pulverized using a dry pulverizer. The obtained pulverized product is collected in a cyclone, transported on a screw conveyor, heated SDA pitch is added, and then sufficiently kneaded in a kneader, and then a briquette having a size of about 20 mm is used in a briquetting apparatus. To manufacture. Next, the obtained briquette is charged into a coke oven and heated. As a result, the briquette low-coalizing coal is reformed to a caking coal equivalent in the process of being heated to 350 ° C. to 450 ° C. in the furnace.

  An example of the pelletizing method for molding the briquette will be described in detail (see FIG. 2). First, the low-carbonized coal is dried and pulverized to a particle size of −0.4 mm (0.4 mm or less) and mixed with SDA pitch. Then, it granulates with a granulator and cools and dries. The granulated product is extracted with an average diameter of 3 mmφ classified by a sieve, and then coated with coke powder to prevent caking. As a result, layered pellets are obtained. After pulverizing the large pellets, the small pellets are circulated as they are, and after passing through the granulation and drying process, enter the sieve. The pellets thus obtained are charged into a coke oven and reformed to a caking coal equivalent, and then heated at a higher temperature to finally become coke.

  Conventionally, raw coal is charged into a coke oven in the state of wet coal (water content of about 10%). On the other hand, when forming into a molded product by the method as described above, the low-carbonized coal was dried to a moisture content of 2% or less, preferably 1% or less, more preferably 0.5% or less. It will be charged into the furnace in the state. For this reason, the amount corresponding to the heat of evaporation of moisture contained in the wet coal is energy-saving. Considering the enormous amount of coal used for iron-making coke, enormous energy-saving can be achieved by adopting the method described above. In addition, since the reaction between the low-carbonized coal and the petroleum-based reforming material such as SDA pitch is exothermic, this is also taken into consideration in terms of energy saving, so that energy saving is achieved. As illustrated in FIG. 1, the energy saving effect can be further improved by effectively using the exhaust gas from the coke oven in the drying step. The exhaust gas from the coke oven has a discharge temperature of about 150 ° C., but is not used at most steelworks and is discharged from the chimney, which is very useful if it can be used effectively.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated concretely, this invention is not limited to these. Unless otherwise specified,% is based on mass.

[Examples 1 to 4 and Comparative Example 1]
As the low-rank coal for reforming, those listed in Table 2 were used. The MF (ddpm) value is a maximum fluidity value measured with a Gieseller Plastometer.

  As the modifier, heavy oil A (SDA pitch) having the following characteristic values was used. That is, the ash content is 0%, the volatile content is 71.0%, the carbon content is 84.0%, the hydrogen content is 8.0%, the softening point is 138 ° C., the QI component is 0%, and the aromatic carbon index is fa. A value of 0.643 was used. Heavy oil A is a residue obtained by solvent extraction of asphalt using light reformate obtained in the petroleum refining process as a solvent.

  10% of heavy oil A was mixed and blended with 90% of each of the characteristics shown in Table 2 and molded at 150 ° C. to obtain 20 g of a disk-shaped molded product of 20 mmΦ × 5 mm. When measuring the maximum fluidity (ddpm) of the obtained molded product with a Gisela plastometer, the temperature condition in the electric furnace is increased to 500 ° C. at a rate of 3 ° C./min. At the same time, the reforming treatment was performed under these conditions. The results are shown in Table 2. It was confirmed that the difference in the active ingredient clearly affects the reforming effect, and that the reforming effect is improved as the proportion of the active ingredient is higher. In particular, it has been found that sufficient reforming is possible when the proportion of the active ingredient is 50% or more, more preferably 60% or more. However, when the proportion of the active ingredient is relatively low, such as 50% to 60%, means for increasing the amount of the modifier added is necessary for more effective modification.

[Reference Examples 5 to 8 and Comparative Example 2]
Using the same types of coal A, coal B, coal C, coal D and coal E as used in Examples 1 to 4 and Comparative Example 1 and heavy oil A, the reforming treatment was performed as follows. Study was carried out. In the case of this reference example, the particle size of the coal was set to -3 mm (3 mm or less), and the moisture content (%) of the coal was 9.9% in the coal A of the reference example 5, and in the coal B of the reference example 6, respectively. 10.0%, Coal C of Reference Example 7 was 11.0%, Coal D of Reference Example 8 was 12.0%, and Coal E of Comparative Example 2 was 13.0%. Each coal was blended at a blending ratio of 90% and heavy oil A at a blending ratio of 10%.

  When each molded product obtained was heated to 350 ° C. at a rate of 3 ° C./min, all the molded products were cracked and the shape of the molded product could not be maintained, and heavy oil A was partially It was confirmed that it was washed out of the molding. As a result, it was predicted that the reaction between coal and heavy oil would not progress much at higher temperatures in these moldings. The present inventors infer that the reason why the shape could not be maintained was caused by the evaporation of moisture because the amount of moisture in the molded product is expected to increase. Since the reaction between heavy oil A and coal is considered to occur in the temperature range of 350 ° C. to 450 ° C., it is expected that the effect of improving fluidity as a result of the reaction will be small in a system with a large amount of water. The In Examples 1 to 4 and Comparative Example 1, cracks and deformation of the molded product did not occur as a result of the temperature increase.

[Example 5 and Comparative Example 3]
Example 1 and Comparative Example 1 except that heavy oil A was replaced with heavy oil B described below using the same types of coal A and coal E used in Example 1 and Comparative Example 1, respectively. The modification treatment was performed in the same manner. The analysis values of the heavy oil B used are as follows. That is, heavy oil B has an ash content of 1.0%, a volatile content of 40.3%, a carbon content of 86.1%, a hydrogen content of 5.9%, a softening point of 193 ° C., and a QI of 14.9. %, The fa value indicating the aromatic carbon index is 0.637.

  About each molded article obtained by performing said process, the maximum fluidity | liquidity was measured with the Giesser plastometer. As a result, coal A was 250 ddpm (Example 5), and coal E was 30 ddpm (Comparative Example 3). However, in comparison with Example 1, it was confirmed that the reforming efficiency was lowered by replacing heavy oil A with heavy oil B having a QI component of 10% or more. This indicates that it is more preferable to use the heavy oil A used in Examples 1 to 4 in order to improve the reforming efficiency.

Claims (9)

A method for reforming low-carbonized coal for converting low-carbonized coal to caking coal equivalent, comprising a powdery low-carbonized coal and a petroleum-based or coal-based modifier. It has at least a reforming step in which it is reformed by heating at a temperature of 350 ° C. to 450 ° C. in the coexisting state, and the above-mentioned petroleum-based or coal-based modifier has a softening point of 200 ° C. or lower, 80 ° C. or higher, It is a heavy oil having an insoluble content of 10% by mass or less and an aromatic carbon index fa value of 0.3 or more, and the use ratio thereof is a ratio of the low-rank coal and the modifier. 97: 3 to 60:40 on a mass basis, and among those classified as non-slightly caking coal as the low -coalizing coal, the average reflectance (Ro) is Ro <0.85, and the highest fluidity (MF; logddpm) is MF <2.5, further determined by the measuring method of the maceral analysis of coal Method of modifying a low coalification degree coal ratio of active moiety characterized that you selected in excess of 50%. The method for reforming low coal content coal according to claim 1, wherein the low coal content coal has a moisture content of 2% or less .   The method for reforming low coal content coal according to claim 1 or 2, wherein the ratio of the active part of the low coal content coal exceeds 60%.   The low coalification degree of any one of Claims 1-3 which makes the state which mixed the said powdery low coalification degree coal and a petroleum-type or coal-type modifier, and made these coexist. Charcoal reforming method. The low-carbonized coal is dried and pulverized to a moisture content of 2% or less and a particle size of 1 mm or less, and the powdery low-carbonized coal is mixed with a petroleum-based or coal-based modifier. and, a molded product by molding該混hydrate into a predetermined shape, molded type was low coalification degree coal according to any one of claims 1 to 4, heating at a temperature of 350 ° C. to 450 ° C. Modification method. A method for producing coke that uses caking coal equivalent obtained by modifying low-coalification coal as at least a part of coke raw material, which is a powdery low-coalification coal, petroleum-based or coal-based It has a reforming step of reforming low- rank coal by heating at a temperature of 350 ° C. to 450 ° C. in the state of coexisting with the reformer, and the above petroleum-based or coal-based reformer is softened It is a heavy oil having a point of 200 ° C. or less and 80 ° C. or more, a quinoline insoluble content of 10% by mass or less, and an aromatic carbon index fa value of 0.3 or more, and its use ratio is the above-mentioned low coalification degree The ratio of charcoal to the above modifier is 97: 3 to 60:40 on a mass basis, and among those classified as non-slightly caking coal as the low -coalizing coal, the average reflectance (Ro) is in ro <0.85, and the maximum fluidity (MF; logddpm) is MF <2.5, further coal Ma Method for producing a coke ratio of the active moiety which are determined by the measuring method of Lal analysis characterized that you selected in excess of 50%. The method for producing coke according to claim 6 , wherein the low-rank coal has a moisture content of 2% or less . The method for producing coke according to claim 6 or 7 , wherein the ratio of the active portion of the low-carbonized coal exceeds 60%. The low-carbonized coal is dried and pulverized to a moisture content of 2% or less and a particle size of 1 mm or less, and the powdery low-carbonized coal is mixed with a petroleum-based or coal-based modifier. The method for producing coke according to any one of claims 6 to 8 , wherein the product is molded into a predetermined shape to obtain a molded product, and the molded product is heated at a temperature of 350 ° C to 450 ° C.

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