Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
  • C10B45/00—Other details
  • C10B45/02—Devices for producing compact unified coal charges outside the oven
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
  • C10B53/00—Destructive distillation, specially adapted for particular solid raw materials or solid raw materials in special form
  • C10B53/08—Destructive distillation, specially adapted for particular solid raw materials or solid raw materials in special form in the form of briquettes, lumps and the like
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
  • C10B57/00—Other carbonising or coking processes; Features of destructive distillation processes in general
  • C10B57/04—Other carbonising or coking processes; Features of destructive distillation processes in general using charges of special composition
  • C10B57/06—Other carbonising or coking processes; Features of destructive distillation processes in general using charges of special composition containing additives

Definitions

• the present invention relates to a method for producing molded coal for coke production and a strength improving material for molded coal.
• Blast furnace coke is used in blast furnaces as a reducing agent, a heat source, and a support material to maintain air permeability and liquid permeability.
• a blast furnace it is necessary to ensure air permeability and liquid permeability inside the furnace, and coke with excellent properties such as strength, particle size, and post-reaction strength is required.
• coke strength such as rotational strength, is a particularly important property.
• the molded coal blending method is a technique in which high-density molded coal is produced by pressurizing and molding coal powder, and the powdered blended coal and the molded coal are charged into the coke oven together, thereby improving the bulk density of the raw materials charged into the coke oven.
• the molded coal used in coke production is usually produced using coal-, petroleum- or organic-based binders (glues) to prevent it from collapsing during transportation. Molded coal that collapses and becomes smaller in volume during transportation is sieved and reused as raw material for molded coal. Therefore, by preventing it from collapsing during transportation, it is expected that the yield of molded coal will improve and the productivity of molded coal will increase.
• the collapse of molded coal during transportation is mainly caused by the impact of dropping it when transferring between conveyors or when it is put into a hopper.
• the collapse caused by the impact of dropping it was the cause of reduced productivity of molded coal.
• conventional coal-, petroleum- and organic-based binders are sticky binders that exert their strength by bonding raw material particles together due to their stickiness.
• problems arise such as raw material sticking to equipment due to the large amount of sticky binder.
• a technology that improves the drop strength of molded coal without increasing the amount of sticky binder has been desired.
• it is necessary to improve the drop strength of molded coal using a mechanism different from the inter-particle adhesion caused by conventional sticky binders.
• the present invention was made in consideration of the above problems, and its purpose is to provide a technology that improves the drop strength of molded coal without increasing the amount of sticky binder.
• blending fibrous pulp is an effective way to improve the strength of molded charcoal through a mechanism different from that of adhesive binders.
• the fibers form an entangled network in the molded charcoal, and the coal particles in the molded charcoal are mechanically restrained, improving the drop strength of the molded charcoal.
• the inventors found that the disintegration and dispersion of the cellulose fibers blended in the molded charcoal production is an important factor in the development of strength, and revealed that the ease with which cellulose fibers disintegrate can be controlled by the fibril circumference, which is an indicator of the degree of fuzz on the surface of cellulose fibers, thereby completing the present invention.
• the gist and configuration of the present invention are as follows.
• a method for producing molded coal for coke production comprising mixing a raw material for molded coal with cellulose fibers having an average fiber length of 0.5 mm or more and 3.0 mm or less and an average fibril circumference of 10% or less, and molding the mixture under pressure to obtain molded coal.
• a strength improving material for molded charcoal characterized by being a cellulose fiber having an average fiber length of 0.5 mm or more and 3.0 mm or less, and an average fibril circumference of 10% or less.
• the present invention provides a technology that improves the drop strength of molded coal without increasing the amount of adhesive binder. Furthermore, by improving the drop strength of molded coal, collapse of the molded coal during transportation can be suppressed, and the productivity of molded coal can be improved.
• the method for producing molded coal according to the present invention is a method for producing molded coal for coke production, characterized in that the raw material for molded coal is mixed with cellulose fibers having an average fiber length of 0.5 mm to 3.0 mm and an average fibril circumference of 10% or less, and the resulting mixed cellulose fiber raw material is pressurized and molded to obtain molded coal.
• the raw material for the molded coal a material that is solid at room temperature, such as coal used in a general molded coal manufacturing method, can be used.
• non-slightly caking coal, coal carbonization products, biomass, charcoal obtained by heating biomass, and other raw materials mainly composed of carbon may be used as long as the quality of the coke obtained by charging the powdered blended coal and the molded coal into a coke oven and carbonizing it is not an issue.
• the raw material for the molded coal is preferably used after adjusting the particle size by crushing it using a hammer crusher or the like so that the ratio of particles with a particle size of -3 mm or less is 70 to 100 mass % (crushing so that the proportion of particles with a particle size of 3 mm or less is 70 to 100 mass %), as is conventionally done.
• cellulose fiber refers to a fibrous material obtained from a cellulose raw material of natural origin.
• the cellulose raw material is preferably pulp, more preferably wood-derived pulp.
• wood-derived pulp include pulp derived from broadleaf trees and pulp derived from softwood trees.
• Chemical pulping methods include, for example, sulfite cooking, kraft cooking, soda-quinone cooking, and organosolv cooking, with kraft cooking being preferred from an environmental and economical perspective.
• the "kraft cooking” method uses alkaline chemicals such as sodium hydroxide, potassium hydroxide, and sodium carbonate in combination with chemicals containing sulfur such as sodium sulfide and sodium sulfite, and quinone-based cooking aids, polysulfides, and other additives can be used.
• the pulp obtained by cooking can be subjected to oxygen delignification.
• the well-known medium or high consistency method can be used as the oxygen delignification method used in the present invention.
• the medium consistency method it is preferable to set the pulp concentration to 8 to 15 mass%, and when using the high consistency method, the pulp concentration to 20 to 35 mass%.
• the alkali in the oxygen delignification process sodium hydroxide or potassium hydroxide can be used, and as the oxygen gas, oxygen from the cryogenic separation method, oxygen separated by the Pressure Swing Adsorption (PSA) method, oxygen separated by the Vacuum Swing Adsorption (VSA) method, etc. can be used.
• PSA Pressure Swing Adsorption
• VSA Vacuum Swing Adsorption
• the reaction conditions for the oxygen delignification treatment are not particularly limited, but may be, for example, an oxygen pressure of 3 to 9 kg/ cm2 .
• the alkali addition rate may be 0.5 to 4 mass%, the temperature may be 80 to 140°C, and the treatment time may be 20 to 180 minutes. Other conditions may be those known in the art.
• the oxygen delignification treatment may be carried out multiple times.
• the pulp that has been subjected to the oxygen delignification treatment may then be sent to a washing process, for example, and after washing, may be subjected to a bleaching treatment as described below.
• Bleaching methods include, for example, a method in which pulp that has been delignified by any conventional method is subjected to chlorine treatment (C), chlorine dioxide bleaching (D), alkaline extraction (E), hypochlorite bleaching (H), hydrogen peroxide bleaching (P), alkaline hydrogen peroxide treatment stage (Ep), alkaline hydrogen peroxide/oxygen treatment stage (Eop), ozone treatment (Z), chelate treatment (Q), or a combination of two or more of these treatments.
• C chlorine treatment
• D chlorine dioxide bleaching
• E alkaline extraction
• H hypochlorite bleaching
• P hydrogen peroxide bleaching
• Ep alkaline hydrogen peroxide treatment stage
• Eop alkaline hydrogen peroxide/oxygen treatment stage
• Z ozone treatment
• Q chelate treatment
• Examples of combinations (sequences) of two or more treatments include D-E/P-D, C/D-E-H-D, Z-E-D-P, Z/D-Ep-D, Z/D-Ep-D-P, D-Ep-D, D-Ep-D-P, D-Ep-P-D, Z-Eop-D-D, Z/D-Eop-D, and Z/D-Eop-D-E-D (the "/" in the sequence means that the treatments before and after the "/" are performed consecutively without washing).
• the bleaching treatment is not limited to the above examples, and may be a commonly used method. Pulp that has been bleached is usually in a fluid state (fluid pulp).
• the moisture content of the above-mentioned pulp is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, when, for example, a pulp sheet is subjected to a crushing process. Furthermore, in order to prevent the raw material fibers from being shortened before and after the crushing of the cellulose fibers of the present invention, the moisture content is more preferably 30% by mass or more, and particularly preferably 40% by mass or more.
• the moisture content of the pulp is preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 70% by mass or less, and particularly preferably 65% by mass or less.
• the moisture content of the pulp is not particularly limited and can be selected as appropriate.
• the average fiber length of the cellulose fibers used in the method for producing molded charcoal according to the present invention is 0.5 mm or more and 3.0 mm or less.
• the strength of the molded charcoal is expressed by forming a network in which the cellulose fibers are entangled with each other in the molded charcoal and mechanically binding the coal particles in the molded charcoal. Therefore, the cellulose fibers used must not be pulp finely crushed into powder, but must be fibrous cellulose fibers, and must have an average fiber length of 0.5 mm or more. If the average fiber length is less than 0.5 mm, the cellulose fibers cannot form a network in which they are entangled with each other in the molded charcoal, and the effect of improving the drop strength cannot be obtained.
• the upper limit of the average fiber length of the cellulose fibers used is not particularly limited from the viewpoint of improving the strength of the molded charcoal.
• the average fiber length of cellulose fibers produced from raw materials derived from coniferous trees, which are generally known to have a large fiber length is about 3.0 mm or less
• the method for producing molded charcoal according to the present invention uses cellulose fibers with an average fiber length of 3.0 mm or less.
• an image analysis type fiber analyzer such as a fractionator manufactured by Valmet or an L&W Fiber Tester Plus manufactured by ABB Corporation.
• the average fiber length of cellulose fibers can be controlled during the pulp production process.
• short fiber length cellulose fibers are obtained when wood chips derived from broadleaf trees are used as the raw material
• long fiber length cellulose fibers are obtained when wood chips derived from coniferous trees are used as the raw material.
• the fiber length of cellulose fibers decreases as a result of processes such as crushing, beating, and grinding during the pulp production process. In order to obtain the cellulose fibers of the present invention, it is particularly preferable to carry out a crushing process.
• the average fibril perimeter of the cellulose fibers used in the method for producing molded charcoal of the present invention is 10% or less.
• the "mean fibril perimeter" is an index of the degree of fluffiness of the surface of the cellulose fibers, and the larger the average fibril perimeter, the more fluffy the cellulose fibers are.
• the larger the average fibril perimeter of the cellulose fibers (in other words, the more fluffy the fibers are), the stronger the bonds between the cellulose fibers become, and the cellulose fibers may become lumpy and not disintegrate in the raw coal during the mixing process in the production of molded charcoal, which may cause defects in the molded charcoal.
• the cellulose fibers In order for the cellulose fibers to form a network in which they are entangled with each other in the molded charcoal and to develop strength, the cellulose fibers must be widely dispersed in the molded charcoal. In this regard, cellulose fibers with a large average fibril perimeter cannot achieve the effect of improving the drop strength of the molded charcoal, which is the object of the present invention. Therefore, the average fibril perimeter of the cellulose fibers used in the present invention is 10% or less, more preferably 8% or less, and even more preferably 5% or less.
• an image analysis type fiber analyzer product name: L&W Fiber Tester Plus manufactured by ABB Corporation
• the average fibril circumference of cellulose fibers increases as beating progresses during pulp production. Therefore, in order to control the average fibril circumference to 10% or less, it is effective to reduce the degree of beating during pulp production, or to directly crush the pulp sheet without performing a beating process.
• mixing cellulose fibers at a mixing ratio of 3.0% by mass or less is a value calculated based on the dry mass of all raw materials.
• mixing cellulose fibers at a mixing ratio of 3.0% by mass or less means mixing the cellulose fibers so that the dry weight of the cellulose fibers is 3.0% by mass or less, when the total dry mass of the raw materials (coal, coal distillate, pitch, other carbonaceous materials, etc., excluding cellulose fibers) that are solid at room temperature used to produce molded charcoal is taken as 100% by mass.
• the blending rate of cellulose fibers is 3.0 mass% or less.
• the blending rate of cellulose fibers is more preferably 0.1 mass% or more and 3.0 mass% or less, and even more preferably 0.1 mass% or more and 2.0 mass% or less.
• a common molding method for molded coal is to add a binder to the raw material for molded coal, which is a mixture of multiple coals and/or carbon materials, knead it in a kneader, and then compact and mold it in a double-roll molding machine.
• Binders other than cellulose fibers In addition to the above-mentioned cellulose fibers, conventionally used binders can be blended and mixed with the coal. Examples of such binders include coal-based binders (coal tar pitch, solvent refined coal, tar, tar slag, etc.), petroleum-based binders (asphalt, asphalt pitch, propane deasphalted asphalt, etc.), and organic binders (starch, molasses, synthetic polymer compounds, resins, etc.).
• coal-based binders coal tar pitch, solvent refined coal, tar, tar slag, etc.
• petroleum-based binders asphalt, asphalt pitch, propane deasphalted asphalt, etc.
• organic binders starch, molasses, synthetic polymer compounds, resins, etc.
• the method for producing molded charcoal according to the present invention can improve drop strength by blending cellulose fibers with controlled average fiber length and average fibril circumference with the raw materials used in typical molded charcoal production methods.
• Molded charcoal can be produced by blending cellulose fibers with the molded charcoal raw materials and molding them under pressure in order to increase the dispersion of cellulose fibers in the molded charcoal raw materials.
• Methods for mixing the raw material for molded charcoal with cellulose fiber include mechanical mixing using a mixer and kneading while heating by introducing steam, and these can be combined as necessary.
• the above-mentioned mixing method is not particularly limited, but when using coal-based, petroleum-based, or organic binders in addition to cellulose fiber, it is preferable to include a heating and kneading step for the purpose of reducing the viscosity of the binders.
• the drop strength of the molded coal is improved and the collapse of the molded coal due to the impact of dropping during transportation is suppressed.
• the drop strength of molded coal is broadly divided into warm drop strength and cold drop strength.
• the warm drop strength is the drop strength of molded coal in a warm state immediately after molded coal raw materials heated by heating and kneading are pressurized and molded to produce molded coal.
• An example of such a situation is when molded coal immediately after molding falls from the molding machine onto a conveyor directly below.
• Coal-based, petroleum-based, and organic binders that have traditionally been used to produce molded coal often develop strength when they cool and harden, and in a warm state, the viscosity decreases and strength is often difficult to develop. Therefore, the mechanical restraint provided by the pulp is expected to improve warm strength, which was difficult to develop with conventional binders.
• the drop strength evaluated when the temperature of the molded coal is 60°C or higher is defined as the warm drop strength.
• the cold drop strength is the drop strength after cooling after molding. Examples of such situations include when molded coal is transferred on a conveyor when being transported, or when it falls inside a hopper when being put into the hopper. Coal-based, petroleum-based, and organic binders that have traditionally been used to manufacture molded coal often solidify and develop strength after cooling. However, when the deformation speed is very high, such as in the case of a drop impact, the solidified binder cannot keep up with the deformation, and cracks may occur in the molded coal. Therefore, it is expected that the cold drop strength will be improved by the pulp binding the coal particles together in the molded coal. In this specification, the cold drop strength is defined as the drop strength evaluated when the temperature of the molded coal is room temperature (e.g., 25°C).
• the strength improving agent for molded coal according to the present invention has an average fiber length of 0.5 mm or more and 3.0 mm or less, and an average fibril circumference of 10% or less. It is characterized by being made of cellulose fibers.
• the cellulose fibers may be the cellulose fibers used in the manufacturing method of molded charcoal according to the present invention described above.
• the requirements for the cellulose fibers may be the same as those for the cellulose fibers used in the manufacturing method of molded charcoal described above.
• molded charcoal with excellent drop strength can be produced. Furthermore, by improving the drop strength of molded charcoal, collapse of the molded charcoal during transportation can be suppressed, and the productivity of molded charcoal can be improved.
• cellulose fibers to be used in the molded charcoal manufacturing method were produced as follows.
• the beaten aqueous dispersion was then adjusted with a centrifugal dehydrator so that the solid content was 30% by mass, to obtain a wet sheet-like material.
• the obtained wet sheet-like material was crushed by treating with a single disc refiner (product name: BR-300CB Lab Refiner (manufactured by Kumagai Riki Kogyo Co., Ltd.), clearance 3.95 mm), to obtain cellulose fiber A having an average fiber length of 0.92 mm and an average fibril circumference of 3.7%.
• Cellulose fiber B having an average fiber length of 1.89 mm and an average fibril circumference of 10.0% was obtained in the same manner as in Production Example 1, except that an unbleached pulp sheet derived from coniferous wood (whiteness 22.8%, solids content 45% by mass/moisture content 55% by mass) was dispersed in water to form a 3% by mass aqueous dispersion.
• a soft material grinder product name: SR-360, manufactured by Horai Co., Ltd., outlet screen diameter: ⁇ 50 mm
• a single disc refiner yield 0.5 mm
• ⁇ Production Example 9> The aqueous dispersion was beaten until the Canadian standard freeness (csf) was 400 ml and the solid content was adjusted to 23% by mass. In the same manner as in Production Example 7, except that, cellulose fiber I having an average fiber length of 0.99 mm and an average fibril circumference of 34.1% was obtained.
• Table 1 shows the average fiber length, average fibril circumference, and blending ratio of the cellulose fibers used in this example.
• Reference example No. 1 is a standard level where no cellulose fibers are blended.
• Invention examples No. 2 to 12 are examples where cellulose fibers suitable for the manufacturing method of molded charcoal of the present invention are blended.
• Comparative examples No. 13 to 15 are examples where the average fiber length or average fibril circumference of the blended cellulose fibers falls outside the range of the present invention. The average fiber length and average fibril circumference of the cellulose fibers used were determined by the method described above.
• the various cellulose fibers listed in Table 1 were used to produce molded charcoal by the following manufacturing method and evaluated.
• the coal used as the raw material for molded charcoal was pulverized to a particle size of 3 mm or less.
• the pulverized coal was mixed with cellulose fiber in the blending ratio (external ratio) listed in Table 1, and 5% by mass of tar slag (external ratio) and 3% by mass of coal tar pitch (internal ratio, as it is solid at room temperature) were further mixed as binders to produce the raw material for molded charcoal.
• the raw material for molded charcoal was mixed in a mixer at room temperature for 90 seconds, and then heated and kneaded for 3 minutes while blowing steam into it in a kneader.
• the mixed raw material was molded in a double-roll molding machine to produce Masek-type molded charcoal with a volume of approximately 30 cc.
• the warm and cold drop strength of the produced molded charcoal was measured, and the strength ratio to a reference example (No. 1) containing no cellulose fiber was taken as the cold drop strength index and warm drop strength index, respectively, and are shown in Table 1.
• Ten molded charcoal pieces were taken and dropped three times from a height of 2 m onto a concrete floor. The percentage of chunks measuring 15 mm or more was taken as the drop strength, and the average value of two similar tests was used as the drop strength for that level.
• the warm drop test was conducted when the molded charcoal was at 60°C or higher immediately after molding, and the cold drop test was conducted after the molded charcoal had been cooled and then at room temperature.
• the present invention provides a technology that improves the drop strength of molded coal without increasing the amount of adhesive binder.

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Citations (6)

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  • 2024-05-29 WO PCT/JP2024/019791 patent/WO2025018037A1/ja active Pending
  • 2024-05-29 JP JP2024566190A patent/JPWO2025018037A1/ja active Pending

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