Manufacturing method of powdered carbide

Abstract

To provide a carbonization processing method with a simple constitution not needing a dry treatment using hot wind and capable of conducting carbonization of a blend containing a sludge.SOLUTION: The method includes: a blending step of blending a biomass such as rice hulls and a dewatered sludge by using a blender 14 to obtain a blend with an apparent water content of 30-70%; and a carbonization step of conducting dry distillation treatment of the blend by using a carbonization furnace 40 under an oxygen-free or a low-oxygen condition at 700-900°C to obtain a carbonized product.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention involves subjecting a mixture of biomass such as rice husks and dewatered sludge to dry distillation to obtain a carbonized product. Manufacturing method of carbide and used in this Carbide manufacturing equipment Regarding. [Background technology]

[0002] Wastewater containing organic matter discharged from households and other facilities is generally treated in sewage treatment facilities. This wastewater treatment process generates organic sludge, and as the amount of wastewater treatment increases, the amount of organic sludge generated also increases year by year, making its treatment and disposal a major problem.

[0003] When disposing of organic sludge, it contains approximately 99.9% water and cannot be disposed of as is. Therefore, various treatments are currently being carried out to reduce the volume, such as concentration and dehydration, or further incineration or melting. Carbonization of organic sludge by dry distillation has been proposed as one method for reducing its volume. Since sludge contains approximately 45% carbon by mass in its matrix, this carbonization process does not consume the carbon in the sludge as in incineration or melting processes, but rather involves thermal decomposition (carbonization) of the sludge in an oxygen-free or low-oxygen environment, leaving the carbon behind and generating a carbonized material (carbonized product) with a new composition.

[0004] When carbonizing sludge by dry distillation, dehydrated sludge that has been dehydrated to a moisture content of about 80% using a dehydrator is used, but if this sludge is dry distilled as is, problems with sludge adhesion may occur, so the sludge is first dried to reduce the moisture content to, for example, about 40%, and then the dried sludge is dry distilled. Carbonization treatment equipment used for such treatment is disclosed, for example, in Patent Document 1 and Patent Document 2 below.

[0005] Figure 8 shows an example of a conventional carbonization treatment facility. In the figure, reference numeral 200 denotes a receiving hopper, into which dewatered sludge that has been dewatered to a moisture content of about 80% is first received. The dewatered sludge received here is sent to a dryer 204 by a sludge transfer pump (quantitative supply device) 202, where it is dried until it reaches a predetermined moisture content, for example, a moisture content of about 40%.

[0006] The dryer 204 is equipped with a rotary drum as a drying container, and sludge is supplied into the interior from one axial end of the rotary drum and moved axially along the interior while the rotary drum is rotated. During this movement, the sludge is dried using hot air, and the dried sludge is discharged from the other axial end. The dried sludge is then sent to the carbonization furnace 208 via the transfer conveyor 206 and carbonized. Finally, carbonized material is discharged from the carbonization furnace 208 as a carbonization residue. In FIG. 8, reference numeral 210 denotes a hot air generating furnace for generating hot air to be supplied to the dryer 204, in which supplied fuel is combusted under the supply of combustion air to generate hot air.

[0007] Such conventional carbonization treatment equipment requires a dryer 204 for drying the sludge and a hot air generating furnace 210 for generating the hot air used for drying, which increases the number of components of the carbonization treatment equipment. In addition, the consumption of fuel for generating the hot air increases the treatment cost.

[0008] Incidentally, Patent Document 3 listed below discloses an invention relating to a "method for carbonizing organic water-containing waste," which discloses that sewage sludge and rice husks are mixed and fed into a rotary kiln to produce a carbonized material. However, the carbonization method described in Patent Document 3 differs from the present invention in that it includes a step of drying the sewage sludge using a dryer and in that it performs dry distillation using a mixture with a lower moisture content than the present invention. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 11-33599 [Patent Document 2] Japanese Patent Application Publication No. 11-37644 [Patent Document 3] Japanese Patent Application Laid-Open No. 2011-68824 Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention has been made in light of the above circumstances, and provides a method for carbonizing a mixture containing sludge using a simple configuration that does not require drying treatment using hot air. Manufacturing method of carbide and Carbide manufacturing equipment This was done with the aim of providing [Means for solving the problem]

[0011] Therefore, claim 1 is Manufacturing method of carbide The method includes a mixing step of mixing biomass and dewatered sludge to obtain a mixture with an apparent moisture content of 30 to 70%, and a step of subjecting the mixture to an oxygen-free or low-oxygen condition. The mixture is placed inside the retort of an externally heated rotary kiln carbonization furnace. and a carbonization process in which carbonization is performed at 700 to 900°C to obtain a carbonized product. 、 In the carbonization step, combustion of combustible gas generated from the mixture is utilized to heat the inside of the retort. Characterized by A method for producing a carbide (excluding a method for producing a carbide by carrying out a reforming reaction of the combustible gas using a catalyst).

[0012] Here, apparent moisture content is the ratio of the wet weight of a mixture of biomass and dewatered sludge to the total weight (the sum of the wet weight of the mixture and the dry weight of the mixture). If the total weight of the mixture is T (g) and the wet weight of the mixture is h (g), then the apparent moisture content p (wt%) can be expressed as p = h / T × 100.

[0013] Claim 2 is characterized in that the biomass is rice husks in claim 1. Here, rice husks are the outer husk portion obtained from grains such as rice and wheat, which are generally known as rice husks and have both grain and husk. Usually, they may be rice husks produced during the threshing process of rice, wheat, etc.

[0014] A third aspect of the present invention is characterized in that, in the second aspect, the rice husks are pulverized so that the bulk density becomes 2 to 10 times. Here, bulk density refers to loose bulk density. Bulk density is measured using a container with an inner diameter of 2.3 cm (volume of 100 cm). 3 ) container, rice husks are fed into it from the top, and when the container is full, the pile of rice husks is scraped off with a spatula and the weight of the total amount of rice husks in the container is measured, and the weight can be calculated using the following formula. Bulk density (g / cm 3 ) = weight of rice husk (g) / volume of container (cm 3 ) According to the above measurement, the bulk density of intact rice husks is approximately 0.1 g / cm 3 In the present invention, the bulk density after pulverization is 0.2 to 1.0 g / cm 3 It is desirable to use rice husks that have become crusty.

[0015] A fourth aspect of the present invention is characterized in that in any one of the first to third aspects, in the mixing step, the biomass such as rice husks and the dewatered sludge are mixed using a two-shaft paddle type or two-shaft rod type mixer.

[0016] A fifth aspect of the present invention is characterized in that in any one of the first to third aspects, in the mixing step, the biomass such as rice husks and the dewatered sludge are mixed using a single screw pump.

[0017] Claim 6 is Carbide manufacturing equipment The present invention relates to a mixer for mixing biomass and dewatered sludge to obtain a mixture, and a mixer for mixing the mixture. At 700-900℃ a carbonization furnace for carbonizing the waste by dry distillation; the carbonization furnace is an externally heated rotary kiln-type carbonization furnace including: a furnace body; a cylindrical retort disposed inside the furnace body; an external heating chamber disposed inside the furnace body and on the outer periphery of the retort; an outlet pipe provided in the retort for allowing combustible gas generated from the mixture to escape from the inside of the retort to the external heating chamber; and an auxiliary burner disposed inside the furnace body for heating the inside of the external heating chamber; The method is characterized in that it does not include a dryer for drying the dewatered sludge. Charcoal manufacturing equipment (excluding charcoal manufacturing equipment equipped with a catalytic reformer that performs a reforming reaction on the combustible gas).

[0018] As described above, the present invention produces carbonized material by using a mixture of biomass such as rice husks and sludge (dehydrated sludge) instead of pure sludge. Although rice husks after threshing are used as livestock bedding, they are generally difficult to dispose of. However, according to the present invention, they can be used effectively without being discarded. In the present invention, the apparent moisture content of the mixture is adjusted by mixing biomass such as rice husks with dewatered sludge, which eliminates the need for the dryers and hot air generators that have been used to adjust the moisture content of sludge, thereby simplifying the components of the carbonization treatment facility.In addition, since hot air for moisture adjustment is no longer necessary, the treatment cost (amount of fuel used) can be reduced.

[0019] The properties required for a carbide vary depending on its intended use. When a powdered carbide is required, the apparent moisture content of the mixture is preferably 30 to 40%, while when a granular carbide that is less likely to scatter is required, the apparent moisture content of the mixture is preferably 60 to 70%. As such, the appropriate apparent moisture content varies depending on the properties required for the carbide, and therefore, in the present invention, the apparent moisture content of the mixture can be appropriately determined within the range of 30 to 70%.

[0020] In the present invention, in addition to whole rice husks, crushed rice husks (rice husk powder) can be used. The use of crushed rice husks allows for more uniform mixing, thereby improving the quality of the resulting charcoal. Furthermore, a mixture of intact rice husks with low bulk density and dewatered sludge has a low density and is prone to scattering into the exhaust gas path inside the carbonization furnace, which may result in a poor carbonized product yield. In contrast, a mixture of finely crushed rice husks and dewatered sludge can be made denser, is less likely to scatter inside the carbonization furnace, and can increase the carbonized product yield. To achieve this effect, it is desirable to use rice husks crushed to a bulk density 2 to 10 times higher.

[0021] In the mixing step of the present invention, the biomass such as rice husks and the dewatered sludge can be mixed using a twin-shaft paddle type or twin-shaft rod type mixer. A twin-shaft paddle or twin-shaft rod mixer is suitable for obtaining a mixture using rice husks with a low bulk density, such as intact rice husks. Furthermore, a mixture produced using a twin-shaft paddle or twin-shaft rod mixer is discharged in a finer, more dispersed state (loose state) than a mixture produced using a single-shaft screw pump (described later) if the apparent moisture content is the same, and is therefore suitable for obtaining finer-grained carbonized material.

[0022] In the mixing step of the present invention, it is also possible to mix the biomass such as rice husks with the dewatered sludge using a single screw pump. When a single-screw pump is used, biomass such as rice husks and dewatered sludge are mixed in a compacted state, making it suitable for forming a dense mixture with few voids. Furthermore, the mixture produced using a single-screw pump is discharged in larger chunks than when the aforementioned twin-screw paddle or twin-screw rod mixers are used, making it suitable for obtaining carbonized material with large particle sizes. Furthermore, when a single-screw pump is used, by directly connecting the single-screw pump and the carbonization furnace with piping, it is possible to omit a conveying device such as a conveyor, thereby simplifying the configuration of the carbonization treatment equipment. [Effects of the Invention]

[0023] According to the present invention as described above, it is possible to provide a carbonization method and carbonization equipment that can carbonize a mixture containing sludge with a simple configuration that does not require drying treatment using hot air. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a diagram showing the configuration of a carbonization treatment facility using a carbonization treatment method according to one embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing a main part of the mixer in FIG. [Figure 3] FIG. 2 is a diagram showing the internal configuration of the carbonization furnace in FIG. [Figure 4] FIG. 2 is a diagram showing the configuration of a carbonization furnace input device in FIG. [Figure 5]FIG. 10 is a diagram showing the configuration of a carbonization treatment facility using a carbonization treatment method according to another embodiment of the present invention. [Figure 6] FIG. 6 is a diagram showing the main part of the mixer in FIG. 5. [Figure 7] FIG. 10 is a diagram showing the configuration of a carbonization treatment facility using a carbonization treatment method according to still another embodiment of the present invention. [Figure 8] FIG. 1 is a diagram showing the overall configuration of a conventional carbonization treatment facility. DETAILED DESCRIPTION OF THE INVENTION

[0025] Next, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows the configuration of a carbonization treatment facility 1 that uses a carbonization treatment method according to one embodiment of the present invention. The carbonization treatment facility 1 includes a first receiving hopper 10, a second receiving hopper 16, a mixer 14, and a carbonization furnace 40, and produces charcoal using organic sludge generated during wastewater treatment. Note that, although the following embodiment uses rice husks as an example, the present invention can also be applied to biomass other than rice husks.

[0026] The first receiving hopper 10 is a dewatered sludge storage tank that receives dewatered sludge that has been dewatered to a moisture content of about 70 to 85% (usually about 80%). The dewatered sludge received in the first receiving hopper 10 is then sent to a mixer 14 by a constant volume feeder 12.

[0027] On the other hand, the second receiving hopper 16 is a rice husk storage tank, and rice husks are received in this second receiving hopper 16. The moisture content of rice husks is about 10%. A rotary valve 17 is connected to the downward discharge outlet 16a of the second receiving hopper 16, and the rice husks received in the second receiving hopper 16 are sent to the mixer 14 via the rotary valve 17. In this example, dewatered sludge and rice husks are respectively supplied to the mixer 14 in a fixed amount so that a mixture with an apparent moisture content of 40% is obtained in the mixer 14. More specifically, they are supplied to the storage tank 20 of the mixer 14.

[0028] The mixer 14 is a twin-shaft paddle mixer, and the mixing step of the present invention is carried out using this mixer 14. The mixer 14 is equipped with a paddle mixer section 21 and a storage tank 20 attached to an inlet 21a of the paddle mixer section 21. The paddle mixer section 21 has a pair of rotating shafts 22, 24 (see FIG. 2) provided inside a casing, and approximately flat plate-shaped mixing blades 26, 28 fixedly attached radially to each shaft. In the paddle mixer section 21, the rotary shafts 22, 24 rotate in opposite directions, and the dewatered sludge and rice husks supplied to the paddle mixer section 21 from the storage tank 20 are mixed by being kneaded at the overlapping portions of the mixing blades 26, 28.

[0029] In this mixer 14, the rotating shafts 22 and 24 rotate at unequal speeds. Therefore, there is a difference in peripheral speed between the mixing blades 26 and 28, and this difference in peripheral speed enables the dewatered sludge and rice husks to be kneaded together with high efficiency.

[0030] The mixing blades 26, 28 are attached at an angle to the rotating shafts 22, 24, respectively, and the dewatered sludge and rice husks supplied to the paddle mixer section 21 are mixed and sent axially by the feeding action of the mixing blades 26, 28. A mixture of the dewatered sludge and rice husks with a predetermined apparent moisture content (apparent moisture content of 40% in this example) is then discharged from the discharge outlet 21b provided at the axial end. The discharged mixture is transported to the carbonization furnace 40 by the transport conveyor 38.

[0031] In the mixer 14 of this embodiment, the mixing blades 26, 28 may be replaced with rods in some cases to form a twin-rod mixer.

[0032] The carbonization furnace 40 is an externally heated rotary kiln type carbonization furnace that dehydrates and pyrolyzes the material to be treated in an oxygen-free or low-oxygen atmosphere with an oxygen concentration of 10% or less, and the carbonization process in the present invention is carried out using this carbonization furnace 40. As shown in Figure 3, the carbonization furnace 40 has a cylindrical retort 44 as a dry distillation container inside the furnace body 42, and a mixture as the material to be treated, with a moisture content adjusted to 40%, is placed inside the left end of this retort 44 in the figure. The charged mixture is first heated by heating the atmosphere inside the external heating chamber 48 using the auxiliary burner 46 installed inside the furnace body 42. Then, the combustible gas contained in the mixture escapes into the atmosphere inside the external heating chamber 48 through the blow-out pipe 45 installed in the retort 44, and this combustible gas is ignited, and thereafter the mixture inside the retort 44 is heated by the combustion of this combustible gas. At this stage, the combustion of the auxiliary burner 46 is stopped.

[0033] An air inlet 43 is formed in the furnace body 42 surrounding the external heating chamber 48 to introduce combustion air into the external heating chamber 48. In this example, a control unit (not shown) adjusts the amount of combustion air introduced into the external heating chamber 48 through the air inlet 43, thereby controlling the temperature of the external heating chamber 48 to match a preset target temperature.

[0034] The mixture inside retort 44 moves from the left end in the figure to the right as retort 44 rotates (retort 44 has a slight gradient), and the water is efficiently evaporated on the upstream side of retort 44. After moving to the downstream side of retort 44, it is carbonized at 700 to 900°C, which is close to the atmosphere in external heating chamber 48. Finally, the carbonized material (carbonized product) as the carbonization residue is discharged from outlet 52 on the right end of retort 44 in the figure, i.e., from carbonization furnace 40.

[0035] An exhaust gas treatment chamber 50 separated from the external heating chamber 48 is provided inside the furnace body 42, and exhaust gas from the external heating chamber 48 is led here. An exhaust gas treatment chamber burner 47 is provided in the exhaust gas treatment chamber 50, and unburned gas in the exhaust gas led into the exhaust gas treatment chamber 50 is subjected to secondary combustion in this exhaust gas treatment chamber burner 47. The exhaust gas in the exhaust gas treatment chamber 50 is then discharged from the exhaust port 51. An exhaust gas passage extends from the exhaust gas treatment chamber 50 through the exhaust port 51, and the exhaust gas from the carbonization furnace 40 is passed through the exhaust gas passage by a carbonization furnace exhaust gas fan, passes through a carbonization furnace exhaust gas heat exchanger, and is discharged to the outside from a chimney, as shown in FIG.

[0036] 4, a carbonization furnace charger 54 is provided at the front end of the carbonization furnace 40 of this example. The carbonization furnace charger 54 includes a screw conveyor 60, and a storage tank 56 is attached to an inlet 60a of the screw conveyor 60. A rotating shaft 57 is rotatably supported inside the storage tank 56, and a plurality of scraping pieces 58 that rotate integrally with the rotating shaft 57 are provided at different axial positions of the rotating shaft 57. The rotating shaft 57 and scraping pieces 58 are connected to the drive mechanism of the screw conveyor 60 so as to rotate in conjunction with the screw conveyor 60.

[0037] The screw conveyor 60 includes a screw shaft 61, screw blades 62 spirally protruding from the screw shaft 61, and a drive motor 63 that drives the screw shaft 61 to rotate, and the discharge end of the screw conveyor 60 is inserted into the retort 44 of the carbonization furnace 40.

[0038] In this example, the mixture introduced into storage tank 56 falls toward screw conveyor 60 below due to the rotational movement of scraping pieces 58 inside storage tank 56. The dropped mixture is received in the grooves between screw blades 62 of screw conveyor 60 and is pushed forward as screw shaft 61 rotates, and is introduced into retort 44.

[0039] According to the carbonization method of this embodiment as described above, the apparent moisture content of the mixture is adjusted by mixing the rice husks with the dewatered sludge, which eliminates the need for the dryer and hot air generating furnace that have conventionally been used to adjust the moisture content of the sludge, thereby simplifying the components of the carbonization treatment facility 1. Furthermore, since hot air is no longer required to dry the mixture before the dry distillation treatment, the treatment cost (amount of fuel used) can be reduced.

[0040] In addition, in this embodiment, a two-shaft paddle mixer 14 is used in the mixing process in which rice husks and dewatered sludge are mixed to obtain a mixture.Therefore, if the apparent moisture content is the same, the resulting mixture is discharged in a finely divided (loose) state compared to when a single-shaft screw pump described below is used, making it suitable for obtaining finer-grained carbonized material.

[0041] In this embodiment, in addition to whole rice husks, crushed rice husks (rice husk powder) can be used. By using crushed rice husks, more uniform mixing with sludge can be achieved, and the quality of the carbonized material produced can be improved. Furthermore, a mixture of intact rice husks with low bulk density and dewatered sludge has a low density and is likely to scatter into the exhaust gas path inside the carbonization furnace 40, which may result in a decrease in the yield of carbonized material. In contrast, a mixture of finely crushed rice husks and dewatered sludge can have a high density, making it less likely to scatter inside the carbonization furnace 40 and increasing the yield of carbonized material. To achieve this effect, it is desirable to use rice husks that have been crushed to a bulk density of 2 to 10 times the original size. Crushing of rice husks can be carried out using a mortar and pestle, a hammer mill, or the like.

[0042] Fig. 5 is a diagram showing another embodiment (second embodiment) of the present invention. This embodiment differs from the first embodiment in that a single-shaft screw pump is used in the mixing process to mix rice husks and dewatered sludge. The other configurations are the same as those of the first embodiment.

[0043] A mixer 64 in a carbonization treatment facility 1B shown in FIG. 5 includes a single-shaft screw pump 68 and a storage tank 66 attached to an inlet 68a of the single-shaft screw pump 68. As shown in Figure 6, the single-axis screw pump 68 includes a stator 70 and a rotor 72 inside a cylindrical casing 69. The stator 70 is twisted at a constant twist angle and has an oval cross-sectional through-hole extending in the axial direction. The rotor 72 is rod-shaped with a circular cross-section and is disposed along the through-hole of the stator 70. A spiral cavity 74 is formed between the stator 70 and the rotor 72, continuing in the axial direction.

[0044] The rotor 72 is connected to a drive motor 76 via a joint member (not shown). When the drive motor 76 rotates, the rotor 72 rotates within the through-hole having an oval cross section, causing the contents contained within the cavity 74 to gradually move in the axial direction.

[0045] As shown in FIG. 5, the discharge port 68b of the single screw pump 68 is connected to the carbonization furnace 40 (more specifically, the storage tank 56 of the carbonization furnace charger 54) by a pipe 77.

[0046] In this example, the rice husks and dewatered sludge that flow into the cavity 74 through the inlet 68a are mixed in a compressed state by the rotating rotor 72, so that a mixture with fewer voids and higher density can be continuously formed compared to the twin-shaft paddle mixer used in the first embodiment above. As described above, according to the carbonization method of this embodiment, a high-density mixture is supplied to the carbonization furnace 40, so that the mixture can be prevented from scattering into the exhaust gas path inside the carbonization furnace 40, which would result in a decrease in the yield of carbonized material. This effect is particularly effective when using rice husks that have been pulverized to have a bulk density of 2 to 10 times the original volume.

[0047] In addition, in this example, the discharge outlet 68b of the single-axis screw pump 68 is directly connected to the carbonization furnace 40 by piping 77, and the mixture can be supplied to the carbonization furnace 40 without using a separate conveying device such as the conveyor 38 in the first embodiment described above, thereby further simplifying the configuration of the carbonization treatment equipment.

[0048] 7 is a diagram showing yet another embodiment (third embodiment) of the present invention. This embodiment differs from the second embodiment in that a second mixer 80 of a twin-shaft paddle type is provided between the mixer 64 using a single-shaft screw pump 68 and the carbonization furnace 40. The configuration of the second mixer 80 is the same as that of the twin-shaft paddle type mixer 14 in the first embodiment.

[0049] In this example, the discharge port 68b of the uniaxial screw pump 68 and the storage tank 20 of the second mixer 80 are connected by a pipe 82, and the mixture mixed by the uniaxial screw pump 68 is transported to the second mixer 80 through the pipe 82. In addition, a transport conveyor 38 is provided between the second mixer 80 and the carbonization furnace 40, and is configured so that the mixture discharged from the second mixer 80 is transported to the carbonization furnace 40.

[0050] According to this example, a more uniformly mixed mixture can be obtained by using two types of mixers 64 and 80. In addition, the mixture in a finely granulated state can be supplied to the carbonization furnace 40 by the second mixer 80 of a twin-shaft paddle type provided in the subsequent stage.

[0051] <Other variations and application examples> In the present invention, it is also possible to mix biomass other than rice husks with dewatered sludge to obtain a mixture with a predetermined moisture content. Here, biomass refers to organic resources derived from living organisms, and specific examples include: (1) inedible parts of agricultural crops such as rice straw, banana stalks, coffee grounds, coconut shells / husks, coconut husks, corn cobs, sugarcane pomace, cassava stems, and other food residues; (2) resource crops such as sugarcane, corn, and cassava; and (3) wood chips and pellets, thinned wood, and waste wood obtained from wood.

[0052] These biomass materials have various properties. Therefore, biomass can be cut or crushed as needed to ensure uniform mixing with the dewatered sludge and to obtain carbonized material of the desired particle size. The length of the biomass used is preferably 30 mm or less, and more preferably 20 mm or less. The moisture content of the biomass used is preferably 30% or less, and more preferably 20% or less.

[0053] Even when using biomass other than rice husks, it can be mixed with dewatered sludge using a biaxial paddle or biaxial rod mixer as exemplified in the above embodiment, and / or a mixer equipped with a single-axis screw pump.

[0054] Although the embodiments of the present invention have been described in detail above, these are merely examples, and the present invention can be embodied in various modified forms without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0055] 1, 1B, 1C carbonization treatment equipment 14,64,80 Mixer 40 Carbonization furnace

Claims

1. a mixing step of mixing biomass and dewatered sludge to obtain a mixture having an apparent moisture content of 30 to 70% (excluding 60 to 70%); a carbonization step of carbonizing the mixture introduced into a retort of an externally heated rotary kiln-type carbonization furnace at 700 to 900°C under oxygen-free or low-oxygen conditions to obtain a powdery carbonized product; A method for producing a powdered charcoal, characterized in that in the carbonization process, combustion of combustible gas generated from the mixture is used to heat the inside of the retort (excluding methods for producing charcoal by carrying out a reforming reaction of the combustible gas using a catalyst).

2. 2. The method for producing a powdery charcoal according to claim 1, wherein the biomass is rice husk.

3. The method for producing powdered carbide according to claim 2, characterized in that the rice husks are pulverized so that the bulk density is increased by 2 to 10 times.

4. The method for producing powdery carbonized material described in any one of claims 1 to 3, characterized in that in the mixing step, the biomass such as rice husks and dewatered sludge are mixed using a biaxial paddle type or a biaxial rod type mixer.

5. The method for producing powdery carbonized material according to any one of claims 1 to 3, characterized in that in the mixing step, the biomass such as rice husks and the dewatered sludge are mixed using a single-axis screw pump.

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