Fluidized bed furnace and fluidized medium recovery method

Abstract

To provide a fluid bed furnace which can efficiently recover valuable metal from a fluid medium stored in a furnace body, and to provide a fluid medium recovery method.SOLUTION: A fluid bed furnace incinerates or gasifies a processed object including valuable metal and includes: a furnace body in which a fluid medium 13 is stored; and an air diffusing mechanism A which sprays fluidizing gas to the fluid medium 13. The furnace body has: a furnace bottom plate 16 for supporting the fluid medium 13; and a discharge port 16a which is provided adjacent to the furnace bottom plate 16 and may discharge the fluid medium 13. The furnace bottom plate 16 has a sedimentation mechanism B which, when the air diffusing mechanism A is stopped and the fluid medium 13 is extracted from the discharge port 16a, causes the remaining fluid medium 13 to accumulate to form a sedimentary layer 13a at a position different from that of the air diffusing mechanism A.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a fluidized bed furnace and a method for recovering a fluid medium in a fluidized bed furnace.

Background Art

[0002] As described in Patent Document 1, as fluidized bed furnaces, there are known a fluidized bed incinerator for incinerating various wastes in a state where a fluid medium such as sand flows, and a fluidized bed gasifier for gasifying the wastes. These fluidized bed furnaces are provided with a circulation mechanism for extracting the fluid medium from the furnace bottom, separating incombustibles from the fluid medium, and then returning it to the furnace body.

[0003] The fluidized bed furnace described in Patent Document 1 is configured to recover the fluid medium by extracting it from a discharge port (referred to as "extraction port" in the document) provided at the furnace bottom. The wastes incinerated or the like by the fluidized bed furnace contain trace amounts of valuable metals such as precious metals like gold and silver or heavy metals like lead and zinc. It is known that the fluid medium remaining on the furnace bottom plate and not extracted from the discharge port among the fluid medium accommodated in the fluidized bed furnace contains valuable metals derived from the wastes at a high concentration. Therefore, in the fluidized bed furnace, after inclining the furnace bottom plate toward the discharge port to discharge the fluid medium from the discharge port by gravity, valuable metals are recovered from the fluid medium remaining on the furnace bottom plate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As described above, in the fluidized bed furnace described in Patent Document 1, it is necessary to leave a certain amount or more of the fluidized medium on the furnace bottom plate in order to recover a large amount of valuable metals from the fluidized medium. Therefore, there was room for improvement in efficiently recovering valuable metals from the fluidized medium remaining on the furnace bottom plate.

[0006] The present invention has been made in view of the above problems, and its objective is to provide a fluidized bed furnace and a fluidized medium recovery method that can efficiently recover valuable metals from a fluidized medium contained in the furnace body. [Means for solving the problem]

[0007] The characteristic configuration of the fluidized bed furnace according to the present invention is a fluidized bed furnace that incinerates or gasifies a material to be processed, which includes valuable metals, A furnace body containing a fluid medium, The system includes a diffusion mechanism for blowing a fluidizing gas to make the fluid medium flow, The furnace body has a furnace bottom plate that supports the fluid medium, and a discharge port provided adjacent to the furnace bottom plate that can discharge the fluid medium. The furnace bottom plate has a deposition mechanism, located at a different position from the aeration mechanism, that, when the aeration mechanism is stopped and the fluidizing medium is extracted from the discharge port, deposits the remaining fluidizing medium to form a deposit layer. Occasionally, The aforementioned accumulation mechanism is provided on the furnace bottom plate and consists of a damming member that prevents the fluid medium from flowing into the discharge port. It's at a single point.

[0008] In this configuration, since the fluidized bed furnace has a deposition mechanism, when the aeration mechanism is stopped and the fluidized medium filled in the furnace body is removed from the discharge port, a large amount of fluidized medium remains on the furnace bottom plate as a deposition layer. Furthermore, because the deposition mechanism is located in a different position from the aeration mechanism, it can efficiently form a deposition layer without hindering the aeration process of the aeration mechanism during operation. As a result, while removing the fluidized medium containing non-combustible materials from the discharge port, a larger amount of fluidized medium can be left on the furnace bottom plate compared to a configuration without a deposition mechanism. Consequently, valuable metals can be efficiently recovered from the fluidized medium remaining on the furnace bottom plate. Furthermore, with this configuration, since a damming member is provided on the furnace bottom plate as a deposition mechanism, the damming member can prevent the fluid medium from flowing into the discharge port due to gravity. As a result, the fluid medium dammed by the damming member acts as resistance to the fluid medium moving along the surface of the furnace bottom plate towards the discharge port, making it possible to deposit a large amount of fluid medium on the furnace bottom plate and form a deposition layer from the fluid medium. .

[0009] The characteristic configuration of the fluidized bed furnace according to the present invention is a fluidized bed furnace that incinerates or gasifies a material to be processed, which includes valuable metals, A furnace body containing a fluid medium, The system includes a diffusion mechanism for blowing a fluidizing gas to make the fluid medium flow, The furnace body has a furnace bottom plate that supports the fluid medium, and a discharge port provided adjacent to the furnace bottom plate that can discharge the fluid medium. The furnace bottom plate has a deposition mechanism, located at a different position from the aeration mechanism, that deposits the remaining fluid medium to form a deposition layer when the aeration mechanism is stopped and the fluid medium is extracted from the discharge port. The aforementioned accumulation mechanism is characterized by having multiple stepped portions on the surface of the furnace bottom plate such that the end of the furnace bottom plate on the discharge port side is the lowest. .

[0010] In this configuration, since the fluidized bed furnace has a deposition mechanism, when the aeration mechanism is stopped and the fluidized medium filled in the furnace body is removed from the discharge port, a large amount of fluidized medium remains on the furnace bottom plate as a deposition layer. Furthermore, because the deposition mechanism is located in a different position from the aeration mechanism, it can efficiently form a deposition layer without hindering the aeration process of the aeration mechanism during operation. As a result, while removing the fluidized medium containing non-combustible materials from the discharge port, a larger amount of fluidized medium can be left on the furnace bottom plate compared to a configuration without a deposition mechanism. Consequently, valuable metals can be efficiently recovered from the fluidized medium remaining on the furnace bottom plate. Furthermore, as in this configuration, if multiple stepped sections are provided on the surface of the furnace bottom plate so that the end of the bottom plate on the outlet side is the lowest, the fluid medium will remain and accumulate in the stepped sections of the furnace bottom plate, forming a large accumulation layer of fluid medium around the multiple stepped sections. As a result, valuable metals can be efficiently recovered from the fluid medium remaining on the furnace bottom plate. .

[0011] Another characteristic feature is that the damming member is provided at the end of the furnace bottom plate on the outlet side.

[0012] According to this configuration, the damming member, which acts as a deposition mechanism, only needs to be installed at the end of the furnace bottom plate on the outlet side, making it possible to retrofit existing fluidized bed furnaces, and thus efficient. As a result, valuable metals can be efficiently recovered from the deposition layer of fluidized medium remaining on the furnace bottom plate.

[0013] Another characteristic feature is that the end of the furnace bottom plate on the discharge side is formed as a horizontal plane.

[0014] As in this configuration, when the end of the furnace bottom plate on the outlet side is formed as a horizontal surface, the fluidized medium remains on the horizontal surface of the furnace bottom plate and accumulates. This allows for the formation of a deposit layer of fluidized medium on the furnace bottom plate. As a result, valuable metals can be efficiently recovered from the fluidized medium remaining on the furnace bottom plate.

[0015] Another characteristic feature is that the aeration mechanism includes a plurality of aeration pipes protruding from the surface of the furnace bottom plate.

[0016] According to this configuration, since the air diffusing mechanism includes a plurality of air diffusing pipes protruding from the surface of the furnace bottom plate, the plurality of air diffusing pipes can be easily and dispersedly arranged on the furnace bottom plate, and the fluid medium supported by the furnace bottom plate by the plurality of air diffusing pipes can be efficiently flowed.

[0017] Another characteristic configuration lies in that the whole or a part of the furnace bottom plate is inclined at an angle smaller than the angle of repose of the fluid medium.

[0018] According to this configuration, since the whole or a part of the furnace bottom plate is inclined at an angle smaller than the angle of repose of the fluid medium, when the fluid medium supported by the furnace bottom plate is allowed to flow into the discharge port by gravity and extracted, not all of the fluid medium filled in the furnace body will be extracted out of the furnace, and a part of the fluid medium can be reliably left on the furnace bottom plate.

[0019] A characteristic of the fluid medium recovery method according to the present invention is a fluid medium recovery method for stopping a fluidized bed furnace that incinerates or gasifies a treatment target containing a valuable metal to recover the fluid medium, where the fluidized bed furnace comprises a furnace body for accommodating the fluid medium, and an air diffusing mechanism for blowing a fluidizing gas for flowing the fluid medium, where the furnace body has a furnace bottom plate for supporting the fluid medium and a discharge port provided adjacent to the furnace bottom plate for discharging the fluid medium, where the furnace bottom plate has a deposition mechanism for depositing the remaining fluid medium to form a deposition layer at a position different from the air diffusing mechanism in a state where the air diffusing mechanism is stopped and the fluid medium is extracted from the discharge port, The aforementioned accumulation mechanism is provided on the furnace bottom plate and consists of a damming member that prevents the fluid medium from flowing into the discharge port. an extraction step of stopping the air diffusing mechanism and allowing the fluid medium supported by the furnace bottom plate to flow into the discharge port and be extracted, and a recovery step of recovering the fluid medium remaining on the furnace bottom plate after the extraction step, where in the extraction step, the fluid medium is deposited on the furnace bottom plate by the deposition mechanism.

[0020] The characteristic of the fluidized medium recovery method according to the present invention is a fluidized medium recovery method that recovers the fluidized medium by stopping a fluidized bed furnace that incinerates or gasifies a material containing valuable metals, The aforementioned fluidized bed furnace is A furnace body containing the aforementioned fluid medium, The system includes a diffusion mechanism for blowing a fluidizing gas to make the fluid medium flow, The furnace body has a furnace bottom plate that supports the fluid medium, and a discharge port provided adjacent to the furnace bottom plate that can discharge the fluid medium. The furnace bottom plate has a deposition mechanism, located at a different position from the aeration mechanism, that deposits the remaining fluid medium to form a deposition layer when the aeration mechanism is stopped and the fluid medium is extracted from the outlet. The aforementioned deposition mechanism is provided with a plurality of stepped portions on the surface of the furnace bottom plate such that the end of the furnace bottom plate on the discharge port side is the lowest. A extraction step in which the aeration mechanism is stopped and the fluid medium supported on the furnace bottom plate is allowed to flow into the discharge port and extracted, The process includes a recovery step of recovering the fluid medium remaining on the furnace bottom plate after the extraction step, In the extraction process, the fluid medium is deposited on the furnace bottom plate by the deposition mechanism. It's at a single point.

[0021] According to this method, after stopping the aeration mechanism, the fluidized medium filled in the furnace body is drawn out of the furnace body by flowing it into the discharge port (extraction process). During this extraction process, the deposition mechanism of the furnace bottom plate allows the fluidized medium to be deposited as a deposition layer on the furnace bottom plate and remain there. Furthermore, the deposition layer on the furnace bottom plate acts as resistance to the fluidized medium moving along the surface of the furnace bottom plate towards the discharge port, making it difficult for the fluidized medium on the furnace bottom plate to flow towards the discharge port. As a result, during the extraction process, while extracting the fluidized medium containing non-combustible material from the discharge port, it is possible to leave more fluidized medium on the furnace bottom plate compared to a case where there is no deposition mechanism on the furnace bottom plate. Consequently, valuable metals can be efficiently recovered from the fluidized medium remaining on the furnace bottom plate. [Brief explanation of the drawing]

[0022] [Figure 1] This diagram schematically shows the configuration of the fluidized bed furnace equipment in the first embodiment. [Figure 2] This is a partial cross-sectional view showing the structure of the furnace bottom plate in a fluidized bed furnace. [Figure 3] This is a partial plan view showing the configuration of the diffuser pipes in a fluidized bed furnace. [Figure 4] This is a plan view of a fluidized bed furnace. [Figure 5] This is a cross-sectional view of a fluidized bed furnace with fluidized medium remaining on the furnace bottom plate. [Figure 6] This is a partial cross-sectional view showing the configuration of the furnace bottom plate in a fluidized bed furnace according to the second embodiment. [Figure 7]This is a partial cross-sectional view showing the configuration of the furnace bottom plate of a modified example 1 of the second embodiment. [Figure 8] This is a partial cross-sectional view showing the configuration of the furnace bottom plate of a modified example 2 of the second embodiment. [Figure 9] This is a plan view showing the configuration of the furnace bottom plate in a fluidized bed furnace according to the third embodiment. [Figure 10] This is a partial cross-sectional view showing the configuration of the furnace bottom plate in a fluidized bed furnace according to the third embodiment. [Figure 11] This is a plan view of a fluidized bed furnace according to another embodiment. [Figure 12] This is a cross-sectional view of a fluidized bed furnace in another embodiment, showing a fluidized medium remaining on the furnace bottom plate. [Modes for carrying out the invention]

[0023] Hereinafter, a fluidized bed furnace and a method for recovering the fluidized medium in a fluidized bed furnace according to embodiments of the present invention will be described in detail based on the drawings. Note that the embodiments described below are illustrative examples for explaining the present invention and do not limit the present invention to these embodiments only. Therefore, the present invention can be implemented in various forms without departing from its essence.

[0024] [First Embodiment] (Configuration of Fluidized Bed Furnace System) The configuration of the fluidized bed furnace equipment 1 will be explained with reference to Figures 1 to 5. As shown in Figure 1, the fluidized bed furnace equipment 1 mainly consists of a fluidized bed gasifier 10 (an example of a fluidized bed furnace, hereinafter abbreviated as "fluidized bed furnace 10"), a swirling flow melting furnace 20, and a duct 30. These components will be explained below.

[0025] The fluidized bed furnace 10 is a facility for thermally decomposing various types of waste, such as municipal solid waste, sewage sludge, automobile shredder residue (ASR), or discarded home appliances, as well as combustible materials such as home appliances containing valuable metals, into combustible gases (carbon monoxide, hydrogen, hydrocarbons, etc.), unburned material (char), and ash. The waste to be processed includes valuable metals, and the fluidized bed furnace 10 incinerates or gasifies the waste. As shown in Figure 1, the fluidized bed furnace 10 is equipped with a furnace body 12 that houses a fluidized medium 13. The furnace body 12 (fluidized bed furnace 10) has a furnace bottom plate 16 that supports the fluidized medium 13, and an outlet 16a provided adjacent to the furnace bottom plate 16 for discharging the fluidized medium 13. In this embodiment, a circular opening is formed in the central part of the furnace bottom plate 16, and the outlet 16a is formed by this opening. A discharge pipe 15 extending downward from the furnace bottom plate 16 is connected to the outlet 16a. Furthermore, the fluidized bed furnace 10 is equipped with a diffuser mechanism A that blows fluidizing gas toward the fluidized medium 13. In this embodiment, the diffuser mechanism A is configured to blow the fluidizing gas from below the furnace bottom plate 16. Although not shown, the diffuser mechanism A may also be configured to blow the fluidizing gas from above the furnace bottom plate 16 and from the side of the furnace body 12.

[0026] The furnace body 12 has a cylindrical shape, for example, extending vertically. The furnace body 12 is provided with a supply port 14, an outlet port 11, and an inlet port 17. The material to be processed is supplied into the furnace body 12 from the supply port 14. The combustible gas generated inside the furnace body 12 is discharged outside the furnace from the outlet port 11. As a diffusion mechanism A, a wind box 18 is provided in the space below the furnace bottom plate 16 inside the furnace body 12, and a fluidizing gas (for example, air) for fluidizing the fluidizing medium 13 is introduced into the wind box 18 from the inlet port 17. As shown in Figure 1, the supply port 14 is provided on the side of the furnace body 12 in a part above the furnace bottom plate 16. The outlet port 11 is provided at the top of the furnace body 12. The inlet port 17 is provided on the side of the furnace body 12 in a part below the furnace bottom plate 16.

[0027] The furnace bottom plate 16 is located at the bottom of the furnace body 12. The discharge port 16a for the fluidizing medium 13 is formed on the inner circumference of the furnace bottom plate 16. Numerous diffuser pipes 19 penetrate the furnace bottom plate 16. As shown in Figure 1, the furnace bottom plate 16 is inclined downward toward the inner circumferential outlet 16a, and its inclination angle is smaller than the angle of repose of the fluid medium 13. Specifically, while the angle of repose of the fluid medium 13 is preferably 30 to 40 degrees, the inclination angle of the furnace bottom plate 16 is 10 to 30 degrees. In Figure 5, the inclination angle (angle θ) of the furnace bottom plate 16 is shown as the angle between the horizontal direction (dotted line Y in Figure 5) and the surface 16c of the furnace bottom plate 16. In this embodiment, the entire furnace bottom plate 16 is inclined at an angle smaller than the angle of repose of the fluid medium 13, but the furnace bottom plate 16 may also be configured such that only a part of it is inclined at an angle smaller than the angle of repose of the fluid medium 13.

[0028] The fluidized medium 13 is, for example, fluidized sand such as silica sand or olivine sand, and is filled on the furnace bottom plate 16. As a result, a fluidized bed (sand layer) of a predetermined thickness is formed on the furnace bottom plate 16, as shown in Figure 1. The fluidized bed furnace 10 processes materials containing valuable metals (for example, gold, silver, copper, lead, or zinc) while the fluidized medium 13 is in a fluid state.

[0029] The discharge pipe 15 is for draining the fluid medium 13 along with non-combustible material to the outside of the furnace body 12. As shown in Figure 1, the discharge pipe 15 has an upper end connected to the discharge port 16a and a lower end located outside the furnace body 12, and extends vertically from the upper end to the lower end, penetrating the bottom wall of the furnace body 12.

[0030] Aeration mechanism A consists of an inlet 17, a wind box 18, and a plurality of diffusers 19. As shown in Figures 2 and 3, each diffuser 19 has a straight pipe section 19a that penetrates the furnace bottom plate 16 in the thickness direction, and a U-shaped pipe section 19b connected to the upper end of the straight pipe section 19a. As shown in Figure 1, in order to make the fluidizing medium 13 fluid, aeration mechanism A circulates the fluidizing gas introduced from the inlet 17 to the wind box 18 through the diffusers 19, blowing the fluidizing gas from below the furnace bottom plate 16 of the furnace body 12 toward the fluidizing medium 13. As shown in Figures 3 and 4, a plurality of diffusers 19 are arranged radially on the furnace bottom plate 16. The fluidizing gas introduced from the inlet 17 to the wind box 18 rises inside the straight pipe section 19a and is then sent toward the fluidizing medium 13 from the opening of the U-shaped pipe section 19b (arrow in Figure 3).

[0031] As shown in Figures 1 to 4, the furnace bottom plate 16 has a deposition mechanism B at a different location from the aeration mechanism A, which deposits the fluid medium 13 to form a deposition layer 13a when the aeration mechanism A is stopped and the fluid medium 13 is extracted from the outlet 16a. The deposition mechanism B is composed of a damming member 16b provided on the furnace bottom plate 16. In this embodiment, the damming member 16b is provided at the opening periphery, which is the end of the furnace bottom plate 16 on the outlet 16a side, and prevents the fluid medium 13 remaining on the furnace bottom plate 16 from flowing into the outlet 16a due to gravity.

[0032] As shown in Figure 1, the swirling flow melting furnace 20 is a furnace that completely combusts the combustible gas and unburned material while forming a swirling flow 100 of the combustible gas generated in the fluidized bed furnace 10, and also melts the ash entrained in the combustible gas. The swirling flow melting furnace 20 has a melting furnace body 23. The melting furnace body 23 is provided with a combustible gas inlet 21 and a slag outlet 22 for discharging molten slag to the outside of the furnace. Molten slag is formed when the ash of the combustible gas that flows into the melting furnace body 23 from the inlet 21 melts.

[0033] The inlet 21 is located on the side of the melting furnace body 23, near the top. The inlet 21 is connected to the outlet 11 of the fluidized bed furnace 10 by a duct 30. The slag outlet 22 is located at the bottom of the melting furnace body 23. The exhaust gas generated by the combustion of combustible gas in the swirling flow melting furnace 20 passes through various equipment (boiler, cooling tower, bag filter, catalytic reaction tower, etc.) located downstream of the swirling flow melting furnace 20, and is then released into the atmosphere through a chimney (not shown).

[0034] The fluidized bed furnace 10 has a circulation path 40. The circulation path 40 returns the fluidized medium 13, which has been extracted to the outside of the furnace body 12, to the furnace body 12 after being separated from non-combustible materials. The circulation path 40 includes an extraction screw 41, a classifier 42, a circulation elevator 43, a storage tank 44, a first transport path 45, a second transport path 46, and a third transport path 47.

[0035] The extraction screw 41 is used to extract the fluid medium 13 together with non-combustible material from the bottom of the furnace body 12 by rotational drive, and is located at the lower end of the discharge pipe 15. The classifier 42 is located at the downstream end of the extraction screw 41 and separates the fluid medium 13 from the non-combustible material by sieving. The non-combustible material separated from the fluid medium 13 is crushed and then slag-formed in the swirling flow melting furnace 20, or transported out of the system.

[0036] The circulating elevator 43 transports the fluid medium 13, from which non-combustible materials have been removed by the classification device 42, to a predetermined height. As shown in Figure 1, an inlet 43A for the fluid medium 13 is provided at the bottom of the circulating elevator 43, and this inlet 43A is connected to the outlet 42A of the classification device 42 (the outlet for the fluid medium 13) by the first transport path 45. An outlet 43B for the fluid medium 13 is also provided at the top of the circulating elevator 43.

[0037] The storage tank 44 stores the fluid medium 13 that has been transported upward by the circulating elevator 43. The second transport path 46 is provided from the exit 43B of the circulating elevator 43 to the inlet 43A, with a storage tank 44 located along the way. This allows the fluid medium 13, which has been transported upward by the circulating elevator 43, to fall into the storage tank 44 via the second transport path 46 and be stored in the storage tank 44.

[0038] The third transport path 47 is connected at one end to a portion of the second transport path 46 above the storage tank 44, and at the other end to the side of the furnace body 12. This allows the fluid medium 13 that has exited the outlet 43B of the circulation elevator 43 to be returned to the furnace body 12 via the third transport path 47. Although not shown in the figures, the circulation path 40 may further include a switching unit (valve, etc.) to switch whether the fluid medium 13 that has exited the outlet 43B of the circulation elevator 43 is directed to the storage tank 44 or to the furnace body 12.

[0039] <Method for recovering fluidized medium in a fluidized bed furnace> This section describes a method for recovering the fluidized medium 13 in a fluidized bed furnace 10 according to this embodiment. This recovery method is used to recover the fluidized medium 13 from inside the furnace body 12 when the fluidized bed furnace 10 is stopped, for example, during maintenance of the fluidized bed furnace 10. The fluidized medium recovery method includes an extraction step in which the aeration mechanism A is stopped and the fluidized medium 13 supported on the furnace bottom plate 16 is allowed to flow into the discharge port 16a and extracted, and a recovery step in which the fluidized medium 13 remaining on the furnace bottom plate 16 after the extraction step is recovered. In the extraction step, the fluidized medium 13 is deposited on the furnace bottom plate 16 by the accumulation mechanism B (damming member 16b). In this embodiment, in this extraction step, the fluidized medium 13 remaining on the furnace bottom plate 16 is deposited by the accumulation mechanism B (damming member 16b) to form an accumulation layer 13a. Furthermore, the fluid medium 13 is deposited in the deposited layer 13a such that its thickness is greater on the side of the discharge port 16a than on the central part C of the radial direction R extending from the center X in a plan view of the furnace body 12 to the inner surface 12a of the furnace body 12 (see Figures 4-5).

[0040] As shown in Figure 1, before maintenance of the fluidized bed furnace 10, i.e., during steady-state operation of the fluidized bed furnace 10, the fluidized medium 13 is in a fluidized state due to the fluidizing gas (e.g., air) supplied through the diffuser pipe 19, and the material to be processed is supplied into the furnace body 12 from the supply port 14. This material to be processed is heated by the fluidized medium 13 in the furnace body 12 and thermally decomposed into combustible gas, unburned material, and ash. Here, the material to be processed contains a considerable amount of valuable metals such as precious metals (gold, silver, copper, etc.) and heavy metals (lead, zinc, etc.).

[0041] The combustible gas generated in the fluidized bed furnace 10 flows into the swirling flow melting furnace 20 through the duct 30 along with unburned material and ash. In the swirling flow melting furnace 20, the combustible gas and unburned material are completely combusted and the ash melts. During this steady-state operation, the circulation path 40 is activated to remove the fluidized medium 13 filled in the furnace body 12 along with the non-combustible material from the furnace, and to return the fluidized medium 13 from which the non-combustible material has been removed back into the furnace body 12.

[0042] Next, when it is time for maintenance of the fluidized bed furnace 10, first the supply of the material to be processed to the furnace body 12 is stopped. Subsequently, the supply of fluidizing gas to the wind box 18 is stopped. In other words, the aeration mechanism A is stopped. After that, an extraction process is performed in which the fluidized medium 13 filled in the furnace body 12 is extracted to the outside of the furnace body 12.

[0043] In the extraction process, the fluid medium 13 filled inside the furnace body 12 is drawn out of the furnace body 12 by flowing it into the discharge port 16a. Specifically, by rotating the extraction screw 41, the fluid medium 13 filled inside the furnace body 12 is drawn out of the furnace body 12 through the discharge port 16a and the discharge pipe 15 that communicates with the discharge port 16a.

[0044] The fluid medium 13 extracted from the furnace is separated from non-combustible materials by a classifier 42, transported upward by a circulating elevator 43, and then stored in a storage tank 44. In other words, during the extraction process, the fluid medium 13 extracted from the furnace body 12 is not returned to the furnace body 12, but is all stored in the storage tank 44.

[0045] Figure 5 shows the inside of the furnace body 12 after the extraction process (the area near the furnace bottom plate 16). As described above, the furnace bottom plate 16 is inclined downward toward the discharge port 16a at an angle θ smaller than the angle of repose of the fluid medium 13. For this reason, not all of the fluid medium 13 inside the furnace body 12 is extracted out of the furnace during the extraction process, and some of the fluid medium 13 remains on the furnace bottom plate 16 after the extraction process, forming a deposit layer 13a.

[0046] In this embodiment, the furnace bottom plate 16 also has a damming member 16b provided at the opening periphery, which is the end of the furnace bottom plate 16 on the outlet 16a side, as a fluid medium accumulation mechanism B for the fluid medium 13 (see Figures 2 and 3). Therefore, in the extraction process, the inflow of the fluid medium 13 into the outlet 16a is prevented by the damming member 16b, so a large amount of fluid medium 13 remains on the furnace bottom plate 16 as an accumulated layer 13a. In addition, in this embodiment, in this extraction process, the fluid medium 13 is accumulated such that the thickness of the accumulated layer 13a of the fluid medium 13 remaining on the furnace bottom plate 16 by the accumulation mechanism B (damming member 16b) is greater on the outlet 16a side than on the central part C of the radial direction R extending from the center X to the inner surface 12a of the furnace body 12, with the center X of the region where the furnace bottom plate 16 is located as the reference point in a plan view of the furnace body 12 (see Figures 2 and 5). Specifically, as shown in Figure 2, the thickness of the deposit layer 13a is greater on the side of the discharge port 16a than the thickness T1 on the side of the discharge port 16a, compared to the thickness T2 and T3 in the central part C of the radial direction R extending from the center X to the inner surface 12a of the furnace body 12. In addition, the deposit layer 13a on the side of the discharge port 16a acts as resistance to the fluid medium 13 moving towards the discharge port 16a along the surface 16c of the furnace bottom plate 16, making it difficult for the fluid medium 13 to flow toward the discharge port 16a. As a result, the furnace bottom plate 16 can retain a large amount of fluid medium 13 in the area near the discharge port 16a. Consequently, valuable metals can be efficiently recovered from the fluid medium 13 (deposit layer 13a) remaining on the furnace bottom plate 16.

[0047] As shown in Figure 4, in this embodiment, the damming member 16b is formed in a circular shape in plan view at the end (opening edge) on the outlet 16a side of the group of diffusers located on the innermost side of the group of diffusers arranged concentrically by a plurality of diffusers 19. As shown in Figure 2, the height of this damming member 16b, relative to the surface 16c of the furnace bottom plate 16, is smaller than the height of the diffusers 19. In particular, since the damming member 16b is located lower than the U-shaped pipe portion 19b of the diffusers 19, the deposition mechanism B can efficiently form the deposition layer 13a without hindering the aeration process of the aeration mechanism A during operation. The damming member 16b may be configured to move in and out between a state where it protrudes from the surface 16c of the furnace bottom plate 16 and a state where it does not protrude from the surface 16c of the furnace bottom plate 16.

[0048] Thus, of the fluidized medium 13 contained in the furnace body 12, the majority (for example, more than 90%) is sent to the storage tank 44 in the extraction process, and the remainder remains inside the furnace body 12. Here, it is known that in a fluidized bed furnace 10, the fluidized medium 13 remaining in the furnace body 12 after the extraction process contains valuable metals (gold, silver, copper, lead, zinc, etc.) derived from the material being processed in high concentrations.

[0049] Therefore, in the recovery process following the extraction process, the fluid medium 13 remaining in the furnace body 12 is recovered separately from the fluid medium 13 extracted from the furnace body 12 in the extraction process (the fluid medium 13 stored in the storage tank 44). Specifically, after the extraction process is completed, an operator enters the furnace body 12 and collects the fluid medium 13 remaining on the furnace bottom plate 16, thereby directly recovering the fluid medium 13 from inside the furnace body 12.

[0050] Subsequently, the worker performs maintenance work such as cleaning and inspecting the inside of the furnace body 12. Note that cleaning and inspection of the furnace may be performed before recovering the remaining fluid medium 13, or the recovery of the fluid medium 13 remaining on the furnace bottom plate 16 and the maintenance work inside the furnace body 12 may be performed concurrently. In other words, the recovery process should be carried out after stopping the aeration mechanism A.

[0051] Thus, in the recovery method according to this embodiment, the fluidized bed furnace 10 is used to recover the fluidized medium 13 containing a high concentration of valuable metals derived from the material to be processed, by utilizing the timing of maintenance of the fluidized bed furnace 10.

[0052] Finally, the valuable metals are separated from the fluid medium 13 recovered in the recovery process. Specifically, the valuable metals contained in the fluid medium 13 are separated from the fluid medium 13 by methods such as heat treatment, chemical treatment, or physical separation. Examples of heat treatments include melting (smelting), calcination, or chlorination. Examples of chemical treatments include solvent extraction with acids, etc. Examples of physical separations include wind separation, magnetic separation, vibration separation, eddy current separation, electrostatic separation, or specific gravity separation.

[0053] As described above, since the fluidized bed furnace 10 has a deposition mechanism B, when the aeration mechanism A is stopped and the fluidized medium 13 filled in the furnace body 12 is withdrawn from the outlet 16a, a large amount of the fluidized medium 13 remains on the furnace bottom plate 16 as a deposition layer 13a. Furthermore, since the deposition mechanism B is located in a different position from the aeration mechanism A, the deposition mechanism B can efficiently form the deposition layer 13a without hindering the aeration treatment of the aeration mechanism A during operation. As a result, while the fluidized medium 13 containing noncombustible material is withdrawn from the outlet 16a, a larger amount of the fluidized medium 13 can remain on the furnace bottom plate 16 compared to when the deposition mechanism B is not provided. Consequently, valuable metals can be efficiently recovered from the fluidized medium 13 remaining on the furnace bottom plate 16.

[0054] Since the damming member 16b, which acts as the deposition mechanism B, is provided at the end (periphery of the opening) of the furnace bottom plate 16 on the outlet 16a side, the damming member 16b prevents the fluid medium 13 from flowing into the outlet 16a due to gravity. As a result, the fluid medium 13 that is dammed by the damming member 16b acts as resistance to the fluid medium 13 moving along the surface 16c of the furnace bottom plate 16 toward the outlet 16a, making it possible to deposit a large amount of fluid medium 13 on the furnace bottom plate 16 and form a deposited layer 13a from the fluid medium 13. Furthermore, since the damming member 16b (deposition mechanism B) only needs to be provided at the end (periphery of the opening) of the furnace bottom plate 16 on the outlet 16a side, it can be retrofitted to an existing fluidized bed furnace 10, making it efficient.

[0055] [Second Embodiment] The fluidized bed furnace 10 of the second embodiment will be described with reference to Figure 6. Below, only the differences from the first embodiment will be described. The method for recovering the fluidized medium 13 in the fluidized bed furnace 10 according to the second embodiment is basically the same as the method for recovering the fluidized medium 13 in the fluidized bed furnace 10 according to the first embodiment.

[0056] Figure 6 schematically shows the configuration of the furnace bottom plate 16 in the fluidized bed furnace 10 of the second embodiment. In the fluidized bed furnace 10 of the second embodiment, the stacking mechanism B is provided with a plurality of stepped portions 50 on the surface 16c of the furnace bottom plate 16 such that the end of the furnace bottom plate 16 on the discharge port 16a side is the lowest. The plurality of stepped portions 50 are configured by alternately providing flat portions 51 and rising portions 52 from the end on the discharge port 16a side. The furnace bottom plate 16 is formed with a horizontal surface (flat portion 51a) that is not inclined at the end (surface 16c) on the discharge port 16a side.

[0057] Thus, as the deposition mechanism B, if multiple stepped sections 50 are provided on the surface of the furnace bottom plate 16 such that the end of the furnace bottom plate 16 on the discharge port 16a side is the lowest, the fluid medium 13 will remain and deposit on the multiple stepped sections 50 of the furnace bottom plate 16, forming a deposit layer 13a of a large amount of fluid medium 13 around the multiple stepped sections 50. Furthermore, if there is a place where the thickness of the deposit layer 13a is larger in any of the flat sections 51 of the multiple stepped sections 50, the thicker deposit layer 13a will act as a damming function for the fluid medium 13. As a result, valuable metals can be efficiently recovered from the fluid medium 13 remaining on the furnace bottom plate 16.

[0058] [Modification 1 of the second embodiment] In the first modified example of the second embodiment, as shown in Figure 7, the stacking mechanism B is configured such that a plurality of stepped sections 50 are alternately provided with inclined surfaces 53 and rising sections 52 from the end of the furnace bottom plate 16 on the discharge port 16a side. The furnace bottom plate 16 is formed by a flat section 53a with an inclined end (surface 16c) on the discharge port 16a side. The inclination angle of this inclined surface 53 (the inclination angle of the furnace bottom plate 16) is smaller than the angle of repose of the fluid medium 13 (30 to 40 degrees). Furthermore, since the fluid medium 13 moves down the stepped sections 50, the inclination angle of the inclined surface 53 may be smaller than the inclination angle (angle θ) of the furnace bottom plate 16 without stepped sections 50 as in the first embodiment, and is typically between 5 and 20 degrees.

[0059] [Modification 2 of the second embodiment] In the modified example 2 of the second embodiment, as shown in Figure 8, the deposition mechanism B has multiple stepped portions 50 provided on the surface 16c of the furnace bottom plate 16 such that the end of the furnace bottom plate 16 on the outlet 16a side is the lowest. The multiple stepped portions 50 are configured by sequentially providing a flat portion 51 and an inclined surface 53 from the end of the furnace bottom plate 16 on the outlet 16a side. The end (surface 16c) of the furnace bottom plate 16 on the outlet 16a side is formed as a horizontal surface (flat portion 51). When the end (surface 16c) of the furnace bottom plate 16 on the outlet 16a side is formed as a horizontal surface (flat portion 51), the fluid medium 13 remains and deposits on the flat portion 51 of the furnace bottom plate 16. In addition, the thickness of the deposited layer 13a deposited on the flat portion 51, which is the end of the furnace bottom plate 16 closest to the outlet 16a, becomes larger, and the deposited layer 13a formed at the end closest to the outlet 16a exhibits a damming function for the fluid medium 13.

[0060] [Third Embodiment] The fluidized bed furnace 10 of the third embodiment will be described with reference to Figures 9 and 10. Hereinafter, only the differences from the first embodiment will be described. The method for recovering the fluidized medium 13 in the fluidized bed furnace 10 according to the third embodiment is basically the same as the method for recovering the fluidized medium 13 in the fluidized bed furnace 10 according to the first embodiment.

[0061] As shown in Figures 9 and 10, in the fluidized bed furnace 10 of the third embodiment, the aeration mechanism A includes a plurality of aeration pipes 19 protruding from the surface 16c of the furnace bottom plate 16, and the accumulation mechanism B consists of projections 55 (an example of a damming member) provided on the surface 16c of the furnace bottom plate 16 at positions where the aeration pipes 19 are not arranged.

[0062] Specifically, the projection 55 is positioned between a plurality of adjacent diffusers 19 in the radial or circumferential direction of the furnace bottom plate 16. The projection 55 is formed in a rectangular shape in plan view, for example, and is positioned so that its longitudinal direction intersects the radial direction of the furnace bottom plate 16. This projection 55 is located lower than the U-shaped pipe portion 19b of the diffuser 19. Therefore, the deposition mechanism B can efficiently form the deposition layer 13a without hindering the aeration process of the aeration mechanism A during operation. Note that the projection 55 may also be arc-shaped or circular in plan view, and is not particularly limited.

[0063] Thus, the projection 55, which is provided in a position where the diffuser pipe 19 is not located as the deposition mechanism B, makes it difficult for the fluid medium 13 to flow toward the outlet 16a on the furnace bottom plate 16, and makes it more likely to remain on the furnace bottom plate 16. This projection 55 acts as resistance to the fluid medium 13 moving toward the outlet 16a along the surface 16c of the furnace bottom plate 16, making it difficult for the fluid medium 13 to flow toward the outlet 16a. In other words, the fluid medium 13 remains and deposits on the projection 55 of the furnace bottom plate 16, and a large amount of fluid medium 13 around the projection 55 forms a deposition layer 13a.

[0064] [Another embodiment] (1) In the above embodiment, an example was shown in which, in the recovery process, an operator enters the furnace body 12 and collects the fluid medium 13 remaining on the furnace bottom plate 16, thereby directly recovering the fluid medium 13 from inside the furnace body 12. Alternatively, in the recovery process, the fluid medium 13 remaining on the furnace bottom plate 16 may be recovered along the first transport path 45. For example, an operator may enter the furnace body 12, drop the fluid medium 13 remaining on the furnace bottom plate 16 into the discharge pipe 15 from the discharge port 16a, and then rotate the extraction screw 41 to recover the fluid medium 13.

[0065] As a result, the fluid medium 13 remaining on the furnace bottom plate 16 after the extraction process can be discharged outside the furnace body 12 and then recovered at a location different from the storage tank 44 (partway along the first transport route 45). Consequently, the fluid medium 13 remaining on the furnace bottom plate 16 can be recovered separately from the fluid medium 13 stored in the storage tank 44 during the extraction process.

[0066] In addition, a recovery port for the fluid medium 13 remaining on the furnace bottom plate 16 may be provided at another location in the circulation path 40 (for example, the circulation elevator 43).

[0067] (2) In the above embodiment, an example was shown in which the diffuser pipe 19 protrudes upward from the furnace bottom plate 16. However, the fluidized bed furnace 10 may also be configured such that the diffuser pipe 19 does not protrude upward from the furnace bottom plate 16. In other words, the diffuser pipe 19 ejects the fluidizing gas from the surface 16c of the furnace bottom plate 16.

[0068] (3) In the above embodiment, an example was shown in which the discharge port 16a is located on the central side in a plan view of the furnace body 12, that is, on the inner circumference side of the furnace bottom plate 16. However, as shown in Figures 11 and 12, the fluidized bed furnace 10 may have the discharge port 16a located on the outer circumference side of the furnace bottom plate 16 in a plan view of the furnace body 12.

[0069] (4) In the recovery process, when the worker drops the fluidizing medium 13 remaining on the furnace bottom plate 16 into the discharge pipe 15, the fluidizing gas may be supplied from the diffuser pipe 19 to drop the fluidizing medium 13 remaining on the furnace bottom plate 16 into the discharge pipe 15.

[0070] (5) In the above embodiment, an example was shown in which a fluidized bed gasifier 10 that gasifies the material to be processed is used as the fluidized bed furnace 10, but a fluidized bed incinerator that incinerates the material to be processed can also be used as the fluidized bed furnace 10.

[0071] (6) In the above embodiment, an example was shown in which the furnace body 12 of the fluidized bed furnace 10 is formed in a cylindrical shape, but the furnace body 12 of the fluidized bed furnace 10 may also be in a rectangular tubular shape. [Industrial applicability]

[0072] The present invention is widely applicable to fluidized bed furnaces that incinerate or gasify materials containing valuable metals, and to methods for recovering fluidized media in fluidized bed furnaces. [Explanation of symbols]

[0073] 1:Fluidized bed furnace equipment 10: Fluidized bed gasifier (fluidized bed furnace) 12: Furnace body 13: Fluid medium 13a: Sedimentary layer 16: Furnace bottom plate 16a: Outlet 16b: Damming member 16c: surface 19: Diffuser pipe 19a: Straight pipe section 19b: U-shaped tube part 40: Circulation route 43: Circulating elevator 44: Storage tank 45: First transport route 46: Second transport route 47: Third transport route 50: Stepped section 51,51a,53a: Flat part 52: Upright section 53: Inclined part 55:Protrusion A: Aeration mechanism B:Deposition mechanism C: Central part R: Radial direction T1, T2, T3: Thickness X: Center θ: Angle

Claims

1. A fluidized bed furnace that incinerates or gasifies materials containing valuable metals, A furnace body containing a fluid medium, The system includes a diffusion mechanism for blowing a fluidizing gas to make the fluid medium flow, The furnace body has a furnace bottom plate that supports the fluid medium, and a discharge port provided adjacent to the furnace bottom plate that can discharge the fluid medium. The furnace bottom plate has a deposition mechanism, located at a different position from the aeration mechanism, that deposits the remaining fluid medium to form a deposition layer when the aeration mechanism is stopped and the fluid medium is extracted from the outlet. The aforementioned accumulation mechanism is a fluidized bed furnace, comprising a damming member provided on the furnace bottom plate to prevent the fluidized medium from flowing into the discharge port.

2. The fluidized bed furnace according to claim 1, wherein the damming member is provided at the end of the furnace bottom plate on the outlet side.

3. A fluidized bed furnace for incinerating or gasifying a material containing valuable metals, A furnace body containing a fluid medium, The system includes a diffusion mechanism for blowing a fluidizing gas to make the fluid medium flow, The furnace body has a furnace bottom plate that supports the fluid medium, and a discharge port provided adjacent to the furnace bottom plate that can discharge the fluid medium. The furnace bottom plate has a deposition mechanism, located at a different position from the aeration mechanism, that deposits the remaining fluid medium to form a deposition layer when the aeration mechanism is stopped and the fluid medium is extracted from the outlet. The aforementioned deposition mechanism is a fluidized bed furnace in which a plurality of stepped portions are provided on the surface of the furnace bottom plate such that the end of the furnace bottom plate on the discharge side is the lowest.

4. The fluidized bed furnace according to claim 3, wherein the end of the furnace bottom plate on the discharge side is formed as a horizontal plane.

5. The fluidized bed furnace according to claim 1 or 3, wherein the aeration mechanism includes a plurality of aeration pipes protruding from the surface of the furnace bottom plate.

6. The fluidized bed furnace according to claim 1 or 3, wherein all or part of the furnace bottom plate is inclined at an angle smaller than the angle of repose of the fluidized medium.

7. A fluidized medium recovery method for recovering a fluidized medium by stopping a fluidized bed furnace that incinerates or gasifies a material containing valuable metals, The aforementioned fluidized bed furnace is A furnace body containing the aforementioned fluid medium, The system includes a diffusion mechanism for blowing a fluidizing gas to make the fluid medium flow, The furnace body has a furnace bottom plate that supports the fluid medium, and a discharge port provided adjacent to the furnace bottom plate that can discharge the fluid medium. The furnace bottom plate has a deposition mechanism, located at a different position from the aeration mechanism, that deposits the remaining fluid medium to form a deposition layer when the aeration mechanism is stopped and the fluid medium is extracted from the discharge port. The aforementioned accumulation mechanism is provided on the furnace bottom plate and consists of a damming member that prevents the fluid medium from flowing into the discharge port. A extraction step in which the aeration mechanism is stopped and the fluid medium supported on the furnace bottom plate is allowed to flow into the discharge port and extracted, The process includes a recovery step of recovering the fluid medium remaining on the furnace bottom plate after the extraction step, The extraction step is a method for recovering a fluid medium, in which the fluid medium is deposited on the furnace bottom plate by the deposition mechanism.

8. A method for recovering a fluidized medium by stopping a fluidized bed furnace that incinerates or gasifies a material containing valuable metals, The aforementioned fluidized bed furnace is A furnace body containing the aforementioned fluid medium, The system includes a diffusion mechanism for blowing a fluidizing gas to make the fluid medium flow, The furnace body has a furnace bottom plate that supports the fluid medium, and a discharge port provided adjacent to the furnace bottom plate that can discharge the fluid medium. The furnace bottom plate has a deposition mechanism, located at a different position from the aeration mechanism, that deposits the remaining fluid medium to form a deposition layer when the aeration mechanism is stopped and the fluid medium is extracted from the discharge port. The aforementioned deposition mechanism is provided with a plurality of stepped portions on the surface of the furnace bottom plate such that the end of the furnace bottom plate on the discharge port side is the lowest. A extraction step in which the aeration mechanism is stopped and the fluid medium supported on the furnace bottom plate is allowed to flow into the discharge port and extracted, The process includes a recovery step of recovering the fluid medium remaining on the furnace bottom plate after the extraction step, The extraction step is a method for recovering a fluid medium, in which the fluid medium is deposited on the furnace bottom plate by the deposition mechanism.

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