Metal recovery system

Abstract

A metal recovery system according to the present invention recovers metal from a metal-containing material. The system comprises a heating furnace for heating the metal-containing material, a supply means for supplying superheated steam or inert gas to the heating furnace, an atmosphere-opened gas discharge part for discharging the gas in the heating furnace to the outside of the heating furnace, and a gas treatment device for treating the gas discharged from the gas discharge part, wherein the inside of the heating furnace is maintained at normal pressure or positive pressure. The metal recovery system makes it possible to suppress oxidation of metal, which is a cause of reduction in metal recovery efficiency.

Description

Metal Recovery System

[0001] The present invention relates to a metal recovery system for recovering metals from items containing metals (hereinafter referred to as "metal-containing items").

[0002] Since the adoption of the Sustainable Development Goals (SDGs) at the United Nations Summit in September 2015, efforts to achieve these goals have been required. Industries that handle metal-containing materials are being called upon to recycle and effectively utilize the metals contained in these materials.

[0003] Conventionally, a method for recovering metals from metal-containing materials has been known in which organic matter is removed by superheated steam supplied into the inner cylinder of a heating device, and then the metal is recovered (Patent Document 1).

[0004] Japanese Patent Application Laid-Open No. 2008-194618

[0005] In a metal recovery device that removes organic matter using superheated steam, if outside air flows into the inner cylinder of the heating device, the metal may be oxidized by the outside air, resulting in a decrease in metal recovery efficiency.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a metal recovery system capable of suppressing oxidation of metals.

[0007] The metal recovery system of the present invention is a system for recovering metals from metal-containing materials, and includes a heating furnace for heating the metal-containing materials, a supply means for supplying superheated steam or an inert gas to the heating furnace, a gas exhaust section open to the atmosphere for exhausting gas from the heating furnace to the outside, and a gas treatment device for treating the gas exhausted from the gas exhaust section, and the inside of the heating furnace is maintained at normal pressure or positive pressure.

[0008] According to the present invention, by opening the gas exhaust port to the atmosphere and maintaining the interior of the heating furnace at normal pressure or positive pressure, it is possible to prevent outside air from flowing into the heating furnace and suppress oxidation of the metal.

[0009] 1 is a schematic explanatory diagram showing an example of a metal recovery system. It is an explanatory diagram showing an example of a dust collection hood and a control damper. (a) is an explanatory diagram of input / output signals when a control device controls a control damper, (b) is an explanatory diagram of input / output signals when a control device controls an induction blower, and (c) is an explanatory diagram of input / output signals when a control device controls a supply device.

[0010] (Embodiment) An example of an embodiment of the present invention will be described with reference to the drawings. The metal recovery system of the present invention is a system for recovering metals from metal-containing materials. In this application, metal-containing materials refer to materials containing metals, and include, for example, metal cans, metal-coated packaging materials, shredder residue, etc. More specifically, they include waste and scraps such as aluminum cans, metal-coated paper cartons, and automobile shredder residue (ASR).

[0011] As an example, a metal recovery system 100 shown in FIG. 1 includes a heating device 30 , a supplying device 41 , an exhausting device 42 , a gas treating device 50 , and a control device 80 .

[0012] [Heating Device] The heating device 30 is a device that heats a metal-containing material with superheated steam (in this embodiment, superheated steam is used as an example) to separate it into organic components and metals. As an example, the heating device 30 shown in Figure 1 includes a heating furnace 10 that heats the metal-containing material and a supply means (in this embodiment, superheated steam supply means 20) that supplies superheated steam to the heating furnace 10.

[0013] The heating furnace 10 of this embodiment includes an inner cylinder 11 into which the metal-containing material to be treated is supplied, and an outer cylinder 12 provided on the outer periphery of the inner cylinder 11 .

[0014] An outer cylinder seal 14 is provided in the gap between the sliding portions of the inner cylinder 11 and the outer cylinder 12 to prevent condensation and other problems caused by the heated air leaking out of the outer cylinder 12. The outer cylinder seal 14 may be, for example, a sheet with a leaf spring sandwiched inside. Alternatively, a heat-resistant sheet or insulating material may be used for the outer cylinder seal 14. In either case, it is necessary to use a material that is heat-resistant enough to withstand the temperature inside the heated outer cylinder 12.

[0015] The inner cylinder 11 functions as a pyrolysis furnace for thermally decomposing metal-containing materials. The inner cylinder 11 can be made of, for example, heat-resistant stainless steel. As shown in Fig. 1, the inner cylinder 11 in this embodiment has a horizontally elongated cylindrical shape and is rotatably supported by support devices 15 provided at intervals near both ends in the longitudinal direction.

[0016] An introduction pipe 16 is provided within the inner cylinder 11 to introduce superheated steam produced by superheated steam supply means 20, which will be described later, into the inner cylinder 11. A plurality of ejection holes 16a are provided in the portion of the introduction pipe 16 located within the inner cylinder 11, so that the superheated steam supplied from the superheated steam supply means 20 is ejected into the inner cylinder 11 from the ejection holes 16a.

[0017] The superheated steam supply means 20 is a device that generates superheated steam and supplies it into the inner cylinder 11. The superheated steam supply means 20 in this embodiment includes a boiler 21 that generates a required amount of steam, and a superheated steam generator 22 that heats the steam to a temperature required for treating the object to be treated. A water supply device 23 is connected to the boiler 21, and water is supplied from the water supply device 23 to the boiler 21.

[0018] In the superheated steam supply means 20, water at room temperature (for example, about 20°C) is supplied from a water supply device 23 to a boiler 21, and the water is heated in the boiler 21 to become steam at about 140°C. The steam generated in the boiler 21 is further heated in a superheated steam generator 22 to become superheated steam at 300°C or higher, and is supplied into the inner cylinder 11 through an inlet pipe 16.

[0019] Various types of boilers, including a burner-heated small once-through steam boiler, can be used for the boiler 21. Also, various types of devices, including a burner-heated superheater that can be used for a second-class pressure vessel, can be used for the superheated steam generator 22.

[0020] In addition, the boiler 21 may use a liquefied natural gas (LNG), liquefied petroleum gas (LPG), or liquid combustion burner, as well as an electric, hydrogen, or ammonia combustion burner.

[0021] In this embodiment, an example is given in which the inner cylinder 11 is filled with superheated steam, but the inner cylinder 11 can also be filled with an inert gas instead of superheated steam.

[0022] The inert gas referred to here is a so-called inert gas that is chemically stable and does not easily react with other elements or compounds, and includes, for example, helium, neon, argon, krypton, xenon, radon, nitrogen, carbon dioxide, or fluorocarbon (excluding flammable gases), etc. When filling the inner cylinder 11 with an inert gas, an inert gas supply means can be used as the supply means instead of the superheated steam supply means 20.

[0023] In the inner cylinder 11, organic matter adhering to the metal-containing material is removed in a superheated steam atmosphere, and metals can be continuously recovered in a short time after the organic matter has been removed. By introducing superheated steam into the inner cylinder 11 and filling it with the steam, oxidation of the metal can be suppressed, and the oxidation reaction of the metal-containing material can be minimized.

[0024] Although not shown in the figure, a scraper (stirring tool) for stirring the metal-containing material to be treated is provided inside the inner cylinder 11, so that the metal-containing material can be continuously treated while being stirred. Note that, although this embodiment shows an example in which the inner cylinder 11 is of a rotating type, the inner cylinder 11 can also be replaced by a fixed box chamber or the like.

[0025] The outer cylinder 12 functions as a heating device for heating the inner cylinder 11. As shown in Fig. 1, the outer cylinder 12 of this embodiment is a horizontally long cylindrical member similar to the inner cylinder 11. Unlike the inner cylinder 11, the outer cylinder 12 is configured not to rotate.

[0026] An electric heater 12a is built into the outer cylinder 12 as a heat source for heating the inner cylinder 11 and maintaining the temperature inside the inner cylinder 11. By using the electric heater 12a as a heat source, it is possible to control the temperature inside the inner cylinder 11 with high precision. Instead of a heating method using the electric heater 12a, an indirect heating method using burner heating or waste heat (hot air) can also be adopted.

[0027] The outer cylinder 12 is shorter than the inner cylinder 11, and both longitudinal ends of the inner cylinder 11 protrude outward beyond both longitudinal ends of the outer cylinder 12. A supply hood 18 is provided at one longitudinal end of the inner cylinder 11, and a discharge hood 19 is provided at the other longitudinal end.

[0028] Inner cylinder seals 17 are provided in the gap between the sliding parts of the rotating inner cylinder 11 and the non-rotating supply hood 18 and in the gap between the sliding parts of the rotating inner cylinder 11 and the non-rotating exhaust hood 19 to prevent external air (fresh air) from flowing in.

[0029] In this embodiment, the inner tube seals 17 include a supply side inner tube seal 17a arranged in the gap between the sliding parts of the inner tube 11 and the supply hood 18, and a discharge side inner tube seal 17b arranged in the gap between the sliding parts of the inner tube 11 and the discharge hood 19.

[0030] A so-called metal seal can be used for the inner cylinder seal 17. Specifically, a sealing member having a structure in which metal surfaces are rubbed against each other, with grease filled as a lubricant at the contact portion of the sliding parts of the inner cylinder 11 and the supply hood 18 or the contact portion of the sliding parts of the inner cylinder 11 and the exhaust hood 19, can be used.

[0031] In addition to a metal seal, a V-ring type seal packing, a carbon seal, a seal member with a gland packing seal structure, etc. may also be used for the inner cylinder seal 17. When a V-ring type seal packing or a carbon seal is used, it is preferable to perform nitrogen purging.

[0032] The exhaust hood 19 is equipped with a gas exhaust section 19a having an exhaust port for exhausting the gas in the inner cylinder 11 to the outside of the inner cylinder 11, and a treated material exhaust section 19b for exhausting the treated material, which is the metal-containing material treated in the inner cylinder 11. The gas exhaust section 19a is provided on the upper end side of the exhaust hood 19, and the treated material exhaust section 19b is provided on the lower end side of the exhaust hood 19. Note that the gas exhaust section 19a does not include any gaps through which gas may unintentionally leak.

[0033] A supply device 41 is provided upstream of the heating device 30 to supply the metal-containing material into the inner cylinder 11 while isolating it from the outside air. Also, a discharge device 42 is provided downstream of the heating device 30 to discharge the processed material discharged from the processed material discharge section 19b of the discharge hood 19 outside the heating device 30 while isolating it from the outside air.

[0034] The supply device 41 is a device that supplies the metal-containing material to be treated into the inner cylinder 11. The supply device 41 in this embodiment includes a two-stage damper (feed-side two-stage damper) 41a and a chute 41b. The two-stage damper 41a includes two boxes stacked in two stages. Each box is provided with a damper, and by alternately opening and closing the dampers of both boxes, the metal-containing material can be fed into the inner cylinder 11 while blocking outside air.

[0035] In this embodiment, a gas filling machine 41c is connected to the lower box of the two-stage damper 41a, so that the lower box can be filled with an inert gas such as nitrogen gas. By filling the lower box with an inert gas, the amount of air that flows in together with the metal-containing material to be treated can be minimized, and the oxidation reaction within the heating device 30 can be minimized.

[0036] In this embodiment, the metal-containing material discharged from the two-stage damper 41a is supplied to the inner cylinder 11 through the chute 41b, but a screw feeder, a vibrating feeder, or the like can also be used to supply the metal-containing material into the inner cylinder 11.

[0037] The discharge device 42 is a device that discharges the processed material from the heating device 30 after processing in the heating device 30 has been completed. The discharge device 42 of this embodiment is equipped with a two-stage damper similar to that of the supply device 41. The two-stage damper (discharge-side two-stage damper) 42a is equipped with two boxes stacked in two stages. Each box is provided with a damper, and by alternately opening and closing the dampers of both boxes, it is possible to discharge the metal-containing material while blocking the outside air.

[0038] In this embodiment, the discharge device 42 is provided with a two-stage damper as an example, but depending on the shape of the object to be treated (processed material), a rotary valve, a slide gate, or the like can also be used instead of the two-stage damper.

[0039] The heating device of this embodiment configured as described above is a device for heating a metal-containing material in order to recover metals from the metal-containing material, and can be considered as a single invention, comprising a heating furnace for heating the metal-containing material, a supply means for supplying superheated steam or an inert gas to the heating furnace, and a gas exhaust section open to the atmosphere for exhausting gas from within the heating furnace to the outside of the heating furnace, with the interior of the heating furnace being maintained at normal pressure or positive pressure.

[0040] [Gas Treatment Device] Next, the gas treatment device 50 will be described. The gas treatment device 50 is a device that recovers and treats the gas discharged from the heating device 30. The gas treatment device 50 is provided downstream of the heating device 30.

[0041] The gas treatment device 50 of this embodiment includes a dust collection hood 51 that takes in gas discharged from the gas exhaust section 19a that is open to the atmosphere, an induction blower (suction means) 52 that sucks in the gas discharged from the gas exhaust section 19a, and a dust collection device (dust collection means) 53 that collects particles in the gas sucked in by the induction blower 52.

[0042] 2, the dust collection hood 51 is a funnel-shaped member that tapers from an intake port 51a that takes in gas discharged from the gas discharge section 19a (FIG. 1) that is open to the atmosphere toward an outlet port 51b that discharges the gas. The dust collection hood 51 can be made of heat-resistant stainless steel or the like.

[0043] In this embodiment, the opening area of ​​the intake port 51a of the dust collection hood 51 is made larger than the opening area of ​​the exhaust port of the gas exhaust section 19a. This has the advantage that the gas exhausted from the gas exhaust section 19a is reliably collected by the dust collection hood 51 and is less likely to leak around the dust collection hood 51.

[0044] 2, a control damper 54 equipped with a valve for adjusting the gas flow rate is connected to the outlet 51b of the dust collecting hood 51. A control motor 55 that operates in response to a signal input from a control device 80 (described later) is connected to the control damper 54. The opening and closing degree of the valve of the control damper 54 is adjusted by the operation of the control motor 55.

[0045] 1, the dust collection hood 51 is provided with its intake port 51a facing the gas exhaust section 19a. In this embodiment, the gas exhaust section 19a is open to the atmosphere, and the dust collection hood 51 and the gas exhaust section 19a are not connected. Therefore, the atmosphere is always present between the dust collection hood 51 and the gas exhaust section 19a.

[0046] As in this embodiment, the gas exhaust port 19a is opened to the atmosphere to separate the heating device 30 from the gas treatment device 50, and the gas is sucked in by the induction blower 52, so that the pressure of the superheated steam atmosphere inside the inner cylinder 11 can be maintained at atmospheric pressure or higher (normal pressure or positive pressure). This allows the inner cylinder 11 to be filled with superheated steam, and prevents the air from entering the inner cylinder 11 through the inner cylinder seal 17.

[0047] Furthermore, by opening the gas exhaust section 19a to the atmosphere, it becomes difficult for superheated steam to leak from the inner cylinder seal 17 portion where pressure loss is large, and condensation does not occur at the inner cylinder seal 17 portion, enabling stable operation.

[0048] The gas discharged from the gas discharge portion 19a is taken into the dust collection hood 51 together with the surrounding air by the suction force of the induction blower 52, and moves from the intake port 51a toward the delivery port 51b.

[0049] 2, the dust collecting hood 51 of this embodiment is provided with a gas detector 81. If the amount of gas discharged from the gas discharge portion 19a is greater than the amount of gas taken into the dust collecting hood 51, there is a risk that the gas will leak out around the dust collecting hood 51. The gas detector 81 detects the gas around the dust collecting hood 51.

[0050] The detection signal from the gas detector 81 is transmitted to a control device 80, which will be described later. The control device 80 receives the detection signal and controls various devices based on the detection signal. Specific control details will be described later. The gas detector 81 may be, for example, a CO detector (carbon monoxide sensor).

[0051] A gas passage 56 through which gas passes is connected to the outlet 51b side of the control damper 54 attached to the dust collecting hood 51. The dust collector 53 is connected to the other end of the gas passage 56. The gas sent out from the outlet 51b passes through the gas passage 56 and is introduced into the dust collector 53.

[0052] The dust collector 53 is a device that processes the gas that has been sent in. In this embodiment, a ceramic filter with a heat resistance temperature of about 900°C is used as the dust collector 53. The gas taken into the dust collection hood 51 may generate heat due to a combustion reaction with the surrounding air, but by using a ceramic filter with excellent heat resistance, problems caused by the generation of heat can be prevented.

[0053] When using a ceramic filter as the dust collector 53, the above-mentioned drawbacks can be prevented by selecting one with a heat resistance temperature of 200°C or higher (preferably 200°C to 900°C, more preferably 800°C to 900°C).

[0054] It should be noted that a filter other than a ceramic filter may be used as the dust collector 53. For example, if a cooling tower or the like is provided to cool the gas to a heat-resistant temperature (for example, 200°C or less in the case of a filter cloth), a cloth-type dust collector 53 may be used instead of a ceramic filter.

[0055] A second gas treatment device 60 for treating the gas that has passed through the dust collecting hood 51 can also be provided between the dust collecting hood 51 and the dust collector 53. The second gas treatment device 60 can be composed of, for example, a secondary combustion tower (secondary heating means) 61 that heats the gas for secondary combustion, and a cooling tower (cooling means) 62 that cools the gas to a temperature that can be withstood by the dust collector 53. Both the secondary combustion tower 61 and the cooling tower 62 can be provided, or only one of them can be provided.

[0056] The secondary combustion tower 61 may be, for example, a chamber box with an inner castable structure equipped with a burner combustion device, or a heating type with an electric heater inside, while the cooling tower 62 may be, for example, a chamber box with an inner castable structure equipped with a cooling mechanism using two fluids, water and compressed air, or an indirect cooling type equipped with diluted air or an external cooling mechanism.

[0057] In addition, in the case of equipment that complies with the "Waste Disposal and Public Cleansing Law Enforcement Regulations," the secondary combustion tower 61 and cooling tower 62 are required components in principle, but in other cases, the secondary combustion tower 61 and cooling tower 62 may be installed as needed.

[0058] An induction blower 52 is provided downstream of the dust collector 53 to draw the gas discharged from the gas discharge section 19a into the dust collection hood 51. In this embodiment, a suction-type exhaust fan with an impeller rotated by a motor is used as the induction blower 52, but other induction blowers may be used as long as they can draw in the gas discharged from the gas discharge section 19a.

[0059] 1, a waste heat boiler 71 can be provided between the dust collector 53 and the induced draft blower 52. The waste heat boiler 71 recovers waste heat generated in the gas treatment process and uses it as an energy source.

[0060] By providing a waste heat boiler 71, waste heat can be effectively utilized, and CO ２ In addition to reducing emissions and achieving carbon neutrality, it can also contribute to significant reductions in fuel costs.

[0061] 1 , a water supply device 72 is connected to the waste heat boiler 71 so that water can be supplied to the waste heat boiler 71. A steam passage 73 is provided between the waste heat boiler 71 and the superheated steam generator 22 so that steam generated in the waste heat boiler 71 can be supplied to the superheated steam generator 22.

[0062] The waste heat boiler 71 and the water supply device 72 can be used in place of or together with the boiler 21 and the water supply device 23 in the superheated steam supply means 20. When the waste heat boiler 71 and the water supply device 72 are used, water at room temperature (for example, about 20°C) is supplied from the water supply device 72 to the waste heat boiler 71, and the water is heated in the waste heat boiler 71 to become steam of about 140°C. The steam generated in the waste heat boiler 71 is heated in the superheated steam generator 22 to become superheated steam of 300°C or higher and is introduced into the inner cylinder 11 through the introduction pipe 16.

[0063] In this way, by providing the waste heat boiler 71 and the water supply device 72 separately from the boiler 21 and the water supply device 23 of the superheated steam supply means 20, two routes for supplying steam to the superheated steam generator 22 are secured, and even if one route fails, there is an advantage that the entire system can continue to operate without stopping. Note that instead of providing the water supply device 72, the supply pipe that sends water from the water supply device 23 to the boiler 21 may be branched so that water can be supplied from the water supply device 23 to the waste heat boiler 71.

[0064] The gas treatment device of this embodiment configured as described above is a device used together with a heating device, and can be considered as a single invention, being arranged ahead of the gas exhaust section of the heating device in the exhaust direction, which is open to the atmosphere, and including suction means for sucking in the gas exhausted from the gas exhaust section, and dust collection means connected to the suction means for collecting particles in the gas sucked in by the suction means.

[0065] [Control Device] Next, we will explain the control device 80. The control device 80 is a device that controls various devices such as the control damper 54, the induction blower 52, and the supply device 41 based on the detection signal of the gas detector 81 described above.

[0066] When the control damper 54 is controlled by the control device 80, a gas detector 81 is connected to the input side of the control device 80, and a control motor 55 for driving the control damper 54 is connected to the output side, as shown in FIG. 3(a).

[0067] When the detection signal input from the gas detector 81 exceeds a preset upper threshold, the control device 80 outputs a signal to the control motor 55 to open the control damper 54 by a predetermined amount.

[0068] Upon receiving the signal, the control motor 55 opens the control damper 54 by a predetermined amount to widen the gas flow path, thereby increasing the amount of gas suction and reducing the amount of gas leaking out of the dust collection hood 51.

[0069] The opened control damper 54 can be closed by a desired amount when an appropriately set condition is satisfied. For example, if the detection signal input from the gas detector 81 does not reach the upper threshold for a predetermined period of time or longer, a signal to close the control damper 54 by a predetermined amount is output to the control motor 55, and the control damper 54 is closed by the predetermined amount.

[0070] When the induced draft blower 52 is controlled by the control device 80, the gas detector 81 is connected to the input side of the control device 80 and the induced draft blower 52 is connected to the output side, as shown in Figure 3(b). When the detection signal input from the gas detector 81 exceeds a preset upper threshold, the control device 80 outputs a signal to increase the rotation speed of the motor of the induced draft blower 52.

[0071] Upon receiving the signal, the induction blower 52 increases the rotation speed of the motor, thereby increasing the amount of gas suctioned by the induction blower 52. This reduces the amount of gas leaking outside the dust collection hood 51. The control of the induction blower 52 by the control device 80 is so-called inverter control, which is expected to have an energy-saving effect.

[0072] 3(c), the gas detector 81 is connected to the input side of the control device 80, and the supply device 41 is connected to the output side of the control device 80. When the detection signal input from the gas detector 81 exceeds a preset upper threshold, the control device 80 outputs a signal to reduce the amount of gas supplied by the supply device 41 or to stop the supply.

[0073] Upon receiving the signal, the supply device 41 slows down or stops the opening and closing speed of the two-stage damper 41a, thereby reducing or stopping the supply of the metal-containing material to be treated into the inner cylinder 11. This reduces the amount of combustion of the metal-containing material, reduces the amount of gas discharged from the gas discharge part 19a, and reduces the amount of gas leaking outside the dust collection hood 51.

[0074] The control damper 54, the induction blower 52, and the supply device 41 can be controlled either individually or in parallel. The control described here is merely an example, and the control device 80 can also be configured to perform other controls.

[0075] For example, an alarm can be connected to the output side of the control device 80, and when the detection signal input from the gas detector 81 exceeds a preset upper threshold, the alarm can output a signal to issue an alarm. This allows an operator to be notified of a gas leak. The control of the alarm can be performed separately from or together with the control of the control damper 54, the induction blower 52, the supply device 41, etc.

[0076] (Other Embodiments) The configuration of the above-described embodiment is an example, and the metal recovery system of the present invention is not limited to the configuration of this embodiment. The metal recovery system of the present invention can be modified, such as by adding, omitting, or replacing components, as long as the intended purpose can be achieved. The same applies to the heating device, gas treatment device, etc. that constitute the metal recovery system.

[0077] Finally, the effects obtained by the metal recovery system 100 of this embodiment will be described. Conventionally, metal recovery devices that remove organic matter using superheated steam have been known. In these conventional metal recovery devices, the inner cylinder of the heating device is filled with superheated steam, and the inner cylinder is controlled to a negative pressure.

[0078] However, when the pressure inside the inner cylinder was controlled to a negative pressure, outside air flowed into the inner cylinder, increasing the metal oxidation loss and reducing the metal recovery efficiency. To solve this problem, measures such as installing a sealing member were taken, but in reality it was difficult to completely prevent outside air from flowing into the inner cylinder.

[0079] In order to prevent outside air from flowing into the inner cylinder, it is possible to maintain normal or positive pressure inside the inner cylinder, but if normal or positive pressure is maintained inside the inner cylinder, there is a risk that gas containing organic components will leak out to the outside together with the superheated steam through the seal part, which has a large pressure loss.

[0080] The leaked gas cools in the atmosphere and condenses, sometimes dripping onto the area around the heating device. The dripping water contains gasified organic matter, which can worsen the factory environment.

[0081] Because there are such risks associated with maintaining normal or positive pressure inside the inner cylinder, it has been common practice to control the pressure inside the inner cylinder to a negative pressure, and those skilled in the art have been reluctant to maintain normal or positive pressure inside the inner cylinder 11.

[0082] In the present invention, by adopting a novel configuration in which the gas exhaust section 19a, which exhausts the gas inside the inner tube 11 to the outside of the inner tube 11, is open to the atmosphere, the problem of the outflow of gas containing organic components that occurs when the pressure inside the inner tube 11 is brought to normal or positive pressure is solved, and a higher metal recovery rate can be achieved than when negative pressure control is used.

[0083] The metal recovery system of the present invention can be suitably used as a device for recovering metals from various waste materials and scraps containing a mixture of metals and organic components, such as metal cans, metal-coated packaging materials, shredder dust, etc. The same applies to the heating device, gas treatment device, etc. that make up the metal recovery system.

[0084] REFERENCE SIGNS LIST 10 Heating furnace 11 Inner cylinder 12 Outer cylinder 12a Electric heater 14 Outer cylinder seal 15 Support device 16 Inlet pipe 16a Spout hole 17 Inner cylinder seal 17a Supply side inner cylinder seal 17b Discharge side inner cylinder seal 18 Supply hood 19 Discharge hood 19a Gas discharge section 19b Treated material discharge section 20 Superheated steam supply means 21 Boiler 22 Superheated steam generator 23 Water supply device 30 Heating device 41 Supply device 41a Two-stage damper (feed-in side two-stage damper) 41b Chute 41c Gas filling machine 42 Discharge device 42a Two-stage damper (discharge-side two-stage damper) 50 Gas treatment device 51 Dust collection hood 51a Intake port 51b Delivery port 52 Induction blower (suction means) 53 Dust collector (dust collecting means) 54 Control damper 55 Control motor 56 Gas passage 60 Second gas treatment device 61 Secondary combustion tower (secondary heating means) 62 Cooling tower (cooling means) 71 Waste heat boiler 72 Water supply device 73 Steam passage 80 Control device 81 Gas detector 100 Metal recovery system

Claims

1. A metal recovery system for recovering metals from metal-containing materials, comprising: a heating furnace for heating the metal-containing materials; a supply means for supplying superheated steam or an inert gas to the heating furnace; a gas exhaust section open to the atmosphere for exhausting gas from within the heating furnace to the outside of the heating furnace; and a gas treatment device for treating the gas exhausted from the gas exhaust section, wherein the interior of the heating furnace is maintained at normal pressure or positive pressure.

2. A metal recovery system according to claim 1, further comprising a gas detector for detecting gases around the gas treatment device.

3. A metal recovery system according to claim 1, characterized in that the gas treatment device is equipped with a dust collection hood that takes in gas discharged from a gas discharge section that is open to the atmosphere.

4. A metal recovery system according to claim 3, wherein the opening area of ​​the intake port of the dust collection hood is larger than the opening area of ​​the exhaust port of the gas exhaust section.

5. A metal recovery system according to claim 1, characterized in that the gas treatment device is equipped with a dust collection means having a heat resistance temperature of 200°C to 900°C.

6. A metal recovery system as claimed in claim 1, characterized in that a discharge-side two-stage damper is provided downstream of the heating furnace to discharge metal-containing materials that have passed through the heating furnace out of the heating furnace, and / or a feed-side two-stage damper is provided upstream of the heating furnace to feed metal-containing materials into the heating furnace.

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