Aluminum hydroxide heat treatment device

Abstract

The invention relates to non-ferrous metallurgy and can be used to dry, dehydrate and calcine powders, primarily for the heat treatment of aluminum hydroxide in the production of various grades of alumina. The apparatus comprises: an electrostatic precipitator comprising at least two zones; the dust collecting hopper is used for collecting dust from the second area of the electrostatic dust collector; a discharge hopper; the dust receiving hopper is arranged in the first area of the electrostatic dust collector; the pre-cleaning cyclone separator is connected to the collecting hopper; and a fluidized bed cooler connected to the circulating cyclone separator through an air duct through which the calcined material is discharged into the cyclone separator of the fluidized bed cooler. The dust collection hopper is connected to the discharge hopper and the pneumatic chamber pump system through channels such that the collected dust is discharged from the second zone of the electrostatic precipitator into the final product cartridge.

Description

Technical Field

[0001] The invention relates to furnace equipment for nonferrous metal metallurgy, chemical industry and building material production. It can be used for drying, dehydrating and calcining powder, and is mainly used for heat treatment of aluminum hydroxide in the production of various grades of aluminum oxide. Background Art

[0002] The drying and calcination processes are major contributors to production costs due to the high cost of fuel.

[0003] Improving the efficiency of the calciner will enable higher product yields and reduced fuel consumption.

[0004] There is an efficient prior art solution for calcining aluminum hydroxide (Vladimir Hartmann, Lugo Guzman, Olivier Hennequin, Andrew Carruthers, Michael Missalla, Hans-Werner Schmidt, Upgrade of Existing Circulating Fluidized Bed Calciners at CVGBauxilum without Compromising Product Quality, Light Metals, 2006, Edited by Travis J. Galloway. TMS (The Minerals, Metals &

[0005] Materials Society), 2006), which relates to fixed circulating fluidized bed furnaces.

[0006] The heat treatment of powdered material such as aluminum hydroxide in a fixed circulating fluidized bed furnace is as follows.

[0007] The crude aluminum hydroxide from the hopper is fed into the feed hopper by a weigh feeder and then fed into the first venturi dryer (Venturi dryer I) by a screw feeder for the first stage of heat treatment to remove external moisture. In the Venturi dryer I, the moist aluminum hydroxide is mixed with the exhaust gas heated to 350 to 380°C from the second stage of heat treatment.

[0008] The dried material from the Venturi Dryer I is fed to the dual zone electrostatic precipitator through a gas duct.

[0009] All material collected by the electrostatic precipitator is fed to a pneumatic conveyor via a screw feeder located at the bottom of the electrostatic precipitator.

[0010] After the pneumatic conveyor, the material is discharged into an airlift from which it is conveyed by compressed air through a channel into a fluidized bed discharge cyclone separator from which the material is conveyed into a second venturi dryer (Venturi Dryer II) for the second stage of thermal treatment.

[0011] The exhaust gas from the cyclone separator at 900 to 1100°C is conveyed to the Venturi Dryer II.

[0012] From the Venturi II dryer, the material is carried by the gas flow to the Venturi II cyclone separator, where the gas and material are separated. The partially dehydrated aluminum hydroxide is conveyed to the calciner. The exhaust gas from the Venturi cyclone separator II is fed to the Venturi dryer I of the first stage of thermal treatment through a gas conduit.

[0013] The heat required for calcination is generated by direct combustion of fuel (natural gas or fuel oil), which is supplied to the burners through the air distribution furnace floor.

[0014] The thorough mixing of gas and material promotes heat exchange and allows the calcination temperature in the furnace to be controlled. During normal operation, it is kept constant at about 1,100°C.

[0015] The internal circulation of solids in the upper part of the calciner in a fluidized bed expansion results in a continuous reduction in the solids concentration until a relatively low material concentration is reached. The dusty hot gases coming out of the calciner enter the circulation cyclone separator, where the material is separated from the gases. The exhaust gases enter the Venturi Dryer II, where they are mixed with the solids from the first stage of drying.

[0016] The hot material separated in the cyclone separator at a temperature of 950 to 1,100°C passes through a U-shaped fluidized bed damper and enters the fluidized bed of the calcining device again. In this way, the solid circulates in the calcining zone and has a uniform temperature of 1,000°C.

[0017] Part of the calcined material from the fluidized bed baffle is discharged into the gas pipe of the fluidized bed cooler through the discharger.

[0018] The gas duct of the fluidized bed cooler also receives hot air from the fluidized bed cooler. The material from the discharger and the hot air from the fluidized bed cooler enter the fluidized bed cooler cyclone for separation. The inlet of the fluidized bed cooling cyclone receives the exhaust gas from the discharge cyclone. The partially cooled material from the fluidized bed cooling cyclone enters the fluidized bed cooler. The heated exhaust gas is fed into the calciner as secondary air.

[0019] The cooling of the alumina in the fluidized bed cooler is caused by direct and indirect heat transfer. Direct heat exchange between the alumina and the air occurs in the six chambers of the fluidized bed cooler. The constant temperature of the fluidized bed is maintained in these chambers of the cooler by introducing the appropriate amount of air through the air distribution bottom plate.

[0020] Indirect heat exchange is achieved by passing air through an air heat exchanger located in a hot alumina bed.

[0021] The primary air preheated to 520°C in the air heat exchanger of the fluidized bed cooler is introduced into the calciner through an air distribution hood located at the bottom of the calciner tower.

[0022] In the last three sections of the fluidized bed cooler, the material is further cooled by water-cooled heat exchangers. Water circulates in a closed loop. The calcined product is fed to the final product barrel by a pneumatic silo pump.

[0023] Higher productivity of calciners and new requirements on alumina quality have led to changes in calciner design.

[0024] In the prior art, fluidized or suspended beds are used in all stages of the thermal treatment process, such as drying, dehydration and phase change. This results in high production capacity and energy efficiency of fixed circulating fluidized bed equipment, the ability to produce alumina with a wide range of physical and chemical properties, and many opportunities for automation.

[0025] However, heat treatment at high heat carrier velocities also results in high recirculation loads in such furnaces. High recirculation loads not only require additional heat to cyclically heat the material, but also increase the weight of the dust collection and heat exchange equipment. It also significantly increases the load on the electrostatic filter, resulting in higher irreversible material losses and air emissions.

[0026] The circulation path can be divided into several loops. The most obvious is the loop that includes fluidized bed cooler-fluidized bed cooler cyclone-calciner-circulating cyclone-Venturi II dryer-Venturi II cyclone-Venturi I dryer-dual zone electrostatic filter-Venturi II dryer (the "large" loop). The second apparent circulation loop is the small loop that includes fluidized bed cooler-fluidized bed cooler cyclone.

[0027] The prior art also includes solutions for intensifying heat exchange by adding a bypass (DE10331364B3, published on January 27, 2005). In addition to the original fluidized bed damper design that promotes intensified heat exchange between calcined alumina and bypassed aluminum hydroxide, a double-layer fluidized bed cooler design has been proposed. Each section of the fluidized bed cooler (FBC) is equipped with a separate cyclone separator, which not only improves heat recovery but also reduces the load of the FBC cyclone separator.

[0028] Prior art (DE10140261A1, published on February 27, 2003) proposes to feed the calcined alumina into a four-stage cross-flow heat exchanger with a suspended bed cyclone separator before feeding it into a fluidized bed cooler. The sequential application of four cyclone separators not only increases the heat recovery from the calcined alumina, but also slightly reduces the circulation of alumina particles due to better separation of dust and gas flow.

[0029] The above method aims at intensifying heat exchange, but it cannot effectively reduce the undesirable circulating load in the fluidized bed furnace. Using cyclone separators as heat exchangers and for gas-dust separation has significant disadvantages. Cyclone separators inherently have very low (less than 1%) removal efficiency of ultrafine (0.1 to 1.0 μm) particles. Note that the circulating load mainly consists of these ultrafine particles.

[0030] Due to the high temperatures at critical points in the circulation loop (about 400 to 600°C), the use of a fine gas cleaning system is not feasible. The widespread solution is to add additional zones to the electrostatic precipitator field. This requires a large investment. Furthermore, while this reduces non-recoverable losses of alumina and environmental emissions, it does not help to reduce excess recirculation loads or improve furnace performance.

[0031] The solution closest to the present invention is a process (WO9718165, published on May 22, 1997) in which partly dried aluminum hydroxide is sent to a heat treatment (so-called bypass) by the heat of calcining aluminum oxide. This is achieved as follows ( Figure 1 ). After the aluminum hydroxide raw material is preliminarily heat treated in the Venturi dryer I1, it is sent to the electrostatic precipitator 3 through the gas conduit 2. The captured material in the electrostatic precipitator 3 is collected by the screw feeder 4 and discharged into the airlift 5 in the pneumatic conveyor 6. From the airlift 6, the material enters the cyclone discharger 7 with the fluidized bed baffle 8. According to the prior art, most of the captured material is sent from the cyclone discharger 7 to the Venturi II dryer 10, and then enters the entire calcination cycle through the fluidized bed baffle 8 and the channel 9.

[0032] Another part of the material is sent through a chute 11 to the calcined alumina discharger 12 of the recirculation cyclone 13 and then to the cyclone 15 together with the calcined alumina and the dusty air from the fluidized bed cooler 14. The heat from the calcined alumina and the hot air from the fluidized bed cooler are used in the final stage of the thermal treatment of the alumina and are subsequently cooled in the fluidized bed cooler. In this way, a part of the material is removed from the total flow (bypass).

[0033] Although this solution allows a slight reduction in the specific fuel consumption, it does not reduce the load on the electrostatic precipitator and therefore the irreversible alumina losses. Furthermore, the amount of material fed through the bypass must be constantly monitored, since its increase will reduce the quality of the final product. Summary of the invention

[0034] The invention separates fine particles of alumina from the gas-dust stream and removes them from the process without reducing the capacity of the furnace. The technical effect of the invention is reduced calcined material losses, increased capacity and reduced fuel consumption rate.

[0035] The technical effect is achieved by providing a heat treatment device for aluminum hydroxide, which includes an electrostatic precipitator (1) having at least two compartments, a dust collecting hopper (3) for the second compartment of the electrostatic precipitator (1), a discharge hopper (7), a collecting hopper (35) for dust from the first compartment of the electrostatic precipitator having a pneumatic conveyor (36) and an air lift (37), a cyclone separator (54) for pre-cleaning, which is connected to a storage hopper (60), the storage hopper is connected to a screw feeder (68) and a fluidized bed cooler (26) through a baffle feeder (65) and a chute (67), and the fluidized bed cooler (26) is connected to a circulating cyclone separator (31) through an air duct (30), and the calcined material is discharged to the fluidized bed cooler via the circulating cyclone separator through a discharge device (32) attached to the lower part of the circulating cyclone separator (31). In the cyclone separator (33) of the fluidized bed cooler, there is a chute (34) in the lower part of the cyclone separator, which is capable of discharging the calcined material from the cyclone separator (33) of the fluidized bed cooler into the fluidized bed cooler (26), and the dust collection hopper (3) is connected to the discharge hopper (7) and the system of pneumatic cavity pumps (10, 13, 14) through the channel (4) to discharge the collected dust from the second zone of the electrostatic precipitator (1) into the final product barrel, wherein the device includes a cyclone separation discharger (38), the cyclone discharger has a system of gas pipes (39-45) equipped with valves (46-53), and the cyclone separation discharger is connected to the air lift (37) at its lower part and to the pre-cleaning cyclone separator (54) and the fine filter (55) at its upper part through the system of gas pipes (39-45).

[0036] According to alternative embodiments, the present invention may also include the following aspects:

[0037] A fan (80) having a baffle (81) is installed on the gas pipeline (45) of the device.

[0038] At least one of the dust hopper (3), the discharge hopper (7) and the storage hopper (60) comprises a flat vibrator (17, 18, 69) and a dehumidified air connection.

[0039] The fluidized bed cooler (26) may include an exhaust system on its cover to allow the system to be located above the alumina layer entering the fluidized bed cooler (26).

[0040] The fine filter (55) is connected to the storage hopper (60) and the discharge hopper (7) so that the captured dust is discharged to the fluidized bed cooler (26) or the air chamber pump system (10, 13, 14) and then discharged to the final product barrel.

[0041] The pre-cleaning cyclone (54) and fine filter (55) incorporate a bypass system for servicing and preventive maintenance of the unit. DETAILED DESCRIPTION

[0042] A mathematical model of the calcination process in a fixed fluidized bed furnace has been developed to solve the given problem.

[0043] The model has been used to analyze over sixty options for reducing undesirable recirculating loads by adding more dust collection devices at various points in the large and small recirculating loops.

[0044] The chosen approach to reducing the circulating load of fine particles must satisfy process constraints.

[0045] The high temperatures in the circulation loop (350 to 380°C) and the volume of the gas-dust mixture (approximately 200,000m 3 / h) prevents the integration of bag or cartridge filters in existing furnaces. Adding cyclones has no significant effect, since the efficiency of cyclones for fine particle removal is less than 1%. Analysis shows that adding cyclones reduces the specific fuel consumption by 0.5% and reduces dust emissions by 29.4%. The efficiency decreases even further with an increasing share of fine particles in the raw material.

[0046] The analysis also showed that the amount of material removed from the fluidized bed cooler has a small effect on the total dust load of the precipitator and the dust circulation within the large circuit. Even at the maximum discharge from the fluidized bed cooler of about 10 t / h, the dusty secondary air is cleaned in several stages in the "fluidized bed cooler cyclone - circulation cyclone - Venturi II cyclone" circuit. The multi-stage cleaning compensates for the initial high dust content of the air from the cooler, which means that the cooler material does not significantly affect the final discharge from the electrostatic precipitator, although additional heat is required.

[0047] A review of the prior art and an analysis based on mathematical models has allowed the following solutions to be proposed to reduce the cyclic loads.

[0048] The captured fine dust from the second zone of the electrostatic precipitator is redirected into the final product.

[0049] Reposition the air extraction point of the fluidized bed cooler. Instrumental measurements showed that due to the layer height and the overflow of the cooler, some alumina entered the piping from the fluidized bed cooler and entered the cooler cyclone inlet together with alumina from the recirculation cyclone discharge. The entry of alumina from the fluidized bed cooler increased the load on the suction cyclone and contributed to the increased circulation load within the small loop.

[0050] To reduce the circulating load of fine particles, the dust-air mixture from the discharge cyclone of the airlift is directed to an additional cleaning circuit consisting of a primary cyclone and a fine cleaning bag or cartridge filter.

[0051] Figure 2 The proposed apparatus and method for thermal treatment of powders are shown in FIG.

[0052] The device comprises an electrostatic precipitator 1 , an electrostatic precipitator screw feeder 2 and a dust collecting hopper 3 for collecting dust from the second zone of the electrostatic precipitator 1 , which is directly installed below the electrostatic precipitator screw feeder 2 .

[0053] The dust hopper 3 is connected to the discharge collection hopper 7 through a channel 4, which is equipped with a baffle 5 and a gate feeder 6. A chute 8 with a baffle 9 is installed at the lower part of the discharge hopper, which is connected to the pneumatic chamber pump No. 1 (PCP 1) 10 of the furnace.

[0054] The discharge hopper is connected to a pneumatic chamber pump (PCP 2) 13 through a pipe 11 on which a valve 12 is installed to transfer material from the discharge hopper 7 to the pneumatic chamber pump No. 2 (PCP 2) 13. The pneumatic chamber pump (PCP 2) 13 is connected to a pneumatic chamber pump No. 3 (PCP 3) 14 for backup.

[0055] Valves 15 and 16 are provided to switch the pneumatic chamber pumps PCP 1 (10), PCP 2 (13) and PCP 3 (14) to feed the material to the final product barrel via the pneumatic conveyor.

[0056] Agglomeration of fine dust can lead to clogging of the hopper and interruption of the dust flow through the pipeline. To prevent agglomeration, platform vibrators 17 and 18 are installed on the discharge hopper 3 and the collection hopper 7. In addition, for ventilation and prevention of agglomeration, dry compressed air is supplied to the hoppers 3 and 7 through pipes 19 and 20 with shut-off valves 21 and 22.

[0057] To release the air pressure, the collecting discharge hopper 7 is equipped with a release line 23 and a valve 24. The air is released through a nozzle 25 into the first zone of the electrostatic precipitator 1.

[0058] The claimed device further comprises a fluidized bed cooler (FBC) 26. Its cover comprises an outlet to extract secondary air from the fluidized bed cooler 26. This outlet is connected to the air duct 27 via plugs 28 and 29.

[0059] The fluidized bed cooler 26 is connected to a circulating cyclone 31 through an air duct 30, and the cyclone is arranged to send the calcined material into a cyclone 33 of the fluidized bed cooler through a discharge port 32 connected to the lower part of the circulating cyclone 31. A chute 34 is attached to the lower part of the cyclone to discharge the calcined material from the cyclone 33 of the fluidized bed cooler into the fluidized bed cooler 26.

[0060] The screw feeder 2 of the electrostatic precipitator 1 is equipped with a receiving hopper 35 for collecting dust from the first zone of the electrostatic precipitator 1. The receiving hopper 35 is connected through a pneumatic conveyor 36 to an air lift 37 which is connected to a cyclone discharger 38.

[0061] The cyclone discharger 38 is equipped with a gas duct system 39 - 45 with gates 46 - 53 and is connected through the gas duct system to a preliminary cleaning cyclone 54 and a fine filter 55 designed for final cleaning of the air coming from the cyclone 38 .

[0062] The fine filter 55 , which may be a bag or cartridge filter, is connected to a valve 57 thereon via a pipe 56 for regeneration of the bag / cartridge filter 55 and supply of dry compressed air.

[0063] The discharge cone 54 of the pre-cleaning cyclone is connected to a storage hopper 60 via a chute 58 having a baffle 59 .

[0064] Chutes 61 and 62 with gates 63 and 64 and baffle feeders 65 and 66 are mounted on the discharge cone of the storage hopper 60 .

[0065] The baffle feeder 65 is connected to the screw feeder 68 and the fluidized bed cooler 26 through a chute 67 .

[0066] In order to prevent agglomeration, a platform vibrator 69 is installed on the storage hopper 60, and a dehumidified air supply line 70 having a valve 71 is provided. The storage hopper 60 is also connected to a valve 73 and a nozzle 25 of the electrostatic precipitator 1 through an air release line 72.

[0067] The fine filter 55 is connected to the storage hopper 60 and the collecting hopper 7 through chutes 74, 75 having gates 76, 77 and baffle feeders 78, 79, respectively.

[0068] In order to compensate for the pressure loss in the pre-cleaning of the cyclone separator 54 and the fine filter 55 , a fan 80 having a baffle 81 is installed on the clean air discharge line 45 connecting the cyclone separator 54 to the filter 55 .

[0069] The device can be divided into three units.

[0070] 1. A unit that reduces circulating load by removing fine dust particles from electrostatic precipitators;

[0071] 2. A unit for reducing the circulation load by reducing the material removed from the fluidized bed cooler 26 with cooling air;

[0072] 3. A unit for additional cleaning of the dust-air mixture from the discharge cyclone 38;

[0073] The operation of the first unit is as follows.

[0074] The fine dust from the second zone of the electrostatic precipitator 1 is conveyed to the dust collecting hopper 3 by means of a screw 2. The dust from the second zone of the electrostatic precipitator is conveyed from the hopper 3 through a channel 4 equipped with a baffle 5 and a baffle feeder 6 to a collecting discharge hopper 7. From there, it moves along a chute 8 through another baffle 9 to the chamber pump (PCP1) 10 of the furnace.

[0075] Taking into account the intermittent operation of the chamber pump, it is proposed to convey the material from the collecting discharge hopper 7 to the PCP 213 and then to the final product distribution pipeline through the pipeline 11 equipped with a baffle 12. The gates 15 and 16 enable the discharge of the final product and fine dust from the second zone of the electrostatic precipitator 1 using the backup chamber pump PCP 3 (14).

[0076] As mentioned above, in order to prevent the highly dispersed dust from agglomerating, platform vibrators 17 and 18 are installed on the hopper 3 and the collecting discharge hopper 7. In addition, the supply of dehydrated aeration air is facilitated by pipes 19 and 20 with stop valves 21 and 22.

[0077] A pressure relief line 23 with a valve 24 is provided to release the charging air from the discharge hopper 7. The charging air is discharged through a nozzle 25 into the first zone of the electrostatic precipitator 1.

[0078] The second unit for reducing the circulating load by reducing the material removed from the fluidized bed cooler 26 with cooling air operates as follows.

[0079] The secondary air extracted from the end face has been relocated to the cover using the air duct 27. For switching to normal operation, plugs 28 and 29 are provided. When the plug 28 is closed, all the air from the fluidized bed cooler 26 travels through the gas duct 27 via the open plug 29. It enters the standard air duct 30 of the fluidized bed cooler 26 and combines with the annealed material from the circulating cyclone 31, which is discharged by the unloading device 32, and the air-dust mixture enters the cyclone 33 of the fluidized bed cooler, where the air flow is separated. The captured material is directed to the fluidized bed cooler 26 through the chute 34, while the clean air is supplied to the calciner for combustion according to the standard process.

[0080] If necessary, plug 28 is opened, plug 29 is closed, and the system operates in normal mode, drawing air through the end wall of the fluidized bed cooler 26.

[0081] The third unit provides additional cleaning of the dust-air mixture from the cyclone discharger 38 and operates as follows.

[0082] Before the operation starts, the damper 53 of the gas duct 41 is closed. The dust-air mixture from the cyclone 38 travels through the gas duct 39, the damper 46 and the damper 47 of the gas duct 40 before entering the pre-cleaning cyclone 54. After the pre-cleaning cyclone 54, the pre-cleaned dust-air mixture is directed to the bag / cartridge filter 55 via the gas duct 42 via the gates 48 and 50, where the air flow is finally cleaned of fine dust particles. After cleaning, the air passes through the damper 52 through the gas duct 45 and enters the inlet of the fan 80. The fan compensates for the pressure loss in the section between the cyclone 38 and the cyclone 33 of the fluidized bed cooler, which is increased due to the installation of the cyclone 38, the fine filter 55, the gate and the gas duct.

[0083] In order to be able to fine-tune the pressure / vacuum in the section between cyclone 38 and cyclone 33 of the fluidized bed cooler, a baffle 81 is provided.

[0084] A bypass system is also provided to facilitate preventive maintenance or repair of the cyclone 54 and the filter 55. If necessary, the damper 49 of the gas duct 43 is opened and the gates 47 and 48 are closed. This isolates the pre-cleaning cyclone 54 from the process. If the gates 46, 47, 48 and 51 are open and the gates 49, 50 and 52 are closed, the fine filter 55 is isolated from the process. The cyclone 38 dust cleaning circuit can also be completely isolated. For this purpose, the damper 53 of the gas duct 41 is opened and the damper 46 of the gas duct 40 is closed.

[0085] The dust captured in the pre-cleaning cyclone 54 is directed to a storage hopper 60 through a chute 58 with a baffle 59. There are two options for treating the dust from the pre-cleaning cyclone 54. In the first option, the dust is directed through a chute 61, a baffle 63 and a baffle feeder 65 to a screw feeder 68 through a chute 67 and then to the second chamber of the fluidized bed cooler 26. Passing the material through the baffle feeder 65 and the screw feeder 68 prevents it from being released from the pressurized fluidized bed cooler 26 into the storage hopper 60. Feeding the material to the second chamber of the fluidized bed cooler 26 allows thermal treatment to be performed and a specific quality of the final product to be obtained.

[0086] A second option for handling the dust from the storage hopper 60 consists in feeding the dust through a chute 62, a baffle and a baffle feeder 66 to a discharge hopper 7 and then to a final product hopper.

[0087] There are two further options for handling the dust from the fine filter 55. In the first option, the dust captured in the filter 55 is directed through the chute 74, baffle 76 and baffle feeder 78 to the hopper 60 and then to the fluidized bed cooler 26 as described above.

[0088] The second option involves directing the dust through a chute 75, a baffle 77 and a baffle feeder 79 to a discharge hopper 7 and then to a final product barrel.

[0089] To prevent clogging and caking during shutdown periods, the blowing air is delivered to long (more than 5 m) channels.

[0090] The proposed device for thermal treatment in a fixed fluidized bed furnace not only reduces the load on the electrostatic precipitator or other final exhaust gas cleaning units, thereby reducing the environmental footprint, but also reduces the irreversible losses of the calcined material by extracting fine and ultrafine particles of the calcined material. In addition, the reduction of additional circulating loads leads to higher productivity and reduced specific fuel consumption. Depending on the characteristics of the calcined material, emissions are reduced by 80 to 90%, specific fuel consumption is reduced by 1.5 to 2.2%, and productivity is increased by 10 to 15%.

Claims

1. An aluminum hydroxide heat treatment device, comprising an electrostatic precipitator (1) having at least two zones, a dust collecting hopper (3) for the second zone of the electrostatic precipitator (1), a discharge hopper (7), a receiving hopper (35) for dust from the first zone of the electrostatic precipitator having a pneumatic conveyor (36) and an air lift (37), a pre-cleaning cyclone separator (54) connected to the collecting hopper (60), which is connected to a screw feeder (68) and a fluidized bed cooler (26) via a baffle feeder (65) via a chute (67); the fluidized bed cooler (26) is connected to a circulating cyclone separator (31) via an air duct (30), and the calcined material is discharged to the cyclone of the fluidized bed cooler through the circulating cyclone separator via a discharger (32) attached to the bottom of the circulating cyclone separator (31). a cyclone unloader (38) having a gas pipeline system (39-45) with a gate (46-53) mounted thereon, the gate being connected at its bottom to an air lift (37) and at its top, above the gas pipeline system (39-45), to a pre-cleaning cyclone separator (54) and a fine filter (55).

2. The device according to claim 1, characterized in that A fan (80) having a baffle (81) is attached to the gas duct (45).

3. The device according to claim 1, characterized in that At least one of the dust hopper (3), the discharge hopper (7) and the dust hopper (60) comprises a platform vibrator (17, 18, 69) and a connection point for supplying dehumidified air.

4. The device according to claim 1, characterized in that The fluidized bed cooler (26) includes an air removal system on its cover that can be located above the alumina layer entering the fluidized bed cooler (26).

5. The device according to claim 1, characterized in that The fine cleaning filter (55) is connected to the collecting hopper (60) and the discharge hopper (7) so that the captured dust can be discharged to flow into the system of the fluidized bed cooler (26) or the pneumatic chamber pump (10, 13, 14), and then into the final product barrel.

6. The device according to claim 1, characterized in that Both the pre-cleaning cyclone separator (54) and the fine filter (55) are designed to be isolated from the process using a bypass system to facilitate repair and preventive maintenance of the device.

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