Aluminum fluoride and aluminum oxide mixing device for aluminum electrolytic cell and implementation method thereof

Abstract

The present invention discloses an aluminum fluoride and aluminum oxide mixing device for an aluminum electrolytic cell, comprising an aluminum fluoride feeding bin, a material storage bin, a PLC connected to the material storage bin, and other components. The present invention also discloses a method for implementing the aluminum fluoride and aluminum oxide mixing device for an aluminum electrolytic cell, comprising the steps of S10, calculating the single addition amount of aluminum fluoride based on the acquired parameter value; S11, calculating the single addition flow rate of aluminum fluoride based on the single addition amount of aluminum fluoride obtained in step S10, and the like. The present invention detects the flow of aluminum oxide in the alumina pneumatic chute through a flow detection device and conveying air pressure, so that the PLC can realize accurate automatic control of the feeding of aluminum fluoride, so that aluminum fluoride and aluminum oxide can be uniformly mixed and then added to the electrolytic cell simultaneously, thereby realizing continuous, uniform, and quantitative addition of aluminum fluoride.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrolytic aluminum production, and specifically relates to an aluminum fluoride and aluminum oxide mixing device for an aluminum electrolytic cell and a method for implementing the same. Background Art

[0002] In the current domestic electrolytic aluminum production process, aluminum fluoride is used as an additive, and its unloading generally adopts independently operated aluminum fluoride unloading equipment and a timed unloading method with a fixed unloading cycle. However, this independently operated aluminum fluoride unloading equipment unloads aluminum fluoride once every time the interval time is reached during operation, which will result in a relatively large amount of aluminum fluoride unloaded at the current time point. As time changes, the closer to the next unloading time point, the relatively less aluminum fluoride content, which increases the fluctuation of aluminum fluoride content during the electrolytic cell production process, and the electrolyte molecular ratio is unstable, which is not conducive to stable production and reduced power consumption. In addition, aluminum fluoride needs to be manually added to the aluminum fluoride bin of the aluminum fluoride unloading equipment. Due to the large number of electrolytic cells, the labor intensity is extremely high.

[0003] It can be seen from this that the existing aluminum fluoride feeding equipment is unable to achieve synchronous feeding of aluminum fluoride and aluminum oxide, resulting in increased fluctuations in the aluminum fluoride content during the electrolytic cell production process, causing instability in the electrolyte molecular ratio, and adversely affecting the stability of electrolytic aluminum production. Therefore, it is urgent to develop an aluminum fluoride and aluminum oxide mixing device that can continuously and evenly add aluminum fluoride to aluminum oxide in proportion to the aluminum fluoride consumption in the electrolytic cell and the aluminum oxide delivery flow rate, uniformly mix with the aluminum oxide, and then add it to the electrolytic cell synchronously with the aluminum oxide feeding, so as to achieve continuous and uniform addition of aluminum fluoride. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above-mentioned problems existing in the existing aluminum fluoride feeding equipment, and to provide an aluminum fluoride and alumina mixing device for aluminum electrolytic cells, which can continuously and evenly add aluminum fluoride to alumina in proportion according to the aluminum fluoride consumption of alumina and the alumina conveying flow rate, and after uniformly mixing with the alumina, it is fed into the electrolytic cell synchronously with the alumina, thereby achieving continuous and uniform addition of aluminum fluoride and alumina and a method for achieving the same.

[0005] The object of the present invention is achieved through the following technical scheme: an aluminum fluoride and alumina mixing device for an aluminum electrolytic cell, comprising a PLC, an aluminum fluoride feed bin, an electric ball valve arranged at the feeding port of the aluminum fluoride feed bin, a screw conveyor connected to the feed port of the aluminum fluoride feed bin, one or more weighing sensors arranged on a bracket of the aluminum fluoride feed bin, a flow detection device connected to the PLC for detecting the flow information of alumina in the feed trough of the alumina pneumatic chute, and a pressure transmitter for detecting the air pressure in the air duct of the alumina pneumatic chute; the screw conveyor and the weighing sensor are both connected to the PLC.

[0006] Furthermore, the mixing device also includes a material storage bin connected to the electric ball valve at the feeding port of the aluminum fluoride lower bin through a material conveying pipe, and a transmission motor arranged inside the material storage bin is connected to the PLC.

[0007] In order to achieve better use effect, the aluminum fluoride discharge silo consists of a circular silo and a conical silo connected to the circular silo; the cone head of the conical silo is provided with a discharge barrel; the feeding end of the screw conveyor is connected to the discharge barrel of the conical silo, and its discharge end is connected to the material trough of the alumina pneumatic chute.

[0008] A silo unloading stirring mechanism is also provided on the aluminum fluoride unloading silo, which includes a stirring motor vertically fixed at the center of the top cover of the aluminum fluoride unloading silo, a stirring shaft arranged inside the aluminum fluoride unloading silo and fixedly connected to the transmission shaft of the stirring motor, one or more stirring support shafts located inside the aluminum fluoride unloading silo and arranged on the stirring shaft, and a stirring transmission head arranged at the end of the stirring shaft; the stirring motor is connected to the PLC.

[0009] Furthermore, the stirring motor is a reduction motor with a reduction ratio of 1:50 to 1:300. The stirring shaft and stirring support shaft are both made of anti-magnetic stainless steel, and the lengths of the stirring support shafts decrease in sequence along the direction from the stirring motor to the stirring transmission head.

[0010] The screw conveyor is a screw discharging machine with a sealed pressure-maintaining function and anti-electromagnetic interference, and the motor of the screw conveyor is a variable frequency speed regulating motor with a rotation speed of 0.5 rpm to 100 rpm and a motor power of 0.5 kW to 3 kW.

[0011] The weighing sensor is a strain gauge bellows weighing sensor, and the flow detection device is a microwave solid powder flow detection device.

[0012] The pressure transmitter is installed at the end of the alumina pneumatic chute and is connected to the PLC through a signal line; the air pressure in the air duct of the alumina pneumatic chute is 0-7KPa, and the air pressure is proportional to the addition amount of alumina and aluminum fluoride.

[0013] In order to ensure the air pressure balance of the mixing device, an air pressure balance branch pipeline connected to the interior of the aluminum fluoride lower silo is also provided on the air duct of the alumina pneumatic chute.

[0014] The aluminum fluoride discharge bin, screw conveyor and flow detection device are all installed and fixed at the inlet end of the super-dense phase transportation of aluminum oxide in the electrolytic cell; the inlet end includes the outlet end of the screw conveyor and the pipeline for super-dense phase transportation to connect with the entire section of the branch pipeline of each electrolytic cell.

[0015] In order to facilitate the quick and convenient addition of materials to the same electrolytic cell, more than one alumina silo is provided below the alumina pneumatic chute, and the feed ports of these alumina silos are connected to the trough of the alumina pneumatic chute, and their discharge ports are connected to the same electrolytic cell.

[0016] The present invention also provides a method for implementing an aluminum fluoride and aluminum oxide mixing device for an aluminum electrolytic cell, comprising the following steps:

[0017] S10, calculating the single addition amount of aluminum fluoride according to the obtained parameter values;

[0018] S11, calculating the single addition flow rate of aluminum fluoride according to the single addition amount of aluminum fluoride obtained in step S10;

[0019] S12, the PLC determines whether there is alumina flowing in the alumina pneumatic chute. If yes, the process goes to step S13. If no, the PLC controls the stirring motor and the screw conveyor to stop in sequence.

[0020] S13, PLC controls the screw conveyor and stirring motor to start in sequence;

[0021] S14, PLC controls the speed of the screw conveyor to achieve quantitative mixing of aluminum fluoride and aluminum oxide.

[0022] Furthermore, the calculation formula for the single addition amount of aluminum fluoride in step S10 is: single addition amount of aluminum fluoride = total amount of aluminum fluoride added ÷ number of additions of aluminum fluoride, the total amount of aluminum fluoride added is (1-2%) of the total amount of aluminum oxide added, and the number of additions of aluminum fluoride is the same as the number of additions of aluminum oxide.

[0023] The calculation formula for the single addition flow rate of aluminum fluoride in step S11 is: single addition flow rate of aluminum fluoride = total amount of aluminum fluoride added ÷ number of aluminum fluoride additions ÷ single addition duration of aluminum fluoride × wind pressure coefficient, and the total amount of aluminum fluoride added, the number of aluminum fluoride additions and the single addition duration of aluminum fluoride are all pre-set as needed.

[0024] The method of the present invention also includes an aluminum fluoride feeding control method, which specifically includes the following steps:

[0025] S20. According to the total amount of aluminum oxide added to a single aluminum electrolytic cell per day, set the starting time and duration of aluminum fluoride addition to the single aluminum electrolytic cell per day, and enter the data into the PLC;

[0026] S21, PLC obtains the remaining amount of aluminum fluoride in the feed bin in real time, and controls the material storage bin to feed the aluminum fluoride feed bin;

[0027] S22, PLC determines whether the start time and duration have been reached, if yes, then executes step S23; if not, then returns to step S21;

[0028] S23, PLC controls the material storage bin and the electric ball valve to open in sequence, starts feeding and timing;

[0029] S24, PLC determines whether the aluminum fluoride feeding bin is completed; if not, return to step S23; if yes, PLC controls the material storage bin to stop feeding and close the electric ball valve in sequence, and the aluminum fluoride feeding is completed.

[0030] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0031] (1) The present invention sets a flow detection device for detecting the flow of alumina in the alumina pneumatic chute, and transmits the information to the PLC. The PLC controls the start and stop of the screw conveyor and the stirring motor according to the received information of the flow detection device, so that the aluminum fluoride in the aluminum fluoride lower hopper can be fully mixed with the alumina in the alumina pneumatic chute.

[0032] (2) The present invention can add aluminum fluoride to alumina in a continuous, uniform and quantitative manner in proportion based on the aluminum fluoride consumption of alumina and the alumina delivery flow rate, so that aluminum fluoride and alumina can be evenly mixed and then added to the electrolytic cell simultaneously, thereby achieving continuous, uniform and quantitative addition of aluminum fluoride, reducing the fluctuation of the aluminum fluoride content in the electrolyte, stabilizing the electrolyte molecular ratio in the electrolytic cell, and improving the electrolytic current efficiency.

[0033] (3) The present invention uses PLC to detect the weight of aluminum fluoride in the aluminum fluoride feed bin in real time based on the starting time and duration of aluminum fluoride addition, and the weighing sensor, so that the PLC can control the material storage bin to automatically refill the aluminum fluoride feed bin without manual intervention, thereby reducing the intensity of manual operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of the structure of a single device of the present invention.

[0035] Figure 2 This is a schematic diagram of the overall structure when multiple devices of the present invention are combined.

[0036] Figure 3 It is a structural schematic diagram of the silo unloading and stirring mechanism of the present invention.

[0037] Figure 4 This is a schematic diagram of the installation of the weighing sensor of the present invention.

[0038] Figure 5 It is a schematic diagram of the overall process structure of the present invention.

[0039] Figure 6 Schematic diagram of the structure of the aluminum fluoride feeding control method of the present invention.

[0040] The figure marks in the above drawings are: 1-aluminum fluoride discharge silo, 101-circular silo, 102-conical silo, 2-silo discharge stirring mechanism, 21-stirring motor, 22-stirring shaft, 23-stirring support shaft, 24-stirring support shaft rod, 25-stirring transmission head, 3-weighing sensor, 4-screw conveyor, 5-electric ball valve, 6-material storage silo, 7-alumina pneumatic chute, 8-flow detection device, 9-feeding pipe, 10-alumina silo, 11-pressure transmitter, 12-compression air duct. DETAILED DESCRIPTION

[0041] The present invention will be further described in detail below with reference to the examples, but the embodiments of the present invention are not limited thereto.

[0042] Example 1

[0043] Figure 1 Shown is a schematic diagram of the overall structure of a single mixing device of the present invention, Figure 2 This is a schematic diagram of the overall structure when multiple mixing devices are used in combination. Figure 1 As shown, the main structural components of the mixing device include PLC, aluminum fluoride discharge silo 1, silo discharge stirring mechanism 2, weighing sensor 3, screw conveyor 4, electric ball valve 5, material storage silo 6, alumina pneumatic chute 7, flow detection device 8 and pressure transmitter 11.

[0044] The material storage bin 6 is a conventional storage bin in the prior art with powder storage and conveying functions, and a transmission motor is provided inside the bin. Since it is a conventional technology, the structure of the material storage bin 6 is not described in detail in this specification.

[0045] The PLC is a conventional programmable control system in the prior art. It serves as the external control system of the present invention and is used to control the mixing of aluminum fluoride and aluminum oxide, thereby achieving automated unloading and refilling operations. The conveyor motor in the material storage bin 6 must be connected to the PLC to ensure that the PLC can control the conveyor motor's activation and deactivation.

[0046] The material mixing mechanism 2, screw conveyor 4, and load cell 3 are each connected to a PLC. In actual use, the PLC is connected to an external monitoring station and server via a communication bus. The monitoring station is responsible for monitoring the overall operation of the aluminum fluoride conveying system, including data display, historical records, and alarm information for each tank. It can also operate and process on-site equipment through the PLC. The server records various historical data and provides a basis for various data queries.

[0047] The aluminum fluoride feed silo 1 serves as a mixed feed silo for aluminum fluoride and alumina. The material storage bin 6 is connected to the electric ball valve 5 via a feed pipe 9, which is connected to the feed port of the aluminum fluoride feed silo 1 via a connecting hose. The electric ball valve 5 is connected to the feed port of the aluminum fluoride feed silo 1 via a connecting hose, which effectively reduces interference with the static and dynamic weighing results while preventing powder from escaping. The feed pipe 9 is connected to the feed end of the aluminum fluoride feed silo 1 via a connecting hose.

[0048] In some applications, the material storage bin 6 can also deliver aluminum fluoride via a pneumatic conveying chute to the aluminum fluoride discharge bin 1 located next to each electrolytic cell. However, in this embodiment, the preferred method of delivery is via a conveying pipe 9, i.e., a pipe chain-type conveying pipeline. A silo discharge and stirring mechanism 2 is disposed within the aluminum fluoride discharge bin 1. This mechanism primarily serves to stir the aluminum fluoride powder, allowing it to flow downward under gravity and simultaneously facilitates the discharge and delivery of the aluminum fluoride powder.

[0049] The feed end of the screw conveyor 4 is connected to the discharge barrel of the conical bin 102 of the aluminum fluoride discharge silo 1 via a flange, and its discharge end is connected to the alumina pneumatic chute 7, ensuring thorough mixing of the aluminum fluoride in the aluminum fluoride discharge silo 1 with the alumina flowing in the alumina pneumatic chute 7. To ensure optimal performance, the screw conveyor 4 in this embodiment preferably utilizes a dedicated screw discharger with airtight pressure-maintaining functions and electromagnetic interference protection. Sealing devices are installed at both ends of the screw conveyor's housing, both ends of the screw shaft, and at the internal joints to prevent the slightly positively pressurized powder from entering the bearings and leaking from the joints. To prevent electromagnetic interference during operation, the screw conveyor 4's housing, screw shaft, and end caps are constructed of electromagnetically resistant stainless steel. To accommodate varying conveying capacities, the screw conveyor 4's motor utilizes a variable-frequency speed-regulating motor with a speed range of 0.5 to 100 rpm and a power of 0.5 to 3 kW.

[0050] The alumina pneumatic chute 7 is a conventional structure, consisting of an air-permeable layer disposed within the chute, dividing the chute into two upper and lower layers. It also includes components such as a feed port, a discharge port, and an air inlet. The upper layer of the chute, commonly referred to as the feed chute, holds the alumina to be transported. The lower layer of the chute serves as a conduit for air flow, commonly referred to as the air duct. The feed port and discharge port are both connected to the feed chute, while an external compressed air duct 12 connects to the air duct of the alumina pneumatic chute 7 through the air inlet, providing wind power to the duct.

[0051] The weighing sensor 3 is a strain gauge bellows weighing sensor, and there are multiple weighing sensors. During installation, the weighing sensors 3 are evenly distributed on the bracket of the aluminum fluoride silo 1, and the weighing sensors 3 are located on the same horizontal plane. In this embodiment, the number of the weighing sensors 3 is preferably set to three. At the same time, in order to ensure accurate detection of the weight of aluminum fluoride in the aluminum fluoride silo 1, the three weighing sensors 3 mentioned above need to be evenly distributed on the circumference, that is, the angle formed between two adjacent weighing sensors 3 is 120°. The specific setting structure is as follows: Figure 4 shown.

[0052] The flow detection device 8 is used to detect the flow information of alumina in the alumina pneumatic chute 7. It must be connected to the PLC so that the detected and collected flow information of alumina can be transmitted to the PLC at any time. That is, this embodiment uses the flow detection device 8 to detect whether there is alumina flowing in the trough of the alumina pneumatic chute 7, so that the PLC can accurately control the start and stop of the silo unloading stirring mechanism 2 and the screw conveyor 4, so as to achieve the purpose of accurate mixing of aluminum fluoride and alumina.

[0053] In this embodiment, the flow detection device 8 is preferably implemented by a microwave solid powder flow detection device. During installation, the flow detection device 8 can be installed in the material trough of the alumina pneumatic chute 7 or in the air duct of the alumina pneumatic chute 7.

[0054] The pressure transmitter 11 is used to detect the wind speed in the air duct of the alumina pneumatic chute 7. It is installed at the chute end of the alumina pneumatic chute 7 and is connected to the PLC via a signal line. The pressure transmitter 11 and the flow detection device 8 together provide the PLC with corresponding information parameters.

[0055] During actual operation, the greater the wind pressure in the air duct of the alumina pneumatic chute 7, the greater the alumina delivery volume, and the correspondingly greater amount of aluminum fluoride added. Conversely, if the wind pressure in the air duct of the alumina pneumatic chute 7 is lower, the alumina delivery volume is lower, and the amount of aluminum fluoride added is correspondingly reduced. In other words, the wind pressure in the air duct of the alumina pneumatic chute 7 is directly proportional to the amount of alumina and aluminum fluoride added. Furthermore, different wind pressures result in different aluminum fluoride addition rates and flow rates. Therefore, in this embodiment, the wind pressure in the air duct of the alumina pneumatic chute 7 is preferably controlled between 0 and 7 kPa.

[0056] The structure of the aluminum fluoride lower bin 1 is as follows Figure 1As shown, the aluminum fluoride discharge silo 1 consists of a circular silo 101 and a conical silo 102. Specifically, a detachable silo cover is pre-installed on the top of the circular silo 101, a feed connection port is provided on the pre-installed silo cover, and an axial hole is provided in the center of the silo cover of the circular silo 101. The electric ball valve 5 is connected to the feed port of the circular silo 101 through a connecting hose. The conical silo 102 is connected to the circular silo 101. In actual production, the circular silo 101 and the conical silo 102 are connected by welding to form a volume of 0.05 to 0.2 m 3 The conical bin 102 has a cavity angle of 30 to 70 degrees. It is the discharge end bin, which ensures that aluminum fluoride is discharged without blockage during use. A discharge barrel is provided at the cone head of the conical bin 102, and the feed end of the screw conveyor 4 is connected to the discharge barrel of the conical bin 102 via a connecting hose.

[0057] The structure of the silo unloading and stirring mechanism 2 is as follows Figure 3 As shown, the silo unloading and stirring mechanism 2 includes a stirring motor 21, a stirring shaft 22, a stirring support shaft 23, a stirring support shaft rod 24, and a stirring transmission head 25, and the overall structure of the silo unloading and stirring mechanism 2 must match the internal structure of the circular silo 101 and the conical silo 102.

[0058] Among them, the stirring motor 21 is vertically fixed to the center of the top cover of the aluminum fluoride lower silo 1 by screws, and the transmission shaft of the stirring motor 21 extends into the aluminum fluoride lower silo 1 and can rotate freely. At the same time, the control end of the stirring motor 21 is connected to the PLC. In this embodiment, the stirring motor 21 is preferably implemented by a reduction motor with a large reduction ratio, and its reduction ratio is preferably 1:50 to 1:300. The stirring shaft 22 is located in the aluminum fluoride lower silo 1 and is fixedly connected to the transmission shaft of the stirring motor 21. The length of the stirring shaft 22 is the sum of the heights of the circular bin 101 and the conical bin 102.

[0059] The stirring transmission head 25 is fixedly connected to the end of the stirring shaft 22, and the central axis of the stirring transmission head 25 is on the same axis as the central axis of the stirring shaft 22. The stirring support shaft 23 and the stirring support shaft rod 24 are fixedly connected to form a whole, which is used to stir the material.

[0060] When connected, one end of the stirring support shaft 23 is vertically fixed to the stirring shaft 22, while the other end is fixedly connected to one end of the stirring support shaft rod 24. The distal end of the stirring support shaft rod 24 is arranged toward the stirring transmission head 25 and toward the stirring shaft 22. That is, through this structure, the stirring support shaft rod 24 and the stirring support shaft 23 form an angle of less than or equal to 90 degrees.

[0061] There are at least one stirring shaft 23, and the stirring shaft 22, stirring shaft 23, and stirring shaft rod 24 are all made of anti-magnetic stainless steel. To match the internal structure of the circular chamber 101 and the conical chamber 102, the length of the stirring shafts 23 decreases in sequence along the direction from the stirring motor 21 to the stirring transmission head 25.

[0062] In order to ensure the overall operation effect of the present invention, the aluminum fluoride discharge bin 1, the discharge stirring mechanism 2, the electric ball valve 5, the screw conveyor 4, the weighing sensor 3, the flow detection device 8 and the pressure transmitter 11 are all installed and fixed at the inlet end position of the super-dense phase transportation of aluminum oxide in the electrolytic cell. Moreover, the discharge port of the screw conveyor 4 and the flow detection device 8 are connected to the chute through a special device at the inlet part of the alumina pneumatic chute 7 on the top of each electrolytic cell. Among them, it is important to clarify that the inlet end of the super-dense phase transportation of aluminum oxide in the electrolytic cell includes the outlet end of the screw conveyor 4 and the pipeline for super-dense phase transportation to connect to the entire section of the branch pipeline of each electrolytic cell.

[0063] In specific implementation, the flow detection device 8 is used to detect the flow of alumina in the alumina pneumatic chute 7, and the pressure transmitter 11 is used to detect the wind speed in the air duct of the alumina pneumatic chute 7. The flow detection device 8 and the pressure transmitter 11 both transmit the collected information to the PLC. The PLC controls the start and stop of the screw conveyor 4 and the stirring motor 21 based on the received information, so that the aluminum fluoride in the aluminum fluoride discharge silo 1 can be fully mixed with the aluminum oxide in the alumina pneumatic chute 7. During the aluminum fluoride discharge process, the speed of the screw conveyor 4 should be greater than the speed of the stirring motor 21, that is, the discharge speed of the screw conveyor 4 should be greater than the discharge speed from the discharge silo, to ensure that no alumina accumulates between the aluminum fluoride discharge silo 1 and the screw conveyor 4.

[0064] Example 2

[0065] This embodiment provides a method for implementing an aluminum fluoride and aluminum oxide mixing device for an aluminum electrolytic cell based on embodiment 1, and its flow diagram is as follows: Figure 5 As shown, the specific steps include:

[0066] S10. Calculate the single addition amount of aluminum fluoride according to the obtained parameter values.

[0067] The formula for calculating the single addition amount of aluminum fluoride in this step is: Single addition amount of aluminum fluoride = Total amount of aluminum fluoride added ÷ Number of aluminum fluoride additions. Here, the total amount of aluminum fluoride added is (1-2%) of the total amount of aluminum oxide added, and the number of aluminum fluoride additions is the same as the number of aluminum oxide additions. The total amount of aluminum oxide added, the number of aluminum oxide additions, and the duration of each aluminum oxide addition are all pre-set as needed.

[0068] S11. Calculate the single addition flow rate of aluminum fluoride according to the single addition amount of aluminum fluoride obtained in step S10.

[0069] In this step, the single-addition flow rate of aluminum fluoride (unit: kg / minute) is calculated using the following formula: Single-addition flow rate of aluminum fluoride = total amount of aluminum fluoride added / number of aluminum fluoride additions / duration of single aluminum fluoride addition × wind pressure coefficient. This calculation provides the relevant numerical value for the single-addition flow rate of aluminum fluoride.

[0070] S12, PLC determines whether there is alumina flowing in the alumina pneumatic chute. If yes, execute step S13. If not, PLC controls the stirring motor and screw conveyor to stop in sequence.

[0071] S13, PLC controls the screw conveyor and stirring motor to start in sequence.

[0072] S14. The PLC controls the speed of the screw conveyor to achieve quantitative mixing of aluminum fluoride and aluminum oxide. Specifically, the PLC controls the speed of the screw conveyor based on the acquired aluminum fluoride weight information, the single addition amount of aluminum fluoride, the single addition duration of aluminum fluoride, and the single addition flow rate of aluminum fluoride, to achieve quantitative mixing of aluminum fluoride and aluminum oxide after integrating the above data.

[0073] The above method mainly involves a method for controlling the discharge of aluminum fluoride. During the execution of this method, an aluminum fluoride replenishment control method is also included. This aluminum fluoride replenishment control method is carried out simultaneously with the aluminum fluoride discharge control method, and the remaining aluminum fluoride is replenished at any time according to the remaining amount in the aluminum fluoride discharge bin.

[0074] The process of the aluminum fluoride feeding control method is as follows Figure 6 As shown, the specific steps include:

[0075] S20. According to the total amount of aluminum oxide added to a single aluminum electrolytic cell per day, the starting time and duration of aluminum fluoride addition to the single aluminum electrolytic cell per day are set and entered into the PLC.

[0076] S21, PLC obtains the remaining amount of aluminum fluoride in the feed bin in real time, and controls the material storage bin to feed the aluminum fluoride to the feed bin.

[0077] S22. The PLC determines whether the start time and duration have been reached. If yes, the process goes to step S23; if not, the process returns to step S21.

[0078] S23, PLC controls the material storage bin and the electric ball valve to open in sequence, starts feeding and timing.

[0079] S24, PLC determines whether the aluminum fluoride feeding bin is completed; if not, return to step S23; if yes, PLC controls the material storage bin to stop feeding and close the electric ball valve in sequence, and the aluminum fluoride feeding is completed.

[0080] Specifically, the PLC controls the start and stop of the conveyor in the material storage bin 6 based on the start and duration of aluminum fluoride addition, as well as the weight of aluminum fluoride in the aluminum fluoride hopper 1, as measured by the load cell 3. This ensures a quantitative replenishment of the aluminum fluoride into the hopper 1. This enables automatic filling of the aluminum fluoride, ensuring accurate replenishment without requiring manual intervention, effectively reducing labor costs.

[0081] As described above, the present invention can be well implemented.

Claims

1. A device for mixing aluminum fluoride and aluminum oxide for aluminum electrolytic cells, characterized in that: The invention comprises a PLC, an aluminum fluoride feed bin (1), an electric ball valve (5) arranged at a feeding port of the aluminum fluoride feed bin (1), a screw conveyor (4) connected to the feed port of the aluminum fluoride feed bin (1), one or more weighing sensors (3) arranged on a bracket of the aluminum fluoride feed bin (1), a flow detection device (8) connected to the PLC for detecting the flow information of aluminum oxide in the feed trough of the aluminum oxide pneumatic chute (7), and a pressure transmitter (10) for detecting the air pressure in the air duct of the aluminum oxide pneumatic chute (7). 11) and a material storage bin (6) connected to the electric ball valve (5) at the feeding port of the aluminum fluoride feeding bin (1) through a feeding pipe (9), a transmission motor provided inside the material storage bin (6) is connected to a PLC, the screw conveyor (4) and the weighing sensor (3) are both connected to the PLC, and an air pressure balance branch line connected to the interior of the bin body of the aluminum fluoride feeding bin (1) is also provided on the air duct of the alumina pneumatic chute (7); the PLC adjusts the pressure according to the starting time and duration of aluminum fluoride addition and the weighing sensor. The weight information of aluminum fluoride in the aluminum fluoride feeding bin (1) is collected by the device (3), and the start and stop of the conveyor of the material storage bin (6) are controlled to quantitatively replenish the aluminum fluoride feeding bin (1); a bin feeding stirring mechanism (2) is also provided on the aluminum fluoride feeding bin (1), and the bin feeding stirring mechanism (2) includes a stirring motor (21) vertically fixed at the center of the top cover of the aluminum fluoride feeding bin (1), and a stirring shaft (22) arranged inside the aluminum fluoride feeding bin (1) and fixedly connected to the transmission shaft of the stirring motor (21). , located inside the aluminum fluoride lower silo (1) and arranged on the stirring shaft (22), there are more than one stirring support shafts (23), and a stirring transmission head (25) arranged at the end of the stirring shaft (22); the stirring motor (21) is connected to the PLC; the screw conveyor (4) is a screw discharger with a sealed pressure-maintaining function and anti-electromagnetic interference, and the motor of the screw conveyor (4) is a variable frequency speed regulating motor with a rotation speed of 0.5 rpm to 100 rpm and a motor power of 0.5 kW to 3 kW.

2. The device for mixing aluminum fluoride and aluminum oxide for aluminum electrolytic cells according to claim 1, characterized in that: The aluminum fluoride discharge bin (1) is composed of a circular bin (101) and a conical bin (102) connected to the circular bin (101); the cone head of the conical bin (102) is provided with a discharge barrel; the feed end of the screw conveyor (4) is connected to the discharge barrel of the conical bin (102), and the discharge end is connected to the feed trough of the alumina pneumatic chute (7).

3. The device for mixing aluminum fluoride and aluminum oxide for aluminum electrolytic cells according to claim 2, characterized in that: The stirring motor (21) is a reduction motor with a reduction ratio of 1:50 to 1:

300.

4. The device for mixing aluminum fluoride and aluminum oxide for aluminum electrolytic cells according to claim 3, characterized in that: The stirring shaft (22) and the stirring support shaft (23) are both made of anti-magnetic stainless steel material, and the length of the stirring support shaft (23) decreases in sequence along the direction from the stirring motor (21) to the stirring transmission head (25).

5. The device for mixing aluminum fluoride and aluminum oxide for aluminum electrolytic cells according to claim 4, characterized in that: The weighing sensor (3) is a strain-type bellows weighing sensor, and the flow detection device (8) is a microwave solid powder flow detection device.

6. The device for mixing aluminum fluoride and aluminum oxide for aluminum electrolysis cells according to claim 5, characterized in that: The pressure transmitter (11) is installed at the end of the alumina pneumatic chute (7) and is connected to the PLC via a signal line; the air pressure in the air duct of the alumina pneumatic chute (7) is 0 to 7 kPa, and the air pressure is proportional to the amount of alumina and aluminum fluoride added.

7. The device for mixing aluminum fluoride and aluminum oxide for aluminum electrolytic cells according to claim 6, characterized in that: The aluminum fluoride feed bin (1), the screw conveyor (4) and the flow detection device (8) are all installed and fixed at the inlet end of the super-dense phase conveying of aluminum oxide in the electrolytic cell; the inlet end includes the outlet end of the screw conveyor (4) and the pipeline for super-dense phase conveying to connect with the entire section of the branch pipeline of each electrolytic cell.

8. The device for mixing aluminum fluoride and aluminum oxide for aluminum electrolytic cells according to claim 7, characterized in that: More than one alumina silo (10) is provided below the alumina pneumatic chute (7), and the feed ports of the alumina silos (10) are all connected to the trough of the alumina pneumatic chute (7).

9. The method for implementing the device for mixing aluminum fluoride and aluminum oxide for aluminum electrolytic cells according to any one of claims 1 to 8, characterized in that: The following steps are involved: S10, calculating the single addition amount of aluminum fluoride according to the obtained parameter values; S11, calculating the single addition flow rate of aluminum fluoride according to the single addition amount of aluminum fluoride obtained in step S10; S12, the PLC determines whether there is alumina flowing in the alumina pneumatic chute. If yes, the process goes to step S13. If no, the PLC controls the stirring motor and the screw conveyor to stop in sequence. S13, PLC controls the screw conveyor and stirring motor to start in sequence; S14, PLC controls the speed of the screw conveyor to achieve quantitative mixing of aluminum fluoride and aluminum oxide.

10. The method for implementing an aluminum fluoride and aluminum oxide mixing device for an aluminum electrolytic cell according to claim 9, wherein the calculation formula for the single addition amount of aluminum fluoride in step S10 is: single addition amount of aluminum fluoride = total addition amount of aluminum fluoride ÷ number of additions of aluminum fluoride, the total addition amount of aluminum fluoride is (1-2%) of the total addition amount of aluminum oxide, and the number of additions of aluminum fluoride is the same as the number of additions of aluminum oxide.

11. The method for implementing an aluminum fluoride and alumina mixing device for an aluminum electrolytic cell according to claim 10, wherein the calculation formula for the single addition flow rate of aluminum fluoride in step S11 is: single addition flow rate of aluminum fluoride = total amount of aluminum fluoride added ÷ number of aluminum fluoride additions ÷ single addition duration of aluminum fluoride × wind pressure coefficient.

12. A method for implementing an aluminum fluoride and aluminum oxide mixing device for an aluminum electrolytic cell according to claim 10 or 11, wherein the total amount of aluminum fluoride added, the number of aluminum fluoride additions, and the duration of a single aluminum fluoride addition are all pre-set as needed.

13. The method for implementing the device for mixing aluminum fluoride and aluminum oxide for aluminum electrolytic cells according to claim 12, characterized in that: The method also includes an aluminum fluoride feeding control method, which specifically includes the following steps: S20. According to the total amount of aluminum oxide added to a single aluminum electrolytic cell per day, set the starting time and duration of aluminum fluoride addition to the single aluminum electrolytic cell per day, and enter the data into the PLC; S21, PLC obtains the remaining amount of aluminum fluoride in the feed bin in real time, and controls the material storage bin to feed the aluminum fluoride feed bin; S22, PLC determines whether the start time and duration have been reached, if yes, then executes step S23; if not, then returns to step S21; S23, PLC controls the material storage bin and the electric ball valve to open in sequence, starts feeding and timing; S24, PLC determines whether the aluminum fluoride feeding bin is finished; if not, returns to step S23; If yes, the PLC will control the material storage bin to stop feeding and close the electric ball valve in sequence, and the aluminum fluoride feeding is completed.

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