Automatic periodic sampling system and sampling method for bulk aluminum oxide

Abstract

The invention provides an aluminum oxide bulk automatic periodic sampling system and a sampling method. The system comprises a silo used for storing aluminum oxide powder, a discharging pipe is arranged at the bottom of the silo, and two branch material pipes are arranged below the discharging pipe and are respectively a discharging branch pipe and a sampling branch pipe; a discharge valve is arranged between the discharge pipe and the inlet of the discharge branch pipe; a sampling valve is arranged between the outlet of the sampling branch pipe and the inlet of the discharging branch pipe; and the emptying valve and the sampling valve are electrically connected with the controller respectively. According to the system provided by the invention, the purpose of automatic sampling is achieved, so that the labor intensity of workers is reduced; and meanwhile, the problems of low working efficiency, dust damage to workers and the like caused by manual sampling are avoided. According to the method provided by the invention, the quality of the aluminum oxide powder loaded on the transport vehicle can be accurately controlled, and the sample can be effectively and reasonably collected, so that the sample collection efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of alumina sampling, and in particular to an automatic periodic sampling system and a sampling method for bulk alumina. Background Art

[0002] Alumina, the raw material of aluminum smelters, is an important industrial raw material. The quality and performance testing of it is of great significance to ensure product quality, improve production efficiency and ensure safety. Therefore, it is very necessary to sample and screen alumina samples when producing aluminum-related products.

[0003] At present, the sampling of alumina in bulk is still done manually. However, this method not only reduces the efficiency of workers in daily operations, but also creates a lot of dust on site during the manual sampling process, which can easily cause dust damage. With the increasing use of various instruments in the field of industrial automation, it is particularly necessary to develop a system that can automatically sample alumina in bulk. Summary of the invention

[0004] The purpose of the present invention is to solve the defects of the above-mentioned prior art and provide an automatic periodic sampling system and sampling method for bulk alumina.

[0005] An automatic periodic sampling system for bulk alumina includes: a silo for storing alumina powder, a discharge pipe is arranged at the bottom of the silo, and two branch pipes are opened below the discharge pipe, namely a discharge branch pipe and a sampling branch pipe;

[0006] A discharge valve is provided between the discharge pipe and the inlet of the discharge branch pipe;

[0007] A sampling valve is provided between the outlet of the sampling branch pipe and the inlet of the discharge branch pipe;

[0008] The discharge valve and the sampling valve are electrically connected to the controller respectively.

[0009] Furthermore, in the above-mentioned automatic periodic sampling system for bulk alumina, a flow switch for determining the sample flow rate is provided on the sampling branch pipe, and the flow switch is electrically connected to the controller.

[0010] Further, in the above-mentioned alumina bulk automatic periodic sampling system, the material flow switch comprises:

[0011] A sampling branch tube; a connecting rod is sealed and movably connected to the tube wall of the sampling branch tube, a detection spoon is fixed at one end of the connecting rod, and a connecting block is fixed at the other end; the detection spoon is inside the sampling branch tube; the connecting block is outside the sampling branch tube;

[0012] A housing, wherein the connection block is arranged above the housing;

[0013] A spring, one end of which is fixedly connected to the bottom of the housing, and the other end of which passes through the housing and has a moving contact fixed at its end;

[0014] An upper static contact and a lower static contact are fixed to the top and the bottom of the shell, respectively; under the tension of the spring, the moving contact can contact or disconnect with the upper static contact or the lower static contact to trigger a signal and transmit it to the controller.

[0015] Furthermore, in the above-mentioned alumina bulk automatic periodic sampling system, the angle between the connecting rod and the horizontal plane is: 0°≤angle≤75°.

[0016] Further, in the above-mentioned alumina bulk automatic periodic sampling system, the upper static contact is provided with two upper contacts; the static contact is provided with two lower contacts;

[0017] The movable contact is an H-shaped structure, and two contacts matching the position of the upper contact are arranged on the upper part of the movable contact; and two contacts matching the position of the lower contact are arranged on the lower part of the movable contact.

[0018] Furthermore, in the above-mentioned alumina bulk automatic periodic sampling system, a spring sleeve is sleeved on the outside of the spring, and the spring sleeve penetrates and is fixed on the upper shell wall of the shell.

[0019] Furthermore, in the above-mentioned alumina bulk automatic periodic sampling system, a feed pipe is provided below the silo, and a feed valve is provided on the feed pipe; a blower is provided at the inlet of the feed pipe; and a sensor capable of sensing a transport vehicle is provided at the outlet of the discharge branch pipe;

[0020] The sensor capable of sensing the transport vehicle, the feed valve, and the blower are all electrically connected to the controller.

[0021] Furthermore, in the above-mentioned automatic periodic sampling system for bulk alumina, a conveying device for conveying the alumina sample is provided below the outlet of the sampling branch pipe.

[0022] Furthermore, in the above-mentioned alumina bulk automatic periodic sampling system, the bottom of the silo is a conical structure, and an electric vibrator is provided on the outside of the side wall of the conical structure of the silo, and the electric vibrator is electrically connected to the controller.

[0023] A sampling method based on an automatic periodic sampling system for bulk alumina comprises the following steps:

[0024] (1) Turn on the blower and the feed valve through the controller to blow the alumina powder into the silo until the amount of alumina powder meets the requirement, and then turn off the blower and the feed valve;

[0025] (2) Determine whether there is a transport vehicle below the discharge branch pipe. If there is a transport vehicle, determine the total amount of alumina powder to be transported, and determine the opening time of the discharge valve and the sampling valve according to the total amount of alumina powder to be transported; the sampling valve is opened several times; each time is 5 minutes apart, and the initial single opening time is 5 minutes;

[0026] (3) Turn on the electric vibrator, and at the same time open the discharge valve and the sampling valve, so that the alumina powder in the silo falls into the discharge branch pipe and the sampling branch pipe respectively through the discharge pipe; the alumina powder falling from the sampling branch pipe is collected by the sampling collection mechanism;

[0027] (4) Turn on the material flow switch and determine the material flow state of the magnesium oxide powder falling into the sampling branch pipe through the material flow switch; when the material flow switch detects that no magnesium oxide powder has fallen into the sampling branch pipe, immediately close the discharge valve and the sampling valve for maintenance until magnesium oxide powder falls into the sampling branch pipe; when the material flow switch detects that a small amount of magnesium oxide powder has fallen into the sampling branch pipe, adjust the single opening time of the sampling valve according to the current magnesium oxide powder material flow rate;

[0028] (5) When the first sampling time of the sampling valve ends, close the sampling valve and the material flow switch until the second sampling time of the sampling valve begins, and then open the sampling valve and the material flow switch again;

[0029] (6) Repeat the opening and closing of the sampling valve and the material flow switch until the cargo load of the transport vehicle reaches the requirement, and then turn off the electric vibrator, discharge valve, material flow switch and sampling valve.

[0030] Beneficial effects:

[0031] The automatic periodic sampling system for bulk alumina provided by the present invention achieves the purpose of automatic sampling by arranging a sampling branch pipe on the discharge pipe and arranging a sampling valve on the sampling branch pipe whose opening and closing can be controlled by a controller, thereby reducing the labor intensity of workers; and at the same time avoiding the problems of low work efficiency and dust damage to workers caused by manual sampling.

[0032] The sampling method provided by the present invention, on the one hand, can more accurately control the quality of alumina powder loaded on a transport vehicle by controlling the sampling valve to take samples multiple times; on the other hand, the material flow rate of the sampling is monitored by the material flow switch, so that samples can be collected effectively and reasonably, ultimately improving the efficiency of sample collection. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the structure of the automatic periodic sampling system for bulk alumina of the present invention;

[0034] Figure 2 A schematic diagram of the material flow switch structure provided by the present invention;

[0035] Reference numerals:

[0036] 1-silo, 2-controller, 3-blower; 4-feeding valve; 5-electric vibrator; 6-discharging valve, 7-discharging pipe; 71-discharging branch pipe; 72-sampling branch pipe; 8-material flow switch; 9-sampling valve; 10-conveying device;

[0037] 801-detection spoon; 802-connecting rod; 803-connecting block; 804-spring; 805-upper static contact; 8501-upper contact; 806-moving contact; 807-lower static contact; 808-spring sleeve; 809-housing. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention is described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] The current manual sampling method of aluminum oxide powder reduces the efficiency of workers' daily work and increases the labor intensity of workers. In addition, due to the large amount of dust on site during the current daily manual sampling process, it is very easy to cause dust damage and also brings the possibility of vehicle damage. Therefore, the present invention provides a system that can automatically periodically sample. Figure 1 The schematic diagram of the structure of the automatic periodic sampling system for bulk alumina of the present invention is as follows: Figure 1 As shown, the system includes: a silo 1 for storing alumina powder, a discharge pipe 7 is arranged at the bottom of the silo 1, and two branch pipes are opened below the discharge pipe 7, namely a discharge branch pipe 71 and a sampling branch pipe 72; a discharge valve 6 is arranged between the discharge pipe 7 and the inlet of the discharge branch pipe 71; a sampling valve 9 is arranged between the outlet of the sampling branch pipe 72 and the inlet of the discharge branch pipe 71; the discharge valve 6 and the sampling valve 9 are electrically connected to the controller 2 respectively.

[0040] The system provided by the present invention controls the opening and closing of the discharge valve 6 and the sampling valve 9 through the controller 2. When the discharge valve 6 and the sampling valve 9 are both in the open state, the alumina powder in the silo 1 passes through the discharge pipe 7 and falls into the discharge branch pipe 71 and the sampling branch pipe 72 respectively, wherein the alumina powder falling into the discharge branch pipe 71 is transported to the destination by a transport vehicle, and the alumina powder falling into the sampling branch pipe 72 is tested as a sample to monitor the quality of the alumina powder transported this time.

[0041] The system provided by the present invention achieves the purpose of automatic sampling by arranging a sampling branch pipe 72 on the discharge pipe 7, and arranging a sampling valve 9 on the sampling branch pipe 72, the opening and closing of which can be controlled by the controller 2, thereby reducing the labor intensity of workers; at the same time, it avoids the problems of low work efficiency and dust damage to workers caused by manual sampling.

[0042] Furthermore, in the present invention, a material flow switch 8 for determining the sample flow rate is disposed on the sampling branch pipe 72 , and the material flow switch 8 is electrically connected to the controller 2 .

[0043] Specifically, the material flow switch 8 is used to determine the sample flow rate, and it can output three material flow signals, namely: a no material flow signal that does not hit the material flow switch, a small material flow signal, and a large material flow signal. The controller 2 determines the opening time of the sampling valve 9 according to the three material flow signals to ensure that the quality of the aluminum oxide powder sample obtained is sufficient for detection or other purposes.

[0044] The system provided by the present invention, by arranging a material flow switch 8 on the sampling branch pipe 72, enables the system to determine the opening time of the sampling valve 9 according to the material flow of the sample, thereby more accurately controlling the sampling amount of the aluminum oxide powder sample.

[0045] Further, Figure 2 The schematic diagram of the material flow switch structure provided by the present invention is as follows: Figure 2 As shown, the material flow switch 8 includes: a sampling branch tube 72; a connecting rod 802 is sealed and movably connected on the tube wall of the sampling branch tube 72, one end of the connecting rod 802 is fixed with a detection spoon 801, and the other end is fixed with a connecting block 803; the detection spoon 801 is inside the sampling branch tube 72; the connecting block 803 is outside the sampling branch tube 72; a shell 809, and the connecting block 803 is arranged above the shell 809; a spring 804, one end of the spring 804 is fixedly connected to the bottom of the shell 809, and the other end passes through the shell 809, and a moving contact 806 is fixed at its end; an upper static contact 805 and a lower static contact 807 are fixed at the top and bottom of the shell 809 respectively; under the tension of the spring 804, the moving contact 806 can contact or disconnect with the upper static contact 805 or the lower static contact 807 to trigger a signal and transmit it to the controller 2.

[0046] Specifically, after the connecting rod 802 passes through the tube wall of the sampling branch tube 72, one end of the connecting rod 802 is fixedly connected to the detection spoon 801, and the other end is fixed to the connecting block 803. The sealing connection between the connecting rod 802 and the sampling branch tube 72 can be: a hole that is adapted to the outer edge size of the connecting rod 802 is opened on the tube wall of the sampling branch tube 72, and a rubber sleeve is sealed and connected to the edge of the hole, and the other end of the rubber sleeve is sealed and connected to the connecting rod 802, so as to achieve a sealed and movable connection between the connecting rod 802 and the sampling branch tube 72.

[0047] In the initial state, the moving contact 806 is in contact with the lower static contact 807 (the two can be in contact with each other by magnetic adsorption). At this time, the lower static contact 807 triggers a material flow signal and transmits it to the controller 2, so that the controller knows that no sample has fallen in the current state; when a small amount of alumina powder falls, the alumina powder falls into the detection spoon 801, and due to the effect of its gravity, the connecting rod 802 begins to tilt, and the connecting block 803 moves upward, thereby driving the spring 804 to stretch, and the spring 804 stretches, thereby driving the moving contact 806 to move upward. , so that the lower static contact 807 is separated from the moving contact 806 (not in contact with the upper static contact 805 at this time), and the lower static contact 807 will trigger a separation signal to the controller 2, so that the controller knows that a small amount of sample has fallen in the current state; when a large flow of aluminum oxide powder falls, the detection spoon 801 moves further downward due to the effect of gravity, thereby driving the moving contact 806 to move further upward and contact with the upper static contact 805, and the upper static contact 805 will trigger a material flow signal and transmit it to the controller 2, so that the controller knows that a large flow of sample has fallen in the current state. Therefore, the controller 2 can determine the opening time of the sampling valve 9 according to the size of the aluminum oxide powder flow.

[0048] It should be noted that sensors capable of sensing the contact state (contact or separation) with the moving contact 806 are respectively provided on the upper static contact 805 and the lower static contact 807 , and the sensors can transmit the sensed material flow signals to the controller 2 .

[0049] The system provided by the present invention arranges the upper static contact 805, the moving contact 806, and the lower static contact 807 in the housing 809 so that the acquisition of the material flow signal is not affected by the outside world, thereby improving the contact sensitivity of the material flow switch and, on the other hand, also improving the service life of the material flow switch.

[0050] Furthermore, the angle between the connecting rod 802 and the horizontal plane is: 0°≤angle≤75°.

[0051] In the system provided by the present invention, the connecting rod 802 can be in a horizontal state or in an inclined state. However, when in an inclined state, the end connected to the detection spoon is inclined upward, and the inclination angle is not too large, and is required to be no higher than 75°. If it is too high, the detection spoon cannot collect the detection sample well, so that the connecting rod 802 cannot be effectively and timely tilted.

[0052] Furthermore, if Figure 2 As shown, the upper static contact 805 is provided with two upper contacts 8501; the static contact 807 is provided with two lower contacts 8071; the movable contact 806 is an H-shaped structure, and two contacts matching the positions of the upper contacts 8501 are provided on the upper part of the movable contact 806; and two contacts matching the positions of the lower contacts 8071 are provided on the lower part of the movable contact 806. Sensors capable of sensing whether the movable contact 806 is in contact with them are respectively provided on the two upper contacts 8501 and the two lower contacts 8071, and the sensors are electrically connected to the controller 2.

[0053] Furthermore, in the present invention, a spring sleeve 808 is sleeved on the outside of the spring 804 , and the spring sleeve 808 penetrates and is fixed on the upper shell wall of the shell 809 .

[0054] The present invention can protect the stretching of the spring 804 from being affected by the outside world by sleeve-arranging the spring sleeve 808 on the outside of the spring 804, thereby improving the sensitivity of the entire device.

[0055] Furthermore, a feed pipe is provided below the silo 1, and a feed valve 4 is provided on the feed pipe; a blower 3 is provided at the inlet of the feed pipe; and a sensor capable of sensing a transport vehicle is provided at the outlet of the discharge branch pipe 71. The sensor capable of sensing a transport vehicle, the feed valve 4, and the blower 3 are all electrically connected to the controller 2.

[0056] Specifically, when the sensor senses that a transport vehicle has arrived under the discharge branch pipe 71, the controller 2 controls the blower 3 and the feed valve 4 to open, and the blower 3 is used to discharge the alumina powder into the silo 1. When the alumina powder stored in the silo 1 reaches the preset requirements, the discharge valve 6 is opened to start discharging. While discharging, a portion of the alumina powder falls into the transport vehicle through the discharge branch pipe 71, and a portion of the alumina powder is output as a test sample through the sampling branch pipe 72 and finally falls onto the conveying device 10 for collection and testing by the test personnel.

[0057] The system provided by the present invention arranges a sensor below the discharge branch pipe 71 so that the controller can determine whether to open or close the discharge valve 6 according to the presence or absence of a vehicle, thereby avoiding the misunderstanding of discharging materials without a transport vehicle.

[0058] The conveying device 10 may be a transmission belt or a spiral conveying mechanism, and the present application does not impose any limitation thereto, as long as it can ensure that the test samples flowing out of the sampling branch pipe 72 can be effectively collected.

[0059] Furthermore, the bottom of the silo 1 is a conical structure, and an electric rapper 5 is arranged outside the side wall of the conical structure of the silo 1 , and the electric rapper 5 is electrically connected to the controller 2 .

[0060] Specifically, the electric rapper 5 is used to prevent the aluminum oxide powder in the conical silo 1 from scarring and clogging.

[0061] The system provided by the present invention prevents the alumina powder from clogging the discharge pipe by arranging an electric vibrator 5 below the silo 1, thereby improving the discharge efficiency and the sampling efficiency.

[0062] The present invention also provides a sampling method based on the automatic periodic sampling system for bulk alumina, the method comprising the following steps:

[0063] 1. Turn on the blower 3 and the feed valve 4 through the controller 2 to blow the alumina powder into the silo 1 until the amount of alumina powder meets the requirement, and then turn off the blower 3 and the feed valve 4.

[0064] 2. Determine whether there is a transport vehicle under the discharge branch pipe 71. If there is a transport vehicle, determine the total amount of alumina powder to be transported, and determine the opening time of the discharge valve 6 and the sampling valve 9 according to the total amount of alumina powder to be transported; the sampling valve 9 is opened several times; each time is 5 minutes apart, and the initial single opening time is 5 minutes.

[0065] Specifically, the opening and closing of the discharge valve 6 is used to control the amount of alumina powder loaded on the transport vehicle; the sampling valve 9 is used to take samples during the loading process to determine the quality of the alumina powder of the batch. By controlling the sampling valve 9 to open multiple times for sampling, the quality of the alumina powder loaded on the transport vehicle can be more accurately controlled.

[0066] 3. Turn on the electric vibrator 5, and simultaneously open the discharge valve 6 and the sampling valve 9, so that the alumina powder in the silo 1 falls into the discharge branch pipe 71 and the sampling branch pipe 72 respectively through the discharge pipe 7; the alumina powder falling from the sampling branch pipe 72 is collected by the sampling collection mechanism.

[0067] Specifically, the electric vibrator is turned on to prevent the aluminum oxide powder in the silo 1 from being clogged. The aluminum oxide powder in the silo 1 is knocked by the electric vibrator, so that the aluminum oxide powder falls into the transport vehicle evenly and effectively. At the same time, the sampling valve 9 is used to monitor the quality of the aluminum oxide powder loaded on the transport vehicle in real time, so that the quality of the loaded aluminum oxide powder can be controlled more accurately.

[0068] 4. Turn on the material flow switch 8, and determine the material flow state of the magnesium oxide powder falling into the sampling branch pipe 72 through the material flow switch 8; when the material flow switch 8 detects that no magnesium oxide powder has fallen into the sampling branch pipe 72, immediately close the discharge valve 6 and the sampling valve 9 for maintenance until magnesium oxide powder falls into the sampling branch pipe 72; when the material flow switch 8 detects that a small amount of magnesium oxide powder has fallen into the sampling branch pipe 72, adjust the single opening time and opening degree of the sampling valve 9 according to the current magnesium oxide powder material flow rate.

[0069] Specifically, since the flow rate of magnesium oxide powder falling into the sampling branch pipe 72 can be large or small (the size of its flow rate is controlled by the discharge valve 6), and in the sampling process, different flow rates are required for different sampling and collection mechanisms to prevent the magnesium oxide powder from overflowing due to excessive flow rate, or the sampling speed is too low due to too small flow rate, thereby reducing the efficiency of monitoring the quality of magnesium oxide powder. Therefore, the present invention monitors the flow rate of the sampling branch pipe through a flow switch, and determines the opening time and opening degree of the sampling valve 9 by monitoring the flow rate. If the flow rate is large, the opening degree and opening time of the sampling valve 9 can be adjusted according to actual needs to achieve the goal of reasonable sampling.

[0070] 5. When the first sampling time of the sampling valve 9 ends, close the sampling valve 9 and the material flow switch 8, and open the sampling valve 9 and the material flow switch 8 again after the second sampling time of the sampling valve 9 begins.

[0071] Specifically, since magnesium oxide powder is susceptible to moisture and moisture absorption during storage, it deteriorates. When it is exposed to the air, it absorbs moisture from the air, resulting in a decrease in its active content, affecting the use effect. If it encounters humid weather, it may deteriorate. In particular, if an accident occurs in the silo and the workers are unaware of it, the magnesium oxide powder may also deteriorate. Therefore, by opening and closing the sampling valve 9 multiple times to perform multiple sampling monitoring, the quality of the magnesium oxide powder loaded on the transport vehicle can be effectively and accurately grasped.

[0072] 6. Repeat the opening and closing of the sampling valve 9 and the material flow switch 8 until the cargo capacity of the transport vehicle reaches the requirement, and then close the electric vibrator 5, the discharge valve 6, the material flow switch 8, and the sampling valve 9.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An automatic periodic sampling system for bulk alumina, comprising: A silo (1) for storing alumina powder, wherein a discharge pipe (7) is arranged at the bottom of the silo (1), characterized in that two branch pipes are opened below the discharge pipe (7), namely a discharge branch pipe (71) and a sampling branch pipe (72); A discharge valve (6) is provided between the discharge pipe (7) and the inlet of the discharge branch pipe (71); A sampling valve (9) is provided between the outlet of the sampling branch pipe (72) and the inlet of the discharge branch pipe (71); The discharge valve (6) and the sampling valve (9) are electrically connected to the controller (2) respectively.

2. The automatic periodic sampling system for bulk alumina according to claim 1, characterized in that: A material flow switch (8) for determining the sample flow rate is arranged on the sampling branch pipe (72), and the material flow switch (8) is electrically connected to the controller (2).

3. The automatic periodic sampling system for bulk alumina according to claim 2, characterized in that: The material flow switch (8) comprises: A connecting rod (802), the connecting rod (802) is sealingly and movably connected to the tube wall of the sampling branch tube (72), one end of the connecting rod (802) is fixed with a detection spoon (801), and the other end is fixed with a connection block (803); the detection spoon (801) is inside the sampling branch tube (72); the connection block (803) is outside the sampling branch tube (72); A housing (809), wherein the connection block (803) is arranged above the housing (809); A spring (804), one end of the spring (804) is fixed to the bottom of the connecting block (803), and the other end of the spring (804) passes through the housing (809), and a moving contact (806) is fixed to the end thereof; An upper static contact (805) and a lower static contact (807) are fixed to the top and bottom of the shell (809), respectively; under the tension of the spring (804), the moving contact (806) can contact the upper static contact (805) or disconnect from the lower static contact (807) to trigger a material flow signal and transmit it to the controller (2).

4. The automatic periodic sampling system for bulk alumina according to claim 3, characterized in that: The angle between the connecting rod (802) and the horizontal plane is: 0°≤angle≤75°.

5. The automatic periodic sampling system for bulk alumina according to claim 3, characterized in that: The upper static contact (805) is provided with two upper contacts (8501); the static contact (807) is provided with two lower contacts (8071); The movable contact (806) is an H-shaped structure, and two contacts matching the position of the upper contact (8501) are arranged on the upper part of the movable contact (806); and two contacts matching the position of the lower contact (8071) are arranged on the lower part of the movable contact (806).

6. The automatic periodic sampling system for bulk alumina according to claim 3, characterized in that: A spring sleeve (808) is sleeved on the outside of the spring (804), and the spring sleeve (808) penetrates and is fixed on the upper shell wall of the shell (809).

7. The automatic periodic sampling system for bulk alumina according to any one of claims 1 to 6, characterized in that: A feed pipe is provided below the silo (1), and a feed valve (4) is provided on the feed pipe; a blower (3) is provided at the inlet of the feed pipe; and a sensor capable of sensing a transport vehicle is provided at the outlet of the discharge branch pipe (71); The sensor capable of sensing the transport vehicle, the feed valve (4), and the blower (3) are all electrically connected to the controller (2).

8. The automatic periodic sampling system for bulk alumina according to claim 1, characterized in that: A conveying device for conveying aluminum oxide samples is provided below the outlet of the sampling branch pipe (72).

9. The automatic periodic sampling system for bulk alumina according to claim 1, characterized in that: The bottom of the silo (1) is a conical structure, and an electric vibrator (5) is arranged outside the side wall of the conical structure of the silo (1), and the electric vibrator (5) is electrically connected to the controller (2).

10. A sampling method based on the automatic periodic sampling system for bulk alumina according to claim 1, characterized in that: The following steps are involved: (1), opening the blower (3) and the feed valve (4) through the controller (2) to blow the aluminum oxide powder into the silo (1) until the amount of the aluminum oxide powder meets the requirement, and then closing the blower (3) and the feed valve (4); the blower (3) is arranged at the inlet of the feed pipe below the silo (1); the feed valve (4) is arranged on the feed pipe; (2) determining whether there is a transport vehicle below the discharge branch pipe (71); if there is a transport vehicle, determining the total amount of alumina powder to be transported, and determining the opening time of the discharge valve (6) and the sampling valve (9) according to the total amount of alumina powder to be transported; the sampling valve (9) is opened several times; each time is 5 minutes apart, and the initial single opening time is 5 minutes; (3) turning on the electric vibrator (5), and simultaneously opening the discharge valve (6) and the sampling valve (9), so that the alumina powder in the silo (1) respectively falls into the discharge branch pipe (71) and the sampling branch pipe (72) through the discharge pipe (7); the alumina powder falling from the sampling branch pipe (72) is collected by the sampling collection mechanism; The electric rapper (5) is arranged on the side wall of the silo (1); (4) Turning on the material flow switch (8), and determining the material flow state of the magnesium oxide powder falling into the sampling branch pipe (72) through the material flow switch (8); when the material flow switch (8) detects that no magnesium oxide powder has fallen into the sampling branch pipe (72), immediately closing the discharge valve (6) and the sampling valve (9) for maintenance until magnesium oxide powder falls into the sampling branch pipe (72); when the material flow switch (8) detects that a small amount of magnesium oxide powder has fallen into the sampling branch pipe (72), adjusting the single opening time of the sampling valve (9) according to the current magnesium oxide powder material flow rate; The material flow switch (8) is arranged on the sampling branch pipe (72); (5) When the first sampling time of the sampling valve (9) ends, the sampling valve (9) and the material flow switch (8) are closed until the second sampling time of the sampling valve (9) begins, and then the sampling valve (9) and the material flow switch (8) are opened again; (6) The sampling valve (9) and the material flow switch (8) are repeatedly opened and closed until the cargo load of the transport vehicle reaches the required amount, and then the electric vibrator (5), the discharge valve (6), the material flow switch (8) and the sampling valve (9) are closed.

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