Pneumatic lifting system and pneumatic lifting method for seabed ore

Abstract

The invention discloses an air lift system and an air lift method for seabed ore, the air lift system comprises a lift pipe and an air compressor, a compressed air outlet of the air compressor is connected with the lift pipe through an air transmission header pipe, and an outlet of the lift pipe is connected with a backpressure cylinder; when the lifting pipe discharges solid-gas-liquid three-phase fluid into the back pressure cylinder, first pressure is kept in the back pressure cylinder, the first pressure is positive pressure, a gas outlet is formed in the back pressure cylinder, and a gas outlet is formed in the back pressure cylinder; and a first valve used for adjusting the first pressure in the backpressure cylinder so as to control the flow velocity of the solid-gas-liquid three-phase fluid in the lifting pipe is arranged at the gas outlet. According to the pneumatic lifting system and method, the back pressure cylinder is additionally arranged at the outlet of the lifting pipe of the pneumatic lifting system, expansion of compressed air is reduced, and the flow speed of solid-gas-liquid three-phase fluid at the outlet of the lifting pipe can be greatly reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of deep - sea mining, and particularly relates to a pneumatic lifting system and a pneumatic lifting method for mineral transportation. Background Technique

[0002] Mineral resources, as an important natural resource, are an important material basis for the production and development of human society. In deep - sea mining systems, pneumatic lifting and hydraulic lifting are recognized as ore - lifting methods with industrial application prospects. Compared with hydraulic lifting, the air compressor of pneumatic lifting is installed on the mining ship, and there are no moving parts underwater, which has the advantages of convenient operation and maintenance, and simple and reliable process.

[0003] In a deep - sea mining pneumatic lifting system, the lower part of the air injection port is a solid - liquid two - phase flow, and the upper part of the air injection port is a solid - liquid - gas three - phase flow. The depth of the air injection port is generally between 2000 - 2500 m, and the seawater temperature here is about 2 - 3 °C. Under such high - pressure and low - temperature conditions, the compression, expansion, and dissolution of air in seawater become particularly prominent. During the upward process of the three - phase flow, due to the gradually decreasing pressure, the rising bubbles will continuously expand, and the flow velocity in the pipe will continuously increase. Especially near the sea surface, the flow velocity of the three - phase flow in the lifting pipe will become very high. According to the analysis of existing data, the air flow velocity at the outlet of the lifting pipe in a deep - sea mining pneumatic lifting system is about 30 - 50 m / s. Too high a flow velocity will accelerate the wear of pipelines and equipment, the degree of fragmentation and pulverization of nodule particles is serious, which is not conducive to the service life of pipelines and the sedimentation of pulp on the ship, and the lifting energy consumption and cost will increase.

[0004] Therefore, measures must be taken to reduce the flow velocity of the three - phase flow in the lifting pipe. The measures taken in the prior art are as follows: A stepped variable - diameter pipe is used in the upper part of the pneumatic lifting system to expand the pipe diameter. However, the disadvantage of this measure is that the larger the pipe diameter, the higher the manufacturing cost of the pipeline, the larger the occupied space on the ship's deck, and the greater the difficulty of deployment, recovery, and maintenance. Therefore, it is necessary to propose a new measure to reduce the flow velocity of the three - phase flow in the lifting pipe of the pneumatic lifting system. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the above - mentioned deficiencies and defects in the background technique, and provide a pneumatic lifting system with a back - pressure device for reducing the flow velocity of the three - phase fluid at the outlet of the lifting pipe and a pneumatic lifting method for seabed ore.

[0006] To solve the above - mentioned technical problem, the technical solution proposed by the present invention is as follows: A pneumatic lifting system with a backpressure device, comprising a lifting pipe and an air compressor. The compressed air outlet of the air compressor is connected to the lifting pipe through a main gas transmission pipe. The outlet of the lifting pipe is connected to a backpressure cylinder. When the solid-gas-liquid three-phase fluid is discharged from the lifting pipe into the backpressure cylinder, the inside of the backpressure cylinder maintains a first pressure, and the first pressure is a positive pressure. The backpressure cylinder is provided with a gas discharge port, and a first valve is provided at the gas discharge port for adjusting the magnitude of the first pressure inside the backpressure cylinder to control the flow rate of the solid-gas-liquid three-phase fluid in the lifting pipe.

[0007] In the above pneumatic lifting system, preferably, one end of the first valve is connected to the gas discharge port, and the other end of the first valve is connected to the inlet of a booster through a first gas transmission pipe. The outlet of the booster is connected to the main gas transmission pipe through a second gas transmission pipe, and a check valve is provided on the second gas transmission pipe. In the present invention, air with a certain pressure is transported to the booster for pressurization through the first valve and the first gas transmission pipe, and then sent to the main gas transmission pipe through the second gas transmission pipe, realizing the recycling of air with a certain pressure. The air compressor is used to supplement compressed gas, which can further improve the efficiency of the air compressor and the pneumatic lifting system. At the same time, for the recycling of compressed air, the discharge of air with fine particles of polymetallic nodules is avoided, which has an impact on the environment on the mining ship. The above check valve only allows gas to pass unidirectionally, and only allows air to be transported from the second gas transmission pipe to the main gas transmission pipe and cannot flow reversely.

[0008] In the above pneumatic lifting system, preferably, one end of the first valve is connected to the gas discharge port through a tee pipe, and the other end of the tee pipe is provided with a second valve for communicating the backpressure cylinder with the outside (or the atmosphere). The opening or closing of the second valve can be used to control the connection between the backpressure cylinder and the outside, facilitating the control of the pressure regulation inside the backpressure cylinder.

[0009] In the above pneumatic lifting system, preferably, a cleaning device for cleaning gas is provided on the first gas transmission pipe. The cleaning device sequentially includes a refrigerated dryer and a filter according to the gas flow direction. The refrigerated dryer and the filter can be used to clean the air discharged from the backpressure cylinder to avoid affecting the booster.

[0010] In the above pneumatic lifting system, preferably, a buffer is provided in the backpressure cylinder for buffering the acting force of the solid-gas-liquid three-phase fluid discharged from the outlet of the lifting pipe. The buffer can buffer the acting force of the solid-gas-liquid three-phase fluid discharged from the lifting pipe, reduce the crushing rate of solid-phase particles, and is beneficial to the sedimentation separation of the solid and liquid phases.

[0011] In the above pneumatic lifting system, preferably, the outlet of the lifting pipe is located at the middle position of the back-pressure cylinder body, and the buffer is arranged opposite to the outlet of the lifting pipe; the buffer includes a metal disc, wear-resistant rubber, a buffer spring, a connecting rod and a guide cylinder. The wear-resistant rubber is arranged on the surface of the metal disc, facing the outlet of the lifting pipe. The center of the metal disc and the center of the outlet of the lifting pipe are on the same axis. The guide cylinder is located on the outer wall of the back-pressure cylinder body. One end of the metal disc is connected to one end of the connecting rod, and the other end of the connecting rod is movably located in the guide cylinder. The buffer spring is sleeved on the connecting rod and is clamped between the metal disc and the inner wall of the back-pressure cylinder body. The solid-phase polymetallic nodules in the solid-gas-liquid three-phase fluid are coarse-grained ores with a diameter of several centimeters. The severe fragmentation and pulverization of the polymetallic nodule particles affect the sedimentation of the pulp in the storage bin on the mining ship, and the discharge of fine particles will increase the metal loss. In the present invention, with the buffer having the above structure, when the three-phase mixture of compressed air, seawater and polymetallic nodules enters the back-pressure cylinder body from the outlet of the lifting pipe, the two-phase mixture of seawater and polymetallic nodules acts on the metal disc with wear-resistant rubber. Under the action of the buffer spring, the connecting rod makes a reciprocating motion in the guide cylinder, reducing the impact force of the polymetallic nodule particles and reducing the fragmentation and pulverization of the polymetallic nodule particles.

[0012] In the above pneumatic lifting system, preferably, the bottom outlet of the back-pressure cylinder body is connected to a storage bin through a connecting pipe. The diameter of the connecting pipe is 1.5 - 2 times the diameter of the lifting pipe. A seawater discharge pipe is connected to the connecting pipe through a third valve. When lifting the seabed ore, the solid-liquid two-phase in the back-pressure cylinder body will enter the storage bin through the connecting pipe for further sedimentation and separation. When the lifting is completed, by opening the third valve, the seawater in the back-pressure cylinder body and the storage bin can be discharged outside through the seawater discharge pipe. The diameter of the bottom outlet pipe of the back-pressure cylinder body (i.e., the connecting pipe) is larger than the diameter of the lifting pipe, which is beneficial to the transfer of the solid-liquid two-phase in the back-pressure cylinder body. Generally, the diameter of the connecting pipe is 1.5 - 2 times the diameter of the lifting pipe. For example, if the diameter of the lifting pipe is 200 mm, the diameter of the connecting pipe is about 300 - 400 mm.

[0013] In the above pneumatic lifting system, preferably, the top overflow outlet of the storage bin is connected to a secondary sedimentation tank. An overflow water pipe is arranged at the top of the secondary sedimentation tank. A seawater conveying pipe is connected to the storage bin. The inlet end of the seawater conveying pipe is located below the sea surface, and a submersible pump is arranged at the end.

[0014] In the above pneumatic lifting system, preferably, when the lifting pipe discharges the solid-gas-liquid three-phase fluid into the back-pressure cylinder body, there is a liquid seal in the back-pressure cylinder body, and the liquid level height in the back-pressure cylinder body is the same as the liquid level height in the storage bin.

[0015] The solid and liquid phases entering the storage tank from the backpressure cylinder settle and separate within the tank. The polymetallic nodules freely settle to the bottom of the tank, while the seawater containing mud and fine-grained nodules overflows into the secondary sedimentation tank for secondary sedimentation. The resulting seawater is then discharged into the sea through an overflow pipe. Before the seabed minerals are lifted, seawater is delivered to the storage tank and backpressure cylinder via a seawater delivery pipe, maintaining the same liquid level. During the three-phase flow process, the liquid levels in the backpressure cylinder and the storage tank remain at the same level.

[0016] As a general technical concept, the present invention also provides a method for pneumatically lifting seabed ore using the above-mentioned pneumatic lifting system, comprising the following steps: S1: connecting the back pressure cylinder to the outside and adding seawater into the back pressure cylinder; S2: The communication passage between the back-pressure cylinder and the outside is closed, and the air compressor is started. The compressed air compressed by the air compressor is delivered to the riser through the gas main. Due to the injection of compressed air, the seabed ore is sucked from the bottom of the riser and lifted to the outlet of the riser, and discharged into the back-pressure cylinder as a solid-gas-liquid three-phase fluid. During the lifting process, the back-pressure cylinder maintains a positive pressure, and the flow rate of the solid-gas-liquid three-phase fluid in the riser is adjusted by the opening and closing degree of the first valve. S3: After the seabed ore is lifted, the air compressor is turned off, and the back pressure cylinder is connected to the outside to release the pressure inside.

[0017] The working process of the pneumatic lifting system of the present invention is roughly as follows: A three-phase mixture of compressed air, seawater and polymetallic nodules enters the back-pressure cylinder from the outlet of the riser. The compressed air in the three-phase mixture is separated from the seawater and polymetallic nodules in the back-pressure cylinder. The separated compressed air is recycled through the first valve at the upper part of the back-pressure cylinder. The separated seawater and polymetallic nodules freely settle into the connecting pipe at the lower part of the back-pressure cylinder and are transported to the storage tank on the mining ship through the connecting pipe. The polymetallic nodules freely settle to the bottom of the storage tank. The seawater flows into the secondary sedimentation tank through the storage tank for sedimentation. The settled seawater is discharged underwater through the overflow pipe.

[0018] The working principle of the pneumatic lifting system of the present invention is roughly as follows: Compressed air is injected into the riser at an appropriate seawater depth. Since the density of the solid-gas-liquid three-phase mixture formed by the compressed air, seawater in the pipe, and polymetallic nodules is smaller than the density of the seawater outside the riser, a density difference is generated inside and outside the pipe, forming an upwelling of seawater in the pipe and lifting the polymetallic nodules to the sea surface. The lower part of the riser below the air injection port is a solid-liquid two-phase flow, and the pressure inside the pipe is lower than the pressure outside the pipe. The polymetallic nodules are lifted by the potential energy of the seawater. The upper part of the riser above the air injection port is a solid-liquid-gas three-phase flow, and the pressure inside the pipe is higher than the pressure outside the pipe. The polymetallic nodules are lifted by the pressure of the compressed air discharged by the air compressor.

[0019] According to the working principle of pneumatic pipeline lifting, the pressure inside the pipe below the air injection port is less than the pressure outside the pipe, and the pressure inside the pipe above the air injection port is greater than the pressure outside the pipe. The outlet of the riser still maintains a certain internal pressure. The three-phase mixture with this internal pressure is separated in the back-pressure cylinder, and the separated seawater and polymetallic nodules form a liquid level in the back-pressure cylinder. If the second valve is opened and the first valve is closed, the separated compressed air is discharged into the atmosphere, and no positive pressure can be formed in the back-pressure cylinder, and the flow rate of the three-phase flow in the riser is not reduced. When the second valve is closed and the first valve is opened, the compressed air is discharged into the first gas pipeline, and a positive pressure is formed in the back-pressure cylinder, which can reduce the flow rate of the three-phase flow in the riser. By adjusting the opening degree of the first valve, the flow rate of the three-phase flow in the riser can be further adjusted. Specifically, when the opening degree of the first valve is reduced, the positive pressure in the back-pressure cylinder increases, and the flow rate of the three-phase flow in the riser can be reduced. However, if the flow rate of the three-phase flow in the riser is reduced to the critical flow rate, the pneumatic lifting system will not work properly, the density and pressure loss of the three-phase mixture increase, and pipeline blockage may occur.

[0020] Compared with the prior art, the advantages of the present invention are as follows: 1. The pneumatic lifting system and method with a back-pressure device of the present invention add a back-pressure cylinder at the outlet of the riser of the pneumatic lifting system, which reduces the expansion of the compressed air, can greatly reduce the flow rate of the solid-gas-liquid three-phase fluid at the outlet of the riser, reduce the frictional resistance loss in the riser, will not cause excessive fragmentation of mineral particles, is beneficial to the service life of the riser, and improves the efficiency of the pneumatic lifting system. At the same time, by setting a first valve on the back-pressure cylinder, the magnitude of the first pressure in the back-pressure cylinder can be adjusted by the opening degree of the first valve, and the flow rate of the solid-gas-liquid three-phase fluid in the riser can be indirectly adjusted, so as to meet the requirements of various conveying working conditions.

[0021] 2. The pneumatic lifting system and method with a backpressure device of the present invention is an energy-saving device with a simple structure, low cost, easy operation and easy maintenance, which can fully meet the technical requirements of the pneumatic lifting system for deep-sea mining. The successful research and development of this backpressure device can fill the gap in the pneumatic lifting system for deep-sea mining in China. On the one hand, it can be applied to the pneumatic lifting system for deep-sea mining, and on the other hand, it can also be applied to fields such as pneumatic coal mining and land-based underwater mining, promoting the rapid development of China's deep-sea mining technology and bringing the development and research technology of China's pneumatic lifting system for deep-sea mining to the international advanced level. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0023] Figure 1 FIG. is a schematic structural diagram of the pneumatic lifting system with a backpressure device of the present invention.

[0024] Figure 2 FIG. is a schematic structural diagram at the buffer of the pneumatic lifting system with a backpressure device of the present invention.

[0025] LEGEND DESCRIPTION 1. Lifting pipe; 2. Air injection port; 3. Seawater discharge pipe; 4. Overflow water pipe; 5. Submersible pump; 6. Seawater delivery pipe; 7. Secondary sedimentation tank; 8. Storage bin; 9. Third valve; 10. Connecting pipe; 11. Buffer spring; 12. Link; 13. Guide cylinder; 14. Metal disc; 15. Wear-resistant rubber; 16. Backpressure cylinder body; 17. Second valve; 18. Three-way pipe; 19. First valve; 20. Cold dryer; 21. Filter; 22. First gas transmission pipe; 23. Booster; 24. Second gas transmission pipe; 25. Check valve; 26. Gas transmission main pipe; 29. Air compressor; 30. Mining ship. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] For the convenience of understanding the present invention, the following will describe the present invention more comprehensively and meticulously in combination with the accompanying drawings of the specification and preferred embodiments. However, the protection scope of the present invention is not limited to the following specific embodiments.

[0027] It should be particularly noted that when an element is described as "fixed to, fixedly connected to, connected to or communicated with" another element, it can be directly fixed, fixedly connected, connected or communicated to the other element, or indirectly fixed, fixedly connected, connected or communicated to the other element through other intermediate connecting members.

[0028] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those commonly understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention.

[0029] Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment, etc. used in the present invention can be obtained through market purchase or can be prepared by existing methods.

[0030] Example: As Figure 1 shown, the pneumatic lifting system with a backpressure device in this embodiment includes a riser 1 and an air compressor 29. The compressed air outlet of the air compressor 29 is connected to the riser 1 through a main gas pipeline 26. The outlet of the riser 1 is connected to a backpressure cylinder 16. When the riser 1 discharges a solid-gas-liquid three-phase fluid into the backpressure cylinder 16, the inside of the backpressure cylinder 16 maintains a first pressure, and the first pressure is a positive pressure. The backpressure cylinder 16 is provided with a gas discharge port, and a first valve 19 (automatic control valve) is provided at the gas discharge port for adjusting the magnitude of the first pressure inside the backpressure cylinder 16 to control the flow rate of the solid-gas-liquid three-phase fluid in the riser 1.

[0031] In this embodiment, one end of the first valve 19 is connected to the gas discharge port, and the other end of the first valve 19 is connected to the inlet of a booster 23 through a first gas pipeline 22. The outlet of the booster 23 is connected to the main gas pipeline 26 through a second gas pipeline 24, and a check valve 25 is provided on the second gas pipeline 24.

[0032] In this embodiment, one end of the first valve 19 and the gas discharge port are connected through a tee 18, and the other end of the tee 18 is provided with a second valve 17 (automatic control valve) for communicating the backpressure cylinder 16 with the outside.

[0033] In this embodiment, a cleaning device for cleaning the gas is provided on the first gas pipeline 22. The cleaning device sequentially includes a refrigerated dryer 20 and a filter 21 according to the gas flow direction.

[0034] In this embodiment, a buffer for buffering the acting force of the solid-gas-liquid three-phase fluid discharged from the outlet of the riser 1 is provided in the backpressure cylinder 16. Specifically, as Figure 2As shown, the outlet of the riser 1 is located at the middle position of the backpressure cylinder 16, and the buffer is arranged opposite to the outlet of the riser 1; the buffer includes a metal disk 14, wear-resistant rubber 15, a buffer spring 11, a connecting rod 12 and a guide cylinder 13. The wear-resistant rubber 15 is arranged on the surface of the metal disk 14, facing the outlet of the riser 1. The guide cylinder 13 is located on the outer wall of the backpressure cylinder 16. One end of the metal disk 14 is connected to one end of the connecting rod 12, and the other end of the connecting rod 12 is movably located in the guide cylinder 13. The buffer spring 11 is sleeved on the connecting rod 12 and is clamped between the metal disk 14 and the inner wall of the backpressure cylinder 16.

[0035] In this embodiment, the bottom outlet of the backpressure cylinder 16 is connected to a storage bin 8 through a connecting pipe 10. The diameter of the connecting pipe 10 is 1.5 - 2 times that of the riser 1. A seawater discharge pipe 3 is connected to the connecting pipe 10 through a third valve 9 (automatic control valve). The top overflow outlet of the storage bin 8 is connected to a secondary sedimentation tank 7. An overflow water pipe 4 is arranged at the top of the secondary sedimentation tank 7. A seawater delivery pipe 6 is connected to the storage bin 8. The inlet end of the seawater delivery pipe 6 is located below the sea surface, and a submersible pump 5 is arranged at the end.

[0036] In this embodiment, when the riser 1 discharges the solid-gas-liquid three-phase fluid into the backpressure cylinder 16, there is a liquid seal in the backpressure cylinder 16, and the liquid level height in the backpressure cylinder 16 is the same as the liquid level height in the storage bin 8.

[0037] In this embodiment, the volume of the backpressure cylinder 16 is determined by the flow rate of the three-phase flow. The volume of the cylinder increases with the increase of the flow rate of the three-phase flow. Generally, for example, when the pulp flow rate is 360 m ,

[0037] , ,

[0036] , 3 , 3 , ,

[0038] / h and the three-phase flow transportation time is about 15 - 20 s, the volume of the cylinder is about 1.5 - 2 m 3 , this volume can meet the requirements of air separation and free settlement of polymetallic nodules. There are certain requirements for the positional relationship between the outlet of the riser 1 and the backpressure cylinder 16 and the positions of the gas, solid and liquid outlets of the backpressure cylinder 16 to ensure the separation effect of compressed air from seawater polymetallic nodules in the backpressure cylinder 16. If the inlet position of the three-phase fluid, the outlet positions of the compressed air, solid and liquid, and the diameter arrangement of the connecting pipe 10 are unreasonable, the separation effect will be affected. In this embodiment, the outlet of the riser 1 is arranged in the middle of the backpressure cylinder 16 and is fixed to the outer surface of the side part of the backpressure cylinder 16. The outlet position of the compressed air is arranged at the top of the backpressure cylinder 16 and is fixed to the outer top surface of the backpressure cylinder 16. The diameter of the connecting pipe 10 is larger than that of the riser 1. The connecting pipe 10 is arranged at the bottom of the backpressure cylinder 16 and is fixed to the outer bottom surface of the backpressure cylinder 16. Generally, the diameter of the connecting pipe 10 is 1.5 - 2 times that of the riser 1. For example, if the diameter of the riser 1 is 200 mm, the diameter of the connecting pipe 10 is about 300 - 400 mm.

[0038] The pneumatic lifting method for seabed ore using the above pneumatic lifting system in this embodiment includes the following steps: S1: Connect the backpressure cylinder 16 to the outside and add seawater into the backpressure cylinder 16; S2: Close the communication channel between the backpressure cylinder 16 and the outside, start the air compressor 29, and the compressed air compressed by the air compressor 29 is conveyed to the riser 1 through the main gas pipeline 26. Due to the injection of the compressed air, the seabed ore is sucked from the bottom of the riser 1 and lifted to the outlet of the riser 1, and discharged as a solid-gas-liquid three-phase fluid into the backpressure cylinder 16; during the lifting process, a positive pressure is maintained in the backpressure cylinder 16, and the flow rate of the solid-gas-liquid three-phase fluid in the riser 1 is adjusted by the opening degree of the first valve 19; S3: After the seabed ore is lifted, turn off the air compressor 29, connect the backpressure cylinder 16 to the outside, and release the pressure inside it.

[0039] More specifically, the pneumatic lifting method may include the following steps: Before lifting, close the third valve 9, open the first valve 19 and the second valve 17, start the submersible pump 5, the seawater is conveyed to the storage bin 8 through the seawater pipeline 6, and then flows into the backpressure cylinder 16 through the connecting pipe 10. When the liquid levels of the backpressure cylinder 16 and the storage bin 8 are at the same height, the seawater in the storage bin 8 flows into the secondary sedimentation tank 7 and is discharged into the sea through the overflow pipe 4. At this time, stop the submersible pump 5 and close the second valve 17.

[0040] During lifting, the air compressor 29 is started. The atmosphere enters the air compressor 29 from the inlet of the air compressor 29 and is compressed inside. The compressed air after compression is transported to the air injection port 2 through the main air delivery pipe 26, and then transported to the outlet of the riser 1 through the riser 1. The compressed air and the seawater in the riser 1 form an upward flow. The bubbles of the upward flow will continuously expand, and the flow velocity in the riser 1 will continuously increase, thus forming a density difference inside and outside the pipe, so as to suck the polymetallic nodules on the seabed from the bottom of the riser 1 and lift them to the outlet. The solid-liquid phase of the three-phase mixture at the outlet of the riser 1 is separated from the compressed air in the back-pressure cylinder 16. The separated solid-liquid phase directly impacts the surface of the metal disc 14 bonded with the wear-resistant rubber 15. Under the action of the buffer spring 11, the seawater and the polymetallic nodules freely settle to the lower part of the back-pressure cylinder 16 and are transported to the storage bin 8 through the connecting pipe 10. The polymetallic nodules freely settle in the storage bin 8, and the seawater flows into the secondary sedimentation tank 7. The sedimented seawater is discharged into the sea through the overflow water pipe 4. The separated compressed air is at the upper part of the back-pressure cylinder 16 and is transported to the booster 23 through the three-way pipe 18, the first valve 19, the cold dryer 20, the filter 21, and the first air delivery pipe 22. The compressed air is subjected to secondary cyclic pressurization under the action of the booster 23 and is transported to the air injection port 2 through the second air delivery pipe 24, the check valve 25, and the main air delivery pipe 26 to realize the secondary utilization of the compressed air. In addition, when the booster 23 is working, the air compressor 29 automatically stops working. When there is air volume loss in the pipelines and equipment during the air delivery process, the air compressor 29 automatically starts to meet the air volume requirements of the pneumatic lifting system. In addition, according to the technical requirements of the pneumatic lifting system, the flow velocity of the three-phase fluid at the outlet of the riser 1 can be controlled by adjusting the opening degree of the first valve 19.

[0041] At the end of lifting, the supply of polymetallic nodules to the bottom of the riser 1 is stopped. When seawater is discharged from the outlet of the riser 1, the booster 23 and the air compressor 29 are sequentially closed, and the second valve 17 is opened to discharge the remaining compressed air in the riser 1 and the back-pressure cylinder 16. After a period of time, the third valve 9 is opened, and the seawater in the back-pressure cylinder 16 and the storage bin 8 is discharged into the sea through the seawater discharge pipe 3, and the polymetallic nodules are collected.

[0042] In each of the above steps, the entire process of starting, running, and stopping of each device and valve is monitored, measured, and controlled by the remote monitoring and control station on the mining ship 30. The working conditions of the equipment in each starting step and process are clearly displayed on the computer screen. If there are problems during the starting or running process, an alarm signal will be issued.

[0043] The pneumatic lifting system with a backpressure device in this embodiment can adjust the flow rate of the three-phase fluid at the outlet of the riser 1 through the setting of the backpressure cylinder 16 and the first valve 19, reduce the frictional resistance loss in the riser 1, prevent excessive crushing of mineral particles, be beneficial to the service life of the riser 1, and improve the efficiency of the pneumatic lifting system. At the same time, the opening degree of the first valve 19 can be used to adjust the magnitude of the first pressure in the backpressure cylinder 16, and indirectly adjust the flow rate of the solid-gas-liquid three-phase fluid in the riser 1, so as to meet the requirements of various conveying conditions. At the same time, a large amount of compressed air discharged from the backpressure cylinder 16 belongs to secondary energy. If it is discharged into the atmosphere, it will have a certain impact on environmental pollution and waste energy. In order to reduce environmental pollution and improve energy utilization efficiency, in this embodiment, a large amount of compressed air is dried and filtered and then transported to the inlet of the booster 23 for boosting, saving the operating cost of the air compressor 29 and reducing energy consumption, and realizing the secondary utilization of compressed air. In addition, a buffer is provided in the backpressure cylinder 16, and its function is to reduce the impact, vibration and wear of polymetallic nodules and seawater on the backpressure cylinder 16, play a buffering role, and reduce the crushing and pulverization of polymetallic nodule particles, which is beneficial to the sedimentation of the pulp in the storage tank 8 on the mining ship 30.

Claims

1. A pneumatic lifting system with a backpressure device, comprising a lifting pipe (1) and an air compressor (29), wherein the compressed air outlet of the air compressor (29) is connected to the lifting pipe (1) through a main gas transmission pipe (26), and is characterized in that, The outlet of the riser (1) is connected to a backpressure cylinder body (16). When the riser (1) discharges a solid-gas-liquid three-phase fluid into the backpressure cylinder body (16), the inside of the backpressure cylinder body (16) is maintained at a first pressure, and the first pressure is a positive pressure. A gas discharge port is provided on the backpressure cylinder body (16), and a first valve (19) is provided at the gas discharge port for adjusting the magnitude of the first pressure inside the backpressure cylinder body (16) to control the flow rate of the solid-gas-liquid three-phase fluid inside the riser (1).

2. The pneumatic lifting system according to claim 1, wherein One end of the first valve (19) is connected to the gas discharge port, and the other end of the first valve (19) is connected to the inlet of a booster (23) through a first gas pipeline (22). The outlet of the booster (23) is connected to the gas main pipeline (26) through a second gas pipeline (24), and a check valve (25) is provided on the second gas pipeline (24).

3. The pneumatic lifting system according to claim 2, characterized in that, One end of the first valve (19) is connected to the gas discharge port through a tee pipe (18), and a second valve (17) for communicating the backpressure cylinder body (16) with the outside is provided at the other end of the tee pipe (18).

4. The pneumatic lifting system according to claim 2, wherein, A cleaning device for cleaning the gas is provided on the first gas pipeline (22). The cleaning device sequentially includes a cold dryer (20) and a filter (21) according to the gas flow direction.

5. The pneumatic lifting system according to claim 1, characterized in that, A buffer for buffering the acting force of the solid-gas-liquid three-phase fluid discharged from the outlet of the riser (1) is provided in the backpressure cylinder body (16).

6. The pneumatic lifting system according to claim 5, wherein, The outlet of the riser (1) is located at the middle position of the backpressure cylinder body (16), and the buffer is arranged opposite to the outlet of the riser (1); the buffer includes a metal disc (14), wear-resistant rubber (15), a buffer spring (11), a connecting rod (12) and a guide cylinder (13). The wear-resistant rubber (15) is arranged on the surface of the metal disc (14) facing the outlet of the riser (1). The guide cylinder (13) is located on the outer wall of the backpressure cylinder body (16). One end of the metal disc (14) is connected to the connecting rod (12), and the other end of the connecting rod (12) is movably located in the guide cylinder (13). The buffer spring (11) is sleeved on the connecting rod (12) and is clamped between the metal disc (14) and the inner wall of the backpressure cylinder body (16).

7. The pneumatic lifting system according to claim 1, wherein The bottom outlet of the backpressure cylinder body (16) is connected to a storage bin (8) through a connecting pipe (10). The diameter of the connecting pipe (10) is 1.5 - 2 times the diameter of the riser (1). A seawater discharge pipe (3) is connected to the connecting pipe (10) through a third valve (9).

8. The pneumatic lifting system according to claim 7, wherein The top overflow outlet of the storage bin (8) is communicated with a secondary sedimentation tank (7). An overflow water pipe (4) is provided at the top of the secondary sedimentation tank (7). A seawater delivery pipe (6) is connected to the storage bin (8). The inlet end of the seawater delivery pipe (6) is located below the sea surface, and a submersible pump (5) is provided at the end.

9. The pneumatic lifting system according to claim 7, wherein When the riser (1) discharges the solid-gas-liquid three-phase fluid into the backpressure cylinder body (16), a liquid seal is provided in the backpressure cylinder body (16), and the liquid level height in the backpressure cylinder body (16) is kept the same as the liquid level height in the storage bin (8).

10. A pneumatic lifting method for submarine ore using the pneumatic lifting system according to any one of claims 1-9, characterized in that, Comprising the following steps: S1: Connect the backpressure cylinder body (16) to the outside world, and add seawater into the backpressure cylinder body (16). S2: Close the communication channel between the backpressure cylinder body (16) and the outside world, start the air compressor (29), and the compressed air compressed by the air compressor (29) is conveyed to the riser (1) through the main gas pipeline (26). Due to the injection of the compressed air, the submarine ore is sucked from the bottom of the riser (1) and lifted to the outlet of the riser (1), and is discharged into the backpressure cylinder body (16) as a solid-gas-liquid three-phase fluid. During the lifting process, a positive pressure is maintained in the backpressure cylinder body (16), and the flow rate of the solid-gas-liquid three-phase fluid in the riser (1) is adjusted by the opening and closing degree of the first valve (19). S3: After the lifting of the submarine ore is completed, turn off the air compressor (29), and connect the backpressure cylinder body (16) to the outside world to release the pressure inside it.

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