System and method for purifying kaolin through multi-field coupling magnetic separation

Abstract

The invention provides a system and a method for purifying kaolin through multi-field coupling magnetic separation, and relates to the technical field of magnetic separation, the system comprises a high-pressure high-gradient magnetic separator, an ore feeding, water feeding, gas feeding and homogenizing device, a supercharging device, a material receiving device, a material discharging container and a connecting pipeline; the high-pressure high-gradient magnetic separator comprises a magnet yoke, an exciting coil, a separation cavity and a magnetic medium; the connecting pipeline comprises a plurality of branches with high-pressure valves, and magnetic separation under the condition of a high-pressure field containing gas Van der Waals repulsive force, a liquid flowing force field and a high-gradient magnetic field coupled composite force field can be carried out in the separation cavity. The magnetic separator has the beneficial effects that traditional liquid-solid ore pulp in the magnetic separation cavity is converted into high-pressure gas-liquid-solid intersoluble ore pulp by introducing the high-pressure separation cavity, the adsorption effect between particles is weakened through Van der Waals repulsive force of gas in the high-pressure gas-liquid-solid intersoluble ore pulp, and the separation capacity of the magnetic separator on micro-fine-particle-level weakly-magnetic minerals is greatly improved; and efficient separation of strong-adsorption and easily-agglomerated particles in the ore pulp is promoted.

Description

Technical Field

[0001] The present invention relates to the field of magnetic separation technology, and in particular to a system and method for purifying kaolin by multi-field coupling magnetic separation. Background Art

[0002] High gradient magnetic separator is one of the common methods used to purify and remove iron or separate iron-containing minerals from non-metallic minerals, metal minerals and solid waste resources such as kaolin, hematite, and red mud. However, there are a large number of low-grade and difficult-to-purify mineral resources at home and abroad. The main feature of these minerals is that the strong adsorption force at the interface between non-magnetic minerals and magnetic minerals in the fine-grained mineral particles makes them easy to agglomerate when flowing in the magnetic separation cavity, resulting in a large amount of entrainment loss on the magnetic medium steel wool.

[0003] It is well known that the specific surface area, surface energy and activity of mineral particles will increase as the size of the mineral decreases. Especially when the mineral particles are smaller than the micron scale, the interfacial adsorption strength between the particles will be greatly enhanced, which will make it difficult to separate the magnetic particles during the magnetic separation process. During the magnetic separation process, the magnetic particles in the slurry are mainly affected by the adsorption force between the particles, the adsorption force between the particles and the magnetic medium, the fluid impact force of the slurry liquid and various surface tensions. Among them, the interfacial adsorption force between particles, such as van der Waals force, double-layer electrostatic force and hydrogen bond, especially the latter, will increase significantly as the size of the mineral particles decreases, resulting in serious agglomeration between the particles.

[0004] In recent years, new magnetic separators have been developed at home and abroad to solve the problem of magnetic separation of fine-grained mineral particles, such as electromagnetic slurry high gradient magnetic separator (patent CN210753198U), pulsating high gradient magnetic separator (patent CN1010832A, CN102614983A, CN112452535A, CN113976313A), ultrasonic assisted high gradient magnetic separator (patent CN202538920U), ultrasonic pulsating high gradient magnetic separator (patent CN116159668A), centrifugal high gradient magnetic separator (patent CN111558456A), etc. However, generally speaking, fine-grained impurities smaller than 2 microns have the characteristics of high surface energy and fast particle adsorption, and they often agglomerate within seconds in the slurry system. At present, the commonly used pulsating high-gradient magnetic separator applies a periodic pulsating vibration force field in the magnetic field through a pulsating mechanism to reduce the blockage problem of the magnetic medium and promote the separation of magnetic particles. Although it can reduce the agglomeration of large particles in the slurry and has achieved success in separating magnetic particles with a particle size greater than 400 mesh, it still cannot solve the problem of entrainment of fine particle impurities less than 2 microns. Similarly, although the ultrasonic magnetic separator can promote the dispersion of the slurry through ultrasonic dispersion pretreatment, it is still impossible to avoid the agglomeration problem of the slurry after it leaves the ultrasonic field and enters the magnetic separation cavity. In addition, patents CN 112439542 A and CN 112657671 A disclose high-temperature and high-pressure high-gradient magnetic separators for liquid-solid magnetic separation in the chemical industry. It is found that backwashing the magnetic medium with gas and / or flushing liquid can improve the removal rate of magnetic particles, and introducing an ultrasonic transmitter in the magnetic cavity can greatly improve the sorting efficiency. However, experiments have shown that the increase in pressure of the magnetic separator under high temperature and high pressure conditions cannot improve the separation efficiency.

[0005] Therefore, in general, the current high-gradient magnetic separators are still unable to solve the problem of separating fine-grained weakly magnetic minerals with strong adsorption behavior. It is urgent to solve the problem of entrainment of magnetic mineral particles and non-magnetic mineral particles during the magnetic separation process in order to achieve efficient separation. Summary of the invention

[0006] In view of this, in order to address the problems existing in conventional high gradient magnetic separators and to significantly improve the grade and recovery rate of magnetic concentrates containing fine-grained impurity minerals such as kaolin, especially the removal efficiency of impurity minerals with a size less than 2 microns, and reduce entrainment losses and blockage of magnetic media, an embodiment of the present invention provides a system and method for purifying kaolin by multi-field coupled magnetic separation.

[0007] The embodiment of the present invention provides a system for purifying kaolin by multi-field coupling magnetic separation, including a high-pressure high-gradient magnetic separator, a ore-feeding water-feeding gas-feeding homogenization device, a pressurizing device, a material receiving device, a material discharge container and a connecting pipeline;

[0008] The high-pressure high-gradient magnetic separator comprises a magnetic yoke, an exciting coil, a sorting cavity and a magnetic medium, wherein the magnetic yoke has an annular inner cavity, the exciting coil is embedded in the inner wall of the inner cavity of the magnetic yoke, the sorting cavity is arranged in the inner cavity, and the magnetic medium is arranged in the sorting cavity;

[0009] The connecting pipeline includes a plurality of branches with high-pressure valves, so that the boosting device is respectively connected to the ore-feeding, water-feeding, and gas-feeding homogenizing device and the material receiving device, and the ore-feeding, water-feeding, and gas-feeding homogenizing device, the material receiving device and the discharge container are connected to the sorting cavity, so that magnetic separation can be carried out in the sorting cavity under the conditions of a composite force field coupled with a high pressure field containing gas van der Waals repulsion, a liquid flow force field, and a high gradient magnetic field.

[0010] Furthermore, the upper end of the sorting cavity is provided with a feed pipe, and the lower end is provided with a discharge pipe, the feed pipe is provided with a second valve, the discharge pipe is connected to the discharge container, and the discharge pipe is provided with a fifth valve;

[0011] The connecting pipeline includes a first branch, a second branch, a third branch, a fourth branch and a fifth branch;

[0012] The booster device is provided with a tenth valve, one end of the first branch is connected to the tenth valve, and the other end is connected to the ore-feeding, water-feeding and gas-feeding homogenizing device, the first branch is provided with an eighth valve, the ore-feeding, water-feeding and gas-feeding homogenizing device is provided with a feed inlet, and the feed inlet is provided with a first valve;

[0013] One end of the second branch is connected to the tenth valve, and the other end is connected to the material receiving device, the second branch is provided with a ninth valve, the lower end of the material receiving device is provided with a discharge port, and the discharge port is provided with a twelfth valve;

[0014] One end of the third branch is connected to the ore-feeding, water-feeding and gas-feeding homogenizing device, and the other end is connected to the feed pipe, and a seventh valve is provided on the third branch;

[0015] One end of the fourth branch is connected to the material receiving device, and the other end is connected to the material discharge pipe, and a sixth valve is provided on the fourth branch;

[0016] One end of the fifth branch is connected to the discharge port, and the other end is connected to the feed pipe. The two ends of the fifth branch are respectively provided with an eleventh valve and a third valve. The fifth branch is also provided with a reflux device.

[0017] Furthermore, a slurry output pipe is provided at the bottom of the ore-feeding, water-feeding and gas-feeding homogenization device, a thirteenth valve is provided on the slurry output pipe, the discharge pipe is also connected to a fourteenth valve, and the thirteenth valve is connected to the fourteenth valve.

[0018] Furthermore, the branches are connected via three-way joints or four-way joints.

[0019] In addition, an embodiment of the present invention further provides a method for purifying kaolin by multi-field coupling magnetic separation, using the system for purifying kaolin by multi-field coupling magnetic separation, and comprising:

[0020] The high-pressure gas is introduced into the ore slurry in the ore-feeding, water-feeding and gas-feeding homogenizing device through the boosting device to form a high-pressure gas-liquid-solid miscible ore slurry; the high-pressure gas is introduced into the liquid in the sorting cavity through the boosting device to form a high-pressure gas-liquid miscible liquid; the excitation current is turned on to provide a background magnetic field for the magnetic yoke; the high-pressure gas-liquid-solid miscible ore slurry is input into the sorting cavity to perform magnetic separation under the conditions of a composite force field coupled with a high-pressure field containing gas van der Waals repulsion, a liquid flow force field, and a high-gradient magnetic field.

[0021] Further, the following steps are included:

[0022] S101, close all valves, open the first valve, input the ore pulp to be magnetically separated into the ore feeding, water feeding, and gas feeding homogenization device, then close the first valve, open the eighth valve and the tenth valve, and pass high-pressure gas into the ore feeding, water feeding, and gas feeding homogenization device through the booster device to obtain high-pressure gas-liquid-solid miscible ore pulp;

[0023] S102, opening the second valve, inputting the liquid into the separation chamber, then closing the second valve, opening the ninth valve, the eleventh valve, and the third valve, passing the high-pressure gas into the receiving device through the booster device and then inputting the high-pressure gas into the liquid in the separation chamber, to obtain a high-pressure gas-liquid miscible liquid;

[0024] S103, turning on the exciting current until the background magnetic induction intensity in the magnetic yoke reaches the required magnitude;

[0025] S104, close the third valve and the ninth valve, open the fourth valve, and pass the high-pressure gas-liquid-solid miscible slurry into the separation cavity through the booster device, so as to form a composite force field including a high pressure field of gas van der Waals repulsion, a liquid flow force field and a high gradient magnetic field coupled in the separation cavity;

[0026] S105, opening the sixth valve, the magnetic particles in the slurry are captured by the magnetic medium, and the non-magnetic particles flow into the receiving device.

[0027] Furthermore, it also includes:

[0028] S106, opening the eleventh valve, the third valve and the reflux device to allow the slurry to reflux into the separation chamber for cyclic magnetic separation until the required number of cycles is reached, then closing the eleventh valve, the sixth valve, the ninth valve and opening the twelfth valve to discharge the magnetically separated slurry through the discharge port.

[0029] Further, the following steps are included:

[0030] S201, close all valves, open the first valve, input the ore pulp to be magnetically separated into the ore feeding, water feeding, and gas feeding homogenization device, then close the first valve, open the eighth valve and the tenth valve, and pass high-pressure gas into the ore feeding, water feeding, and gas feeding homogenization device through the booster device to obtain high-pressure gas-liquid-solid miscible ore pulp;

[0031] S202, opening the second valve, inputting the liquid into the sorting chamber, and then closing the second valve;

[0032] S203, turning on the exciting current until the background magnetic induction intensity in the magnetic yoke reaches the required magnitude;

[0033] S204, closing the third valve and the ninth valve, opening the thirteenth valve and the fourteenth valve, and passing the high-pressure gas-liquid-solid miscible slurry into the separation cavity through the booster device, so as to form a composite force field in the separation cavity that includes a high-pressure field of gas van der Waals repulsion, a liquid flow force field, and a high-gradient magnetic field coupled;

[0034] S205, opening the second valve, the magnetic particles in the slurry are captured by the magnetic medium, and the non-magnetic particles are discharged from the feed pipe.

[0035] Furthermore, the separation cavity can withstand a pressure of 0.8 to 10 MPa after being sealed; the pressure of the high-pressure gas-liquid-solid miscible slurry is 0.8 to 10 MPa; and the high-pressure valve and pipeline can withstand a pressure of 0.8 to 10 MPa.

[0036] Furthermore, the high-pressure gas-liquid-solid solution slurry output by the mine water supply and gas supply device has a particle size range of 0 to 0.074 mm, a slurry concentration of 1 to 50 wt%, a slurry temperature of 0 to 80°C, and a slurry pressure of 0.8 to 10 MPa. The boosting device is a reactor, a booster pump or a high-pressure gas cylinder, the boosting mode is gas boosting, and the gas is various gases soluble in the slurry; the high-pressure gas-liquid-solid solution slurry is passed into the sorting cavity at a slurry flow rate of 0.1 to 100 cm / s, the magnetic yoke provides a background magnetic induction magnetic field strength of 0.5 to 6.0 T, and the magnetic medium is steel wool, a steel mesh or a composite medium mesh.

[0037] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention are:

[0038] 1. The system and method of purifying kaolin by multi-field coupling magnetic separation of the present invention, by introducing a high-pressure separation cavity to convert the traditional liquid-solid slurry in the magnetic separation cavity into a high-pressure gas-liquid-solid solution slurry, and utilizing the van der Waals repulsion of the gas inside it to weaken the adsorption between particles, and by controlling the slurry pressure, flow rate, and temperature, magnetic separation can be achieved under the conditions of a composite force field including a high pressure field containing gas van der Waals repulsion, a liquid flow field, and a high gradient magnetic field coupling. Among them, the multi-field coupling of the repulsion between solid particles inside the high-pressure gas-liquid-solid solution slurry and the high gradient magnetic field force greatly improves the separation ability of the magnetic separator for fine-grained weakly magnetic minerals, and promotes the efficient separation of strongly adsorbed and easily agglomerated particles inside the slurry.

[0039] 2. The multi-field coupled magnetic separation system for purifying kaolin of the present invention has three modes: single high-pressure coupled magnetic separation, cyclic high-pressure coupled magnetic separation and high-pressure pretreatment coupled magnetic separation. It can carry out magnetic separation research in complex fluid environments and realize multi-field coupling of van der Waals repulsion, inertial force, fluid drag and high-gradient magnetic field force in gas-liquid-solid mixed slurry under high-pressure conditions, which is helpful for the optimization and innovation of multi-field coupled magnetic separation technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic diagram of a system for purifying kaolin by multi-field coupling magnetic separation of the present invention;

[0041] Figure 2 yes Figure 1 Schematic diagram of a medium-high pressure high gradient magnetic separator;

[0042] In the figure: 1. high pressure and high gradient magnetic separator; 2. ore feeding, water feeding and gas feeding homogenizing device; 3. booster device; 4. material receiving device; 5. discharge container; 6. first branch; 7. second branch; 8. third branch; 9. fourth branch; 10. fifth branch; 11. feed pipe; 12. discharge pipe; 13. feed port; 14. first valve; 15. tenth valve; 16. eighth valve; 17. ninth valve; 18. discharge port; 19. twelfth valve; 20. eleventh valve; 21. reflux device; 22. slurry output pipe; 23. thirteenth valve; 24. seventh valve; 25. sixth valve; 26. fifth valve; 27. fourteenth valve; 28. fourth valve; 29. ​​second valve; 30. third valve; 31. yoke; 32. excitation coil; 33. separation cavity; 34. magnetic medium. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the present invention clearer, the following will further describe the embodiments of the present invention in conjunction with the accompanying drawings. The following is a preferred embodiment of the present invention, which is intended to provide a basic understanding of the present invention, but is not intended to confirm the key or decisive elements of the present invention or to limit the scope of protection.

[0044] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0045] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0046] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in the subsequent drawings. At the same time, it should be understood that for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0047] In the description of the present invention, it should be noted that the circuits, electronic components and modules involved in the present invention are all prior art and can be fully implemented by those skilled in the art without further elaboration.

[0048] It should be further explained that, unless otherwise clearly specified and limited, the terms "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0049] Please refer to Figure 1 The embodiment of the present invention provides a system for purifying kaolin by multi-field coupling magnetic separation, including a high-pressure high-gradient magnetic separator 1, a ore-feeding, water-feeding and gas-feeding homogenization device 2, a pressurizing device 3, a material receiving device 4, a discharge container 5 and a connecting pipeline.

[0050] Please refer to Figure 2 The high-pressure high-gradient magnetic separator 1 includes a magnetic yoke 31, an exciting coil 32, a separation cavity 33 and a magnetic medium 34. The magnetic yoke 31 can generally be set to be annular or disc-shaped, with an annular inner cavity. The exciting coil 32 is embedded in the inner wall of the inner cavity of the magnetic yoke 31.

[0051] The sorting cavity 33 is arranged in the inner cavity, and the magnetic medium 34 is arranged in the sorting cavity 33. As described in this embodiment, the sorting cavity 33 is a cylinder with a closed lower end and a quick-opening flange at the upper end, and the magnetic medium 34 is horizontally arranged in the middle of the sorting cavity 33, and the magnetic medium 34 and the sorting cavity 33 are detachably connected.

[0052] The connecting pipeline includes multiple branches with high-pressure valves, so that the boosting device 3 is respectively connected to the ore-feeding, water-feeding, gas-feeding and homogenizing device 2 and the material receiving device 4, and the ore-feeding, water-feeding, gas-feeding and homogenizing device 2, the material receiving device 4 and the discharge container 5 are connected to the sorting cavity 33.

[0053] As in this embodiment, the connecting pipeline includes a first branch 6 , a second branch 7 , a third branch 8 , a fourth branch 9 and a fifth branch 10 .

[0054] The sorting cavity 33 is provided with a feed pipe 11 at the upper end and a discharge pipe 12 at the lower end. The feed pipe 11 is provided with a second valve 29. The discharge pipe 12 is connected to the discharge container 5 and provided with a fifth valve 26.

[0055] The booster device 3 is provided with a tenth valve 15, one end of the first branch 6 is connected to the tenth valve 15, and the other end is connected to the ore-feeding, water-feeding and gas-feeding homogenizing device 2, the first branch 6 is provided with an eighth valve 16, the ore-feeding, water-feeding and gas-feeding homogenizing device 2 is provided with a feed port 13, and the feed port 13 is provided with a first valve 14;

[0056] One end of the second branch 7 is connected to the tenth valve 15, and the other end is connected to the material receiving device 4. The second branch 7 is provided with a ninth valve 17. The lower end of the material receiving device 4 is provided with a discharge port 18, and the discharge port 18 is provided with a twelfth valve 19.

[0057] One end of the third branch 8 is connected to the ore-feeding, water-feeding and gas-feeding homogenization device 2, and the other end is connected to the feed pipe 11. A seventh valve 24 is provided on the third branch 8;

[0058] One end of the fourth branch 9 is connected to the material receiving device 4, and the other end is connected to the discharge pipe 12, and a sixth valve 25 is provided on the fourth branch 9;

[0059] One end of the fifth branch 10 is connected to the discharge port 18 , and the other end is connected to the feed pipe 11 . An eleventh valve 20 and a third valve 30 are respectively disposed at both ends of the fifth branch 10 . A reflux device 21 is also disposed on the fifth branch 10 .

[0060] Furthermore, a slurry output pipe 22 is provided at the bottom of the ore-feeding, water-feeding and gas-feeding homogenization device 2, a thirteenth valve 23 is provided on the slurry output pipe 22, the discharge pipe 12 is also connected to a fourteenth valve 27, and the thirteenth valve 23 is connected to the fourteenth valve 27 (not shown in the figure).

[0061] The branches are connected via three-way joints or four-way joints, which simplifies the arrangement and connection between the branches.

[0062] It should be noted that in this embodiment, each branch circuit is operated under high pressure, so each valve needs to be a high pressure valve, and various types of high pressure valves can be flexibly selected according to the actual application scenario. For example, the working pressure of each branch circuit in this embodiment is 0.8-10Mpa, so the pressure that each valve can withstand is 0.8-10Mpa. Similarly, the reflux device 21 selects a high pressure resistant reflux pump.

[0063] Through the cooperation of the ore-feeding, water-feeding and gas-feeding homogenizing device 2 and the pressurizing device 3, magnetic separation can be carried out in the separation cavity 33 under the conditions of a composite force field including a high pressure field of gas van der Waals repulsion, a liquid flow field and a high gradient magnetic field coupling.

[0064] In addition, please refer to Figure 1 The embodiment of the present invention further provides a method for purifying kaolin by multi-field coupling magnetic separation, using the system for purifying kaolin by multi-field coupling magnetic separation, and comprising:

[0065] The high-pressure gas is introduced into the ore slurry in the ore-feeding, water-feeding and gas-feeding homogenization device 2 through the booster device 3 to form a high-pressure gas-liquid-solid miscible ore slurry; the high-pressure gas is introduced into the liquid in the sorting cavity 33 through the booster device 3 to form a high-pressure gas-liquid miscible liquid; the excitation current is turned on to provide a background magnetic field for the magnetic yoke 31; the high-pressure gas-liquid-solid miscible ore slurry is input into the sorting cavity 33, and magnetic separation is carried out under the composite force field conditions of high pressure field containing gas van der Waals repulsion, liquid flow force field, and high gradient magnetic field coupling.

[0066] According to the above-mentioned multi-field coupled magnetic separation method for purifying kaolin, the working modes of a multi-field coupled magnetic separation system for purifying kaolin of the present invention include single high-pressure coupled magnetic separation, cyclic high-pressure coupled magnetic separation and high-pressure pretreatment coupled magnetic separation, which are specifically as follows:

[0067] Single high voltage coupled magnetic separation:

[0068] S101, close all valves, open the first valve 14, input the ore pulp to be magnetically separated into the ore feeding, water feeding, gas feeding and homogenizing device 2, then close the first valve 14, open the eighth valve 16 and the tenth valve 15, and pass high-pressure gas into the ore feeding, water feeding, gas feeding and homogenizing device 2 through the booster device 3 to obtain high-pressure gas-liquid-solid miscible ore pulp;

[0069] Here, when the ore pulp needs to be homogenized, the high shear stirring component inside the ore-feeding, water-feeding and air-feeding homogenization device 2 is used to homogenize the ore pulp to meet the homogenization requirements.

[0070] S102, opening the second valve 29, inputting the liquid into the separation cavity 33, then closing the second valve 29, opening the ninth valve 17, the eleventh valve 20, and the third valve 30, passing the high-pressure gas into the receiving device 4 through the booster device 3 and then inputting the high-pressure gas into the liquid in the separation cavity 33, to obtain a high-pressure gas-liquid miscible liquid;

[0071] S103, turning on the exciting current of the exciting coil 32 until the background magnetic induction intensity in the magnetic yoke 31 reaches the required magnitude;

[0072] S104, close the third valve 30 and the ninth valve 17, open the fourth valve 28, and pass the high-pressure gas-liquid-solid miscible slurry into the separation cavity 33 through the booster device 3, so as to form a composite force field in the separation cavity 33 that includes a high-pressure field of gas van der Waals repulsion, a liquid flow force field, and a high-gradient magnetic field coupled;

[0073] S105 , opening the sixth valve 25 , the magnetic particles in the slurry are captured by the magnetic medium 34 , and the non-magnetic particles flow into the receiving device 4 .

[0074] After the ore pulp in the separation chamber 33 is emptied, the sixth valve 25 and the ninth valve 17 are closed, and the twelfth valve 19 is opened to discharge the ore pulp through the receiving device 4. After the receiving device 4 has finished discharging the material, the third valve 30 is closed, the excitation current of the excitation coil 32 is turned off, and the fifth valve 26 is opened, so that the magnetic particles captured by the magnetic medium 34 flow into the discharge container 5 to form a magnetic product.

[0075] When the magnetic particles are discharged, the second valve 29 is opened to allow high-pressure water or gas to be introduced to flush the magnetic medium 34, and then the next step of magnetic separation is entered.

[0076] After multiple magnetic separations, when the magnetic medium 34 is clogged, the second valve 29, the third valve 30, the third valve 30, the fifth valve 26 can be closed and the sixth valve 25 can be opened to open the separation cavity 33 and take out the magnetic medium 34 for comprehensive cleaning.

[0077] Cyclic high voltage coupled magnetic separation mode

[0078] Different from the single high-voltage coupled magnetic separation mode, after step S105, step S106 is performed: the eleventh valve 20, the third valve 30 and the reflux device 21 are opened to allow the slurry to reflux into the separation chamber 33 for cyclic magnetic separation until the required number of cycles is reached, then the eleventh valve 20, the sixth valve 25, the ninth valve 17 are closed and the twelfth valve 19 is opened to discharge the magnetically separated slurry through the discharge port 18.

[0079] High-voltage pretreatment coupled with magnetic separation in three modes

[0080] S201, close all valves, open the first valve 14, input the ore pulp to be magnetically separated into the ore feeding, water supply and gas supply homogenization device 2, then close the first valve 14, open the eighth valve 16 and the tenth valve 15, and pass high-pressure gas into the ore feeding, water supply and gas supply homogenization device 2 through the booster device 3 to obtain high-pressure gas-liquid-solid miscible ore pulp.

[0081] Here, when the ore pulp needs to be homogenized, the high shear stirring component inside the ore-feeding, water-feeding and air-feeding homogenization device 2 is used to homogenize the ore pulp to meet the homogenization requirements.

[0082] S202, opening the second valve 29, inputting the liquid into the sorting cavity 33, and then closing the second valve 29;

[0083] S203, turning on the exciting current of the exciting coil 32 until the background magnetic induction intensity in the magnetic yoke 31 reaches the required magnitude;

[0084] S204, close the third valve 30 and the ninth valve 17, open the thirteenth valve 23 and the fourteenth valve 27, and pass the high-pressure gas-liquid-solid miscible slurry into the separation cavity 33 through the booster device 3, so as to form a composite force field in the separation cavity 33 that includes a high pressure field of gas van der Waals repulsion, a liquid flow force field and a high gradient magnetic field coupled;

[0085] S205 , opening the second valve 29 , the magnetic particles in the slurry are captured by the magnetic medium 34 , and the non-magnetic particles are discharged from the feed pipe 11 .

[0086] After the slurry in the sorting cavity 33 is emptied, the excitation current of the excitation coil 32 is turned off, the thirteenth valve 23 and the fourteenth valve 27 are closed, the fifth valve 26 is opened, and the second valve 29 is opened to pass high-pressure water or gas to flush the magnetic medium 34 until the discharged liquid is clear water, and the magnetic product captured by the magnetic medium 34 flows into the discharge container 5 to form a magnetic product, and then enters the next stage of magnetic separation. After multiple magnetic separations, when the magnetic medium is blocked, the second valve 29, the third valve 30, the third valve 30, the fifth valve 26 can be closed and the sixth valve 25 can be opened to empty the high-pressure gas inside the sorting cavity 33, open the sorting cavity 33, and take out the magnetic medium 34 for comprehensive cleaning.

[0087] It should be noted that the pressure of the high-pressure gas-liquid-solid solution slurry in this embodiment is 0.8-10 MPa, so the separation cavity 33 can withstand a pressure of 0.8-10 MPa after being sealed; the high-pressure valve and pipeline can withstand a pressure of 0.8-10 MPa. In addition, the high-pressure gas-liquid-solid solution slurry output by the mine water supply and gas supply device has a particle size range of 0-0.074mm, a slurry concentration of 1-50wt%, a slurry temperature of 0-80°C, and a slurry pressure of 0.8-10Mpa. The booster device 3 is a reactor, a booster pump or a high-pressure gas cylinder, and the boosting mode is gas boosting. The gas is various gases soluble in the slurry; the liquid can be selected as water, and the slurry flow rate of the high-pressure gas-liquid-solid solution slurry passed into the sorting cavity 33 is 0.1-100cm / s. The magnetic yoke 31 provides a background magnetic induction magnetic field strength of 0.5-6.0T, and the magnetic medium 34 is stainless steel wool, steel mesh or composite medium mesh.

[0088] In addition, the present invention also conducted tests on the above-mentioned multi-field coupled magnetic separation system for purifying kaolin as follows:

[0089] Example 1 (single high voltage coupled magnetic separation mode)

[0090] Step 1: Kaolin removal

[0091] A low-grade Beihai kaolin ore was ball-milled into powder and passed through a 325-mesh sieve to obtain impurity-free kaolin with a kaolinite purity of 80% and an iron content of 1.8wt%.

[0092] Step 2: High-pressure homogenization

[0093] A kaolin slurry with a slurry concentration of 10wt% is configured as the feed slurry, which is input into the ore-feeding, water-feeding and gas-feeding homogenization device. High-pressure gas is introduced into the ore-feeding, water-feeding and gas-feeding homogenization device through a booster device. High-shear stirring is performed at a pressure of 2.0Mpa and a temperature of 60°C for 15 minutes to obtain a high-pressure gas-liquid-solid miscible solution slurry.

[0094] Step 3: High-voltage magnetic separation

[0095] Water and high-pressure gas are introduced into the sorting chamber of the high-pressure high-gradient magnetic separator in sequence through a booster device. After the water level and pressure are reached, the excitation current of the excitation coil is turned on until the background magnetic induction intensity in the magnetic yoke reaches 2.0T. The high-pressure gas-liquid-solid miscible slurry is introduced into the sorting chamber for sorting. The slurry flow rate is 1cm / s. The magnetic particles in the material are captured by the magnetic medium, and the non-magnetic particles flow into the receiving device and are discharged through the discharge port to obtain non-magnetic material slurry. Then, the excitation current of the excitation coil is turned off until the background magnetic induction intensity in the magnetic yoke reaches the required size, and the magnetic product captured by the magnetic medium flows into the discharge container, and high-pressure water or gas is introduced to flush the magnetic medium to obtain magnetic material slurry.

[0096] Step 4: Single magnetic separation cumulative test

[0097] Using the non-magnetic material slurry as the feed slurry, repeat steps 2 to 3 for a total of 4 cycles to obtain the final non-magnetic material slurry.

[0098] Step 5: Grading

[0099] The non-magnetic material slurry is diluted 2 to 20 times, stirred under high shear for 1 hour, and then allowed to stand for 3 to 12 hours. The upper half of the slurry is centrifuged and dried to obtain high-purity kaolin.

[0100] Example 2 (Cyclic High Voltage Coupling Magnetic Separation Mode)

[0101] Step 1: Kaolin removal

[0102] A low-grade Beihai kaolin ore was ball-milled into powder and passed through a 325-mesh sieve to obtain impurity-free kaolin with a kaolinite purity of 80% and an iron content of 1.8wt%.

[0103] Step 2: High-pressure homogenization

[0104] A kaolin slurry with a slurry concentration of 10wt% is configured as the feed slurry, which is input into the ore-feeding, water-feeding and gas-feeding homogenization device. High-pressure gas is introduced into the ore-feeding, water-feeding and gas-feeding homogenization device through a booster device. High-shear stirring is performed at a pressure of 2.0Mpa and a temperature of 60°C for 15 minutes to obtain a high-pressure gas-liquid-solid miscible solution slurry.

[0105] Step 3: High-pressure cyclic magnetic separation

[0106] Water and high-pressure gas are introduced into the sorting chamber of the high-pressure high-gradient magnetic separator in sequence through the booster device. After the water level and pressure are reached, the excitation current of the excitation coil is turned on until the background magnetic induction intensity in the magnetic yoke reaches 2.0T. The high-pressure gas-liquid-solid miscible slurry is introduced into the sorting chamber for sorting. The slurry flow rate is 3.0cm / s. The magnetic particles in the material are captured by the magnetic medium, and the non-magnetic particles enter the magnetic separator again through the reflux device for sorting. The pressure is maintained and the cycle is repeated 3 times. The non-magnetic particles flow into the receiving device and are discharged through the discharge port to obtain non-magnetic material slurry. Then, the excitation current of the excitation coil is turned off until the background magnetic induction intensity in the magnetic yoke reaches the required size, and the magnetic product captured by the magnetic medium flows into the discharge container, and high-pressure water or gas is introduced to flush the magnetic medium to obtain magnetic material slurry.

[0107] Step 4: Single magnetic separation cumulative test

[0108] Using the non-magnetic material slurry as the feed slurry, repeat steps 2 to 3 for a total of 4 cycles to obtain the final non-magnetic material slurry.

[0109] Step 5: Grading

[0110] The non-magnetic material slurry is diluted 2 to 20 times, stirred under high shear for 1 hour, and then allowed to stand for 3 to 12 hours. The upper half of the slurry is centrifuged and dried to obtain high-purity kaolin.

[0111] Example 3 (High-pressure pretreatment coupled with magnetic separation mode)

[0112] Step 1: Kaolin removal

[0113] A low-grade Beihai kaolin ore was ball-milled into powder and passed through a 325-mesh sieve to obtain impurity-free kaolin with a kaolinite purity of 80% and an iron content of 1.8wt%.

[0114] Step 2: High-pressure homogenization

[0115] A kaolin slurry with a slurry concentration of 10wt% is configured as the feed slurry, which is input into the ore-feeding, water-feeding and gas-feeding homogenization device. High-pressure gas is introduced into the ore-feeding, water-feeding and gas-feeding homogenization device through a booster device. High-shear stirring is performed for 15 minutes at a pressure of 2.0Mpa and a temperature of 30°C to obtain a high-pressure gas-liquid-solid miscible solution slurry.

[0116] Step 3: High-pressure pretreatment magnetic separation

[0117] Water is introduced into the sorting chamber of the high-pressure high-gradient magnetic separator through a booster device. When the water level is reached, the excitation current of the excitation coil is turned on until the background magnetic induction intensity in the magnetic yoke reaches 2.0T. The high-pressure gas-liquid-solid miscible slurry is introduced into the sorting chamber for sorting. The slurry flow rate is 1cm / s. The magnetic particles in the material are captured by the magnetic medium, and the non-magnetic particles are discharged through the discharge port to obtain non-magnetic material slurry. Then, the excitation current of the excitation coil is turned off until the background magnetic induction intensity in the magnetic yoke reaches the required size. The magnetic product captured by the magnetic medium flows into the discharge container, and high-pressure water or gas is introduced to flush the magnetic medium to obtain magnetic material slurry.

[0118] Step 4: Single magnetic separation cumulative test

[0119] Using the non-magnetic material slurry as the feed slurry, repeat steps 2 to 3 for a total of 4 cycles to obtain the final non-magnetic material slurry.

[0120] Step 4: Grading

[0121] The non-magnetic material slurry is diluted 2 to 20 times, stirred under high shear for 1 hour, and then allowed to stand for 3 to 12 hours. The upper half of the slurry is centrifuged and dried to obtain high-purity kaolin.

[0122] Example 4 (Cyclic High Voltage Coupling Magnetic Separation Mode)

[0123] Step 1: Kaolin removal

[0124] A low-grade Beihai kaolin ore was ball-milled into powder and passed through a 325-mesh sieve to obtain impurity-free kaolin with a kaolinite purity of 80% and an iron content of 1.8wt%.

[0125] Step 2: High-pressure homogenization

[0126] A kaolin slurry with a slurry concentration of 10wt% is configured as the feed slurry, which is input into the ore-feeding, water-feeding and gas-feeding homogenization device. High-pressure gas is introduced into the ore-feeding, water-feeding and gas-feeding homogenization device through a booster device. High-shear stirring is performed for 15 minutes at a pressure of 5.0Mpa and a temperature of 80°C to obtain a high-pressure gas-liquid-solid miscible solution slurry.

[0127] Step 3: High-pressure cyclic magnetic separation

[0128] Water and high-pressure gas are introduced into the sorting chamber of the high-pressure high-gradient magnetic separator in sequence through the booster device. After the water level and pressure are reached, the excitation current of the excitation coil is turned on until the background magnetic induction intensity in the magnetic yoke reaches 2.0T. The high-pressure gas-liquid-solid miscible slurry is introduced into the sorting chamber for sorting. The slurry flow rate is 3.0cm / s. The magnetic particles in the material are captured by the magnetic medium, and the non-magnetic particles enter the magnetic separator again through the reflux device for sorting. The pressure is maintained and the cycle is repeated 3 times. The non-magnetic particles flow into the receiving device and are discharged through the discharge port to obtain non-magnetic material slurry. Then, the excitation current of the excitation coil is turned off until the background magnetic induction intensity in the magnetic yoke reaches the required size, and the magnetic product captured by the magnetic medium flows into the discharge container, and high-pressure water or gas is introduced to flush the magnetic medium to obtain magnetic material slurry.

[0129] Step 4: Single magnetic separation cumulative test

[0130] Using the non-magnetic material slurry as the feed slurry, repeat steps 2 to 3 for a total of 2 cycles to obtain the final non-magnetic material slurry.

[0131] Step 5: Grading

[0132] The non-magnetic material slurry is diluted 2 to 20 times, stirred under high shear for 1 hour, and then allowed to stand for 3 to 12 hours. The upper half of the slurry is centrifuged and dried to obtain high-purity kaolin.

[0133] Comparative Example 1 (Electromagnetic slurry high gradient magnetic separator 4 times)

[0134] S1. Step 1: Kaolin impurity removal

[0135] A low-grade Beihai kaolin ore was ball-milled into powder and passed through a 325-mesh sieve to obtain impurity-free kaolin with a kaolinite purity of 80% and an iron content of 1.8wt%.

[0136] Step 2: Homogenization

[0137] A kaolin slurry with a slurry concentration of 10 wt% was prepared as the feed slurry, and vigorously stirred for 15 minutes using a high-speed disperser at a temperature of 30° C. to obtain a homogenized slurry.

[0138] Step 3: Magnetic Separation

[0139] Water is passed into the separation chamber of the electromagnetic slurry high gradient magnetic separator. When the water level is reached, the excitation current of the excitation coil is turned on until the background magnetic induction intensity in the magnetic yoke reaches 2.0T. The homogenized slurry is passed into the separation chamber for sorting. The slurry flow rate is 1cm / s. The magnetic particles in the material are captured by the magnetic medium, and the non-magnetic particles are discharged through the discharge port to obtain non-magnetic material slurry. Then, the excitation current of the excitation coil is turned off until the background magnetic induction intensity in the magnetic yoke reaches the required size. The magnetic product captured by the magnetic medium flows into the discharge container, and high-pressure water or gas is passed to flush the magnetic medium to obtain magnetic material slurry.

[0140] Step 4: Single magnetic separation cumulative test

[0141] Using the non-magnetic material slurry as the feed slurry, repeat steps 2 to 3 for a total of 4 cycles to obtain the final non-magnetic material slurry.

[0142] Step 5: Grading

[0143] The non-magnetic material slurry is diluted 2 to 20 times, stirred under high shear for 1 hour, and then allowed to stand for 3 to 12 hours. The upper half of the slurry is centrifuged and dried to obtain high-purity kaolin.

[0144] Comparative Example 2 (pulsating high gradient magnetic separation 4 times)

[0145] Step 1: Kaolin removal

[0146] A low-grade Beihai kaolin ore was ball-milled into powder and passed through a 325-mesh sieve to obtain impurity-free kaolin with a kaolinite purity of 80% and an iron content of 1.8wt%.

[0147] Step 2: Homogenization

[0148] A kaolin slurry with a slurry concentration of 10 wt% was prepared as the feed slurry, and vigorously stirred for 15 minutes using a high-speed disperser at a temperature of 30° C. to obtain a homogenized slurry.

[0149] Step 3: Magnetic Separation

[0150] Pass water into the separation chamber of the pulsating high-gradient magnetic separator. When the water level is reached, turn on the excitation current of the excitation coil until the background magnetic induction intensity in the magnetic yoke reaches 1.8T, and then turn on the pulsation device. Pass the homogenized slurry into the separation chamber for sorting. The slurry flow rate is 1cm / s. The magnetic particles in the material are captured by the magnetic medium, and the non-magnetic particles are discharged through the discharge port to obtain non-magnetic material slurry. Then, turn off the excitation current of the excitation coil until the background magnetic induction intensity in the magnetic yoke reaches the required size, and the magnetic product captured by the magnetic medium flows into the discharge container, and high-pressure water or gas is passed to flush the magnetic medium to obtain magnetic material slurry.

[0151] Step 4: Single magnetic separation cumulative test

[0152] Using the non-magnetic material slurry as the feed slurry, repeat steps 2 to 3 for a total of 4 cycles to obtain the final non-magnetic material slurry.

[0153] Step 5: Grading

[0154] The non-magnetic material slurry is diluted 2 to 20 times, stirred under high shear for 1 hour, and then allowed to stand for 3 to 12 hours. The upper half of the slurry is centrifuged and dried to obtain high-purity kaolin.

[0155] Comparative Example 3 (Electromagnetic slurry high gradient magnetic separator 2 times)

[0156] S1. Step 1: Kaolin impurity removal

[0157] A low-grade Beihai kaolin ore was ball-milled into powder and passed through a 325-mesh sieve to obtain impurity-free kaolin with a kaolinite purity of 80% and an iron content of 1.8wt%.

[0158] Step 2: Homogenization

[0159] A kaolin slurry with a slurry concentration of 10 wt% was prepared as the feed slurry, and vigorously stirred for 15 minutes using a high-speed disperser at a temperature of 30° C. to obtain a homogenized slurry.

[0160] Step 3: Magnetic Separation

[0161] Water is passed into the separation chamber of the electromagnetic slurry high gradient magnetic separator. When the water level is reached, the excitation current of the excitation coil is turned on until the background magnetic induction intensity in the magnetic yoke reaches 2.0T. The homogenized slurry is passed into the separation chamber for sorting. The slurry flow rate is 1cm / s. The magnetic particles in the material are captured by the magnetic medium, and the non-magnetic particles are discharged through the discharge port to obtain non-magnetic material slurry. Then, the excitation current of the excitation coil is turned off until the background magnetic induction intensity in the magnetic yoke reaches the required size. The magnetic product captured by the magnetic medium flows into the discharge container, and high-pressure water or gas is passed to flush the magnetic medium to obtain magnetic material slurry.

[0162] Step 4: Single magnetic separation cumulative test

[0163] Using the non-magnetic material slurry as the feed slurry, repeat steps 2 to 3 for a total of 2 cycles to obtain the final non-magnetic material slurry.

[0164] Step 5: Grading

[0165] The non-magnetic material slurry is diluted 2 to 20 times, stirred under high shear for 1 hour, and then allowed to stand for 3 to 12 hours. The upper half of the slurry is centrifuged and dried to obtain high-purity kaolin.

[0166] Result detection and analysis

[0167] The yield and recovery rate of the non-magnetic material after magnetic separation and the purity of the kaolin after classification in Examples 1 to 4 and Comparative Examples 1 to 3 are shown in Table 1.

[0168] It can be seen from the data of Comparative Examples 1 and 2 that after 4 magnetic separations, the separation and purification efficiency of the electromagnetic slurry machine and the pulsating high gradient magnetic separator is not ideal. The non-magnetic mineral particles on the magnetic medium steel wool in the magnetic separation process are seriously entrained, resulting in low yield, recovery rate and kaolin purity of non-magnetic substances. Although the content of the electromagnetic slurry machine is slightly higher than that of the pulsating high gradient magnetic separator, the yield is slightly lower. In contrast, the yield, recovery rate and kaolin purity of non-magnetic substances in Examples 1 to 3 of the technology of the present invention have been greatly improved. Among them, the kaolin recovery rate can reach 69.5% and the purity can reach 98.0% after 2 magnetic separations in a single high-pressure coupled magnetic separation mode, and the kaolin recovery rate can reach 74.1% and the purity can reach 98.5% after 2 magnetic separations in a cyclic high-pressure coupled magnetic separation mode, and the kaolin recovery rate can reach 65.4% and the purity can reach 98.0% after 2 magnetic separations in a high-pressure pretreatment coupled magnetic separation mode. It can be seen from the data of Example 4 and Comparative Example 3 that, compared with the electromagnetic slurry high gradient magnetic separator, when the number of magnetic separations is 2, under the same magnetic separation time, the kaolin recovery rate and purity of the technology of the present invention are greatly improved, especially the recovery rate, which can be increased by about twice.

[0169] Table 1 shows the yield, recovery, iron content and kaolin purity of various embodiments and comparative examples.

[0170] sample Yield / % Recovery rate / % Iron content / % Kaolin purity / % Example 1 25 29.4 0.34 98.0 Example 2 29 34.1 0.25 98.5 Example 3 23 27.1 0.43 98.0 Example 4 60 70.5 0.52 96.5 Comparative Example 1 11 12.8 0.64 94.0 Comparative Example 2 15 16.4 0.92 92.0 Comparative Example 3 31 34.6 0.83 92.5

[0171] The present invention discloses a system and method for purifying kaolin by multi-field coupled magnetic separation. The composite force field containing the van der Waals repulsive force of high-pressure gas in the separation chamber can greatly reduce the agglomeration and entrainment of fine-grained magnetic particles and non-magnetic particles near the magnetic medium, thereby improving the magnetic medium's ability to capture magnetic substances and improving the grade and recovery rate of the product.

[0172] In this article, the directional words such as front, back, top, and bottom involved are defined by the positions of the parts in the drawings and the positions of the parts relative to each other, just for the sake of clarity and convenience in expressing the technical solution. It should be understood that they are relative concepts and can change accordingly according to different ways of use and placement, and the use of the directional words should not limit the scope of protection claimed in this application.

[0173] In the absence of conflict, the above embodiments and features in the embodiments may be combined with each other. The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A system for purifying kaolin by multi-field coupling magnetic separation, characterized in that: include: High-pressure high-gradient magnetic separator, ore-feeding, water-feeding and gas-feeding homogenization device, booster device, material receiving device, material discharge container and connecting pipelines; The high-pressure high-gradient magnetic separator comprises a magnetic yoke, an exciting coil, a sorting cavity and a magnetic medium, wherein the magnetic yoke has an annular inner cavity, the exciting coil is embedded in the inner wall of the inner cavity of the magnetic yoke, the sorting cavity is arranged in the inner cavity, and the magnetic medium is arranged in the sorting cavity; The connecting pipeline includes a plurality of branches with high-pressure valves, so that the boosting device is respectively connected to the ore-feeding, water-feeding, and gas-feeding homogenizing device and the material receiving device, and the ore-feeding, water-feeding, and gas-feeding homogenizing device, the material receiving device and the discharge container are connected to the sorting cavity, so that magnetic separation can be carried out in the sorting cavity under the conditions of a composite force field coupled with a high pressure field containing gas van der Waals repulsion, a liquid flow force field, and a high gradient magnetic field.

2. A system for purifying kaolin by multi-field coupling magnetic separation as claimed in claim 1, characterized in that: The upper end of the sorting cavity is provided with a feed pipe, and the lower end is provided with a discharge pipe, the feed pipe is provided with a second valve, the discharge pipe is connected to the discharge container, and the discharge pipe is provided with a fifth valve; The connecting pipeline includes a first branch, a second branch, a third branch, a fourth branch and a fifth branch; The booster device is provided with a tenth valve, one end of the first branch is connected to the tenth valve, and the other end is connected to the ore-feeding, water-feeding and gas-feeding homogenizing device, the first branch is provided with an eighth valve, the ore-feeding, water-feeding and gas-feeding homogenizing device is provided with a feed inlet, and the feed inlet is provided with a first valve; One end of the second branch is connected to the tenth valve, and the other end is connected to the material receiving device, the second branch is provided with a ninth valve, the lower end of the material receiving device is provided with a discharge port, and the discharge port is provided with a twelfth valve; One end of the third branch is connected to the ore-feeding, water-feeding and gas-feeding homogenizing device, and the other end is connected to the feed pipe, and a seventh valve is provided on the third branch; One end of the fourth branch is connected to the material receiving device, and the other end is connected to the material discharge pipe, and a sixth valve is provided on the fourth branch; One end of the fifth branch is connected to the discharge port, and the other end is connected to the feed pipe. The two ends of the fifth branch are respectively provided with an eleventh valve and a third valve. The fifth branch is also provided with a reflux device.

3. A system for purifying kaolin by multi-field coupling magnetic separation as claimed in claim 2, characterized in that: A slurry output pipe is also provided at the bottom of the ore-feeding, water-feeding and gas-feeding homogenizing device, a thirteenth valve is provided on the slurry output pipe, the discharge pipe is also connected to a fourteenth valve, and the thirteenth valve is connected to the fourteenth valve.

4. A system for purifying kaolin by multi-field coupling magnetic separation as claimed in claim 2, characterized in that: The branches are connected via three-way joints or four-way joints.

5. A method for purifying kaolin by multi-field coupling magnetic separation, characterized in that: A system for purifying kaolin using a multi-field coupled magnetic separation as claimed in claim 3, comprising: The high-pressure gas is introduced into the ore slurry in the ore-feeding, water-feeding and gas-feeding homogenizing device through the boosting device to form a high-pressure gas-liquid-solid miscible ore slurry; the high-pressure gas is introduced into the liquid in the sorting cavity through the boosting device to form a high-pressure gas-liquid miscible liquid; the excitation current is turned on to provide a background magnetic field for the magnetic yoke; the high-pressure gas-liquid-solid miscible ore slurry is input into the sorting cavity to perform magnetic separation under the conditions of a composite force field coupled with a high-pressure field containing gas van der Waals repulsion, a liquid flow force field, and a high-gradient magnetic field.

6. A method for purifying kaolin by multi-field coupling magnetic separation as claimed in claim 5, characterized in that: The following steps are involved: S101, close all valves, open the first valve, input the ore pulp to be magnetically separated into the ore feeding, water feeding, and gas feeding homogenization device, then close the first valve, open the eighth valve and the tenth valve, and pass high-pressure gas into the ore feeding, water feeding, and gas feeding homogenization device through the booster device to obtain high-pressure gas-liquid-solid miscible ore pulp; S102, opening the second valve, inputting the liquid into the separation chamber, then closing the second valve, opening the ninth valve, the eleventh valve, and the third valve, passing the high-pressure gas into the receiving device through the booster device and then inputting the high-pressure gas into the liquid in the separation chamber, to obtain a high-pressure gas-liquid miscible liquid; S103, turning on the exciting current of the exciting coil until the background magnetic induction intensity in the magnetic yoke reaches the required magnitude; S104, close the third valve and the ninth valve, open the fourth valve, and pass the high-pressure gas-liquid-solid miscible slurry into the separation cavity through the booster device, so as to form a composite force field including a high pressure field of gas van der Waals repulsion, a liquid flow force field and a high gradient magnetic field coupled in the separation cavity; S105, opening the sixth valve, the magnetic particles in the slurry are captured by the magnetic medium, and the non-magnetic particles flow into the receiving device.

7. A method for purifying kaolin by multi-field coupling magnetic separation as claimed in claim 6, characterized in that: Also includes: S106, opening the eleventh valve, the third valve and the reflux device to allow the slurry to reflux into the separation chamber for cyclic magnetic separation until the required number of cycles is reached, then closing the eleventh valve, the sixth valve, the ninth valve and opening the twelfth valve to discharge the magnetically separated slurry through the discharge port.

8. A method for purifying kaolin by multi-field coupling magnetic separation as claimed in claim 5, characterized in that: The following steps are involved: S201, close all valves, open the first valve, input the ore pulp to be magnetically separated into the ore feeding, water feeding, and gas feeding homogenization device, then close the first valve, open the eighth valve and the tenth valve, and pass high-pressure gas into the ore feeding, water feeding, and gas feeding homogenization device through the booster device to obtain high-pressure gas-liquid-solid miscible ore pulp; S202, opening the second valve, inputting the liquid into the sorting chamber, and then closing the second valve; S203, turning on the exciting current of the exciting coil until the background magnetic induction intensity in the magnetic yoke reaches a desired level; S204, closing the third valve and the ninth valve, opening the thirteenth valve and the fourteenth valve, and passing the high-pressure gas-liquid-solid miscible slurry into the separation cavity through the booster device, so as to form a composite force field in the separation cavity that includes a high-pressure field of gas van der Waals repulsion, a liquid flow force field, and a high-gradient magnetic field coupled; S205, opening the second valve, the magnetic particles in the slurry are captured by the magnetic medium, and the non-magnetic particles are discharged from the feed pipe.

9. A method for purifying kaolin by multi-field coupling magnetic separation as claimed in claim 5, characterized in that : The separation cavity can withstand a pressure of 0.8 to 10 MPa after being sealed; the pressure of the high-pressure gas-liquid-solid miscible slurry is 0.8 to 10 MPa; the high-pressure valve and pipeline can withstand a pressure of 0.8 to 10 MPa.

10. A method for purifying kaolin by multi-field coupling magnetic separation as claimed in claim 5, characterized in that The high-pressure gas-liquid-solid solution slurry output by the mine water supply and gas supply device has a particle size range of 0 to 0.074 mm, a slurry concentration of 1 to 50 wt%, a slurry temperature of 0 to 80 ° C, and a slurry pressure of 0.8 to 10 MPa. The boosting device is a reactor, a booster pump or a high-pressure gas cylinder. The boosting mode is gas boosting, and the gas is various gases soluble in the slurry; the high-pressure gas-liquid-solid solution slurry is introduced into the separation cavity at a slurry flow rate of 0.1 to 100 cm / s, the magnetic yoke provides a background magnetic induction magnetic field strength of 0.5 to 6.0 T, and the magnetic medium is steel wool, steel mesh or composite medium mesh.

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