Device for preparing high-purity magnesium chloride from brine

Abstract

The utility model discloses a kind of device for brine preparation high-purity magnesium chloride, belong to inorganic salt preparation technical field, including calcium sulfate precipitation unit, magnesium hydroxide precipitation unit, calcium carbonate precipitation and neutralization unit, membrane processing unit, magnesium chloride preparation unit.The device provided by the utility model not only can effectively separate calcium and magnesium ions, but also can realize the reuse of calcium carbonate and by-product of concentrated brine, by heating the completed liquid and matching spray drying process, the simplification of equipment, the reduction of energy consumption are realized.

Description

Technical Field

[0001] This utility model belongs to the field of inorganic salt preparation technology, specifically relating to an apparatus for producing high-purity magnesium chloride from brine. Background Technology

[0002] Currently, my country primarily utilizes brine for the production of low-value-added basic products such as magnesium chloride. There is limited application of electrolytic magnesium ingot production and subsequent alloying methods, which has resulted in slow technological development in the production of high-purity magnesium chloride from brine. The traditional process for producing magnesium chloride from brine involves transferring the old brine (after removing sodium chloride and potassium sulfate) to a magnesium chloride workshop, where it is evaporated and granulated before drying to obtain the finished product, magnesium chloride hexahydrate.

[0003] The existing technology has the following defects and shortcomings: residual sodium ions, potassium ions, calcium ions, sulfate ions and other impurity ions in the old brine are not effectively separated, resulting in low purity of magnesium chloride; the traditional brine preparation of magnesium chloride uses an evaporation device, which has the problems of many devices, high energy consumption, large capital investment and complicated maintenance.

[0004] In summary, the existing brine preparation technology for high-purity magnesium chloride has shortcomings and defects in actual production, so it is necessary to improve it. Utility Model Content

[0005] This invention addresses the shortcomings of existing methods by providing a device for producing high-purity magnesium chloride from brine. It effectively separates impurity ions using a magnesium hydroxide intermediate, which dissolves in hydrochloric acid to obtain a magnesium chloride solution. High-purity magnesium chloride can then be quickly and easily obtained through spray drying. The device not only achieves efficient separation of calcium and magnesium ions but also allows for the recycling of some byproducts, improving resource utilization.

[0006] To solve the above-mentioned technical problems, the technical solution of this utility model is as follows:

[0007] An apparatus for producing high-purity magnesium chloride from brine, characterized in that it comprises a calcium sulfate precipitation unit, a magnesium hydroxide precipitation unit, a calcium carbonate precipitation and neutralization unit, a membrane treatment unit, and a magnesium chloride preparation unit.

[0008] The calcium sulfate precipitation unit includes: a brine raw material tank, a calcium chloride solution raw material tank, a brine mixture storage tank, a calcium sulfate collection device, a calcium sulfate centrifuge, and a metering pump; the brine raw material pipeline is connected to the brine mixture storage tank via the brine metering pump, and the calcium chloride solution pipeline is also connected to the brine mixture storage tank via the calcium chloride metering pump; a calcium sulfate centrifuge is installed downstream of the brine mixture storage tank, and a calcium sulfate collection device is installed downstream of the centrifuge;

[0009] The magnesium hydroxide precipitation unit includes: a primary solution storage tank, a sodium hydroxide solution raw material tank, a magnesium hydroxide collection device, a plate and frame filter press, a metering pump, and a transfer pump; the sodium hydroxide solution pipeline is connected to the primary solution storage tank via the sodium hydroxide metering pump, and the calcium sulfate centrifuge is also connected to the primary solution storage tank via a post-discharge pipeline and a transfer pump; a plate and frame filter press is installed downstream of the primary solution storage tank, and the primary solution storage tank is connected to the plate and frame filter press via a primary solution pipeline and a transfer pump; a magnesium hydroxide collection device is installed downstream of the filter press;

[0010] The calcium carbonate precipitation and neutralization unit includes: a two-stage solution storage tank, a sodium carbonate solution raw material tank, a hydrochloric acid storage tank, a calcium carbonate reaction tank, a raw water tank, a calcium carbonate centrifuge, a feeder, a metering pump, and a transfer pump; the filter press is connected to the two-stage solution storage tank via a filtered liquid pipeline, and the sodium carbonate solution pipeline is also connected to the two-stage solution storage tank via a sodium carbonate metering pump; a calcium carbonate centrifuge is installed after the two-stage solution storage tank, and is then connected to the calcium carbonate reaction tank via a feeder; the centrifuge is connected to the raw water tank via a two-stage solution post-discharge liquid pipeline and a transfer pump; the first hydrochloric acid pipeline is connected to the calcium carbonate reaction tank via a hydrochloric acid metering pump; the reaction tank is connected to the calcium chloride solution raw material tank via a calcium carbonate reaction post-discharge pipeline and a calcium chloride transfer pump;

[0011] The membrane treatment unit includes: a raw water tank, a nanofiltration membrane module, a reverse osmosis membrane module, a feed pump, and a high-pressure pump; the raw water tank is connected to the nanofiltration membrane unit via pipelines and the high-pressure pump; the permeate outlet of the nanofiltration membrane unit is connected to the reverse osmosis membrane unit via a nanofiltration membrane permeate pipeline; the permeate outlet of the reverse osmosis membrane unit is connected to the finished liquid storage tank via a reverse osmosis membrane permeate pipeline; the concentrate outlets of the nanofiltration membrane unit and the reverse osmosis membrane unit are respectively connected to the concentrated brine tank via nanofiltration membrane concentrate pipelines and reverse osmosis membrane concentrate pipelines.

[0012] The magnesium chloride preparation unit includes: a finished liquid storage tank, a hydrochloric acid storage tank, a safety device, a heat exchanger, a spray drying device, a magnesium chloride collection device, a feeder, a metering pump, and a transfer pump. The magnesium hydroxide collection device is connected to the finished liquid storage tank via the feeder. The hydrochloric acid storage tank is connected to the finished liquid storage tank via another branch line, hydrochloric acid pipeline No. 2, after the hydrochloric acid metering pump. The finished liquid pipeline No. 1 is connected to the heat exchanger via the transfer pump and another branch line, finished liquid pipeline No. 2, and then connected to the finished liquid storage tank via a high-temperature material pipeline and a safety device pipeline No. 1. The steam inlet pipeline enters the heat exchanger and is discharged via a condensate pipeline. The finished liquid pipeline No. 1 is connected to the spray drying device via the transfer pump, the safety device, and another branch line, safety device pipeline No. 2. A magnesium chloride collection device is installed after the spray drying device.

[0013] Preferably, the brine mixture storage tank, the second-stage solution storage tank, the calcium carbonate reaction tank, and the finished liquid storage tank are also equipped with a stirring device; the first-stage solution storage tank and the finished liquid storage tank are also equipped with an online pH meter.

[0014] Preferably, the solution storage tank is provided with a feeding port at the top for feeding magnesium hydroxide flocculant polyacrylamide.

[0015] Preferably, a hopper and a weighing electronic belt scale are provided above the inlet of the finished liquid storage tank and the calcium carbonate reaction tank. The outlet of the hopper is connected to the weighing electronic belt scale, and the end of the weighing electronic belt scale is located above the inlet. This invention has the following advantages over the prior art:

[0016] 1. This utility model device is used to prepare high-purity magnesium chloride. Through the synergistic effect of magnesium hydroxide intermediate process and membrane treatment unit, sulfate ions are first removed by calcium sulfate precipitation unit, and then calcium and magnesium ions are efficiently separated by magnesium hydroxide precipitation unit. Finally, residual divalent ions are further intercepted by nanofiltration membrane and reverse osmosis membrane, which significantly reduces the content of impurities such as calcium and sulfate in magnesium chloride solution, laying the foundation for the preparation of high-purity magnesium chloride.

[0017] 2. By adopting the new device, the calcium carbonate solid obtained from the two-stage solution separation can be converted into calcium chloride solution through hydrochloric acid neutralization reaction. The solution is then returned to the calcium sulfate precipitation unit for recycling via the calcium carbonate reaction tank and calcium chloride transfer pump, avoiding waste of calcium resources, realizing material closed loop, and reducing raw material consumption costs.

[0018] 3. Using a novel device, the liquid after the second stage solution is concentrated and separated by a membrane treatment unit (nanofiltration membrane and reverse osmosis membrane), effectively retaining residual divalent ions and separating sodium chloride. The concentrated water can be directly discharged to the salt field for recycling, and the product water can be reused as the mother liquor of the finished liquid or as a dissolving medium. The water resource utilization rate is increased to more than 90%, and wastewater discharge is reduced.

[0019] 4. Using the device of this utility model, the drying and crystallization of magnesium chloride solution can be achieved in one step through spray drying process. The spray drying equipment is simple, practical, efficient and requires little capital investment.

[0020] 5. Using this utility model device, the completed liquid is circulated and heated through a shell-and-tube heat exchanger and a safety device to accelerate the neutralization reaction of hydrochloric acid and magnesium hydroxide, while reducing insoluble residues; the preheated solution directly enters the spray drying device, reducing energy consumption in the drying stage and achieving a dual improvement in reaction efficiency and energy utilization. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the process flow according to an embodiment of the present invention.

[0022] In the diagram: 1. Brine raw material tank; 2. Brine raw material pipeline; 3. Brine metering pump; 4. Calcium chloride solution raw material tank; 5. Calcium chloride solution pipeline; 6. Calcium chloride metering pump; 7. Brine mixture storage tank; 8. Brine mixture pipeline; 9. Calcium sulfate centrifuge; 10. Calcium sulfate collection pipeline; 11. Calcium sulfate collection device; 12. After-spinning liquid pipeline; 13. Transfer pump; 14. Sodium hydroxide solution raw material tank; 15. Sodium hydroxide solution pipeline; 16. Sodium hydroxide metering device. 17. Pump; 18. First-stage solution storage tank; 19. First-stage solution pipeline; 20. Transfer pump; 21. Plate and frame filter press; 22. Magnesium hydroxide collection pipeline; 23. Magnesium hydroxide collection device; 24. Post-filtration liquid pipeline; 25. Sodium carbonate solution raw material tank; 26. Sodium carbonate solution pipeline; 27. Sodium carbonate metering pump; 28. Second-stage solution storage tank; 29. ​​Second-stage solution pipeline; 30. Calcium carbonate centrifuge; 31. Calcium carbonate collection pipeline; 32. Feeder; 33. Hydrochloric acid Storage tank; 33. Hydrochloric acid metering pump; 34. Hydrochloric acid pipeline No. 1; 35. Calcium carbonate reaction tank; 36. Calcium carbonate post-reaction pipeline; 37. Calcium chloride transfer pump; 38. Second-stage solution post-discharge pipeline; 39. Transfer pump; 40. Raw water tank; 41. Raw water tank pipeline; 42. High-pressure pump; 43. Nanofiltration membrane unit; 44. Nanofiltration membrane permeate pipeline; 45. Reverse osmosis membrane unit; 46. Reverse osmosis membrane permeate pipeline; 47. Nanofiltration membrane concentrate pipeline; 48. Reverse osmosis membrane concentrate. Piping; 49. Magnesium hydroxide conveying pipeline; 50. Feeder; 51. Hydrochloric acid No. 2 pipeline; 52. Finished liquid storage tank; 53. Finished liquid No. 1 pipeline; 54. Transfer pump; 55. Safety device; 56. Safety device No. 1 pipeline; 57. Safety device No. 2 pipeline; 58. Finished liquid No. 2 pipeline; 59. Heat exchanger; 60. High-temperature material pipeline; 61. Steam inlet pipeline; 62. Steam outlet pipeline; 63. Spray drying device; 64. Magnesium chloride collection device. Detailed Implementation

[0023] The technical solutions and effects of the embodiments of this utility model will be further described in detail below with reference to the accompanying drawings.

[0024] Reference Figure 1 The apparatus used in this invention includes a brine raw material tank 1, a calcium chloride solution raw material tank 4, a sodium hydroxide solution raw material tank 14, a sodium carbonate solution raw material tank 24, a hydrochloric acid storage tank 32, a brine mixed liquid storage tank 7, a first-stage solution storage tank 17, a second-stage solution storage tank 27, a raw water tank 40, a finished liquid storage tank 52, a calcium sulfate collection device 11, a magnesium hydroxide collection device 22, a nanofiltration membrane device 43, a reverse osmosis membrane device 45, a spray drying equipment 63, a magnesium chloride collection device 64, a safety device 55, a shell-and-tube heat exchanger 59, a plate and frame filter press 20, a centrifuge, a feeder, a hopper, a weighing electronic belt scale, and matching metering pumps, flow meters, transfer pumps, pipelines, valves, and a control system.

[0025] Brine raw material pipeline 2 is connected to brine mixed liquid storage tank 7 via brine metering pump 3. Calcium chloride solution pipeline 5 is connected to brine mixed liquid storage tank 7 via calcium chloride metering pump 6. Brine mixed liquid storage tank 7 is equipped with a stirring device. A calcium sulfate centrifuge 9 is installed downstream of brine mixed liquid storage tank 7, and a calcium sulfate collection device 11 is installed downstream of the centrifuge. Sodium hydroxide solution pipeline 15 is connected to first-stage solution storage tank 17 via sodium hydroxide metering pump 16. Calcium sulfate centrifuge 9 is also connected to first-stage solution storage tank 17 via post-spinning liquid pipeline 12 and transfer pump 13. First-stage solution storage tank 17 is equipped with an online pH meter, and a flocculant polyacrylamide feeding port is located above the tank. A plate and frame filter press 20 is installed downstream of first-stage solution storage tank 17. First-stage solution storage tank 17 is connected to plate and frame filter press 20 via first-stage solution pipeline 18 and transfer pump 19. A magnesium hydroxide collection device 22 is installed downstream of the filter press. Filter press 20 is connected to second-stage solution storage tank 27 via post-filtering liquid pipeline 23. Sodium carbonate solution pipeline 25 is connected to secondary solution storage tank 27 via sodium carbonate metering pump 26. Secondary solution storage tank 27 is equipped with a stirring device. A calcium carbonate centrifuge 29 is installed after secondary solution storage tank 27, and then connected to calcium carbonate reaction tank 35 via feeder 31. Centrifuge 29 is connected to raw water tank 40 via secondary solution post-reaction pipeline 38 and transfer pump 39. Hydrochloric acid pipeline 34 is connected to calcium carbonate reaction tank 35 via hydrochloric acid metering pump 33. Calcium carbonate reaction tank 35 is equipped with a stirring device. After calcium carbonate reaction, reaction tank 35 is connected to calcium chloride solution raw material tank 4 via calcium chloride transfer pump 37 via calcium carbonate reaction post-reaction pipeline 36. The raw water tank pipeline 41 is connected to the nanofiltration membrane device 43 via the high-pressure pump 42. The permeate outlet of the nanofiltration membrane device 43 is connected to the reverse osmosis membrane device 45 via the nanofiltration membrane permeate pipeline 44. The permeate outlet of the reverse osmosis membrane device 45 is connected to the finished liquid storage tank 52 via the reverse osmosis membrane permeate pipeline 46. The concentrate outlets of the nanofiltration membrane device 43 and the reverse osmosis membrane device 45 are respectively connected to the concentrated brine tank via the nanofiltration membrane concentrate pipeline 47 and the reverse osmosis membrane concentrate pipeline 48. Magnesium hydroxide collection device 22 is connected to finished liquid storage tank 52 via feeder 50, and then to finished liquid storage tank 52 via hydrochloric acid metering pump 33 and another branch line hydrochloric acid pipeline 51. Finished liquid storage tank 52 is equipped with an online pH meter and a stirring device. Finished liquid pipeline 53 is connected to heat exchanger 59 via transfer pump 54 and another branch line finished liquid pipeline 58, and then to finished liquid storage tank 52 via high temperature material pipeline 60 and safety device pipeline 56. Steam enters heat exchanger 59 via steam inlet pipeline 61 and is discharged via steam outlet pipeline 62. Finished liquid pipeline 53 is connected to spray drying device 63 via transfer pump 54, safety device 55 and another branch line safety device pipeline 57. Magnesium chloride collection device 64 is installed after spray drying device 63.

[0026] Work process description:

[0027] The brine in the brine raw material tank 1 is added to the brine mixed liquid storage tank 7 via the brine raw material pipeline 2 and the brine metering pump 3. The calcium chloride solution in the calcium chloride solution raw material tank 4 is added to the brine mixed liquid storage tank 7 via the calcium chloride solution pipeline 5 and the calcium chloride metering pump 6. The brine mixed liquid storage tank 7 is equipped with a stirring device and is stirred for 20-60 minutes. After the solution in the brine mixed liquid storage tank 7 reacts, it is separated by the calcium sulfate centrifuge 9, and the solid falls into the calcium sulfate collection device 11 through the calcium sulfate collection pipeline 10. The sodium hydroxide solution in the raw material tank 14 is first transported to the first-stage solution storage tank 17 via the sodium hydroxide solution pipeline 15 and the sodium hydroxide metering pump 16. Then, the solution separated by the calcium sulfate centrifuge 9 enters the first-stage solution storage tank 17 via the after-spinning liquid pipeline 12 and the transfer pump 13 (calcium ion concentration 0.82-5.65 g / L, magnesium ion concentration 11.32-33.27 g / L). The first-stage solution storage tank 17 is equipped with an online pH meter (pH: 12.28-13.84) and a flocculant feeding port at the top of the tank. The flocculant is polyacrylamide, with a mass of 2.81~3.83 kg added. After settling for 30-90 minutes, the material is pressurized by the transfer pump 19 and enters the plate and frame filter press 20 for solid-liquid separation. The solid magnesium hydroxide filter cake is stored in the magnesium hydroxide collection device 22 via the magnesium hydroxide collection pipeline 21, and the liquid is transported to the second-stage solution storage tank 27 (calcium ion concentration 0.76-4.75 g / L) via the filter press liquid pipeline 23. Sodium carbonate solution in sodium carbonate solution raw material tank 24 is added to secondary solution storage tank 27 via sodium carbonate solution pipeline 25 and sodium carbonate metering pump 26. After stirring for 30-90 minutes, the material is separated by calcium carbonate centrifuge 29. The solid is conveyed to hopper and weighed by electronic belt scale via feeder 31, and then falls into calcium carbonate reaction tank 35. The solution is conveyed to raw water tank 40 via secondary solution after-effect pipeline 38 and transfer pump 39. Then, hydrochloric acid solution in hydrochloric acid storage tank 32 is added to calcium carbonate reaction tank 35 via hydrochloric acid No. 1 pipeline 34 and hydrochloric acid metering pump 33. After stirring and reacting for 60-120 minutes, the solution is sent to calcium chloride solution raw material tank 4 via calcium carbonate reaction after-effect pipeline 36 and transfer pump 37. The solution in the raw water tank 40 enters the nanofiltration membrane device 43 through the raw water tank pipeline 41 and the high-pressure pump 42. The nanofiltration membrane permeate enters the reverse osmosis membrane device 45 through the nanofiltration membrane permeate pipeline 44. The reverse osmosis membrane permeate enters the finished liquid storage tank 52 through the reverse osmosis membrane permeate pipeline 46. The concentrates from the nanofiltration membrane device 43 and the reverse osmosis membrane device 45 enter the concentrated brine tank through the nanofiltration membrane concentrate pipeline 47 and the reverse osmosis membrane concentrate pipeline 48, respectively.Magnesium hydroxide in magnesium hydroxide collection tank 22 is conveyed to hopper and weighed by electronic belt scale via feeder 50, and then falls into finished liquid storage tank 52. Hydrochloric acid solution in hydrochloric acid storage tank 32 is added to finished liquid storage tank 52 via hydrochloric acid pipeline No. 2 51 and hydrochloric acid metering pump 33. Finished liquid storage tank 52 is equipped with online pH meter (pH: 5-8) and stirring device. After stirring for 30-60 minutes, steam is introduced into heat exchanger. Steam enters heat exchanger 59 from steam inlet pipe 61 and exits from steam outlet pipe 62. Liquid in finished liquid storage tank 52 enters the low temperature material inlet of transfer pump 54 via finished liquid pipeline No. 2 58. After heat exchange in heat exchanger 59, it enters safety device No. 1 pipe 56 via high temperature material pipe 60, transferring the solution to finished liquid storage tank 52. During the circulation of liquid through heat exchanger 59, the inlet and outlet valves of safety device 55 are closed. After the liquid material reaches the designated temperature (50-70℃), close the valves on both sides of the heat exchanger and open the valves on both sides of the safety device. This allows the liquid to flow through the first pipeline 53 and the transfer pump 54 into the safety device 55, and then back to the liquid storage tank 52 via the first pipeline 56 of the safety device, trapping unreacted solid particles in the storage tank. After circulating for a certain time (30-60 minutes), close the valve on the first pipeline 56 of the safety device and open the valve on the second pipeline 57 of the safety device, allowing the liquid to enter the spray dryer 63 (inlet temperature 200-400℃, feed rate 1-2 m³ / h) for one-step drying to obtain magnesium chloride powder (purity 44.87-46.49%, yield 90.8-96.5%).

[0028] The above-disclosed embodiments are merely preferred embodiments of the present utility model and should not be construed as limiting the scope of the present utility model. Those skilled in the art can understand that implementing all or part of the above-described embodiments and making equivalent changes in accordance with the claims of the present utility model are still within the scope of the utility model.

Claims

1. An apparatus for producing high-purity magnesium chloride from brine, characterized in that, It includes a calcium sulfate precipitation unit, a magnesium hydroxide precipitation unit, a calcium carbonate precipitation and neutralization unit, a membrane treatment unit, and a magnesium chloride preparation unit; The calcium sulfate precipitation unit includes: a brine raw material tank (1), a calcium chloride solution raw material tank (4), a brine mixture storage tank (7), a calcium sulfate collection device (11), a calcium sulfate centrifuge (9), and a metering pump; the brine raw material pipeline (2) is connected to the brine mixture storage tank (7) through the brine metering pump (3), and the calcium chloride solution pipeline (5) is also connected to the brine mixture storage tank (7) through the calcium chloride metering pump (6); a calcium sulfate centrifuge (9) is installed after the brine mixture storage tank (7), and a calcium sulfate collection device (11) is installed after the centrifuge; The magnesium hydroxide precipitation unit includes: a first-stage solution storage tank (17), a sodium hydroxide solution raw material tank (14), a magnesium hydroxide collection device (22), a plate and frame filter press (20), a metering pump (16), and a transfer pump; the sodium hydroxide solution pipeline (15) is connected to the first-stage solution storage tank (17) through the sodium hydroxide metering pump (16), and the calcium sulfate centrifuge (9) is also connected to the first-stage solution storage tank (17) through the after-spinning liquid pipeline (12) and the transfer pump (13); the first-stage solution storage tank (17) is equipped with a plate and frame filter press (20), and the first-stage solution storage tank (17) is connected to the plate and frame filter press (20) through a first-stage solution pipeline (18) and the transfer pump (19), and the magnesium hydroxide collection device (22) is installed after the filter press (20); The calcium carbonate precipitation and neutralization unit includes: a two-stage solution storage tank (27), a sodium carbonate solution raw material tank (24), a hydrochloric acid storage tank (32), a calcium carbonate reaction tank (35), a raw water tank (40), a calcium carbonate centrifuge (29), a feeder, a metering pump, and a transfer pump; the filter press (20) is connected to the two-stage solution storage tank (27) through a filter-filtered liquid pipeline (23), and the sodium carbonate solution pipeline (25) is also connected to the two-stage solution storage tank (27) through a sodium carbonate metering pump (26); the two-stage solution A calcium carbonate centrifuge (29) is installed after the storage tank (27), and then connected to the calcium carbonate reaction tank (35) through the feeder (31). The centrifuge (29) is connected to the raw water tank (40) through the two-stage solution after-spinning pipeline (38) and the transfer pump (39). The hydrochloric acid No. 1 pipeline (34) is connected to the calcium carbonate reaction tank (35) through the hydrochloric acid metering pump (33). The reaction tank (35) is connected to the calcium chloride solution raw material tank (4) through the calcium carbonate reaction pipeline (36) and the calcium chloride transfer pump (37). The membrane treatment unit includes: a raw water tank (40), a nanofiltration membrane module (43), a reverse osmosis membrane module (45), a feed pump, and a high-pressure pump; the raw water tank (40) is connected to the nanofiltration membrane device (43) through a pipeline (41) and a high-pressure pump (42); the permeate outlet of the nanofiltration membrane device (43) is connected to the reverse osmosis membrane device (45) through a nanofiltration membrane permeate pipeline (44); the permeate outlet of the reverse osmosis membrane device (45) is connected to the finished liquid storage tank (52) through a reverse osmosis membrane permeate pipeline (46); the concentrate outlets of the nanofiltration membrane device (43) and the reverse osmosis membrane device (45) are respectively connected to the concentrated brine tank through a nanofiltration membrane concentrate pipeline (47) and a reverse osmosis membrane concentrate pipeline (48); The magnesium chloride preparation unit includes: a finished liquid storage tank (52), a hydrochloric acid storage tank (32), a safety device (55), a heat exchanger (59), a spray drying device (63), a magnesium chloride collection device (64), a feeder, a metering pump, and a transfer pump; the magnesium hydroxide collection device (22) is connected to the finished liquid storage tank (52) via the feeder (50), and the hydrochloric acid storage tank (32) is connected to the finished liquid storage tank (52) via another branch line, hydrochloric acid pipeline No. 2 (51), after the hydrochloric acid metering pump (33); the finished liquid pipeline No. 1 (53) is connected to the hydrochloric acid pipeline No. 1 via the transfer pump (54) and thereafter. The other branch line completes the liquid No. 2 pipeline (58) and connects to the heat exchanger (59), and then connects to the liquid storage tank (52) via the high temperature material pipeline (60) and the safety device No. 1 pipeline (56). The steam inlet pipeline (61) enters the heat exchanger (59) and then discharges through the condensate pipeline (62). The liquid No. 1 pipeline (53) is connected to the spray drying device (63) via the transfer pump (54), the safety device (55) and the other branch line safety device No. 2 pipeline (57). The spray drying device (63) is equipped with a magnesium chloride collection device (64).

2. The apparatus for producing high-purity magnesium chloride from brine according to claim 1, characterized in that, The brine mixture storage tank (7), the second-stage solution storage tank (27), the calcium carbonate reaction tank (35), and the finished liquid storage tank (52) are also equipped with stirring devices; the first-stage solution storage tank (17) and the finished liquid storage tank (52) are also equipped with online pH meters.

3. The apparatus for producing high-purity magnesium chloride from brine according to claim 1, characterized in that, The solution storage tank (17) is equipped with a flocculant feeding port above it.

4. The apparatus for producing high-purity magnesium chloride from brine according to claim 1, characterized in that, The finished liquid storage tank (52) and the calcium carbonate reaction tank (35) are equipped with a hopper and a weighing electronic belt scale above the feed inlet. The outlet of the hopper is connected to the weighing electronic belt scale, and the end of the weighing electronic belt scale is located above the feed inlet.

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