Continuous preparation of hexafluorophosphate salts

Abstract

The application relates to the field of chemical equipment, and discloses a continuous preparation device for hexafluorophosphate, which comprises a first reaction kettle and a second reaction kettle. A gas outlet of the first reaction kettle is connected with the second reaction kettle, and is used for feeding the exhaust gas of the first reaction kettle into the second reaction kettle. A material outlet of the second reaction kettle is connected with a liquid feeding port of the first reaction kettle, and is used for transferring the material of the second reaction kettle into the first reaction kettle. The first reaction kettle further comprises a material outlet, and the obtained hexafluorophosphate crude product is discharged from the material outlet of the first reaction kettle. The second reaction kettle further comprises a gas outlet, and the tail gas is discharged from the gas outlet of the second reaction kettle.

Description

Technical Field

[0001] This application relates to the field of chemical equipment, specifically to a continuous preparation apparatus for hexafluorophosphate. Background Technology

[0002] Hexafluorophosphate (LiPF6) is a key solute in lithium-ion battery electrolytes, and the hydrofluoric acid solvent method is the most common and mature technical route. Currently, the preparation of hexafluorophosphate mainly adopts industrialized batch production methods, which have low production efficiency. Utility Model Content

[0003] In view of the above-mentioned shortcomings of the prior art, the purpose of this disclosure is to provide a continuous preparation apparatus for hexafluorophosphate.

[0004] To achieve the above objectives, the present disclosure adopts the following technical solution:

[0005] This disclosure provides a continuous preparation apparatus for hexafluorophosphate, including a primary reactor and a secondary reactor. The gas outlet of the primary reactor is connected to the secondary reactor for introducing the exhaust gas from the primary reactor into the secondary reactor. The material outlet of the secondary reactor is connected to the liquid inlet of the primary reactor for transferring the material from the secondary reactor into the primary reactor. The primary reactor also includes a material outlet, from which the crude hexafluorophosphate product obtained from the reaction is discharged. The secondary reactor also includes a gas outlet, from which tail gas is discharged.

[0006] In some embodiments of this disclosure, the continuous preparation apparatus for hexafluorophosphate further includes a second packed tower. The liquid inlet of the second packed tower is connected to a lithium source or sodium source storage tank and / or a lithium source or sodium source transfer tank. The liquid outlet of the second packed tower is connected to the liquid inlet of the secondary reactor. The gas inlet of the second packed tower is connected to the gas outlet of the secondary reactor. The gas outlet of the second packed tower is connected to the top condenser of the second packed tower.

[0007] In some embodiments of this disclosure, the continuous preparation apparatus for hexafluorophosphate further includes a second packed tower top demister, the gas inlet of the second packed tower top condenser is connected to the gas outlet of the secondary reactor and / or the gas outlet of the second packed tower, the gas outlet of the second packed tower top condenser is connected to the gas inlet of the second packed tower top demister, and the gas outlet of the second packed tower top demister discharges tail gas.

[0008] In some embodiments of this disclosure, the condensate outlet of the second packed tower top condenser is connected to the liquid inlet of the secondary reactor and / or the liquid inlet of the second packed tower.

[0009] In some embodiments of this disclosure, the continuous preparation apparatus for hexafluorophosphate further includes a first packed tower, the liquid inlet of the first packed tower being connected to the liquid outlet of the primary reactor, the liquid outlet of the first packed tower being connected to the liquid inlet of the primary reactor; the gas inlet of the first packed tower being connected to the gas outlet of the primary reactor, and the gas outlet of the first packed tower being connected to the top condenser of the first packed tower.

[0010] In some embodiments of this disclosure, the continuous preparation apparatus for hexafluorophosphate further includes a first packed tower top demister, the gas inlet of the first packed tower top condenser is connected to the gas outlet of the primary reactor and / or the gas outlet of the first packed tower, the gas outlet of the first packed tower top condenser is connected to the gas inlet of the first packed tower top demister, and the gas outlet of the first packed tower top demister is connected to the gas inlet of the secondary reactor.

[0011] In some embodiments of this disclosure, the condensate outlet of the first packed tower top condenser is connected to the liquid inlet of the primary reactor and / or the liquid inlet of the first packed tower.

[0012] In some embodiments of this disclosure, the continuous preparation apparatus for hexafluorophosphate further includes a phosphorus pentafluoride preparation vessel, the gas outlet of which is connected to a primary reaction vessel.

[0013] In some embodiments of this disclosure, the continuous preparation apparatus for hexafluorophosphate further includes:

[0014] A phosphorus pentachloride dropping vessel, used for adding phosphorus pentachloride dropwise into a phosphorus pentafluoride preparation vessel, is conical in shape; and

[0015] The phosphorus pentachloride high-level tank is used to add phosphorus pentachloride into the phosphorus pentachloride dripping tank.

[0016] In some embodiments of this disclosure, the continuous preparation apparatus for hexafluorophosphate further includes a third packed tower, the liquid inlet of which is connected to a hydrofluoric acid storage tank and / or a hydrofluoric acid transfer tank, and the liquid outlet of which is connected to the inlet of a phosphorus pentafluoride preparation reactor for feeding hydrofluoric acid into the phosphorus pentafluoride preparation reactor; the gas outlet of which is connected to a condenser at the top of the third packed tower, and the gas inlet of which is connected to the phosphorus pentafluoride preparation reactor.

[0017] In some embodiments of this disclosure, the continuous preparation apparatus for hexafluorophosphate further includes a third packed tower top demister, which is connected to a third packed tower top condenser, and the gas outlet of the third packed tower top demister is connected to a primary reaction vessel.

[0018] In some embodiments of this disclosure, the condensate outlet of the top condenser of the third packed tower is connected to the feed inlet of the phosphorus pentafluoride preparation vessel and / or the liquid feed inlet of the third packed tower.

[0019] In some embodiments of this disclosure, the continuous preparation apparatus for hexafluorophosphate further includes a tail gas treatment device, which includes a demister, a condenser, a high-pressure distillation column, and a water absorption device connected in sequence.

[0020] In some embodiments of this disclosure, the water absorption device includes a multi-stage ordinary water absorption tower and a multi-stage ultrapure water absorption tower. The gas inlet of the first stage of the multi-stage ordinary water absorption tower is connected to the gas outlet of the high-pressure distillation tower. The gas outlet of each stage of the ordinary water absorption tower is connected to the gas inlet of the next stage of the ordinary water absorption tower. The gas outlet of the last stage of the ordinary water absorption tower is connected to the gas inlet of the first stage of the ultrapure water absorption tower. The gas outlet of the last stage of the ultrapure water absorption tower is connected to a waste gas treatment system. Both the multi-stage ordinary water absorption tower and the multi-stage ultrapure water absorption tower include a liquid outlet, a self-circulating inlet connected to the liquid outlet, and a liquid inlet. The liquid inlet of the previous stage of the ordinary water absorption tower is connected to the liquid outlet of the next stage of the ordinary water absorption tower. The liquid inlet of the last stage of the ordinary water absorption tower is connected to an ordinary water storage tank. The liquid outlet of the first stage of the ordinary water absorption tower is connected to a hydrochloric acid storage tank. The liquid inlet of the previous stage of the ultrapure water absorption tower is connected to the liquid outlet of the next stage of the ultrapure water absorption tower. The liquid inlet of the last stage of the ultrapure water absorption tower is connected to an ultrapure water storage tank. The liquid outlet of the first stage of the ultrapure water absorption tower is connected to an electronic-grade hydrochloric acid storage tank.

[0021] In some embodiments of this disclosure, the continuous preparation apparatus for hexafluorophosphate further includes a hexafluorophosphate transfer tank, a filtration device, and a crude hexafluorophosphate treatment device. The hexafluorophosphate transfer tank is connected to the material outlet of the primary reactor, the filtration device is connected to the hexafluorophosphate transfer tank, and the crude hexafluorophosphate treatment device is connected to the filtration device.

[0022] The continuous preparation apparatus for hexafluorophosphate provided in this disclosure can bring beneficial technical effects. For example, in some embodiments of this disclosure, the crude hexafluorophosphate and the tail gas are discharged from different reaction vessels, which can obtain crude hexafluorophosphate that is easy to purify and otherwise post-process, and tail gas that is easy to treat. Attached Figure Description

[0023] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0024] Figure 1 A schematic diagram of the continuous preparation apparatus for hexafluorophosphate in some embodiments is shown;

[0025] Figure 2A schematic diagram of the structure of a water absorption device according to some embodiments of the present disclosure is shown.

[0026] In the picture:

[0027] 1-High-level tank for phosphorus pentachloride, 2-Phosphorus pentachloride dripping tank, 3-Phosphorus pentafluoride preparation kettle, 4-Second packed tower, 5-First packed tower, 6-First stage reaction kettle, 7-Second stage reaction kettle, 8-Third packed tower, 9-Second packed tower top condenser, 10-Second packed tower top demister, 11-First packed tower top condenser, 12-First packed tower top demister, 13a, 13b-Third packed tower top condenser, 14-Third packed tower top demister;

[0028] 100 - Water absorption unit; 110 - First-stage ordinary water absorption tower; 111 - Liquid outlet of the first-stage ordinary water absorption tower; 112 - Self-circulation inlet of the first-stage ordinary water absorption tower; 113 - Liquid inlet of the first-stage ordinary water absorption tower; 114 - Gas inlet of the first-stage ordinary water absorption tower; 115 - Gas outlet of the first-stage ordinary water absorption tower; 120 - Second-stage ordinary water absorption tower; 121 - Liquid outlet of the second-stage ordinary water absorption tower; 122 - ... Self-circulation inlet, 123 - Liquid inlet of the second-stage ordinary water absorption tower, 124 - Gas inlet of the second-stage ordinary water absorption tower, 125 - Gas outlet of the second-stage ordinary water absorption tower, 130 - First-stage ultrapure water absorption tower, 131 - Liquid outlet of the first-stage ultrapure water absorption tower, 132 - Self-circulation inlet of the first-stage ultrapure water absorption tower, 133 - Liquid inlet of the first-stage ultrapure water absorption tower, 134 - Gas inlet of the first-stage ultrapure water absorption tower, 135 - [Insert inlet name here] of the first-stage ultrapure water absorption tower. Gas outlet; 140 - Second-stage ultrapure water absorption tower; 141 - Liquid outlet of the second-stage ultrapure water absorption tower; 142 - Self-circulation inlet of the second-stage ultrapure water absorption tower; 143 - Liquid inlet of the second-stage ultrapure water absorption tower; 144 - Gas inlet of the second-stage ultrapure water absorption tower; 145 - Gas outlet of the second-stage ultrapure water absorption tower; 150 - Third-stage ultrapure water absorption tower; 151 - Liquid outlet of the third-stage ultrapure water absorption tower; 152 - Self-circulation inlet of the third-stage ultrapure water absorption tower. 153 - Liquid inlet of the third-stage ultrapure water absorption tower; 154 - Gas inlet of the third-stage ultrapure water absorption tower; 155 - Gas outlet of the third-stage ultrapure water absorption tower; 160 - Fourth-stage ultrapure water absorption tower; 161 - Liquid outlet of the fourth-stage ultrapure water absorption tower; 162 - Self-circulation inlet of the fourth-stage ultrapure water absorption tower; 163 - Liquid inlet of the fourth-stage ultrapure water absorption tower; 164 - Gas inlet of the fourth-stage ultrapure water absorption tower; 165 - Gas outlet of the fourth-stage ultrapure water absorption tower. Detailed Implementation

[0029] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0030] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0031] Figure 1 A schematic diagram of the structure of a continuous preparation apparatus for hexafluorophosphate according to some embodiments is shown.

[0032] like Figure 1 As shown in some embodiments of this disclosure, the continuous preparation apparatus for hexafluorophosphate may include a primary reactor 6 and a secondary reactor 7. The gas outlet of the primary reactor 6 is connected to the secondary reactor 7 via a pipeline, for introducing the exhaust gas from the primary reactor 6 into the secondary reactor 7. The material outlet of the secondary reactor 7 is connected to the liquid inlet of the primary reactor 6 via a pipeline, for transferring the material from the secondary reactor 7 into the primary reactor 6. The primary reactor 6 may also include a material outlet from which the crude hexafluorophosphate product obtained from the reaction is discharged. The secondary reactor 7 may also include a gas outlet (not shown in the figure), from which the tail gas is discharged.

[0033] In some embodiments of this disclosure, the crude hexafluorophosphate and the tail gas are discharged from different reactors, resulting in crude hexafluorophosphate that is easy to purify and process, and tail gas that is easy to treat. For example, in the continuous hexafluorophosphate preparation apparatus according to some embodiments of this disclosure, the concentration of phosphorus pentafluoride in the tail gas is ≤1.0 ppm.

[0034] like Figure 1As shown in some embodiments of this disclosure, the continuous preparation apparatus for hexafluorophosphate may further include a second packed tower 4. The liquid inlet of the second packed tower 4 is connected to a lithium fluoride storage tank and / or a lithium or sodium source transfer tank, and the liquid outlet of the second packed tower 4 is connected to the liquid inlet of the secondary reactor 7, for feeding a hydrofluoric acid solution containing a lithium or sodium source into the secondary reactor 7. The gas inlet of the second packed tower 4 is connected to the gas outlet of the secondary reactor 7, and the gas outlet of the second packed tower 4 is connected to the top condenser 9 of the second packed tower. By feeding the lithium or sodium source into the secondary reactor 7 through the second packed tower 4, the presence of phosphorus pentafluoride gas in the exhaust gas discharged from the secondary reactor 7 can be further avoided, thus ensuring subsequent exhaust gas treatment. Furthermore, the exhaust gas discharged from the secondary reactor 7 passes through the second packed tower 4 and then enters the top condenser 9 of the second packed tower, which can also provide preliminary cooling of the exhaust gas, facilitating the subsequent condensation of hydrogen fluoride gas.

[0035] like Figure 1 As shown, in some embodiments of this disclosure, the continuous preparation apparatus for hexafluorophosphate may further include a second packed column top demister 10 connected to the second packed column top condenser 9. The gas inlet of the second packed column top condenser 9 is connected to the gas outlet of the secondary reactor 7, and the gas outlet of the second packed column top condenser 9 is connected to the gas inlet of the second packed column top demister 10. The gas outlet of the second packed column top demister 10 discharges tail gas. In other embodiments of this disclosure, the gas inlet of the second packed column top condenser 9 may also be connected to the gas outlet of the second packed column 4.

[0036] like Figure 1 As shown, in some embodiments of this disclosure, the condensate outlet of the second packed tower top condenser 9 can be connected to the liquid inlet of the secondary reactor 7. For example, in some embodiments of this disclosure, the liquid returning from the second packed tower top demister 10 passes through the second packed tower top condenser 9 and flows back into the secondary reactor 7 together with the condensate from the second packed tower top condenser 9.

[0037] Those skilled in the art will understand that, although Figure 1 Only one second packed tower top condenser 9 and one second packed tower top demister 10 are shown, but this is only exemplary. The gas outlet of the secondary reactor 7 may also be connected to other numbers of second packed tower top condensers 9 and / or second packed tower top demisters 10.

[0038] like Figure 1As shown in some embodiments of this disclosure, the continuous preparation apparatus for hexafluorophosphate may further include a first packed tower 5. The liquid inlet of the first packed tower 5 is connected to the liquid outlet of the secondary reactor 7, and the liquid outlet of the first packed tower 5 is connected to the liquid inlet of the primary reactor 6. The gas inlet of the first packed tower 5 is connected to the gas outlet of the primary reactor 6, and the gas outlet of the first packed tower 5 is connected to the top condenser 11 of the first packed tower.

[0039] The gas discharged from the primary reactor 6 enters the secondary reactor 7 through the first packed tower 5, which allows the phosphorus pentafluoride in the gas to react fully with the lithium or sodium source, and also cools the gas discharged from the primary reactor 6.

[0040] like Figure 1 As shown, in some embodiments of this disclosure, the continuous preparation apparatus for hexafluorophosphate may further include a first packed tower top demister 12 connected to a first packed tower top condenser 11. The gas inlet of the first packed tower top condenser 11 is connected to the gas outlet of the primary reactor 6, and the gas outlet of the first packed tower top condenser 11 is connected to the gas inlet of the first packed tower top demister 12. The gas outlet of the first packed tower top demister 12 is connected to the gas inlet of the secondary reactor 7. In other embodiments of this disclosure, the gas inlet of the first packed tower top condenser 11 may be connected to the gas outlet of the first packed tower 5.

[0041] like Figure 1 As shown, in some embodiments of this disclosure, the condensate outlet of the first packed tower top condenser 11 can be connected to the liquid inlet of the primary reactor 6. In other embodiments of this disclosure, the condensate outlet of the first packed tower top condenser 11 can be connected to the liquid inlet of the first packed tower 5. For example, in some embodiments of this disclosure, the liquid returning from the first packed tower top demister 12, after passing through the first packed tower top condenser 11, flows back into the primary reactor 6 together with the condensate from the first packed tower top condenser 11.

[0042] Those skilled in the art will understand that, although Figure 1 Only one first packed tower top condenser 11 and one first packed tower top demister 12 are shown, but this is only exemplary. The gas outlet of the first-stage reactor 6 may also be connected to other numbers of first packed tower top condensers 11 and / or first packed tower top demisters 12.

[0043] Those skilled in the art will understand that the continuous preparation apparatus for hexafluorophosphate according to some embodiments of this disclosure can be used for the continuous preparation of hexafluorophosphate.

[0044] like Figure 1As shown, in some embodiments of this disclosure, the continuous preparation apparatus for hexafluorophosphate may further include a phosphorus pentafluoride preparation vessel 3, the gas outlet of which is connected to a primary reaction vessel 6.

[0045] like Figure 1 As shown, in some embodiments of this disclosure, the continuous preparation apparatus for hexafluorophosphate may further include a phosphorus pentachloride dropping tank 2 for dropping phosphorus pentachloride into a phosphorus pentafluoride preparation vessel 3.

[0046] like Figure 1 As shown, in some embodiments of this disclosure, the phosphorus pentachloride dripping tank 2 is conical. The conical shape of the phosphorus pentachloride dripping tank 2 facilitates material feeding, and even without a stirring device inside the phosphorus pentachloride dripping tank 2, material agglomeration will not occur over time.

[0047] In some embodiments of this disclosure, a viewing window (not shown in the figure) is provided on the phosphorus pentachloride dropping tank 2.

[0048] like Figure 1 As shown in some embodiments of this disclosure, the continuous preparation apparatus for hexafluorophosphate may further include a phosphorus pentachloride high-level tank 1 for adding phosphorus pentachloride into a phosphorus pentachloride dropping tank 2.

[0049] like Figure 1 As shown, in some embodiments of this disclosure, the phosphorus pentachloride high-level tank 1 can also be configured as a cone shape.

[0050] In some embodiments of this disclosure, the gas generated by the reaction of phosphorus pentachloride and hydrofluoric acid, which includes phosphorus pentafluoride and hydrogen chloride, can be passed through a condenser and then through a demister, which is used to remove entrained droplets.

[0051] Those skilled in the art will understand that, in some embodiments of this disclosure, an appropriate number of condensers and / or an appropriate number of demisters can be selected as needed.

[0052] like Figure 1 As shown in some embodiments of this disclosure, the continuous preparation apparatus for hexafluorophosphate may further include a third packed tower 8. The liquid inlet of the third packed tower 8 is connected to a hydrofluoric acid storage tank and / or a hydrofluoric acid transfer tank, and the liquid outlet of the third packed tower 8 is connected to the inlet of the phosphorus pentafluoride preparation vessel 3 for feeding hydrofluoric acid into the phosphorus pentafluoride preparation vessel 3. The gas outlet of the third packed tower 8 is connected to a condenser at the top of the third packed tower (e.g., condenser 13a at the top of the third packed tower), and the gas inlet of the third packed tower 8 is connected to the phosphorus pentafluoride preparation vessel 3. Feeding the phosphorus pentafluoride preparation vessel 3 using the third packed tower 8 not only washes the sublimated phosphorus pentachloride, allowing the phosphorus pentachloride to react fully with the hydrofluoric acid, but also cools the mixed gas exiting the phosphorus pentafluoride preparation vessel 3.

[0053] like Figure 1 As shown, in some embodiments of this disclosure, the third packed tower top condenser may include two third packed tower top condensers 13a and 13b connected in sequence.

[0054] like Figure 1 As shown, in some embodiments of this disclosure, the continuous preparation apparatus for hexafluorophosphate may further include a third packed column top demister 14, and a third packed column top condenser (e.g., Figure 1 The third packed tower top condensers 13a and 13b are connected, and the gas outlet of the third packed tower top demister 14 is connected to the primary reactor 6. The gas discharged from the phosphorus pentafluoride preparation reactor 3 flows sequentially through the third packed tower top condenser 13a, the third packed tower top condenser 13b, and the third packed tower top demister 14. The gas outlet of the third packed tower top demister 14 is connected to the gas inlet of the primary reactor 6.

[0055] like Figure 1 As shown, in some embodiments of this disclosure, the condensate outlets of the third packed tower top condenser 13a and the third packed tower top condenser 13b can be connected to the feed inlet of the phosphorus pentafluoride preparation reactor 3. In other embodiments, the condensate outlets of the third packed tower top condenser 13a and the third packed tower top condenser 13b can be connected to the liquid feed inlet of the third packed tower 8. For example, in some embodiments of this disclosure, the liquid returning from the third packed tower top demister 14 passes sequentially through the third packed tower top condenser 13a and the third packed tower top condenser 13b, and flows back into the phosphorus pentafluoride preparation reactor 3 together with the condensate of the third packed tower 8.

[0056] Those skilled in the art will understand that, although Figure 2 Only two third-packed column top condensers (third-packed column top condenser 13a, third-packed column top condenser 13b) and one third-packed column top demister 14 are shown, but this is only exemplary. The gas outlet of the phosphorus pentafluoride preparation vessel 3 may also be connected to other numbers of third-packed column top condensers and / or third-packed column top demisters for treating the gas discharged from the phosphorus pentafluoride preparation vessel 3.

[0057] In some embodiments of this disclosure, the continuous preparation apparatus for hexafluorophosphate may further include an exhaust gas treatment device (not shown in the figures) for treating the exhaust gas.

[0058] In some embodiments of this disclosure, the lithium source may include lithium fluoride.

[0059] In some embodiments of this disclosure, the sodium source may include sodium fluoride or sodium chloride.

[0060] In some embodiments of this disclosure, the exhaust gas treatment device may include a condenser, a high-pressure distillation column, and a water absorption device connected in sequence.

[0061] In some embodiments of this disclosure, the gas discharged from the secondary reactor may include hydrogen fluoride gas and hydrogen chloride gas. After condensation and high-pressure distillation, the gas discharged from the secondary reactor can be used to obtain high-purity hydrogen chloride gas.

[0062] In some embodiments of this disclosure, the water absorption device may include a multi-stage ordinary water absorption tower and a multi-stage ultrapure water absorption tower. The gas inlet of the first stage of the multi-stage ordinary water absorption tower is connected to the gas outlet of the high-pressure distillation tower. The gas outlet of each stage of the ordinary water absorption tower is connected to the gas inlet of the next stage of the ordinary water absorption tower. The gas outlet of the last stage of the ordinary water absorption tower is connected to the gas inlet of the first stage of the ultrapure water absorption tower. The gas outlet of the last stage of the ultrapure water absorption tower is connected to a waste gas treatment system. Both the multi-stage ordinary water absorption tower and the multi-stage ultrapure water absorption tower include a liquid outlet, a self-circulating inlet connected to the liquid outlet, and a liquid inlet. The liquid inlet of the previous stage of the ordinary water absorption tower is connected to the liquid outlet of the next stage of the ordinary water absorption tower. The liquid inlet of the last stage of the ordinary water absorption tower is connected to an ordinary water storage tank. The liquid outlet of the first stage of the ordinary water absorption tower is connected to a hydrochloric acid storage tank. The liquid inlet of the previous stage of the ultrapure water absorption tower is connected to the liquid outlet of the next stage of the ultrapure water absorption tower. The liquid inlet of the last stage of the ultrapure water absorption tower is connected to an ultrapure water storage tank. The liquid outlet of the first stage of the ultrapure water absorption tower is connected to an electronic-grade hydrochloric acid storage tank.

[0063] In some embodiments of this disclosure, the gas discharged after high-pressure distillation is first subjected to a multi-stage conventional water absorption tower to obtain industrial-grade hydrochloric acid. The gas discharged after passing through at least a multi-stage conventional water absorption tower is then subjected to a multi-stage ultrapure water absorption tower to obtain electronic-grade hydrochloric acid. Figure 2 A schematic diagram of the structure of a water absorption device 100 according to some embodiments of the present disclosure is shown.

[0064] like Figure 2As shown, in some embodiments of this disclosure, the water absorption device 100 may include a first-stage ordinary water absorption tower 110 and a second-stage ordinary water absorption tower 120 connected in sequence, and a first-stage ultrapure water absorption tower 130, a second-stage ultrapure water absorption tower 140, a third-stage ultrapure water absorption tower 150, and a fourth-stage ultrapure water absorption tower 160 connected in sequence. The gas inlet 114 of the first-stage ordinary water absorption tower is connected to the gas outlet (not shown) of the high-pressure distillation column. The gas outlet 115 of the first-stage ordinary water absorption tower is connected to the gas inlet 124 of the second-stage ordinary water absorption tower. The gas outlet 125 of the second-stage ordinary water absorption tower is connected to the gas inlet 134 of the first-stage ultrapure water absorption tower. The gas outlet 135 of the first-stage ultrapure water absorption tower is connected to the gas inlet 144 of the second-stage ultrapure water absorption tower. The gas outlet 145 of the second-stage ultrapure water absorption tower is connected to the gas inlet 154 of the third-stage ultrapure water absorption tower. The gas outlet 155 of the third-stage ultrapure water absorption tower is connected to the gas inlet 164 of the fourth-stage ultrapure water absorption tower. The gas outlet 165 of the fourth-stage ultrapure water absorption tower is connected to the waste gas treatment system. The liquid inlet 113 of the first-stage ordinary water absorption tower is connected to the liquid outlet 121 of the second-stage ordinary water absorption tower 120. The liquid inlet 123 of the second-stage ordinary water absorption tower is connected to an ordinary water storage tank (not shown in the figure). The liquid outlet 111 of the first-stage ordinary water absorption tower is connected to a hydrochloric acid storage tank (not shown in the figure). The liquid inlet 133 of the first-stage ultrapure water absorption tower is connected to the liquid outlet 141 of the second-stage ultrapure water absorption tower 140. The liquid inlet 143 of the second-stage ultrapure water absorption tower is connected to the liquid outlet 151 of the third-stage ultrapure water absorption tower. The liquid inlet 153 of the third-stage ultrapure water absorption tower is connected to the liquid outlet 161 of the fourth-stage ultrapure water absorption tower 160. The liquid inlet 163 of the fourth-stage ultrapure water absorption tower is connected to an ultrapure water storage tank (not shown in the figure). The liquid outlet 131 of the first-stage ultrapure water absorption tower 130 is connected to an electronic-grade hydrochloric acid storage tank (not shown in the figure).

[0065] In some embodiments of this disclosure, the self-circulation inlet 112 of the first-stage ordinary water absorption tower is connected to the liquid outlet 111 of the first-stage ordinary water absorption tower; the self-circulation inlet 122 of the second-stage ordinary water absorption tower is connected to the liquid outlet 121 of the second-stage ordinary water absorption tower; the self-circulation inlet 132 of the first-stage ultrapure water absorption tower is connected to the liquid outlet 131 of the first-stage ultrapure water absorption tower; the self-circulation inlet 142 of the second-stage ultrapure water absorption tower is connected to the liquid outlet 141 of the second-stage ultrapure water absorption tower; the self-circulation inlet 152 of the third-stage ultrapure water absorption tower is connected to the liquid outlet 151 of the third-stage ultrapure water absorption tower; and the self-circulation inlet 162 of the fourth-stage ultrapure water absorption tower is connected to the liquid outlet 161 of the second-stage ultrapure water absorption tower.

[0066] Those skilled in the art will understand that valves and other components can also be installed on the connecting pipelines between different levels of absorption towers.

[0067] In some embodiments of this disclosure, when the concentration of hydrofluoric acid in the absorbent in the first-stage ordinary water absorption tower 110 reaches a preset value, the first-stage ordinary water absorption tower stops self-circulation and transfers material outward. At this time, the absorbent in the second-stage ordinary water absorption tower 120 is transferred into the first-stage ordinary water absorption tower 110, and the second-stage ordinary water absorption tower 120 is replenished with fresh ordinary water.

[0068] In some embodiments of this disclosure, when the absorbent in the first-stage ultrapure water absorption tower 130 is saturated with hydrochloric acid, the first-stage ultrapure water absorption tower stops self-circulation and begins to transfer material outwards. At this time, the absorbent in the second-stage ultrapure water absorption tower 140 is transferred into the first-stage ultrapure water absorption tower 130, the absorbent in the third-stage ultrapure water absorption tower 150 is transferred into the second-stage ultrapure water absorption tower 140, the absorbent in the fourth-stage ultrapure water absorption tower 160 is transferred into the third-stage ultrapure water absorption tower 150, and fresh ultrapure water is added to the fourth-stage ultrapure water absorption tower 160.

[0069] In some embodiments of this disclosure, ordinary water may be tap water. Ultrapure water has a resistivity ≥18.2 MΩ*cm.

[0070] The absorbent liquid at each stage is recycled through inter-stage transfer, maximizing the utilization of the absorbent liquid that has absorbed hydrofluoric acid, reducing the consumption of new absorbent liquid (such as ultrapure water) and the generation of wastewater, lowering treatment costs, and achieving resource recovery. The self-circulation of each absorption tower enables resource recycling and can be used for the absorption of hydrogen chloride gas in each absorption tower.

[0071] Those skilled in the art will understand that ​ This is merely an example. A multi-stage ordinary water absorption tower may also include other numbers of ordinary water absorption towers, such as single-stage, triple-stage, or quadruple-stage towers, and a multi-stage ultrapure water absorption tower may also include other numbers of ultrapure water absorption towers, such as single-stage, double-stage, or quintuple-stage towers.

[0072] In some embodiments of this disclosure, whether hydrogen chloride has reached saturation can be determined, for example, by online analysis of hydrochloric acid concentration. Hydrogen chloride in the water or ultrapure water is considered saturated when the hydrochloric acid concentration no longer changes. In some embodiments of this disclosure, the absorbent can be replaced when the hydrofluoric acid concentration in the absorbent during the water absorption process reaches approximately 5%.

[0073] In some embodiments of this disclosure, combined with the two-stage preparation reactor process for hexafluorophosphate, under the condition that the tail gas discharged from the secondary reactor is basically free of phosphorus pentafluoride, the tail gas discharged from the secondary reactor is further treated by condensation, high-pressure distillation, water absorption and ultrapure water absorption, thereby achieving full treatment of the tail gas and graded recycling of resources, which greatly improves the recycling value of by-products.

[0074] The industrial-grade hydrochloric acid obtained in some embodiments of this disclosure may contain a small amount of hydrogen fluoride, and therefore can be applied in fields such as ore washing in mines and acidification in the chemical industry. The electronic-grade hydrochloric acid obtained in some embodiments of this disclosure can achieve a purity of over 99.99%, and can be applied in fields with high requirements for hydrochloric acid quality, such as semiconductors.

[0075] In some embodiments of this disclosure, the continuous preparation apparatus for hexafluorophosphate may further include a hexafluorophosphate transfer tank, a filtration device, and a crude hexafluorophosphate treatment device. The hexafluorophosphate transfer tank is connected to the material outlet of the primary reactor, the filtration device is connected to the hexafluorophosphate transfer tank, and the crude hexafluorophosphate treatment device is connected to the filtration device.

[0076] During their research, the inventors discovered that trace amounts of insoluble matter exist during the preparation of hexafluorophosphate. By filtering the material from the primary reactor and then transferring it to the hexafluorophosphate transfer tank, the purity of the final hexafluorophosphate can be improved.

[0077] In some embodiments of this disclosure, the crude hexafluorophosphate processing unit may include at least one vacuum concentration unit. In some embodiments of this disclosure, the vacuum concentration unit may include a scraped evaporator.

[0078] In some embodiments of this disclosure, the material in the reaction liquid transfer tank is concentrated under reduced pressure using a vacuum concentration device, such as a scraped evaporator, until crystals are completely precipitated, thus obtaining concentrated material.

[0079] In some embodiments of this disclosure, the crude hexafluorophosphate processing apparatus may further include at least one recrystallization unit for receiving concentrated material obtained after evaporation by a vacuum concentration unit, such as a scraped evaporator.

[0080] In some embodiments of this disclosure, the concentrated material can be recrystallized multiple times using supercritical carbon dioxide as a solvent. The mother liquor from each subsequent recrystallization is reused in the previous recrystallization, and fresh carbon dioxide is used for the final recrystallization. In some embodiments of this disclosure, the mother liquor from the first recrystallization is separated into carbon dioxide and hydrogen fluoride by high-pressure distillation for reuse.

[0081] The preparation of hexafluorophosphate using the hexafluorophosphate preparation apparatus of some embodiments of this disclosure includes the following steps:

[0082] Close the bottom valve of the high-level phosphorus pentachloride tank, open the equipment vent valve, add 3 tons of phosphorus pentachloride, and after adding the material, purge with nitrogen twice. Then close the vent valve and maintain a slight positive pressure inside the tank, not exceeding 0.05 MPa, for standby.

[0083] When the material level in the phosphorus pentachloride dropping tank reaches the conical section, open the high-level tank bottom valve and add material to the dropping tank until the upper limit of the sight glass is reached, then stop adding material. The material in the dropping tank is added to the phosphorus pentafluoride preparation kettle (cooled by jacketed refrigerant) via a propeller. The phosphorus pentachloride dropping rate is 965.08 kg / h.

[0084] Meanwhile, anhydrous hydrofluoric acid is fed from the distributor at the top of the packed tower and then into the phosphorus pentafluoride preparation reactor at a feed rate of 460.56 kg / h. The temperature of the phosphorus pentafluoride preparation reactor is controlled at around 20°C, for example, any temperature between 15°C and 40°C.

[0085] The vaporized hydrofluoric acid is condensed in a condenser and then flows back into the reactor. The phosphorus pentafluoride and hydrogen chloride gases produced by the reaction of phosphorus pentachloride and hydrofluoric acid are demisted by a demister after being condensed and then introduced into the primary reactor (cooled by jacketed refrigerant). During commissioning, a certain amount of lithium or sodium source (e.g., a hydrofluoric acid solution of lithium fluoride) is introduced into the primary reactor beforehand, followed by phosphorus pentafluoride feedstock, with the molar ratio of lithium fluoride to phosphorus pentafluoride controlled at approximately 0.9-1.15:1. After complete induction, this is used as the bottom feed. For example, a hydrofluoric acid solution containing approximately 240 kg of lithium fluoride is introduced. After the bottom feed in the primary reactor is prepared, or simultaneously with the preparation of the bottom feed in the primary reactor, a hydrofluoric acid solution of lithium fluoride is introduced into the secondary reactor. Once a certain liquid level is reached, the feed is transferred to the primary reactor, and continuous production begins.

[0086] During formal production, in the primary reactor, most of the phosphorus pentafluoride gas reacts with the lithium fluoride present in the reactor to produce lithium hexafluorophosphate. A small amount of unreacted phosphorus pentafluoride gas and hydrogen chloride gas that do not participate in the reaction are introduced into the secondary lithium hexafluorophosphate preparation reactor (cooled by a jacketed refrigerant) to continue the reaction, ensuring that the phosphorus pentafluoride gas reacts completely.

[0087] In the secondary preparation reactor of lithium hexafluorophosphate, the lithium fluoride hydrofluoric acid solution is fed at a rate of 3320 kg / h (containing 120 kg of lithium fluoride) from the top of the secondary preparation reactor. At the same time, the secondary preparation reactor of lithium hexafluorophosphate transfers material to the primary preparation reactor of lithium hexafluorophosphate at a rate of 3320 kg / h, and the primary preparation reactor of lithium hexafluorophosphate transfers material to the intermediate tank at a rate of 3900 kg / h. Insoluble substances are filtered out during the transfer process.

[0088] The tail gas discharged from the lithium hexafluorophosphate secondary preparation reactor, containing hydrogen chloride gas that does not participate in the reaction, is defoamed by a demister and then condensed in a condenser to remove most of the entrained hydrogen fluoride. The condensed hydrofluoric acid is then transferred to a hydrogen fluoride transfer tank for reuse. The hydrogen chloride gas containing a small amount of hydrogen fluoride is passed through a high-pressure distillation column to achieve a hydrogen fluoride content of less than 1 ppm. The high-purity hydrogen chloride is then absorbed by a conventional water absorption tower and an ultrapure water absorption tower to obtain ordinary hydrochloric acid and electronic-grade hydrochloric acid, respectively.

[0089] In some embodiments of this disclosure, the preparation of lithium fluoride is as follows: anhydrous hydrofluoric acid is added to the lithium fluoride preparation vessel, and then lithium fluoride is slowly added from the lithium fluoride high-level tank to dissolve in the hydrofluoric acid. The dissolution process is exothermic, and the jacket is cooled by passing a cooling medium to control the vessel temperature to be less than 20°C. The released heat causes the hydrofluoric acid to partially vaporize, and then it is condensed through a condenser. After the batching is completed, the material is transferred to a transfer vessel, and the transfer vessel conveys the material to the lithium hexafluorophosphate secondary preparation vessel at a rate of 3320 kg / h.

[0090] In some embodiments of this disclosure, the reaction liquid transferred to the transfer tank is pumped to three sets of 30 flat scrapers (jacketed and heated by steam) for vacuum concentration. When 2 / 3 of the original volume is evaporated, crystals precipitate. The scraper controls the temperature to within 60°C. The concentrated material enters the transfer kettle. When the liquid level of the material received in the transfer kettle reaches the upper limit, it is switched to another transfer kettle for receiving.

[0091] In some embodiments of this disclosure, the concentrated material undergoes three recrystallizations using supercritical carbon dioxide as a solvent. The mother liquor from the first recrystallization is separated and recovered by high-pressure distillation to recover carbon dioxide and hydrogen fluoride. The mother liquor from the third recrystallization is reused for the second recrystallization, and the mother liquor from the second recrystallization is reused for the first recrystallization. Fresh carbon dioxide is used for the third recrystallization. Those skilled in the art will understand that the fresh carbon dioxide referred to herein may include recovered, qualified carbon dioxide.

[0092] The obtained hexafluorophosphate product has a purity of 99.98%, with free acid (calculated as HF) content ≤0.0090%, moisture content ≤0.0020%, dimethyl carbonate (DMC) insoluble content ≤0.020%, and sulfate (as SO42-) content ≤0.020%. 2- (calculated as Cl) ≤5mg / kg, chloride (as Cl) - (Calculated) ≤2mg / kg.

[0093] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A continuous preparation apparatus for hexafluorophosphate, characterized in that, The reactor includes a primary reactor and a secondary reactor. The gas outlet of the primary reactor is connected to the secondary reactor to allow the exhaust gas from the primary reactor to enter the secondary reactor. The material outlet of the secondary reactor is connected to the liquid inlet of the primary reactor to transfer the material from the secondary reactor into the primary reactor. The primary reactor also includes a material outlet from which the crude hexafluorophosphate product obtained from the reaction is discharged. The secondary reactor also includes a gas outlet from which tail gas is discharged.

2. The continuous preparation apparatus for hexafluorophosphate according to claim 1, characterized in that, It also includes a second packed tower, the liquid inlet of which is connected to a lithium source or sodium source storage tank and / or a lithium source or sodium source transfer tank, the liquid outlet of which is connected to the liquid inlet of the secondary reactor; the gas inlet of which is connected to the gas outlet of the secondary reactor, and the gas outlet of which is connected to the top condenser of the second packed tower.

3. The continuous preparation apparatus for hexafluorophosphate according to claim 2, characterized in that, It also includes a second packed tower top demister, the gas inlet of which is connected to the gas outlet of the secondary reactor and / or the gas outlet of the second packed tower, the gas outlet of which is connected to the gas inlet of the second packed tower top demister, and the gas outlet of which discharges tail gas.

4. The continuous preparation apparatus for hexafluorophosphate according to claim 3, characterized in that, The condensate outlet of the second packed tower top condenser is connected to the liquid inlet of the secondary reactor and / or the liquid inlet of the second packed tower.

5. The continuous preparation apparatus for hexafluorophosphate according to claim 1, characterized in that, It also includes a first packed tower, the liquid inlet of which is connected to the liquid outlet of the first-stage reactor, and the liquid outlet of which is connected to the liquid inlet of the first-stage reactor; the gas inlet of which is connected to the gas outlet of the first-stage reactor, and the gas outlet of which is connected to the top condenser of the first packed tower.

6. The continuous preparation apparatus for hexafluorophosphate according to claim 5, characterized in that, It also includes a first packed tower top demister, the gas inlet of which is connected to the gas outlet of the primary reactor and / or the gas outlet of the first packed tower, the gas outlet of which is connected to the gas inlet of the first packed tower top demister, and the gas outlet of which is connected to the gas inlet of the secondary reactor.

7. The continuous preparation apparatus for hexafluorophosphate according to claim 6, characterized in that, The condensate outlet of the top condenser of the first packed tower is connected to the liquid inlet of the first-stage reactor and / or the liquid inlet of the first packed tower.

8. The continuous preparation apparatus for hexafluorophosphate according to claim 1, characterized in that, It also includes a phosphorus pentafluoride preparation vessel, the gas outlet of which is connected to the primary reaction vessel.

9. The continuous preparation apparatus for hexafluorophosphate according to claim 8, characterized in that, Also includes: A phosphorus pentachloride dropping vessel is used to drop phosphorus pentachloride into the phosphorus pentafluoride preparation vessel, and the phosphorus pentachloride dropping vessel is conical in shape. as well as A phosphorus pentachloride high-level tank is used to add phosphorus pentachloride into the phosphorus pentachloride dripping tank.

10. The continuous preparation apparatus for hexafluorophosphate according to claim 8, characterized in that, It also includes a third packed tower, the liquid inlet of which is connected to a hydrofluoric acid storage tank and / or a hydrofluoric acid transfer tank, and the liquid outlet of which is connected to the inlet of the phosphorus pentafluoride preparation reactor for feeding hydrofluoric acid into the phosphorus pentafluoride preparation reactor; the gas outlet of the third packed tower is connected to the top condenser of the third packed tower, and the gas inlet of the third packed tower is connected to the phosphorus pentafluoride preparation reactor.

11. The continuous preparation apparatus for hexafluorophosphate according to claim 10, characterized in that, It also includes a third packed tower top demister, which is connected to the third packed tower top condenser, and the gas outlet of the third packed tower top demister is connected to the first-stage reactor.

12. The continuous preparation apparatus for hexafluorophosphate according to claim 11, characterized in that, The condensate outlet of the top condenser of the third packed tower is connected to the feed inlet of the phosphorus pentafluoride preparation reactor and / or the liquid feed inlet of the third packed tower.

13. The continuous preparation apparatus for hexafluorophosphate according to claim 1, characterized in that, It also includes an exhaust gas treatment device, which comprises a demister, a condenser, a high-pressure distillation column, and a water absorption device connected in sequence.

14. The continuous preparation apparatus for hexafluorophosphate according to claim 1, characterized in that, The water absorption device includes a multi-stage ordinary water absorption tower and a multi-stage ultrapure water absorption tower. The gas inlet of the first stage of the multi-stage ordinary water absorption tower is connected to the gas outlet of the high-pressure distillation tower. The gas outlet of each stage of the ordinary water absorption tower is connected to the gas inlet of the next stage of the ordinary water absorption tower. The gas outlet of the last stage of the ordinary water absorption tower is connected to the gas inlet of the first stage of the ultrapure water absorption tower. The gas outlet of the last stage of the ultrapure water absorption tower is connected to the waste gas treatment system. Both the multi-stage ordinary water absorption tower and the multi-stage ultrapure water absorption tower include a liquid outlet, a self-circulating inlet connected to the liquid outlet, and a liquid inlet. The liquid inlet of the previous stage of the ordinary water absorption tower is connected to the liquid outlet of the next stage of the ordinary water absorption tower. The liquid inlet of the last stage of the ordinary water absorption tower is connected to an ordinary water storage tank. The liquid outlet of the first stage of the ordinary water absorption tower is connected to a hydrochloric acid storage tank. The liquid inlet of the previous stage of the ultrapure water absorption tower is connected to the liquid outlet of the next stage of the ultrapure water absorption tower. The liquid inlet of the last stage of the ultrapure water absorption tower is connected to an ultrapure water storage tank. The liquid outlet of the first stage of the ultrapure water absorption tower is connected to an electronic-grade hydrochloric acid storage tank.

15. The continuous preparation apparatus for hexafluorophosphate according to claim 1, characterized in that, It also includes a hexafluorophosphate transfer tank, a filtration device, and a crude hexafluorophosphate processing device. The hexafluorophosphate transfer tank is connected to the material outlet of the primary reactor, the filtration device is connected to the hexafluorophosphate transfer tank, and the crude hexafluorophosphate processing device is connected to the filtration device.

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