Continuous production process of sodium hexafluorophosphate

Abstract

The present invention discloses a continuous production process of sodium hexafluorophosphate, which relates to the technical field of preparation of halogen-containing phosphates. The production system adopted therein includes: a first reaction kettle, a second reaction kettle, a third reaction kettle, a condenser, a mother liquor tank, a gas-producing intermediate tank, a tubular reactor, a reaction crystallizer, a continuous rotary table vacuum filter, a continuous rake dryer and a finished product tank. High-purity hydrogen fluoride solution is provided to the second reaction kettle and the third reaction kettle through the first reaction kettle. The present invention goes through the synthesis process of phosphorus pentafluoride, the synthesis process of sodium hexafluorophosphate, the crystallization and drying process and the recovery process, solves the technical problem of discontinuous reaction crystallization of sodium hexafluorophosphate in the prior art, and the whole reaction process can be controlled by an automatic control system, solving the technical problems such as low efficiency, high energy consumption, heavy pollution and poor product quality existing in the traditional batch intermittent production process of sodium hexafluorophosphate.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of halogen-containing phosphates, and particularly relates to a continuous production process of sodium hexafluorophosphate. Background Art

[0002] At present, in most fields such as new energy, chemical industry and pharmaceuticals, the traditional batch intermittent production process is mainly adopted. The intermittent production process has technical problems such as low process efficiency, high energy consumption, heavy pollution and poor product quality. In response to this, the main ways to change this intermittent production process are: adding new equipment, new process design amplification and process regulation, but there are still technical problems such as large floor area and a large number of required operators.

[0003] In the continuous production process, both the feeding and discharging are kept continuous. The continuous process effectively reduces the production cost by eliminating the downtime and reducing the pollution risk, and promotes the continuous control of the reaction and crystal quality under steady state, thereby improving the product quality and stability. The continuous process can reduce the number of equipment and floor area, reduce the number of manual workers while realizing automated and intelligent operation, and greatly improve the production efficiency.

[0004] At present, the preparation methods of sodium hexafluorophosphate in the existing technologies mainly adopt the intermittent production. For example, the application No. 201711395637.5 discloses a preparation method of sodium hexafluorophosphate, which includes reacting a hexafluorophosphate with a sodium source in a reaction medium to obtain a crude solution of sodium hexafluorophosphate, removing any unreacted raw materials contained therein, and performing recrystallization to obtain the sodium hexafluorophosphate. The application No. 202111031883.9 discloses a preparation method of sodium hexafluorophosphate, which includes the following steps: (1) under an inert atmosphere, dissolving hexafluorophosphoric acid in pure water to prepare an aqueous solution of hexafluorophosphoric acid, and then slowly dropping pyridine into the aqueous solution of hexafluorophosphoric acid for reaction. After the reaction is completed, vacuum filtration, washing and drying are carried out to obtain pyridine hexafluorophosphate; (2) reacting the pyridine hexafluorophosphate obtained in step (1) with a sodium source in a solution. After the reaction is completed, it is cooled to room temperature, filtered, vacuum dried and recrystallized to obtain sodium hexafluorophosphate.

[0005] The preparation methods of sodium hexafluorophosphate in the above existing technologies all adopt the intermittent production process, and have technical problems such as low production efficiency, long reaction time and more impurity ions.

[0006] It can be seen that the existing technologies need to be further improved. Summary of the Invention

[0007] The purpose of the present invention is to provide a continuous production process for sodium hexafluorophosphate. During the production process, an inert gas is used for protection, which can effectively prevent the product from contacting with air. Automated feeding and reaction are adopted to achieve the continuity of the production process.

[0008] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0009] A continuous production process for sodium hexafluorophosphate, and the production system adopted therein includes: a first reaction kettle, a second reaction kettle, a third reaction kettle, a condenser, a mother liquor tank, a gas-producing intermediate tank, a tubular reactor, a reaction crystallizer, a continuous rotary table vacuum filter, a continuous rake dryer, and a finished product tank;

[0010] The first reaction kettle is used for refining hydrogen fluoride solution and respectively conveying high-purity hydrogen fluoride solution to the second reaction kettle and the third reaction kettle; the second reaction kettle is used for preparing phosphorus pentafluoride gas, and the third reaction kettle is used for dissolving sodium fluoride solid;

[0011] The condenser is used for removing impurities from the phosphorus pentafluoride gas prepared in the second reaction kettle;

[0012] The gas-producing intermediate tank is used for storing the phosphorus pentafluoride gas after impurity removal by the condenser;

[0013] The tubular reactor is used for receiving the hydrogen fluoride solution containing sodium fluoride from the third reaction kettle and the phosphorus pentafluoride gas from the gas-producing intermediate tank;

[0014] The mother liquor tank is used for receiving the sodium hexafluorophosphate solution generated after the reaction in the tubular reactor;

[0015] The reaction crystallizer is used for receiving the mother liquor obtained by heating and concentrating the mother liquor from the mother liquor tank;

[0016] The continuous rotary table vacuum filter is used for receiving the sodium hexafluorophosphate solution processed by the reaction crystallizer;

[0017] The continuous rake dryer is used for receiving the sodium hexafluorophosphate crystals from the continuous rotary table vacuum filter;

[0018] The finished product tank is connected to the continuous rake dryer;

[0019] The production process includes the following steps:

[0020] Step 1: Refine the hydrogen fluoride solution through the first reaction kettle to obtain high-purity hydrogen fluoride solution;

[0021] Step 2: Introduce a certain proportion of phosphorus pentachloride into the second reactor, and add high-purity hydrogen fluoride solution to the second reactor. In the second reactor, phosphorus pentachloride reacts with the high-purity hydrogen fluoride solution to generate phosphorus pentafluoride gas. The phosphorus pentafluoride gas enters the condenser for impurity removal treatment, and the phosphorus pentachloride gas after impurity removal is introduced into the intermediate gas storage tank for storage;

[0022] Step 3: Introduce a certain proportion of sodium fluoride into the third reactor, and add high-purity hydrogen fluoride solution to the third reactor. In the third reactor, sodium fluoride is dissolved by the high-purity hydrogen fluoride solution to obtain a hydrogen fluoride solution containing sodium fluoride;

[0023] Step 4: Introduce the hydrogen fluoride solution containing sodium fluoride obtained in the third reactor and the phosphorus pentafluoride gas in the intermediate gas storage tank into a tubular reactor for reaction, and a sodium hexafluorophosphate solution is obtained after complete reaction;

[0024] Step 5: Introduce the sodium hexafluorophosphate solution obtained in Step 4 into a mother liquor tank, heat and concentrate it to remove excess hydrogen fluoride gas;

[0025] Step 6: The sodium hexafluorophosphate solution concentrated in Step 5 is continuously crystallized through a reaction crystallizer;

[0026] Step 7: After crystallization, it enters a continuous rotary table vacuum filter for continuous vacuum filtration to obtain sodium hexafluorophosphate crystals;

[0027] Step 8: The sodium hexafluorophosphate crystals enter a continuous rake dryer, and excess hydrogen fluoride gas is removed through the continuous rake dryer to obtain finished sodium hexafluorophosphate powder;

[0028] Step 9: The finished sodium hexafluorophosphate powder enters the finished product tank.

[0029] The beneficial technical effects directly brought by the above technical solution are:

[0030] By adopting the above production system, continuous production of sodium hexafluorophosphate can be realized. Through each component and their mutual cooperation relationship, the technical problem of discontinuous reaction crystallization of sodium hexafluorophosphate in the prior art is solved, and the whole reaction process can be controlled by an automatic control system, solving the technical problems such as low efficiency, high energy consumption, heavy pollution and poor product quality existing in the traditional batch intermittent production process of sodium hexafluorophosphate.

[0031] In the above continuous production process of sodium hexafluorophosphate, the first reaction kettle is kept connected to the second reaction kettle and the third reaction kettle through pipelines; the second reaction kettle is kept connected to the condenser and the gas-producing intermediate tank through pipelines; the third reaction kettle, the gas-producing intermediate tank and the tubular reactor are kept connected through pipelines; the tubular reactor is kept connected to the mother liquor tank through pipelines; the mother liquor tank is kept connected to the reaction crystallizer through pipelines; automatic valves are installed on all the connected pipelines, and the opening or closing of the automatic valves is controlled by an automatic control system.

[0032] In the above continuous production process of sodium hexafluorophosphate, in step two, phosphorus pentachloride is in excess relative to the high-purity hydrogen fluoride solution.

[0033] In the above continuous production process of sodium hexafluorophosphate, in step three, the molar ratio of sodium fluoride to the high-purity hydrogen fluoride solution is 1:10, the reaction temperature in the third reaction kettle is 0 - 10°C, and the reaction time is 1 - 6 h.

[0034] In the above continuous production process of sodium hexafluorophosphate, in step four, in the tubular reactor, the reaction temperature is 5 - 15°C, and the heating time is 1 - 5 h.

[0035] In the above continuous production process of sodium hexafluorophosphate, in step five, the heating temperature is 100°C - 140°C, the heating time is 4 - 8 h, and nitrogen purging is used to remove water vapor and other impurities.

[0036] In the above continuous production process of sodium hexafluorophosphate, in step six, gradient temperature-controlled crystallization is carried out in the reaction crystallizer.

[0037] In the above continuous production process of sodium hexafluorophosphate, in step seven, the pressure in the continuous rotary table vacuum filter is -0.10 - 0.00 Mpa, and the mother liquor obtained after filtration is recycled to the third reaction kettle and used for preparing the sodium hexafluorosulfate solution.

[0038] In the above continuous production process of sodium hexafluorophosphate, in step eight, the drying temperature of the continuous rake dryer is 70 - 90°C, and the excess hydrogen fluoride gas is removed by the continuous rake dryer; the first reaction kettle, the second reaction kettle, the third reaction kettle, the mother liquor tank, the gas-producing intermediate tank and the continuous rotary table vacuum filter are all equipped with stirring devices, pressure gauges and thermometers.

[0039] The above continuous production process of sodium hexafluorophosphate, wherein the reaction crystallizer is a continuous reaction crystallizer, which is composed of a series of reaction crystallizer monomers in series. The connecting pipe between adjacent reaction crystallizer monomers is a bent pipe; each reaction crystallizer monomer is provided with an independent heat exchange system, and the continuous reaction crystallizer is controlled in temperature by sections through the TCU temperature control system; the feeding and discharging of the continuous reaction crystallizer are controlled by an automatic control system.

[0040] Compared with the prior art, the present invention brings the following beneficial technical effects:

[0041] (1) In the continuous production process of sodium hexafluorophosphate of the present invention, by adopting the above production system, the finished powdered sodium hexafluorophosphate is prepared through the synthesis of phosphorus pentafluoride, the synthesis of sodium hexafluorophosphate, crystallization drying and recovery processes in sequence. During the production process, continuous production is adopted throughout. Especially during the feeding and discharging processes, continuous operation is maintained. The continuous process effectively reduces the production cost by eliminating downtime and reducing the pollution risk, and promotes the continuous control of the reaction and crystal quality under steady state, thereby improving the product quality and stability. The continuous production process of sodium hexafluorophosphate of the present invention can reduce the number of equipment and floor area, reduce the number of workers while realizing automatic and intelligent operation, and greatly improve the production efficiency.

[0042] (2) The reaction crystallizer of the present invention adopts a continuous reaction crystallizer, which has a high specific surface area, can achieve efficient heat and mass transfer, accurately control temperature and time, achieve a uniform residence time, improve the reaction selectivity and controllability, and reduce the occurrence of side reactions; make the crystal growth rate consistent, and continuously produce high-quality products with uniform properties.

[0043] (3) The continuous process of the present invention can realize automatic operation and real-time monitoring of the production process, improve the production safety performance and production efficiency; dynamic crystallization: the crystal form is good, not easy to agglomerate, and the purity is high.

[0044] (4) The continuous reaction crystallization module operates in a fully enclosed manner, reducing the leakage risk during the reaction crystallization process and ensuring the life and health safety of on-site operators.

[0045] (5) There is no magnification effect, which is convenient for industrial incubation and production expansion, reduces the number of equipment, personnel and floor area, and reduces the investment cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The present invention will be further described below with reference to the accompanying drawings:

[0047] Figure 1 It is the process flow chart of the continuous production process of sodium hexafluorophosphate of the present invention;

[0048] In the figure:

[0049] R1, the first reactor; R2, the second reactor; R3, the third reactor; Z, the condenser; R4, the mother liquor tank; R5, the continuous rotary table vacuum filter; R6, the intermediate gas production tank; B1, the tubular reactor; C1, the reaction crystallizer; D1, the continuous rake dryer; E1, the finished product tank; M, the stirring device; P, the pressure gauge; T, the thermometer. Detailed implementation manners

[0050] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application.

[0051] It can be understood that the connection relationship described in the present application refers to direct or indirect connection. For example, when A is connected to B, it can be either that A is directly connected to B or that A and B are indirectly connected through one or more other electrical components. For example, it can be that A is directly connected to C and C is directly connected to B, so that A and B are connected through C. It can also be understood that "A is connected to B" described in the present application can be either that A is directly connected to B or that A and B are indirectly connected through one or more other electrical components.

[0052] In the description of the present application, unless otherwise specified, " / " means "or". For example, A / B can represent A or B. The "and / or" herein is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone.

[0053] In the description of the present application, words such as "first" and "second" are only used to distinguish different objects, and do not limit the quantity and execution order, and the words such as "first" and "second" do not necessarily mean different. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion.

[0054] The raw materials required in the present invention can all be obtained through commercial channels.

[0055] Next, the technical solutions of the present application will be further described in detail in conjunction with the accompanying drawings.

[0056] As Figure 1 shown, in the continuous production process of sodium hexafluorophosphate of the present invention, the main components of the production system adopted are the first reactor R1, the second reactor R2, the third reactor R3, the condenser Z, the mother liquor tank R4, the continuous rotary table vacuum filter R5, the intermediate gas production tank R6, the tubular reactor B1, the reaction crystallizer C1, the continuous rake dryer D1 and the finished product tank E1.

[0057] The first reactor R1 is connected with an inlet pipeline and an outlet pipeline. The inlet pipeline is connected to a hydrogen fluoride source, and hydrogen fluoride is transported into the first reactor through the inlet pipeline and refined in the first reactor, specifically by means such as rectifying distillation, etc., to obtain a high-purity hydrogen fluoride solution.

[0058] The outlet pipeline of the first reactor is provided with multiple branches, which are respectively connected to the second reactor and the third reactor. Valves are arranged on each pipeline. For example, by opening or closing the valves, the high-purity hydrogen fluoride entering the second reactor and the third reactor can be controlled. Specifically, a flowmeter can also be arranged on the pipeline to facilitate monitoring the consumption of raw materials.

[0059] Phosphorus pentafluoride gas is prepared in the second reactor. The synthesis steps of phosphorus pentafluoride are as follows:

[0060] Phosphorus pentachloride is transported into the second reactor and reacts with high-purity hydrofluoric acid. The temperature is controlled at 0 - 19 °C and the pressure is controlled at 0.1 - 0.2 MPa. A mixed gas of phosphorus pentafluoride and hydrogen chloride is obtained by the reaction.

[0061] The reaction formula is: PCI5 + 5HF = PF5 + 5HCI

[0062] The outlet pipeline of the second reactor first passes through a condenser and then is connected to a gas production intermediate tank. The excess hydrogen fluoride and hydrogen chloride gases are removed through the condenser, and high-purity phosphorus pentafluoride is stored in the gas production intermediate tank.

[0063] The third reactor is used to dissolve sodium fluoride solid; specifically, the third reactor is connected to a sodium fluoride source through an inlet pipeline, sodium fluoride is added into the third reactor, and then the high-purity hydrogen fluoride in the first reactor is added into the third reactor to be mixed into a hydrofluoric acid solution containing high-purity sodium fluoride.

[0064] The high-purity phosphorus pentafluoride and the hydrofluoric acid solution containing high-purity sodium fluoride are mixed through a tee and enter a tubular reactor. The reaction temperature is controlled by a heating system and a TCU temperature control system to obtain a sodium hexafluorophosphate solution.

[0065] Reaction formula: PF5 + NaF → NaPF6

[0066] The sodium hexafluorophosphate solution prepared through the tubular reactor is introduced into a mother liquor tank, and the obtained mother liquor is heated and concentrated to remove the excess HF gas.

[0067] The outlet of the mother liquor tank is connected to a reaction crystallizer. The sodium hexafluorophosphate solution after concentration is crystallized through the reaction crystallizer, and a sectional temperature reduction is carried out by using a TCU temperature control system.

[0068] The continuous rotary table vacuum filter is connected to the reaction crystallizer and is used to receive the sodium hexafluorophosphate solution processed by the reaction crystallizer; the sodium hexafluorophosphate solution is continuously vacuum filtered in the continuous rotary table vacuum filter to form sodium hexafluorophosphate crystals, and the mother liquor generated by the filtration is returned to the third reaction kettle and used for the repeated preparation of the sodium hexafluorophosphate solution.

[0069] The continuous rake dryer is connected to the continuous rotary table vacuum filter and is used to receive the sodium hexafluorophosphate crystals from the continuous rotary table vacuum filter. The filtered sodium hexafluorophosphate crystals are transported to the continuous rake dryer to remove the excess hydrogen fluoride gas, and the finished sodium hexafluorophosphate powder is obtained.

[0070] The finished product tank is connected to the continuous rotary table vacuum filter, and the finished sodium hexafluorophosphate powder enters the finished product tank.

[0071] Each of the above components, such as the first reaction kettle, the second reaction kettle, the third reaction kettle, the mother liquor tank, the gas-producing intermediate tank, and the continuous rotary table vacuum filter, is equipped with a stirring device, a pressure gauge, and a thermometer. Those skilled in the art can decide whether to start the stirring device and how to control the pressure and temperature according to the temperature at which the reaction occurs and whether stirring is required. The present invention can also uniformly control the opening or closing of the stirring device through an automatic control system to achieve fully automated control.

[0072] The tubular reactor B1, which is used as a continuous reactor, can select multiple reaction pipes connected in parallel, and the length of the tubular reactor can be selected according to the actual situation.

[0073] The reaction crystallizer C1 is a continuous reaction crystallizer, and the continuous reaction crystallizer is composed of a plurality of reaction crystallizer monomers connected in series. The connecting pipe between adjacent reaction crystallizer monomers is a bent pipe; each reaction crystallizer monomer is provided with an independent heat exchange system, and the continuous reaction crystallizer is controlled for temperature in sections through the TCU temperature control system; the feeding and discharging of the continuous reaction crystallizer are controlled through an automatic control system.

[0074] The drying temperature of the continuous rake dryer is 70 - 90 °C, and the excess hydrogen fluoride gas is removed through the continuous rake dryer.

[0075] The pressure in the continuous rotary table vacuum filter is -0.10 to 0.00 Mpa, and the mother liquor obtained after filtration is recovered to the third reaction kettle and used for the preparation of the sodium hexafluorosulfate solution.

[0076] The continuous production process of sodium hexafluorophosphate of the present invention is described below, which mainly includes the synthesis process of phosphorus pentafluoride, the synthesis process of sodium hexafluorophosphate, the crystallization and drying process, and the recovery process.

[0077] Specifically, it includes the following steps:

[0078] Step 1: Refine the hydrogen fluoride solution through the first reactor to obtain a high-purity hydrogen fluoride solution;

[0079] Step 2: Introduce phosphorus pentachloride in a certain proportion into the second reactor, and add the high-purity hydrogen fluoride solution to the second reactor. In the second reactor, phosphorus pentachloride reacts with the high-purity hydrogen fluoride solution to generate phosphorus pentafluoride gas. The phosphorus pentafluoride gas enters the condenser for impurity removal treatment, and the phosphorus pentachloride gas after impurity removal is stored in the gas production intermediate tank;

[0080] Step 3: Introduce sodium fluoride in a certain proportion into the third reactor, and add the high-purity hydrogen fluoride solution to the third reactor. In the third reactor, dissolve sodium fluoride with the high-purity hydrogen fluoride solution to obtain a hydrogen fluoride solution containing sodium fluoride; the molar ratio of sodium fluoride to the high-purity hydrogen fluoride solution is 1:10, the reaction temperature in the third reactor is 0 - 10 °C, and the reaction time is 1 - 6 h;

[0081] Step 4: Add the hydrogen fluoride solution containing sodium fluoride obtained in the third reactor and the phosphorus pentafluoride gas in the gas production intermediate tank to the tubular reactor through a three-way joint for reaction. The reaction produces a sodium hexafluorophosphate solution, and nitrogen is used to blow off water and unreacted hydrogen fluoride; in the tubular reactor, the reaction temperature is 5 - 15 °C, the heating time is 1 - 5 h, and the gas generated after heating passes through the condenser and is refluxed to obtain a hydrogen fluoride solution;

[0082] Step 5: Pass the sodium hexafluorophosphate solution obtained in Step 4 into the mother liquor tank, heat and concentrate it to remove excess hydrogen fluoride gas;

[0083] Step 6: Continuously crystallize the sodium hexafluorophosphate solution obtained after gas washing in Step 5 through a reaction crystallizer;

[0084] Step 7: After crystallization, continuously vacuum filter it in a continuous rotary table vacuum filter to obtain sodium hexafluorophosphate crystals;

[0085] Step 8: The sodium hexafluorophosphate crystals enter a continuous rake dryer, and excess hydrogen fluoride gas is removed through the continuous rake dryer to obtain finished sodium hexafluorophosphate powder;

[0086] Step 9: The finished sodium hexafluorophosphate powder enters the finished product tank.

[0087] Example 1:

[0088] Step 1: Transport excessive phosphorus pentachloride to the second reactor and add the high-purity hydrogen fluoride solution to generate phosphorus pentafluoride gas. The generated gas enters the gas production intermediate tank through the condenser to remove impurity gases such as HCl and HF;

[0089] Step 2: Transfer 1 kg of sodium fluoride into the second reactor, and add 10 L of hydrofluoric acid solution to mix into a hydrofluoric acid solution containing high-purity sodium fluoride. Control the reaction temperature at about 10°C, and the reaction time is 1 - 6 hours;

[0090] Step 3: Pass phosphorus pentafluoride gas and the hydrofluoric acid solution containing high-purity sodium fluoride into the tubular reactor through a three-way joint, and use nitrogen to blow off water and unreacted hydrofluoric acid. Control the reaction temperature at about 10°C, and pass the heated gas through a condenser for reflux to obtain a dilute hydrofluoric acid solution;

[0091] Step 4: The generated sodium hexafluorophosphate solution enters the mother liquor tank. Heat and concentrate the obtained mother liquor. The heating temperature is 100°C - 140°C, and the heating time is 4 - 8 hours. Use nitrogen to purge to remove water vapor and other impurities, and recycle the excess HF gas through a fractionating tower;

[0092] Step 5: Crystallize the sodium hexafluorophosphate solution after concentration in Step 4 through a reaction crystallizer. If sodium hexafluorophosphate crystallization clogs or leaks, close the valve of the reaction material inlet pipe, open the valve of the nitrogen blowpipe to pass nitrogen to dredge the clogged pipeline, and separately recycle the material purged by nitrogen to the recovery system;

[0093] Step 6: Pass the sodium hexafluorophosphate solution in Step 5 into a continuous rotary table vacuum filter for continuous vacuum filtration. The pressure is -0.10 - 0.00 Mpa. The filtered mother liquor is recycled to the sodium fluoride dissolution tank to repeat the preparation of sodium hexafluorophosphate solution;

[0094] Step 7: Transfer the sodium hexafluorophosphate crystals in Step 6 to a continuous rake dryer to remove the excess HF gas to obtain the finished sodium hexafluorophosphate powder. Its drying temperature is 80°C. Preferably, recycle the excess HF gas through the dryer. Obtain 3.5 kg of product with a yield of 87.5%;

[0095] Step 8: Transfer the finished sodium hexafluorophosphate powder to the finished product tank. The test results show that the product purity is 99.74%, the moisture content is 13 ppm, and the free acid content is 56 ppm.

[0096] In the present invention, the valves on the pipeline can also be replaced by a tube chain conveyor. The reaction crystallizers mentioned in the present invention are all continuous reaction crystallizers; the tubular reactors mentioned in the present invention are all continuous tubular reactors.

[0097] Those of ordinary skill in the art of this technology should recognize that the above embodiments are only used to illustrate the present application, rather than to limit the present application. As long as within the scope of the substantial spirit of the present application, appropriate changes and variations made to the above embodiments fall within the scope claimed by the present application.

Claims

1. A continuous production process of sodium hexafluorophosphate, characterized in that, The production system adopted by it includes: a first reactor, a second reactor, a third reactor, a condenser, a mother liquor tank, a gas-producing intermediate tank, a tubular reactor, a reaction crystallizer, a continuous rotary table vacuum filter, a continuous rake dryer, and a finished product tank; The said first reactor is used for refining hydrogen fluoride solution and respectively conveying high-purity hydrogen fluoride solution to the second reactor and the third reactor; the said second reactor is used for preparing phosphorus pentafluoride gas, and the said third reactor is used for dissolving sodium fluoride solid; The said condenser is used for removing impurities from the phosphorus pentafluoride gas prepared in the second reactor; The said gas-producing intermediate tank is used for storing the phosphorus pentafluoride gas after impurity removal by the condenser; The said tubular reactor is used for receiving the hydrogen fluoride solution containing sodium fluoride from the third reactor and the phosphorus pentafluoride gas from the gas-producing intermediate tank; The said mother liquor tank is used for receiving the sodium hexafluorophosphate solution generated after the reaction in the tubular reactor; The said reaction crystallizer is used for receiving the mother liquor obtained by heating and concentrating the mother liquor from the mother liquor tank; the said reaction crystallizer is a continuous reaction crystallizer, and the continuous reaction crystallizer is composed of a plurality of reaction crystallizer monomers connected in series, and the connecting pipe between adjacent reaction crystallizer monomers is a bent pipe; each reaction crystallizer monomer is provided with an independent heat exchange system, and the continuous reaction crystallizer is controlled for temperature in sections through the TCU temperature control system; the feeding and discharging of the continuous reaction crystallizer are controlled by the automatic control system; The said continuous rotary table vacuum filter is used for receiving the sodium hexafluorophosphate solution processed by the reaction crystallizer; The said continuous rake dryer is used for receiving the sodium hexafluorophosphate crystals from the continuous rotary table vacuum filter; The said finished product tank is connected to the continuous rake dryer; The said production process includes the following steps: Step 1, refining hydrogen fluoride solution through the first reactor to obtain high-purity hydrogen fluoride solution; Step 2, introducing a certain proportion of phosphorus pentachloride into the said second reactor, and adding high-purity hydrogen fluoride solution to the second reactor. In the second reactor, phosphorus pentachloride reacts with high-purity hydrogen fluoride solution to generate phosphorus pentafluoride gas, and the phosphorus pentafluoride gas enters the said condenser for impurity removal treatment. After the impurity removal is completed, the phosphorus pentachloride gas is introduced into the gas-producing intermediate tank for storage; Step 3, introducing a certain proportion of sodium fluoride into the said third reactor, and adding high-purity hydrogen fluoride solution to the third reactor. In the third reactor, sodium fluoride is dissolved by high-purity hydrogen fluoride solution to obtain a hydrogen fluoride solution containing sodium fluoride; Step 4, introducing the hydrogen fluoride solution containing sodium fluoride obtained in the third reactor and the phosphorus pentafluoride gas in the gas-producing intermediate tank into the tubular reactor for reaction, and completely reacting to obtain a sodium hexafluorophosphate solution; Step 5, introducing the sodium hexafluorophosphate solution obtained in Step 4 into the mother liquor tank, heating and concentrating and removing the excess hydrogen fluoride gas; Step 6, introducing the sodium hexafluorophosphate solution concentrated in Step 5 into the reaction crystallizer for continuous crystallization; Step 7, after crystallization, entering the continuous rotary table vacuum filter for continuous vacuum filtration to obtain sodium hexafluorophosphate crystals; Step 8: The sodium hexafluorophosphate crystals enter a continuous rake dryer, and the excess hydrogen fluoride gas is removed by the continuous rake dryer to obtain the finished sodium hexafluorophosphate powder; Step 9: The finished sodium hexafluorophosphate powder enters the finished product tank.

2. The continuous production process of sodium hexafluorophosphate according to claim 1, characterized in that: The first reaction kettle is kept connected to the second reaction kettle and the third reaction kettle through pipelines; the second reaction kettle is kept connected to the condenser and the gas-producing intermediate tank through pipelines; the third reaction kettle, the gas-producing intermediate tank and the tubular reactor are kept connected through pipelines; the tubular reactor is kept connected to the mother liquor tank through pipelines; the mother liquor tank is kept connected to the reaction crystallizer through pipelines; automatic valves are provided on the connected pipelines, and the opening or closing of the automatic valves is controlled by an automatic control system.

3. The continuous production process of sodium hexafluorophosphate according to claim 1, characterized in that: In Step 2, phosphorus pentachloride is in excess relative to the high-purity hydrogen fluoride solution.

4. The continuous production process of sodium hexafluorophosphate according to claim 1, characterized in that: In Step 3, the molar ratio of sodium fluoride to the high-purity hydrogen fluoride solution is 1:10, the reaction temperature in the third reaction kettle is 0 - 10 °C, and the reaction time is 1 - 6 h.

5. The continuous production process of sodium hexafluorophosphate according to claim 1, characterized in that: In Step 4, in the tubular reactor, the reaction temperature is 5 - 15 °C, and the heating time is 1 - 5 h.

6. The continuous production process of sodium hexafluorophosphate according to claim 1, characterized in that: In Step 5, the heating temperature is 100 °C - 140 °C, the heating time is 4 - 8 h, and nitrogen purging is used to remove water vapor and other impurities.

7. The continuous production process of sodium hexafluorophosphate according to claim 1, characterized in that: In Step 6, gradient temperature-controlled crystallization is carried out in the reaction crystallizer.

8. The continuous production process of sodium hexafluorophosphate according to claim 1, characterized in that: In Step 7, the pressure in the continuous rotary table vacuum filter is -0.10 - 0.00 Mpa, and the mother liquor obtained after filtration is recycled to the third reaction kettle and used for preparing the sodium hexafluorosulfate solution.

9. The continuous production process of sodium hexafluorophosphate according to claim 1, characterized in that: In Step 8, the drying temperature of the continuous rake dryer is 70 - 90 °C, and the excess hydrogen fluoride gas is removed by the continuous rake dryer; the first reaction kettle, the second reaction kettle, the third reaction kettle, the mother liquor tank, the gas-producing intermediate tank and the continuous rotary table vacuum filter are all equipped with stirring devices, pressure gauges and thermometers.

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