A hydrofluoric acid preparation apparatus

Abstract

This invention relates to a hydrofluoric acid preparation apparatus, comprising an oil bath heating device, a reaction vessel, a mounting frame, an anti-backflow tank, and an absorption tank. The reaction vessel, the anti-backflow tank, and the absorption tank are fixed on the mounting frame. The reaction vessel is partially immersed in the oil bath heating device. A first connecting pipe is provided between the gas outlet of the reaction vessel and the gas inlet of the anti-backflow tank, with one end of the first connecting pipe extending into the upper part of the anti-backflow tank. A second connecting pipe is provided between the absorption tank and the anti-backflow tank, with one end of the second connecting pipe extending into the lower part of the anti-backflow tank and the other end below the liquid surface of the absorption tank. This invention connects the reaction vessel, the anti-backflow tank, and the absorption tank together, and all the connecting devices and tank bodies are made of polytetrafluoroethylene (PTFE), which is corrosion-resistant and has good sealing properties. It can be used as a small-scale production device for theoretical research on the production of hydrofluoric acid using the fluorite method.

Description

Technical Field

[0001] This invention relates to the field of hydrofluoric acid preparation technology, and in particular to a hydrofluoric acid preparation apparatus. Background Technology

[0002] Hydrofluoric acid is a fundamental raw material in the fluorochemical industry, widely used in the preparation of fluorinated resins, refrigerants, cryolite, aluminum fluoride, and potassium fluoride. It has broad applications in glass etching, petroleum industry catalysts, semiconductor and chip manufacturing, and other fields. Currently, the main industrial method for preparing hydrofluoric acid is the fluorite-sulfuric acid process, which involves reacting fluorite with concentrated sulfuric acid to produce hydrofluoric acid.

[0003] The main process of the fluorite sulfuric acid process is as follows: sulfuric acid and fluorite powder in a certain ratio are added to a rotary reactor, and the furnace wall is heated. The hydrogen fluoride gas produced by the reaction passes through a crude distillation tower, a degassing tower, and a rectification tower to obtain high-purity anhydrous hydrogen fluoride. Currently, many scholars in China have conducted extensive research on the preparation of hydrofluoric acid using the fluorite sulfuric acid process. CN 112062091 A discloses an anhydrous hydrogen fluoride production equipment and its production process. The equipment includes a crusher, a closed conveyor, a preheater, a rotary reactor, a washing tower, a condensing tower, a rectification tower, and a degassing tower. This process preheats the reactants using a preheater before placing the preheated reactants into the rotary reactor for reaction, shortening the time the reactants spend in the rotary reactor and reducing the corrosion time of the rotary reactor. CN 112142009 A discloses a method and equipment for producing anhydrous hydrogen fluoride. The equipment mainly includes a fluidized bed reactor, a cyclone separator, a spiral reactor, a spray tower, a separation tank, and a condenser. The process uses ultrafine fluorite particles as raw materials, mixes water vapor, sulfur trioxide vapor, sulfuric acid vapor, and hydrogen fluoride gas, and fluidizes the solid particles to react. The fluidized layers at each level are in countercurrent contact, which greatly improves the mass and heat transfer efficiency and is suitable for processing low-grade fluorite powder.

[0004] Existing methods for producing hydrogen fluoride using rotary kilns can only utilize fluorite powder with a calcium fluoride content of approximately 97% and a particle size of around 100 mesh. Furthermore, other processes and equipment are mostly applicable to industrial production and cannot be used for theoretical research on small-scale equipment, significantly hindering research on the preparation of hydrofluoric acid from fluorite. Therefore, developing a small-scale fluorite-based hydrofluoric acid preparation device with good sealing properties that can simulate the internal environment of a rotary kiln is an urgent problem that needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a hydrofluoric acid preparation apparatus, a small-scale fluorite-based hydrofluoric acid preparation apparatus capable of simulating the internal environment of a rotary kiln, for experimental research.

[0006] To achieve the above objectives, the technical solution of the present invention is to provide a hydrofluoric acid preparation apparatus, comprising: an oil bath heating device, a reaction vessel, a fixing frame, an anti-backflow vessel, and an absorption vessel. The reaction vessel, the anti-backflow vessel, and the absorption vessel are fixed on the fixing frame. The reaction vessel is partially immersed in the oil bath heating device. A first connecting pipe is provided between the gas outlet pipe of the reaction vessel and the gas inlet end of the anti-backflow vessel. One end of the first connecting pipe extends into the anti-backflow vessel and is located at the upper part of the anti-backflow vessel. A second connecting pipe is provided between the absorption vessel and the anti-backflow vessel. One end of the second connecting pipe extends into the lower part of the anti-backflow vessel, and the other end is located below the liquid surface of the absorption vessel.

[0007] Furthermore, the oil bath heating device includes an oil bath pot and a heating furnace. The oil bath pot is placed on the heating furnace and is filled with silicone oil. The reaction vessel is partially immersed in the silicone oil.

[0008] Furthermore, the top of the reaction vessel is provided with a first sealing plug, and the gas outlet pipe of the reaction vessel is opened on the first sealing plug. The gas outlet end is connected to one end of the first connecting pipe through a hexagonal threaded pipe.

[0009] Furthermore, a magnetic stir bar is installed inside the reaction vessel.

[0010] Furthermore, the fixing frame includes a frame body and several clamps. The clamps are fixed to the frame body and are used to fix the reaction vessel, the anti-backflow vessel, the absorption vessel, and the secondary absorption vessel. The clamps fix the reaction vessel, the anti-backflow vessel, the absorption vessel, and the secondary absorption vessel at the same horizontal line.

[0011] Furthermore, the top of the anti-backflow can is provided with a second sealing plug, on which an air inlet and an air outlet are provided. The first connecting pipe extends into the anti-backflow can through the air inlet and is located at the upper part of the anti-backflow can, while the second connecting pipe extends into the anti-backflow can through the air outlet and is located at the lower part of the anti-backflow can.

[0012] Furthermore, the top of the absorption tank is provided with a third sealing plug, which has an air inlet and an air outlet. The second connecting pipe extends into the absorption tank through the air inlet and is located below the liquid surface of the absorption tank. The third connecting pipe extends into the absorption tank through the air outlet and is located above the liquid surface of the absorption tank. The absorption tank is filled with NaOH absorption liquid.

[0013] Furthermore, it also includes a primary absorption tank, which is fixed on the fixed frame. A third connecting pipe is provided between the secondary absorption tank and the primary absorption tank. One end of the third connecting pipe is above the liquid surface of the primary absorption tank, and the other end is below the liquid surface of the secondary absorption tank. An exhaust pipe is provided on the secondary absorption tank.

[0014] Furthermore, the secondary absorption tank is provided with a fourth sealing plug at the top, and the fourth sealing plug has an air inlet and an air outlet. The third connecting pipe extends into the secondary absorption tank through the air inlet and is located below the liquid surface of the secondary absorption tank. The exhaust pipe extends into the secondary absorption tank through the air outlet and is located above the liquid surface of the secondary absorption tank. The secondary absorption tank is filled with NaOH absorption liquid.

[0015] Furthermore, the reaction vessel, the fixing frame, the anti-backflow vessel, the absorption vessel, and the secondary absorption vessel are made of polytetrafluoroethylene.

[0016] Compared with the prior art, the hydrofluoric acid preparation apparatus provided by the present invention has the following beneficial effects:

[0017] The present invention proposes a hydrofluoric acid preparation device that connects a reaction vessel, an anti-backflow vessel, and an absorption vessel together. All the connecting devices and the vessel bodies are made of polytetrafluoroethylene, which is corrosion-resistant and has good sealing performance. It can be used as a small-scale production device for theoretical research on the production of hydrofluoric acid by the fluorite method. Attached Figure Description

[0018] Figure 1 This is a cross-sectional schematic diagram of a hydrofluoric acid preparation apparatus provided by the present invention;

[0019] Figure 2 for Figure 1 Schematic diagram of the structure of the intermediate reaction vessel, the fixed frame, the anti-backflow vessel, the absorption vessel, and the secondary absorption vessel;

[0020] Figure 3 This is an XRD diagram of another embodiment of a hydrofluoric acid preparation apparatus provided by the present invention;

[0021] In the diagram: 1-Oil bath heating device, 11-Oil bath pot, 12-Heating furnace, 2-Reaction vessel, 21-First sealing plug, 22-Magnetic stir bar, 3-Fixing frame, 31-Frame body, 32-Claw, 4-Anti-backflow vessel, 41-Second sealing plug, 5-Absorption vessel, 51-Third sealing plug, 6-Secondary absorption vessel, 61-Fourth sealing plug, 62-Exhaust pipe, 7-First connecting pipe, 8-Second connecting pipe, 9-Third connecting pipe. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0023] Please see Figure 1 , Figure 2 The first embodiment of the present invention provides a hydrofluoric acid preparation apparatus, which includes: an oil bath heating device 1, a reaction tank 2, a fixing frame 3, an anti-backflow tank 4, and an absorption tank 5. The reaction tank 2, the anti-backflow tank 4, and the absorption tank 5 are fixed on the fixing frame 3. The reaction tank 2 is partially immersed in the oil bath heating device 1. A first connecting pipe 7 is provided between the gas outlet pipe of the reaction tank 2 and the gas inlet end of the anti-backflow tank 4. One end of the first connecting pipe 7 extends into the anti-backflow tank 4 and is located at the upper part of the anti-backflow tank 4. A second connecting pipe 8 is provided between the absorption tank 5 and the anti-backflow tank 4. One end of the second connecting pipe 8 extends into the lower part of the anti-backflow tank 4, and the other end is located below the liquid surface of the absorption tank 5.

[0024] Before operating the reaction apparatus, fluorite, concentrated sulfuric acid, and a magnetic stirrer must be placed in the reaction vessel 2, and the NaOH absorbent solution must be placed in the absorption vessel 5. The entire reaction apparatus is then assembled sequentially from front to back and from top to bottom. During operation, the oil bath heating device 1 heats the reaction vessel 2 to 200-300°C. The generated gas is gradually absorbed through the anti-backflow vessel 4, the absorption vessel 5, and the secondary absorption vessel 6. The anti-backflow vessel 4 effectively prevents the absorbent solution in the absorption vessel 5 from being drawn back into the reaction vessel 2.

[0025] Specifically, the oil bath heating device 1 includes an oil bath pot 11 and a heating furnace 12. The oil bath pot 11 is placed on the heating furnace 12. The oil bath pot 11 is filled with silicone oil, and the reaction vessel 2 is partially immersed in the silicone oil.

[0026] Specifically, the top of the reaction vessel 2 is provided with a first sealing plug 21, and the gas outlet pipe of the reaction vessel 2 is opened on the first sealing plug 21. The gas outlet end is connected to one end of the first connecting pipe 7 through a hexagonal threaded pipe.

[0027] Specifically, the reaction vessel 2 is equipped with a magnetic stirrer 22, which can stir the materials in the reaction vessel 2 and accelerate the reaction of the materials in the reaction vessel 2.

[0028] Furthermore, the fixing frame 3 includes a frame body 31 and a plurality of clamps 32. The clamps 32 are fixed on the frame body 31 and are used to fix the reaction vessel 2, the anti-backflow vessel 4, and the absorption vessel 5. The clamps 32 fix the reaction vessel 2, the anti-backflow vessel 4, the absorption vessel 5, and the secondary absorption vessel 6 to the same horizontal line.

[0029] Specifically, the anti-backflow tank 4 is equipped with a second sealing plug 41 at its top. The second sealing plug 41 has an air inlet and an air outlet. The first connecting pipe 7 extends into the anti-backflow tank 4 through the air inlet and is located at the upper part of the anti-backflow tank 4. The second connecting pipe 8 extends into the anti-backflow tank 4 through the air outlet and is located at the lower part of the anti-backflow tank 4. In the event of backflow, the liquid in the absorption tank 5 and the secondary absorption tank 6 will only enter the lower part of the anti-backflow tank 4 and will not enter the reaction tank 2 through the first connecting pipe 7, thus providing a protective function.

[0030] Specifically, the inside of the anti-backflow can 4 is empty.

[0031] Specifically, the top of the absorption tank 5 is provided with a third sealing plug 51, which has an air inlet and an air outlet. The second connecting pipe 8 extends into the absorption tank 5 through the air inlet and is located below the liquid surface of the absorption tank 5. The third connecting pipe 9 extends into the absorption tank 5 through the air outlet and is located above the liquid surface of the absorption tank 5. The absorption tank 5 is filled with NaOH absorption liquid, which is used to absorb hydrogen fluoride gas generated by the reaction of fluorite and concentrated sulfuric acid.

[0032] Considering that the absorption tank 5 may not completely absorb the gas, the present invention also includes a secondary absorption tank 6. The secondary absorption tank 6 is fixed on the fixing frame 3, and a third connecting pipe 9 is provided between the secondary absorption tank 6 and the absorption tank 5. One end of the third connecting pipe 9 is above the liquid surface of the absorption tank 5, and the other end is below the liquid surface of the secondary absorption tank 6. An exhaust pipe is provided on the secondary absorption tank 6. The secondary absorption tank 6 is used to absorb the gas that the absorption tank 5 has not completely absorbed.

[0033] Specifically, the secondary absorption tank 6 is provided with a fourth sealing plug 61 at the top, and the fourth sealing plug 61 has an air inlet and an air outlet. The third connecting pipe 9 extends into the secondary absorption tank 6 through the air inlet and is located below the liquid surface of the secondary absorption tank 6. The exhaust pipe 62 extends into the secondary absorption tank 6 through the air outlet and is located above the liquid surface of the secondary absorption tank 6. The secondary absorption tank 6 is filled with NaOH absorption liquid, which is used to absorb hydrogen fluoride gas generated by the reaction of fluorite and concentrated sulfuric acid.

[0034] Furthermore, the reaction vessel 2, the first connecting pipe 7, the second connecting pipe 8, the third connecting pipe 9, the anti-backflow vessel 4, the absorption vessel 5, and the secondary absorption vessel 6 are made of polytetrafluoroethylene.

[0035] Before operating the reaction apparatus, fluorite, concentrated sulfuric acid, and a magnetic stirrer must be placed in the reaction vessel 2. NaOH absorbent solution is placed in the absorption vessel 5 and the secondary absorption vessel 6. The entire reaction apparatus is then assembled sequentially from front to back and from top to bottom. During operation, the oil bath heating device 1 heats the reaction vessel 2 to 200-300°C. The generated gas is gradually absorbed through the anti-backflow vessel 4, the absorption vessel 5, and the secondary absorption vessel 6. The anti-backflow vessel 4 effectively prevents the absorbent solution in the absorption vessel 5 and the secondary absorption vessel 6 from being drawn back into the reaction vessel 2.

[0036] The following are the results of the experiment conducted using this device:

[0037] Before operation, fluorite and concentrated sulfuric acid were placed in reaction vessel 2, with the molar ratio of fluorite to concentrated sulfuric acid maintained at approximately 1:2 to 1:6. The fluorite powder used had a particle size of -400 to 200 mesh and a calcium fluoride content of 90% to 97%. The reaction was carried out at atmospheric pressure at a reaction temperature of 200°C. After 8 hours of stable operation, XRD analysis was performed on samples of the waste residue discharged from the reaction vessel to determine its main components. Please see [link to relevant documentation]. Figure 3 The samples reacted for 4 hours and 8 hours were designated as Sample 1 and Sample 2, respectively. XRD test results showed that only gypsum phase was present in the discharged waste residue, and calcium fluoride could not be detected, indicating that fluorite reacted fully with concentrated sulfuric acid and the calcium fluoride conversion rate was almost 100%.

[0038] To further determine the time required for fluorite and concentrated sulfuric acid to fully react under these conditions, the reaction time was shortened from 8 hours to 4 hours under the same conditions. XRD analysis was performed on the waste residue after 4 hours of reaction. The results showed that the waste residue contained only gypsum phase and no calcium fluoride, indicating that at 200℃, fluorite and concentrated sulfuric acid with a molar ratio of 1:6 reacted fully within 4 hours.

[0039] The advantages of this invention are:

[0040] 1. The present invention proposes a hydrofluoric acid preparation device that connects a reaction tank, an anti-backflow tank, an absorption tank, and a secondary absorption tank together. All the connecting devices and tank bodies are made of polytetrafluoroethylene, which is corrosion-resistant and has good sealing performance. It can be used as a small-scale production device for theoretical research on the production of hydrofluoric acid by the fluorite method.

[0041] 2. The hydrofluoric acid preparation apparatus proposed in this invention uses an iron frame and a right-angle three-jaw clamp to fix the reaction vessel to the bottom of the oil bath. The anti-backflow vessel and two absorption vessels are placed at the same level as the reaction vessel using the iron frame and two-jaw clamp to prevent hydrogen fluoride gas leakage due to the vessel tipping over during the reaction.

[0042] 3. The hydrofluoric acid preparation apparatus proposed in this invention, by placing the reaction vessel in an oil bath containing silicone oil, can raise the temperature of the reaction vessel to 200-300°C, providing heat for the reaction of fluorite and concentrated sulfuric acid. Furthermore, a magnetic stir bar is installed at the bottom of the reaction vessel, which is in close contact with the vessel body. The stirring function of the oil bath can be used to fully stir and mix the fluorite and concentrated sulfuric acid, thereby increasing the generation rate of hydrogen fluoride gas.

[0043] 4. In the hydrofluoric acid preparation apparatus proposed in this invention, as the reaction proceeds, the generation rate of hydrogen fluoride gas gradually decreases. When the dissolution rate of hydrogen fluoride gas in the absorption tank exceeds the generation rate of hydrogen fluoride gas in the reaction tank, a certain pressure difference exists between the reaction tank and the absorption tank, causing backflow of the absorbent liquid in the absorption tank. By setting an empty tank with a short inlet pipe and a long outlet pipe between the reaction tank and the absorption tank, the backflow of NaOH solution from the two absorption tanks into the reaction tank can be prevented. Furthermore, the short inlet and long outlet design of the backflow prevention tank effectively prevents hydrogen fluoride gas leakage.

[0044] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the present invention.

Claims

1. A hydrofluoric acid preparation apparatus, characterized in that, include: The system includes an oil bath heating device, a reaction vessel, a mounting frame, an anti-backflow vessel, and an absorption vessel. The reaction vessel, the anti-backflow vessel, and the absorption vessel are fixed to the mounting frame. The reaction vessel is partially submerged in the oil bath heating device. A first connecting pipe is provided between the outlet pipe of the reaction vessel and the inlet pipe of the anti-backflow vessel. One end of the first connecting pipe extends into the anti-backflow vessel and is located at the upper part of the anti-backflow vessel. A second connecting pipe is provided between the absorption vessel and the anti-backflow vessel. One end of the second connecting pipe extends into the lower part of the anti-backflow vessel, and the other end is located below the liquid surface of the absorption vessel. A second sealing plug is provided at the top of the anti-backflow vessel. The second sealing plug has an inlet and an outlet. The first connecting pipe extends into the anti-backflow vessel through the inlet and is located at the upper part of the anti-backflow vessel. The second connecting pipe extends into the anti-backflow vessel through the outlet and is located at the lower part of the anti-backflow vessel. The reaction vessel is equipped with a magnetic stir bar.

2. The hydrofluoric acid preparation apparatus according to claim 1, characterized in that: The oil bath heating device includes an oil bath pot and a heating furnace. The oil bath pot is placed on the heating furnace and is filled with silicone oil. The reaction vessel is partially immersed in the silicone oil.

3. The hydrofluoric acid preparation apparatus according to claim 1, characterized in that: The top of the reaction vessel is provided with a first sealing plug, and the gas outlet pipe of the reaction vessel is opened on the first sealing plug. The gas outlet pipe is connected to one end of the first connecting pipe through a hexagonal threaded pipe.

4. The hydrofluoric acid preparation apparatus according to claim 1, characterized in that: It also includes a secondary absorption tank, which is fixed on the fixed frame. A third connecting pipe is provided between the secondary absorption tank and the absorption tank. One end of the third connecting pipe is above the liquid surface of the absorption tank, and the other end is below the liquid surface of the secondary absorption tank. An exhaust pipe is provided on the secondary absorption tank.

5. The hydrofluoric acid preparation apparatus as described in claim 4, characterized in that: The fixing frame includes a frame body and several clamps. The clamps are fixed to the frame body and are used to fix the reaction vessel, the anti-backflow vessel, the absorption vessel, and the secondary absorption vessel. The clamps fix the reaction vessel, the anti-backflow vessel, the absorption vessel, and the secondary absorption vessel at the same horizontal line.

6. The hydrofluoric acid preparation apparatus according to claim 4, characterized in that: The top of the absorption tank is provided with a third sealing plug, which has an air inlet and an air outlet. The second connecting pipe extends into the absorption tank through the air inlet and is located below the liquid surface of the absorption tank. The third connecting pipe extends into the absorption tank through the air outlet and is located above the liquid surface of the absorption tank. The absorption tank is filled with NaOH absorption liquid.

7. The hydrofluoric acid preparation apparatus according to claim 4, characterized in that: The secondary absorption tank is provided with a fourth sealing plug at the top, and the fourth sealing plug has an air inlet and an air outlet. The third connecting pipe extends into the secondary absorption tank through the air inlet and is located below the liquid surface of the secondary absorption tank. The exhaust pipe extends into the secondary absorption tank through the air outlet and is located above the liquid surface of the secondary absorption tank. The secondary absorption tank is filled with NaOH absorption liquid.

8. The hydrofluoric acid preparation apparatus as described in claim 4, characterized in that: The reaction vessel, the mounting frame, the anti-backflow vessel, the absorption vessel, and the secondary absorption vessel are all made of polytetrafluoroethylene.

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