Method and system for extracting high purity potassium fluoride solution

Abstract

The present application relates to a kind of method for extracting high-purity potassium fluoride solution and extraction system uses pre-dispensing, splitting fluorination, quenching absorption, spray absorption, tail gas purification five-step method, extracts high-purity potassium fluoride solution (including acid and alkaline two kinds), realizes waste gas liquid recycling and environmental protection standard discharge after use.

Description

Technical Field

[0001] This invention relates to the field of high-purity potassium fluoride solution extraction technology, and in particular to a method and extraction system for extracting high-purity potassium fluoride solution. Background Technology

[0002] Hydrofluoroethers (HFLEs) are high-performance fluorinated electronic chemicals. Their production generates hazardous waste, primarily composed of HFLEs and their high-boiling-point components, ethanol, potassium fluoride, potassium hydroxide, and water. This waste is mainly liquid with a small amount of gas. Current methods for treating HFLE waste gas and liquid involve distillation to avoid environmental pollution. However, after distillation, useful substances are mixed with impurities, making resource utilization difficult. Therefore, it is essential to research and develop a method for extracting high-purity potassium fluoride solution from HFLE waste gas and liquid. Summary of the Invention

[0003] (a) Technical problems to be solved

[0004] To address the aforementioned problems in the prior art, this invention provides a method and system for extracting high-purity potassium fluoride solution. This method allows organic matter to be completely decomposed at high temperatures, resulting in a high-purity potassium fluoride solution. The remaining fluorine is absorbed as hydrogen fluoride, resulting in a pure solution free of organic impurities. This method achieves resource decomposition and recovery. Compared with current recovery methods such as distillation, this innovative decomposition and fluorination method yields a high-purity potassium fluoride solution free of organic impurities, fully recovering and utilizing fluorine resources, reducing wastewater discharge, and promoting environmental protection. Furthermore, it significantly reduces production costs, demonstrating excellent environmental benefits and economic value.

[0005] (II) Technical Solution

[0006] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0007] A method for extracting high-purity potassium fluoride solution includes the following steps;

[0008] A1. Pre-mixing: The waste liquid is centrally stored in a storage tank. Before pyrolysis, an appropriate amount of potassium hydroxide is added according to the composition of potassium fluoride and potassium hydroxide in the residual liquid, and the excess fluoride ratio is controlled to be 1.2 to 1.5. Then methanol is added to adjust the viscosity of the liquid.

[0009] A2. Pyrolysis and Fluorination: The waste liquid is transported to the pyrolysis unit. After oxygenation by air, the waste liquid is metered into the pyrolysis chamber by a liquid spray gun located at the top of the pyrolysis unit. The waste liquid changes from liquid to gas at high temperature, and then burns and decomposes.

[0010] A3. Rapid Cooling Absorption: The flue gas generated by pyrolysis enters the segmented cooling mechanism through the overflow weir. A large amount of cooling water is sprayed out through the annular atomizer to fully contact the flue gas, and the temperature drops instantly from 1200℃ to 70℃, preventing the regeneration of dioxins. While spraying and cooling, the water absorbs hydrogen fluoride and potassium fluoride in the flue gas to form an acidic potassium fluoride solution (containing potassium fluoride, hydrogen fluoride, and water). The acidic potassium fluoride solution is transported to the acid cooler and then sprayed and absorbed again to reduce its solubility before being discharged into the storage tank.

[0011] A4. Interrupted Spray: A flow meter is installed on the acid outlet pipe of the acid cooler and a shut-off valve on the water outlet pipe of the water tank is interlocked. When the flow meter does not detect flow, the shut-off valve opens, and the water in the water tank is sent to the segmented cooling mechanism by high-pressure compressed air to protect the equipment.

[0012] A5. Spray absorption: The flue gas after rapid cooling absorption still contains acidic gases such as hydrogen fluoride. When it enters the absorption tower, the hydrogen fluoride is absorbed by spray water to form hydrofluoric acid. After replenishing part of the solution in the absorption tower, it is transported to the storage tank.

[0013] A6. Exhaust gas purification: After being washed with water in the absorption tower, the flue gas then passes through the alkaline scrubbing tower. In the alkaline scrubbing tower, potassium hydroxide solution is added to absorb the small amount of hydrogen fluoride in the flue gas, and the resulting potassium fluoride solution is discharged into the storage tank. After passing through the alkaline scrubbing tower, the flue gas is removed by a wet electrostatic precipitator and then led to the chimney by an induced draft fan for discharge.

[0014] An extraction system for extracting high-purity potassium fluoride solution includes a mixing mechanism, a spray pyrolysis mechanism, a segmented cooling mechanism, a flow interruption emergency mechanism, a fluoride recovery mechanism, and an exhaust gas purification mechanism.

[0015] The mixing mechanism includes a storage tank, a stirrer installed inside the storage tank, a waste liquid inlet pipe connected to the storage tank, a formula liquid inlet pipe, a bottom-mounted compressed air pipe, and a pressure gauge installed on the bottom-mounted compressed air pipe.

[0016] The spray pyrolysis mechanism includes a pyrolysis chamber, a combined pyrolyzer disposed above the pyrolysis chamber, and a fire control air box connected to the combined pyrolyzer; the fire control air box is connected to the combined pyrolyzer via a fire control air duct; the combined pyrolyzer includes a gas spray gun, a liquid spray gun, a large fire incinerator, and a persistent flame gun; the liquid spray gun is connected to a storage tank.

[0017] The segmented cooling mechanism is connected to the bottom of the pyrolysis chamber; the segmented cooling mechanism includes an overflow weir connected to the pyrolysis chamber, an annular atomizer located below the overflow weir, and an acid cooler located below the annular atomizer and connected to the annular atomizer; two or more layers of annular atomizers are arranged between the overflow weir and the storage tank; the annular atomizer includes 12-16 spray guns, arranged in 3-4 layers.

[0018] The segmented cooling mechanism also includes a graphite inner wall between the annular atomizer and the overflow weir, and a cooling circuit connecting the storage tank and the acid cooler; the cooling circuit includes two parallel conveying circuits; one conveying circuit conveys acidic potassium fluoride from the acid cooler to the storage tank, and the other conveying circuit conveys acidic potassium fluoride from the storage tank to the acid cooler; the conveying circuit includes a connecting pipe, a coolant circulation pump installed on the connecting pipe, and a regulating valve.

[0019] The emergency flow interruption mechanism includes a gas tank connected to the segmented cooling mechanism and a water tank connected between the gas tank and the segmented cooling mechanism.

[0020] The fluorine recovery mechanism includes an absorption assembly connected to a segmented cooling mechanism; the absorption assembly includes two-stage absorption towers.

[0021] The exhaust gas purification mechanism includes an alkaline scrubbing assembly, a wet electrostatic precipitator, and an induced draft fan connected to the fluorine recovery mechanism; the alkaline scrubbing assembly includes a two-stage alkaline scrubbing tower.

[0022] (III) Beneficial Effects

[0023] This invention employs a five-step process: pre-mixing, pyrolysis and fluorination, rapid cooling and absorption, spray absorption, and tail gas purification. It extracts high-purity potassium fluoride solutions (including both acidic and alkaline solutions), achieving environmentally compliant emissions after waste gas and liquid recovery. A high-temperature method is used in the pyrolysis chamber to decompose hydrofluoroethers and their high-boiling-point compounds, releasing fluorine and fluorinating the remaining potassium hydroxide. A segmented cooling mechanism is used for rapid cooling and spray absorption of most of the fluorides (potassium fluoride), obtaining an acidic potassium fluoride solution (containing potassium fluoride, hydrogen fluoride, and water). In the spray absorption stage, pure water absorbs fluorine in a high-efficiency packed absorption tower and is then transported to the segmented cooling mechanism to become the acidic potassium fluoride solution. In the tail gas purification stage, potassium hydroxide solution absorbs the remaining fluorine in an alkaline scrubbing tower, obtaining an alkaline potassium fluoride solution (containing potassium fluoride, potassium hydroxide, and water). The tail gas is finally further treated by a wet electrostatic precipitator before being discharged in compliance with standards. An emergency interruption mechanism is installed at the critical rapid cooling stage to prevent system accidents caused by power outages, pump shutdowns, or other abnormalities. This method has the advantages of high safety and reliability, high fluorine recovery efficiency, strong adaptability, and small footprint, and can effectively realize the resource utilization of waste. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the extraction system of the present invention;

[0025] Figure 2 For the present invention Figure 1 Enlarged view of region A in the middle;

[0026] Figure 3 For the present invention Figure 1 Enlarged view of region B in the middle;

[0027] Figure 4For the present invention Figure 1 Enlarged view of region C in the middle;

[0028] Figure 5 For the present invention Figure 1 Enlarged view of region D in the middle;

[0029] Figure 6 For the present invention Figure 1 Enlarged view of region E in the middle;

[0030] In the picture:

[0031] 1. Blending mechanism; 2. Spray pyrolysis mechanism; 3. Segmented cooling mechanism; 4. Emergency flow interruption mechanism; 5. Fluorine recovery mechanism; 6. Tail gas purification mechanism; 7. Storage tank; 8. Agitator; 9. Waste liquid inlet pipe; 10. Formula liquid inlet pipe; 11. Bottom-inserted compressed air pipe; 12. Pyrolysis chamber; 23. Fire control air pipeline; 24. Gas spray gun; 25. Liquid spray gun; 26. Large fire burner; 27. Perpetual flame gun; 28. Overflow weir; 39. Ring atomizer; 30. Storage tank; 31. Acid cooler; 32. Connecting pipe; 35. Coolant circulation pump; 35. Regulating valve; 35. Gas tank; 41. Water tank; 42. Absorption tower; 51. Wet electrostatic precipitator; 61. Exhaust fan; 62. Alkali washing tower; 63. Detailed Implementation

[0032] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] Please refer to Figure 1-6 As shown, a method for extracting high-purity potassium fluoride solution includes the following steps;

[0034] A1. Pre-mixing: The waste liquid is centrally stored in storage tank 11. Before pyrolysis, an appropriate amount of potassium hydroxide is added according to the composition of potassium fluoride and potassium hydroxide in the waste liquid, and the excess fluoride ratio is controlled to be 1.2 to 1.5. Then methanol is added to adjust the viscosity of the liquid. This facilitates spraying and prevents viscous clogging, avoiding nozzle blockage, corrosion, or scaling inside the pyrolyzer.

[0035] A2. Pyrolysis and Fluorination: First, auxiliary fuel is used to slowly raise the temperature. When the temperature reaches a certain level, the pyrolysis of the waste liquid begins. The waste liquid is transported to the pyrolyzer, and after oxygenation with air, it is quantitatively sprayed into the pyrolysis chamber 21 by liquid spray gun 24 located at the top of the pyrolyzer. The waste liquid changes from liquid to gas at high temperature, and then burns and decomposes. In actual implementation, the liquid spray gun 24 is reasonably arranged at an angle to ensure uniform distribution of the waste liquid and improve pyrolysis efficiency. To ensure sufficient residence time of the flue gas and scouring of the furnace body, the flow velocity of the flue gas inside the pyrolysis chamber 21 should be controlled within 4 m / s.

[0036] A3. Rapid cooling and absorption: The flue gas generated by pyrolysis enters the segmented cooling mechanism 3 through the overflow weir 31. A large amount of cooling water is sprayed out through the annular atomizer 32 to fully contact the flue gas, and the temperature drops instantly from 1200℃ to 70℃, preventing the regeneration of dioxins. While spraying and cooling, the water absorbs hydrogen fluoride and potassium fluoride in the flue gas to form an acidic potassium fluoride solution (containing potassium fluoride, hydrogen fluoride, and water). The acidic potassium fluoride solution is transported to the acid cooler 34 and then sprayed and cooled and absorbed again to reduce its solubility before being discharged into the storage tank 33.

[0037] A4. Interrupted Spray: A flow meter is installed on the acid outlet pipe of the acid cooler 34 and a shut-off valve is installed on the water outlet pipe of the water tank 42 for interlocking. When the flow meter does not detect the flow, the shut-off valve opens, and the water in the water tank 42 is sent to the segmented cooling mechanism 3 by high-pressure compressed air to protect the equipment.

[0038] A5. Spray absorption: The flue gas after rapid cooling absorption still contains acidic gases such as hydrogen fluoride. It enters the absorption tower 51 and uses spray water to absorb the hydrogen fluoride into hydrofluoric acid. After replenishing part of the solution in the absorption tower 51, it is transported to the storage tank 33.

[0039] A6. Exhaust gas purification: After being washed with water in absorption tower 51, the flue gas passes through alkaline washing tower 63. Potassium hydroxide solution is added to alkaline washing tower 63 to absorb a small amount of hydrogen fluoride in the flue gas, and after obtaining alkaline potassium fluoride solution, it is discharged into storage tank 33. After passing through alkaline washing tower 63, the flue gas is removed by wet electrostatic precipitator and then led to the chimney by induced draft fan 62 for discharge.

[0040] This invention employs a five-step process: pre-mixing, pyrolysis and fluorination, rapid cooling and absorption, spray absorption, and tail gas purification. It extracts high-purity potassium fluoride solution (including both acidic and alkaline solutions) to achieve environmentally compliant emissions after waste gas and liquid recovery. A high-temperature method is used in the pyrolysis chamber 21 to pyrolyze hydrofluoroethers and their high-boiling-point compounds to release fluorine and fluorinate the remaining potassium hydroxide. A segmented cooling mechanism 3 rapidly cools and sprays to absorb most of the fluorides (potassium fluoride), obtaining an acidic potassium fluoride solution (containing potassium fluoride, hydrogen fluoride, and water). During the spray absorption stage, pure water absorbs fluorine in a high-efficiency packed absorption tower 51 and is then transported to the segmented cooling mechanism 3 to become the acidic potassium fluoride solution. In the tail gas purification stage, potassium hydroxide solution absorbs the remaining fluorine in an alkaline scrubbing tower 63, obtaining an alkaline potassium fluoride solution (containing potassium fluoride, potassium hydroxide, and water). The tail gas is finally further treated by a wet electrostatic precipitator before being discharged in compliance with standards. An emergency interruption mechanism 4 is installed at the critical rapid cooling stage to prevent system accidents caused by power outages, pump shutdowns, or other abnormalities. This method has the advantages of high safety and reliability, high fluorine recovery efficiency, strong adaptability, and small footprint, and can effectively realize the resource utilization of waste.

[0041] An extraction system for extracting high-purity potassium fluoride solution is characterized by comprising a mixing mechanism 1, a spray pyrolysis mechanism 2, a segmented cooling mechanism 3, a flow interruption emergency mechanism 4, a fluoride recovery mechanism 5, and a tail gas purification mechanism 6.

[0042] Optionally, the mixing mechanism 1 includes a storage tank 11, a stirrer 12 disposed within the storage tank 11, a waste liquid inlet pipe 13 connected to the storage tank 11, a formula liquid inlet pipe 14, a bottom-mounted compressed air pipe 15, and a pressure gauge disposed on the bottom-mounted compressed air pipe 15. In actual implementation, waste liquid enters the storage tank 11 through the waste liquid inlet pipe 13, and the formula liquid enters the storage tank 11 through the formula liquid inlet pipe 14, wherein the formula liquid includes methanol and potassium hydroxide; compressed air enters the storage tank 11 through the bottom-mounted compressed air pipe 15 to regulate the air pressure inside the storage tank 11, facilitating the discharge of the pre-mixed liquid from the storage tank 11.

[0043] Optionally, the spray pyrolysis mechanism 2 includes a pyrolysis chamber 21, a combined pyrolyzer disposed above the pyrolysis chamber 21, and a fire control air box connected to the combined pyrolyzer; the fire control air box is connected to the combined pyrolyzer via a fire control air duct 22; the combined pyrolyzer includes a gas spray gun 23, a liquid spray gun 24, a large flame burner 25, and a permanent flame gun 26; the liquid spray gun 24 is connected to a storage tank 11. In actual implementation, waste gas is sprayed into the pyrolysis chamber 21 from the gas spray gun 23. After the large flame burner 25 and the permanent flame gun 26 are ignited, the flame extends downward in a spiral shape under the action of the fire control air box. The atomized waste liquid has an extremely small particle size and instantly vaporizes and decomposes upon encountering high temperatures.

[0044] Optionally, the segmented cooling mechanism 3 is connected below the pyrolysis chamber 21; the segmented cooling mechanism 3 includes an overflow weir 31 connected to the pyrolysis chamber 21, an annular atomizer 32 disposed below the overflow weir 31, a storage tank 33 located below the annular atomizer 32 and an acid cooler 34 connected to the annular atomizer 32; two or more layers of annular atomizers 32 are arranged between the overflow weir 31 and the storage tank 33; the annular atomizer 32 includes 12-16 spray guns, arranged in 3-4 layers.

[0045] Optionally, the segmented cooling mechanism 3 also includes a graphite inner wall between the annular atomizer 32 and the overflow weir 31 and a cooling circuit connecting the storage tank 33 and the acid cooler 34; the cooling circuit includes two parallel conveying circuits; one conveying circuit conveys acidic potassium fluoride from the acid cooler 34 to the storage tank 33, and the other conveying circuit conveys acidic potassium fluoride from the storage tank 33 to the acid cooler 34; the conveying circuit includes a connecting pipe 351, a coolant circulation pump 352 disposed on the connecting pipe 351, and a regulating valve 353.

[0046] In actual implementation, the segmented cooling mechanism 3 is used for the emergency cooling absorption step. In the rapid cooling absorption step, the coolant is divided into 3 paths. The first path descends through the overflow weir 31 and forms a water curtain at the inner wall of the graphite to isolate the high-temperature flue gas and prevent high temperature damage to the inner wall of the graphite.

[0047] The second path forms a downward spray through the upper ring atomizer 32, which is the core section for rapid cooling of the flue gas. A large amount of atomized water is sprayed in through the spray gun to instantly cool the high temperature of the flue gas.

[0048] The third path, through the lower-level annular atomizer 32, forms a downward spray to further cool the smoke until it meets the requirements of the downstream system, and then enters the storage tank 33 for storage.

[0049] To prevent coolant flow interruption and high-temperature flue gas damage to equipment due to cooling pump failure or power outage, thus avoiding safety and environmental accidents, the emergency flow interruption mechanism 4 optionally includes an air tank 41 connected to the segmented cooling mechanism 3 and a water tank 42 connected between the air tank 41 and the segmented cooling mechanism 3. In actual implementation, once the coolant flow is interrupted, the shut-off valve is immediately opened to send water into the segmented cooling mechanism 3 through high-pressure compressed air, maintaining a spraying time of 10-20 minutes to achieve a protective shutdown.

[0050] Optionally, the fluorine recovery unit 5 includes an absorption assembly connected to the segmented cooling unit 3; the absorption assembly includes a two-stage absorption tower 51. Specifically, the fluorine recovery unit 5 absorbs the fluorine element, which has been decomposed into a gaseous phase, to produce hydrofluoric acid.

[0051] Optionally, the exhaust gas purification mechanism 6 includes an alkaline scrubbing assembly connected to the fluorine recovery mechanism 5, a wet electrostatic precipitator 61, and an induced draft fan 62; the alkaline scrubbing assembly includes a two-stage alkaline scrubbing tower 63. The flue gas after fluorine recovery enters the two-stage alkaline scrubbing tower 63 to neutralize residual acidic substances in the flue gas, and then undergoes deep dust purification through a wet electrostatic precipitator. The flue gas is then led to the chimney by the induced draft fan 62.

[0052] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention's specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for extracting high-purity potassium fluoride solution, characterized in that, Includes the following steps; A1. Pre-mixing: The waste liquid is centrally stored in a storage tank. Before pyrolysis, an appropriate amount of potassium hydroxide is added according to the composition of potassium fluoride and potassium hydroxide in the waste liquid, and the excess fluoride ratio is controlled to be 1.2~1.

5. Then methanol is added to adjust the viscosity of the liquid. A2. Pyrolysis and Fluorination: The waste liquid is transported to the pyrolysis unit. After oxygenation by air, the waste liquid is metered into the pyrolysis chamber by a liquid spray gun located at the top of the pyrolysis unit. The waste liquid changes from liquid to gas at high temperature, and then burns and decomposes. A3. Rapid Cooling Absorption: The flue gas generated by pyrolysis enters the segmented cooling mechanism through the overflow weir. A large amount of cooling water is sprayed out through the annular atomizer to fully contact the flue gas, and the temperature drops instantly from 1200℃ to 70℃, preventing the regeneration of dioxins. While spraying and cooling, the water absorbs hydrogen fluoride and potassium fluoride in the flue gas to form an acidic potassium fluoride solution. The acidic potassium fluoride solution is transported to the acid cooler and then sprayed and cooled and absorbed again to reduce its solubility before being discharged into the storage tank. A4. Interrupted spray: A flow meter is installed on the acid outlet pipe of the acid cooler and a shut-off valve on the water outlet pipe of the water tank is interlocked. When the flow meter does not detect flow, the shut-off valve opens, and the water in the water tank is sent to the segmented cooling mechanism by high-pressure compressed air to protect the equipment. A5. Spray absorption: The flue gas after rapid cooling absorption still contains hydrogen fluoride. It enters the absorption tower and is absorbed by spray water to form hydrofluoric acid. After replenishing part of the solution in the absorption tower, it is transported to the storage tank. A6. Exhaust gas purification: After the flue gas is washed with water in the absorption tower, it passes through the alkaline washing tower. In the alkaline washing tower, potassium hydroxide solution is added to absorb the small amount of hydrogen fluoride in the flue gas, and the potassium fluoride solution is discharged into the storage tank. After passing through the alkaline washing tower, the flue gas is removed by a wet electrostatic precipitator and then led to the chimney by an induced draft fan for discharge.

2. The extraction system based on the method for extracting high-purity potassium fluoride solution according to claim 1, characterized in that: It includes a blending mechanism, a spray pyrolysis mechanism, a segmented cooling mechanism, an emergency flow interruption mechanism, a fluorine recovery mechanism, and an exhaust gas purification mechanism; The mixing mechanism includes a storage tank, a stirrer installed inside the storage tank, a waste liquid inlet pipe connected to the storage tank, a formula liquid inlet pipe, a bottom-inserted compressed air pipe, and a pressure gauge installed on the bottom-inserted compressed air pipe. The spray pyrolysis mechanism includes a pyrolysis chamber, a combined pyrolyzer disposed above the pyrolysis chamber, and a fire control air box connected to the combined pyrolyzer; the fire control air box is connected to the combined pyrolyzer via a fire control air duct; the combined pyrolyzer includes a gas spray gun, a liquid spray gun, a large-fire combustion gun, and a continuous-burning flame gun; the liquid spray gun is connected to a storage tank; The segmented cooling mechanism is connected to the bottom of the pyrolysis chamber; the segmented cooling mechanism includes an overflow weir connected to the pyrolysis chamber, an annular atomizer disposed below the overflow weir, a storage tank disposed below the annular atomizer, and an acid cooler connected to the annular atomizer; two or more layers of annular atomizers are arranged between the overflow weir and the storage tank; the annular atomizer includes 12-16 spray guns, arranged in 3-4 layers; The segmented cooling mechanism also includes a graphite inner wall between the annular atomizer and the overflow weir, and a cooling circuit connecting the storage tank and the acid cooler; the cooling circuit includes two parallel conveying circuits; one conveying circuit conveys acidic potassium fluoride from the acid cooler to the storage tank, and the other conveying circuit conveys acidic potassium fluoride from the storage tank to the acid cooler; each conveying circuit includes a connecting pipe, a coolant circulation pump installed on the connecting pipe, and a regulating valve; The emergency flow interruption mechanism includes a gas tank connected to the segmented cooling mechanism and a water tank connected between the gas tank and the segmented cooling mechanism.

3. The extraction system as described in claim 2, characterized in that: The fluorine recovery mechanism includes an absorption assembly connected to a segmented cooling mechanism; the absorption assembly includes a two-stage absorption tower.

4. The extraction system as described in claim 3, characterized in that: The exhaust gas purification mechanism includes an alkaline scrubbing assembly, a wet electrostatic precipitator, and an induced draft fan connected to the fluorine recovery mechanism; the alkaline scrubbing assembly includes a two-stage alkaline scrubbing tower.

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