Device and method for preparing high-purity hydrofluoric acid based on directional separation refining of fluorine-containing sludge

Abstract

The application provides a device and method for preparing high-purity hydrofluoric acid based on directional separation and refining of fluorine-containing sludge. The device for preparing high-purity hydrofluoric acid based on directional separation and refining of fluorine-containing sludge comprises a pre-reaction device, a reaction furnace, a washing device and a rectifying device connected in sequence; the first end face of the reaction furnace is provided with a first air inlet, a second air inlet and a feeding port communicating with the furnace cavity; the second air inlet surrounds the first air inlet; the feeding port corresponds to the second air inlet; the first end and the tail end of the reaction furnace are respectively provided with a first gas outlet and a second gas outlet; the second gas outlet is connected with the washing device; and a flow guide assembly is further arranged in the furnace cavity. The application can improve the fluorine resource recovery efficiency and the gas separation stability, make the obtained raw material gas more suitable for subsequent preparation of high-purity hydrofluoric acid, and realize the cooperation of impurity removal and purification filtration, so as to accurately control the product purity, impurities and particle size, and realize the economic and environmental protection of acid liquid recycling.

Description

Technical Field

[0001] This application relates to the field of sludge treatment technology in the semiconductor industry, and in particular to an apparatus and method for preparing high-purity hydrofluoric acid from fluoride-containing sludge based on directional separation and purification. Background Technology

[0002] In the broader semiconductor industry, processes such as integrated circuits, display panels, photovoltaics, and fluorochemicals all generate fluorinated sludge. This sludge has a complex composition, typically containing calcium fluoride, amorphous silica, calcium carbonate, calcium hydroxide, and soluble fluoride salts. If traditional landfill or stockpiling methods are used for disposal, fluoride ions will leach out with rainwater, polluting the soil and groundwater.

[0003] In related technologies, fluorine-containing sludge generated in the semiconductor industry is typically treated with acid leaching and precipitation to prepare regenerated fluorite powder. However, this method has limited adaptability to the complex components in fluorine-containing sludge. During the conversion process, different fluorine-containing gases and impurity gases easily mix and trigger side reactions. A large amount of amorphous silica in fluorine-containing sludge has a much higher reactivity than crystalline silica. It reacts rapidly with HF in the initial low-temperature section of the pre-reactor and reactor to generate silicon tetrafluoride (SiF4) gas. Traditional processes do not address this characteristic with targeted separation and resource recovery methods. The SiF4 and HF mixture is transported together throughout the process, easily reacting with water to form fluorosilicic acid, which is difficult to remove completely through conventional washing and distillation processes. This severely restricts the purity of the final hydrofluoric acid product and fails to meet the stringent requirements of the semiconductor industry for the impurity content of electronic-grade hydrofluoric acid. Furthermore, there are issues with incomplete impurity removal and low fluorine resource recovery rates. Summary of the Invention

[0004] Based on this, this application provides an apparatus and method for preparing high-purity hydrofluoric acid from fluoride-containing sludge using directional separation and purification, to solve the aforementioned technical problems. This reaction apparatus achieves directional separation of the mixed gas at the beginning and end of the furnace chamber, while preventing backflow of gas flow. This promotes stable reaction of the fluoride-containing sludge and inhibits disordered mixing of different gases, thereby improving the efficiency of fluorine resource recovery and utilization, enhancing impurity control and product purity, and improving the stability of the reaction process and the reliability of the apparatus operation.

[0005] In a first aspect, this application provides an apparatus for preparing high-purity hydrofluoric acid from fluoride-containing sludge based on directional separation and purification, comprising a pre-reaction device, a reactor, a washing device, and a distillation device connected in sequence; the reactor has a first air inlet, a second air inlet, and a feed inlet at its front end, which are connected to the furnace cavity, the second air inlet surrounding the first air inlet, and the feed inlet corresponding to the second air inlet; the reactor has a first gas outlet and a second gas outlet at its front and rear ends, respectively, the second gas outlet being connected to the washing device; and a flow guiding component is also provided inside the furnace cavity.

[0006] In some embodiments, a flow stabilizer is provided at the first air inlet, and the flow stabilizer is provided with a plurality of air holes evenly distributed thereon.

[0007] In some embodiments, the first air inlet has a circular cross-section, the second air inlet has an annular cross-section, the first air inlet and the second air inlet are coaxially arranged, and the cross-sectional area of ​​the first air inlet is smaller than that of the second air inlet.

[0008] In some embodiments, the system further includes a gas source assembly and a gas trapping device, wherein the gas source assembly is connected to the first air inlet and the second air inlet respectively, and the gas trapping device is connected to the first air outlet.

[0009] In some embodiments, the flow guiding assembly includes a first flow guiding plate, which is arranged in a ring within the furnace cavity and corresponds to the second air inlet. The first flow guiding plate is inclined along the tail end of the reactor in the direction toward the central region of the furnace cavity.

[0010] In some embodiments, the tilt angle of the first guide vane is in the range of 30°-45°.

[0011] In some embodiments, the flow guiding assembly includes a plurality of second flow guiding plates arranged in a ring shape. The plurality of second flow guiding plates are coaxially arranged and spaced apart along the direction toward the tail end of the reactor. The outer diameter and inner diameter of the plurality of second flow guiding plates gradually decrease along the direction toward the tail end of the reactor.

[0012] In some embodiments, the pre-reaction device includes a housing and a feeding mechanism. The housing has a cavity, a connecting port, and a vent. The connecting port and the vent are respectively connected to the cavity. The connecting port is connected to the feed inlet. The vent is connected to the washing device. The feeding mechanism is partially located within the cavity. The feeding mechanism is used to convey raw materials to the cavity and to convey materials within the cavity to the feed inlet.

[0013] In some embodiments, the washing device is used to remove impurities from the gas and purify it. The washing device includes a pre-washing tower, a main washing tower, and a distillation device. The inlet of the pre-washing tower is connected to the gas guide port and the second gas outlet. The outlet of the pre-washing tower is connected to the inlet of the main washing tower. The outlet of the pre-washing tower is connected to the distillation device.

[0014] In some embodiments, the acid outlet of the distillation apparatus is connected to the acid inlet of the pre-washing tower for supplying acid to the pre-washing tower;

[0015] The acid outlet of the distillation apparatus is also connected to the mixed acid inlet of the feeding mechanism in the pre-reaction apparatus for supplying acid to the pre-reaction apparatus.

[0016] In some embodiments, the washing apparatus further includes an acid distribution pump and an acid mixing tank connected in sequence, and the acid outlet of the main washing tower is connected to the acid inlet of the pre-washing tower through the acid distribution pump and the acid mixing tank.

[0017] In some embodiments, the washing apparatus further includes a circulating pump and a condenser connected in sequence, and the acid outlet of the main washing tower is connected to the acid inlet of the main washing tower through the circulating pump and the condenser.

[0018] In some embodiments, the washing apparatus further includes a demister, the gas outlet of the main washing tower is connected to the demister, the gas outlet of the demister is connected to the distillation unit, and the acid outlet of the demister is connected to the bottom of the main washing tower.

[0019] In some embodiments, the distillation apparatus is used to separate and purify gas. The distillation apparatus includes a first distillation column, a first condensation column, a second distillation column, a second condensation column, an absorption column, and a filter assembly. The feed inlet of the first distillation column is connected to the washing device. The first distillation column, the second distillation column, the second condensation column, the absorption column, and the filter assembly are connected in sequence. The top outlet of the first distillation column is also connected to the first condensation column.

[0020] In some embodiments, the outlet of the second condenser is connected to the bottom of the first distillation column; the outlet of the first condenser is connected to the bottom of the first distillation column.

[0021] Secondly, this application also provides a method for preparing high-purity hydrofluoric acid from fluorinated sludge, applied to the apparatus for preparing high-purity hydrofluoric acid from fluorinated sludge based on directional separation and purification described in the first aspect, comprising the following steps:

[0022] Fluorine-containing sludge powder and mixed acid are separately added into a pre-reaction device for mixing, and the fluorine-containing sludge powder and mixed acid undergo a single reaction in the pre-reaction device.

[0023] The mixture after the first reaction is conveyed into the reactor, and gas is introduced into the reactor to mix the mixture a second time and carry out a second reaction.

[0024] The hydrogen fluoride gas generated from the primary and secondary reactions is sent to a scrubbing device for washing and impurity removal.

[0025] The washed and purified hydrogen fluoride gas is sent to a distillation unit for distillation, filtration, and purification.

[0026] This application has at least the following beneficial effects:

[0027] The pre-reaction unit, reactor, washing unit, and distillation unit are sequentially connected. The washing unit is used to remove impurities and purify the gas, and the distillation unit is used to separate and purify the gas. The reactor has a first air inlet, a second air inlet, and a feed inlet at its head, all connected to the furnace cavity, with the second air inlet surrounding the first air inlet. A flow guiding assembly is also installed inside the furnace cavity. Negative pressure airflow is supplied to the first air inlet, and high-temperature airflow is supplied to the second air inlet. The first and second air inlets, together with the flow guiding assembly, form a directional flow field. The first air inlet introduces high negative pressure, high velocity central air, forming a central low-pressure reflux zone in the central area of ​​the furnace cavity. This forces the SiF4 gas generated at the head of the furnace cavity to converge at the first air outlet and exit from there. The second air inlet supplies hot air into the furnace cavity, carrying a mixture of fluorinated sludge powder and acid supplied from the feed inlet towards the tail end of the furnace cavity. The flow guiding component is used to prevent gas from flowing back from the tail end of the furnace cavity to the head end, while simultaneously separating the airflow between the low-temperature zone at the head end and the high-temperature zone at the tail end, ensuring directional airflow and creating a stable high-temperature zone in the middle and tail sections of the furnace cavity. This promotes the full fluorination reaction and HF generation. The flow guiding component also gathers the gas at the tail end of the furnace cavity and directs it to the second outlet, creating a slight negative pressure at the tail end, thus enabling the directional extraction of HF. This overall configuration creates a pressure gradient along the furnace's longitudinal axis and a radial pressure gradient, achieving a dual-effect flow field of central extraction and peripheral propulsion. The arrangement of the first and second air inlets, along with the flow guiding component, constitutes a pressure field control system distributed along the furnace's longitudinal axis, forming a stable pressure gradient of "high negative pressure at the head end of the furnace cavity → low negative pressure in the middle section of the furnace cavity → slight negative pressure at the tail end of the furnace cavity." This achieves directional separation of the mixed gas at the head and tail ends of the furnace cavity while preventing backflow. This promotes the stable reaction of fluorine-containing sludge and inhibits the disorderly mixing of different gases, thereby improving the efficiency of fluorine resource recovery and utilization, improving the effect of impurity control and product preparation purity, and enhancing the stability of the reaction process and the reliability of equipment operation.

[0028] Meanwhile, the tandem system of pre-washing and main washing, coupled with the purification process of multi-stage distillation, precisely controls product purity, impurities, and particle size, while acid reuse balances economic efficiency and environmental friendliness. Attached Figure Description

[0029] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0030] Figure 1 This is a schematic diagram of the reactor structure in one embodiment of this application;

[0031] Figure 2 This is a schematic diagram of the reactor and pre-reaction device in one embodiment of this application;

[0032] Figure 3 This is a schematic diagram of a device for preparing high-purity hydrofluoric acid from fluoride-containing sludge based on directional separation and purification, according to one embodiment of this application.

[0033] Explanation of reference numerals in the attached figures:

[0034] 100 - A device for preparing high-purity hydrofluoric acid from fluoride-containing sludge based on directional separation and purification;

[0035] 10-Pre-reaction device; 11-Shell; 12-Feeding mechanism; 121-First feeding mechanism; 122-Second feeding mechanism;

[0036] 20 - Reactor; 21 - Furnace cavity; 22 - First air inlet; 23 - Second air inlet; 24 - First gas outlet; 25 - Second gas outlet;

[0037] 30 - Gas source assembly;

[0038] 40 - Flow guide assembly; 41 - First flow guide plate; 42 - Second flow guide plate;

[0039] 50-Washing device; 51-Pre-washing tower; 52-Main washing tower; 53-Distillation device; 54-Circulating pump; 55-Condenser; 56-Demister; 57-Acid separator pump; 58-Mixed acid tank;

[0040] 60 - Distillation apparatus; 61 - First distillation column; 62 - First condenser column; 63 - Second distillation column; 64 - Second condenser column; 65 - Absorption column; 66 - Filter assembly.

[0041] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar components or components having the same or similar functions throughout. The described embodiments are some, but not all, of the embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0043] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an indirect connection through an intermediate medium, or the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0044] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0045] The terms “first,” “second,” and “third” (if any) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0046] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such that a process, method, system, product, or display that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or display.

[0047] In the broader semiconductor industry, processes such as integrated circuits, display panels, photovoltaics, and fluorochemicals all generate fluorinated sludge. This sludge has a complex composition, typically containing calcium fluoride, amorphous silica, calcium carbonate, calcium hydroxide, and soluble fluoride salts. If traditional landfill or stockpiling methods are used for disposal, fluoride ions will leach out with rainwater, polluting the soil and groundwater.

[0048] In related technologies, fluorine-containing sludge generated in the semiconductor industry is typically treated with acid leaching and precipitation to prepare regenerated fluorite powder. However, this method has limited adaptability to the complex components in fluorine-containing sludge. During the conversion process, different fluorine-containing gases and impurity gases easily mix and trigger side reactions. A large amount of amorphous silica in fluorine-containing sludge has a much higher reactivity than crystalline silica. It reacts rapidly with HF in the initial low-temperature section of the pre-reactor and reactor to generate silicon tetrafluoride (SiF4) gas. Traditional processes do not address this characteristic with targeted separation and resource recovery methods. The SiF4 and HF mixture is transported together throughout the process, easily reacting with water to form fluorosilicic acid, which is difficult to remove completely through conventional washing and distillation processes. This severely restricts the purity of the final hydrofluoric acid product and fails to meet the stringent requirements of the semiconductor industry for the impurity content of electronic-grade hydrofluoric acid. Furthermore, there are issues with incomplete impurity removal and low fluorine resource recovery rates.

[0049] In view of this, how to achieve orderly gas separation, directional extraction, and stable discharge in the process of preparing hydrofluoric acid from fluorinated sludge has become an urgent technical problem to be solved. To address this problem, a device and method for preparing high-purity hydrofluoric acid from fluorinated sludge based on directional separation and purification is proposed. The arrangement of the first and second air inlets, along with the flow guiding components, constitutes a pressure field control system distributed along the longitudinal axis of the reactor. This creates a stable pressure gradient of "high negative pressure at the beginning of the furnace chamber → low negative pressure in the middle section of the furnace chamber → slight negative pressure at the end of the furnace chamber," achieving directional separation of the mixed gas at the beginning and end of the furnace chamber while preventing backflow. This promotes stable reaction of the fluorinated sludge and inhibits disordered mixing of different gases, thereby improving the efficiency of fluorine resource recovery and utilization, improving impurity control and product purity, and enhancing the stability of the reaction process and the reliability of the device operation.

[0050] The following describes in detail, with reference to the accompanying drawings, the apparatus and method for preparing high-purity hydrofluoric acid from fluoride-containing sludge based on directional separation and purification, as provided in the embodiments of this application.

[0051] like Figure 1 , Figure 2 and Figure 3 As shown, this application provides a device 100 for preparing high-purity hydrofluoric acid from fluoride-containing sludge based on directional separation and purification. The device 100 for preparing high-purity hydrofluoric acid from fluoride-containing sludge based on directional separation and purification includes a pre-reaction device 10, a reaction furnace 20, a washing device 50 and a distillation device 60 connected in sequence.

[0052] The reactor 20 has a first air inlet 22, a second air inlet 23 and a feed inlet on the front end face, which are connected to the furnace cavity 21. The second air inlet 23 surrounds the first air inlet 22 and the feed inlet corresponds to the second air inlet 23. The reactor 20 has a first gas outlet 24 and a second gas outlet 25 at the front and rear ends, respectively. The second gas outlet 25 is connected to the washing device 50. The furnace cavity 21 is also equipped with a flow guiding component 40.

[0053] The apparatus 100 for preparing high-purity hydrofluoric acid from fluorinated sludge based on directional separation and purification provided in this application embodiment comprises a pre-reaction device 10, a reactor 20, a washing device 50, and a distillation device 60 connected in sequence. The washing device 50 is used to remove impurities and purify the gas, and the distillation device 60 is used to separate and purify the gas. A first air inlet 22 is used to introduce high negative pressure and high flow rate central air, forming a central low-pressure reflux zone in the central region of the furnace cavity 21, forcing the SiF4 gas generated at the beginning of the furnace cavity 21 to converge to the first air outlet 24 and be discharged from the first air outlet 24. A second air inlet 23 delivers hot air at 350-450°C into the furnace cavity 21, carrying the mixture of fluorinated sludge powder and acid delivered from the feed inlet to the furnace cavity 21 towards the end of the furnace cavity 21. The flow guiding component 40 is used to prevent the gas from flowing back from the tail end of the furnace cavity 21 to the head end, and at the same time separates the airflow in the low-temperature zone (100-150℃) at the head end of the furnace cavity 21 from the high-temperature zone (250-400℃) at the tail end of the furnace cavity 21, ensuring directional airflow and forming a stable high-temperature zone in the middle and tail ends of the furnace cavity 21, promoting the full fluorination reaction and HF generation. The flow guiding component 40 is also used to gather the gas at the tail end of the furnace cavity 21 and guide it to the second gas outlet 25, so that a slight negative pressure of -2~-3 kPa is formed at the tail end of the furnace cavity 21, and the gas flow velocity in the second gas outlet 25 is maintained at 15~25 m / s, thereby enabling the directional extraction of HF and its delivery to the scrubbing device 50. This overall configuration can form a pressure gradient along the furnace length axis and a radial pressure gradient (high negative pressure at the center > lower negative pressure in the annular main air duct), achieving a dual-effect flow field of central extraction and peripheral propulsion. The arrangement of the first and second air inlets, along with the flow guiding assembly 40, forms a pressure field control system distributed along the longitudinal axis of the reactor 20. This creates a stable pressure gradient: high negative pressure at the beginning of the furnace chamber 21 → low negative pressure in the middle section of the furnace chamber 21 → slight negative pressure at the end of the furnace chamber 21. This achieves directional separation of the mixed gas at the beginning and end of the furnace chamber 21, while preventing backflow. This promotes stable reaction of fluorine-containing sludge and inhibits disordered mixing of different gases, thereby improving the efficiency of fluorine resource recovery, enhancing impurity control and product purity, and increasing the stability of the reaction process and the reliability of the equipment operation. This setup, on the one hand, reduces cross-mixing of different components within the furnace, decreasing the probability of entrainment of impurities such as silicon tetrafluoride and dust in subsequent stages. On the other hand, it reduces the disturbance of the pressure field within the furnace caused by gas retention and backflow, thereby improving fluorine resource recovery efficiency and gas separation stability, making the resulting raw material gas more suitable for subsequent preparation of high-purity hydrofluoric acid.

[0054] The reactor 20 serves as the main shell for the thermal reaction of fluorinated sludge. A furnace cavity 21 is formed within the reactor 20, and a first air inlet 22, a second air inlet 23, and a feed inlet are provided on the first end face, connecting the furnace cavity 21. The second air inlet 23 is arranged around the first air inlet 22, and the feed inlet and the second air inlet 23 are arranged circumferentially corresponding to each other. A first gas outlet 24 and a second gas outlet 25, connecting the furnace cavity 21, are respectively provided at the first and last ends of the reactor 20, allowing gases generated in different areas within the furnace cavity 21 to be discharged in different directions. The reactor 20 can be a horizontal cylindrical furnace body. The furnace shell can be made of high-temperature alloy steel lined with fluorinated ceramic, graphite composite lining, or stainless steel lined with fluorinated material. The inner surface of the furnace cavity 21 can be a smooth cylindrical surface, a gradually expanding conical surface, or a locally guiding curved surface. The length-to-diameter ratio of the furnace cavity 21 can be set from 1.5:1 to 10:1. The first air inlet 22 and the second air inlet 23 are arranged in a ring at intervals to facilitate the formation of a differentiated airflow organization of negative pressure intake and high temperature air supply. The spacing between the openings at the beginning meets the requirements of flange sealing, pipeline assembly and thermal expansion compensation.

[0055] The flow guiding assembly 40 is disposed within the furnace cavity 21 to guide and divert the high-temperature airflow entering the furnace cavity 21. This alters the streamline distribution of the airflow within the furnace cavity 21 and creates a predetermined pressure zone in the front or middle section near the second air inlet 23. The flow guiding assembly 40 can be made of a metal plate, ceramic plate, graphite plate, or composite fluorine-resistant material. Its shape can be an annular plate, inclined plate, conical guide plate, arc guide plate, or a multi-stage annular guide plate structure. Its outer diameter is adapted to the inner diameter of the furnace cavity 21. The plate thickness can be set from several millimeters to tens of millimeters depending on the heat load and mechanical strength. The guiding angle, spacing, and coverage length are matched to the length of the furnace cavity 21 and the airflow velocity to ensure stable directional flow under high-temperature conditions.

[0056] The discharge end of the pre-reaction device 10 is connected to the feed inlet of the reactor 20. The pre-reaction device 10 is used to pretreat fluorine-containing sludge and transfer the material to the reactor 20. The pre-reaction device 10 is also used to homogenize, dewater, crush, screen, preheat, or premix the fluorine-containing sludge to reduce the impact of raw material fluctuations on subsequent reactions.

[0057] The reactor 20 is used to convert pretreated fluorine-containing components into fluorine-containing gas under heating or reaction atmosphere conditions.

[0058] The discharge end of the scrubbing unit 50 is connected to the feed end of the distillation unit 60. The scrubbing unit 50 is used for staged impurity removal and gas-liquid contact purification of the reaction gas. The scrubbing unit 50 typically removes dust, acid mist, soluble impurities, and some by-product gases from the reaction gas through spraying, packed contact, or bubbling scrubbing. The scrubbing unit 50 can further purify the crude gas, reducing the impact of fluoride compounds, suspended particles, and corrosive entrainments on subsequent distillation stages, and providing a relatively stable intermediate product for obtaining high-purity hydrofluoric acid.

[0059] The feed end of the distillation unit 60 is connected to the purified discharge end of the washing unit 50. The distillation unit 60 is used to further separate and purify the washed gas or absorbent, separating hydrofluoric acid from water, low-boiling impurities, and residual acidic components, thereby obtaining the target product that meets the process requirements. The distillation unit 60 can refine the product obtained after washing, increasing the concentration and purity of hydrofluoric acid, and reducing the content of metal ions, silicon and fluorine impurities, and water.

[0060] By sequentially connecting the pre-reaction unit 10, reactor 20, washing unit 50, and distillation unit 60 according to the process flow, a continuous linkage path is formed from raw material conditioning, conversion of fluorine-containing components, gas purification to product refining. During operation, fluorine-containing sludge first enters the pre-reaction unit 10, where it is homogenized, dehydrated, and pretreated before being stably conveyed to the reactor 20. Under heating and airflow organization, the reactor 20 converts the fluorine-containing components into fluorine-containing gas, and the resulting crude gas then enters the washing unit 50. Dust, acid mist, and soluble impurities are removed under liquid-gas contact conditions, and the gas further enters the distillation unit 60 for purification and separation, ultimately yielding high-purity hydrofluoric acid. Simultaneously, some washing liquid, condensate, or recovered acid can be returned to the system for recycling according to process requirements, thereby reducing raw material consumption and improving resource utilization. Because the units are connected in series in sequence and with sealed pipelines and corrosion-resistant components, they can maintain continuous and stable operation in fluorine-containing and highly corrosive media environments. This allows gaseous impurities to be removed step by step, reducing the generation of fluorosilicic acid, acid mist entrainment and product fluctuations, improving the recovery rate of fluorine resources and the purity and process stability of the final hydrofluoric acid product.

[0061] In some embodiments, a flow stabilizer is provided at the first air inlet 22, and the flow stabilizer is evenly distributed with multiple air holes.

[0062] Specifically, the flow stabilizer is installed at the outlet end of the first air inlet 22. The flow stabilizer is a plate-shaped component used to evenly distribute and rectify the negative pressure airflow entering the furnace cavity 21. Its function is to ensure that the airflow entering from the first air inlet 22 undergoes diversion and velocity equalization before entering the furnace cavity 21, thereby reducing airflow pulsation, reducing local jet impact, and improving the flow field stability in the furnace head area.

[0063] Understandably, the flow stabilizer can be installed using methods such as flange clamping, screw fixing, welding connection, or snap-fit ​​limiting, so that the flow stabilizer is reliably fixed on the air inlet frame and avoids loosening or displacement under the action of high temperature airflow and negative pressure fluctuations.

[0064] The shape of the flow stabilizing plate can be configured as a disc, ring, boss, or multi-layer stacked structure, depending on the equipment structure and airflow organization requirements. Its material can be stainless steel, fluorine-resistant alloy, ceramic porous plate, or graphite composite plate, to balance high temperature resistance, corrosion resistance, and structural strength requirements. The vents can be round, elongated, conical, or honeycomb-shaped. The flow stabilizing plate effectively improves the uniformity of air intake at the first air inlet 22, enhances the controllability of negative pressure airflow, and makes the airflow organization within the furnace cavity 21 more stable. This helps reduce the mixing disturbance of different gas components during the conversion of fluorinated sludge, improves gas separation and extraction efficiency, and provides favorable conditions for impurity control and operational stability in the subsequent hydrofluoric acid preparation process.

[0065] In some embodiments, the first air inlet 22 has a circular cross-section, the second air inlet 23 has an annular cross-section, the first air inlet 22 and the second air inlet 23 are coaxially arranged, and the cross-sectional area of ​​the first air inlet 22 is smaller than the cross-sectional area of ​​the second air inlet 23.

[0066] The first air inlet 22 is a circular air inlet channel located at the center of the head end of the reactor 20, used to introduce negative pressure airflow into the furnace cavity 21. The second air inlet 23 is an annular air inlet channel arranged circumferentially around the first air inlet 22, used to deliver high-temperature airflow into the furnace cavity 21. The two are coaxially arranged, forming a composite air inlet structure with the central channel and the outer channel on the same axis. The circular cross-section of the first air inlet 22 is conducive to forming a more concentrated airflow stream. The annular cross-section of the second air inlet 23 facilitates uniform air distribution along the circumference. The coaxial arrangement of the two reduces the probability of flow deviation and vortex formation, thereby improving the uniformity of the temperature and pressure fields inside the furnace. The cross-sectional area of ​​the first air inlet 22 is smaller than that of the second air inlet 23, allowing the central channel to have a higher flow velocity and stronger negative pressure suction capacity under the same air supply conditions, while the annular channel, due to its larger cross-sectional area, can deliver more high-temperature gas in a relatively stable manner to meet the heat requirements of sludge dewatering, decomposition and release, and fluorine-containing component conversion.

[0067] The first air inlet 22 can be made into a short tube shape, a flared shape, or a converging nozzle shape to increase the airflow velocity with a smaller cross-section. The second air inlet 23 can be made into an annular groove, an annular slot, an annular nozzle, or an annular air cavity opening to uniformly deliver high-temperature airflow around the central opening. Its material can be corrosion-resistant metal, fluoropolymer-lined metal, ceramic sleeve, or high-temperature alloy to adapt to fluorine-containing media and high-temperature environments.

[0068] In some embodiments, the system further includes a gas source assembly 30 and a gas collection device. The gas source assembly 30 is connected to the first air inlet 22 and the second air inlet 23, respectively, and the gas collection device is connected to the first air outlet 24. The gas collection device is used to collect the SiF4 gas generated at the beginning of the furnace chamber 21.

[0069] The gas source assembly 30 is connected to the first air inlet 22 and the second air inlet 23 respectively, and is used to deliver negative pressure airflow to the first air inlet 22 and high temperature airflow to the second air inlet 23. This establishes a differential pressure field in the axial and radial directions within the furnace cavity 21 and provides a temperature gradient and flow direction control for the sludge reaction. The gas source assembly 30 may include one or more of the following: a negative pressure fan, an induced draft fan, a Roots blower, a high temperature hot air fan, a blower, a heater, and a regulating valve assembly. The gas supply pipeline may be made of stainless steel, fluoroplastic-lined pipe, or high-temperature alloy pipe.

[0070] In some embodiments, the flow guiding assembly 40 includes a first flow guiding plate 41, which is arranged in a ring within the furnace cavity 21 and corresponds to the second air inlet 23. The first flow guiding plate 41 is inclined along the tail end of the reactor 20 in the direction toward the central region of the furnace cavity 21.

[0071] The first guide plate 41 is located in the furnace cavity 21 region corresponding to the second air inlet 23, and can be arranged near the inner wall of the furnace cavity 21, at the transition of the furnace cavity 21 cross section, or at a location where the reaction gas flow is prone to diffusion. The annular structure is usually symmetrically arranged around the central axis of the furnace cavity 21 to adapt to the circumferential flow field distribution inside the furnace cavity 21. The first guide plate 41 is inclined towards the middle region of the furnace cavity 21 along the tail end of the reactor 20.

[0072] The first guide plate 41 is used to block the backflow of gas from the tail end of the furnace cavity 21 back to the head end, and at the same time separates the airflow from the low temperature zone of 100-150°C at the head end of the furnace cavity 21 to the high temperature zone of 250-400°C at the tail end of the furnace cavity 21, ensuring the directional flow of airflow, so that a stable high temperature zone is formed in the middle and tail ends of the furnace cavity 21, promoting the full progress of the fluorination reaction and the generation of HF.

[0073] The first guide plate 41 can be a single-layer ring plate, a folded-edge ring plate, a ring plate with reinforcing ribs, an arc-shaped ring plate, or a segmented spliced ​​ring plate to adapt to different furnace cavity 21 diameters, temperature conditions, and maintenance needs. Its material can be selected from high-temperature resistant stainless steel, fluorine-resistant alloy, graphite plate, alumina ceramic plate, or silicon carbide ceramic plate to meet the requirements of high temperature, corrosive atmosphere, and long-term operation.

[0074] Furthermore, multiple first guide plates 41 are provided, and the multiple first guide plates 41 are arranged at intervals along the axis of the furnace cavity 21.

[0075] In some embodiments, the tilt angle of the first guide vane 41 is in the range of 30°-45°.

[0076] The first guide plate 41 is typically positioned in the corresponding area of ​​the furnace cavity 21 near the second air inlet 23, and is installed at an angle along the tail end of the reactor 20. Its surface forms an angle of 30° to 45° with respect to the axial or radial reference plane of the furnace cavity 21, so as to provide sufficient guiding force while avoiding excessive obstruction of the airflow, which would result in significant swirling and turbulence.

[0077] In some embodiments, the flow guiding assembly 40 includes a plurality of second flow guiding plates 42, which are arranged in a ring shape. The plurality of second flow guiding plates 42 are coaxially arranged and spaced apart along the direction toward the tail end of the reactor 20. The outer diameter and inner diameter of the plurality of second flow guiding plates 42 gradually decrease along the direction toward the tail end of the reactor 20.

[0078] Specifically, the second guide plate 42 is an annular guide component disposed inside the furnace cavity 21. Its function is to guide and converge the high-temperature gas flow entering the furnace cavity 21 from the second air inlet 23 and the fluorine-containing gas generated during the reaction process in stages, so that the gas forms a stable axial flow field when transported along the tail of the furnace. Multiple second guide plates 42 are arranged coaxially along the axis of the reactor 20 and are arranged sequentially in the furnace cavity 21 at intervals. The annular flow channels formed between adjacent ring plates perform staged rectification of the gas flow, so that the gas gradually changes its velocity and direction as it passes through each stage of the guide space. Since the outer diameter and inner diameter of the multiple second guide plates 42 gradually decrease along the direction towards the tail of the reactor 20, a gradually decreasing diameter structure is formed between the previous stage guide plate and the next stage guide plate. Therefore, the gas flow will generate a gradually increasing contraction effect and pressure gradient when passing through, which is conducive to converging the relatively dispersed gas in the furnace to the central area and transporting it in an orderly manner towards the second gas outlet 25.

[0079] The second outlet 25 is connected to the washing device 50, which creates a slight negative pressure of -2kPa to -3kPa at the tail end of the furnace cavity 21, maintaining the gas flow velocity in the second outlet 25 at 15m / s to 25m / s, thereby enabling the directional extraction of HF.

[0080] The second guide plate 42 is generally installed on the inner wall of the furnace or the central support structure inside the furnace cavity 21 by means of a support ring, support rod or welded fastener, in order to maintain its coaxiality and high temperature resistance stability.

[0081] In some embodiments, the pre-reaction device 10 includes a housing 11 and a feeding mechanism 12. The housing 11 has a cavity, a connecting port, and an air inlet. The connecting port and the air inlet are respectively connected to the cavity. The connecting port is connected to the feed inlet. The air inlet is located at the top of the housing 11 and is connected to the washing device 50. The feeding mechanism 12 is partially located in the cavity. The feeding mechanism 12 is used to convey raw materials to the cavity and to convey materials in the cavity to the feed inlet.

[0082] The housing 11 forms a cavity for containing raw materials and intermediate materials. The housing 11 is provided with a connecting port and an air inlet. The connecting port communicates with the cavity and is connected to the feed inlet. The air inlet communicates with the cavity, is located at the top of the housing 11, and is connected to the washing device 50. The feeding mechanism 12 is partially located within the cavity and is used to transport raw materials into the cavity and to transport materials within the cavity to the feed inlet.

[0083] Furthermore, the feeding mechanism 12 includes a first feeding mechanism 121 and a second feeding mechanism 122. The first feeding mechanism 121 is located at the end of the cavity. The upper side of the first feeding mechanism 121 is provided with a material inlet and a mixed acid inlet. The second feeding mechanism 122 is located below the first feeding mechanism 121. The first feeding mechanism 121 and the second feeding mechanism 122 are arranged sequentially along the material conveying direction. The output end of the second feeding mechanism 122 is provided with a corresponding connection port.

[0084] The first feeding mechanism 121 is used to transport fluorinated sludge powder and mixed acid into the cavity for preliminary reaction. The second feeding mechanism 122 is used to transport the mixed materials from the cavity to the connecting port, and then through the connecting port into the furnace cavity 21.

[0085] Furthermore, both the first feeding mechanism 121 and the second feeding mechanism 122 are screw conveyors.

[0086] In some embodiments, the pre-reaction device 10 further includes a ball mill, a purification reactor, a mixing tank, a dewatering device, a dryer, a screening machine, and a grinding mill connected in sequence, with the discharge end of the grinding mill connected to the feeding mechanism 12.

[0087] In practical application, fluorinated sludge from various sources in the semiconductor industry is finely dispersed using a ball mill, then fed into a purification reactor where hydrofluoric acid solution (5%-6%) is added to remove impurities such as SiO2, CaCO3, and Ca(OH)2. The reacted material is then mixed evenly in a mixing tank and dehydrated to a moisture content ≤60% to form a sludge cake. The sludge cake is then conveyed to a dryer to obtain dry sludge powder, which is then conveyed to a screening machine to remove mechanical impurities. The dry sludge powder, after mechanical impurity removal, is then conveyed to a grinding mill and ground to the target particle size to obtain fluorinated sludge powder. Finally, the fluorinated sludge powder and mixed acid (a mixture of 98% concentrated sulfuric acid, 105% fuming sulfuric acid, and washing acid) are conveyed to a feeding mechanism 12, which then feeds the mixture into the reaction chamber for further reaction.

[0088] Furthermore, the dewatering equipment is either a plate and frame filter press or a centrifuge.

[0089] In some embodiments, the washing device 50 is used to remove impurities and purify the gas. The washing device 50 includes a pre-washing tower 51, a main washing tower 52 and a distillation device 53. The inlet of the pre-washing tower 51 is connected to the gas guide port and the second gas outlet 25. The outlet of the pre-washing tower 51 is connected to the inlet of the main washing tower 52. The outlet of the pre-washing tower 51 is connected to the distillation device 53.

[0090] In some embodiments, the acid outlet of the distillation apparatus 53 is connected to the acid inlet of the pre-washing tower 51 for supplying acid to the pre-washing tower 51; the acid outlet of the distillation apparatus 53 is also connected to the mixed acid inlet of the feeding mechanism 12 in the pre-reaction apparatus 10 for supplying acid to the pre-reaction apparatus 10.

[0091] In some embodiments, the washing device 50 further includes an acid distribution pump 57 and an acid mixing tank 58 connected in sequence, and the acid outlet of the main washing tower 52 is connected to the acid inlet of the pre-washing tower 51 through the acid distribution pump 57 and the acid mixing tank 58.

[0092] In some embodiments, the washing apparatus 50 further includes a circulation pump 54 and a condenser 55 connected in sequence, and the acid outlet of the main washing tower 52 is connected to the acid inlet of the main washing tower 52 through the circulation pump 54 and the condenser 55.

[0093] In some embodiments, the washing apparatus 50 further includes a demister 56, the gas outlet of the main washing tower 52 is connected to the demister 56, the gas outlet of the demister 56 is connected to the distillation apparatus 60, and the acid outlet of the demister 56 is connected to the bottom of the main washing tower 52.

[0094] The pre-washing tower 51 is a gas-liquid contact tower located at the front end of the washing device 50, used for primary cooling, dust removal, and coarse impurity removal of the fluorine-containing high-temperature gas from the reaction unit. The main washing tower 52 is a deep washing tower for further removal of acid mist, moisture, and fine particles. The distillation unit 53 is a regeneration unit used for heating and separating the washing liquid and recovering acid components. The inlet of the pre-washing tower 51 is connected to the gas guide port, allowing the fluorine-containing gas in the chamber to enter the pre-washing tower 51. The outlet of the pre-washing tower 51 is connected to the inlet of the main washing tower 52, so that the pre-treated gas can continue to enter the main washing tower 52 for subsequent purification. The outlet of the pre-washing tower 51 is connected to the distillation unit 53, allowing the enriched washing liquid collected at the bottom or side of the tower to be sent to the distillation unit 53 for regeneration. The outlet of the distillation unit 53 is connected to the pre-washing tower 51 and the feeding mechanism 12, respectively, so that part of the recovered liquid obtained by distillation is returned to the pre-washing tower 51 to form a circulating spray, and the other part is sent to the feeding mechanism 12 for replenishment or use in subsequent processes. The acid outlet of the main washing tower 52 is connected to the top of the main washing tower 52 and the pre-washing tower 51, respectively, thus forming an acid circulation loop that combines top reflux and front-end spray replenishment.

[0095] Specifically, the pre-washing tower 51 has an air inlet, an air outlet, an acid inlet, and a discharge outlet. The air inlet is located at the lower end of the pre-washing tower 51, the acid inlet is located at the top of the pre-washing tower 51, and the discharge outlet is connected to a storage tank located at the lower end of the pre-washing tower 51. The distillation unit 53 has a feed inlet, an acid outlet, and a discharge outlet. The main washing tower 52 has an air inlet, an acid outlet, an air outlet, and an acid inlet. The air inlet is located at the lower end of the main washing tower 52, the acid outlet is connected to an acid storage tank at the bottom of the main washing tower 52, and the air outlet is located at the upper end of the main washing tower 52. The air inlet of the pre-washing tower 51 is connected to a guide air inlet. The air outlet of the pre-washing tower 51 is connected to the air inlet of the main washing tower 52. The discharge outlet of the pre-washing tower 51 is connected to the feed inlet of the distillation unit 53. The acid outlet of the distillation unit 53 is connected to both the acid inlet and the mixed acid inlet of the pre-washing tower 51. The outlet of distillation unit 53 is connected to the impurity removal reactor. The acid outlet of the main washing tower 52 is connected to the acid inlet of the pre-washing tower 51 via acid distribution pump 57 and mixing tank 58. The acid outlet of the main washing tower 52 is also connected to the acid inlet of the main washing tower 52 via circulation pump 54 and condenser 55. The gas outlet of the main washing tower 52 is connected to distillation unit 60.

[0096] The crude HF gas (temperature 180~250℃) generated after the material in the chamber comes into contact with the mixed acid enters the inlet at the lower end of the pre-washing tower 51 through the gas inlet, with a gas inlet velocity of 8~12 m / s. The pre-washing tower 51 uses circulating mixed acid from the acid storage tank at the bottom of the main washing tower 52, which is transported to the mixed acid tank 58 by the acid distribution pump 57. The acid distribution pump 57 rotates at 1500~60 r / min, with a delivery flow rate of 5~8 m³ / h. In the mixed acid tank 58, it is mixed with added 105% fuming sulfuric acid to control the H₂SO₄ mass fraction in the spray medium after mixing to 70%~85%. As the spray medium, the spray flow rate is 10~15 m³ / h, achieving countercurrent gas-liquid contact. The inlet quench section of the pre-washing tower 51 is controlled at 80~90℃, with a spray pressure of 0.2~0.3MPa, rapidly cooling the high-temperature gas. Through gravity settling and spray collection, 90%~95% of solid dust (CaSO3, SiO2, H2SO4 acid mist) and some high-boiling substances are removed from the crude HF gas. The outlet section of the pre-washing tower 51 is controlled at 60~70℃, with an internal pressure of -1~-2kPa, reducing HF condensation losses, ensuring feed stability to the main washing tower 52, creating deep impurity removal conditions for the main washing tower 52, reducing blockage of the main washing tower 52, reducing the amount of impurities carried into the distillation system, and avoiding damage to the equipment from high-temperature gas, thus extending the equipment's service life.

[0097] After pre-washing, acid, HF, dust, and water are deposited in the storage tank at the bottom of pre-washing tower 51, where the temperature is 50-60℃. The material from the storage tank enters the distillation unit 53 through the outlet of pre-washing tower 51 for distillation at a temperature of 100-110℃ and a pressure of 0.1-0.12 MPa. A portion of the resulting acid is recycled back to pre-washing tower 51 for spraying at a flow rate of 4-6 m³ / h. The remaining portion is mixed with exogenous sulfuric acid at a ratio of 5:1-6:1 and recycled back to the mixed acid inlet. The HF obtained from distillation is recycled through the outlet of distillation unit 53 to the impurity removal reactor in the raw material treatment process to remove impurities such as SiO₂, CaCO₃, and Ca(OH)₂ from the fluorine-containing sludge.

[0098] The fluorine-containing gas first comes into full contact with the circulating washing liquid in the pre-washing tower 51, where larger particles, some acid mist, and high-temperature heat are rapidly removed. The gas then enters the main washing tower 52 for further contact with the acid spray, where residual fine particles, soluble impurities, and entrained moisture are further removed. The contaminated washing liquid then enters the distillation unit 53 from the pre-washing tower 51, where it is evaporated and separated to obtain recoverable acid, which is then returned to the pre-washing tower 51 and the feeding mechanism 12. Acid at the bottom of the main washing tower 52 or at the acid outlet can also flow back to the top of the tower and replenish the pre-washing tower 51, thus maintaining a stable washing liquid concentration and spraying state. This synergistic approach of segmented washing and distillation recovery allows for rapid cooling and coarse purification of the high-temperature fluorine-containing gas at the front end, reducing the load on subsequent towers and enabling the recycling of the washing medium, thereby reducing acid consumption and emission pressure.

[0099] Furthermore, the acid outlet of the demister 56 is also connected to the acid storage tank at the bottom of the main scrubbing tower 52, for transporting the acid in the demister 56 to the acid storage tank of the main scrubbing tower 52.

[0100] In some embodiments, the distillation apparatus 60 is used to separate and purify gases. The distillation apparatus 60 includes a first distillation column 61, a first condenser column 62, a second distillation column 63, a second condenser column 64, an absorption column 65, and a filter assembly 66. The feed inlet of the first distillation column 61 is connected to the washing device 50. The first distillation column 61, the second distillation column 63, the second condenser column 64, the absorption column 65, and the filter assembly 66 are connected in sequence. The top outlet of the first distillation column 61 is also connected to the first condenser column 62.

[0101] In some embodiments, the outlet of the second condenser 64 is connected to the bottom of the first distillation column 61.

[0102] In some embodiments, the outlet of the first condenser 62 is connected to the bottom of the first distillation column 61.

[0103] The material and gas flowing out of the demister 56 enter from the bottom of the first distillation column 61. The reflux ratio at the top of the first distillation column 61 is controlled at 2~5, and the column is under positive pressure. The material is separated by the trays of the first distillation column 61. The light component at the top of the first distillation column 61 enters the first condenser 62, and the liquid at the top of the first distillation column 61 falls back into the storage tank of the first distillation column 61. The liquid in the storage tank of the first distillation column 61 is heated and evaporated, and the liquid and the material in the column form a circulation reflux. The liquid obtained in the storage tank of the first distillation column 61 is high-purity HF condensate with a purity of 99.98~99.99%. The light component in the first distillation column 61 is condensed in the first condenser 62. The non-condensable tail gas components are SO2 and SiF4, which are absorbed by water and lime water in sequence to obtain the byproducts fluorosilicic acid and calcium sulfate. The liquid part is pumped back into the first distillation column 61.

[0104] The liquid in the storage tank of the first distillation column 61 enters the second distillation column 63. After being heated in the reboiler of the second distillation column 63, it vaporizes, condenses, and refluxes within the column. The reflux ratio at the top of the second distillation column 63 is controlled at 1~3. The liquid at the top of the second distillation column 63 falls back into the storage tank of the second distillation column 63. The liquid in the storage tank of the second distillation column 63 is heated and evaporated, forming a circulation reflux with the material in the column. The light components at the top of the second distillation column 63 enter the second condenser 64, and the gas phase is introduced into the absorption column 65 for absorption. The liquid portion is pumped back into the first distillation column 61 for re-reflux purification. High-purity water with a resistivity ≥18.0 MΩ·cm is sprayed at the top of the absorption column 65, and the spray density is controlled to uniformly absorb HF gas. The absorbent falls into the bottom of the tower and is a semi-finished electronic-grade hydrofluoric acid. It is filtered through the 0.2μm microporous membrane and the 0.05μm microporous membrane of the filter assembly 66 to obtain ultra-high purity electronic-grade hydrofluoric acid with impurity ion concentration ≤25ppm and particle number (≥0.2um) ≤25ea / mL.

[0105] The first distillation column 61 has a storage tank temperature of 30-45℃ and a top temperature of 15-20℃. The first condenser column 62 has a condensation temperature of 10-15℃. The second distillation column 63 has a bottom temperature of 35-45℃, and the second condenser column 64 has a temperature of 20-35℃. A high-purity water spray nozzle is installed above the absorption column 65. The filter assembly 66 is equipped with a primary 0.2μm microporous membrane and a secondary 0.05μm microporous membrane.

[0106] The first distillation column 61 is a column used for preliminary distillation separation of the washed fluorine-containing medium. The first condenser column 62 is a condensation unit that forms a reflux loop with the first distillation column 61. The second distillation column 63 is a deep distillation column used to further improve the separation purity. The second condenser column 64 is a condensation unit used to recondense the intermediate product stream and participate in reflux regulation. The absorber column 65 is a gas-liquid absorption device used to absorb residual light components or trace amounts of acid mist. The filter assembly 66 is a terminal purification unit used to remove particles, droplets, and extremely fine impurities. The feed inlet of the distillation column is connected to the washing device 50, allowing the material after pre-washing and main washing to enter the distillation system. The first distillation column 61, the second distillation column 63, the second condenser column 64, the absorber column 65, and the filter assembly 66 are connected sequentially to form a continuous process chain from preliminary separation to deep purification and then to terminal filtration. The top outlet of the first distillation column 61 is also connected to the first condenser column 62, allowing the top vapor to be refluxed back to the bottom of the column after condensation to stabilize the reflux ratio within the column. The outlet of the first condenser 62 is connected to the bottom of the first distillation column 61, and the outlet of the second condenser 64 is also connected to the bottom of the first distillation column 61. This multi-stage condensation and reflux process enables repeated enrichment and re-separation of components within the columns. Through the combined action of multi-stage distillation, condensation and reflux, absorption, and filtration, the residual amounts of volatile impurities, acid mist, and solid particles can be effectively reduced, improving the stability and consistency of electronic-grade hydrofluoric acid. Furthermore, the front-end washing and recovery process is coordinated with the back-end refining process, forming a continuous, closed, and easily controllable preparation process. It should be understood that the above examples are merely illustrative and not limiting. Without departing from the overall concept of this application, the column form, connection method, condensation method, and filtration structure can be replaced or equivalently transformed accordingly.

[0107] Furthermore, this application also provides a method for preparing high-purity hydrofluoric acid from fluorinated sludge, applied to a device 100 for preparing high-purity hydrofluoric acid from fluorinated sludge based on directional separation and purification, comprising the following steps: fluorinated sludge powder and mixed acid are respectively fed into a pre-reaction device 10 for mixing, and the fluorinated sludge powder and mixed acid undergo a primary reaction in the pre-reaction device 10; the mixture after the primary reaction is conveyed to a reactor 20, and gas is conveyed into the reactor 20 to mix the mixture a second time and undergo a secondary reaction; the hydrogen fluoride gas generated from the primary and secondary reactions is conveyed to a washing device 50 for washing and impurity removal; the washed and impurity-removed hydrogen fluoride gas is conveyed to a distillation device 60 for distillation, filtration, and purification.

[0108] By first reacting the fluorinated sludge powder with the mixed acid in the pre-reaction unit 10, some of the fluorinated components can be pre-converted, reducing the instantaneous reaction load in the subsequent reactor 20, thereby improving the uniformity and controllability of the feed material. After the primary reaction, the mixture enters the reactor 20, where it undergoes secondary mixing and reaction via the gas source component 30. This ensures more efficient mass and heat transfer within the furnace, promoting continuous release of hydrogen fluoride and reducing localized stagnation. The generated hydrogen fluoride gas is then sequentially fed into the scrubbing unit 50 and the distillation unit 60, gradually removing acid mist, dust, and associated impurities. This improves the purity of hydrofluoric acid, recovery efficiency, and system operational stability.

[0109] This application utilizes the differences in gas density, temperature, and pressure to construct a negative pressure gradient device, forming a stable axial and radial pressure gradient, thereby achieving a dual-effect flow field for precise separation of SiF4 and HF gases and avoiding impurity entrainment.

[0110] This application employs a tandem and synergistic system of pre-washing and rapid cooling for impurity removal, and main washing for deep impurity removal. This system avoids high-temperature corrosion of equipment and extends its service life. The main washing tower removes impurities at a depth of 52, ensuring the purity of HF entering the distillation system.

[0111] This application presents a multi-stage distillation-precision filtration coupled purification process. Through step-by-step purification and filtration, the purity, impurities and particle size of the product are precisely controlled. The distillation tail gas is absorbed and treated to obtain fluorosilicic acid and calcium sulfate byproducts, achieving synergistic recovery of main and byproducts.

[0112] This application features a full-process acid recycling design that reuses pre-washed distilled acid and HF for spraying and raw material impurity removal, while the main washing acid is recycled and sprayed. Mixed acid is blended and combined with acid recovery, and multi-stage distillation acid is reused, which significantly reduces the amount of sulfuric acid and hydrofluoric acid used, avoids acid waste and environmental pressure, and balances economic efficiency and environmental protection.

[0113] Finally, it should be noted that other embodiments of this application will readily conceive of by those skilled in the art upon consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and alterations may be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A device for preparing high-purity hydrofluoric acid from fluoride-containing sludge based on directional separation and purification, characterized in that, It includes a pre-reaction device (10), a reactor (20), a washing device (50), and a distillation device (60) connected in sequence. The reactor (20) is provided with a first air inlet (22), a second air inlet (23) and a feed inlet at the first end, which are connected to the furnace cavity (21). The second air inlet (23) surrounds the first air inlet (22), and the feed inlet corresponds to the second air inlet (23). The reactor (20) is provided with a first gas outlet (24) and a second gas outlet (25) at the first end and the tail end, respectively. The second gas outlet (25) is connected to the washing device (50). The furnace cavity (21) is also provided with a flow guiding component (40). The flow guiding component (40) is used to block the gas at the tail end of the furnace cavity from flowing back to the first end, and at the same time separate the airflow between the low temperature zone at the first end of the furnace cavity and the high temperature zone at the tail end of the furnace cavity, gather the gas at the tail end of the furnace cavity and guide it to the second gas outlet. It also includes a gas source component (30) and a gas collection device. The gas source component (30) is connected to the first air inlet (22) and the second air inlet (23) respectively. The gas collection device is connected to the first air outlet (24). The gas source component (30) is used to deliver negative pressure airflow to the first air inlet (22) and high temperature airflow to the second air inlet (23).

2. The apparatus for preparing high-purity hydrofluoric acid from fluoride-containing sludge based on directional separation and purification according to claim 1, characterized in that, A flow stabilizer is provided at the first air inlet (22), and the flow stabilizer is evenly distributed with multiple air holes.

3. The apparatus for preparing high-purity hydrofluoric acid from fluoride-containing sludge based on directional separation and purification according to claim 1, characterized in that, The first air inlet (22) has a circular cross-section, and the second air inlet (23) has an annular cross-section. The first air inlet (22) and the second air inlet (23) are coaxially arranged, and the cross-sectional area of ​​the first air inlet (22) is smaller than that of the second air inlet (23).

4. The apparatus for preparing high-purity hydrofluoric acid from fluoride-containing sludge based on directional separation and purification according to claim 1, characterized in that, The flow guiding assembly (40) includes a first flow guiding plate (41), which is arranged in a ring in the furnace cavity (21) and corresponds to the second air inlet (23). The first flow guiding plate (41) is inclined along the tail end of the reactor (20) in the direction towards the middle region of the furnace cavity (21).

5. The apparatus for preparing high-purity hydrofluoric acid from fluoride-containing sludge based on directional separation and purification according to claim 4, characterized in that, The tilt angle of the first guide plate (41) is 30°-45°.

6. The apparatus for preparing high-purity hydrofluoric acid from fluoride-containing sludge based on directional separation and purification according to claim 4, characterized in that, The flow guiding assembly (40) includes a plurality of second flow guiding plates (42), which are arranged in a ring shape. The plurality of second flow guiding plates (42) are coaxially arranged and spaced apart along the direction toward the tail end of the reactor (20). The outer diameter and inner diameter of the plurality of second flow guiding plates (42) gradually decrease along the direction toward the tail end of the reactor (20).

7. The apparatus for preparing high-purity hydrofluoric acid from fluoride-containing sludge based on directional separation and purification according to claim 1, characterized in that, The pre-reaction device (10) includes a housing (11) and a feeding mechanism (12). The housing (11) has a cavity, a connecting port and a vent. The connecting port and the vent are respectively connected to the cavity. The connecting port is connected to the feed port. The vent is connected to the washing device (50). The feeding mechanism (12) is partially located in the cavity. The feeding mechanism (12) is used to transport raw materials to the cavity and to transport materials in the cavity to the feed port.

8. The apparatus for preparing high-purity hydrofluoric acid from fluoride-containing sludge based on directional separation and purification according to claim 7, characterized in that, The washing device (50) is used to remove impurities and purify the gas. The washing device (50) includes a pre-washing tower (51), a main washing tower (52), and a distillation device (53). The inlet of the pre-washing tower (51) is connected to the gas guide port and the second gas outlet (25). The outlet of the pre-washing tower (51) is connected to the inlet of the main washing tower (52). The outlet of the pre-washing tower (51) is connected to the distillation device (53).

9. The apparatus for preparing high-purity hydrofluoric acid from fluoride-containing sludge based on directional separation and purification according to claim 8, characterized in that, The acid outlet of the distillation apparatus (53) is connected to the acid inlet of the pre-washing tower (51) for supplying acid to the pre-washing tower (51); The acid outlet of the distillation device (53) is also connected to the mixed acid inlet of the feeding mechanism (12) in the pre-reaction device (10) for supplying acid to the pre-reaction device (10).

10. The apparatus for preparing high-purity hydrofluoric acid from fluoride-containing sludge based on directional separation and purification according to claim 8, characterized in that, The washing device (50) also includes an acid distribution pump (57) and a mixed acid tank (58) connected in sequence. The acid outlet of the main washing tower (52) is connected to the acid inlet of the pre-washing tower (51) through the acid distribution pump (57) and the mixed acid tank (58).

11. The apparatus for preparing high-purity hydrofluoric acid from fluoride-containing sludge based on directional separation and purification according to claim 8, characterized in that, The washing device (50) also includes a circulating pump (54) and a condenser (55) connected in sequence. The acid outlet of the main washing tower (52) is connected to the acid inlet of the main washing tower (52) through the circulating pump (54) and the condenser (55).

12. The apparatus for preparing high-purity hydrofluoric acid from fluoride-containing sludge based on directional separation and purification according to claim 8, characterized in that, The washing device (50) also includes a demister (56), the gas outlet of the main washing tower (52) is connected to the demister (56), the gas outlet of the demister (56) is connected to the distillation device (60), and the acid outlet of the demister (56) is connected to the bottom of the main washing tower (52).

13. The apparatus for preparing high-purity hydrofluoric acid from fluoride-containing sludge based on directional separation and purification according to claim 1, characterized in that, The distillation apparatus (60) is used to separate and purify gas. The distillation apparatus (60) includes a first distillation column (61), a first condenser column (62), a second distillation column (63), a second condenser column (64), an absorption column (65), and a filter assembly (66). The feed inlet of the first distillation column (61) is connected to the washing device (50). The first distillation column (61), the second distillation column (63), the second condenser column (64), the absorption column (65), and the filter assembly (66) are connected in sequence. The top outlet of the first distillation column (61) is also connected to the first condenser column (62).

14. The apparatus for preparing high-purity hydrofluoric acid from fluoride-containing sludge based on directional separation and purification according to claim 13, characterized in that, The outlet of the second condenser (64) is connected to the bottom of the first distillation column (61); the outlet of the first condenser (62) is connected to the bottom of the first distillation column (61).

15. A method for preparing high-purity hydrofluoric acid from fluorinated sludge, comprising using the apparatus for preparing high-purity hydrofluoric acid from fluorinated sludge based on directional separation and purification as described in any one of claims 1-14, characterized in that, Includes the following steps: Fluorine-containing sludge powder and mixed acid are respectively added into the pre-reaction device (10) for mixing, and the fluorine-containing sludge powder and mixed acid undergo a single reaction in the pre-reaction device (10); The mixture after the first reaction is transported into the reactor (20). Negative pressure airflow is introduced into the first air inlet (22) of the reactor (20), and high temperature airflow is introduced into the second air inlet (23) of the reactor (20) to mix the mixture a second time and carry out a second reaction. The hydrogen fluoride gas generated from the primary and secondary reactions is sent to a washing device (50) for washing and impurity removal; The washed and purified hydrogen fluoride gas is sent to the distillation unit (60) for distillation, filtration and purification.

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