A device for purifying rare earth slurry decomposition fluorine-containing tail gas

Abstract

This utility model discloses a device for purifying fluorine-containing tail gas from rare earth slurry decomposition, comprising an acid removal device, a condensation device, and a cooling water system. The acid removal device is a tower structure, with a fluorine-containing tail gas inlet at the bottom and an outlet at the top. The fluorine-containing tail gas inlet is connected to the rare earth slurry reaction vessel, and a packing layer is installed inside the acid removal device. The condensation device has a first outlet at the bottom, which is connected to the top of the acid removal device, and the outlet is connected to the top of the condensation device. The top of the cooling water system is connected to the top of the condensation device, and the bottom of the cooling water system is connected to the bottom of the condensation device. This utility model can separate gases such as hydrofluoric acid and silicon tetrafluoride from sulfuric acid mist, purify fluorine-containing tail gas from rare earth concentrate slurry decomposition, and solve the problem of sulfuric acid mist entrained in the tail gas during the sulfuric acid slurry decomposition of rare earth concentrate.

Description

Technical Field

[0001] This utility model relates to the field of exhaust gas purification technology, and in particular to a device for purifying rare earth slurry decomposition fluorine-containing exhaust gas. Background Technology

[0002] Common mineral-type rare earth ores mainly include three types: bastnaesite, monazite, and mixed rare earth concentrates. Bastnaesite is a mineral containing rare earth fluorocarbonates, while monazite is a mineral containing rare earth phosphates. Current technology mainly uses high-temperature roasting with concentrated sulfuric acid for decomposition, with a decomposition temperature of around 500℃ and a mineral-to-acid ratio of 1:1.2–1.4. During roasting, a large amount of sulfur- and fluorine-containing gases are generated, requiring multi-stage spraying and vacuum distillation to recover the sulfuric acid and fluorosilicic acid mixture. The tail gas recovery process is lengthy and energy-intensive.

[0003] To address the problem of sulfuric acid mist entrained in the tail gas during the sulfuric acid slurry decomposition of rare earth concentrates, a device for purifying fluorine-containing tail gas from the rare earth slurry decomposition is proposed. Utility Model Content

[0004] The purpose of this invention is to provide a device for purifying rare earth slurry decomposition fluorine-containing tail gas, aiming to solve or improve at least one of the above-mentioned technical problems.

[0005] To achieve the above objectives, this utility model provides the following solution: This utility model provides a device for purifying rare earth slurry decomposition fluorine-containing tail gas, comprising:

[0006] An acid removal device is a tower-type structure. The bottom of the acid removal device is provided with a fluorine-containing tail gas inlet, and the top of the acid removal device is provided with a gas outlet. The fluorine-containing tail gas inlet is connected to a rare earth slurry reaction vessel, and a packing layer is installed inside the acid removal device.

[0007] A condensing device, wherein the bottom of the condensing device is provided with a first outlet, the first outlet is connected to the top of the acid removal device, and the air outlet is connected to the top of the condensing device;

[0008] A cooling water system, the top of which is connected to the top of the condensing equipment, and the bottom of which is connected to the bottom of the condensing equipment.

[0009] According to the present invention, a device for purifying rare earth slurry decomposition fluorine-containing tail gas is provided, wherein the acid removal equipment is a steel-lined acid removal equipment or a graphite acid removal equipment.

[0010] According to the present invention, a device for purifying rare earth slurry decomposition fluorine-containing tail gas is provided, wherein the condensation equipment is a silicon carbide condenser or an impregnated graphite condenser.

[0011] According to the present invention, a device for purifying rare earth slurry decomposition fluorine-containing tail gas is provided, wherein the bottom of the condensation device is higher than the top of the acid removal device.

[0012] According to the present invention, a device for purifying rare earth slurry decomposition fluorine-containing tail gas is provided, wherein the top of the cooling water system is fixedly connected to and communicates with the top of the condensing equipment through a first pipe, and the bottom of the cooling water system is fixedly connected to and communicates with the bottom of the condensing equipment through a second pipe; a first valve is installed on the first pipe, and a second valve is installed on the second pipe.

[0013] The present invention discloses the following technical effects:

[0014] In use, the fluorine-containing exhaust gas enters the acid removal equipment through the fluorine-containing exhaust gas inlet. In the acid removal equipment, the fluorine-containing exhaust gas comes into contact with the condensate. The purified exhaust gas is then discharged through the outlet. After absorbing the sulfuric acid mist, the condensate enters the condensation equipment and is condensed through the cooling water system. It then continues to flow back to the acid removal equipment from the bottom of the condensation equipment. The condensate circulates between the acid removal equipment and the condensation equipment, absorbing the sulfuric acid mist entrained in the exhaust gas. When it reaches a certain concentration, it is discharged from the bottom of the condensation equipment.

[0015] The acid removal equipment in this invention has a tower structure. The internal packing layer promotes the full separation of hydrogen fluoride, silicon tetrafluoride and sulfuric acid mist in the fluorine-containing tail gas, thereby purifying the fluorine-containing tail gas. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of this utility model.

[0018] The components include: 1. Acid removal equipment; 2. Condensation equipment; and 3. Cooling water system. Detailed Implementation

[0019] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0020] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] Reference Figure 1 This utility model provides a device for purifying rare earth slurry decomposition fluorine-containing tail gas, comprising:

[0022] Acid removal equipment 1 has a tower structure. The bottom of the acid removal equipment 1 is provided with a fluorine-containing tail gas inlet, and the top of the acid removal equipment 1 is provided with a gas outlet. The fluorine-containing tail gas inlet is connected to the rare earth slurry reaction vessel. A packing layer is installed inside the acid removal equipment 1.

[0023] Condensing device 2, the bottom of condensing device 2 is provided with a first outlet, the first outlet is connected to the top of acid removal device 1, and the air outlet is connected to the top of condensing device 2.

[0024] Cooling water system 3, the top of cooling water system 3 is connected to the top of condensing equipment 2, and the bottom of cooling water system 3 is connected to the bottom of condensing equipment 2;

[0025] With this setup, the present invention utilizes the fact that there is no sulfuric acid decomposition during the decomposition of rare earth minerals, and the main components of the fluorine-containing tail gas are hydrofluoric acid and silicon tetrafluoride, with a temperature between 100℃ and 140℃. The fluorine-containing tail gas enters the acid removal equipment 1 through the fluorine-containing tail gas inlet. In the acid removal equipment 1, the fluorine-containing tail gas comes into contact with the condensate, and the purified tail gas is discharged through the outlet. After absorbing the sulfuric acid mist, the condensate enters the condensation equipment 2 and is condensed by the cooling water system 3. Then, it continues to flow back to the acid removal equipment 1 from the bottom of the condensation equipment 2. The condensate circulates in the acid removal equipment 1 and the condensation equipment, absorbing the sulfuric acid mist entrained in the tail gas. After reaching a certain concentration, it is discharged from the bottom of the condensation equipment 2.

[0026] In this invention, the acid removal device 1 has a tower structure. The internal packing layer promotes the full separation of hydrogen fluoride, silicon tetrafluoride and sulfuric acid mist in the acid removal device 1, thereby purifying the fluoride-containing exhaust gas.

[0027] Further optimization of the scheme involves the use of several irregularly shaped packing materials in the packing layer of the acid removal equipment 1. After the fluorine-containing exhaust gas enters the acid removal equipment 1, it flows upward through the packing layer. Due to the irregular shape of the packing material, its surface has numerous complex and irregular protrusions, depressions, and tortuous channels. When the exhaust gas encounters the condensate flowing back from the bottom of the condensation equipment 2 in the packing layer, the irregularly shaped packing material greatly increases the contact area between the exhaust gas and the condensate. As the exhaust gas flows through the tortuous channels of the packing material, its flow path becomes complex and extended, allowing harmful components such as sulfuric acid mist in the exhaust gas to have more opportunities to fully contact and be absorbed by the condensate. At the same time, the irregular packing material can also generate a certain turbulence effect, promoting the mixing and mass transfer process between the exhaust gas and the condensate, further improving the absorption efficiency of sulfuric acid mist, and thus more effectively purifying the fluorine-containing exhaust gas.

[0028] Further optimize the solution by using either a steel-lined acid removal device or a graphite acid removal device for the acid removal equipment 1.

[0029] The steel-lined acid removal equipment is made of PTFE steel. The steel outer shell of the equipment is lined with a layer of corrosion-resistant material (such as rubber or plastic). When fluorine-containing exhaust gas enters the steel-lined acid removal equipment, it reacts with the internal condensate. Acidic substances such as sulfuric acid mist in the exhaust gas can corrode the equipment. The steel outer shell provides overall strength and stability, allowing it to withstand certain pressure and temperature changes. The internal corrosion-resistant lining directly contacts the exhaust gas and condensate, effectively preventing acidic substances from corroding the steel outer shell. This ensures the equipment will not be damaged by corrosion during long-term operation, thus ensuring the continuous and stable operation of the acid removal process and extending the equipment's service life.

[0030] The graphite acid removal equipment is made of graphite. Utilizing graphite's excellent corrosion resistance and thermal conductivity, when fluorine-containing exhaust gas enters the equipment, acidic substances such as sulfuric acid mist react with the condensate inside. The graphite material resists the corrosive effects of these acidic substances and is not damaged by the chemical reaction. Simultaneously, graphite's thermal conductivity helps dissipate the heat generated during the reaction, maintaining a stable internal temperature and preventing excessive heat from affecting the acid removal effect or damaging the equipment. Furthermore, graphite possesses a certain degree of chemical stability, preventing unnecessary side reactions with the exhaust gas and condensate, thus ensuring the reliability and purification effect of the acid removal process.

[0031] Further optimize the scheme, the condensing equipment 2 is a silicon carbide condenser or an impregnated graphite condenser;

[0032] The silicon carbide condenser utilizes the high thermal conductivity and corrosion resistance of silicon carbide material. When the purified exhaust gas enters the silicon carbide condenser from the top of the acid removal equipment 1, it exchanges heat with the cooling medium (usually cooling water) inside the condenser. The silicon carbide material can quickly transfer the heat in the exhaust gas to the cooling medium, causing the water vapor and other components in the exhaust gas to condense rapidly into a liquid state. At the same time, the corrosion resistance of silicon carbide ensures that the condenser will not be corroded when in contact with exhaust gas containing acidic substances, thus enabling long-term stable operation and effectively condensing the water vapor in the exhaust gas, achieving further purification and cooling of the exhaust gas.

[0033] Impregnated graphite condensers are made by impregnating graphite material with special resins and other substances to improve its strength and sealing performance. When exhaust gas enters the impregnated graphite condenser, it exchanges heat with the internal cooling medium. The impregnated graphite material not only retains the original corrosion resistance of graphite but also enhances its mechanical properties, enabling it to withstand certain pressure and temperature changes. During the heat exchange process, the impregnated graphite condenser efficiently transfers heat from the exhaust gas to the cooling medium, causing water vapor in the exhaust gas to condense, while preventing exhaust gas leakage, ensuring the smooth progress of the condensation process, effectively reducing the exhaust gas temperature and removing some moisture.

[0034] The design is further optimized so that the bottom of the condenser 2 is higher than the top of the acid removal device 1. This height difference utilizes the principle of gravity, allowing the condensate accumulated in the condenser 2 to automatically flow back to the acid removal device 1 from the first outlet at the bottom of the condenser 2 under the action of gravity, forming a circulating flow of condensate. No additional power equipment is needed to drive the condensate return, reducing energy consumption and equipment costs. At the same time, the natural flow method can ensure the stability of the condensate flow and avoid the condensate return being obstructed due to power equipment failure or other reasons. This ensures that the condensate circulation between the acid removal device 1 and the condenser 2 remains smooth, continuously and effectively purifying and treating the fluorinated exhaust gas.

[0035] Further optimization of the scheme: the top of the cooling water system 3 is fixedly connected to the top of the condensing equipment 2 through the first pipe and is connected to the bottom of the condensing equipment 2 through the second pipe; a first valve is installed on the first pipe and a second valve is installed on the second pipe;

[0036] The first valve and the second valve can control the flow of cooling water between the cooling water system 3 and the condensing equipment 2 respectively. During normal operation, both the first valve and the second valve are open. Cooling water flows from the top of the cooling water system 3 into the top of the condensing equipment 2 through the first pipe to cool the exhaust gas entering the condensing equipment 2. After absorbing the heat in the exhaust gas, the temperature of the cooling water rises and flows out from the bottom of the condensing equipment 2. It then returns to the bottom of the cooling water system 3 through the second pipe, forming a circulating flow of cooling water to ensure the cooling effect of the condensing equipment 2.

[0037] When maintenance, repair, or adjustment of the cooling water system's flow rate is required, the connection between the cooling water system 3 and the condensing equipment 2 can be severed by closing the first and second valves, stopping the circulation of cooling water. This facilitates related operations by personnel without affecting the normal operation of other parts of the entire unit. Simultaneously, by adjusting the opening of the first and second valves, the flow rate of the cooling water can be controlled, optimizing the cooling effect based on actual operating conditions and improving the unit's operating efficiency and stability.

[0038] To further optimize the solution, a gas distributor is installed at the fluorine-containing tail gas inlet at the bottom of the acid removal equipment 1. The gas distributor can evenly disperse the fluorine-containing tail gas entering from the rare earth slurry reactor onto the cross-section of the acid removal equipment 1, avoiding the tail gas from concentrating in a local area, and allowing the tail gas to come into more full contact with the packing layer and condensate, thereby improving the acid removal efficiency.

[0039] To further optimize the solution, a filter screen is installed above the gas distributor to intercept large particulate impurities that may be carried in the exhaust gas, preventing these impurities from entering the acid removal equipment 1, clogging the packing layer, or causing wear to the equipment, thus extending the service life of the equipment.

[0040] In the description of this utility model, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model 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. Therefore, they should not be construed as limitations on this utility model.

[0041] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. For those skilled in the art, other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A device for purifying fluorine-containing tail gas from rare earth slurry decomposition, characterized in that, include: Acid removal equipment (1) is a tower structure. The bottom of the acid removal equipment (1) is provided with a fluorine-containing tail gas inlet, and the top of the acid removal equipment (1) is provided with a gas outlet. The fluorine-containing tail gas inlet is connected to a rare earth slurry reaction vessel. A packing layer is installed inside the acid removal equipment (1). A gas distributor is installed at the fluorine-containing tail gas inlet at the bottom of the acid removal equipment (1), and a filter screen is installed above the gas distributor. The condensing device (2) has a first outlet at its bottom, which is connected to the top of the acid removal device (1), and the air outlet is connected to the top of the condensing device (2). Cooling water system (3), the top of which is connected to the top of the condensing device (2), and the bottom of which is connected to the bottom of the condensing device (2).

2. The apparatus for purifying rare earth slurry decomposition of fluorine-containing tail gas according to claim 1, characterized in that: The acid removal equipment (1) is a steel-lined acid removal equipment or a graphite acid removal equipment.

3. The apparatus for purifying rare earth slurry decomposition of fluorine-containing tail gas according to claim 1, characterized in that: The condensing device (2) is a silicon carbide condenser or an impregnated graphite condenser.

4. The apparatus for purifying rare earth slurry decomposition of fluorine-containing tail gas according to claim 1, characterized in that: The bottom of the condensing device (2) is higher than the top of the acid removal device (1).

5. The apparatus for purifying rare earth slurry decomposition of fluorine-containing tail gas according to claim 1, characterized in that: The top of the cooling water system (3) is fixedly connected to and communicates with the top of the condensing device (2) through a first pipe, and the bottom of the cooling water system (3) is fixedly connected to and communicates with the bottom of the condensing device (2) through a second pipe; a first valve is installed on the first pipe, and a second valve is installed on the second pipe.

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