A system and method for synergistic disposal of spent cathode carbon blocks

Abstract

The application discloses a kind of waste cathode carbon block's collaborative disposal system and disposal method, and the system includes crushing and grinding device, mixing device, suspension reactor, heat supply system, gas-solid separation device, condensation collection device, water washing device, filtration device and waste liquid treatment pool.Wherein, by utilizing the high-temperature flue gas of heat supply system bypass air release, the low-cost heat treatment of waste cathode carbon block is realized;And waste cathode carbon block can be converted into gaseous fluorine-containing sodium salt in fluoride direction, and the fluorine-rich kiln dust can be captured by condensation, and the recovery of fluorine element is realized;At the same time, carbon powder is obtained by screening through filtration device, and the recycling of carbon resources is realized.

Description

Technical Field

[0001] This invention relates to the field of co-processing hazardous waste in cement kilns, and particularly to a co-processing system and method for waste cathode carbon blocks. Background Technology

[0002] The electrolytic aluminum industry generates a large amount of waste cathode carbon blocks during production. Statistics show that approximately 100 tons of waste cathode carbon blocks are produced for every 10,000 tons of primary aluminum produced. Carbon accounts for 50-70% of these waste cathode carbon blocks, with other components including cryolite, sodium fluoride, and calcium fluoride. Because these cathode carbon blocks contain highly leaching fluorides, their harmless and resource-efficient disposal is one of the urgent problems that the industry needs to solve.

[0003] For large-scale industrial application, existing technologies have developed direct utilization schemes using fluorine as an alternative fuel for cement kilns. However, this process has significant limitations. Valuable elements in the cathode carbon blocks are introduced into the kiln system as a whole, and elements such as fluorine are easily volatilized at high temperatures. This can not only generate corrosive and toxic gases such as HF, but also form a circulating accumulation in the kiln tail preheating system, leading to scaling and blockage, which seriously affects the stable operation of the cement kiln and the compliance of pollutant emissions. To reduce the hazards of fluorine, existing technologies have also developed fluorine-fixing or impurity-removal schemes for pre-treating waste cathodes. However, their industrial applicability is often limited, and their processes are complex, involve many steps, have high energy consumption, and involve the use of strong acids and fluorides, requiring high equipment corrosion resistance. Subsequent wastewater treatment also brings additional environmental and cost pressures. Therefore, this process is difficult to adapt to the large-scale, continuous, and low-cost fuel replacement scenario for cement kilns.

[0004] In summary, existing technologies cannot overcome the core bottlenecks for large-scale industrial application, mainly in the following aspects: 1) the impact of fluorine on cement kiln systems has not been effectively addressed; 2) the high costs and secondary pollution associated with existing pretreatment methods. Therefore, the industry urgently needs an integrated solution that can remove fluorine at low cost and achieve product synergy, in order to realize the large-scale high-value conversion of waste cathodes in cement kiln systems. Summary of the Invention

[0005] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. To this end, this application proposes a co-processing system for waste cathode carbon blocks, which can capture and recover fluorine, and the processing reduces energy consumption.

[0006] This application also proposes a disposal method based on the aforementioned co-processing system for waste cathode carbon blocks.

[0007] A co-processing system for waste cathode carbon blocks according to a first aspect embodiment of this application includes: Crushing and grinding device, used to crush and grind waste cathode carbon blocks; A mixing device connected to the crushing and grinding device to receive the ground cathode carbon powder, the mixing device being capable of feeding sodium carbonate powder to mix with the cathode carbon powder; A suspension reactor connected to the mixing device to receive a mixture of the cathode carbon powder and the sodium carbonate powder; A heat source supply system includes a decomposition furnace, a rotary kiln, and a kiln tail flue. The bypass vent of the kiln tail flue is connected to the suspension reactor. Both the decomposition furnace and the rotary kiln are connected to the kiln tail flue. A gas-solid separation device is connected to the outlet of the suspension reactor, and the gas-solid separation device is used to separate solids and gases; A condensation collection device is connected to the gas outlet of the gas-solid separation device; A water washing device is connected to the solid discharge port of the gas-solid separation device; A filtration device, which is connected to the outlet of the washing device, is used to filter out carbon powder.

[0008] A waste liquid treatment tank, which is connected to the waste liquid outlet of the filtration device, is used to recover the concentrated product of sodium carbonate solution.

[0009] The co-processing system for waste cathode carbon blocks according to the embodiments of this application has at least the following beneficial effects: by utilizing the high-temperature flue gas of the decomposition furnace, low-cost thermal treatment of waste cathode carbon blocks can be achieved without additional energy consumption; moreover, the fluorides in the waste cathode carbon blocks can be directionally converted into gaseous sodium fluoride salts, which can be condensed to obtain fluorine-rich kiln ash that can be captured, thereby recovering fluorine elements and reducing the impact on the environment; at the same time, carbon powder can be obtained by screening through a filtration device, thereby realizing the reuse of carbon resources.

[0010] According to some embodiments of this application, a gas distribution plate is provided between the suspension reactor and the kiln tail flue, and the gas distribution plate is provided with multiple grids to homogenize the flue gas velocity.

[0011] According to some embodiments of this application, the washing device is provided with a stirring mechanism.

[0012] According to some embodiments of this application, a cooling fan is further provided between the suspension reactor and the gas-solid separation device, and the cooling fan is used to cool the mixed gas produced by the suspension reactor.

[0013] According to some embodiments of this application, a gas distributor is provided in the waste liquid treatment tank, and the gas distributor injects carbon dioxide-containing flue gas into the waste liquid treatment tank.

[0014] The disposal method according to the second aspect of this application, which is based on the above-described co-processing system for waste cathode carbon blocks, includes the following steps: Waste cathode carbon blocks are fed into the crushing and grinding device for crushing and grinding to obtain cathode carbon powder; The cathode carbon powder enters the mixing device to be mixed with sodium carbonate powder, and the mixed material enters the suspension reactor. The high-temperature flue gas from the bypass vent of the heat source supply system enters the suspension reactor and reacts with the mixture of cathode carbon powder and sodium carbonate powder to obtain a mixed gas after the reaction. The gas-solid separation device receives the mixed gas produced from the suspension reactor and separates the solids from the gas; The gas produced by the gas-solid separation device enters the condensation and collection device for condensation, causing the fluorides therein to condense, precipitate, and be collected. The solid produced by the gas-solid separation device enters the water washing device, where sodium aluminate in the solid dissolves into the liquid phase, and the carbon powder in the solid continues to be suspended in a solid state. The filtration device filters the product of the washing device to obtain solid carbon powder.

[0015] The waste liquid filtered by the filtration device enters the waste liquid treatment tank, while carbon dioxide flue gas from the condensation and collection device is introduced into the waste liquid treatment tank. The resulting sodium carbonate powder can be fed into the mixing device for recycling.

[0016] According to some embodiments of this application, in the mixing device, the mixing ratio of cathode carbon powder to sodium carbonate powder is 2:1 to 3:1.

[0017] According to some embodiments of this application, the flue gas velocity ejected from the kiln tail flue into the suspension reactor is 8 to 15 m / s.

[0018] According to some embodiments of this application, the temperature of the flue gas produced by the heat source supply system is 1050 to 1150°C, and the oxygen content is 2 to 5%; in the suspension reactor, cryolite and calcium fluoride in the cathode carbon powder react fully with sodium carbonate, and cryolite and calcium fluoride are mainly converted into gaseous sodium fluoride salt sodium fluoride, and some aluminum fluoride and carbon dioxide enter the gas phase, and the solid products are carbon powder and sodium aluminate.

[0019] According to some embodiments of this application, the condensation collection device cools the gas to below 200°C to promote the condensation and precipitation of fluorides.

[0020] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0021] The accompanying drawings are used to provide a further understanding of the technical solutions disclosed in this application and form part of the specification. They are used together with the embodiments disclosed in this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions disclosed in this application.

[0022] Figure 1 This is a schematic diagram of the connection of the co-processing system for waste cathode carbon blocks according to the first aspect of this application.

[0023] Figure reference numerals: 100-crushing and grinding device, 200-mixing device, 300-suspension reactor, 400-heat source supply system, 410-decomposition furnace, 420-kiln tail flue, 430-rotary kiln, 500-gas-solid separation device, 600-condensation and collection device, 700-water washing device, 800-filtration device, 900-cooling fan, 1000-waste liquid treatment tank. Detailed Implementation

[0024] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0025] In the description of this application, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, 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 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. Therefore, they should not be construed as limitations on this application.

[0026] In the description of this application, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0027] In the description of this application, unless otherwise expressly defined, terms such as "setup," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this application in conjunction with the specific content of the technical solution.

[0028] In the description of this application, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0029] The electrolytic aluminum industry generates a large amount of waste cathode carbon blocks during production. Statistics show that approximately 100 tons of waste cathode carbon blocks are produced for every 10,000 tons of primary aluminum produced. Carbon accounts for 50-70% of these waste cathode carbon blocks, with other components including cryolite, sodium fluoride, and calcium fluoride. Because these cathode carbon blocks contain highly leaching fluorides, their harmless and resource-efficient disposal is one of the urgent problems that the industry needs to solve.

[0030] For large-scale industrial application, existing technologies have developed direct utilization schemes using fluorine as an alternative fuel for cement kilns. However, this process has significant limitations. Valuable elements in the cathode carbon blocks are introduced into the kiln system as a whole, and elements such as fluorine are easily volatilized at high temperatures. This can not only generate corrosive and toxic gases such as HF, but also form a circulating accumulation in the kiln tail preheating system, leading to scaling and blockage, which seriously affects the stable operation of the cement kiln and the compliance of pollutant emissions. To reduce the hazards of fluorine, existing technologies have also developed fluorine-fixing or impurity-removal schemes for pre-treating waste cathodes. However, their industrial applicability is often limited, and their processes are complex, involve many steps, have high energy consumption, and involve the use of strong acids and fluorides, requiring high equipment corrosion resistance. Subsequent wastewater treatment also brings additional environmental and cost pressures. Therefore, this process is difficult to adapt to the large-scale, continuous, and low-cost fuel replacement scenario for cement kilns.

[0031] In summary, existing technologies cannot overcome the core bottlenecks for large-scale industrial application, mainly in the following aspects: 1) the impact of fluorine on cement kiln systems has not been effectively addressed; 2) the high costs and secondary pollution associated with existing pretreatment methods. Therefore, the industry urgently needs an integrated solution that can remove fluorine at low cost and achieve product synergy, in order to realize the large-scale high-value conversion of waste cathodes in cement kiln systems.

[0032] In response, this application proposes a co-processing system and a corresponding disposal method for waste cathode carbon blocks. By utilizing the high-temperature flue gas of the decomposition furnace, the waste cathode carbon blocks can be thermally treated at low cost without additional energy consumption. Moreover, the fluorides in the waste cathode carbon blocks can be directionally converted into gaseous sodium fluoride salts, which can be condensed to obtain fluorine-rich kiln ash that can be captured, thereby recovering fluorine and reducing environmental impact.

[0033] Reference Figure 1The co-processing system for waste cathode carbon blocks in the first aspect of this application includes a crushing and grinding device 100, a mixing device 200, a suspension reactor 300, a heat source supply system 400, a gas-solid separation device 500, a condensation and collection device 600, a water washing device 700, a filtration device 800, and a waste liquid treatment tank 1000. The crushing and grinding device 100 is used to crush and grind the whole waste cathode carbon blocks into small particles of cathode carbon powder, facilitating subsequent mixing and reaction. The mixing device 200 is used to mix the cathode carbon powder with sodium carbonate powder. The mixed material enters the suspension reactor 300 for high-temperature reaction. The heat source supply system 400 is used to inject high-temperature flue gas into the suspension reactor 300. The product from the reaction in the suspension reactor 300 enters the gas-solid separation device 500 for gas-solid separation. The gas enters the condensation and collection device 600 for cooling and condensation, causing the fluoride to precipitate and thus collecting the fluorine element. The solid enters the water washing device 700 for washing and then passes through the filtration device 800 to separate the carbon powder, thus recovering the carbon powder. The waste liquid treatment pond collects the waste liquid discharged from the filtration device and is used to recover the concentrated product of the sodium carbonate solution.

[0034] Specifically, the mixing device 200 is connected to the crushing and grinding device 100 to receive the ground cathode carbon powder. The mixing device 200 is provided with a feeding port to feed in sodium carbonate powder, so that the sodium carbonate powder mixes with the cathode carbon powder. The main components of the cathode carbon powder are fixed carbon, cryolite, calcium fluoride, sodium fluoride, and a small amount of electrolyte; the sodium carbonate can be industrial-grade soda ash.

[0035] The suspension reactor 300 is connected to the mixing device 200 to receive a mixture of cathode carbon powder and sodium carbonate powder. The heat supply system 400 includes a decomposition furnace 410, a kiln tail flue chamber 420, and a rotary kiln 430. The decomposition furnace 410 and rotary kiln 430 are common chemical equipment, and their exhaust gases still have a high temperature after the reaction. Both the decomposition furnace 410 and rotary kiln 430 are connected to the kiln tail flue chamber 420, whose bypass vent is connected to the suspension reactor 300. This allows the kiln tail flue chamber 420 to collect the high-temperature flue gas produced by the rotary kiln 430 and output it to the suspension reactor 300. The high-temperature flue gas can be used as a heat source to heat the internal environment of the suspension reactor 300, thereby making full use of existing energy and reducing energy consumption. Inside the suspension reactor 300, the high-temperature flue gas causes the mixture to be blown up and suspended in the airflow, completing the gas-solid reaction at high temperature.

[0036] The gas-solid separation device 500 is connected to the outlet of the suspension reactor 300. The gas-solid separation device 500 is used to separate solids and gases, and it is equipped with a sieve tube capable of filtering solids, thereby achieving the separation of gas and solids. The gas is mainly fluorine-containing flue gas, and the solids are mainly carbon powder and sodium aluminate crystals adhered to the surface of the carbon powder. After separation, the gas is discharged from the gas outlet of the gas-solid separation device 500, and the solids are discharged from the solids outlet of the gas-solid separation device 500.

[0037] A condensation and collection device 600 is connected to the gas outlet of the gas-solid separation device 500. It is used to cool and condense fluorine-containing gas, allowing the fluorides to precipitate and be collected. A water washing device 700 is connected to the solid outlet of the gas-solid separation device 500. It uses water washing to dissolve sodium aluminate on the surface of the carbon powder, separating the sodium aluminate from the carbon powder and improving the purity of the carbon powder. A filtration device 800 is connected to the outlet of the water washing device 700, used to filter out the carbon powder and collect it.

[0038] Wastewater treatment tank 1000 is connected to filter device 800 to receive filtered wastewater. The concentrated sodium carbonate solution in the wastewater can be returned to mixing device 200 to mix with cathode carbon powder, thus enabling the reuse of sodium carbonate powder.

[0039] Furthermore, a gas distribution plate is provided between the flue gas outlet of the suspension reactor 300 and the decomposition furnace 410. The gas distribution plate is provided with multiple grids to homogenize the flue gas flow rate, making the airflow field of the high-temperature flue gas more uniform.

[0040] Furthermore, the washing device 700 is equipped with a stirring mechanism, which enables the sodium aluminate on the surface of the carbon powder to fully dissolve in the water, thereby improving the purity of the carbon powder after subsequent filtration. Specifically, the stirring speed is 60 to 120 rpm, the washing temperature is -60℃, and the washing time is 10 to 30 minutes.

[0041] Furthermore, the solid-liquid ratio in the water washing device 700 is controlled at 1:3 to 1:5 g / ml, and the liquid used for water washing is water.

[0042] Furthermore, a cooling fan 900 is provided between the suspension reactor 300 and the gas-solid separation device 500. The cooling fan 900 is used to cool the mixed gas produced by the suspension reactor 300, so that the gas temperature drops to below 900°C, thereby reducing the damage caused by the high-temperature gas to the gas-solid separation device 500.

[0043] Furthermore, the gas-solid separation device 500 is specifically a high-temperature dust collector, whose filter tube material is resistant to temperatures of 600 to 900°C, and whose filtration velocity is controlled at 0.8 to 1.2 m / min, in order to facilitate the efficient separation of high-temperature fluorine-containing flue gas and solid products.

[0044] Furthermore, a gas distributor is installed in the waste liquid treatment tank 1000. The gas distributor injects carbon dioxide-containing flue gas discharged from the condensation and collection device 600 into the waste liquid treatment tank 1000, so that the sodium aluminate solution in the waste liquid treatment tank 1000 reacts with carbon dioxide to generate aluminum hydroxide byproduct and sodium carbonate solution. The sodium carbonate solution can be recycled after concentration.

[0045] A disposal method according to a second aspect embodiment of this application, which is based on the above-mentioned co-processing system for waste cathode carbon blocks, includes the following steps: S100. Waste cathode carbon blocks are fed into the crushing and grinding device 100 for crushing and grinding to obtain cathode carbon powder; S200. The cathode carbon powder enters the mixing device 200 to be mixed with the sodium carbonate powder, and the mixed liquid enters the suspension reactor 300. S300. The high-temperature flue gas from the decomposition furnace 410 enters the suspension reactor 300 and reacts with the mixture of cathode carbon powder and sodium carbonate powder to obtain the mixed gas after reaction. S400. The gas-solid separation device 500 receives the mixed gas produced from the suspension reactor 300 and separates the solids from the gas; S500. The gas produced by the gas-solid separation device 500 enters the condensation and collection device 600 for condensation, so that the fluoride in it condenses and precipitates out and is collected. S600. The solid produced by the gas-solid separation device 500 enters the water washing device 700, so that the sodium aluminate in the solid dissolves into the liquid phase, and the carbon powder in the solid continues to be suspended in a solid state. S700. Filtering device 800 filters the product from washing device 700 to obtain solid carbon powder.

[0046] S800. The waste liquid filtered by the filter device 800 enters the waste liquid treatment tank 1000. At the same time, carbon dioxide flue gas from the condensation and collection device 600 is introduced into the waste liquid treatment tank 1000. The resulting concentrated sodium carbonate solution product can be fed into the mixing device 200 for recycling.

[0047] Furthermore, in the mixing device, cathode carbon powder and sodium carbonate are uniformly mixed in a ratio of 2:1 to 3:1 to form a mixture.

[0048] Furthermore, an air valve is installed between the suspension reactor 300 and the flue gas outlet of the kiln tail flue gas chamber 420 to control the flue gas velocity at 8 to 15 m / s.

[0049] Furthermore, during the high-temperature reaction in the suspension reactor 300, the temperature of the flue gas produced by the heat source supply system 400 is limited to 1050 to 1150°C, and the oxygen content is 2 to 5%. In the suspension reactor 300, cryolite and calcium fluoride in the cathode carbon powder react fully with sodium carbonate. Cryolite and calcium fluoride are mainly converted into gaseous sodium fluoride salt, sodium fluoride, and some aluminum fluoride and carbon dioxide enter the gas phase. The solid products are carbon powder and sodium aluminate.

[0050] Furthermore, the condensation and collection device 600 cools the gas to below 200°C to promote the condensation and precipitation of fluorides.

[0051] The embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application. Furthermore, unless otherwise specified, the embodiments and features described in the embodiments of this application can be combined with each other.

Claims

1. A co-processing system for waste cathode carbon blocks, characterized in that, include: Crushing and grinding device, used to crush and grind waste cathode carbon blocks; A mixing device connected to the crushing and grinding device to receive the ground cathode carbon powder, the mixing device being capable of feeding sodium carbonate powder to mix with the cathode carbon powder; A suspension reactor connected to the mixing device to receive a mixture of the cathode carbon powder and the sodium carbonate powder; A heat source supply system includes a decomposition furnace, a rotary kiln, and a kiln tail flue. The bypass vent of the kiln tail flue is connected to the suspension reactor. Both the decomposition furnace and the rotary kiln are connected to the kiln tail flue. A gas-solid separation device is connected to the outlet of the suspension reactor, and the gas-solid separation device is used to separate solids and gases; A condensation collection device is connected to the gas outlet of the gas-solid separation device; A water washing device is connected to the solid discharge port of the gas-solid separation device; A filtration device, which is connected to the outlet of the washing device, is used to filter out carbon powder. A waste liquid treatment tank, which is connected to the waste liquid outlet of the filtration device, is used to recover the concentrated product of sodium carbonate solution.

2. The co-processing system for waste cathode carbon blocks according to claim 1, characterized in that: A gas distribution plate is provided between the suspension reactor and the kiln tail flue chamber, and the gas distribution plate is provided with multiple grids to uniformly distribute the flue gas velocity.

3. The co-processing system for waste cathode carbon blocks according to claim 1, characterized in that: A cooling fan is also provided between the suspension reactor and the gas-solid separation device, and the cooling fan is used to cool the mixed gas produced by the suspension reactor.

4. The co-processing system for waste cathode carbon blocks according to claim 1, characterized in that: The washing device is equipped with a stirring mechanism.

5. The co-processing system for waste cathode carbon blocks according to claim 1, characterized in that: A gas distributor is installed in the waste liquid treatment tank, and the gas distributor injects carbon dioxide-containing flue gas from the condensation and collection device into the waste liquid treatment tank.

6. A disposal method, which is carried out based on the co-processing system for waste cathode carbon blocks according to any one of claims 1 to 5, characterized in that, include: Waste cathode carbon blocks are fed into the crushing and grinding device for crushing and grinding to obtain cathode carbon powder; The cathode carbon powder enters the mixing device to be mixed with sodium carbonate powder, and the mixed material enters the suspension reactor. The high-temperature flue gas from the bypass vent of the heat source supply system enters the suspension reactor and reacts with the mixture of cathode carbon powder and sodium carbonate powder to obtain a mixed gas after the reaction. The gas-solid separation device receives the mixed gas produced from the suspension reactor and separates the solids from the gas; The gas produced by the gas-solid separation device enters the condensation and collection device for condensation, causing the fluorides therein to condense, precipitate, and be collected. The solid produced by the gas-solid separation device enters the water washing device, where sodium aluminate in the solid dissolves into the liquid phase, and the carbon powder in the solid continues to be suspended in a solid state. The filtration device filters the product of the washing device to obtain solid carbon powder. The waste liquid filtered by the filtration device enters the waste liquid treatment tank, while carbon dioxide flue gas from the condensation and collection device is introduced into the waste liquid treatment tank. The resulting sodium carbonate powder can be fed into the mixing device for recycling.

7. The treatment method according to claim 6, characterized in that: In the mixing device, the mixing ratio of cathode carbon powder to sodium carbonate powder is 2:1 to 3:

1.

8. The treatment method according to claim 6, characterized in that: The flue gas velocity ejected from the kiln tail flue into the suspension reactor is 8 to 15 m / s.

9. The treatment method according to claim 6, characterized in that: The temperature of the flue gas produced by the heat source supply system is 1050 to 1150°C, and the oxygen content is 2 to 5%. In the suspension reactor, cryolite and calcium fluoride in the cathode carbon powder react fully with sodium carbonate. Cryolite and calcium fluoride are mainly converted into gaseous sodium fluoride salt, sodium fluoride. Some aluminum fluoride and carbon dioxide also enter the gas phase. The solid products are carbon powder and sodium aluminate.

10. The treatment method according to claim 6, characterized in that: The condensation and collection device cools the gas to below 200°C to promote the condensation and precipitation of fluorides.

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