Harmless fluorine removal method for electrolytic aluminum waste residues

Abstract

The invention discloses a harmless defluorination method for electrolytic aluminum waste residues, which belongs to the field of defluorination of electrolytic aluminum waste residues, and is characterized in that strong acid leaching is replaced by the coordinated treatment of turbulence breaking, ultrasonic activation and adsorption locking through the linkage coordination of parts such as a multistage reactor, so that the introduction of excessive salt is avoided, and the amount of process wastewater is effectively reduced; the NH4F aerosol can be recycled, the recycling efficiency is effectively improved, meanwhile, the NH4F aerosol can be reused as an industrial raw material, the resource utilization rate is greatly improved, meanwhile, all-phase trapping of fluorine is achieved, namely liquid-phase fluorine and gas-phase fluorine are locked and trapped through a multi-stage reactor, then solid-phase fluorine is locked and trapped through a curing reaction kettle, and therefore the recovery rate of the NH4F aerosol is increased. And efficient defluorination of the electrolytic aluminum waste residues is achieved.

Description

Technical Field

[0001] The present invention relates to the field of defluorination of electrolytic aluminum waste residue, and particularly to a harmless defluorination method for electrolytic aluminum waste residue. Background Art

[0002] Electrolytic aluminum waste residue refers to the waste generated during the electrolytic aluminum process of bauxite, which is mainly composed of various metal oxides, fluorides and other impurities, and is usually the ore residue that has not been reduced by molten aluminum during the electrolytic aluminum production process.

[0003] In view of the above problems, a method for recovering lithium from electrolytic aluminum solid waste materials (patent number: CN115872423A) is provided in a Chinese patent, which realizes the precise recovery of fluorine, aluminum and lithium in electrolytic aluminum solid waste materials through sulfuric acid-aluminum salt mixed leaching and two-stage fractional precipitation, and obtains high-value-added products such as cryolite, aluminum fluoride and lithium carbonate respectively;

[0004] However, in the actual use process of the above technical solution, due to the introduction of a large amount of acid and alkali in the front-end process, the salt content of the filtrate is too high, and too many crystals in the evaporation and concentration process easily cause blockage of the slurry pump, greatly affecting the production efficiency, and the tail liquid after crystallization and precipitation contains a high amount of fluorine, which is very difficult to treat. Summary of the Invention

[0005] The purpose of the present invention is to provide a harmless defluorination method for electrolytic aluminum waste residue to solve the technical defects proposed in the background art.

[0006] The purpose of the present invention can be achieved by the following technical solutions: A harmless defluorination method for electrolytic aluminum waste residue includes the following steps:

[0007] Step 1: Crushing treatment of the waste residue. The electrolytic aluminum waste residue is transported to a crushing and screening machine, and the pH of the waste residue is adjusted during the crushing process;

[0008] Step 2: Adjusting the slurry viscosity. Start the screw feeder to send the crushed waste residue into the slurry preparation tank, adjust the slurry viscosity, and transport it to a multi-stage reactor through a diaphragm pump;

[0009] Step 3: Chemical precipitation treatment. Adjust the slurry flow rate through a multi-stage reactor, induce crystal fragmentation, add a nano-calcium oxide suspension to generate a new precipitate to reduce the fluorine concentration, and add double alkali to the slurry to maintain the pH range of the slurry to promote coprecipitation and further reduce the fluorine concentration;

[0010] Step 4: Packing adsorption treatment. Adsorb the residual F through the honeycomb ceramic packing in the multi-stage reactor - to generate an Al-F complex to further reduce the fluorine concentration;

[0011] Step 5: Pressure filtration treatment. Heat the slurry using a curing reactor and add a binder, and at the same time, form it under the pressure of a filter press.

[0012] The multi-stage reactor used in the above-mentioned defluorination method consists of a tank filled with honeycomb ceramic fillers, a fixed pipe 1 and a fixed pipe 2 for transporting the slurry. The flow guide vanes provided in the fixed pipe 1 and the fixed pipe 2 are used to adjust the flow velocity of the slurry.

[0013] Preferably, both the fixed pipe 1 and the fixed pipe 2 are provided with a tapered section, a sudden expansion chamber and a variable diameter pipe;

[0014] The sudden expansion chamber is located between the tapered section and the variable diameter pipe. The tapered section of the fixed pipe 1 is fixedly connected to a diaphragm pump through a pipeline. The variable diameter pipe of the fixed pipe 1 is fixedly connected to the tapered section of the fixed pipe 2 through a pipeline. The variable diameter pipe of the fixed pipe 2 is fixedly connected to the tank through a pipeline.

[0015] Preferably, the inlet diameter of the tapered section of the fixed pipe 1 is 200 mm, the outlet diameter is 80 mm. The sudden expansion chamber of the fixed pipe 1 is hemispherical, with a diameter of 120 mm and a sudden expansion ratio of 2.25;

[0016] The inlet diameter of the tapered section of the fixed pipe 2 is 200 mm, the outlet diameter is 100 mm. The sudden expansion chamber of the fixed pipe 2 is a flat ellipse, with a major axis of 150 mm, a minor axis of 100 mm and a sudden expansion ratio of 1.5.

[0017] Preferably, the fixed pipe 1 is horizontally arranged, and the fixed pipe 2 is arranged obliquely downward. The inclination direction is from the fixed pipe 1 to the tank, and the inclination angle is 5°;

[0018] The connection between the fixed pipe 2 and the tank is tangentially arranged, and the inclination angle is 45°. Honeycomb ceramic fillers are fixedly installed on the inner wall of the tank. Flow grooves are provided on the honeycomb ceramic fillers, and the flow grooves are spiral.

[0019] Preferably, a fixing plate is fixedly installed at the bottom of the tank. A filler layer is fixedly installed on the fixing plate. An outlet pipe is fixedly installed at the bottom of the tank. The outlet pipe is located below the fixing plate. An inlet pipe is fixedly installed on the outer wall of the tank. The inlet pipes are evenly spaced on the filler layer.

[0020] Preferably, piezoelectric ceramic transducers are fixedly installed on the sudden expansion chambers of both the fixed pipe 1 and the fixed pipe 2. There are multiple piezoelectric ceramic transducers, and the multiple piezoelectric ceramic transducers are evenly spaced on the outer wall of the sudden expansion chamber. There are multiple flow guide vanes, and the multiple flow guide vanes are evenly spaced in the tapered section.

[0021] Preferably, one end of the flow guide vane is movably connected to the inner walls of the fixed pipe 1 and the fixed pipe 2 through a rotating shaft. A magnetic block is fixedly installed on the flow guide vane. Electromagnets are fixedly installed on the outer walls of the fixed pipe 1 and the fixed pipe 2, and the positions of the electromagnets are adapted to the magnetic blocks.

[0022] Preferably, a feeding pipe 1 is fixedly installed on the fixed pipe 1. The feeding pipe 1 is located at the tapered section of the fixed pipe 1. A feeding pipe 2 is fixedly installed on the fixed pipe 2. The feeding pipe 2 is located at the sudden expansion cavity of the fixed pipe 2. There are multiple feeding pipes 2, and the multiple feeding pipes 2 are evenly spaced on the outer wall of the sudden expansion cavity.

[0023] The beneficial effects of the present invention are as follows:

[0024] (1) The present invention uses components such as a multi-stage reactor in combination. In the multi-stage reactor, a combination of an asymmetric hyperbolic tapered section and a hemispherical sudden expansion cavity is mostly adopted, so as to make the waste residue slurry generate a three-dimensional spiral motion. On the one hand, the mixing efficiency of the medicament is effectively improved, and at the same time, by driving the spiral motion of the waste residue slurry, the blockage of the pipeline is avoided;

[0025] At the same time, piezoelectric ceramic transducers are arranged at equal intervals on the outer wall of the multi-stage reactor. Through the horn, the ultrasonic energy is focused on the center of the slurry vortex, so that the particle size of the fluoride crystal is reduced to 5-10 μm, effectively improving the precipitation speed, reducing the processing pressure of subsequent equipment, and further improving the removal efficiency of fluorine;

[0026] (2) The present invention also pre-treats the electrolytic aluminum waste residue through the combined use of components such as a crushing and screening machine and a slurry preparation tank. After that, through the gradient treatment process of the multi-stage reactor, the fluorine content in the slurry is effectively reduced. At the same time, NH3 gas is input into the multi-stage reactor to capture the fluorine in the slurry to generate NH4F aerosol. While effectively improving the recovery efficiency, it can also be reused as an industrial raw material. Moreover, the gas and the slurry are in countercurrent contact, so that NH3 and PAC form a gas-liquid microinterface reaction in the countercurrent flow field, effectively improving the fluorine removal efficiency and realizing the efficient defluorination of electrolytic aluminum waste residue. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The following further describes the present invention with reference to the drawings;

[0028] Figure 1 is the process schematic diagram of the present invention;

[0029] Figure 2 is the structural schematic diagram of the present invention;

[0030] Figure 3 is the structural schematic diagram of the multi-stage reactor in the present invention;

[0031] Figure 4 is the structural schematic diagram of the fixed pipe 1 and the fixed pipe 2 in the present invention;

[0032] Figure 5 is the structural schematic diagram of the sudden expansion cavity of the fixed pipe 1 in the present invention;

[0033] Figure 6It is a schematic structural diagram of the second fixed tube's sudden expansion cavity in the present invention;

[0034] Figure 7 It is a schematic structural diagram inside the first fixed tube and the second fixed tube in the present invention;

[0035] Figure 8 It is a schematic structural diagram inside the tank body in the present invention;

[0036] Figure 9 It is a schematic structural diagram of the honeycomb ceramic filler in the present invention.

[0037] Legend: 1. Slurry preparation tank; 101. Diaphragm pump; 2. Multi-stage reactor; 201. First fixed tube; 202. Second fixed tube; 203. Tank body; 204. Honeycomb ceramic filler; 205. Flow channel; 206. Fixed plate; 207. Filler layer; 208. Liquid outlet pipe; 209. Air inlet pipe; 210. Piezoelectric ceramic transducer; 211. Flow guide vane; 212. Electromagnet; 213. First feeding pipe; 214. Second feeding pipe. Specific implementation mode

[0038] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0039] Embodiment 1: Please refer to Figure 1 - Figure 8 As shown in the figure, this embodiment is a method for harmless defluorination of electrolytic aluminum waste residue, which is realized by relying on the multi-stage reactor 2 and includes the first fixed tube 201, the second fixed tube 202, and the tank body 203. The first fixed tube 201 and the second fixed tube 202 are both provided with a tapered section, a sudden expansion cavity, and a reduced-diameter pipe;

[0040] The sudden expansion cavity is located between the tapered section and the reduced-diameter pipe. The tapered section of the first fixed tube 201 is fixedly connected to the diaphragm pump 101 through a pipeline, the reduced-diameter pipe of the first fixed tube 201 is fixedly connected to the tapered section of the second fixed tube 202 through a pipeline, and the reduced-diameter pipe of the second fixed tube 202 is fixedly connected to the tank body 203 through a pipeline.

[0041] Among them, the inlet diameter of the tapered section of the first fixed tube 201 is 200 mm, the outlet diameter is 80 mm, the sudden expansion cavity of the first fixed tube 201 is hemispherical with a diameter of 120 mm, and the sudden expansion ratio is 2.25. The inlet diameter of the tapered section of the second fixed tube 202 is 200 mm, the outlet diameter is 100 mm, the sudden expansion cavity of the second fixed tube 202 is a flat ellipse with a major axis of 150 mm and a minor axis of 100 mm, and the sudden expansion ratio is 1.5.

[0042] Piezoelectric ceramic transducers 210 are fixedly installed on the sudden expansion cavities of the first fixed pipe 201 and the second fixed pipe 202. There are multiple piezoelectric ceramic transducers 210, and the multiple piezoelectric ceramic transducers 210 are evenly spaced on the outer wall of the sudden expansion cavity. A plurality of flow guide vanes 211 are movably installed inside the tapered section, and the plurality of flow guide vanes 211 are evenly spaced in the tapered section.

[0043] The first fixed pipe 201 is horizontally arranged, and the second fixed pipe 202 is arranged obliquely downward. The inclination direction is from the first fixed pipe 201 to the tank body 203, and the inclination angle is 5°. The connection between the second fixed pipe 202 and the tank body 203 is tangentially arranged, and the inclination angle is 45°. A honeycomb ceramic filler 204 is fixedly installed on the inner wall of the tank body 203. Flow channels 205 are formed on the honeycomb ceramic filler 204. The flow channels 205 are spiral. The main component of the honeycomb ceramic is cordierite or mullite. Its structural characteristics are: the pore diameter is 2 mm, allowing the slurry to pass through, while intercepting particles >50 μm, the wall thickness is 0.3 mm, the porosity is 85%, and the open pore rate >95%.

[0044] That is, the slurry enters the tank body 203 tangentially through the pipeline. Under the action of the flow channels 205, the slurry flows in a spiral shape, effectively increasing the contact time and contact area between the slurry and the honeycomb ceramic filler 204, and effectively improving the adsorption effect.

[0045] A fixing plate 206 is fixedly installed at the bottom of the tank body 203. A filler layer 207 is fixedly installed on the fixing plate 206. A liquid outlet pipe 208 is fixedly installed at the bottom of the tank body 203. The liquid outlet pipe 208 is located below the fixing plate 206. An air inlet pipe 209 is fixedly installed on the outer wall of the tank body 203. The air inlet pipes 209 are evenly spaced on the filler layer 207. During the process of the slurry being treated by the honeycomb ceramic filler 204, NH3 gas is conveyed into the tank body 203 through the air inlet pipe 209. Microbubbles with a diameter of 0.5 - 1 mm are formed in the honeycomb pores of the filler layer 207. During the rising process of the bubbles, F - is captured to generate NH4F aerosol, realizing the synergistic purification of liquid-phase fixation - gas-phase removal of fluorine by integrating the triple functions of adsorption, reaction, and gas capture.

[0046] At the same time, the pores of the filler layer 207 are backflushed by using NH3 gas, that is, impurities blocking the pores are flushed out by high-speed air flow, effectively avoiding blockage of the filler layer 207 and increasing the working time of the equipment.

[0047] One end of the guide plate 211 is movably connected to the inner wall of the fixed tube 1 201 and the fixed tube 2 202 through a rotating shaft. A magnetic block is fixedly installed on the guide plate 211, and an electromagnet 212 is fixedly installed on the outer wall of the fixed tube 1 201 and the fixed tube 2 202. The position of the electromagnet 212 is adapted to the magnetic block. That is, in actual use, the electromagnet 212 is energized to make it magnetic, thereby generating a repulsive force on the magnetic block, thereby pushing multiple guide plates 211 to rotate and deviate at the same time.

[0048] The guide vane 211 in the fixed tube 201 has an adjustable angle range of 0-15°. The slurry is guided to form a three-dimensional spiral flow through the deflection of the guide vane 211, and the flow velocity is increased from 1.2 m / s to 4.5 m / s by reducing the cross-sectional area of ​​the fluid. Strong turbulence is used to make the nano calcium oxide agent fully contact with the waste slag particles, shortening the reaction time. At the same time, the spiral flow field inhibits particle sedimentation to avoid blockage. At the same time, the guide vane 211 and the piezoelectric ceramic transducer 210 work together to effectively improve the crushing efficiency of the CaF2 crystal.

[0049] The specific linkage mode between the guide plate 211 and the piezoelectric ceramic transducer 210 is as follows:

[0050] Through the linkage formula , where P is the ultrasonic power in W, that is, when the guide vane angle θ increases from 0° to 15°, the ultrasonic power P increases linearly from 800W to 2000W, achieving precise matching of the flow field kinetic energy and the acoustic field energy.

[0051] Example: When θ=10°, At this time, the turbulence intensity and the cavitation effect reach the best coordinated state, that is, when the deflection of the guide vane 211 increases, the flow field shear force is enhanced, the cavitation bubble distribution is more uniform, and the CaF2 crystal crushing efficiency is improved. At this time, the ultrasonic energy is focused on the vortex center, and the cavitation energy density per unit volume reaches 12J / cm³.

[0052] The guide vane 211 in the fixed tube 202 has an adjustable angle range of 5-20°. The guide vane 211 reduces the slurry flow rate to 3.1 m / s, prolongs the reaction time to 12 s, and promotes the co-precipitation of CaF2 microcrystals and double alkali, effectively improving the fluorine removal rate. The guide vane 211 moves in an offset manner during adjustment to form a staggered vortex, further improving the slurry mixing efficiency.

[0053] A feeding pipe 213 is fixedly installed on the fixed pipe 201, and the feeding pipe 213 is located at the tapered section of the fixed pipe 201. A feeding pipe 214 is fixedly installed on the fixed pipe 202, and the feeding pipe 214 is located at the sudden expansion cavity of the fixed pipe 202. There are multiple feeding pipes 214, and the multiple feeding pipes 214 are evenly spaced on the outer wall of the sudden expansion cavity.

[0054] Among them, the feeding pipe 1 (213) is used to put the nano-calcium oxide suspension into the slurry. The particle size of CaO is 50 nm and the concentration is 10%, which is used to react with the dissolved F - to generate CaF2 precipitate. The feeding pipe 2 (214) is used to put double alkalis, namely NaOH and Na2CO3, into the slurry in the pipe 2 (202). The concentration is 20%, which is used to maintain the pH = 6.5 - 7.0 and optimize the precipitation conditions.

[0055] That is, in the multi-stage reactor 2, an asymmetric hyperbolic taper section and a hemispherical sudden expansion cavity are mostly used to make the waste residue slurry generate a three-dimensional spiral motion. On the one hand, the mixing efficiency of the effective agent is improved. At the same time, by driving the spiral motion of the waste residue slurry, the blockage of the pipeline is avoided;

[0056] At the same time, piezoelectric ceramic transducers 210 are arranged at equal intervals on the outer wall of the multi-stage reactor 2. Through the horn, the ultrasonic energy is focused on the center of the slurry vortex, so that the particle size of the fluoride crystals is reduced to 5 - 10 μm, the precipitation speed is increased by 3 times, the processing pressure of the subsequent equipment is reduced, and the removal efficiency of fluorine is effectively improved.

[0057] Example 2: Please refer to Figure 1 As shown in the figure, a method for harmless defluorination of electrolytic aluminum waste residue includes the following steps:

[0058] Step 1: Crushing treatment of the waste residue. The electrolytic aluminum waste residue with a moisture content < 5% is transported to a crushing and screening machine and crushed to less than 80 meshes by a jaw crusher roll and a ball mill. During the crushing process, 5% dilute sulfuric acid is sprayed to adjust the pH to 4.5 - 5.0;

[0059] Through the physical shear force of the jaw crusher roll and the ball mill, the crystal structure of the waste residue is destroyed, the specific surface area is increased, and at the same time, the encapsulated fluoride is exposed. During the process, 5% dilute sulfuric acid is sprayed to react with the metal fluorides (such as CaF2, Na3AlF6) in the waste residue to generate soluble fluoride ions (F - ), and sulfate precipitates.

[0060] That is, the encapsulated fluoride is dissociated, the availability of fluoride ions in the subsequent reaction is improved, and at the same time, traditional strong acid leaching is avoided, the acid consumption is reduced by 80%, and the salt formation is controlled from the source.

[0061] Step 2: Adjusting the slurry viscosity. Start the screw feeder to feed the crushed waste residue into the slurry preparation tank 1 at a solid-liquid ratio of 1:3, adjust the slurry viscosity to 300 - 500 mPa·s, and transport it to the multi-stage reactor 2 through the diaphragm pump 101;

[0062] Through the slurry preparation with a solid-liquid ratio of 1:3, the viscosity is reduced to 300 - 500 mPa·s (thixotropic fluid), ensuring the stability of pipeline transportation. At the same time, the pH = 4.5 - 5.0 is maintained to inhibit the re-precipitation of CaF2 and avoid the introduction of excessive acid.

[0063] This provides a homogenized reaction medium for subsequent multi-stage reactor 2 for stepwise defluorination, reduces the alkali consumption in the subsequent neutralization process, and effectively reduces the salt load.

[0064] Step 3: Chemical precipitation treatment. Adjust the slurry flow rate through multi-stage reactor 2, induce the CaF2 crystals to break to below 5 μm, add a nano-calcium oxide suspension to generate new CaF2 precipitates, and reduce the fluorine concentration from 8% to 2.5%.

[0065] In this process, the slurry enters fixed tube 1-201, induces a three-dimensional spiral flow through an asymmetric hyperbolic taper section, the slurry flow rate reaches 4.5 m / s, and at the same time, cavitation bubble collapse is generated by 28 kHz ultrasonic waves to break the CaF2 crystals to below 5 μm. Add a nano-calcium oxide (CaO, 50 nm) suspension, and react with F - to generate microcrystalline CaF2.

[0066] That is, fluorine removal is quickly completed, and the microcrystalline CaF2 serves as the crystal seed for the secondary reaction, reducing the subsequent chemical dosage.

[0067] At the same time, add NaOH / Na2CO3 double alkali to the slurry through multi-stage reactor 2 to maintain the pH range of the slurry at 6.5 - 7.0 to promote coprecipitation, and further reduce the fluorine concentration to 0.8%.

[0068] In this process, the slurry enters fixed tube 2-202, the outlet of the taper section expands to Φ100 mm, the flow rate drops to 3.1 m / s, and the reaction time is extended to 12 s. At the same time, first add Na2CO3 to precipitate excess Ca 2+ (scale prevention), and then switch to NaOH to adjust the pH = 6.5 - 7.0 to promote F - and residual Ca 2+ / Al 3+ coprecipitation.

[0069] That is, it avoids salt accumulation caused by a single alkali agent, further reduces the fluorine concentration, and reduces the salt generation amount.

[0070] Step 4: Packing adsorption treatment. Pass NH3 gas into multi-stage reactor 2 and contact it countercurrently with the slurry. At the same time, adsorb the residual F through honeycomb ceramic packing 204 - to generate an Al-F complex, and finally reduce the fluorine concentration to 0.15%.

[0071] In this process, the slurry enters tank 203, the slurry rotates downward tangentially from the top inlet (inclination angle 45°), contacts the NH3 gas introduced from the bottom countercurrently, forms a gas-liquid microinterface reaction, and at the same time, the honeycomb ceramic packing 204 locks the residual F through chemical adsorption - ;

[0072] That is, deep defluorination is achieved to solve the problem of high fluorine residue in the tail liquid of traditional processes. Meanwhile, NH4F aerosol is recovered to increase the resource utilization benefits.

[0073] Step Five: Pressure filtration treatment. The slurry after being treated by the multi-stage reactor 2 is transported to the solidification reaction kettle. Start the microwave module of the solidification reaction kettle, heat the slurry to 150°C and add sodium silicate binder. Meanwhile, the filter press forms at a pressure of 8 - 15 MPa.

[0074] The solidified body obtained through microwave crystallization and high-pressure filtration can be directly and safely buried. Among them, microwave crystallization refers to inducing the crystal form transformation of CaF2 to the α phase (thermodynamic stable state) through a 2.45 GHz microwave field, and high-pressure filtration refers to removing moisture at a pressure of 8 - 15 MPa. Embedded nano-Al2O3 seeds form an Al2O3 - SiO2 - CaF2 eutectic network with silicate. The unqualified slurry flows back to Step One through the reflux pipe for secondary treatment.

[0075] First, the electrolytic aluminum waste residue is pretreated. Then, through the gradient treatment process of the multi-stage reactor 2, the fluorine content in the slurry is effectively reduced. Meanwhile, NH3 gas is input into the multi-stage reactor 2 to capture the fluorine in the slurry to generate NH4F aerosol. While effectively improving the recovery efficiency, it can also be reused as an industrial raw material. Moreover, the gas and the slurry are in countercurrent contact, enabling the formation of a gas-liquid micro-interface reaction between NH3 and PAC in the countercurrent flow field, and the fluorine removal efficiency is increased by 40%, thus realizing the efficient defluorination of electrolytic aluminum waste residue.

[0076] Combining Example One and Example Two, it can be seen that through the linkage and cooperation of components such as the multi-stage reactor 2, the combined treatment of turbulent fragmentation - ultrasonic activation - adsorption locking is adopted to replace strong acid leaching, avoiding the introduction of excessive salts, effectively reducing the process wastewater volume, and realizing the recovery of NH4F aerosol. While effectively improving the recovery efficiency, it can also be reused as an industrial raw material, greatly improving the resource utilization rate. At the same time, the full-phase capture of fluorine is also realized, that is, the multi-stage reactor 2 locks and captures the liquid-phase and gas-phase fluorine, and then the solidification reaction kettle locks and captures the solid-phase fluorine to achieve the efficient defluorination of electrolytic aluminum waste residue.

[0077] The above is only an illustration of the structure of the present invention. Those skilled in the art of this technology make various modifications or supplements to the described specific embodiments or use similar methods for substitution. As long as they do not deviate from the structure of the invention or exceed the scope defined by this claim book, they should fall within the protection scope of the present invention.

Claims

1. A harmless defluorination method for electrolytic aluminum waste slag, characterized in that: The following steps are involved: Step 1: Waste slag crushing treatment, the electrolytic aluminum waste slag is transported to the crushing and screening machine, and the pH value of the waste slag is adjusted during the crushing process; Step 2: adjusting the viscosity of the slurry, starting the screw feeder to feed the crushed waste residue into the slurry preparation tank (1), adjusting the slurry viscosity, and transporting the slurry to the multi-stage reactor (2) via the diaphragm pump (101); Step 3: Chemical precipitation treatment, adjusting the slurry flow rate through the multi-stage reactor (2) and inducing crystal breakage, adding nano calcium oxide suspension to generate new precipitation to reduce the fluorine concentration, and adding double alkali to the slurry to maintain the slurry pH range to promote co-precipitation and reduce the fluorine concentration; Step 4: Filler adsorption treatment, the honeycomb ceramic filler in the multi-stage reactor (2) adsorbs the residual F - The Al-F complex is generated to reduce the fluorine concentration; Step 5: Filter pressing treatment, using a curing reactor to heat the slurry and add a binder, and using a filter press to press and shape; The multi-stage reactor (2) used in the above-mentioned defluorination method is composed of a tank body (203) filled with honeycomb ceramic filler and a fixed pipe (201) and a fixed pipe (202) for conveying slurry. The guide plates (211) arranged in the fixed pipe (201) and the fixed pipe (202) are used to adjust the flow rate of the slurry.

2. The harmless defluorination method for electrolytic aluminum waste slag according to claim 1, characterized in that: The fixed pipe 1 (201) and the fixed pipe 2 (202) are both provided with a tapered section, a sudden expansion cavity and a diameter reducing pipe; The sudden expansion cavity is located between the tapered section and the reducer, the tapered section of the fixed tube (201) is fixedly connected to the diaphragm pump (101) via a pipeline, the reducer of the fixed tube (201) is fixedly connected to the tapered section of the fixed tube (202) via a pipeline, and the reducer of the fixed tube (202) is fixedly connected to the tank body (203) via a pipeline.

3. The harmless defluorination method for electrolytic aluminum waste slag according to claim 2, characterized in that: The inlet diameter of the tapered section of the fixed tube 1 (201) is 200 mm, and the outlet diameter is 80 mm. The sudden expansion cavity of the fixed tube 1 (201) is hemispherical, with a diameter of 120 mm, and a sudden expansion ratio of 2.25; The inlet diameter of the tapered section of the second fixed pipe (202) is 200 mm, and the outlet diameter is 100 mm. The sudden expansion cavity of the second fixed pipe (202) is a flat ellipse with a major axis of 150 mm, a minor axis of 100 mm, and a sudden expansion ratio of 1.

5.

4. The harmless defluorination method for electrolytic aluminum waste slag according to claim 3, characterized in that: The fixed pipe 1 (201) is arranged horizontally, and the fixed pipe 2 (202) is arranged to be inclined downward, and the inclination direction is from the fixed pipe 1 (201) to the tank body (203), and the inclination angle is 5°; The connection between the second fixed pipe (202) and the tank body (203) is tangentially arranged with an inclination angle of 45°. A honeycomb ceramic filler (204) is fixedly installed on the inner wall of the tank body (203). A flow groove (205) is provided on the honeycomb ceramic filler (204). The flow groove (205) is spiral-shaped.

5. The harmless defluorination method for electrolytic aluminum waste slag according to claim 4, characterized in that: A fixing plate (206) is fixedly mounted on the bottom of the tank body (203), a packing layer (207) is fixedly mounted on the fixing plate (206), a liquid outlet pipe (208) is fixedly mounted on the bottom of the tank body (203), the liquid outlet pipe (208) is located below the fixing plate (206), and an air intake pipe (209) is fixedly mounted on the outer wall of the tank body (203), the air intake pipes (209) are evenly spaced on the packing layer (207).

6. The harmless defluorination method for electrolytic aluminum waste slag according to claim 2, characterized in that: A piezoelectric ceramic transducer (210) is fixedly mounted on the sudden expansion cavity of the fixed tube 1 (201) and the fixed tube 2 (202), a plurality of the piezoelectric ceramic transducers (210) are provided, and the plurality of the piezoelectric ceramic transducers (210) are evenly spaced and distributed on the outer wall of the sudden expansion cavity, and a plurality of the guide vanes (211) are provided, and the plurality of the guide vanes (211) are evenly spaced and distributed in the tapered section.

7. The harmless defluorination method for electrolytic aluminum waste slag according to claim 6, characterized in that: One end of the guide plate (211) is movably connected to the inner walls of the first fixed tube (201) and the second fixed tube (202) via a rotating shaft; a magnetic block is fixedly mounted on the guide plate (211); and an electromagnet (212) is fixedly mounted on the outer walls of the first fixed tube (201) and the second fixed tube (202); the position of the electromagnet (212) matches the magnetic block.

8. The harmless defluorination method for electrolytic aluminum waste slag according to claim 7, characterized in that: A feeding pipe 1 (213) is fixedly installed on the fixed pipe 1 (201), and the feeding pipe 1 (213) is located at the tapered section of the fixed pipe 1 (201). A feeding pipe 2 (214) is fixedly installed on the fixed pipe 2 (202), and the feeding pipe 2 (214) is located at the sudden expansion cavity of the fixed pipe 2 (202). A plurality of feeding pipes 2 (214) are provided, and the plurality of feeding pipes 2 (214) are evenly spaced and distributed on the outer wall of the sudden expansion cavity.

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