Method and device for deep separation of aluminum and nickel from high-aluminum waste catalyst

Abstract

This invention relates to the field of waste catalyst recycling, and discloses a method and apparatus for deep separation of aluminum and nickel from high-alumina waste catalysts. The apparatus includes a pretreatment unit, a roasting and activation unit, an acid leaching unit, a solid-liquid separation unit, a solvent extraction deep separation unit, a back-extraction and recovery unit, a product preparation unit, and an automatic control and environmental protection auxiliary unit. The pretreatment unit is characterized by the following features: along the material flow direction, a jaw crusher, a cone crusher, a ball mill, a vibrating screen, a silo, and a screw feeder are sequentially arranged to form a closed-loop grinding and screening system; the roasting and activation unit is equipped with a continuous rotary kiln, a burner, a temperature sensor, and a controller; deep separation of aluminum and nickel ions is achieved through pH adjustment and multi-stage countercurrent centrifugal extraction, while a reflux pipeline is provided to achieve material circulation, effectively improving the nickel and aluminum recovery rates, with a nickel recovery rate ≥98% and an aluminum recovery rate ≥97%, solving the problem of incomplete aluminum-nickel separation in existing technologies.

Description

Technical Field

[0001] This invention relates to the field of waste catalyst recycling technology, specifically to a method and apparatus for deep separation of aluminum and nickel from high-alumina waste catalysts. Background Technology

[0002] In the field of industrial catalysis, high-alumina waste catalysts are widely generated in processes such as petroleum refining and chemical synthesis. If these waste catalysts are discarded directly, it will not only waste valuable metal resources such as aluminum and nickel, but the heavy metals they contain will also pollute the soil and water bodies, which does not meet the national requirements for solid waste resource utilization and environmental protection emissions.

[0003] Existing separation devices suffer from problems such as low separation accuracy, low aluminum and nickel recovery rates, high energy consumption, and poor continuity. Moreover, most devices can only achieve coarse separation and cannot meet the recovery needs of high-purity aluminum and nickel products. They also have drawbacks such as high solvent loss and inadequate environmental treatment, making them difficult to adapt to the requirements of continuous industrial production. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method and apparatus for deep separation of aluminum and nickel from high-alumina waste catalysts, solving the problem that the apparatus can only achieve coarse separation and cannot meet the recycling needs of high-purity aluminum and nickel products.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a deep separation device for aluminum and nickel in high-alumina waste catalyst, comprising a pretreatment unit, a roasting and activation unit, an acid leaching unit, a solid-liquid separation unit, a solvent extraction deep separation unit, a back-extraction and recovery unit, a product preparation unit, and an automatic control and environmental protection auxiliary unit, characterized in that: the pretreatment unit is sequentially arranged with a jaw crusher, a cone crusher, a ball mill, a vibrating screen, a silo, and a screw feeder along the material flow direction, forming a closed-loop grinding and screening system; the roasting and activation unit is equipped with a continuous rotary kiln, a burner, a temperature sensor, and a controller; the acid leaching unit... The unit is equipped with an acid-resistant reaction vessel, a stirring device, a reflux condenser, an online pH monitoring probe, and a heating jacket; the solid-liquid separation unit is equipped with a thickener, a filtrate storage tank, a plate and frame filter press, and a variable frequency pump; the solvent extraction deep separation unit is equipped with an aqueous phase storage tank, an organic phase storage tank, a pH adjustment device, and a multi-stage countercurrent centrifugal extraction unit; the back-extraction recovery unit is equipped with a back-extraction reaction vessel, a back-extraction agent storage tank, and a variable frequency pump; the product preparation unit is equipped with a nickel-rich liquid treatment system and an aluminum-rich liquid treatment system; the automatic control and environmental protection auxiliary unit is equipped with a DCS controller, an alkali washing desulfurization tower, an acid mist absorption tower, a wastewater neutralization treatment pool, and a sludge filter press.

[0006] Preferably, the vibrating screen of the pretreatment unit, the filtrate storage tank of the solid-liquid separation unit, the organic phase storage tank and the aqueous phase storage tank of the solvent extraction deep separation unit are all equipped with variable frequency pumps for stable material transport. The multi-stage countercurrent centrifugal extraction unit consists of 2-4 stage extraction centrifuges, 1 stage washing centrifuge and 1-2 stage back-extraction centrifuges connected in series, with a drum speed of 8000-12000 r / min and an organic phase to aqueous phase volume ratio of 1:1-1:2.

[0007] Preferably, the acid-resistant reactor is made of stainless steel, lined with polytetrafluoroethylene, and has a heating jacket on the outer wall. The heating jacket is heated by steam or heat transfer oil to control the leaching temperature. The stirring device rotates at 200-300 r / min, and the pH online monitoring probe has a measurement accuracy of ±0.1 pH.

[0008] Preferably, the pretreatment unit is equipped with a permanent magnet magnetic separator between the cone crusher and the ball mill, and the continuous rotary kiln is a steel cylinder with a high-alumina refractory brick lining on its inner wall, an inclination angle of 3°-5°, and a rotation speed of 0.5-1 r / min.

[0009] Preferably, the nickel-rich liquid treatment system is sequentially connected to a neutralization and impurity removal tank, a vacuum evaporator, a cooling crystallizer, a centrifugal dehydrator, and a nickel sulfate storage silo. The centrifugal dehydrator is equipped with a reflux pipe and is connected to the neutralization and impurity removal tank. The aluminum-rich liquid treatment system is sequentially connected to a hydrolysis precipitation tank, a filter press, a washing tank, a mesh belt calcining furnace, and an alumina storage silo. The mesh belt calcining furnace is equipped with a temperature control device to control the calcination temperature within the range of 900-1100℃.

[0010] Preferably, the right end of the continuous rotary kiln is provided with a discharge sealing device to prevent material leakage and heat loss during the roasting process; the alkali washing desulfurization tower is a packed type and has the same structure as the acid mist absorption tower; the wastewater neutralization treatment tank is lined with an anti-corrosion layer; and the sludge filter press is a chamber plate and frame filter press.

[0011] Preferably, a device for deep separation of aluminum and nickel from high-alumina waste catalyst includes the following steps:

[0012] S1. Raw material pretreatment: The high-alumina waste catalyst is crushed, ground and screened in sequence to remove impurities and obtain qualified fine material, which is then transported to the roasting and activation unit.

[0013] S2. Calcination and activation: The fine material is fed into a continuous rotary kiln, and the temperature is controlled at 500-700℃. Calcination is carried out for 30-40 minutes to convert aluminum and nickel elements into easily leached oxides. The exhaust gas is treated and then discharged.

[0014] S3. Acid leaching: The activated material is fed into an acid-resistant reactor, 1.5-2 mol / L hydrochloric acid is added, the liquid-solid ratio is controlled at 5:1-8:1, the temperature is 80-95℃, and leaching is carried out for 60-90 minutes to obtain aluminum-nickel mixed leaching.

[0015] S4. Solid-liquid separation: The aluminum-nickel mixed leaching solution is subjected to thickening and plate and frame filtration to separate the solid residue from the aluminum-nickel mixed filtrate. The filtrate is then transported to the solvent extraction deep separation unit.

[0016] S5. Solvent extraction for deep separation: Adjust the pH of the aluminum-nickel mixed filtrate to 2.5-2.8, and perform multi-stage countercurrent extraction with the organic phase in proportion to separate the aluminum-rich liquid and the supported organic phase.

[0017] S6. Back-extraction and recovery: Dilute hydrochloric acid back-extraction agent is added to the supported organic phase to obtain nickel-rich solution and regenerated organic phase.

[0018] S7. Product preparation: High-purity alumina is prepared by hydrolysis precipitation, filtration, washing, and calcination of aluminum-rich liquid; nickel sulfate is prepared by neutralization and impurity removal, vacuum concentration, cooling crystallization, and centrifugal dehydration of nickel-rich liquid.

[0019] S8, automatic control and environmental protection assistance, uses DCS controller to monitor and regulate the process parameters of each unit in real time, and simultaneously treats roasting tail gas, acid mist, wastewater and sludge to ensure that emissions meet standards.

[0020] Preferably, in step S5, the extraction separation coefficient of the multi-stage countercurrent centrifugal extraction unit is ≥10⁴, the aluminum content in the separated nickel-rich solution is ≤0.1 g / L, and the nickel content in the aluminum-rich solution is ≤0.05 g / L; the organic phase consists of P₂O₄ and sulfonated kerosene, with P₂O₄ volume fraction of 20%-30% and sulfonated kerosene volume fraction of 70%-80%, and the extraction separation coefficient is ≥10⁴. 4 .

[0021] Preferably, in steps S6 and S7, the concentration of the stripping agent is 1.5-2 mol / L, the volume ratio of the stripping agent to the supported organic phase is 1:1-1:2, the stripping rate is ≥99%, the Al2O3 content in the high-purity alumina product is ≥99%, and the Ni content in the nickel sulfate product is ≥22%.

[0022] Preferably, in step S8, after the roasting tail gas is desulfurized by alkaline scrubbing, the SO2 emission concentration is ≤50mg / m³. 3 After treatment by the acid mist absorption tower, the HCl emission concentration is ≤10mg / m³. 3 The pH value of the wastewater is 6-9 after neutralization.

[0023] This invention provides a method and apparatus for deep separation of aluminum and nickel from high-alumina waste catalysts. It has the following beneficial effects:

[0024] 1. This invention employs a complete process of pretreatment-calcination activation-solvent extraction for deep separation, combined with a sulfonated kerosene organic phase system. Through pH adjustment and multi-stage countercurrent centrifugal extraction, it achieves deep separation of aluminum and nickel ions. At the same time, a reflux pipeline is set up to realize material circulation, effectively improving the recovery rate of nickel and aluminum, with a nickel recovery rate of ≥98% and an aluminum recovery rate of ≥97%, thus solving the problem of incomplete aluminum-nickel separation in the prior art.

[0025] 2. The present invention adopts a horizontal layout, with uniform spacing and standardized connection of each unit device. Through the DCS automated control system, key parameters such as temperature and pH are monitored in real time and automatically adjusted, reducing manual intervention and lowering the difficulty of operation. At the same time, the equipment layout is compact and the process is smooth, which can realize continuous production and meet the needs of industrial-scale application.

[0026] 3. This invention is equipped with a complete set of environmental protection auxiliary units. The roasting tail gas is purified by an alkaline washing desulfurization tower, and the acid mist is treated by an acid mist absorption tower before being discharged. The wastewater from each unit is collected into a neutralization treatment pond and reused or discharged after meeting the standards. The sludge is discharged after being treated by pressure filtration. There are no harmful substances discharged at will throughout the process, which meets the requirements of green production. At the same time, the organic phase can be recycled, reducing production costs. Attached Figure Description

[0027] Figure 1 This is a diagram illustrating the method steps of the present invention;

[0028] Figure 2 This is a flowchart illustrating the overall process flow of the present invention.

[0029] The components include: 1. Jaw crusher; 2. Cone crusher; 3. Ball mill; 4. Vibrating screen; 5. Hopper; 6. Screw feeder; 7. Continuous rotary kiln; 8. Discharge sealing device; 9. Burner; 10. Exhaust gas duct; 11. Temperature sensor; 12. Controller; 13. Acid-resistant reactor; 14. Stirring device; 15. Reflux condenser; 16. pH online monitoring probe; 17. Heating jacket; 18. Acid metering feed pump; 19. Thickener; 20. Filtrate storage tank; 21. Plate and frame filter press; 22. Organic phase storage tank; 23. Aqueous phase storage tank. 24. Multi-stage countercurrent centrifugal extraction unit; 25. pH adjustment device; 26. Flow meter; 27. Neutralization and impurity removal tank; 28. Back-extraction reactor; 29. ​​Back-extraction agent storage tank; 30. Hydrolysis precipitation tank; 31. Vacuum evaporator; 32. Cooling crystallizer; 33. Centrifugal dewatering machine; 34. Nickel sulfate storage silo; 35. Filter press; 36. Washing tank; 37. Mesh belt calcining furnace; 38. Alumina storage silo; 39. DCS controller; 40. Alkali washing desulfurization tower; 41. Acid mist absorption tower; 42. Wastewater neutralization treatment tank; 43. Sludge filter press. Detailed Implementation

[0030] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Please see the appendix Figure 1 and attached Figure 2 This invention provides a method and apparatus for deep separation of aluminum and nickel from high-alumina waste catalysts, comprising the following steps:

[0032] S1. Raw material pretreatment: The high-alumina waste catalyst is crushed, ground and screened in sequence to remove impurities and obtain qualified fine material, which is then transported to the roasting and activation unit.

[0033] Waste catalyst feedstock first enters jaw crusher 1 through the feed inlet. This equipment utilizes the squeezing action between the moving jaw plate and the fixed jaw plate to initially crush the lumpy material. By adjusting the discharge port gap below jaw crusher 1, the material is crushed to below 20-40mm. The initially crushed material is then conveyed to cone crusher 2 through a solid pipeline. Cone crusher 2 uses an eccentric shaft to drive the crushing wall to perform a gyratory motion within the jaw wall, performing full-circumferential layered crushing of the material. Compared to jaw crushers, cone crusher 2 produces more uniform and cubical output particles, effectively reducing the proportion of needle-like and flaky materials, with the output particle size controlled within the range of 5-10mm. This tiered crushing mode avoids equipment wear and over-crushing caused by excessively large single-stage crushing ratios.

[0034] The crushed material enters ball mill 3 through a pipeline for fine grinding. Ball mill 3 is filled with high-alumina ceramic balls or steel balls as grinding media. Through the impact, erosion, and grinding action driven by the rotation of the cylinder, the original macroscopic pore structure of the spent catalyst is destroyed, partially exposing the nickel components encased within the aluminum matrix. The ground product is then conveyed to vibrating screen 4 for physical classification. Vibrating screen 4 employs a multi-layer high-frequency vibration mode to ensure sufficient stratification of the material on the screen surface. Coarse particles that do not meet the process requirements are retained on the screen surface and re-pumped back to the feed inlet of ball mill 3 through the dotted-line return pipe. The qualified powder passing through the screen enters hopper 5.

[0035] The hopper 5 plays a crucial role in the system's process buffering, smoothing out intermittent fluctuations in the upstream crushing and grinding processes and ensuring the stability of continuous production in the downstream stages. The bottom of the hopper 5 is connected to the screw feeder 6. This feeder is driven by a variable frequency motor, and by adjusting the speed of the screw shaft, precise control of the material delivery rate is achieved. This avoids drastic temperature fluctuations within the kiln and incomplete activation caused by sudden changes in the feed rate.

[0036] S2. Calcination and activation: The fine material is fed into the continuous rotary kiln 7, and the temperature is controlled at 500-700℃. Calcination is carried out for 30-40 minutes to convert aluminum and nickel elements into easily leached oxides. The exhaust gas is treated and then discharged.

[0037] The pretreated fine powder material is fed into the feed end of the continuous rotary kiln 7 by a screw feeder 6 at a uniform speed. The kiln body is installed at an incline, with the inclination angle strictly set between 3° and 5°. This angle setting is coupled with the rotational speed of the kiln body to precisely control the axial movement rate of the material inside the kiln. Under the combined action of gravity and the centrifugal force of the kiln rotation, the material forms a uniform tumbling layer inside the kiln, ensuring sufficient convection and radiation heat transfer between the material and the hot flue gas. The discharge end of the kiln body is equipped with a discharge sealing device 8, which adopts a structure combining mechanical and flexible seals to effectively prevent external cold air from entering the kiln and diluting the hot field. At the same time, through the action of the variable frequency induced draft fan in the exhaust gas duct 10, the kiln is maintained in a slightly negative pressure state, which ensures the smooth discharge of combustion products and avoids the leakage of dust and high-temperature gases.

[0038] Operating at 500-700℃, the high-alumina waste catalyst undergoes physical adsorption and structural water removal at high temperatures, leading to microcracks and pores in the originally stable aluminum matrix. Under this temperature field, the active components in the catalyst are oxidized to nickel oxide in an oxidizing atmosphere; simultaneously, the bonds of components that originally formed a spinel structure with aluminum loosen upon heating, causing lattice distortion. This allows metal ions to be stripped from the tightly layered structure and transformed into active centers easily captured by acid. Locking the upper temperature limit at 700℃ effectively prevents the conversion of alumina to stable α-Al₂O₃, thus avoiding a decrease in leaching rate due to excessive densification of the material.

[0039] The high-temperature exhaust gas generated during the roasting process contains small amounts of sulfur dioxide and nitrogen oxides. The exhaust gas is drawn out through exhaust gas duct 10. During pipeline transmission, some heat can be used to preheat the feed screw at the front end, achieving energy recovery for the system. The exhaust gas ultimately extends vertically to the right, connecting to the alkaline scrubbing desulfurization tower 40 in the automatic control and environmental auxiliary unit. Through the neutralization reaction of the alkaline scrubbing liquid, acidic gases are removed, ensuring that the exhaust gas indicators before being discharged into the atmosphere meet mandatory environmental protection requirements.

[0040] S3. Acid leaching: The activated material is fed into acid-resistant reactor 13, 1.5-2 mol / L hydrochloric acid is added, the liquid-solid ratio is controlled at 5:1-8:1, the temperature is 80-95℃, and leaching is carried out for 60-90 minutes to obtain aluminum-nickel mixed leaching.

[0041] After calcination and activation, the powder is discharged through the discharge port of the discharge sealing device 8, and under the action of gravity and horizontal thrust, enters the top feed port of the acid-resistant reactor 13 through a wear-resistant pipe. The acid-resistant reactor 13 adopts a vertical cylindrical structure, and its lining material is selected from polytetrafluoroethylene, industrial ceramics, or high-silica acid-resistant glass to resist chemical corrosion in a high-temperature and strong acid environment. The acid metering pump 18 pumps the prepared acid solution into the reactor at a uniform rate according to the preset solid-liquid ratio and the real-time feedback from the pH online monitoring probe 16.

[0042] To eliminate solid-phase coating during the leaching process and overcome liquid film mass transfer resistance, the stirring device 14 consists of a top-mounted motor, a stirring shaft, and multi-stage stirring blades. The motor drives the stirring shaft, which in turn drives the blades to create a strong turbulent flow field within the vessel, ensuring that the fine powder material remains completely suspended in the acid solution and significantly increasing the effective solid-liquid contact area. By controlling the stirring speed, the material circulation rate within the vessel is increased, ensuring that the chemical reaction is kinetically controlled rather than diffusion-controlled, thereby shortening the time to reach reaction equilibrium.

[0043] The chemical equilibrium of the leaching reaction is highly sensitive to temperature. The heating jacket 17 is tightly wrapped around the outer wall of the reactor, and heat is provided by introducing saturated steam or high-temperature heat transfer oil. In this embodiment, the leaching temperature is controlled between 80-95°C. Within this temperature range, the activated Al₂O₃ reacts with H₂O... + The reaction rate constant increases exponentially; simultaneously, this temperature is below the boiling point of the acid, effectively suppressing large-scale solvent evaporation and maintaining the stability of the solubility in the reaction system. A proportional control valve is installed at the jacket inlet, and the central control system performs PID regulation based on the actual temperature measured by the thermocouple inside the reactor, ensuring temperature control accuracy within ±1°C.

[0044] The pH online monitoring probe 16 is installed inside a protective sleeve on the side wall of the reactor to capture real-time changes in the acidity of the reaction system. As the leaching reaction proceeds, the acid is continuously consumed, and the pH value tends to rise. When the pH value exceeds the preset reaction threshold, the DCS controller 39 automatically instructs the acid metering pump 18 to replenish the acid. When the pH value stabilizes within a set time and the rate of change is less than 0.05 / h, the leaching reaction is considered to have reached its endpoint. This determination method based on real-time electrochemical data effectively avoids reagent waste caused by over-leaching or excessive metal content in the tailings caused by under-leaching.

[0045] The vapors and acid mist generated during the reaction enter the reflux condenser 15 through the exhaust port at the top of the reactor. Circulating cooling water flows through the condenser, causing the acid-containing vapors to rapidly condense on the tube wall and return to the reactor in liquid form. This process not only achieves a self-closed circulation of the acid solution, reducing raw material consumption and alleviating the processing load on the terminal acid mist absorption tower 41, but also realizes the inherent environmental friendliness of the process.

[0046] S4. Solid-liquid separation: The aluminum-nickel mixed leaching solution is subjected to sedimentation in thickener 19 and plate and frame filter press to separate the solid residue from the aluminum-nickel mixed filtrate. The filtrate is then transported to the solvent extraction deep separation unit.

[0047] The leaching slurry is pumped through a corrosion-resistant pump and a horizontal solid-line pipe from the outlet at the bottom of the acid-resistant reactor 13 into the inlet of the thickener 19. The thickener 19 adopts a cylindrical conical bottom structure. After the slurry enters the machine, the flow velocity decreases rapidly due to the sudden expansion of the flow cross-section. Under the action of gravity, the denser insoluble residues settle downwards to form concentrated underflow. An annular overflow trough is provided above the machine, and the clarified supernatant is temporarily stored in the filtrate storage tank 20 by gravity or pumping. A slowly rotating scraper is provided at the bottom of the thickener 19 to push the settled slurry towards the central discharge port, ensuring that the underflow mass fraction is maintained at 30%-45%, reducing the liquid load for subsequent pressure filtration.

[0048] The high-solids-content bottom stream discharged from thickener 19 enters the feed end of plate and frame filter press 3521 through a solid-line pipe that flows vertically downwards and then horizontally to the right. Plate and frame filter press 3521 utilizes the static pressure generated by the feed pump as the driving force. Under pressure, the material passes through the filter cloth; solid particles are trapped in the filter chamber to form a filter cake, while the liquid passes through the filter cloth into the filtrate channel. Compared to gravity separation, pressure filtration effectively removes micron-sized suspended impurities, ensuring that the turbidity of the filtrate is minimized. After the filter cake forms, the system can switch to washing mode, introducing a small amount of deionized water through the washing port of filter press 35 to squeeze and wash the filter cake. This step displaces the residual aluminum and nickel-rich leachate in the filter cake pores, allowing the washing liquid to flow into the main filtrate stream, thereby improving the overall metal recovery rate of the system. After filtration is completed, the plates and frames automatically open, and the relatively dry filter cake is discharged from the filter residue outlet below. The downward black arrows marked here indicate that the filter residue can be discharged externally and used as ceramic raw materials or disposed of in a secondary, harmless landfill.

[0049] The filtrate storage tank 20 serves as a buffer hub between the solid-liquid separation unit and the core extraction unit, balancing the liquid level and homogenizing the components. The top of the tank simultaneously receives overflow from the thickener 19 and filtrate from the plate and frame filter press 3521, achieving complete material collection. The interior of the tank is also made of acid-resistant material, utilizing volumetric effect to achieve secondary natural settling of fine dust. A variable frequency pump is installed at the tank outlet. This pump is controlled by the DCS controller 39, dynamically adjusting the pumping flow rate and pressure based on the real-time load of the next unit's centrifugal extraction unit.

[0050] By combining "concentration + pressure filtration", the suspended solids content in the filtrate that finally enters the storage tank is controlled to be below 10mg / L, preventing solid impurities from entering the multi-stage countercurrent centrifugal extraction unit and causing wear on the high-speed drum or clogging of the precision channels.

[0051] The buffering adjustment of the storage tank eliminates the uneven ion concentration caused by fluctuations in the front-end acid leaching reaction, providing a stable material basis for the precise operation of the pH adjustment device 25 in step S5.

[0052] S5. Solvent extraction for deep separation: Adjust the pH of the aluminum-nickel mixed filtrate to 2.5-2.8, and perform multi-stage countercurrent extraction with the organic phase in proportion to separate the aluminum-rich liquid and the supported organic phase.

[0053] This embodiment employs a cation exchange extraction system, in which the organic phase is prepared by mixing the extractant P204 (di-2-ethylhexyl phosphoric acid) and the diluent sulfonated kerosene at a volume ratio of 15%-30%. During the contact between the aqueous and organic phases, P204 exists in dimer form. It undergoes the following exchange reaction with metal ions in the aqueous phase:

[0054]

[0055] in, This represents nickel or aluminum ions in the aqueous phase. Because the partition coefficient of nickel ions into the organic phase is strongly correlated with pH in this system, the chemical equilibrium can be induced to shift towards the formation of the supported organic phase by precisely controlling the hydrogen ion concentration.

[0056] The mixed filtrate first enters the aqueous phase storage tank 23, which is an important stage for adjusting the physical properties before extraction. The pH adjustment device 25 adds alkaline solution dropwise to the aqueous phase in real time to precisely stabilize the pH value within the range of 2.5-2.8. The aqueous phase storage tank 23 and the organic phase storage tank 22 are respectively connected to the centrifuge unit through dedicated variable frequency pumps.

[0057] The core equipment of this unit is the multi-stage countercurrent centrifugal extraction unit 24. Driven by a motor, the centrifuge drum rotates at speeds of up to 8000-12000 r / min. Under the powerful centrifugal force, the oil and water phases are sheared into micron-sized droplets, increasing the contact area between the two phases by several orders of magnitude compared to traditional stirred towers. The extremely high rotational speed not only achieves instantaneous mixing but also ensures phase separation within 10-30 seconds. Flow meters 26 are installed on all key connecting pipes to monitor the instantaneous flow rates of the aqueous and organic phases in real time, preventing phase equilibrium shifts caused by pump speed fluctuations.

[0058] To achieve extremely high yield and purity, the unit employs a fully counter-current flow design: a mixed aqueous phase containing aluminum and nickel enters from the aqueous phase inlet of the last stage centrifuge, flowing to the left in each stage and undergoing multiple collisions and exchanges with the organic phase. During this process, the nickel ion concentration in the aqueous phase decreases progressively. The pure organic phase enters from the organic phase inlet of the first stage centrifuge, flowing to the right in each stage. As it flows towards the end, the nickel concentration in the organic phase gradually becomes saturated.

[0059] The residue after multi-stage extraction is discharged from the heavy phase outlet. At this point, most of the nickel in the solution has been extracted, forming an aluminum-rich solution, which is then transported to the product preparation unit. The organic phase carrying nickel ions forms a loaded organic phase, which is discharged from the light phase outlet and enters the subsequent washing and back-extraction processes.

[0060] To further purify and recover the solvent, the loaded organic phase enters a washing centrifuge and is washed countercurrently with a small amount of pure water or dilute acid. The resulting heavy phase reflux liquid is returned to the aqueous phase storage tank 23 via the dotted-line pipe for re-extraction, ensuring zero metal loss. The purified loaded organic phase then enters a back-extraction centrifuge. High-concentration acid from the back-extraction recovery unit is used as the back-extraction agent, forcing nickel ions to return from the organic phase to the aqueous phase according to the principle of chemical equilibrium shift, forming a nickel-rich solution. The lean organic phase after back-extraction is returned to the top organic phase storage tank 22 via the dotted-line reflux pipe for recycling.

[0061] S6. Back-extraction and recovery: Dilute hydrochloric acid back-extraction agent is added to the supported organic phase to obtain nickel-rich solution and regenerated organic phase;

[0062] The efficiency of the back-extraction process depends on the affinity competition between the back-extraction agent and metal ions. In this embodiment, dilute hydrochloric acid is used as the back-extraction agent, and the back-extraction agent storage tank 29 contains dilute hydrochloric acid with a concentration of 1.5-2 mol / L. This concentration range is determined based on the principle of chemical equilibrium shift: high concentrations of H+... + It can instantly replace the metal cations bound to P204 molecules in the supported organic phase, causing them to undergo the following reverse reaction:

[0063]

[0064] Selecting this concentration range for back-extraction ensures that metal ions achieve a back-extraction rate close to 100%, while minimizing the hydrolysis loss of organic phase molecules and extending their service life.

[0065] The loaded organic phase enters the back-extraction centrifuge from the extraction unit, where it comes into countercurrent contact with the back-extraction agent from the storage tank. In the high-shear flow field of the back-extraction centrifuge, the acid solution and the loaded organic phase undergo proton exchange on a microsecond scale. The heavy phase liquid after back-extraction collects and enters back-extraction reactor 28. Back-extraction reactor 28 adopts a vertical cylindrical acid-resistant structure with a feed inlet at the top center. This reactor not only acts as a material buffer but also ensures, through secondary mixing, that trace amounts of organic phase in the back-extraction liquid can further float naturally and be intercepted, thereby improving the chemical purity of the product in the subsequent S7 step.

[0066] This implementation method utilizes H + The concentration effect of ions achieves an equilibrium shift. In the solvent extraction unit, metal ions combine with organic matter to release H₂. +In this unit, by introducing a high concentration of hydrogen ions, the reaction is promoted to proceed in the reverse direction, towards the formation of hydrated metal ions:

[0067]

[0068] in, The main component is the extracted nickel ions. By maintaining extremely high acidity, the reaction can achieve a back-extraction efficiency of over 99.5%, ensuring that the loaded metal in the organic phase is completely stripped away.

[0069] The stripping agent storage tank 29 is used to store the prepared dilute hydrochloric acid. In this embodiment, a dilute hydrochloric acid concentration of 1.5-2 mol / L is selected as the stripping agent. This concentration range not only provides sufficient proton strength but also avoids oxidative degradation of the organic phase molecular framework due to excessive acidity. The bottom of the storage tank is connected to the stripping system via a variable frequency pump. The DCS system dynamically adjusts the speed of the stripping agent feed pump based on the real-time flow rate of the loaded organic phase fed back by the flow meter 26. This "proportion-following" control logic ensures that the proportion is always within the optimal range during the stripping process, thereby obtaining a nickel solution with a high enrichment factor.

[0070] The back-extraction process is completed in a back-extraction centrifuge connected in series at the end of the unit. The loaded organic phase and the back-extraction agent undergo violent collisions in the high-speed rotating drum of the centrifuge, resulting in high concentrations of H₂. + The metal ions on the functional groups of the organic phase are instantaneously replaced. Since the back-extraction reaction is usually faster than the extraction reaction, the rapid separation effect of the centrifugal force field effectively prevents the stripped ions from undergoing secondary emulsification. The back-extracted heavy phase is discharged from the heavy phase outlet of the centrifuge, forming a nickel-rich solution, which then enters the back-extraction reactor 28 through a vertically downward pipe.

[0071] The back-extraction reactor 28 serves as a deep processing and buffer device for the system, performing flash degassing and further phase clarification on the discharged nickel-rich liquid. The reactor is equipped with temperature control compensation logic to maintain a micro-thermal environment, which is beneficial for the further separation of trace amounts of entrained organic phases.

[0072] After processing in this unit, it returns to step S5 to participate in the next extraction cycle; the liquid containing high concentration of nickel chloride is discharged from the bottom of the back-extraction reactor 28 and transported to the product preparation unit for crystallization.

[0073] S7. Product preparation: High-purity alumina is prepared by hydrolysis precipitation, filtration, washing, and calcination of aluminum-rich liquid; nickel sulfate is prepared by neutralization and impurity removal, vacuum concentration, cooling crystallization, and centrifugal dehydration of nickel-rich liquid.

[0074] The nickel-rich solution first enters the neutralization and impurity removal tank 27. A trace amount of conditioning agent is added to the tank to further precipitate any remaining trace impurity ions and adjust the supersaturation level of the solution. This step ensures that the final product achieves a Ni content of ≥22%. The purified solution is then pumped into the vacuum evaporator 31. Vacuum evaporation utilizes the principle of lowering the boiling point of the solution by reducing ambient pressure, allowing water to vaporize rapidly at a lower temperature. This avoids thermal degradation of nickel sulfate at high temperatures or premature precipitation of fine crystal nuclei, ensuring the solution reaches a stable supersaturated state. The concentrated, hot-saturated solution enters the cooling crystallizer 32. The crystal slurry enters the centrifugal dehydrator 33, where solid-liquid separation is achieved under strong centrifugal force. The dehydrated mother liquor is returned to the neutralization and impurity removal tank 27 for recirculation through the dotted-line return pipe. After drying, the wet crystals are sent to the nickel sulfate storage silo 34. The resulting nickel sulfate product meets the high standard requirement of Ni ≥22%.

[0075] The aluminum-rich liquid enters the hydrolysis sedimentation tank 30. By controlling the hydrolysis temperature and pH value, aluminum ions undergo a hydrolysis reaction to generate aluminum hydroxide colloid.

[0076]

[0077] After the precipitated slurry is formed into a cake by the filter press 35, it enters the washing tank 36 for multiple replacement washings. This step, through multiple "slurrying-filtration" cycles, thoroughly removes chloride or sulfate ions entrained in the filter cake, which is crucial for ensuring the purity of alumina. The washed alumina filter cake is then fed into a mesh belt calcining furnace 37. The furnace is equipped with multiple temperature control zones, with the operating temperature strictly controlled between 900-1100℃. At this high temperature, the alumina undergoes dehydration and crystal transformation. The mesh belt structure ensures uniform heating of the material in the high-temperature zone, avoiding localized over- or under-burning, and ensuring the activity and whiteness of the product. The calcined product is cooled and then sent to the alumina storage silo 38. The final high-purity Al2O3 produced has a purity ≥99% and can be widely used in ceramics, abrasives, or catalyst carriers.

[0078] S8, Automatic Control and Environmental Protection Auxiliary: The DCS controller 39 monitors and controls the process parameters of each unit in real time, and simultaneously treats roasting tail gas, acid mist, wastewater and sludge to ensure that emissions meet standards.

[0079] The controller 12 connects the sensors and actuators distributed in each unit via short-circuit electrical signals. It receives thermal signals from the temperature sensor 11 of the continuous rotary kiln 7, the heating jacket 17 of the acid-resistant reactor 13, and the temperature control device of the mesh belt calcining furnace 37. Using a PID algorithm, it adjusts the air-fuel ratio and electric heating power of the burner 9 in real time to control temperature fluctuations within ±5°C. It also receives data from the online pH monitoring probe 16 and the pH adjustment device 25, dynamically controlling the acid metering pump 18 and the alkali dripping valve to ensure the acid-base environment during leaching and extraction is within the optimal kinetic window.

[0080] Based on the physical characteristics of the waste gas generated in different processes, the system adopts a design of classified treatment and centralized emission. High-temperature tail gas from the continuous rotary kiln 7 is sent to the alkaline washing desulfurization tower 40 via tail gas duct 10. The tower is equipped with multi-layered, multi-faceted hollow spherical packing, and the top is sprayed with an alkaline washing solution prepared with sodium hydroxide. SO2 and dust in the tail gas fully contact the alkaline solution on the packing surface and undergo a neutralization reaction. The purified tail gas is discharged by the top fan, ensuring that the emission concentration meets the national industrial furnace and kiln air pollutant emission standards. The acid mist absorption tower 41 undertakes dual purification tasks. It receives non-condensable acidic gas from the acid-resistant reactor 13 after condensation by the reflux condenser 15. It also receives volatile acid mist generated from the back-extraction reactor 28. The tower uses a two-stage counter-current spray system, utilizing the principle of chemical absorption to convert HCl or H2SO4 vapor into the corresponding inorganic salt solution. After the concentration increases, the solution is introduced into the front-end acid leaching unit as supplementary acid water, realizing the resource utilization of the waste gas.

[0081] All equipment flushing water, condensate, and process wastewater generated by the entire unit are collected in a wastewater neutralization treatment tank 42. In the tank, a composite oil remover and heavy metal precipitant are added to convert residual trace metal ions in the wastewater into stable chelated precipitates. The treated clarified liquid is reused in the washing tank 36 or used as makeup water for circulating cooling water, significantly reducing the consumption of fresh water per ton. The settled sludge at the bottom of the treatment tank is pumped into a sludge filter press 43. After high-pressure dewatering, dry sludge cakes are formed, with a moisture content reduced to below 40%, which can be used as raw material for brick factories or sent to a dedicated solid waste treatment station for harmless disposal.

[0082] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A device for deep separation of aluminum and nickel from high-alumina waste catalyst, comprising a pretreatment unit, a roasting and activation unit, an acid leaching unit, a solid-liquid separation unit, a solvent extraction deep separation unit, a back-extraction and recovery unit, a product preparation unit, and an automatic control and environmental protection auxiliary unit, characterized in that: The pretreatment unit is arranged sequentially along the material flow direction with a jaw crusher (1), a cone crusher (2), a ball mill (3), a vibrating screen (4), a silo (5), and a screw feeder (6), forming a closed-loop grinding and screening system; the roasting and activation unit is equipped with a continuous rotary kiln (7), a burner (9), a temperature sensor (11), and a controller (12); the acid leaching unit is equipped with an acid-resistant reactor (13), a stirring device (14), a reflux condenser (15), a pH online monitoring probe (16), and a heating jacket (17); the solid-liquid separation unit is equipped with a thickener (19), a filtrate storage tank (10), a condensate storage tank (11), a condensate storage tank (12), a condensate storage tank (13), a condensate storage tank (14), a condensate storage tank (15), a condensate storage tank (16), a condensate storage tank (17), a condensate storage tank (18), a condensate storage tank (19), a condensate storage tank (12 ... 20) Plate and frame filter press (21) and variable frequency pump; The solvent extraction deep separation unit is equipped with an aqueous phase storage tank (23), an organic phase storage tank (22), a pH adjustment device (25) and a multi-stage countercurrent centrifugal extraction unit (24); The back-extraction recovery unit is equipped with a back-extraction reactor (28), a back-extraction agent storage tank (29) and a variable frequency pump; The product preparation unit is equipped with a nickel-rich liquid treatment system and an aluminum-rich liquid treatment system; The automatic control and environmental protection auxiliary unit is equipped with a DCS controller (39), an alkaline washing desulfurization tower (40), an acid mist absorption tower (41), a wastewater neutralization treatment pool (42) and a sludge filter press (43).

2. The device for deep separation of aluminum and nickel from high-alumina waste catalyst according to claim 1, characterized in that: The pretreatment unit's vibrating screen (4), the solid-liquid separation unit's filtrate storage tank (20), the solvent extraction deep separation unit's organic phase storage tank (22) and aqueous phase storage tank (23) are all equipped with variable frequency pumps for stable material transport. The multi-stage countercurrent centrifugal extraction unit (24) consists of 2-4 stage extraction centrifuges, 1 stage washing centrifuges, and 1-2 stage back-extraction centrifuges connected in series. The drum speed is 8000-12000 r / min, and the volume ratio of organic phase to aqueous phase is 1:1-1:

2.

3. The device for deep separation of aluminum and nickel from high-alumina waste catalyst according to claim 1, characterized in that: The acid-resistant reactor (13) is made of stainless steel, with a polytetrafluoroethylene lining and a heating jacket (17) on the outer wall. The heating jacket (17) is heated by steam or heat transfer oil to control the leaching temperature. The stirring device (14) has a rotation speed of 200-300 r / min. The pH online monitoring probe (16) has a measurement accuracy of ±0.1 pH.

4. The device for deep separation of aluminum and nickel from high-alumina waste catalyst according to claim 1, characterized in that: The pretreatment unit is equipped with a permanent magnet magnetic separator between the cone crusher (2) and the ball mill (3). The continuous rotary kiln (7) is a steel cylinder with a high-alumina refractory brick lining on its inner wall. The tilt angle is 3°-5° and the rotation speed is 0.5-1r / min.

5. The device for deep separation of aluminum and nickel from high-alumina waste catalyst according to claim 1, characterized in that: The nickel-rich liquid treatment system is sequentially connected to a neutralization and impurity removal tank (27), a vacuum evaporator (31), a cooling crystallizer (32), a centrifugal dehydrator (33), and a nickel sulfate storage silo (34). The centrifugal dehydrator (33) is equipped with a reflux pipe and is connected to the neutralization and impurity removal tank (27). The aluminum-rich liquid treatment system is sequentially connected to a hydrolysis precipitation tank (30), a filter press (35), a washing tank (36), a mesh belt calcining furnace (37), and an alumina storage silo (38). The mesh belt calcining furnace (37) is equipped with a temperature control device to control the calcination temperature within the range of 900-1100℃.

6. The device for deep separation of aluminum and nickel from high-alumina waste catalyst according to claim 1, characterized in that: The continuous rotary kiln (7) is equipped with a discharge sealing device (8) at the right end to prevent material leakage and heat loss during the roasting process. The alkaline washing desulfurization tower (40) is a packed type and has the same structure as the acid mist absorption tower (41). The wastewater neutralization treatment pool (42) is lined with an anti-corrosion layer. The sludge filter press (43) is a box-type plate and frame filter press (21).

7. A method for deep separation of aluminum and nickel from high-alumina waste catalyst, comprising a device for deep separation of aluminum and nickel from high-alumina waste catalyst according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Raw material pretreatment: The high-alumina waste catalyst is crushed, ground and screened in sequence to remove impurities and obtain qualified fine material, which is then transported to the roasting and activation unit. S2. Calcination and activation: The fine material is fed into a continuous rotary kiln (7), the temperature is controlled at 500-700℃, and the material is calcined for 30-40 minutes to convert aluminum and nickel elements into easily leached oxides. The exhaust gas is treated and then discharged. S3, acid leaching: the activated material is sent into an acid-resistant reactor (13), 1.5-2 mol / L hydrochloric acid is added, the liquid-solid ratio is controlled at 5:1-8:1, the temperature is 80-95℃, and the leaching is carried out for 60-90 minutes to obtain aluminum-nickel mixed leaching. S4. Solid-liquid separation: The aluminum-nickel mixed leaching solution is subjected to sedimentation in a thickener (19) and plate and frame filter press to separate the solid residue from the aluminum-nickel mixed filtrate. The filtrate is then transported to the solvent extraction deep separation unit. S5. Solvent extraction for deep separation: Adjust the pH of the aluminum-nickel mixed filtrate to 2.5-2.8, and perform multi-stage countercurrent extraction with the organic phase in proportion to separate the aluminum-rich liquid and the supported organic phase. S6. Back-extraction and recovery: Dilute hydrochloric acid back-extraction agent is added to the supported organic phase to obtain nickel-rich solution and regenerated organic phase; S7. Product preparation: High-purity alumina is prepared by hydrolysis precipitation, filtration, washing, and calcination of aluminum-rich liquid. Nickel sulfate is prepared by neutralizing and removing impurities from nickel-rich liquid, concentrating under reduced pressure, cooling and crystallizing, and centrifuging to dehydrate. S8. Automatic control and environmental protection assistance: The process parameters of each unit are monitored and controlled in real time through the DCS controller (39), and the roasting tail gas, acid mist, wastewater and sludge are processed simultaneously to ensure that the emission meets the standards.

8. The method for deep separation of aluminum and nickel from high-alumina waste catalyst according to claim 7, characterized in that: In step S5, the extraction separation factor of the multistage countercurrent centrifugal extractor set (24) is ≥104, the aluminum content in the nickel-rich liquid after separation is ≤0.1 g / L, the nickel content in the aluminum-rich liquid is ≤0.05 g / L; the organic phase is composed of P204 and sulfonated kerosene, the volume fraction of P204 is 20%-30%, the volume fraction of sulfonated kerosene is 70%-80%, and the extraction separation factor is ≥10 4 .

9. The method for deep separation of aluminum and nickel from high-alumina waste catalyst according to claim 7, characterized in that: In steps S6 and S7, the concentration of the stripping agent is 1.5-2 mol / L, the volume ratio of the stripping agent to the supported organic phase is 1:1-1:2, the stripping rate is ≥99%, the Al2O3 content in the high-purity alumina product is ≥99%, and the Ni content in the nickel sulfate product is ≥22%.

10. The method for deep separation of aluminum and nickel from high-alumina waste catalyst according to claim 7, characterized in that: In step S8, after alkaline scrubbing and desulfurization, the SO2 emission concentration of the roasting tail gas is ≤50mg / m³. 3 After the acid mist is treated by the acid mist absorption tower (41), the HCl emission concentration is ≤10mg / m³. 3 The pH value of the wastewater is 6-9 after neutralization.

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