A method for comprehensive treatment of ternary precursor synthesis mother liquor and nickel-iron mother liquor

Abstract

The application provides a comprehensive treatment method of ternary precursor synthesis mother liquor and nickel-iron mother liquor, and the comprehensive treatment method comprises the following steps: (1) after solid-liquid separation of the nickel-iron mother liquor, diffusion dialysis treatment is carried out on the obtained nickel-iron filtrate to obtain residual acid and metal liquid, heavy metal removal and concentration treatment are carried out on the residual acid to obtain concentrated acid; (2) acidification and heavy metal removal treatment are carried out on the ternary precursor synthesis mother liquor by using the concentrated acid to obtain acidification liquid and carbon dioxide, solid-liquid separation is carried out on the acidification liquid to obtain acidification filtrate, secondary heavy metal removal treatment is carried out on the acidification filtrate to obtain secondary heavy metal removal liquid; (3) after adjusting the pH of the secondary heavy metal removal liquid, ammonia removal treatment is carried out on the secondary heavy metal removal liquid to obtain ammonia removal liquid and carbon ammonium liquid, double displacement electrodialysis treatment is carried out on the ammonia removal liquid and the carbon ammonium liquid to obtain light brine, light ammonium liquid, composite ammonium liquid and soda lye. The comprehensive treatment of the ternary precursor synthesis mother liquor and the nickel-iron mother liquor in the application produces composite ammonium salt and soda lye, and realizes resource recycling.

Description

Technical Field

[0001] This invention belongs to the field of resource recycling technology and relates to a comprehensive treatment method for ternary precursor synthesis mother liquor and nickel-iron mother liquor. Background Technology

[0002] In recent years, power lithium batteries using ternary materials as cathode materials have gradually occupied an increasingly important position in the power battery industry due to their important advantages such as high capacity, high energy density, good cycle stability, and moderate cost.

[0003] Currently, industrially used ternary cathode materials are generally produced by calcining lithium with hydroxides of Ni, Co, and Mn as precursors. The mainstream process for generating ternary material precursors is co-precipitation. This involves preparing a solution of mixed metal ions at a certain concentration, using NaOH as a precipitant and ammonia as a complexing agent, and adding them in parallel. After solid-liquid separation, the resulting slurry yields the ternary precursor material as a solid, while the filtrate is a sulfate solution containing ammonium and sodium. This solution also contains small amounts of heavy metal ions such as nickel, cobalt, and manganese. Therefore, effective resource recovery treatment of this ternary wastewater is necessary.

[0004] Iron-containing molten metal is used to synthesize ferric phosphate. The filtrate from the synthesized slurry after solid-liquid separation is called nickel-iron mother liquor. Its main component is a sulfate solution containing nickel and iron. This solution also contains a large amount of acid that is not fully utilized. At present, the main method for treating this type of high-acid liquid containing heavy metals is to recover the acid resources.

[0005] CN112010479A discloses a treatment process for ternary precursor wastewater, specifically: stripping the mother liquor generated during the preparation of the ternary precursor to obtain sodium sulfate; treating the washing water generated during the preparation of the ternary precursor with a multi-stage reverse osmosis membrane, and combining the concentrate generated in the multi-stage reverse osmosis membrane treatment with the mother liquor for further treatment; and reusing the dialysis liquid generated in the multi-stage reverse osmosis membrane treatment for production, thereby realizing the recycling treatment of ternary precursor wastewater.

[0006] CN109256532A discloses a method for comprehensive utilization of mother liquor in the synthesis process of ternary cathode material precursor for lithium-ion batteries, comprising the following steps: The ternary precursor mother liquor is fed from top to bottom into a stripping tower deammoniation system and a distillation tower for deammoniation, with the residence time for deammoniation per unit volume of mother liquor controlled at 0.5-1.0 h; After deammoniation in step one, a certain amount of ternary precursor waste is added, and ozone is introduced at a certain rate, followed by heating and stirring for 0.5-2 h; The ternary precursor mother liquor after the reaction in step two is filtered to obtain filtrate and filter residue; The filter residue obtained in step three is fed into another reaction tank, water is added to adjust the slurry, a certain amount of sulfuric acid and reducing agent are added, and the mixture is heated and stirred for leaching for 2-6 h.

[0007] The above-mentioned schemes only recover a limited range of resources, making it difficult to achieve the resource recovery of heavy metals and ammonium salts, resulting in low recovery efficiency. Summary of the Invention

[0008] The purpose of this invention is to provide a comprehensive treatment method for ternary precursor synthesis mother liquor and nickel-iron mother liquor. This invention is based on the separation of acid and salt by ion exchange membrane diffusion dialysis, combined with deammoniation membrane stripping and absorption process, and then carried out metathesis reaction through double displacement electrodialysis, finally producing composite ammonium salt and soda ash, reducing carbon dioxide emissions and achieving resource utilization of heavy metals and salts.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a comprehensive treatment method for ternary precursor synthesis mother liquor and nickel-iron mother liquor, the comprehensive treatment method comprising the following steps:

[0011] (1) The nickel-iron mother liquor is subjected to a first solid-liquid separation to obtain nickel-iron filtrate. The nickel-iron filtrate is subjected to diffusion dialysis treatment to obtain residual acid and metal liquid. The residual acid is subjected to weight removal and concentration treatment to obtain concentrated acid.

[0012] (2) Use the concentrated acid obtained in step (1) to acidify and remove weight from the ternary precursor synthesis mother liquor to obtain acidified liquid and carbon dioxide. Perform a second solid-liquid separation on the acidified liquid to obtain acidified filtrate. Perform a second weight removal treatment on the acidified filtrate to obtain a second weight removal liquid.

[0013] (3) After adjusting the pH of the secondary heavy removal liquid, the secondary heavy removal liquid is subjected to deammoniation treatment to obtain deammoniation liquid and ammonium bicarbonate liquid. The deammoniation liquid and ammonium bicarbonate liquid are subjected to double displacement electrodialysis treatment to obtain dilute brine, dilute ammonium liquid, compound ammonium liquid and soda ash liquid.

[0014] This invention uses ternary precursor synthesis mother liquor and molten metal as raw materials. Through diffusion dialysis and deammoniation, heavy metals and ammonium salts are recovered. Then, double-displacement electrodialysis is used to generate soda ash solution and composite ammonium salt solution, achieving wastewater resource recovery. The molten metal produced after acid separation of the nickel-iron mother liquor can be returned to the upstream synthesis process as raw material. The dilute brine produced after double-displacement electrodialysis of the ternary precursor synthesis mother liquor can be used as a diluent for reagent preparation or as rinsing water for crude products, returned to the upstream process.

[0015] The main component of the ternary precursor synthesis mother liquor described in this invention is NH4. + Na + SO4 2- CO3 2-A mixture consisting of a small amount of NCM (nickel, cobalt, and manganese) exists in the solution as ammonium complex ions and hydroxyl complex ions, which cannot be deeply removed by resin. Adjusting the pH of the solution to ≤5.5 with acid can remove more than 90% of the CO3 in the solution. 2- Avoid NH4 + Na + SO4 2- CO3 2- Mutually induced hydrolysis occurs: The generated gas affects the resin's weight removal efficiency and simultaneously causes NCM complex ions to dissociate into Ni. 2+ Co 2+ Mn 2+ This achieves the goal of deep deweight removal.

[0016] The main component of the deammoniation liquid obtained by this invention is sodium sulfate, and the main components of the ammonium bicarbonate liquid are ammonium carbonate and ammonium bicarbonate. This invention can utilize sodium sulfate to produce soda ash and compound ammonium salts for reuse or sale, achieving the goal of obtaining higher-value products while treating wastewater. Compared with directly selling sodium sulfate products, this invention offers less sales pressure, wider sales channels, and greater market demand, making it economically practical.

[0017] Preferably, the first solid-liquid separation method in step (1) includes pressure filtration and / or precision filtration.

[0018] Preferably, the molar concentration of hydrogen ions in the nickel-iron filtrate in step (1) is 1.4 mol / L to 2 mol / L, for example: 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.8 mol / L or 2 mol / L, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0019] Preferably, the mass concentration of nickel in the nickel-iron filtrate in step (1) is 32 g / L to 45 g / L, for example: 32 g / L, 35 g / L, 38 g / L, 40 g / L or 45 g / L, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0020] Preferably, the mass concentration of iron in the nickel-iron filtrate in step (1) is 2.3 g / L to 4.1 g / L, for example: 2.3 g / L, 2.5 g / L, 2.8 g / L, 3 g / L, 3.5 g / L or 4.1 g / L, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0021] Preferably, the diffusion dialysis treatment in step (1) includes passing the nickel-iron filtrate and pure water together into the diffusion dialysis device.

[0022] The diffusion dialysis described in this invention is a concentration gradient-driven membrane separation technology. During operation, wastewater and pure water flow on opposite sides of an ion exchange membrane. Driven by the concentration difference, and through the selective action of the ion exchange membrane, ions in the wastewater tend to diffuse towards the pure water side. Ions with opposite charges to the membrane surface groups (counterions) can permeate the membrane to the pure water side, while ions with the same charge as the membrane surface groups (identical ions) are repelled by the membrane surface and have difficulty permeating to the pure water side. Compared to other identical ions, hydrogen ions have a smaller hydration radius, lower charge, and higher activity, making it easier to permeate the ion exchange membrane to the pure water side to meet the electroneutrality requirement of the solution. Based on this principle, nickel-iron mother liquor can be separated from sulfuric acid and heavy metal ions using diffusion dialysis technology, achieving the purpose of acid separation and recovery from wastewater.

[0023] Preferably, the ion exchange capacity of the anion exchange membrane used in the diffusion dialysis treatment in step (1) is 0.9 mmol / g to 1.2 mmol / g, for example: 0.9 mmol / g, 1.0 mmol / g, 1.1 mmol / g, 1.2 mmol / g, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0024] Preferably, the mass transfer coefficient of the anion exchange membrane used in the diffusion dialysis treatment in step (1) is ≥10×10⁻⁶. -7 m / s.

[0025] Preferably, during the diffusion dialysis treatment in step (1), the flow rate of the nickel-iron filtrate is 0.2 L / (m²). 2 ·h)~0.5L / (m 2 ·h), for example: 0.2L / (m 2 ·h), 0.25L / (m 2 ·h), 0.3L / (m 2 ·h), 0.4L / (m 2 ·h) or 0.5L / (m 2 •h) etc., are not limited to the listed values; other unlisted values ​​within the range also apply.

[0026] Preferably, in the diffusion dialysis process described in step (1), the influent flow rate ratio of nickel-iron filtrate to pure water is (1.2 to 2.2):1, for example: 1.2:1, 1.5:1, 1.8:1, 2:1 or 2.2:1, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0027] Preferably, during the diffusion dialysis process described in step (1), the inlet temperature of the nickel-iron filtrate and pure water is 15℃~30℃, for example: 15℃, 18℃, 20℃, 25℃ or 30℃, etc., not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0028] Preferably, the weight removal method in step (1) includes resin weight removal.

[0029] Preferably, the resin includes a heavy-duty resin and / or a selective nickel and iron removal resin.

[0030] Preferably, the concentration process in step (1) includes electrodialysis concentration.

[0031] Preferably, the voltage for electrodialysis concentration is 65V to 75V, for example: 65V, 68V, 70V, 72V or 75V, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0032] Preferably, the current for electrodialysis concentration is 60A to 75A, for example: 60A, 62A, 65A, 70A or 75A, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0033] Preferably, the second solid-liquid separation method in step (2) includes any one or a combination of at least two of pressure filtration, precision filtration or ultrafiltration. Typical but non-limiting combinations include a combination of pressure filtration and precision filtration, a combination of pressure filtration and ultrafiltration, or a combination of precision filtration and ultrafiltration.

[0034] Preferably, the mass concentration of sodium sulfate in the acidified filtrate in step (2) is 55 g / L to 130 g / L, for example: 55 g / L, 60 g / L, 80 g / L, 100 g / L or 130 g / L, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0035] Preferably, the mass concentration of ammonia nitrogen in the acidified filtrate in step (2) is 8 g / L to 12 g / L, for example: 8 g / L, 9 g / L, 10 g / L, 11 g / L or 12 g / L, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0036] The ammonia nitrogen mentioned in this invention refers to free ammonia (NH3) and ammonium ions (NH4+) in the solution. 4+ The total amount of ).

[0037] Preferably, the total mass concentration of nickel, cobalt and manganese in the acidified filtrate in step (2) is 0.5 g / L to 2 g / L, for example: 0.5 g / L, 0.8 g / L, 1 g / L, 1.5 g / L or 2 g / L, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0038] Preferably, the carbon dioxide in step (2) is introduced into the dilute ammonium solution obtained in step (3) as the deammoniation receiving solution.

[0039] Preferably, the secondary deweighting process in step (2) includes resin deweighting.

[0040] Preferably, the resin includes a heavy metal removal resin and / or a selective nickel, cobalt, and manganese removal resin.

[0041] Preferably, the pH adjuster for adjusting the secondary heavy removal liquid in step (3) includes caustic soda flakes and / or liquid caustic soda.

[0042] Preferably, the pH in step (3) is >10.

[0043] Preferably, the secondary heavy removal liquid is heated before the deammoniation treatment in step (3).

[0044] Preferably, the deammoniation treatment in step (3) includes passing the secondary heavy removal liquid and the deammoniation receiving liquid into the deammoniation membrane.

[0045] Preferably, the solute in the deammoniation receiving liquid includes carbonic acid and ammonium bicarbonate.

[0046] Preferably, the inlet temperature of the deammoniation treatment in step (3) is 30℃~40℃, for example: 30℃, 32℃, 35℃, 38℃ or 40℃, etc., not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0047] Preferably, in the deammoniation process described in step (3), the circulation flow rates of the deammoniation receiving liquid and the secondary heavy removal liquid are independently 8 m / s. 3 / (m 2 ·h)~10.5m 3 / (m 2 ·h), for example: 8m 3 / (m 2 ·h), 8.5m 3 / (m 2 ·h), 9m 3 / (m 2 ·h), 9.5m 3 / (m 2 ·h), 10m 3 / (m 2 ·h) or 10.5m 3 / (m2 •h) etc., are not limited to the listed values; other unlisted values ​​within the range also apply.

[0048] Preferably, during the deammoniation process in step (3), a deammoniation solution is produced when the pH of the circulating liquid of the secondary heavy removal liquid is <9.

[0049] The ammonia removal process described in this invention is a novel separation technology that combines membrane technology with traditional stripping and absorption processes. Its structure is a hydrophobic hollow fiber membrane. When ammonia-containing wastewater passes through the membrane fiber surface, the water is isolated outside the membrane fibers, while gaseous ammonia nitrogen permeates into the membrane fibers and is absorbed. Ammonia nitrogen exists in a dissociation equilibrium in water. When the pH of the wastewater is maintained above 10 and the temperature is above 20℃, the NH4 in the wastewater phase... + The NH3 will continuously migrate into the absorbent liquid phase as free gaseous NH3. Carbon dioxide is introduced into the front of the absorbent liquid, resulting in the following reactions: NH3 + CO2 + H2O = NH4HCO3, 2NH3 + CO2 + H2O = (NH4)2CO3. This reaction is endothermic; as the absorbent liquid continuously circulates within the tube, NH3 is converted into ionic NH4. + The ammonia is stabilized in the absorption solution, thereby achieving the purpose of removing ammonia nitrogen. Compared with conventional steam deammoniation, the ammonia removal membrane used in this invention is more economical, with an ammonia removal rate of >96% and a lower residual ammonia nitrogen concentration.

[0050] Preferably, liquid alkali is added to adjust the pH during the double displacement electrodialysis treatment in step (3).

[0051] Preferably, the mass concentration of the liquid alkali is 3% to 30%, for example: 3%, 5%, 10%, 20% or 30%, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0052] Preferably, the pH of the double displacement electrodialysis treatment in step (3) is >10.

[0053] Preferably, the voltage of the dual displacement electrodialysis treatment in step (3) is 10V to 30V, for example: 10V, 15V, 20V, 25V or 30V, etc., not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0054] Preferably, the current density of the dual-displacement electrodialysis treatment in step (3) is 300 A / m. 2 ~500A / m 2， For example: 300A / m 2 350A / m 2 400A / m 2 450A / m 2Or 500A / m 2 wait.

[0055] Preferably, the current for the dual displacement electrodialysis treatment in step (3) is 10A to 40A, for example: 10A, 15A, 20A, 30A or 40A, etc., not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0056] The current density described in this invention is only related to the membrane area, therefore it can be controlled separately from voltage and current. While both voltage and current can be controlled separately, they jointly affect the electrodialysis process: if the voltage and current are too low, the ion flux decreases; if the voltage and current are too high, the current efficiency decreases, energy consumption costs increase, and concentration polarization causes water electrolysis to prioritize ion migration. In the dual-displacement electrodialysis treatment described in this invention, the voltage is positively correlated with the membrane stack logarithm, and the current is positively correlated with the membrane area and current density. In this invention, the current density is fixed (depending only on the membrane area and unaffected by energizing conditions), so only the voltage needs to be controlled.

[0057] Preferably, during the dual displacement electrodialysis treatment in step (3), the endpoint is reached when the conductivity of the deammoniation solution is <2 ms / cm.

[0058] The dual-displacement electrodialysis treatment described in this invention achieves conversion while concentrating. Its salt separation is based on the directional movement of ions in an electric field and the selective permeation of the ion exchange membrane. The cation and anion exchange membranes are arranged in a cross pattern and installed parallel to the electrodes on both sides. Under the influence of the electric field, cations migrate towards the cathode, and anions migrate towards the anode. During this process, cations and anions are separated and recombine. The main reaction is: Na₂SO₄ + (NH₄)₂CO₃ + NH₄HCO₃ = (NH₄)₂SO₄ + Na₂CO₃ + NaHCO₃. By adding NaOH to control the pH of the solution, soda ash is obtained: NaHCO₃ + NaOH = Na₂CO₃ + H₂O. Dual-displacement electrodialysis is applied to the treatment of sulfate-type industrial wastewater, converting sulfates, which originally had low economic value, into carbonates, which have higher economic value. Compared with traditional zero-discharge treatment methods for sulfate wastewater, this method offers better economic benefits.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] (1) The present invention can effectively recover the remaining acid and heavy metals in the nickel-iron mother liquor and the ternary precursor synthesis mother liquor. The comprehensive treatment method has high equipment utilization, large processing capacity, stable process operation parameters, and is easy to automate. The overall process route does not introduce external ions, and the system is effectively recycled, reducing wastewater discharge and carbon emissions.

[0061] (2) The method described in this invention can obtain a composite ammonium salt with a nitrogen content of more than 18.6% and a sodium carbonate purity of more than 96.82%. By adjusting the conditions of the recovery process, risks such as product doping and membrane blockage can be avoided, and the composite ammonium salt can be obtained with a nitrogen content of more than 19.88% and a sodium carbonate purity of more than 98.01%. Attached Figure Description

[0062] Figure 1 This is a schematic diagram of the process flow of the integrated treatment method of the ternary precursor synthesis mother liquor and nickel-iron mother liquor described in Embodiment 1 of the present invention.

[0063] Figure 2 This is a schematic diagram of the dual-displacement electrodialysis treatment provided in an embodiment of the present invention. Detailed Implementation

[0064] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0065] The ternary precursor synthesis mother liquor used in the embodiments and comparative examples of this invention mainly consists of sodium sulfate, ammonium carbonate, and trace amounts of nickel-cobalt-manganese complex ions, wherein the sodium ion concentration is 30 g / L, the ammonia nitrogen concentration is 15 g / L, and the nickel-cobalt-manganese concentration is <3 g / L. The nickel-iron mother liquor mainly consists of nickel sulfate, ferrous sulfate, and sulfuric acid, wherein the nickel concentration is 38 g / L and the iron concentration is 3.5 g / L.

[0066] Example 1

[0067] This embodiment provides a comprehensive treatment method for ternary precursor synthesis mother liquor and nickel-iron mother liquor. A schematic diagram of the process flow of the comprehensive treatment method is shown below. Figure 1 As shown, the comprehensive processing method includes the following steps:

[0068] (1) The high-acid nickel-iron mother liquor was filtered by pressure to obtain nickel-iron filtrate. The nickel-iron filtrate and pure water were then passed into a diffusion dialysis device. The anion exchange capacity of the anion exchange membrane in the diffusion dialysis device was 1 mmol / g, and the mass transfer coefficient was ≥10×10⁻⁶. -7 m / s, control the flow rate of nickel-iron filtrate to 0.4 L / (m 2 The pure water flow rate is 0.29 L / (m·h). 2 ·h), with an inlet temperature of 16℃, after metal and acid separation, 88.2% of the hydrogen ions in the first metal liquid are recovered and returned to the front end of the process. The nickel and iron retention rates in the residual acid are 98.6%. The residual acid enters the heavy metal removal resin for deep removal of heavy metals, and the resulting dilute acid is concentrated by electrodialysis. The operating voltage is 70V and the current is 67.1A to obtain concentrated acid. The composition of the nickel-iron filtrate, residual acid and concentrated acid is shown in Table 1 below.

[0069] Table 1

[0070] <![CDATA[H + ]]> Ni Fe Nickel-iron filtrate (g / L) 1.68 35.2 2.44 Residual acid (g / L) 1.48 0.49 0.03 Concentrated acid (g / L) 3.78 \ \

[0071] (2) Add concentrated acid to the ternary synthesis mother liquor to adjust the pH to 5.2. The solution is separated from the solids by an ultrafiltration device with a pore size of 0.1 μm to obtain acidified filtrate. The carbon dioxide generated in the process is introduced into the dilute ammonium solution obtained in step (3) as the deammonium receiving liquid. The acidified filtrate is subjected to secondary deweighting through a resin deweighting system to obtain secondary deweighting liquid. The generated second metal liquid is returned to the front end of the process.

[0072] (3) Add 30% liquid alkali to the secondary heavy removal liquid to adjust the pH to 11.7, heat to 33°C in a water bath, and then introduce it into the ammonia removal unit together with the ammonia removal receiving liquid. The circulation flow rate of the ammonia removal receiving liquid is 8.7 m / s. 3 / (m 2 The circulation velocity of the secondary heavy liquid removal process is 8.2 m / h. 3 / (m 2 •h), when the pH of the circulating liquid from the secondary heavy liquid removal stage is <9, ammonia removal liquid and ammonium bicarbonate liquid are produced. The ammonia removal liquid and ammonium bicarbonate liquid are then passed into a system such as… Figure 2 In the dual-displacement electrodialysis system shown, the operating voltage is set to 26V, the current to 32A, and the current density to 400A / m³. 2 Add 5% liquid alkali to the soda ash tank to adjust the pH to >10. Stop when the conductivity of the deammoniation solution drops to 1.2 ms / cm. This produces brine, dilute ammonium solution, compound ammonium solution and soda ash solution. The brine produced is returned to the front end of the process and the dilute ammonium solution is reused in step (2).

[0073] The concentrations of each material in the acidified filtrate, secondary heavy removal liquid, and deammoniation liquid are shown in Table 2.

[0074] Table 2

[0075]

[0076]

[0077] Example 2

[0078] This embodiment provides a comprehensive treatment method for ternary precursor synthesis mother liquor and nickel-iron mother liquor, the comprehensive treatment method including the following steps:

[0079] (1) The high-acid nickel-iron mother liquor was filtered through a 0.45μm precision filter to obtain nickel-iron filtrate. The nickel-iron filtrate and pure water were then passed into a diffusion dialysis apparatus. The anion exchange membrane in the diffusion dialysis apparatus had an ion exchange capacity of 0.9 mmol / g and a mass transfer coefficient ≥10×10⁻⁶. -7 m / s, control the flow rate of nickel-iron filtrate to 0.25 L / (m 2The pure water flow rate is 0.18 L / (m·h). 2 ·h), with an inlet temperature of 18℃, after metal and acid separation, 85.9% of the hydrogen ions in the first metal liquid are recovered and returned to the front end of the process. The nickel and iron retention rates in the residual acid are 96.9%. The residual acid enters the heavy metal removal resin for deep removal of heavy metals, and the resulting dilute acid is concentrated by electrodialysis. The operating voltage is 70.2V and the current is 63.7A to obtain concentrated acid. The composition of the nickel-iron filtrate, residual acid and concentrated acid is shown in Table 3 below.

[0080] Table 3

[0081] <![CDATA[H + ]]> Ni Fe Nickel-iron filtrate (g / L) 1.53 38.6 3.21 Residual acid (g / L) 1.31 1.20 0.10 Concentrated acid (g / L) 3.55 \ \

[0082] (2) Add concentrated acid to the ternary synthesis mother liquor to adjust the pH to 5.4. The solution is separated from the solids by an ultrafiltration device with a pore size of 0.2 μm to obtain acidified filtrate. The carbon dioxide generated in the process is introduced into the dilute ammonium solution obtained in step (3) as the deammoniation receiving liquid. The acidified filtrate is subjected to secondary deweighting through a resin deweighting system to obtain secondary deweighting liquid. The generated second metal liquid is returned to the front end of the process.

[0083] (3) Add caustic soda flakes to the secondary heavy removal liquid to adjust the pH to 12.4, heat it to 35°C in a water bath, and then introduce it into the ammonia removal unit together with the ammonia removal receiving liquid. The circulation flow rate of the ammonia removal receiving liquid is 10.2 m / s. 3 / (m 2 The circulation velocity of the secondary heavy liquid removal process is 8.5 m / h. 3 / (m 2 •h), when the pH of the circulating liquid from the secondary heavy liquid removal stage is <9, ammonia removal liquid and ammonium bicarbonate liquid are produced. The ammonia removal liquid and ammonium bicarbonate liquid are then passed into a system such as… Figure 2 In the dual-displacement electrodialysis system shown, the operating voltage is set to 21V, the current to 16A, and the current density to 300A / m³. 2 Add 3% liquid alkali to the soda ash tank to adjust the pH to >10. Stop when the conductivity of the deammoniation solution drops to 0.7ms / cm. This produces brine, dilute ammonium solution, compound ammonium solution and soda ash solution. The brine is returned to the front end of the process and the dilute ammonium solution is reused in step (2).

[0084] The concentrations of each material in the acidified filtrate, secondary heavy removal liquid, and deammoniation liquid are shown in Table 4.

[0085] Table 4

[0086]

[0087] Example 3

[0088] This embodiment provides a comprehensive treatment method for ternary precursor synthesis mother liquor and nickel-iron mother liquor, the comprehensive treatment method including the following steps:

[0089] (1) The high-acid nickel-iron mother liquor was filtered through a 0.2 μm precision filter to obtain nickel-iron filtrate. The nickel-iron filtrate and pure water were then passed into a diffusion dialysis apparatus. The anion exchange membrane in the diffusion dialysis apparatus had an ion exchange capacity of 1.2 mmol / g and a mass transfer coefficient ≥10×10⁻⁶. -7 m / s, control the flow rate of nickel-iron filtrate to 0.33 L / (m 2 The pure water flow rate is 0.22 L / (m·h). 2 ·h), with an inlet temperature of 17℃, after metal and acid separation, 86.3% of the hydrogen ions in the first metal liquid are recovered and returned to the front end of the process. The nickel and iron retention rates in the residual acid are 97.7%. The residual acid enters the heavy metal removal resin for deep removal of heavy metals, and the resulting dilute acid is concentrated by electrodialysis. The operating voltage is 70.9V and the current is 74.3A to obtain concentrated acid. The composition of the nickel-iron filtrate, residual acid and concentrated acid is shown in Table 5 below.

[0090] Table 5

[0091] <![CDATA[H + ]]> Ni Fe Nickel-iron filtrate (g / L) 1.89 42.1 2.87 Residual acid (g / L) 1.63 0.97 0.07 Concentrated acid (g / L) 3.9 \ \

[0092] (2) Add concentrated acid to the ternary synthesis mother liquor to adjust the pH to 5.5. The solution is separated from the solids by a pressure filter to obtain acidified filtrate. The carbon dioxide generated in the process is fed into the dilute ammonium solution obtained in step (3) as the deammonium receiving liquid. The acidified filtrate is subjected to secondary deweighting through a resin deweighting system to obtain secondary deweighting liquid. The generated second metal liquid is returned to the front end of the process.

[0093] (3) Add caustic soda flakes to the secondary heavy removal liquid to adjust the pH to 12.6, heat it to 30°C in a water bath, and then introduce it into the deammoniation unit together with the deammoniation receiving liquid. The circulation flow rate of the deammoniation receiving liquid is 9.5 m / s. 3 / (m 2 The circulation velocity of the secondary heavy liquid removal process is 8.4 m / s (h). 3 / (m 2 •h), when the pH of the circulating liquid from the secondary heavy liquid removal stage is <9, ammonia removal liquid and ammonium bicarbonate liquid are produced. The ammonia removal liquid and ammonium bicarbonate liquid are then passed into a system such as… Figure 2 In the dual-displacement electrodialysis system shown, the operating voltage is set to 14V, the current to 12.5A, and the current density to 500A / m³. 2 Add 5% liquid alkali to the soda ash tank to adjust the pH to >10. Stop when the conductivity of the deammoniation solution drops to 0.9ms / cm. This produces brine, dilute ammonium solution, compound ammonium solution and soda ash solution. The brine produced is returned to the front end of the process and the dilute ammonium solution is reused in step (2).

[0094] The concentrations of each material in the acidified filtrate, secondary heavy removal liquid, and deammoniation liquid are shown in Table 6.

[0095] Table 6

[0096]

[0097] Example 4

[0098] The only difference between this embodiment and Embodiment 1 is that the flow rate of the pure water in step (1) is 0.4 L / (m). 2 •h)(The flow rate ratio of nickel-iron filtrate to pure water is 1:1), and other conditions and parameters are exactly the same as in Example 1.

[0099] Example 5

[0100] The only difference between this embodiment and Embodiment 1 is that the flow rate of the pure water in step (1) is 0.16 L / (m). 2 •h)(The flow rate ratio of nickel-iron filtrate to pure water is 2.5:1), and other conditions and parameters are exactly the same as in Example 1.

[0101] Example 6

[0102] The only difference between this embodiment and Embodiment 1 is that the circulation flow rate of the secondary heavy removal liquid in step (3) is 11 m / s. 3 / (m 2 ·h), other conditions and parameters are exactly the same as in Example 1.

[0103] Example 7

[0104] The only difference between this embodiment and Embodiment 1 is that the circulation flow rate of the secondary heavy removal liquid in step (3) is 7.5 m / s. 3 / (m 2 ·h), other conditions and parameters are exactly the same as in Example 1.

[0105] Example 8

[0106] The only difference between this embodiment and embodiment 1 is that the voltage of the double displacement electrodialysis in step (3) is 40V, while the other conditions and parameters are exactly the same as in embodiment 1.

[0107] Example 9

[0108] The only difference between this embodiment and embodiment 1 is that the voltage of the double displacement electrodialysis in step (3) is 5V, while the other conditions and parameters are exactly the same as in embodiment 1.

[0109] Comparative Example 1

[0110] The only difference between this comparative example and Example 1 is that the acid separation and weight removal steps are omitted in step (1), and electrodialysis is used for direct concentration. The other conditions and parameters are exactly the same as those in Example 1.

[0111] Comparative Example 2

[0112] The only difference between this comparative example and Example 1 is that steam deaming is used instead of the deaming membrane in step (3), while the other conditions and parameters are exactly the same as in Example 1.

[0113] Comparative Example 3

[0114] The only difference between this comparative example and Example 1 is that step (3) uses ordinary electrodialysis instead of double displacement electrodialysis, while the other conditions and parameters are exactly the same as in Example 1.

[0115] Performance testing:

[0116] The produced composite ammonium solution and soda ash solution were evaporated to obtain ammonium salt and sodium carbonate, respectively. The yield of ammonium salt and the purity of sodium carbonate were calculated. The test results are shown in Table 7.

[0117] Table 7

[0118] risk Main outputs Ammonium salt N content / % Sodium carbonate purity / % Example 1 \ Compound ammonium, sodium carbonate 19.88 98.01 Example 2 \ Compound ammonium, sodium carbonate 20.36 98.21 Example 3 \ Compound ammonium, sodium carbonate 20.1 98.16 Example 4 Product doping Compound ammonium, sodium carbonate 18.6 96.82 Example 5 Membrane plugging Compound ammonium, sodium carbonate 19.51 97.26 Example 6 Ammonium utilization rate decreased Compound ammonium, sodium carbonate 18.75 97.74 Example 7 Membrane plugging Compound ammonium, sodium carbonate 18.92 97.43 Example 8 Breakdown of membrane stack No output \ \ Example 9 Membrane plugging Compound ammonium, sodium carbonate 18.27 96.33 Comparative Example 1 Film blockage, product doping Compound ammonium, sodium carbonate 15.45 95.68 Comparative Example 2 Different products ammonia, sodium sulfate \ \ Comparative Example 3 Different products Sodium sulfate, ammonium carbonate \ \

[0119] As can be seen from Table 7, and from Examples 1-9, the method of the present invention can achieve a nitrogen content of over 18.27% and a sodium carbonate purity of over 96.33% in the composite ammonium salt without breaking down the membrane stack. By adjusting the conditions of the recovery process, risks such as product doping and membrane blockage can be avoided, and the nitrogen content of the composite ammonium salt can reach over 19.88% and the sodium carbonate purity can reach over 98.01%.

[0120] Comparing Examples 1 and 4-5, it can be seen that in the comprehensive treatment method of ternary precursor synthesis mother liquor and nickel-iron mother liquor described in this invention, during the diffusion dialysis process in step (1), the ratio of nickel-iron filtrate to pure water inlet flow rate affects the treatment effect. Controlling the ratio of nickel-iron filtrate to pure water inlet flow rate at (1.2~2.2):1 yields better treatment effect. If the pure water flow rate is too high, the dialysis rate of acid and nickel-iron metal ions in the metal liquid increases, and the acid concentration in the residual acid produced is too high, affecting subsequent weight removal. This causes iron ions to enter the ternary precursor synthesis mother liquor treatment line as impurities, resulting in a decrease in the purity of the double displacement electrodialysis product. If the pure water flow rate is too low, the dialysis rate of acid in the metal liquid slows down, the acid concentration decreases, requiring secondary or multi-stage concentration, increasing energy consumption, and posing a risk of membrane blockage, resulting in low economic benefits.

[0121] A comparison of Examples 1 and 6-7 shows that in the comprehensive treatment method of the ternary precursor synthesis mother liquor and nickel-iron mother liquor described in this invention, during the deammoniation process in step (3), the circulation flow rate of the secondary heavy removal liquid affects the treatment effect. The circulation flow rate of the secondary heavy removal liquid should be controlled at 8 m / s. 3 / (m 2 ·h)~10.5m 3 / (m 2•h), the treatment effect is better. If the circulation flow rate of the secondary heavy removal liquid is too high, the ammonia gas will escape too quickly, the reaction rate with carbonate in the receiving liquid will decrease, the ammonia gas receiving rate will decrease, and the yield of ammonium salt in double displacement electrodialysis will decrease; if the circulation flow rate of the secondary heavy removal liquid is too low, the ammonia removal time will increase, and the high salt solution will have the risk of membrane blockage, reducing the ammonia removal efficiency.

[0122] A comparison of Examples 1 and 8-9 shows that in the comprehensive treatment method of the ternary precursor synthesis mother liquor and nickel-iron mother liquor described in this invention, the voltage of the double displacement electrodialysis in step (3) affects the treatment effect. Controlling the voltage of the double displacement electrodialysis between 10V and 30V yields better treatment results. If the voltage of the double displacement electrodialysis is too high, the current efficiency decreases, energy consumption costs increase, and it will continuously damage the membrane stack, even causing it to break down and fail. If the voltage of the double displacement electrodialysis is too low, the ion flux is lower, and the purity of the obtained product is lower.

[0123] As can be seen from the comparison between Example 1 and Comparative Example 1, the present invention utilizes diffusion dialysis to separate metals and acids, reducing the difficulty of metal liquid recycling and purifying and recovering acids. Electrodialysis can only concentrate the solution and cannot achieve the separation effect. The unseparated iron enters the ternary synthesis process line as an impurity, directly affecting equipment operation and product quality.

[0124] As can be seen from the comparison between Example 1 and Comparative Example 2, compared with the conventional use of steam to remove ammonia, the ammonia removal membrane used in this invention is more economical, with an ammonia removal rate of >96%, a lower residual ammonia nitrogen concentration, and the escaped ammonia gas can be recycled and recovered in the solution along with carbon dioxide.

[0125] As can be seen from the comparison between Example 1 and Comparative Example 3, the present invention utilizes dual-displacement electrodialysis to simultaneously utilize two salt solutions, thereby giving the product higher value through dual displacement, with a salt utilization rate of >99%. Conventional electrodialysis only has a concentration effect and can only process one solution at a time, with a salt utilization rate of <90%.

[0126] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for comprehensively treating ternary precursor synthesis mother liquor and nickel-iron mother liquor, characterized in that, The comprehensive processing method includes the following steps: (1) Perform a first solid-liquid separation on the nickel-iron mother liquor to obtain nickel-iron filtrate, perform diffusion dialysis on the nickel-iron filtrate to obtain residual acid and metal liquid, and perform weight removal and concentration treatment on the residual acid to obtain concentrated acid; (2) The concentrated acid obtained in step (1) is used to acidify and remove weight from the ternary precursor synthesis mother liquor to obtain acidified liquid and carbon dioxide. The acidified liquid is subjected to a second solid-liquid separation to obtain acidified filtrate. The acidified filtrate is subjected to a second weight removal treatment to obtain a second weight removal liquid. (3) After adjusting the pH of the secondary heavy removal liquid, the secondary heavy removal liquid is subjected to deammoniation treatment to obtain deammoniation liquid and ammonium bicarbonate liquid. The deammoniation liquid and ammonium bicarbonate liquid are subjected to double displacement electrodialysis treatment to obtain brine, brine, compound ammonium liquid and soda ash liquid. In step (2), the mass concentration of sodium sulfate in the acidified filtrate is 55 g / L to 130 g / L, the mass concentration of ammonia nitrogen is 8 g / L to 12 g / L, and the total mass concentration of nickel, cobalt and manganese is 0.5 g / L to 2 g / L.

2. The comprehensive processing method as described in claim 1, characterized in that, Step (1) The first solid-liquid separation method includes pressure filtration and / or precision filtration.

3. The comprehensive processing method as described in claim 1, characterized in that, The molar concentration of hydrogen ions in the nickel-iron filtrate in step (1) is 1.4 mol / L to 2 mol / L.

4. The comprehensive processing method as described in claim 1, characterized in that, The mass concentration of nickel in the nickel-iron filtrate in step (1) is 32 g / L to 45 g / L.

5. The comprehensive processing method as described in claim 1, characterized in that, The mass concentration of iron in the nickel-iron filtrate in step (1) is 2.3 g / L to 4.1 g / L.

6. The comprehensive processing method as described in claim 1, characterized in that, The diffusion dialysis treatment in step (1) includes passing the nickel-iron filtrate and pure water into the diffusion dialysis device.

7. The comprehensive processing method as described in claim 1, characterized in that, The anion exchange capacity of the anion exchange membrane used in the diffusion dialysis treatment in step (1) is 0.9 mmol / g to 1.2 mmol / g.

8. The comprehensive processing method as described in claim 1, characterized in that, The mass transfer coefficient of the anion exchange membrane used in the diffusion dialysis treatment in step (1) is ≥10×10⁻⁶. -7 m / s.

9. The comprehensive processing method as described in claim 1, characterized in that, In step (1), during the diffusion dialysis treatment, the flow rate of the nickel-iron filtrate is 0.2 L / (m). 2 ·h)~0.5L / (m 2 ·h).

10. The comprehensive processing method as described in claim 1, characterized in that, In the diffusion dialysis process described in step (1), the ratio of the influent flow rate of nickel-iron filtrate to pure water is (1.2~2.2):

1.

11. The comprehensive processing method as described in claim 1, characterized in that, In the diffusion dialysis process described in step (1), the inlet temperature of the nickel-iron filtrate and pure water is 15℃~30℃.

12. The comprehensive processing method as described in claim 1, characterized in that, The weight removal method in step (1) includes resin weight removal.

13. The comprehensive processing method as described in claim 12, characterized in that, The resin includes a heavy removal resin and / or a selective nickel and iron removal resin.

14. The comprehensive processing method as described in claim 1, characterized in that, The concentration process in step (1) includes electrodialysis concentration.

15. The comprehensive processing method as described in claim 14, characterized in that, The voltage for electrodialysis concentration is 65V~75V.

16. The comprehensive processing method as described in claim 14, characterized in that, The current for electrodialysis concentration is 60A~75A.

17. The comprehensive processing method as described in claim 1, characterized in that, Step (2) The second solid-liquid separation method includes any one or a combination of at least two of pressure filtration, precision filtration or ultrafiltration.

18. The comprehensive processing method as described in claim 1, characterized in that, The carbon dioxide in step (2) is introduced into the dilute ammonium solution obtained in step (3) as the deammoniation receiving solution.

19. The comprehensive processing method as described in claim 1, characterized in that, The secondary deweighting process described in step (2) includes resin deweighting.

20. The comprehensive processing method as described in claim 19, characterized in that, The resin includes a heavy removal resin and / or a selective removal resin for nickel, cobalt, and manganese.

21. The comprehensive processing method as described in claim 1, characterized in that, The pH adjuster for adjusting the secondary heavy removal liquid in step (3) includes caustic soda flakes and / or liquid caustic soda.

22. The comprehensive processing method as described in claim 1, characterized in that, The pH value in step (3) is >10.

23. The comprehensive processing method as described in claim 1, characterized in that, Before the deammoniation treatment in step (3), the secondary heavy removal liquid is heated.

24. The comprehensive processing method as described in claim 1, characterized in that, The deammoniation treatment in step (3) includes passing the secondary heavy removal liquid and the deammoniation receiving liquid into the deammoniation membrane.

25. The comprehensive processing method as described in claim 24, characterized in that, The solutes in the deammoniation receiving solution include carbonic acid and ammonium bicarbonate.

26. The comprehensive processing method as described in claim 1, characterized in that, The inlet temperature of the deammoniation treatment in step (3) is 30℃~40℃.

27. The comprehensive processing method as described in claim 24, characterized in that, In step (3), during the deammoniation treatment, the circulation flow rates of the deammoniation receiving liquid and the secondary heavy removal liquid are independently 8 m / s. 3 / (m 2 ·h)~10.5m 3 / (m 2 ·h).

28. The comprehensive processing method as described in claim 1, characterized in that, In the process of deammoniation treatment described in step (3), deammoniation liquid is produced when the pH of the circulating liquid of the secondary heavy removal liquid is <9.

29. The comprehensive processing method as described in claim 1, characterized in that, In step (3), liquid alkali is added to adjust the pH during the double displacement electrodialysis process.

30. The comprehensive processing method as described in claim 29, characterized in that, The mass concentration of the liquid alkali is 3% to 30%.

31. The comprehensive processing method as described in claim 1, characterized in that, In step (3), the pH of the double displacement electrodialysis treatment is >10.

32. The comprehensive processing method as described in claim 1, characterized in that, The voltage for the dual displacement electrodialysis treatment in step (3) is 10V~30V.

33. The comprehensive processing method as described in claim 1, characterized in that, The current density of the dual-displacement electrodialysis treatment in step (3) is 300 A / m. 2 ~500A / m 2 .

34. The comprehensive processing method as described in claim 1, characterized in that, The current for the dual displacement electrodialysis treatment in step (3) is 10A~40A.

35. The comprehensive processing method as described in claim 1, characterized in that, In step (3), the endpoint is reached when the conductivity of the deammoniation solution is <2 ms / cm during the dual displacement electrodialysis process.

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