Comprehensive treatment method for ternary precursor synthesis mother liquor and ferronickel mother liquor

Abstract

The invention provides a comprehensive treatment method of ternary precursor synthesis mother liquor and ferronickel mother liquor, which comprises the following steps: (1) carrying out solid-liquid separation on the ferronickel mother liquor, carrying out diffusion dialysis treatment on the obtained ferronickel filtrate to obtain residual acid and molten metal, and carrying out weight removal and concentration treatment on the residual acid to obtain concentrated acid; (2) carrying out acidification and heavy metal removal treatment on the ternary precursor synthesis mother liquor by using concentrated acid to obtain acidizing liquid and carbon dioxide, carrying out solid-liquid separation on the acidizing liquid to obtain acidizing filtrate, and carrying out secondary heavy metal removal treatment on the acidizing filtrate to obtain secondary heavy metal removal liquid; and (3) after adjusting the pH value of the secondary heavy metal removal solution, carrying out deamination treatment on the secondary heavy metal removal solution to obtain a deamination solution and an ammonium bicarbonate solution, and carrying out double replacement electrodialysis treatment on the deamination solution and the ammonium bicarbonate solution to obtain light salt brine, a light ammonium solution, a composite ammonium solution and a sodium carbonate solution. According to the method, the ternary precursor synthesis mother liquor and the ferronickel mother liquor are comprehensively treated, composite ammonium salt and sodium carbonate are produced, and resource recycling is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of resource recovery, and relates to a comprehensive treatment method for ternary precursor synthesis mother liquor and nickel-iron mother liquor. Background Art

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

[0003] At present, ternary cathode materials in industry are generally prepared by calcining hydroxides of Ni, Co, and Mn three elements as precursors with lithium. The mainstream process for generating ternary material precursors is the co-precipitation method. By preparing a solution of mixed metal ions with a certain concentration, NaOH is used as the precipitant and ammonia water is used as the complexing agent, and they are added in a countercurrent manner. The solid obtained after the solid-liquid separation of the synthesized slurry is the ternary precursor material, and the filtrate is a sulfate solution containing ammonium and sodium. This solution also contains a small amount of heavy metal ions such as nickel, cobalt, and manganese. Therefore, it is necessary to effectively treat this ternary wastewater for resource utilization.

[0004] The iron-containing metal liquid is synthesized into iron phosphate through batching. The filtrate after the solid-liquid separation of the synthesized slurry is the nickel-iron mother liquor, and its main component is a sulfate solution containing nickel and iron. There is still a large amount of acid not fully utilized in this solution. At present, the main methods for treating such high-acid solutions containing heavy metals are focused on recovering the acid resources therein.

[0005] CN112010479A discloses a treatment process for ternary precursor wastewater, specifically: the mother liquor generated during the preparation of ternary precursors is subjected to stripping treatment to obtain sodium sulfate; the washing water generated during the preparation of ternary precursors is subjected to multi-stage reverse osmosis membrane treatment, and the concentrated liquid generated during the multi-stage reverse osmosis membrane treatment is merged into the mother liquor for further treatment, and the dialysate generated during the multi-stage reverse osmosis membrane treatment is recycled for production to realize the circular treatment of ternary precursor wastewater.

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

[0007] The above-mentioned scheme has a single type of recycled resources, making it difficult to achieve the resource recovery of heavy metals and ammonium salts, and the recovery efficiency is relatively low. Summary of the Invention

[0008] The purpose of the present invention is to provide a comprehensive treatment method for ternary precursor synthesis mother liquor and nickel-iron mother liquor. Based on the diffusion dialysis of ion exchange membranes to separate acids and salts, combined with the ammonia stripping and absorption process of the deammoniation membrane, and then through double displacement electrodialysis for metathesis reaction, composite ammonium salts and soda ash are finally produced, reducing carbon dioxide emissions and achieving the resource recovery of heavy metals and salts.

[0009] To achieve the purpose of this invention, the following technical solutions are adopted:

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

[0011] (1) Perform the first solid-liquid separation on the nickel-iron mother liquor to obtain a nickel-iron filtrate, perform diffusion dialysis treatment on the nickel-iron filtrate to obtain residual acid and metal liquid, and perform heavy metal removal and concentration treatment on the residual acid to obtain concentrated acid;

[0012] (2) Use the concentrated acid obtained in step (1) to perform acidification and heavy metal removal treatment on the ternary precursor synthesis mother liquor to obtain an acidified liquid and carbon dioxide, perform the second solid-liquid separation on the acidified liquid to obtain an acidified filtrate, and perform secondary heavy metal removal treatment on the acidified filtrate to obtain a secondary heavy metal removal liquid;

[0013] (3) After adjusting the pH of the secondary heavy metal removal liquid, perform deammoniation treatment on the secondary heavy metal removal liquid to obtain a deammoniated liquid and a carbon ammonium liquid, and perform double displacement electrodialysis treatment on the deammoniated liquid and the carbon ammonium liquid to obtain light brine, light ammonium liquid, composite ammonium liquid, and soda ash liquid.

[0014] The present invention uses ternary precursor synthesis mother liquor and metal liquid as raw materials, recovers heavy metals and ammonium salts through diffusion dialysis and deammoniation, and then uses double displacement electrodialysis to generate soda ash liquid and composite ammonium salt liquid to achieve the purpose of wastewater resource recovery. The metal liquid generated after the nickel-iron mother liquor is acid-separated can be used as a raw material to return to the front-end synthesis process for continued use. The light brine generated after the ternary precursor synthesis mother liquor is treated by double displacement electrodialysis can be used as a dilution liquid for preparing pharmaceuticals or a flushing water for crude products to return to the front-end for use.

[0015] The composition of the ternary precursor synthesis mother liquor described in the present invention is mainly NH 4 + , Na + , SO 4 2- , CO 3 2-A mixture composed of [substance] and a small amount of NCM (nickel, cobalt, manganese). At this time, NCM exists in the solution in the form of ammonia complex ions and hydroxyl complex ions and cannot be deeply removed by the resin. Adding acid to adjust the solution pH ≤ 5.5 can remove more than 90% of CO in the solution. 3 2- , to avoid NH 4 + , Na + , SO 4 2- , CO 3 2- from undergoing mutual promotion of hydrolysis: Generating gas affects the heavy metal removal effect of the resin, and at the same time dissociates the NCM complex ions into Ni 2+ , Co 2+ , Mn 2+ so as to achieve the purpose of deep heavy metal removal.

[0016] The main component of the deammoniated liquid obtained in the present invention is sodium sulfate, and the main components of the ammonium carbonate solution are ammonium carbonate and ammonium bicarbonate. The present invention can use sodium sulfate to produce soda ash and compound ammonium salts for reuse or external sales, realizing the harvest of products with higher value while treating wastewater. Compared with directly selling sodium sulfate products, the sales pressure is smaller, the sales channels are wider, and the market demand is greater, having economic practicality.

[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. It is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0019] Preferably, the mass concentration of nickel element 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. It is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0020] Preferably, the mass concentration of iron element 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. It is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

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

[0022] The diffusion dialysis described in the present invention is a membrane separation technology driven by a concentration gradient. During the operation of the diffusion dialysis device, the wastewater and pure water flow on both sides of the ion exchange membrane respectively. Driven by the concentration difference, through the selective action of the ion exchange membrane, the ions in the wastewater tend to diffuse to the pure water side. The ions with opposite charges to the groups on the membrane surface (counter ions) can pass through the membrane to reach the pure water side, while the ions with the same charges as the groups on the membrane surface (co-ions) are difficult to pass through the ion exchange membrane to reach the pure water side due to the repulsive force on the membrane surface. Compared with other co-ions, hydrogen ions have a small hydration radius, low charge and high activity, and are more likely to pass through the ion exchange membrane to reach the pure water side to meet the requirement of electrical neutrality of the solution. According to this principle, the nickel-iron mother liquor can be separated from sulfuric acid and heavy metal ions by diffusion dialysis technology to achieve the purpose of separating and recovering the acid in the 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. It is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0024] Preferably, the mass transfer coefficient of the anion exchange membrane used in the diffusion dialysis treatment in step (1) is ≥10×10 -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 / (m 2 ·h) to 0.5 L / (m 2 ·h), for example: 0.2 L / (m 2 ·h), 0.25 L / (m 2 ·h), 0.3 L / (m 2 ·h), 0.4 L / (m 2 ·h) or 0.5 L / (m 2 ·h), etc. It is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0026] Preferably, during the diffusion dialysis treatment in step (1), the inlet flow rate ratio of the 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. It is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0027] Preferably, during the diffusion dialysis treatment in step (1), the inlet temperatures of the nickel-iron filtrate and pure water are 15°C to 30°C, for example: 15°C, 18°C, 20°C, 25°C, or 30°C, etc. It is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0028] Preferably, the method for removing heavy metals in step (1) includes resin heavy metal removal.

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

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

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

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

[0033] Preferably, the method of the second solid-liquid separation 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 the combination of pressure filtration and precision filtration, the combination of pressure filtration and ultrafiltration, or the combination of precision filtration and ultrafiltration, etc.

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

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

[0036] The ammonia nitrogen in the present invention refers to the total amount of free ammonia (NH 3 ) and ammonium ions (NH 4+ ) in the solution.

[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. It is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0038] Preferably, the carbon dioxide in step (2) is introduced into the light ammonium solution obtained in step (3) as the ammonia removal receiving liquid.

[0039] Preferably, the method of the secondary heavy metal removal treatment in step (2) includes resin heavy metal removal.

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

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

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

[0043] Preferably, the secondary heavy metal removal liquid is heat-treated before the ammonia removal treatment in step (3).

[0044] Preferably, the ammonia removal treatment in step (3) includes introducing the secondary heavy metal removal liquid and the ammonia removal receiving liquid into an ammonia removal membrane.

[0045] Preferably, the solute of the ammonia removal receiving liquid includes carbonic acid and ammonium bicarbonate.

[0046] Preferably, the inlet liquid temperature of the ammonia removal treatment in step (3) is 30°C to 40°C. For example: 30°C, 32°C, 35°C, 38°C, or 40°C, etc. It is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0047] Preferably, during the ammonia removal treatment in step (3), the circulation flow rates of the ammonia removal receiving liquid and the secondary heavy metal removal liquid are independently 8 m 3 / (m 2 ·h) to 10.5 m 3 / (m 2 ·h). For example: 8 m 3 / (m 2 ·h), 8.5 m 3 / (m 2 ·h), 9 m 3 / (m 2 ·h), 9.5 m 3 / (m 2 ·h), 10 m 3 / (m 2 ·h), or 10.5 m 3 / (m2 · h), etc., not limited to the listed values, and other unlisted values within this value range are equally applicable.

[0048] Preferably, during the deamination treatment in step (3), when the pH of the circulating liquid of the secondary heavy metal removal liquid < 9, the deamination liquid is produced.

[0049] The deamination process of the present invention is a new separation technology that combines a membrane with traditional stripping and absorption processes. Its structure is a hydrophobic hollow fiber membrane. When the ammonia-containing wastewater passes through the surface of the membrane filaments, water is isolated outside the membrane filaments, while gaseous ammonia nitrogen penetrates into the interior of the membrane filaments 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 greater than 20 °C, NH in the wastewater phase 4 + will continuously turn into free gaseous NH 3 and migrate to the absorption liquid phase. Carbon dioxide is introduced at the front end of the absorption liquid, and the following reactions occur: NH 3 + CO 2 + H 2 O = NH 4 HCO 3 , 2NH 3 + CO 2 + H 2 O = (NH 4 ) 2 CO 3 . This reaction is an endothermic reaction. As the absorption liquid continuously circulates in the tube side, NH 3 is converted into ionic NH 4 + and is stabilized in the absorption solution, thereby achieving the purpose of removing ammonia nitrogen. Compared with the conventional use of steam for deamination, the deamination membrane used in the present invention has economy, and the ammonia removal rate > 96%, and the ammonia nitrogen residual concentration is lower.

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

[0051] Preferably, the mass concentration of the liquid caustic soda is 3% - 30%, for example: 3%, 5%, 10%, 20% or 30%, etc., not limited to the listed values, and other unlisted values within this value range are equally applicable.

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

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

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

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

[0056] The current density described in the present invention is only related to the membrane area, so it can be controlled separately from the voltage and current. The voltage and current can be controlled separately, and both jointly affect the electrodialysis process: if the voltage and current are too small, the ion flux decreases. If the voltage and current are too large, the current efficiency decreases, the energy consumption cost increases, and concentration polarization causes water electrolysis to take precedence over ion migration. The voltage for the dual-displacement electrodialysis treatment described in the present invention is positively correlated with the number of membrane pairs in the membrane stack, and the current is positively correlated with the membrane area and current density. In the present invention, the current density is fixed (only depends on the membrane area and is not affected by the energization conditions), so only the voltage needs to be controlled.

[0057] Preferably, during the dual-displacement electrodialysis treatment in step (3), the end point is reached when the conductivity of the deammoniated liquid < 2 ms / cm.

[0058] The dual-displacement electrodialysis treatment described in the present invention can achieve the purpose of conversion while concentrating. The basic basis for salt separation is the directional movement of ions in an electric field and the selective permeation of ion exchange membranes. The cation and anion exchange membranes are arranged crosswise and installed parallel to the electrodes on both sides. Under the action of an electric field, cations migrate towards the cathode and anions migrate towards the anode. During this process, cations and anions are separated and recombined. The main reaction is: Na 2 SO 4 +(NH 4 ) 2 CO 3 +NH 4 HCO 3 =(NH 4 ) 2 SO 4 +Na2 CO 3 + NaHCO 3 , by adding NaOH to control the pH of the solution, soda ash is obtained: NaHCO 3 + NaOH = Na 2 CO 3 + H 2 O. The double displacement electrodialysis is applied to the treatment project of sulfate-type industrial wastewater, converting sulfates with relatively low economic value into carbonates with higher economic value, and having better economic benefits compared with the traditional zero-discharge treatment method for sulfate wastewater.

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

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

[0061] (2) The nitrogen content of the composite ammonium salt obtained by the method of the present invention can reach more than 18.6%, and the purity of sodium carbonate can reach more than 96.82%. By adjusting the conditions of the recovery process, not only can the risks of product doping and membrane blocking be avoided, but the nitrogen content of the composite ammonium salt can reach more than 19.88%, and the purity of sodium carbonate can reach more than 98.01%. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0063] Figure 2 is a schematic diagram of the double displacement electrodialysis treatment provided in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0064] The technical solution of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0065] The main components of the ternary precursor synthesis mother liquor used in the examples and comparative examples of the present invention are sodium sulfate, ammonium carbonate and trace nickel-cobalt-manganese complex ions, where the sodium ion concentration is 30 g / L, the ammonia-nitrogen concentration is 15 g / L, and the nickel-cobalt-manganese concentration < 3 g / L. The main components of the nickel-iron mother liquor are nickel sulfate, ferrous sulfate and sulfuric acid, where 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. The process flow schematic diagram of the comprehensive treatment method is as shown in Figure 1 the following, and the comprehensive treatment method includes the following steps:

[0068] (1) Filter the high-acid nickel-iron mother liquor by pressure filtration to obtain nickel-iron filtrate. Pass the nickel-iron filtrate and pure water into a diffusion dialysis device together. The ion exchange capacity of the anion exchange membrane in the diffusion dialysis device is 1 mmol / g, and the mass transfer coefficient ≥ 10×10 -7 m / s. Control the flow rate of the nickel-iron filtrate to be 0.4 L / (m 2 ·h), the flow rate of pure water to be 0.29 L / (m 2 ·h), and the inlet liquid temperature to be 16 °C. After separating metal and acid, 88.2% of the hydrogen ions in the first metal liquid are recovered and returned to the front end of the process. The retention rates of nickel and iron in the residual acid are 98.6%. The residual acid enters the heavy metal removal resin to deeply remove heavy metals, and dilute acid is obtained for electrodialysis concentration. The operating voltage is 70 V and the current is 67.1 A to obtain concentrated acid. Among them, the compositions of the nickel-iron filtrate, residual acid, and concentrated acid are 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 passes through an ultrafiltration device with a pore size of 0.1 μm to separate solids, obtaining acidified filtrate. The carbon dioxide generated during the process is introduced into the light ammonium solution obtained in step (3) as a deammoniation receiving liquid. The acidified filtrate undergoes secondary heavy metal removal through a resin heavy metal removal system to obtain a secondary heavy metal removal liquid, and the generated second metal liquid is returned to the front end of the process;

[0072] (3) Add 30% liquid alkali to the secondary heavy metal removal liquid to adjust the pH to 11.7. After heating in a water bath to 33 °C, it enters the deammoniation device together with the deammoniation receiving liquid. The circulation flow rate of the deammoniation receiving liquid is 8.7 m 3 / (m 2 ·h), and the circulation flow rate of the secondary heavy metal removal liquid is 8.2 m 3 / (m 2 ·h). When the pH of the circulating liquid of the secondary heavy metal removal liquid < 9, deammoniated liquid and ammonium bicarbonate liquid are produced. Pass the deammoniated liquid and ammonium bicarbonate liquid into the double replacement electrodialysis system as shown in Figure 2 the following. Set the operating voltage to 26 V, the current to 32 A, and the current density to 400 A / m 2, adjust the pH > 10 by adding 5% liquid caustic soda to the soda ash liquid tank, and stop when the conductivity of the deammoniated liquid drops to 1.2 ms / cm, producing light brine, light ammonium liquid, composite ammonium liquid and soda ash liquid. Among them, the produced light brine is returned to the front end of the process, and the light ammonium liquid is recycled to step (2);

[0073] Among them, the concentrations of various materials in the acidified filtrate, secondary heavy metal removal liquid and deammoniated liquid are shown in Table 2:

[0074] Table 2

[0075]

[0076]

[0077] Example 2

[0078] This example provides a comprehensive treatment method for ternary precursor synthesis mother liquor and nickel-iron mother liquor. The comprehensive treatment method includes the following steps:

[0079] (1) Pass the high-acid nickel-iron mother liquor through a 0.45 μm precision filtration device to obtain a nickel-iron filtrate. Pass the nickel-iron filtrate and pure water into a diffusion dialysis device. The ion exchange capacity of the anion exchange membrane in the diffusion dialysis device is 0.9 mmol / g, and the mass transfer coefficient ≥ 10×10 -7 m / s, control the flow rate of the nickel-iron filtrate to be 0.25 L / (m 2 ·h), the flow rate of pure water to be 0.18 L / (m 2 ·h), the inlet liquid temperature is 18 °C. After separating the metal and the acid, 85.9% of the hydrogen ions recovered in the first metal liquid are returned to the front end of the process. The retention rates of nickel and iron in the residual acid are 96.9%. The residual acid enters the heavy metal removal resin to deeply remove heavy metals, and dilute acid is obtained for electrodialysis concentration. The operating voltage is 70.2 V and the current is 63.7 A to obtain concentrated acid. Among them, the compositions of the nickel-iron filtrate, residual acid and concentrated acid are 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 passes through a ultrafiltration device with a pore size of 0.2 μm to separate solids, obtaining an acidified filtrate. The carbon dioxide generated during the process is introduced into the light ammonium liquid obtained in step (3) as a deammoniation receiving liquid. The acidified filtrate undergoes secondary heavy metal removal through a resin heavy metal removal system to obtain a secondary heavy metal removal liquid, and the produced second metal liquid is returned to the front end of the process;

[0083] (3) Add flake caustic soda to the secondary heavy metal removal liquid to adjust the pH to 12.4, heat it in a water bath to 35 °C, and then enter the deammoniation device together with the deammoniation receiving liquid. The circulating flow rate of the deammoniation receiving liquid is 10.2 m3 / (m 2 ·h), the circulation flow rate of the secondary heavy metal removal liquid is 8.5 m 3 / (m 2 ·h). When the pH of the circulating liquid of the secondary heavy metal removal liquid < 9, ammonia removal liquid and ammonium bicarbonate liquid are produced. The ammonia removal liquid and the ammonium bicarbonate liquid are introduced into the double displacement electrodialysis system as shown in Figure 2 . The operating voltage is set at 21 V, the current is 16 A, and the current density is 300 A / m 2 . 3% liquid caustic soda is added to the soda ash liquid tank to adjust the pH > 10. When the conductivity of the ammonia removal liquid drops to 0.7 ms / cm, it stops, and fresh brine, fresh ammonium liquid, composite ammonium liquid and soda ash liquid are produced. Among them, the produced fresh brine returns to the front end of the process, and the fresh ammonium liquid is recycled to step (2);

[0084] Among them, the concentrations of each material in the acidified filtrate, secondary heavy metal removal liquid and ammonia removal liquid are shown in Table 4:

[0085] Table 4

[0086]

[0087] Example 3

[0088] This example provides a comprehensive treatment method for the ternary precursor synthesis mother liquor and the nickel-iron mother liquor. The comprehensive treatment method includes the following steps:

[0089] (1) The high-acid nickel-iron mother liquor is passed through a 0.2 μm precision filtration device to obtain a nickel-iron filtrate. The nickel-iron filtrate and pure water are introduced into a diffusion dialysis device together. The ion exchange capacity of the anion exchange membrane in the diffusion dialysis device is 1.2 mmol / g, and the mass transfer coefficient ≥ 10×10 -7 m / s. The flow rate of the nickel-iron filtrate is controlled at 0.33 L / (m 2 ·h), the flow rate of pure water is 0.22 L / (m 2 ·h), and the inlet liquid temperature is 17 °C. After the separation of metal and acid, 86.3% of the hydrogen ions recovered in the first metal liquid are returned to the front end of the process. The retention rates of nickel and iron in the residual acid are 97.7%. The residual acid enters the heavy metal removal resin for deep removal of heavy metals, and dilute acid is obtained for electrodialysis concentration. The operating voltage is 70.9 V and the current is 74.3 A to obtain concentrated acid. Among them, the compositions of the nickel-iron filtrate, residual acid and concentrated acid are as 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 the ternary synthesis mother liquor and concentrated acid to adjust the pH to 5.5. The solution is separated by a pressure filtration device to obtain an acidified filtrate. The carbon dioxide generated during the process is introduced into the dilute ammonium solution obtained in step (3) as the ammonia removal receiving liquid. The acidified filtrate is subjected to secondary heavy metal removal through a resin heavy metal removal system to obtain a secondary heavy metal removal liquid, and the generated secondary metal liquid is returned to the front end of the process;

[0093] (3) Add caustic soda to the secondary heavy metal removal liquid to adjust the pH to 12.6. After heating in a water bath to 30 °C, it enters the ammonia removal device together with the ammonia removal receiving liquid. The circulation flow rate of the ammonia removal receiving liquid is 9.5 m 3 / (m 2 ·h), and the circulation flow rate of the secondary heavy metal removal liquid is 8.4 m 3 / (m 2 ·h). When the pH of the circulating liquid of the secondary heavy metal removal liquid < 9, ammonia removal liquid and ammonium bicarbonate liquid are produced. The ammonia removal liquid and ammonium bicarbonate liquid are introduced into the dual displacement electrodialysis system as shown in Figure 2 . Set the operating voltage to 14 V, the current to 12.5 A, and the current density to 500 A / m 2 . Add 5% liquid caustic soda to the soda ash liquid tank to adjust the pH > 10. Stop when the conductivity of the ammonia removal liquid drops to 0.9 ms / cm, and produce fresh brine, dilute ammonium solution, composite ammonium solution and soda ash liquid. Among them, the produced fresh brine is returned to the front end of the process, and the dilute ammonium solution is recycled to step (2);

[0094] Among them, the concentrations of various materials in the acidified filtrate, secondary heavy metal removal liquid and ammonia removal liquid are shown in Table 6:

[0095] Table 6

[0096]

[0097] Example 4

[0098] The difference between this example and Example 1 is only that the flow rate of the pure water described 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 those in Example 1.

[0099] Example 5

[0100] The difference between this example and Example 1 is only that the flow rate of the pure water described 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 those in Example 1.

[0101] Example 6

[0102] The difference between this example and Example 1 is only that the circulation flow rate of the secondary heavy metal removal liquid described in step (3) is 11 m 3 / (m2 ·h), and other conditions and parameters are exactly the same as those in Example 1.

[0103] Example 7

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

[0105] Example 8

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

[0107] Example 9

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

[0109] Comparative Example 1

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

[0111] Comparative Example 2

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

[0113] Comparative Example 3

[0114] The difference between this comparative example and Example 1 is only that ordinary electrodialysis is used to replace double replacement electrodialysis in step (3), and other conditions and parameters are exactly the same as those in Example 1.

[0115] Performance test:

[0116] The produced composite ammonium solution and soda ash solution are subjected to evaporation treatment to obtain ammonium salt and sodium carbonate respectively. Calculate the yield of ammonium salt and detect the purity of sodium carbonate. The test results are shown in Table 7:

[0117] Table 7

[0118] Risk Main products 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 blockage Compound ammonium, sodium carbonate 19.51 97.26 Example 6 Decrease in ammonium utilization rate Compound ammonium, sodium carbonate 18.75 97.74 Example 7 Membrane blockage Compound ammonium, sodium carbonate 18.92 97.43 Example 8 Stack membrane breakdown No output \ \ Example 9 Membrane blockage Compound ammonium, sodium carbonate 18.27 96.33 Comparative example 1 Membrane blockage, product doping Compound ammonium, sodium carbonate 15.45 95.68 Comparative example 2 Different products Ammonia water, sodium sulfate \ \ Comparative example 3 Different products Sodium sulfate, ammonium carbonate \ \

[0119] As can be seen from Table 7, from Examples 1-9, it can be obtained that in the method of the present invention, without breaking through the membrane stack, the nitrogen content of the composite ammonium salt can reach more than 18.27%, and the purity of sodium carbonate can reach more than 96.33%. By adjusting the conditions of the recovery process, not only can risks such as product doping and membrane blockage be avoided, but the nitrogen content of the composite ammonium salt can reach more than 19.88%, and the purity of sodium carbonate can reach more than 98.01%.

[0120] From the comparison between Example 1 and Examples 4-5, in the comprehensive treatment method of the ternary precursor synthesis mother liquor and the nickel-iron mother liquor of the present invention, during the diffusion dialysis process in step (1), the influent flow rate ratio of the nickel-iron filtrate to pure water will affect the treatment effect. Controlling the influent flow rate ratio of the nickel-iron filtrate to pure water at (1.2-2.2):1 results in better treatment effects. If the pure water flow rate is too large, the dialysis rate of acid and nickel-iron metal ions in the metal solution increases, and the acid concentration in the produced residual acid is too high, affecting subsequent heavy metal removal, causing iron ions to enter the treatment line of the ternary precursor synthesis mother liquor as impurities, and leading to a decrease in the purity of the products produced by double replacement electrodialysis; if the pure water flow rate is too small, the dialysis rate of acid in the metal solution slows down, the acid concentration decreases, secondary or multi-stage concentration is required, the energy consumption increases, and there is a risk of membrane blockage, resulting in low economic benefits.

[0121] From the comparison between Example 1 and Examples 6-7, in the comprehensive treatment method of the ternary precursor synthesis mother liquor and the nickel-iron mother liquor of the present invention, during the deammoniation process in step (3), the circulation flow rate of the secondary heavy metal removal liquid will affect the treatment effect. Controlling the circulation flow rate of the secondary heavy metal removal liquid at 8m 3 / (m 2 ·h) to 10.5m 3 / (m 2 ·h) results in better treatment effects. If the circulation flow rate of the secondary heavy metal removal liquid is too large, ammonia gas escapes too quickly, the reaction rate with carbonate ions in the receiving liquid decreases, the ammonia gas receiving rate decreases, and the ammonium salt production rate of double replacement electrodialysis decreases; if the circulation flow rate of the secondary heavy metal removal liquid is too small, the deammoniation time increases, and there is a risk of membrane blockage in the high-salt solution, reducing the deammoniation efficiency.

[0122] From the comparison between Example 1 and Examples 8-9, in the comprehensive treatment method of the ternary precursor synthesis mother liquor and the nickel-iron mother liquor of the present invention, during the double replacement electrodialysis process in step (3), the voltage of the double replacement electrodialysis will affect the treatment effect. Controlling the voltage of the double replacement electrodialysis at 10V-30V results in better treatment effects. If the voltage of the double replacement electrodialysis is too large, the current efficiency decreases, the energy consumption cost increases, and it will continuously damage the membrane stack and even break through the membrane stack, causing it to fail; if the voltage of the double replacement electrodialysis is too small, the ion flux is smaller, and the purity of the obtained product is lower.

[0123] From the comparison between Example 1 and Comparative Example 1, it can be seen that the present invention can separate metals and acids by diffusion dialysis, reduce the difficulty of recycling metal liquid and purify and recover 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 the equipment operation and product quality.

[0124] From the comparison between Example 1 and Comparative Example 2, it can be seen that compared with the conventional use of steam for ammonia removal, the use of ammonia removal membrane in the present invention has economy, the ammonia removal rate > 96%, the residual concentration of ammonia nitrogen is lower, and the escaped ammonia gas can be comprehensively utilized with carbon dioxide and recovered in the solution.

[0125] From the comparison between Example 1 and Comparative Example 3, it can be seen that the present invention can utilize two salt solutions simultaneously by double displacement electrodialysis, endow the product with higher value through double displacement, the salt utilization rate > 99%, while conventional electrodialysis only has a concentration effect and can only process one solution at a time, and the salt utilization rate < 90%.

[0126] The applicant declares that the above description is only the specific implementation manner 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 thought of by any person skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and disclosure scope of the present invention.

Claims

1. A comprehensive treatment method for ternary precursor synthesis mother liquor and nickel-iron mother liquor, characterized in that: The comprehensive treatment method comprises the following steps: (1) the first solid-liquid separation is carried out to ferronickel mother liquor to obtain ferronickel filtered liquid, ferronickel filtered liquid is carried out to diffusion dialysis process to obtain residual acid and molten metal, residual acid is removed from weight and concentrated to obtain concentrated acid; (2) using the concentrated acid obtained in step (1) to perform an acidification and deweighting treatment on the ternary precursor synthesis mother liquor to obtain an acidified liquid and carbon dioxide, performing a second solid-liquid separation on the acidified liquid to obtain an acidified filtrate, and performing a secondary deweighting treatment on the acidified filtrate to obtain a secondary deweighting liquid; (3) After adjusting the pH of the secondary deweighting liquid, the secondary deweighting liquid is subjected to a deammoniation treatment to obtain a deammoniation liquid and a carbonate ammonium liquid, and the deammoniation liquid and the carbonate ammonium liquid are subjected to a double displacement electrodialysis treatment to obtain a dilute brine, a dilute ammonium liquid, a composite ammonium liquid and a pure alkali liquid.

2. The comprehensive treatment method according to claim 1, characterized in that: Step (1) The first solid-liquid separation method includes filter pressing and / or precision filtration; Preferably, the molar concentration of hydrogen ions in the nickel-iron filtrate in step (1) is 1.4 mol / L to 2 mol / L; Preferably, the mass concentration of nickel in the nickel-iron filtrate in step (1) is 32 g / L to 45 g / L; Preferably, the mass concentration of iron in the nickel-iron filtrate in step (1) is 2.3 g / L to 4.1 g / L.

3. The comprehensive treatment method according to claim 1 or 2, characterized in that: The diffusion dialysis treatment in step (1) comprises passing the nickel-iron filtrate and pure water into a diffusion dialysis device; 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; Preferably, the mass transfer coefficient of the anion exchange membrane used in the diffusion dialysis treatment in step (1) is ≥10×10 -7 m / s; Preferably, during the diffusion dialysis treatment in step (1), the flow rate of the nickel-iron filtrate is 0.2 L / (m 2 ·h)~0.5L / (m 2 h); Preferably, during the diffusion dialysis treatment in step (1), the inlet flow ratio of the nickel-iron filtrate to the pure water is (1.2-2.2):1; Preferably, during the diffusion dialysis treatment in step (1), the inlet temperature of the nickel-iron filtrate and the pure water is 15°C to 30°C.

4. The comprehensive treatment method according to any one of claims 1 to 3, characterized in that: The weight removal method in step (1) includes resin weight removal; Preferably, the resin comprises a weight removal resin and / or a selective nickel and iron removal resin; Preferably, the concentration treatment in step (1) comprises electrodialysis concentration; Preferably, the voltage of the electrodialysis concentration is 65V to 75V; Preferably, the current of the electrodialysis concentration is 60A-75A.

5. The comprehensive treatment method according to any one of claims 1 to 4, characterized in that: Step (2) the second solid-liquid separation method includes any one of filter press, precision filtration or ultrafiltration or a combination of at least two thereof; Preferably, the mass concentration of sodium sulfate in the acidified filtrate in step (2) is 55 g / L to 130 g / L; Preferably, the mass concentration of ammonia nitrogen in the acidified filtrate in step (2) is 8 g / L to 12 g / L; Preferably, the total mass concentration of nickel, cobalt and manganese in the acidified filtrate of step (2) is 0.5 g / L to 2 g / L; Preferably, the carbon dioxide in step (2) is introduced into the dilute ammonium solution obtained in step (3) as a deammoniation receiving solution.

6. The comprehensive treatment method according to any one of claims 1 to 5, characterized in that: The secondary weight removal method in step (2) includes resin weight removal; Preferably, the resin comprises a weight removal resin and / or a selective nickel, cobalt and manganese removal resin.

7. The comprehensive treatment method according to any one of claims 1 to 6, characterized in that: The regulator for adjusting the pH of the secondary degravity liquid in step (3) comprises caustic soda flakes and / or liquid caustic soda; Preferably, the pH in step (3) is >10.

8. The comprehensive treatment method according to any one of claims 1 to 7, characterized in that: The secondary deweighting liquid is subjected to a heating treatment before the deamination treatment in step (3); Preferably, the deammoniation treatment in step (3) comprises passing the secondary deweighting liquid and the deammoniation receiving liquid into a deammoniation membrane; Preferably, the solute of the deamination receiving solution includes carbonic acid and ammonium bicarbonate; Preferably, the inlet temperature of the deamination treatment in step (3) is 30°C to 40°C; Preferably, during the deamination treatment in step (3), the circulation flow rates of the deamination receiving liquid and the secondary deweighting liquid are independently 8 m / s. 3 / (m 2 ·h)~10.5m 3 / (m 2 h); Preferably, during the deammoniation treatment in step (3), when the pH of the circulating liquid of the secondary deweighting liquid is less than 9, a deammoniation liquid is produced.

9. The comprehensive treatment method according to any one of claims 1 to 8, characterized in that: During the double displacement electrodialysis treatment in step (3), liquid alkali is added to adjust the pH; Preferably, the mass concentration of the liquid caustic soda is 3% to 30%; Preferably, the pH of the double displacement electrodialysis treatment in step (3) is >10.

10. The comprehensive treatment method according to any one of claims 1 to 9, characterized in that: The voltage of the double displacement electrodialysis treatment in step (3) is 10V to 30V; Preferably, the current density of the double replacement electrodialysis treatment in step (3) is 300 A / m 2 ~500A / m 2 ; Preferably, the current of the double displacement electrodialysis treatment in step (3) is 10A to 40A; Preferably, during the double displacement electrodialysis treatment in step (3), the end point is reached when the conductivity of the deammoniation liquid is less than 2 ms / cm.

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