Cyclic treatment process of tantalum-niobium wet smelting alkaline wastewater

Abstract

The invention provides a cyclic treatment process of tantalum-niobium wet smelting alkaline wastewater, and belongs to the technical field of tantalum-niobium wet smelting wastewater treatment.The low-fluorine pure water and ammonia-containing recycled water used in the treatment process are recycled wastewater of the tantalum-niobium wet smelting alkaline wastewater; the alkaline wastewater is recycled to the maximum extent, and the water consumption of new water in the alkaline wastewater treatment process can be greatly reduced; in the whole treatment process of the process, a small amount of chemically pure hydrofluoric acid is added, other chemical substances are not additionally added, no waste residues are discharged, the operation cost is remarkably reduced, the high-purity and high-value ammonium fluoride product can be produced, and the purity of the ammonium fluoride product can reach 98% or above. According to the treatment process disclosed by the invention, fluorine and ammonia in the wastewater can be effectively recycled through resource treatment, zero discharge of the tantalum-niobium wet smelting alkaline wastewater is basically realized, and the treated low-fluorine pure water meets first-grade standard requirements of a table 1 and a table 4 in Integrated Wastewater Discharge Standard (GB 8978-1996). According to the treatment process disclosed by the invention, the condensate water and the reuse water subjected to the multi-stage membrane concentration treatment are subjected to quality and retention treatment for reuse according to different ammonia nitrogen concentrations in the condensate water and the reuse water subjected to the multi-stage membrane concentration treatment, so that the dosage of ammonia and hydrofluoric acid can be greatly reduced, and the production cost is remarkably reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of tantalum-niobium hydrometallurgical wastewater treatment, and more specifically, relates to a circulation treatment process for tantalum-niobium hydrometallurgical alkaline wastewater. Background Art

[0002] During the hydrometallurgical process of tantalum and niobium, wastewater containing fluorine and ammonia nitrogen is the main wastewater, accounting for about 80-90% of the total wastewater. The main components of this part of wastewater are ammonium sulfate, ammonium fluoride and free ammonia, with a pH of 9-10, a fluorine content of 5-10g / L, and an ammonia nitrogen content of 10-20g / L. According to the national standard (GB8978-1996 Comprehensive Wastewater Discharge Standard), the ammonia nitrogen content of the first-level wastewater discharge is allowed to be less than 15mg / L, and the second-level discharge standard is less than 50mg / L; the fluorine content is 10mg / L in the first and second-level discharge standards, and 20mg / L in the third-level discharge standard. Therefore, wastewater containing fluorine and ammonia nitrogen must be treated before it can be discharged.

[0003] At present, the discharge of ammonia nitrogen and fluoride ions in the alkaline wastewater of the domestic tantalum-niobium hydrometallurgical industry will cause great pollution to the environment. The traditional treatment method is to add lime to the wastewater to produce insoluble calcium fluoride, remove suspended matter by plate and frame filtration or sand filter, and then treat the clear liquid by stripping. This process technology not only has high energy consumption, but also produces a large amount of general solid waste, which occupies a large amount of space for stacking, causing secondary pollution and becoming a bottleneck restricting the development of enterprises. Summary of the invention

[0004] The purpose of the present invention is to provide a recycling treatment process for alkaline wastewater from tantalum-niobium hydrometallurgy, so as to achieve no waste residue generation during the wastewater treatment process and the discharge of wastewater meets the standards, and at the same time, valuable by-products are extracted from the alkaline wastewater for sale, thereby turning waste into treasure, managing the environment, and utilizing wastewater as a resource, which has good economic and social benefits.

[0005] To achieve the above object, the present invention provides a recycling treatment process for alkaline wastewater from tantalum-niobium hydrometallurgy, comprising the following steps:

[0006] Recycling low-fluorine pure water is added to the fluoroniobic acid solution and the fluorotantalic acid solution for stripping to obtain high-purity niobium solution and high-purity tantalum solution;

[0007] The high-purity niobium liquid and the high-purity tantalum liquid are subjected to oil-water separation to remove the organic extractant, thereby obtaining deoiled high-purity niobium liquid and deoiled high-purity tantalum liquid;

[0008] Respectively adding ammonia-containing recycled water to the deoiled high-purity niobium liquid and the deoiled high-purity tantalum liquid, and obtaining mother liquor after neutralization, precipitation and filter pressing; and washing the filter residue with the ammonia-containing recycled water, and filtering again to obtain washing water, and drying and calcining the filter residue to obtain niobium oxide and tantalum oxide products;

[0009] The washing water and the mother liquor are respectively subjected to step-by-step precipitation and ceramic membrane filtration to obtain filtered washing water and filtered mother liquor;

[0010] The filtered wash water is subjected to multi-stage membrane concentration and reverse osmosis membrane concentration treatment to obtain the concentrated ammonia-containing recycling water and the low-fluorine pure water;

[0011] The concentrated ammonium fluoride water obtained by subjecting the filtered mother liquor and the filtered wash water to the multi-stage membrane concentration is preheated and concentrated by low-temperature vacuum evaporation to obtain a saturated ammonium fluoride solution and condensed water; chemically pure hydrofluoric acid is added to the condensed water to obtain an aqueous ammonium fluoride solution, and the aqueous ammonium fluoride solution is transferred to the multi-stage membrane concentration treatment to obtain the concentrated ammonium fluoride water and the low-fluorine pure water; the saturated ammonium fluoride solution is crystallized and centrifuged to obtain ammonium fluoride crystals.

[0012] Furthermore, during the stripping, the volume ratio of the low-fluorine pure water to the fluoroniobic acid solution is 0.3-0.8:1, and the acidity of the stripping system is 2.8-3.2 mol / L; the volume ratio of the low-fluorine pure water to the fluorotantalate solution is 0.3-0.8:1, and the acidity of the stripping system is 2.8-3.2 mol / L.

[0013] Furthermore, the oil-water separation separates and removes the upper organic extractant by a multi-stage precipitation method, the COD of the deoiled high-purity niobium liquid is 400-1000ppm, and the COD of the deoiled high-purity tantalum liquid is 600-1500ppm.

[0014] Furthermore, during the neutralization precipitation, the volume ratio of the ammonia-containing recycled water to the deoiled high-purity niobium liquid is 2-2.3:1, the volume ratio of the ammonia-containing recycled water to the deoiled high-purity tantalum liquid is 2.5-3:1, and the pH of the solution is 8.5-10.

[0015] Furthermore, the ceramic membrane is a silicon carbide ceramic membrane with a pore size of 100 nm.

[0016] Furthermore, the multi-stage membrane concentration is three-stage or four-stage concentration, the membranes used are ultrafiltration membrane, RO membrane and electrodialysis concentration membrane, and the concentration of ammonium fluoride in the ammonium fluoride concentrated water is 5-14wt%.

[0017] Furthermore, the concentration of ammonia nitrogen in the ammonia-containing circulating reuse water is 30,000-60,000 ppm.

[0018] Furthermore, the concentration of ammonia nitrogen in the condensed water is 5000-8000 ppm.

[0019] Furthermore, the COD of the washed water after filtration is 0-100 ppm, and the COD of the mother liquor after filtration is 200-300 ppm.

[0020] Furthermore, the temperature of the low-temperature vacuum evaporation concentration is 55-65°C and the pressure is -80 to -90 kPa.

[0021] Compared with the prior art, the present invention has the following technical effects:

[0022] The low-fluorine pure water and ammonia-containing recycled water used in the recycling treatment process of alkaline wastewater from tantalum-niobium hydrometallurgy of the present invention are both reused wastewater of alkaline wastewater from tantalum-niobium hydrometallurgy, so that the alkaline wastewater can be recycled and reused to the maximum extent, and the water consumption of new water in the alkaline wastewater treatment process can be greatly reduced; in the entire treatment process of the process of the present invention, except for adding a small amount of chemically pure hydrofluoric acid, no other chemical substances are added, and no waste residue is discharged, the operating cost is significantly reduced, and high-purity and high-value ammonium fluoride products can be produced, the purity of the ammonium fluoride product can reach more than 98%, and the quality index of the ammonium fluoride product can reach or even exceed the requirements of GB28653-2012 "Industrial Ammonium Fluoride".

[0023] The circulating treatment process of alkaline wastewater from tantalum-niobium hydrometallurgy of the present invention can effectively recycle fluorine and ammonia in the wastewater through resource management, and basically achieves zero discharge of alkaline wastewater from tantalum-niobium hydrometallurgy.

[0024] The circulating treatment process of alkaline wastewater from tantalum-niobium hydrometallurgy of the present invention reduces impurities in fluoroniobium (tantalate) acid solution by stripping with low-fluorine pure water and separating oil from water, thereby improving the purity of tantalum-niobium products; and further recovers tantalum-niobium impurities in the wastewater by step-by-step sedimentation and ceramic membrane filtration, while improving the quality of by-product ammonium fluoride, so that the purity of the prepared ammonium fluoride product can reach more than 98%.

[0025] In a recycling treatment process for alkaline wastewater from tantalum-niobium hydrometallurgy of the present invention, the wastewater is subjected to step-by-step sedimentation treatment before being filtered through a ceramic membrane, and the tantalum-niobium impurities in the wastewater are preliminarily separated and recovered, thereby reducing the content of suspended matter and fine particles such as tantalum-niobium impurities in the wastewater, and can effectively increase the service life of the ceramic membrane.

[0026] The recycling treatment process of tantalum-niobium hydrometallurgical alkaline wastewater of the present invention targets the difference in ammonia nitrogen concentration between condensed water and recycled water after multi-stage membrane concentration treatment, separates the condensed water and the recycled water after multi-stage membrane concentration treatment for quality and retention before reuse, that is, only chemically pure hydrofluoric acid is added to the condensed water with low ammonia nitrogen concentration, and the recycled water after multi-stage membrane concentration treatment with high ammonia nitrogen concentration is concentrated again through a reverse osmosis membrane and used as ammonia-containing recycling water in the neutralization precipitation step, which can greatly reduce the dosage of ammonia and hydrofluoric acid and significantly reduce production costs.

[0027] The low-fluorine pure water obtained by the circulating treatment process of alkaline wastewater from tantalum-niobium hydrometallurgy of the present invention meets the first-level standard requirements of Table 1 and Table 4 in the Comprehensive Wastewater Discharge Standard (GB 8978-1996). BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0029] Figure 1 , Figure 2 A process flow chart of a recycling treatment process for alkaline wastewater from tantalum-niobium hydrometallurgy provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0031] In the present invention, the term "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects before and after are in an "or" relationship.

[0032] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0033] The embodiment of the present invention provides a recycling treatment process for alkaline wastewater from tantalum-niobium hydrometallurgy, the process flow of which is as follows: Figure 1, Figure 2 As shown, the following steps are included:

[0034] (1) adding recycled low-fluorine pure water to the fluoroniobic acid solution and the fluorotantalic acid solution respectively for stripping to obtain high-purity niobium solution and high-purity tantalum solution;

[0035] (2) performing oil-water separation on the high-purity niobium liquid and the high-purity tantalum liquid to remove the organic extractant, thereby obtaining deoiled high-purity niobium liquid and deoiled high-purity tantalum liquid;

[0036] (3) adding recycled water containing ammonia to the deoiled high-purity niobium liquid and the deoiled high-purity tantalum liquid respectively, and obtaining mother liquor after neutralization, precipitation and filter pressing; washing the filter residue with the recycled water containing ammonia, and filtering again to obtain washing water; and drying and calcining the filter residue to obtain niobium oxide and tantalum oxide products;

[0037] (4) subjecting the wash water and the mother liquor to step-by-step precipitation and ceramic membrane filtration to obtain filtered wash water and filtered mother liquor respectively;

[0038] (5) subjecting the filtered wash water to multi-stage membrane concentration and reverse osmosis membrane concentration to obtain concentrated ammonia-containing recycling water and low-fluorine pure water;

[0039] (6) Preheating and concentrating the filtered mother liquor and the filtered wash water to obtain concentrated ammonium fluoride water, and then low-temperature vacuum evaporation and concentration to obtain a saturated ammonium fluoride solution and condensed water; adding chemically pure hydrofluoric acid to the condensed water to obtain an aqueous ammonium fluoride solution, and transferring the aqueous ammonium fluoride solution to a multi-stage membrane concentration process to obtain concentrated ammonium fluoride water and low-fluorine pure water; and crystallizing and centrifuging the saturated ammonium fluoride solution to obtain ammonium fluoride crystals.

[0040] In the above step (1), the fluoroniobate acid solution and the fluorotantalate acid solution come from the tantalum-niobium hydrometallurgical process, that is, the tantalum-niobium ore raw material is decomposed and leached with hydrofluoric acid and sulfuric acid, and the leached ore pulp is extracted with 2-octanol as an extractant. The extract is subjected to acid washing to remove impurities and de-niobium to obtain the fluoroniobate acid solution and the organic phase after de-niobium, and the organic phase after de-niobium is subjected to de-tantalization to obtain the fluorotantalate acid solution.

[0041] The niobium content (in terms of Nb2O5) in the fluoroniobate acid solution of the embodiment of the present invention is 230 g / L, the concentration of sulfate ions is 3 g / L, and the acidity is 3.1 mol / L; the tantalum content (in terms of Tb2O5) in the fluorotantalate solution is 100 g / L, the concentration of sulfate ions is 2 g / L, and the acidity is 2.1 mol / L.

[0042] In the embodiment of the present invention, recycled low-fluorine pure water is added to the fluoroniobic acid solution and the fluorotantalic acid solution for stripping, thereby reducing the sulfate ion concentration in the fluoroniobic (tantalic) acid solution and reducing the acidity of the acid solution, which is beneficial to the subsequent acquisition of a high-purity ammonium fluoride product.

[0043] In an embodiment of the present invention, during stripping, the volume ratio of low-fluorine pure water to fluoroniobic acid solution is 0.3-0.8:1, and the acidity of the stripping system is 2.8-3.2 mol / L; the volume ratio of low-fluorine pure water to fluorotantalate solution is 0.3-0.8:1, and the acidity of the stripping system is 2.8-3.2 mol / L.

[0044] In the above step (2), the oil-water separation of the embodiment of the present invention separates and removes the upper organic extractant 2-octanol by a multi-stage precipitation method. The COD of the deoiled high-purity niobium liquid obtained after oil-water separation is 400-1000ppm, and the COD of the deoiled high-purity tantalum liquid is 600-1500ppm. The presence of 2-octanol in the wastewater will affect the crystallization process of ammonium fluoride, thereby reducing the purity of ammonium fluoride. Therefore, the embodiment of the present invention removes 2-octanol in the wastewater by oil-water separation, which is beneficial to the subsequent acquisition of high-purity ammonium fluoride. The embodiment of the present invention combines the use of low-fluorine pure water stripping and oil-water separation processes to make the purity of the ammonium fluoride product reach more than 98%.

[0045] In the above step (3), the concentration of ammonia nitrogen in the ammonia-containing recycled water of the embodiment of the present invention is 30000-60000 ppm. During neutralization precipitation, the volume ratio of the ammonia-containing recycled water to the deoiled high-purity niobium liquid is 2-2.3:1, the volume ratio of the ammonia-containing recycled water to the deoiled high-purity tantalum liquid is 2.5-3:1, and the pH of the solution is 8.5-10. After neutralization precipitation and filter pressing, the mother liquor is obtained, and the filter residue is also washed with the ammonia-containing recycled water and filtered to obtain wash water. The filter residue after the filter pressing is dried to obtain niobium hydroxide and tantalum hydroxide, and then high-purity niobium oxide and tantalum oxide products are obtained after calcination, screening, batch mixing and packaging.

[0046] In the above step (4), the embodiment of the present invention precipitates or filters a small amount of insoluble niobium hydroxide and tantalum hydroxide in the wash water and mother liquor by gradual precipitation and ceramic membrane filtration, and recovers niobium hydroxide or tantalum hydroxide impurities by filter pressing. The ceramic membrane of the embodiment of the present invention is a silicon carbide ceramic membrane with a pore size of 100nm. The COD of the wash water after filtration is 0-100ppm, and the COD of the mother liquor after filtration is 200-300ppm.

[0047] The embodiment of the present invention combines oil-water separation, step-by-step sedimentation and ceramic membrane filtration processes to reduce the COD in the mother liquor from 2500ppm in the conventional process to 200-300ppm, and reduce the COD in the wash water from 1500ppm in the conventional process to below 100ppm.

[0048] In the above steps (5) and (6), the multi-stage membrane concentration of the embodiment of the present invention is three-stage or four-stage concentration, and the membranes used in the multi-stage membrane concentration are ultrafiltration membrane, RO membrane and electrodialysis concentration membrane in sequence, wherein the ultrafiltration membrane element is PVDF, and the water treatment volume is 10-20m 3 / h; RO membrane is a polyamide composite membrane, operating pressure 20 ~ 70bar; electrodialysis concentration membrane treatment of the total amount of salt migration is 150-160kg / h. Reverse osmosis membrane material is aromatic polyhydrazide membrane, filtration pressure 0.8-1.0MPa, through the reverse osmosis membrane concentrated to 60-80% of the original volume.

[0049] The washed water after filtration is concentrated by multi-stage membrane to obtain ammonium fluoride concentrated water and recycled water after multi-stage membrane concentration treatment. The recycled water after multi-stage membrane concentration treatment is concentrated again by reverse osmosis membrane to obtain concentrated ammonia-containing circulating recycled water (i.e. low-concentration ammonia water) and low-fluorine pure water (i.e. qualified water, which refers to water that meets the discharge index). The concentration of ammonium fluoride in the ammonium fluoride concentrated water is 5-14wt%.

[0050] In the embodiment of the present invention, the filtered mother liquor and ammonium fluoride concentrated water enter the preheater to be preheated to 50-60°C, and then enter the evaporation system for low-temperature vacuum evaporation and concentration to obtain condensed water and ammonium fluoride saturated solution, the temperature of low-temperature vacuum evaporation and concentration is 55-65°C, and the pressure is -0.8 to -0.9 kpa. The concentration of ammonia nitrogen in the condensed water is 5000-8000 ppm.

[0051] According to an embodiment of the present invention, a recycling treatment process for alkaline wastewater from tantalum-niobium hydrometallurgy is carried out, in view of the different ammonia nitrogen concentrations in condensed water and the recycled water after multi-stage membrane concentration treatment, the condensed water and the recycled water after multi-stage membrane concentration treatment are separated by quality and retained for reuse, that is, only chemically pure hydrofluoric acid is added to the condensed water with low ammonia nitrogen concentration, and the recycled water after multi-stage membrane concentration treatment with high ammonia nitrogen concentration is concentrated again through a reverse osmosis membrane and used as ammonia-containing circulating recycled water in the neutralization and precipitation step, which can greatly reduce the dosage of ammonia and hydrofluoric acid and significantly reduce production costs.

[0052] The low-fluorine pure water and ammonia-containing recycled water used in the recycling treatment process of alkaline wastewater from tantalum-niobium hydrometallurgy in the embodiment of the present invention are both reused wastewater of alkaline wastewater from tantalum-niobium hydrometallurgy, so that the alkaline wastewater can be recycled and reused to the maximum extent, which can greatly reduce the water consumption of new water in the alkaline wastewater treatment process; in the entire treatment process of the process of the embodiment of the present invention, except for a small amount of chemically pure hydrofluoric acid, no other chemical substances are added, and no waste residue is discharged, the operating cost is significantly reduced, and high-purity and high-value ammonium fluoride products can be produced, the purity of the ammonium fluoride product can reach more than 98%, and the quality index of the ammonium fluoride product can reach or even exceed the requirements of GB28653-2012 "Industrial Ammonium Fluoride". The low-fluorine pure water in the embodiment of the present invention meets the first-level standard requirements of Table 1 and Table 4 in the "Comprehensive Wastewater Discharge Standard" (GB 8978-1996).

[0053] The following two specific embodiments are used to illustrate a recycling treatment process for alkaline wastewater from tantalum-niobium hydrometallurgy according to an embodiment of the present invention.

[0054] Example 1

[0055] Embodiment 1 of the present invention provides a recycling treatment process for alkaline wastewater from tantalum-niobium hydrometallurgy, comprising the following steps:

[0056] (1) Recycled low-fluorine pure water is added to the fluoroniobic acid solution and the fluorotantalic acid solution for stripping to obtain high-purity niobium solution and high-purity tantalum solution; wherein the niobium content (in terms of Nb2O5) in the fluoroniobic acid solution is 230 g / L, the concentration of sulfate ions is 3 g / L, and the acidity is 5 mol / L; the tantalum content (in terms of Tb2O5) in the fluorotantalic acid solution is 100 g / L, the concentration of sulfate ions is 2 g / L, and the acidity is 4 mol / L. The volume ratio of low-fluorine pure water to the fluoroniobic acid solution is 0.5:1, and the acidity of the stripping system is 2.9 mol / L; the volume ratio of low-fluorine pure water to the fluorotantalic acid solution is 0.5:1, and the acidity of the stripping system is 3.1 mol / L.

[0057] (2) separating the high-purity niobium liquid and the high-purity tantalum liquid from oil and water to remove the octanol, thereby obtaining a deoiled high-purity niobium liquid and a deoiled high-purity tantalum liquid; the COD of the deoiled high-purity niobium liquid is 800 ppm, and the COD of the deoiled high-purity tantalum liquid is 1200 ppm;

[0058] (3) adding ammonia-containing recycled water with an ammonia nitrogen concentration of 36000 ppm to the deoiled high-purity niobium liquid and the deoiled high-purity tantalum liquid respectively, and obtaining mother liquor after neutralization, precipitation and filter pressing; washing the filter residue with the ammonia-containing recycled water, and filtering again to obtain washing water, and drying and calcining the filter residue to obtain niobium oxide and tantalum oxide products; the volume ratio of the added ammonia-containing recycled water to the deoiled high-purity niobium liquid is 2:1, and the volume ratio of the added ammonia-containing recycled water to the deoiled high-purity tantalum liquid is 2.5:1. During the neutralization and precipitation, the pH of the solution is 8.5-10.

[0059] (4) The wash water and the mother liquor are respectively subjected to step-by-step sedimentation and silicon carbide ceramic membrane filtration to obtain filtered wash water and filtered mother liquor; the COD of the filtered wash water is 80 ppm, and the COD of the filtered mother liquor is 220 ppm.

[0060] (5) The washed water after filtration is concentrated by an ultrafiltration membrane, an RO membrane and an electrodialysis concentration membrane in sequence, and finally concentrated by a reverse osmosis membrane to obtain concentrated ammonia-containing recycling water and low-fluorine pure water;

[0061] (6) The mother liquor and the washing water after filtration are concentrated by multi-stage membrane to obtain concentrated ammonium fluoride water with a concentration of 5-6wt%, which is preheated to 50-55°C. The concentration of ammonium fluoride in the concentrated ammonium fluoride water is 8-14wt%. After that, low-temperature vacuum evaporation and concentration are carried out at 55-65°C and a pressure of -80 to -85kPa to obtain a saturated ammonium fluoride solution and condensed water. The concentration of ammonia nitrogen in the condensed water is 6000ppm. Add stoichiometric chemically pure hydrofluoric acid to the condensed water to obtain an ammonium fluoride aqueous solution. When the solution is neutral, stop adding hydrofluoric acid. Transfer the ammonium fluoride aqueous solution to a three-stage membrane concentration process for the next batch of production to obtain ammonium fluoride concentrated water and low-fluorine pure water; crystallize the saturated ammonium fluoride solution and centrifuge to obtain ammonium fluoride crystals with a purity of 98%. The aqueous solution produced after centrifugation enters the preheater as ammonium fluoride concentrated water for the next batch of production.

[0062] Example 2

[0063] Embodiment 1 of the present invention provides a recycling treatment process for alkaline wastewater from tantalum-niobium hydrometallurgy, comprising the following steps:

[0064] (1) Recycled low-fluorine pure water is added to the fluoroniobic acid solution and the fluorotantalic acid solution for stripping to obtain high-purity niobium solution and high-purity tantalum solution; wherein the niobium content (in terms of Nb2O5) in the fluoroniobic acid solution is 230 g / L, the concentration of sulfate ions is 3 g / L, and the acidity is 5 mol / L; the tantalum content (in terms of Tb2O5) in the fluorotantalic acid solution is 100 g / L, the concentration of sulfate ions is 2 g / L, and the acidity is 4 mol / L. The volume ratio of low-fluorine pure water to the fluoroniobic acid solution is 0.8:1, and the acidity of the stripping system is 2.8 mol / L; the volume ratio of low-fluorine pure water to the fluorotantalic acid solution is 0.6:1, and the acidity of the stripping system is 2.9 mol / L.

[0065] (2) separating the high-purity niobium liquid and the high-purity tantalum liquid from oil and water to remove the octanol, thereby obtaining a deoiled high-purity niobium liquid and a deoiled high-purity tantalum liquid; the COD of the deoiled high-purity niobium liquid is 600 ppm, and the COD of the deoiled high-purity tantalum liquid is 900 ppm;

[0066] (3) adding ammonia-containing recycled water with an ammonia nitrogen concentration of 45,000 ppm to the deoiled high-purity niobium liquid and the deoiled high-purity tantalum liquid respectively, and obtaining mother liquor after neutralization, precipitation and filter pressing; washing the filter residue with the ammonia-containing recycled water, and filtering again to obtain washing water, and drying and calcining the filter residue to obtain niobium oxide and tantalum oxide products; the volume ratio of the added ammonia-containing recycled water to the deoiled high-purity niobium liquid is 2.2:1, and the volume ratio of the added ammonia-containing recycled water to the deoiled high-purity tantalum liquid is 3:1. During the neutralization and precipitation, the pH of the solution is 8.5-10.

[0067] (4) The wash water and the mother liquor are respectively subjected to step-by-step sedimentation and silicon carbide ceramic membrane filtration to obtain filtered wash water and filtered mother liquor; the COD of the filtered wash water is 60 ppm, and the COD of the filtered mother liquor is 260 ppm.

[0068] (5) The washed water after filtration is concentrated by an ultrafiltration membrane, an RO membrane and an electrodialysis concentration membrane in sequence, and finally concentrated by a reverse osmosis membrane to obtain concentrated ammonia-containing recycling water and low-fluorine pure water;

[0069] (6) The mother liquor and the washing water after filtration are concentrated by multi-stage membrane to obtain concentrated ammonium fluoride water with a concentration of 5-6wt%, which is preheated to 50-55°C, and the concentration of ammonium fluoride in the concentrated ammonium fluoride water is 8-14wt%. After that, low-temperature vacuum evaporation and concentration are carried out at 63-65°C and a pressure of -85 to -90kPa to obtain a saturated ammonium fluoride solution and condensed water, and the concentration of ammonia nitrogen in the condensed water is 5000ppm. Add stoichiometric chemically pure hydrofluoric acid to the condensed water to obtain an ammonium fluoride aqueous solution. When the solution is neutral, stop adding hydrofluoric acid, and transfer the ammonium fluoride aqueous solution to a three-stage membrane concentration process for the next batch of production to obtain ammonium fluoride concentrated water and low-fluorine pure water; the saturated ammonium fluoride solution is crystallized and centrifuged to obtain ammonium fluoride crystals with a purity of 96%. The aqueous solution produced after centrifugation enters the preheater as ammonium fluoride concentrated water for the next batch of production.

[0070] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the attached claims.

Claims

1. A recycling process for treating alkaline wastewater from tantalum-niobium hydrometallurgy, characterized in that: The following steps are involved: Recycling low-fluorine pure water is added to the fluoroniobate acid solution and the fluorotantalate acid solution for stripping to obtain high-purity niobium solution and high-purity tantalum solution; The high-purity niobium liquid and the high-purity tantalum liquid are subjected to oil-water separation to remove the organic extractant, thereby obtaining deoiled high-purity niobium liquid and deoiled high-purity tantalum liquid; Adding recycled water containing ammonia to the deoiled high-purity niobium liquid and the deoiled high-purity tantalum liquid respectively, and obtaining mother liquor after neutralization, precipitation and pressure filtration; The filter residue is washed with the ammonia-containing recycled water, and filtered again to obtain washing water, and the filter residue is dried and calcined to obtain niobium oxide and tantalum oxide products; The washing water and the mother liquor are respectively subjected to step-by-step precipitation and ceramic membrane filtration to obtain filtered washing water and filtered mother liquor; The filtered wash water is subjected to multi-stage membrane concentration and reverse osmosis membrane concentration treatment to obtain the concentrated ammonia-containing recycling water and the low-fluorine pure water; The concentrated ammonium fluoride water obtained by subjecting the filtered mother liquor and the filtered wash water to the multi-stage membrane concentration is preheated and concentrated by low-temperature vacuum evaporation to obtain a saturated ammonium fluoride solution and condensed water; chemically pure hydrofluoric acid is added to the condensed water to obtain an aqueous ammonium fluoride solution, and the aqueous ammonium fluoride solution is transferred to the multi-stage membrane concentration treatment to obtain the concentrated ammonium fluoride water and the low-fluorine pure water; the saturated ammonium fluoride solution is crystallized and centrifuged to obtain ammonium fluoride crystals.

2. The recycling treatment process of alkaline wastewater from tantalum-niobium hydrometallurgy as claimed in claim 1, characterized in that: During the stripping, the volume ratio of the low-fluorine pure water to the fluoroniobic acid solution is 0.3-0.8:1, and the acidity of the stripping system is 2.8-3.2 mol / L; the volume ratio of the low-fluorine pure water to the fluorotantalate solution is 0.3-0.8:1, and the acidity of the stripping system is 2.8-3.2 mol / L.

3. The recycling treatment process of alkaline wastewater from tantalum-niobium hydrometallurgy as claimed in claim 1, characterized in that: The oil-water separation separates and removes the upper organic extractant by a multi-stage precipitation method. The COD of the deoiled high-purity niobium liquid is 400-1000ppm, and the COD of the deoiled high-purity tantalum liquid is 600-1500ppm.

4. The recycling treatment process for alkaline wastewater from tantalum-niobium hydrometallurgy as claimed in claim 1, characterized in that: During the neutralization precipitation, the volume ratio of the ammonia-containing recycled water to the deoiled high-purity niobium liquid is 2-2.3:1, the volume ratio of the ammonia-containing recycled water to the deoiled high-purity tantalum liquid is 2.5-3:1, and the pH of the solution is 8.5-10.

5. The recycling treatment process of alkaline wastewater from tantalum-niobium hydrometallurgy as claimed in claim 1, characterized in that: The ceramic membrane is a silicon carbide ceramic membrane with a pore size of 100 nm.

6. The recycling treatment process for alkaline wastewater from tantalum-niobium hydrometallurgy as claimed in claim 1, characterized in that: The multi-stage membrane concentration is three-stage or four-stage concentration, and the membranes used are ultrafiltration membrane, RO membrane and electrodialysis concentration membrane. The concentration of ammonium fluoride in the ammonium fluoride concentrated water is 5-14wt%.

7. The recycling treatment process for alkaline wastewater from tantalum-niobium hydrometallurgy as claimed in claim 1, characterized in that: The concentration of ammonia nitrogen in the ammonia-containing circulating reuse water is 30,000-60,000 ppm.

8. The recycling treatment process for alkaline wastewater from tantalum-niobium hydrometallurgy as claimed in claim 1, characterized in that: The concentration of ammonia nitrogen in the condensed water is 5000-8000 ppm.

9. The recycling treatment process for alkaline wastewater from tantalum-niobium hydrometallurgy as claimed in claim 1, characterized in that: The COD of the washed water after filtration is 0-100 ppm, and the COD of the mother liquor after filtration is 200-300 ppm.

10. A circulating treatment process for alkaline wastewater from tantalum-niobium hydrometallurgy as claimed in any one of claims 1 to 9, characterized in that: The temperature of the low-temperature vacuum evaporation concentration is 55-65°C and the pressure is -80 to -90 kPa.

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