A recycling treatment process for tantalum-niobium wet smelting alkaline wastewater

Abstract

The application provides a recycling treatment process for 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 the ammonia-containing recycling water used in the treatment process are both reused wastewater of the tantalum-niobium wet smelting alkaline wastewater, so that the alkaline wastewater can be 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 application, a small amount of chemical pure hydrofluoric acid is added, and no other chemicals are additionally added, and no waste residue is discharged, so that the operation cost is significantly reduced, and a high-purity high-value ammonium fluoride product can be produced, and the purity of the ammonium fluoride product can reach more than 98%. The treatment process of the application can effectively recycle and utilize the fluorine and ammonia in the wastewater through resource management, basically realizes zero discharge of the tantalum-niobium wet smelting alkaline wastewater, and the low-fluorine pure water after treatment meets the first standard requirement of Table 1 and Table 4 in the Integrated Wastewater Discharge Standard (GB 8978-1996). The treatment process of the application is aimed at the different ammonia nitrogen concentrations in the condensate water and the recycling water after multi-stage membrane concentration treatment, and the condensate water and the recycling water after multi-stage membrane concentration treatment are treated and reused after being separated according to quality, so that the dosing amount of ammonia and hydrofluoric acid can be greatly reduced, and the production cost can be significantly reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of treating wastewater in tantalum-niobium hydrometallurgy, and more particularly relates to a recycling treatment process for alkaline wastewater in tantalum-niobium hydrometallurgy. BACKGROUND

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

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

[0004] The purpose of the present application is to provide a recycling treatment process for alkaline wastewater in tantalum-niobium hydrometallurgy, so as to realize no waste residue generation in the wastewater treatment process, wastewater discharge reaching the standard, and extraction of valuable by-products from the alkaline wastewater for sale, realizing waste-to-resource, environmental governance, and wastewater resource utilization, and having good economic and social benefits.

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

[0006] Low-fluorine pure water recycled is added to fluoroniobate solution and fluorotantalate solution respectively for back extraction, to obtain high-purity niobium liquid and high-purity tantalum liquid;

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

[0008] The ammonia-containing recycled water is added into the oil-removed high-purity niobium liquid and the oil-removed high-purity tantalum liquid respectively, and mother liquor is obtained after neutralization precipitation and pressure filtration; and the filter residue is washed with the ammonia-containing recycled water and then pressure filtered again to obtain washing water, and the filter residue is dried and calcined to obtain niobium oxide and tantalum oxide products;

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

[0010] The filtered washing water is subjected to multi-stage membrane concentration and reverse osmosis membrane concentration treatment to obtain concentrated ammonia-containing recycled water and low-fluorine pure water.

[0011] The ammonium fluoride concentrated water obtained by the multi-stage membrane concentration of the filtered mother liquor and the filtered washing water is subjected to preheating and low-temperature vacuum evaporation concentration to obtain an ammonium fluoride saturated solution and condensate water; chemical pure hydrofluoric acid is added into the condensate water to obtain an ammonium fluoride aqueous solution, which is transferred into the multi-stage membrane concentration treatment to obtain the ammonium fluoride concentrated water and the low-fluorine pure water; and the ammonium fluoride saturated solution is subjected to crystallization and centrifugal separation to obtain ammonium fluoride crystals.

[0012] Further, the volume ratio of the low-fluorine pure water to the fluoroniobate solution is 0.3-0.8:1, and the acidity of the stripping system is 2.8-3.2 mol / L; and 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] Further, the oil-water separation is achieved by removing the upper organic extractant through multi-stage precipitation, and the COD of the oil-removed high-purity niobium liquid is 400-1000 ppm, and the COD of the oil-removed high-purity tantalum liquid is 600-1500 ppm.

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

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

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

[0017] Further, the concentration of ammonia nitrogen in the ammonia-containing recycled water is 30000-60000 ppm.

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

[0019] Further, the COD of the filtered washing water is 0-100 ppm, and the COD of the filtered mother liquor is 200-300 ppm.

[0020] Further, the temperature of the low-temperature vacuum evaporation concentration is 55-65 DEG C, and the pressure is -80 to -90 kpa.

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

[0022] The low-fluorine pure water and the ammonia-containing recycled water used in the process of the present application are both reused wastewater of the tantalum-niobium wet smelting alkaline wastewater, so that the alkaline wastewater is maximally recycled and reused, and the water consumption of new water in the alkaline wastewater treatment process can be greatly reduced; in the entire treatment process of the present application, only a small amount of chemical pure hydrofluoric acid is added, no other chemicals are additionally added, no waste residue is discharged, the operating cost is significantly reduced, and a high-purity high-value ammonium fluoride product 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 process of the present application can effectively recycle and utilize the fluorine and ammonia in the wastewater through resource management, and basically realizes zero discharge of the tantalum-niobium wet smelting alkaline wastewater.

[0024] The process of the present application can reduce impurities in the fluoroniobate (tantalate) solution through low-fluorine pure water back extraction and oil-water separation, and improve the purity of tantalum-niobium products; and further through step-by-step bottom precipitation and ceramic membrane filtration, the tantalum-niobium impurities in the wastewater are recovered, and the quality of the byproduct ammonium fluoride is improved, so that the purity of the prepared ammonium fluoride product can reach more than 98%.

[0025] The process of the present application can reduce impurities in the fluoroniobate (tantalate) solution through low-fluorine pure water back extraction and oil-water separation, and improve the purity of tantalum-niobium products; and further through step-by-step bottom precipitation and ceramic membrane filtration, the tantalum-niobium impurities in the wastewater are recovered, and the quality of the byproduct ammonium fluoride is improved, so that the purity of the prepared ammonium fluoride product can reach more than 98%.

[0026] The recycling treatment process of the tantalum-niobium hydrometallurgy alkaline wastewater of the application can greatly reduce the dosing amount of ammonia and hydrofluoric acid, and significantly reduce the production cost.

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

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the application, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0029] Figure 1 、 Figure 2 The process flow chart of the recycling treatment process of the tantalum-niobium hydrometallurgy alkaline wastewater provided by the embodiments of the application is shown in the figure. DETAILED DESCRIPTION

[0030] In order to make the technical problems, technical solutions and beneficial effects to be solved by the application more clear, the application will be further described in detail in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the application, and are not used to limit the application.

[0031] In the application, the term "and / or" describes the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B, which can represent the following cases: A exists alone, A and B exist together, and B exists alone. Wherein A and B can be singular or plural. The character " / " generally represents that the associated objects before and after it are in an "or" relationship.

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

[0033] The embodiments of the application provide a recycling treatment process of tantalum-niobium hydrometallurgy alkaline wastewater, and the process flow is as shown in the figure. Figure 1、 Figure 2 As shown, comprising the following steps:

[0034] (1) respectively adding recycled low-fluorine pure water to fluoroniobate solution and fluorotantalate solution for back extraction to obtain high-purity niobium solution and high-purity tantalum solution;

[0035] (2) oil-water separation is performed on the high-purity niobium solution and the high-purity tantalum solution to remove organic extractant to obtain oil-removed high-purity niobium solution and oil-removed high-purity tantalum solution;

[0036] (3) adding ammonia-containing recycled water to the oil-removed high-purity niobium solution and the oil-removed high-purity tantalum solution respectively, after neutralization precipitation and pressure filtration, mother liquor is obtained; and the filter residue is washed with ammonia-containing recycled water, and after pressure filtration again, washing water is obtained, and the filter residue is dried and calcined to obtain niobium oxide and tantalum oxide products;

[0037] (4) the washing water and the mother liquor are sequentially subjected to step-by-step precipitation and ceramic membrane filtration to obtain filtered washing water and filtered mother liquor;

[0038] (5) the filtered washing water is subjected to multi-stage membrane concentration and reverse osmosis membrane concentration treatment to obtain concentrated ammonia-containing recycled water and low-fluorine pure water;

[0039] (6) the ammonium fluoride concentrated water obtained by multi-stage membrane concentration of the filtered mother liquor and the filtered washing water is subjected to preheating and low-temperature vacuum evaporation concentration to obtain ammonium fluoride saturated solution and condensate water; chemical pure hydrofluoric acid is added to the condensate water to obtain ammonium fluoride aqueous solution, and the ammonium fluoride aqueous solution is transferred to multi-stage membrane concentration treatment to obtain ammonium fluoride concentrated water and low-fluorine pure water; the ammonium fluoride saturated solution is subjected to crystallization and centrifugal separation to obtain ammonium fluoride crystals.

[0040] In the above step (1), the fluoroniobate solution and the fluorotantalate solution come from the tantalum-niobium hydrometallurgy process, that is, the tantalum-niobium ore raw material is decomposed and leached with hydrofluoric acid and sulfuric acid, and the leached slurry is extracted with octanol as an extractant, and after acid washing and niobium back extraction, the fluoroniobate solution and the organic phase after niobium back extraction are obtained, and after tantalum back extraction, the fluorotantalate solution is obtained.

[0041] The niobium content (calculated as Nb2O5) in the fluoroniobate solution of the embodiment of the present application is 230 g / L, the concentration of sulfate ions is 3 g / L, and the acidity is 3.1 mol / L; the tantalum content (calculated as 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 above step (1), the fluoroniobate solution and the fluorotantalate solution come from the tantalum-niobium hydrometallurgy process, that is, the tantalum-niobium ore raw material is decomposed and leached with hydrofluoric acid and sulfuric acid, and the leached slurry is extracted with octanol as an extractant, and after acid washing and niobium back extraction, the fluoroniobate solution and the organic phase after niobium back extraction are obtained, and after tantalum back extraction, the fluorotantalate solution is obtained.

[0043] In the embodiment of the present application, the volume ratio of low-fluorine pure water to fluoroniobate 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 step (2) above, the oil-water separation of the embodiment of the present application separates and removes the upper organic extractant sec-octanol by the method of multi-stage precipitation, and the COD of the de-oiled high-purity niobium liquid obtained after the oil-water separation is 400-1000 ppm, and the COD of the de-oiled high-purity tantalum liquid is 600-1500 ppm. The presence of sec-octanol in the wastewater will affect the crystallization process of ammonium fluoride, and thus the purity of ammonium fluoride is reduced. Therefore, the embodiment of the present application removes sec-octanol in the wastewater by oil-water separation, which is beneficial to obtaining high-purity ammonium fluoride subsequently. The embodiment of the present application combines the low-fluorine pure water stripping and the oil-water separation process, so that the purity of ammonium fluoride product can reach more than 98%.

[0045] In the step (3) above, the concentration of ammonia nitrogen in the ammonia-containing recycling water of the embodiment of the present application is 30000-60000 ppm. In the neutralization and precipitation, the volume ratio of the ammonia-containing recycling water to the de-oiled high-purity niobium liquid is 2-2.3:1, the volume ratio of the ammonia-containing recycling water to the de-oiled high-purity tantalum liquid is 2.5-3:1, and the pH of the solution is 8.5-10. After the neutralization and precipitation and the pressure filtration, the mother liquor is obtained, and the filter residue is also washed with the ammonia-containing recycling water, and then the pressure filtration is performed to obtain washing water. The filter residue after the pressure filtration is dried to obtain niobium hydroxide and tantalum hydroxide, which are then calcined, sieved, mixed, and packaged to obtain high-purity niobium oxide and tantalum oxide products.

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

[0047] The embodiment of the present application combines the oil-water separation, the step-by-step precipitation, and the ceramic membrane filtration process, so that the COD of the mother liquor can be reduced from 2500 ppm in the conventional process to 200-300 ppm, and the COD of the washing water can be reduced from 1500 ppm in the conventional process to less than 100 ppm.

[0048] In the steps (5) and (6), the multi-stage membrane concentration of the embodiment of the present application 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, the water treatment capacity is 10-20 m 3 / h; the RO membrane is a polyamide composite membrane, and the operating pressure is 20-70 bar; the total amount of salt migrated by the electrodialysis concentration membrane is 150-160 kg / h. The reverse osmosis membrane is an aromatic polyhydrazide membrane, and the filtration pressure is 0.8-1.0 MPa. The water is concentrated to 60-80% of the original volume by the reverse osmosis membrane.

[0049] After the filtered washing water is concentrated by the multi-stage membrane, ammonium fluoride concentrated water and reused water treated by the multi-stage membrane concentration are obtained. The reused water treated by the multi-stage membrane concentration is concentrated again by the reverse osmosis membrane to obtain concentrated ammonia-containing recycled water (i.e. low-concentration ammonia water) and low-fluorine pure water (i.e. qualified water, which refers to water meeting the discharge index). The concentration of ammonium fluoride in the ammonium fluoride concentrated water is 5-14 wt%.

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

[0051] The recycling treatment process for the alkaline wastewater of tantalum and niobium hydrometallurgy of the embodiment of the present application aims at the different concentrations of ammonia nitrogen in the condensed water and the reused water treated by the multi-stage membrane concentration. The condensed water and the reused water treated by the multi-stage membrane concentration are treated by quality separation and retention for reuse, i.e. only the condensed water with low ammonia nitrogen concentration is added with chemical pure hydrofluoric acid, and the reused water treated by the multi-stage membrane concentration with high ammonia nitrogen concentration is concentrated again by the reverse osmosis membrane and used as ammonia-containing recycled water in the neutralization and precipitation step. This can greatly reduce the dosages of ammonia and hydrofluoric acid and significantly reduce the production cost.

[0052] The low-fluorine pure water and the ammonia-containing recycled water used in the recycling treatment process of the tantalum-niobium wet smelting alkaline wastewater are both reused wastewater of the tantalum-niobium wet smelting alkaline wastewater, so that the alkaline wastewater is maximally recycled and reused, 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 chemical pure hydrofluoric acid is added, and no other chemicals are additionally added, and no waste residue is discharged, so that the operation cost is significantly reduced, and a high-purity high-value ammonium fluoride product 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 reaches the first standard requirements of Table 1 and Table 4 in the Comprehensive Wastewater Discharge Standard (GB 8978-1996).

[0053] The recycling treatment process of the tantalum-niobium wet smelting alkaline wastewater according to the embodiment of the present application is exemplified by two specific embodiments.

[0054] Embodiment 1

[0055] The embodiment 1 of the present application provides a recycling treatment process of tantalum-niobium wet smelting alkaline wastewater, comprising the following steps:

[0056] (1) adding the recycled low-fluorine pure water into the fluoroniobate solution and the fluorotantalate solution respectively for stripping to obtain high-purity niobium liquid and high-purity tantalum liquid; wherein the niobium content (calculated as Nb2O5) in the fluoroniobate solution is 230 g / L, the concentration of sulfate ions is 3 g / L, and the acidity is 5 mol / L; the tantalum content (calculated as Tb2O5) in the fluorotantalate 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 the low-fluorine pure water to the fluoroniobate solution is 0.5:1, and the acidity of the stripping system is 2.9 mol / L; the volume ratio of the low-fluorine pure water to the fluorotantalate solution is 0.5:1, and the acidity of the stripping system is 3.1 mol / L.

[0057] (2) performing oil-water separation on the high-purity niobium liquid and the high-purity tantalum liquid to remove secondary octanol to obtain oil-removed high-purity niobium liquid and oil-removed high-purity tantalum liquid; the COD of the oil-removed high-purity niobium liquid is 800 ppm, and the COD of the oil-removed high-purity tantalum liquid is 1200 ppm;

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

[0059] (4) sequentially performing step-by-step precipitation and silicon carbide ceramic membrane filtration on the washing water and the mother liquor respectively to obtain filtered washing water and filtered mother liquor; the COD of the filtered washing water is 80ppm, and the COD of the filtered mother liquor is 220ppm.

[0060] (5) sequentially performing ultrafiltration membrane, RO membrane and electrodialysis concentration membrane concentration on the filtered washing water, and finally performing reverse osmosis membrane concentration treatment to obtain concentrated ammonia-containing recycled water and low-fluorine pure water.

[0061] (6) obtaining the ammonium fluoride concentrated water with a concentration of 5-6wt% by performing multi-stage membrane concentration on the filtered mother liquor and the filtered washing water, preheating the ammonium fluoride concentrated water to 50-55℃, and the concentration of ammonium fluoride in the ammonium fluoride concentrated water being 8-14wt%; then performing low-temperature vacuum evaporation concentration at 55-65℃ and under a pressure of-80 to-85kpa to obtain ammonium fluoride saturated solution and condensate water, and the concentration of ammonia-nitrogen in the condensate water being 6000ppm; adding stoichiometric chemical pure hydrofluoric acid into the condensate water to obtain ammonium fluoride aqueous solution, and stopping adding the hydrofluoric acid when the solution is neutral, and transferring the ammonium fluoride aqueous solution into a three-stage membrane concentration treatment for next batch production to obtain ammonium fluoride concentrated water and low-fluorine pure water; obtaining ammonium fluoride crystals with a purity of 98% by performing crystallization and centrifugal separation on the ammonium fluoride saturated solution; and the aqueous solution produced after centrifugation is used as the ammonium fluoride concentrated water into a preheater for next batch production.

[0062] Example 2

[0063] The example 1 of the present application provides a recycling treatment process for tantalum-niobium wet smelting alkaline wastewater, comprising the following steps:

[0064] (1) adding recycled low-fluorine pure water to fluoroniobate solution and fluorotantalate solution respectively to perform back extraction, to obtain high-purity niobium solution and high-purity tantalum solution; wherein, the niobium content (calculated as Nb2O5) in the fluoroniobate solution is 230 g / L, the concentration of sulfate ions is 3 g / L, and the acidity is 5 mol / L; the tantalum content (calculated as Tb2O5) in the fluorotantalate 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 fluoroniobate solution is 0.8:1, and the acidity of the back extraction system is 2.8 mol / L; the volume ratio of low-fluorine pure water to fluorotantalate solution is 0.6:1, and the acidity of the back extraction system is 2.9 mol / L.

[0065] (2) performing oil-water separation on the high-purity niobium solution and the high-purity tantalum solution to remove secondary octanol, to obtain oil-removed high-purity niobium solution and oil-removed high-purity tantalum solution; the COD of the oil-removed high-purity niobium solution is 600 ppm, and the COD of the oil-removed high-purity tantalum solution is 900 ppm;

[0066] (3) adding ammonia-containing recycled water with an ammonia nitrogen concentration of 45000 ppm to the oil-removed high-purity niobium solution and the oil-removed high-purity tantalum solution respectively, to obtain mother liquor after neutralization precipitation and pressure filtration; and washing the filter residue with ammonia-containing recycled water, and performing pressure filtration again to obtain washing water, and obtaining niobium oxide and tantalum oxide products by drying and calcining the filter residue; the volume ratio of the ammonia-containing recycled water to the oil-removed high-purity niobium solution is 2.2:1, and the volume ratio of the ammonia-containing recycled water to the oil-removed high-purity tantalum solution is 3:1; during the neutralization precipitation, the pH of the solution is 8.5-10.

[0067] (4) sequentially performing step-by-step precipitation and silicon carbide ceramic membrane filtration on the washing water and the mother liquor respectively to obtain filtered washing water and filtered mother liquor; the COD of the filtered washing water is 60 ppm, and the COD of the filtered mother liquor is 260 ppm.

[0068] (5) sequentially concentrating the filtered washing water through ultrafiltration membrane, RO membrane and electrodialysis concentration membrane, and finally concentrating the filtered washing water through reverse osmosis membrane to obtain concentrated ammonia-containing recycled water and low-fluorine pure water;

[0069] (6) The concentration of the concentrated ammonium fluoride water obtained by concentrating the filtrated mother liquor and the filtrated washing water through multi-stage membranes is 5-6wt%, and the concentrated ammonium fluoride water is preheated to 50-55℃, and the concentration of the ammonium fluoride in the concentrated ammonium fluoride water is 8-14wt%. Then, the concentrated ammonium fluoride water is concentrated through low-temperature vacuum evaporation at 63-65℃ and under a pressure of -85 to -90kpa to obtain saturated ammonium fluoride solution and condensed water, and the concentration of ammonia nitrogen in the condensed water is 5000ppm. The stoichiometric amount of chemical pure hydrofluoric acid is added to the condensed water to obtain ammonium fluoride aqueous solution, and the addition of the hydrofluoric acid is stopped when the solution is neutral, and the ammonium fluoride aqueous solution is transferred to the three-stage membrane concentration treatment for the next batch of production to obtain concentrated ammonium fluoride water and low-fluorine pure water; the saturated ammonium fluoride solution is crystallized and centrifuged to obtain ammonium fluoride crystals, and the purity of the ammonium fluoride crystals is 96%. The aqueous solution produced after centrifugation is used as concentrated ammonium fluoride water into the preheater for the next batch of production.

[0070] The above examples only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as the limitation of the patent scope of the present application. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A recycling treatment process for alkaline wastewater from tantalum-niobium hydrometallurgical processes, characterized in that, Includes the following steps: Recycled low-fluoride pure water was added to fluoroniobic acid solution and fluorotantalic acid solution respectively for back-extraction to obtain high-purity niobium solution and high-purity tantalum solution; The high-purity niobium solution and the high-purity tantalum solution are subjected to oil-water separation to remove organic extractant, resulting in oil-free high-purity niobium solution and oil-free high-purity tantalum solution. Ammonia-containing recycled water was added to the degreased high-purity niobium solution and the degreased high-purity tantalum solution, respectively. After neutralization, precipitation, and pressure filtration, mother liquor was obtained. The filter residue was washed with the ammonia-containing recycled water and then filtered again to obtain wash water. The filter residue was dried and calcined to obtain niobium oxide and tantalum oxide products. The wash water and the mother liquor were respectively subjected to step-by-step sedimentation and ceramic membrane filtration to obtain filtered wash water and filtered mother liquor. The filtered wash water is subjected to multi-stage membrane concentration and reverse osmosis membrane concentration to obtain concentrated ammonia-containing recycled water and low-fluoride pure water; The ammonium fluoride concentrate obtained by concentrating the filtrate mother liquor and the filtrate wash water through the multi-stage membrane is preheated and concentrated by low-temperature vacuum evaporation to obtain a saturated ammonium fluoride solution and condensate. Chemically pure hydrofluoric acid is added to the condensate to obtain an aqueous ammonium fluoride solution. The aqueous ammonium fluoride solution is then transferred to the multi-stage membrane concentration treatment to obtain ammonium fluoride concentrate and the low-fluoride pure water. The saturated ammonium fluoride solution is crystallized and centrifuged to obtain ammonium fluoride crystals.

2. The recycling treatment process for alkaline wastewater from tantalum-niobium hydrometallurgical processes as described in claim 1, characterized in that, During the back-extraction process, the volume ratio of the low-fluoride pure water to the fluoroniobic acid solution is 0.3-0.8:1, and the acidity of the back-extraction system is 2.8-3.2 mol / L.

3. The recycling treatment process for alkaline wastewater from tantalum-niobium hydrometallurgical processes as described in claim 1, characterized in that, The oil-water separation process involves removing the upper organic extractant through a multi-stage precipitation method. The COD of the de-oiled high-purity niobium solution is 400-1000 ppm, and the COD of the de-oiled high-purity tantalum solution is 600-1500 ppm.

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

5. The recycling treatment process for alkaline wastewater from tantalum-niobium hydrometallurgical processes as described 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 hydrometallurgical processes as described in claim 1, characterized in that, The multi-stage membrane concentration is a three-stage or four-stage concentration, using ultrafiltration membranes, RO membranes, and electrodialysis concentration membranes.

7. The recycling treatment process for alkaline wastewater from tantalum-niobium hydrometallurgical processes as described in claim 1, characterized in that, The concentration of ammonia nitrogen in the ammonia-containing recycled water is 30,000-60,000 ppm.

8. The recycling treatment process for alkaline wastewater from tantalum-niobium hydrometallurgical processes as described in claim 1, characterized in that, The concentration of ammonia nitrogen in the condensate is 5000-8000 ppm.

9. The recycling treatment process for alkaline wastewater from tantalum-niobium hydrometallurgical processes as described in claim 1, characterized in that, The COD of the filtered wash water is 0-100 ppm, and the COD of the filtered mother liquor is 200-300 ppm.

10. A recycling treatment process for alkaline wastewater from tantalum-niobium hydrometallurgical processes as described in any one of claims 1-9, characterized in that, The low-temperature vacuum evaporation concentration is carried out at a temperature of 55-65 ℃ and a pressure of -90~-80 kPa.

Images