Method for selectively precipitating, separating and recovering tantalum and niobium

Abstract

The invention relates to the technical field of hydrometallurgy, in particular to a method for recovering tantalum and niobium through selective precipitation separation. The method comprises the following steps: carrying out alkaline roasting on a tantalum-niobium material, and leaching to obtain a leaching solution containing tantalum and niobium; and then adding an organic coordination composite precipitator to realize selective precipitation separation of tantalum and niobium. Then carrying out solid-liquid separation to obtain tantalic acid and a niobium-containing solution; and precipitating the niobium-containing solution to obtain niobic acid, and respectively roasting the tantalic acid and the niobic acid to obtain oxides so as to realize effective recovery of tantalum and niobium elements. According to the method, tantalum and niobium can be separated through one-step fluoride-free precipitation, the separation efficiency is high, the process is simple, operation is convenient, environment friendliness is achieved, and negative effects on the environment can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrometallurgy, and particularly to a method for selectively precipitating, separating and recovering tantalum and niobium. Background Art

[0002] Niobium (Nb) and tantalum (Ta) are two refractory rare metals. Both of them have excellent corrosion resistance, superconductivity, high capacitance and biocompatibility, which make them widely used in microelectronic devices, medical implants and new energy fields. Due to the highly similar physical and chemical properties of tantalum and niobium, they often coexist in the same mineral in nature. However, with the decreasing of tantalum and niobium mineral resources, the recovery of secondary tantalum and niobium resources has attracted more and more attention. Therefore, how to efficiently separate tantalum and niobium has become a key link in the recovery process. At present, tantalum-niobium separation technologies include methods such as organic solvent extraction, ion exchange, and chemical precipitation. The development of these technologies is of great significance for improving the recovery rate of tantalum and niobium resources and the product purity.

[0003] The organic solvent extraction method is widely used in the separation and purification of tantalum and niobium. Its principle is to utilize the difference in the distribution coefficients of these two metal ions between the organic phase and the aqueous phase to achieve separation. Chinese Patent Publication No. CN 112481511 A discloses a method for extracting valuable metals such as tantalum and niobium from low-grade polymetallic pyrometallurgical slag. This method includes steps such as slag crushing, two-stage hydrochloric acid leaching, high-temperature and high-pressure alkali leaching, hydrofluoric acid decomposition, tantalum-niobium extraction and separation, back extraction, hydroxide preparation, washing, drying and roasting, and finally obtains high-purity tantalum and niobium oxides, which can be further processed into metallic tantalum and niobium, while recovering valuable metals such as tungsten and tin. This process improves the product purity and metal recovery rate with a fully wet process, and is suitable for large-scale industrial production. However, its process flow is relatively complex, involving multiple fine operation steps, and uses harmful chemicals such as hydrochloric acid and hydrofluoric acid, which poses certain safety risks and environmental pollution hazards, and requires strict safety protection and environmental protection measures.

[0004] Ion exchange method is a method for separating and purifying metal ions based on the selective adsorption and desorption characteristics of ion exchange resins. As described in Chinese Patent Publication No. CN 119530563 A, a method for extracting and separating tantalum-niobium ore is provided. In this method, the tantalum-niobium ore is added to an ammonium bifluoride solution for heating decomposition, and then the decomposition solution is subjected to gradient elution with ion exchange resin as the stationary phase and hydrochloric acid as the mobile phase to obtain niobium fluoride acid, tantalum fluoride acid and residual liquid respectively, thereby realizing the separation of tantalum and niobium. Although this method improves the separation efficiency and purity to a certain extent, it still fails to achieve one-step separation of tantalum and niobium and cannot completely avoid the use of fluorides. This shows that although the ion exchange method has significant advantages in the separation of metal ions, there are still technical deficiencies.

[0005] The chemical precipitation method is a technique for separating tantalum or niobium from each other by adjusting the pH value of the solution or adding specific reagents to form insoluble precipitates of tantalum or niobium. Chinese Patent Publication No. CN 118479537 A provides an environmentally friendly and safe method for producing tantalum oxide and niobium oxide. In this method, a solution containing niobic acid fluoride and tantalum acid fluoride reacts with a synthetic agent to form sodium niobate and sodium tantalate precipitates. After washing to remove sodium fluoride, hydrolysis agents are used to convert them into niobium hydroxide and tantalum hydroxide. After washing again to remove impurities and then drying and roasting, high-purity oxides are obtained. Similarly, Chinese Patent Publication No. CN 118851261 A introduces an innovative method for precipitating tantalum and niobium solutions and recycling wastewater with added value. By adding an ammonia-free precipitating agent to an acidic tantalum / niobium solution, tantalum / niobium precipitates are promoted to form. Further, after the generated fluoboric acid wastewater is treated by evaporation and crystallization, a fluoboric acid sodium product with economic value and pure water that can be recycled are obtained. Both of these methods avoid the use of ammonia water, achieve the discharge of ammonia-nitrogen-free wastewater, thereby reducing the environmental protection pressure and safety risks. However, at present, these methods are only applicable to separated tantalum solutions or niobium solutions, and there are still certain limitations in the treatment of tantalum-niobium mixed solutions, and the separation of tantalum and niobium cannot be directly achieved. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a method for selectively precipitating, separating, and recovering tantalum and niobium, including: (1) Mixing tantalum-niobium materials with potassium hydroxide and then roasting to obtain soluble tantalum-niobium compounds; (2) Leaching the soluble tantalum-niobium compounds with water to obtain a leaching solution containing tantalum and niobium; (3) Reacting the leaching solution containing tantalum and niobium with an organic acid and a complexing agent, and separating the solid-liquid mixture to obtain tantalum acid precipitates and a niobium-containing solution; (4) Adjusting the pH of the niobium-containing solution and then centrifuging to obtain niobium acid precipitates; (5) Roasting the tantalum acid precipitates and niobium acid precipitates to obtain tantalum pentoxide and niobium pentoxide.

[0007] Preferably, in step (1), the mass ratio of the tantalum-niobium materials to potassium hydroxide is 1:(3 - 5).

[0008] Preferably, in step (1), the roasting temperature is 400°C - 600°C.

[0009] Preferably, in step (2), the leaching temperature is 50°C - 70°C.

[0010] Preferably, in step (2), the mass ratio of the soluble tantalum-niobium compounds to water is 1:(15 - 25).

[0011] Preferably, in step (2), the water is deionized water.

[0012] Preferably, in step (3), the organic acid is formic acid, oxalic acid, malonic acid, tartaric acid or citric acid; the complexing agent is hydroxylamine hydrochloride, ammonium oxalate, sodium chloride, ammonium acetate, ethylenediaminetetraacetic acid or ethylenediamine.

[0013] Preferably, in step (3), the concentration of the organic acid is 0.25 - 0.45 mol / L; the concentration of the complexing agent is 20 - 100 mmol / L.

[0014] Preferably, in step (3), the temperature of the reaction is 30°C - 90°C.

[0015] Preferably, in step (3), the temperature of the reaction is controlled by a water bath.

[0016] Preferably, in step (3), the reaction is carried out under stirring, the stirring speed is 400 - 500 r / min, and the reaction time is 5 - 60 min.

[0017] Preferably, in step (4), the pH is adjusted to 6 - 9.

[0018] Preferably, in step (5), the roasting temperature is 500°C - 1000°C.

[0019] More preferably, the method includes: (1) Mix tantalum-niobium materials with potassium hydroxide at a mass ratio of 1:(3 - 5) and roast at 400°C - 600°C to obtain soluble tantalum-niobium compounds; (2) Leach the soluble tantalum-niobium compounds with water at 50°C - 70°C to obtain a tantalum-niobium-containing leaching solution; (3) Mix the tantalum-niobium-containing leaching solution with oxalic acid and hydroxylamine hydrochloride, and react under stirring at 85°C - 90°C. The concentration of oxalic acid in the mixed solution is 0.35 - 0.45 mol / L, and the concentration of hydroxylamine hydrochloride is 55 - 65 mmol / L; then separate the solid-liquid mixture to obtain tantalum acid precipitate and niobium-containing solution; (4) Adjust the pH of the niobium-containing solution to 7.8 - 8.2 and then centrifuge to obtain niobic acid precipitate; (5) Roast the tantalum acid precipitate and niobic acid precipitate to obtain tantalum pentoxide and niobium pentoxide.

[0020] Preferably, the roasting temperature is 750°C - 850°C.

[0021] Preferably, the roasting time is 2 - 5 h.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a method for selectively precipitating and separating tantalum and niobium. In this method, tantalum and niobium materials are subjected to alkaline roasting, and after leaching, a leaching solution containing tantalum and niobium is obtained. Then, an organic coordination complex precipitant is added to achieve the selective precipitation and separation of tantalum and niobium. Thereafter, solid-liquid separation is carried out to obtain tantalum acid and a niobium-containing solution. The niobium-containing solution is precipitated to obtain niobium acid, and tantalum acid and niobium acid are respectively calcined to obtain oxides, thereby realizing the effective recovery of tantalum and niobium elements. The method of the present invention can precipitate and separate tantalum and niobium without fluorine in one step, with high separation efficiency, simple process, convenient operation, environmental protection and greenness, which is conducive to reducing the negative impact on the environment. Description of the Drawings

[0023] Figure 1 It is the XRD pattern of Ta2O5 obtained after roasting in Example 5.

[0024] Figure 2 It is the XRD pattern of Nb2O5 obtained after roasting in Example 5. Detailed Embodiments

[0025] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. In the embodiments provided in this specification, those not specifying specific techniques or conditions shall follow the techniques or conditions described in the literature in this field or the product specifications. Those reagents or instruments not indicating the manufacturer can be conventional products obtained through regular channels. The tantalum and niobium materials in the following embodiments are tantalum and niobium mixed oxides (the mass ratio of tantalum pentoxide to niobium pentoxide is 1:1).

[0026] Example 1 This example provides a method for selectively precipitating and separating tantalum and niobium, and the steps are as follows: (1) Weigh 1 g of tantalum and niobium mixed oxides and 4 g of potassium hydroxide, and place them together in a crucible. Put the crucible into a muffle furnace, and heat it at a heating rate of 10 °C / min. After heating to 500 °C, roast for 2 h to obtain soluble tantalum and niobium compounds. Subsequently, add 100 mL of deionized water, and leach for 1 h at 60 °C to finally obtain a solution containing tantalum and niobium.

[0027] (2)Measure 20 mL of the tantalum-niobium leaching solution and place it in a water bath environment with a constant temperature of 90 °C. Add solid malonic acid to make its concentration 0.40 mol / L, and solid hydroxylamine hydrochloride to make its concentration 60 mmol / L. Set the stirring speed to 450 r / min and let the solution react continuously for 30 min. After the reaction, perform centrifugation. After detection, the precipitation rate of tantalum at this time is 99.49%, the precipitation rate of niobium is 99.46%, and the separation coefficient of the two is 1.07.

[0028] (3)Carefully wash the obtained tantalum precipitate and niobium precipitate three times with 0.01 mol / L malonic acid solution to ensure that the impurities on the surface of the precipitate are fully removed. After washing, dry the precipitate. The dried precipitate is transferred to a muffle furnace and calcined at a high temperature of 900 °C for 2 h to finally successfully obtain Ta2O5 and Nb2O5.

[0029] Example 2 This example provides a method for selectively precipitating and separating and recovering tantalum and niobium, and the steps are as follows: (1)Weigh 1 g of tantalum-niobium mixed oxide and 4 g of potassium hydroxide and place them together in a crucible. Put the crucible into a muffle furnace and heat it up at a heating rate of 10 °C / min. After heating to 500 °C, calcine for 2 h to obtain a soluble tantalum-niobium compound. Subsequently, add 100 mL of deionized water and leach for 1 h at 60 °C to finally obtain a solution containing tantalum and niobium.

[0030] (2)Measure 20 mL of the tantalum-niobium leaching solution and place it in a water bath environment with a constant temperature of 60 °C. Add solid oxalic acid to make its concentration 0.40 mol / L, and solid ethylenediaminetetraacetic acid to make its concentration 45 mmol / L. Set the stirring speed to 450 r / min and let the solution react continuously for 60 min. After the reaction, perform centrifugation. After detection, the precipitation rate of tantalum at this time is 81.95%, while the precipitation rate of niobium is 7.73%, and the separation coefficient of the two is 54.21.

[0031] (3)For the solution rich in niobium after separation, slowly add KOH to adjust the pH value. Stop adding when the pH value reaches 8. Under this condition, the precipitation rate of niobium can reach 99.99%, but almost all the tantalum in the solution also precipitates at this time.

[0032] (4) The obtained tantalum precipitate and niobium precipitate were carefully washed three times with 0.01 mol / L malonic acid solution to ensure that the impurities on the surface of the precipitate were fully removed. After washing, the precipitate was dried. The dried precipitate was transferred to a muffle furnace and calcined at a high temperature of 800 °C for 2 h, and finally Ta2O5 and Nb2O5 were successfully obtained.

[0033] Example 3 This example provides a method for selectively precipitating and separating and recovering tantalum and niobium, and the steps are as follows: (1) Weigh 1 g of tantalum-niobium mixed oxide and 4 g of potassium hydroxide and place them in a crucible together. The crucible was placed in a muffle furnace and heated to 500 °C at a heating rate of 10 °C / min and calcined for 2 h to obtain a soluble tantalum-niobium compound. Subsequently, 100 mL of deionized water was added and leached for 1 h at 60 °C to finally obtain a solution containing tantalum and niobium.

[0034] (2) Measure 20 mL of the tantalum-niobium leaching solution and place it in a water bath environment with a constant temperature of 60 °C. Add solid oxalic acid to make its concentration 0.38 mol / L, and solid hydroxylamine hydrochloride to make its concentration 45 mmol / L. Set the stirring speed to 450 r / min and let the solution react for 60 min; after the reaction, perform centrifugation. After detection, the precipitation rate of tantalum was as high as 99.45% at this time, while the precipitation rate of niobium was 30.84%, and the separation coefficient of the two reached 383.02.

[0035] (3) For the solution rich in niobium after separation, slowly add KOH to adjust the pH value. Stop adding when the pH value reaches 9. Under this condition, the precipitation rate of niobium can reach 89.40%.

[0036] (4) The obtained tantalum precipitate and niobium precipitate were carefully washed three times with 0.01 mol / L malonic acid solution to ensure that the impurities on the surface of the precipitate were fully removed. After washing, the precipitate was dried. The dried precipitate was transferred to a muffle furnace and calcined at a high temperature of 800 °C for 2 h, and finally Ta2O5 and Nb2O5 were successfully obtained.

[0037] Example 4 This example provides a method for selectively precipitating and separating and recovering tantalum and niobium, and the steps are as follows: (1) Weigh 1 g of tantalum-niobium mixed oxide and 4 g of potassium hydroxide, and place them together in a crucible. Put the crucible into a muffle furnace, and heat it up to 500 °C at a heating rate of 10 °C / min, then calcine for 2 h to obtain soluble tantalum-niobium compounds. Subsequently, add 100 mL of deionized water, and leach for 1 h at 60 °C to finally obtain a solution containing tantalum and niobium.

[0038] (2) Measure 20 mL of the tantalum-niobium leaching solution, place it in a water bath environment with a constant temperature of 60 °C, add solid oxalic acid to make its concentration 0.42 mol / L, and solid hydroxylamine hydrochloride to make its concentration 60 mmol / L. Set the stirring speed to 450 r / min, and let the solution react continuously for 30 min; after the reaction is completed, perform centrifugation. After detection, the precipitation rate of tantalum at this time is as high as 91.43%, while the precipitation rate of niobium is 4.24%, and the separation coefficient of the two reaches 251.63.

[0039] (3) Slowly add KOH to adjust the pH value of the solution rich in niobium after separation, and stop adding when the pH value reaches 7. Under this condition, the precipitation rate of niobium only reaches 53.12%.

[0040] (4) Carefully wash the obtained tantalum precipitate and niobium precipitate three times with 0.01 mol / L malonic acid solution to ensure that the impurities on the surface of the precipitate are fully removed. After washing, dry the precipitate. The dried precipitate is transferred into a muffle furnace and calcined at 700 °C for 2 h to finally successfully obtain Ta2O5 and Nb2O5.

[0041] Example 5 This example provides a method for selectively precipitating and separating and recovering tantalum and niobium, and the steps are as follows: (1) Weigh 1 g of tantalum-niobium material and 4 g of potassium hydroxide, and place them together in a crucible. Put the crucible into a muffle furnace, and heat it up to 500 °C at a heating rate of 10 °C / min, then calcine for 2 h to obtain soluble tantalum-niobium compounds. Subsequently, add 100 mL of deionized water, and leach for 1 h at 60 °C to finally obtain a solution containing tantalum and niobium.

[0042] (2) Measure 20 mL of the tantalum-niobium leaching solution and place it in a water bath environment with a constant temperature of 90 °C. Add solid oxalic acid to make its concentration 0.40 mol / L, and solid hydroxylamine hydrochloride to make its concentration 60 mmol / L. Set the stirring speed to 450 r / min and let the solution react continuously for 30 min. After the reaction, perform centrifugation. After detection, the precipitation rate of tantalum is as high as 99.32% at this time, while the precipitation rate of niobium is 8.43%, and the separation coefficient of the two reaches 1588.57.

[0043] (3) For the niobium-rich solution after separation, slowly add KOH to adjust the pH value. Stop adding when the pH value reaches 8. Under this condition, the precipitation rate of niobium can reach 99.99%.

[0044] (4) Wash the obtained tantalum precipitate and niobium precipitate carefully three times with 0.01 mol / L malonic acid solution to ensure that the impurities on the surface of the precipitate are fully removed. After washing, dry the precipitate. The dried precipitate is transferred to a muffle furnace and calcined at a high temperature of 800 °C for 2 h, and finally Ta2O5 and Nb2O5 are successfully obtained.

[0045] The XRD patterns of Ta2O5 and Nb2O5 obtained in this example are respectively as Figure 1 and Figure 2 shown.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for selectively precipitating and separating tantalum and niobium for recovery, characterized in that, Including: (1) Mix tantalum-niobium materials with potassium hydroxide and then roast to obtain soluble tantalum-niobium compounds; (2) Leach the soluble tantalum-niobium compounds with water to obtain a leaching solution containing tantalum and niobium; (3) Mix the leaching solution containing tantalum and niobium with an organic acid and a complexing agent and then react, separate the solid-liquid mixture to obtain tantalum acid precipitate and a niobium-containing solution; (4) Adjust the pH of the niobium-containing solution and then centrifuge to obtain niobic acid precipitate; (5) Roast the tantalum acid precipitate and the niobic acid precipitate to obtain tantalum pentoxide and niobium pentoxide.

2. The method according to claim 1, wherein In step (1), the mass ratio of the tantalum-niobium materials to potassium hydroxide is 1:(3 - 5).

3. The method according to claim 1, characterized in that In step (1), the roasting temperature is 400°C - 600°C.

4. The method according to claim 1, wherein In step (2), the leaching temperature is 50°C - 70°C.

5. The method according to claim 1, characterized in that In step (3), the organic acid is formic acid, oxalic acid, malonic acid, tartaric acid or citric acid; the complexing agent is hydroxylamine hydrochloride, ammonium oxalate, sodium chloride, ammonium acetate, ethylenediaminetetraacetic acid or ethylenediamine.

6. The method according to claim 1, characterized in that In step (3), the concentration of the organic acid is 0.25 - 0.45 mol / L; the concentration of the complexing agent is 20 - 100 mmol / L.

7. The method according to claim 1, wherein In step (3), the reaction temperature is 30°C - 90°C.

8. The method according to claim 1, wherein In step (3), the reaction is carried out under stirring, the stirring speed is 400 - 500 r / min, and the reaction time is 5 - 60 min.

9. The method according to claim 1, characterized in that, In step (4), adjust the pH to 6 - 9.

10. The method according to claim 1, wherein In step (5), the roasting temperature is 500°C - 1000°C.

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