Process for treating tantalum-niobium raw materials

Abstract

The tantalum-niobium raw material processing method provided by the application belongs to the technical field of tantalum-niobium extraction processing, and firstly connects the extraction of the tantalum-niobium raw material with the recovery processing technology of the leaching residue, and constructs a complete closed-circuit system, which not only ensures the extraction of the tantalum-niobium loaded organic phase in the tantalum-niobium raw material, but also ensures that the leaching rates of the tantalum oxide and the niobium oxide in the leaching residue can both reach more than 90%, so that the large amount of accumulated leaching residue rich in tantalum and niobium is changed from waste to treasure. Taking 17 tons of leaching residue (Ta2O5 is 46.75%, Nb2O5 is 5.98%) accumulated by the enterprise as an example, about 7.1 tons of Ta2O5 and 0.9 tons of Nb2O5 can be additionally recovered, and the utilization rate of the tantalum-niobium raw material is improved.

Description

Technical Field

[0001] This invention relates to the field of tantalum and niobium extraction and processing technology, and particularly to a method for processing tantalum and niobium raw materials. Background Technology

[0002] Tantalum (Ta) and niobium (Nb) are essential rare metals. Due to their excellent corrosion resistance, high melting point, unique electrical properties, and good biocompatibility, they are widely used in high-tech fields such as the electronics industry (e.g., tantalum capacitors), aerospace, military equipment, superconducting materials, and medical devices.

[0003] Currently, global tantalum and niobium raw materials mainly come from primary minerals such as tantalum-niobium iron ore and pyrochlore, as well as secondary resources such as tantalum-niobium processing waste, spent catalysts, and electronic waste. Known common metallurgical methods for tantalum and niobium mainly include acid decomposition, alkali decomposition, and chlorination, used to produce high-purity tantalum oxide (Ta₂O₅), niobium oxide (Nb₂O₅), and potassium fluorotantalate (K₂TaF₇). Among these, hydrofluoric acid decomposition has become the mainstream process for industrial processing of tantalum and niobium raw materials due to its high efficiency and selectivity.

[0004] However, the aforementioned traditional methods, especially the mainstream hydrofluoric acid decomposition process, are not suitable for certain tantalum-niobium compounds with dense structures, stable chemical properties, or containing insoluble encapsulated phases (such as certain tungsten-tantalum solid solutions). 14.8 W 1.2 O 40.6 The treatment effect of materials such as tantalum oxide formed by high-temperature processing is limited. Even under optimized strong acid media and temperature conditions, the decomposition efficiency of these materials is still low, resulting in some valuable tantalum and niobium failing to leach out. As a result, they gradually accumulate in the process to form insoluble residues, which are usually called "leaching residue" or "secondary leaching residue".

[0005] These leaching residues still contain a considerable amount of tantalum and niobium. For example, in about 17 tons of such residues accumulated by a smelting company, the Ta2O5 content was as high as 46.75% and the Nb2O5 content was 5.98%, indicating significant recovery value.

[0006] Therefore, developing a new technology that can effectively destroy such difficult-to-decompose phases and efficiently convert tantalum and niobium into easily processed forms is of urgent technical and industrial importance for improving resource utilization, reducing the stockpiling of hazardous solid waste, enhancing corporate economic benefits, and promoting green smelting transformation. Summary of the Invention

[0007] In view of this, it is necessary to provide a method for processing tantalum and niobium raw materials to improve resource utilization, thereby reducing the accumulation of hazardous solid waste and improving the economic benefits of enterprises.

[0008] The technical solution adopted by this invention to solve its technical problem is:

[0009] This invention provides a method for processing tantalum-niobium raw materials, comprising the following steps:

[0010] S1: Hydrofluoric acid is added to tantalum-niobium raw materials to obtain a mixture;

[0011] S2: After adding sulfuric acid to the mixture to carry out a decomposition reaction, the mixture is filtered to obtain tantalum-niobium decomposition solution and leaching residue;

[0012] S3: The tantalum-niobium decomposition solution is extracted with methyl isobutyl ketone to separate the tantalum-niobium supported organic phase. The leaching residue is then ground and mixed with sodium salt to obtain a mixture.

[0013] S4: The mixture is roasted to convert the sparingly soluble tantalum and niobium compounds in the leaching residue into acid-soluble tantalum and niobate salts, thereby obtaining the roasted product;

[0014] S5: The roasted product is subjected to multi-stage leaching treatment to dissolve and remove excess sodium salt and soluble impurities, and tantalum and niobium are dissolved in the solution to obtain acid leaching solution and filter residue.

[0015] S6: Add acid to the acid leaching solution to adjust the pH value, and obtain a standardized solution with an acidity matching that of the tantalum-niobium decomposition solution;

[0016] S7: Return the standardized feed solution to S3 above, so that the standardized feed solution can be combined with the tantalum-niobium decomposition solution or extracted separately, thereby recycling the tantalum-niobium in the leaching residue.

[0017] Preferably, in step S1, the concentration of hydrofluoric acid is 40-60 wt%, and the solid-liquid ratio of the tantalum-niobium raw material to the hydrofluoric acid is 1:(2-5) kg / L; in step S2, the concentration of sulfuric acid is 85-98 wt%, and the solid-liquid ratio of the sulfuric acid to the tantalum-niobium raw material is 1:(1-3) kg / L.

[0018] Preferably, in step S2, the temperature of the decomposition reaction is 70-95°C, and the reaction time is 4-8 hours.

[0019] Preferably, in step S3, the sodium salt is sodium hydroxide or sodium carbonate, and the mass ratio of the sodium salt to the leaching residue is (0.5:1)-(3:1); the grinding and mixing is dry ball milling, and the grinding time is 30-120 minutes.

[0020] Preferably, in step S4, the calcination treatment is carried out at a temperature of 300-700°C for 1-3 hours.

[0021] Preferably, step S5 specifically includes the following steps:

[0022] S51: The roasted product is mixed with deionized water for leaching treatment to dissolve and remove excess sodium salt and soluble impurities, and then solid-liquid separation is performed to obtain water leaching residue.

[0023] S52: The water-leached residue is treated with an acid leaching agent to dissolve tantalum and niobium in the water-leached residue into the solution, and then filtered to obtain acid leaching solution and filter residue.

[0024] Preferably, in step S51, the solid-liquid ratio of the calcined product to deionized water is (10:1)-(3:1) kg / L, and the leaching treatment temperature is 20-80℃ and the time is 1-3 hours.

[0025] Preferably, in step S52, the acidic leaching agent is a hydrofluoric acid solution with a concentration of 4-30 mol / L, or a mixed acid of hydrofluoric acid and sulfuric acid. When the acidic leaching agent is a mixed acid of hydrofluoric acid and sulfuric acid, the concentration of hydrofluoric acid in the mixed acid is 2-10 mol / L and the concentration of sulfuric acid is 1-5 mol / L. The solid-liquid ratio of the water leaching residue to the acidic leaching agent is (10:1)-(3:1) kg / L. The temperature of the acid leaching treatment is 20-80℃ and the time is 1-3 hours.

[0026] Preferably, step S6 specifically involves adding hydrofluoric acid and sulfuric acid to the acid leaching solution to adjust the concentration of hydrofluoric acid in the acid leaching solution to 6-8 mol / L and the concentration of sulfuric acid to 3-4 mol / L, thereby obtaining a standardized solution.

[0027] Preferably, in steps S3 and S7, the volume ratio of methyl isobutyl ketone to the tantalum-niobium-containing aqueous phase is (0.5:1)-(2:1), the number of extraction stages is 18-22, and the extraction method is countercurrent extraction. The tantalum-niobium-containing aqueous phase includes at least one of the standardized feed solution and the tantalum-niobium decomposition solution.

[0028] Compared with existing technologies, the advantages of this invention are as follows: This invention is the first to connect the extraction of tantalum and niobium raw materials with the recycling process of their leaching residue, constructing a complete closed-loop recycling system. This not only ensures the extraction of the tantalum and niobium-loaded organic phase from the tantalum and niobium raw materials, but also guarantees that the leaching rates of tantalum oxide and niobium oxide in the leaching residue can both reach over 90%, turning a large amount of stockpiled tantalum and niobium-rich leaching residue into valuable resources. For example, with a company's stockpiled 17 tons of leaching residue (Ta2O5 46.75%, Nb2O5 5.98%), approximately 7.1 tons of Ta2O5 and 0.9 tons of Nb2O5 can be additionally recovered. Specifically, this invention effectively destroys the stable structure of insoluble compounds in the leaching residue by calcining the mixture formed by the leaching residue and sodium salt, thus reducing the leaching residue... The sparingly soluble tantalum and niobium compounds are converted into acid-soluble tantalum-niobate salts. The calcined products are then subjected to multi-stage leaching to remove excess sodium salts and soluble impurities, reducing subsequent acid consumption and improving leaching selectivity. After efficiently dissolving tantalum and niobium in the water leaching residue, acid leaching solution and filter residue are obtained. Acid is then added to the acid leaching solution to adjust the pH value, making the acid leaching solution compatible with the tantalum-niobium decomposition solution in terms of acidity and composition, resulting in a standardized solution. This standardized solution can be directly combined with the tantalum-niobium decomposition solution or returned separately for extraction treatment, thereby recycling tantalum and niobium in the leaching residue and improving the utilization rate of tantalum and niobium raw materials. Attached Figure Description

[0029] Figure 1 A flowchart of the method for processing tantalum and niobium raw materials provided by the present invention. Detailed Implementation

[0030] To better understand the present invention, the invention will be further described below with reference to embodiments, but the scope of protection of the present invention is not limited to the scope described in the embodiments.

[0031] Please refer to Figure 1 This invention provides a method for processing tantalum-niobium raw materials, comprising the following steps:

[0032] S1: Hydrofluoric acid is added to tantalum-niobium raw materials to obtain a mixture;

[0033] S2: After adding sulfuric acid to the mixture to carry out a decomposition reaction, the mixture is filtered to obtain tantalum-niobium decomposition solution and leaching residue;

[0034] S3: The tantalum-niobium decomposition solution is extracted using methyl isobutyl ketone (MIBK) to separate the tantalum-niobium supported organic phase. The leaching residue is then ground and mixed with sodium salt to obtain a mixture. Specifically, the components (based on oxides) in the leaching residue can be divided into 40%-50% Ta2O5, 5%-10% Nb2O5, and the remainder consists of unreacted impurities, gangue components, and possibly encapsulated insoluble substances.

[0035] S4: The mixture is roasted to convert the sparingly soluble tantalum-niobium compound in the leaching residue into acid-soluble tantalum-niobate, thereby obtaining the roasted product;

[0036] S5: The roasted product is subjected to multi-stage leaching treatment to dissolve and remove excess sodium salt and soluble impurities (such as silicates), enrich tantalum and niobium and reduce subsequent acid consumption, and dissolve tantalum and niobium in the solution to obtain filter residue and acid leaching solution rich in tantalum and niobium.

[0037] S6: Add acid to the acid leaching solution to adjust the pH value, and obtain a standardized solution with an acidity matching that of the tantalum-niobium decomposition solution;

[0038] S7: Return the standardized feed solution to S3 above, so that the standardized feed solution can be combined with the tantalum-niobium decomposition solution or extracted separately, thereby recycling the tantalum-niobium in the leaching residue.

[0039] Compared with existing technologies, the advantages of this invention are as follows: This invention is the first to connect the extraction of tantalum and niobium raw materials with the recycling process of their leaching residue, constructing a complete closed-loop recycling system. This not only ensures the extraction of the tantalum and niobium-loaded organic phase from the tantalum and niobium raw materials, but also guarantees that the leaching rates of tantalum oxide and niobium oxide in the leaching residue can both reach over 90%, turning a large amount of stockpiled tantalum and niobium-rich leaching residue into valuable resources. For example, with a company's stockpiled 17 tons of leaching residue (Ta2O5 46.75%, Nb2O5 5.98%), approximately 7.1 tons of Ta2O5 and 0.9 tons of Nb2O5 can be additionally recovered. Specifically, this invention effectively destroys the stable structure of insoluble compounds in the leaching residue by calcining the mixture formed by the leaching residue and sodium salt, thus reducing the leaching residue... The sparingly soluble tantalum and niobium compounds are converted into acid-soluble tantalum-niobate salts. The calcined products are then subjected to multi-stage leaching to remove excess sodium salts and soluble impurities, reducing subsequent acid consumption and improving leaching selectivity. After efficiently dissolving tantalum and niobium in the water leaching residue, acid leaching solution and filter residue are obtained. Acid is then added to the acid leaching solution to adjust the pH value, making the acid leaching solution compatible with the tantalum-niobium decomposition solution in terms of acidity and composition, resulting in a standardized feed solution. This standardized feed solution can be directly combined with the tantalum-niobium decomposition solution or returned separately for extraction treatment, thereby recycling tantalum and niobium in the leaching residue and improving the utilization rate of tantalum and niobium raw materials.

[0040] Furthermore, in step S1, the concentration of hydrofluoric acid is 40-60 wt%, and the solid-liquid ratio of the tantalum-niobium raw material to the hydrofluoric acid is 1:(2-5) kg / L; in step S2, the concentration of sulfuric acid is 85-98 wt%, and the solid-liquid ratio of the sulfuric acid to the tantalum-niobium raw material is 1:(1-3) kg / L.

[0041] Furthermore, in step S2, the decomposition reaction is carried out at a temperature of 70-95°C for 4-8 hours.

[0042] Furthermore, in step S3, the sodium salt is sodium hydroxide or sodium carbonate. Preferably, the sodium salt is sodium hydroxide, which has higher reactivity, and the mass ratio of the sodium salt to the leaching residue is (0.5:1)-(3:1). The grinding and mixing is done by dry ball milling for 30-120 minutes to ensure that the sodium salt and the residue particles reach close contact at the molecular level, laying the foundation for the subsequent roasting reaction. The ball-to-material ratio of the ball mill should be controlled between (5:1) and (10:1) to ensure good grinding effect.

[0043] Furthermore, in step S4, the calcination treatment temperature is 300-700℃ and the time is 1-3 hours. If the temperature is too low (below 300℃), the reaction between the tantalum-niobium compound and the sodium salt will be insufficient. If the temperature is too high (above 700℃), it will reduce the sintering reactivity of the material and increase energy consumption. Preferably, the calcination treatment temperature range is 500℃-700℃. Within this temperature range, the reaction between the tantalum-niobium compound and the sodium salt can proceed fully, generating stable tantalumates and niobates that are easy to process later. In addition, the heating rate during the calcination treatment is controlled at 5~10℃ / min to avoid sudden temperature rises that could lead to sintering or volatilization losses of the material. The calcination equipment can be a muffle furnace, rotary kiln, or box-type resistance furnace, etc., preferably a muffle furnace with precise temperature control and a uniform furnace atmosphere.

[0044] Furthermore, S5 specifically includes the following steps:

[0045] S51: The roasted product is mixed with deionized water for leaching treatment to dissolve and remove excess sodium salt and soluble impurities, and then solid-liquid separation is performed to obtain water leaching residue.

[0046] S52: The water-leached residue is treated with an acid leaching agent to dissolve tantalum and niobium in the water-leached residue into the solution, and then filtered to obtain acid leaching solution and filter residue.

[0047] Furthermore, in step S51, the solid-liquid ratio of the calcined product to deionized water is (10:1)-(3:1) kg / L. The leaching treatment temperature is 20-80℃, and the time is 1-3 hours. The leaching treatment is carried out under stirring conditions, and the stirring speed should be controlled at 300-600 r / min to maintain sufficient particle suspension and enhance the mass transfer process. Deionized water must be used for the leaching treatment to prevent calcium, magnesium, and other metal ions in the water from reacting with introduced fluoride ions in subsequent processes to form insoluble fluoride precipitates. Such precipitates not only interfere with subsequent processes but may also encapsulate or adsorb tantalum and niobium ions, leading to metal loss. After leaching, solid-liquid separation is performed, which can be achieved using conventional separation methods such as plate and frame filtration, centrifugal filtration, or vacuum filtration. The filter residue obtained after separation needs to be washed to recover the entrained effective components. The washing liquid can be returned to the leaching treatment for recycling, thereby improving the overall recovery rate of tantalum and niobium and reducing the consumption of fresh water.

[0048] Furthermore, in step S52, the acidic leaching agent is a hydrofluoric acid solution with a concentration of 4-30 mol / L, or a mixed acid of hydrofluoric acid and sulfuric acid. Considering both leaching efficiency and economy, the acidic leaching agent is preferably a hydrofluoric acid solution with a concentration of 8 mol / L. When the acidic leaching agent is a mixed acid of hydrofluoric acid and sulfuric acid, the concentration of hydrofluoric acid in the mixed acid is 2-10 mol / L and the concentration of sulfuric acid is 1-5 mol / L. The mixed acid can exert a synergistic effect and improve the leaching effect. For example, the presence of sulfuric acid can inhibit the volatilization of hydrofluoric acid, while increasing the ionic strength of the solution and promoting the dissolution of tantalate niobate. The solid-liquid ratio of the water leaching residue to the acidic leaching agent is (10:1)-(3:1) kg / L, and the acid leaching treatment temperature is 20-80℃ and the time is 1-3 hours.

[0049] In a preferred embodiment, in step S52, the temperature of the acid leaching treatment is controlled by a water bath heating method. Furthermore, the acid leaching treatment is carried out under stirring conditions, with the stirring speed maintained at 300-600 r / min, to ensure uniform heat and mass transfer and to avoid excessive local temperature increases that could lead to excessive volatilization of hydrofluoric acid.

[0050] Furthermore, step S6 specifically involves adding hydrofluoric acid (40% or higher concentration) and sulfuric acid (98%) to the acid leaching solution to adjust the concentration of hydrofluoric acid in the acid leaching solution to 6-8 mol / L and the concentration of sulfuric acid to 3-4 mol / L, thereby obtaining a standardized solution. Specifically, the addition must be carried out by titration to ensure that the final indicators of the standardized solution strictly meet the requirements, making the acid leaching solution compatible with the tantalum-niobium decomposition solution in terms of acidity and composition. The acid solution is added slowly and stirred thoroughly to prevent local overheating and the generation of acid mist.

[0051] Furthermore, in steps S3 and S7, the volume ratio of the methyl isobutyl ketone to the tantalum-niobium-containing aqueous phase is (0.5:1) to (2:1), the number of extraction stages is 18-22, and the extraction method is countercurrent extraction. The tantalum-niobium-containing aqueous phase includes at least one of the standardized feed solution and the tantalum-niobium decomposition solution.

[0052] The following embodiments of the present invention demonstrate the processing method and test results of tantalum-niobium raw materials.

[0053] Example 1:

[0054] S1: Take 50g of tantalum-niobium concentrate (its composition, calculated as oxides, is: Ta2O5 content 49.1%, Nb2O5 content 15.8%), grind it to make the particle size less than 100 mesh, and add 150ml of hydrofluoric acid with a mass fraction of 55% (solid-liquid ratio 1:3) to obtain a mixture.

[0055] S2: Add 75 ml of sulfuric acid (solid-liquid ratio 1:1.5) to the mixture, react at 80°C for 3 hours, filter to obtain tantalum-niobium decomposition solution and leaching residue, and weigh the leaching residue to obtain 20 g.

[0056] S3: Methyl isobutyl ketone is added to the tantalum-niobium decomposition solution for extraction treatment. The volume ratio of methyl isobutyl ketone to the tantalum-niobium decomposition solution is 0.8:1, the number of extraction stages is 22, and the extraction method is countercurrent extraction. The tantalum-niobium supported organic phase is separated. 20g of leaching residue obtained in S2 (its composition, calculated as oxides, is: Ta2O5 content 46.75%, Nb2O5 content 5.98%) and 20g of sodium hydroxide (analytical grade) are placed in a small planetary ball mill, i.e., the mass ratio of sodium salt to residue is 1:1. The mixture is ground at 200 rpm for 30 minutes to obtain a mixture.

[0057] S4: The mixture is placed in an alumina crucible and then placed in a box-type muffle furnace. The temperature is increased to 700°C at a rate of 5°C / min, and then calcined at this temperature for 2 hours. After natural cooling, the calcined product is obtained.

[0058] S51: Transfer the calcined product to a 250ml polypropylene beaker, add deionized water, the solid-liquid ratio of the calcined product to the deionized water is 1:5kg / L, and leach for 1 hour at a mechanical stirring speed of 500r / min under a water bath at 20℃. After the reaction is complete, filter the mixture and wash the filter residue 2-3 times with a small amount of deionized water to obtain the water-leached residue.

[0059] S52: Transfer the water-leached residue to another 250ml polypropylene beaker, add a pre-prepared 8mol / L hydrofluoric acid solution (acid leaching agent), the solid-liquid ratio of the water-leached residue to the hydrofluoric acid solution is 1:5kg / L, and react for 1 hour in a room temperature water bath with stirring at 400r / min. After the reaction is complete, filter while hot to obtain a clear acid leaching solution and filter residue.

[0060] S6: Add hydrofluoric acid and sulfuric acid to the acid leaching solution to adjust the concentration of hydrofluoric acid in the acid leaching solution to 7 mol / L and the concentration of sulfuric acid to 3.5 mol / L, so as to obtain a standardized solution.

[0061] S7: Return the standardized feed solution to S3 above, so that the standardized feed solution is combined with the tantalum and niobium decomposition solution or is extracted separately, thereby recycling the tantalum and niobium in the leaching residue to obtain secondary recovered Ta2O5 and Nb2O5.

[0062] The composition of the filter residue obtained in S52 was determined according to the national standard YS / T358.1-2011 "Chemical Analysis Method for Tantalum and Niobium". The filter residue in this example contained 1.04 g of Ta₂O₅ and 0.102 g of Nb₂O₅. Combined with the total mass of Ta₂O₅ (9.35 g) and Nb₂O₅ (1.196 g) in the leaching residue, the leaching rate of tantalum oxide in the acid leaching solution was calculated to be 88.86%, and the leaching rate of niobium oxide in the acid leaching solution was 91.47%.

[0063] Among them, the tantalum oxide leaching rate in the acid leaching solution = 1 - (mass of Ta2O5 in the filter residue / total mass of Ta2O5 in the leaching residue) × 100%; the niobium oxide leaching rate in the acid leaching solution = 1 - (mass of Nb2O5 in the filter residue / total mass of Nb2O5 in the leaching residue) × 100%.

[0064] The filter residue obtained from S52 was weighed and calculated, and the final mass of the filter residue accounted for 24.4% of the mass of the leaching residue (i.e., the final residue rate was 24.4%).

[0065] Comparative example:

[0066] Compared to Example 1, the difference in this comparative example is that in S52, the acid leaching agent was replaced with a 5 mol / L sulfuric acid solution (100 ml), while other conditions remained the same as in Example 1. After the reaction, the resulting filter residue was measured. Analysis showed that when using a 5 mol / L sulfuric acid solution as the acid leaching agent, the leaching rate of tantalum oxide (Ta2O5) in the acid leaching solution of this comparative example decreased sharply to 1.12%, and the leaching rate of niobium oxide (Nb2O5) in the acid leaching solution was only 2.86%. Meanwhile, the mass of the filter residue accounted for 88% of the original leaching residue mass (i.e., the final residue rate was 88%), which was significantly higher than in Example 1.

[0067] The results of the comparative example contrast sharply with those of Example 1. The experimental data clearly demonstrate that hydrofluoric acid has a much stronger selective dissolution ability for tantalum oxide and niobium oxide than sulfuric acid. Sulfuric acid solution alone is almost ineffective at leaching tantalum oxide and niobium oxide, which confirms the irreplaceable role of hydrofluoric acid in achieving efficient tantalum and niobium recovery and highlights the importance of selecting a suitable acidic leaching agent in the method of this invention.

[0068] Example 2:

[0069] Compared with Example 1, the difference in this example is that in S4, the temperature is programmed to rise to 500°C at a rate of 5°C / min, and then calcined at this temperature for 3 hours. Other conditions are the same as in Example 1. After the reaction is completed, the resulting filter residue is measured and weighed. Analysis shows that the tantalum oxide leaching rate in the acid leaching solution of this example is 87.08%, the niobium oxide leaching rate is 92.56%, and the mass of the filter residue accounts for 19.95% of the leaching residue mass (i.e., the final residue rate is 19.95%).

[0070] Example 3:

[0071] Compared with Example 1, the difference in this example is that in S4, the temperature is programmed to rise to 300°C at a rate of 5°C / min, and then calcined at this temperature for 3 hours. Other conditions are the same as in Example 1. After the reaction is completed, the resulting filter residue is measured and weighed. Analysis shows that the tantalum oxide leaching rate in the acid leaching solution of this example is only 32.57%, the niobium oxide leaching rate is 57.39%, and the mass of the filter residue accounts for 54.65% of the leaching residue mass (i.e., the final residue rate is 54.65%).

[0072] Example 4:

[0073] Compared with Example 2, the difference in this example is that in S3, the amount of sodium hydroxide is reduced to 10g (i.e., the mass ratio of sodium salt to leaching residue is 0.5:1), while other conditions are the same as in Example 2. After the reaction is completed, the resulting filter residue is measured and weighed. Analysis shows that in this example, the leaching rate of tantalum oxide in the acid leaching solution decreases to 54.99%, the leaching rate of niobium oxide in the acid leaching solution decreases to 66.40%, and the mass of the filter residue accounts for 43.17% of the mass of the leaching residue (i.e., the final residue rate is 43.17%).

[0074] Example 5:

[0075] Compared with Example 2, the difference in this example is that in S3, the amount of sodium hydroxide is increased to 30g (i.e., the mass ratio of sodium salt to leaching residue is 1.5:1), while other conditions are the same as in Example 2. After the reaction is completed, the resulting filter residue is measured and weighed. Analysis shows that the leaching rate of tantalum oxide in the acid leaching solution of this example is increased to 93.05%, the leaching rate of niobium oxide in the acid leaching solution is increased to 94.36%, and the mass of the filter residue accounts for 19.15% of the mass of the leaching residue (i.e., the final residue rate is 19.15%).

[0076] A comparison of the results from Examples 4 and 5 with those from Example 2 shows that, at a calcination temperature of 500°C, the amount of sodium salt used is a key factor determining the conversion and leaching efficiency of tantalum oxide and niobium oxide. Insufficient sodium salt (Example 4) leads to incomplete reactions, significantly reducing the leaching rates of both tantalum oxide and niobium oxide; while appropriately increasing the amount of sodium salt (Example 5) helps the reaction proceed more fully, thus achieving the optimal leaching rate. A higher slag rate (e.g., 43.17% in Example 4) is related to unreacted raw materials or intermediate product residues. Although sufficient sodium salt (Example 5) generates more water-soluble sodium salt byproducts, these byproducts are effectively removed during the S51 water leaching process and therefore do not affect the final acid leaching effect and high leaching rate.

[0077] Example 6:

[0078] Compared with Example 2, the difference in this example is that in S52, the concentration of the hydrofluoric acid solution is changed to 4 mol / L, while other conditions are the same as in Example 2. After the reaction is completed, the obtained filter residue is measured and weighed. Analysis shows that the leaching rate of tantalum oxide in the acid leaching solution of this example is 86.46%, the leaching rate of niobium oxide in the acid leaching solution is 88.99%, and the mass of the filter residue accounts for 20.70% of the mass of the leaching residue (i.e., the final residue rate is 20.70%).

[0079] A comparison of the results from Example 6 and Example 2 shows that, in Example 6, reducing the concentration of hydrofluoric acid resulted in a certain degree of decline in the leaching rates of both tantalum oxide and niobium oxide, with the decline in niobium oxide being particularly pronounced. Maintaining an appropriate hydrofluoric acid concentration is crucial for achieving efficient and simultaneous recovery of tantalum oxide and niobium oxide.

[0080] Example 7:

[0081] Compared with Example 2, the difference in this example is that in S52, the concentration of the hydrofluoric acid solution is changed to 30 mol / L, while other conditions are the same as in Example 2. After the reaction is completed, the obtained filter residue is measured and weighed. Analysis shows that the leaching rate of tantalum oxide in the acid leaching solution of this example is 85.78%, the leaching rate of niobium oxide in the acid leaching solution is 92.78%, and the mass of the filter residue accounts for 20.65% of the mass of the leaching residue (i.e., the final residue rate is 20.65%).

[0082] A comparison of the results from Example 7 and Example 2 shows that significantly increasing the concentration of hydrofluoric acid to 30 mol / L only slightly increased the leaching rate of niobium oxide (+0.22 percentage points), while the leaching rate of tantalum oxide decreased slightly. This indicates that excessively high concentrations of hydrofluoric acid did not significantly improve the leaching efficiency of tantalum oxide and niobium oxide. Furthermore, using high concentrations of hydrofluoric acid significantly increases reagent costs and leads to higher operational safety and environmental control requirements due to increased acid mist volatilization and corrosiveness. Therefore, considering the overall balance between technical effectiveness, economy, and operational safety, the concentration of approximately 8 mol / L used in Example 2 is more advantageous for industrial applications.

[0083] Example 8:

[0084] Compared with Example 2, the difference in this example is that in S52, the reaction is carried out in a room temperature water bath with stirring at 400 r / min for 3 hours, while other conditions are the same as in Example 2. After the reaction is completed, the obtained filter residue is weighed and calculated. The mass of the filter residue accounts for 17.05% of the mass of the leaching residue (i.e., the final residue ratio is 17.05%).

[0085] The comparison of the results from Example 8 and Example 2 shows that extending the acid leaching time does not significantly contribute to increasing the leaching rates of tantalum oxide and niobium oxide, indicating that the acid leaching process has basically reached equilibrium within a 1-hour reaction time.

[0086] In summary, the experimental results of Examples 1 to 8 and the comparative examples verify the effectiveness of the tantalum-niobium raw material processing method provided by this invention. This invention creatively integrates the extraction of tantalum-niobium raw materials with the recovery and treatment of its leaching residue. By systematically optimizing the sodium roasting temperature and time, sodium salt dosage, acid leaching agent concentration, and acid leaching time, a complete closed-loop circulation system is constructed. Under the preferred conditions shown in Example 5, the leaching rates of tantalum oxide and niobium oxide in the leaching residue can be stably maintained above 93%, successfully achieving efficient recovery of insoluble tantalum-niobium resources that are difficult to process using traditional methods, and enabling the resource utilization of accumulated tantalum-niobium-rich leaching residue.

[0087] The above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the invention. Those skilled in the art will understand that implementing all or part of the above-described embodiments and making equivalent changes in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A method for processing tantalum-niobium raw materials, characterized in that, Includes the following steps: S1: Hydrofluoric acid is added to tantalum-niobium raw materials to obtain a mixture; S2: After adding sulfuric acid to the mixture to carry out a decomposition reaction, the mixture is filtered to obtain tantalum-niobium decomposition solution and leaching residue; S3: The tantalum-niobium decomposition solution is extracted with methyl isobutyl ketone to separate the tantalum-niobium supported organic phase. The leaching residue is then ground and mixed with sodium salt to obtain a mixture. S4: The mixture is roasted to convert the sparingly soluble tantalum and niobium compounds in the leaching residue into acid-soluble tantalum and niobate salts, thereby obtaining the roasted product; the roasting temperature is 500-700℃ and the time is 1-3 hours. S5: The roasted product is subjected to multi-stage leaching treatment to dissolve and remove excess sodium salt and soluble impurities, and tantalum and niobium are dissolved in the solution to obtain acid leaching solution and filter residue. S5 specifically includes the following steps: S51: The roasted product is mixed with deionized water for leaching treatment to dissolve and remove excess sodium salt and soluble impurities, and then solid-liquid separation is performed to obtain water leaching residue. S52: The water leaching residue is treated with an acid leaching agent to dissolve tantalum and niobium in the water leaching residue into the solution, and then filtered to obtain acid leaching solution and filter residue; The acid leaching agent is a hydrofluoric acid solution with a concentration of 4-30 mol / L, or a mixed acid of hydrofluoric acid and sulfuric acid. When the acid leaching agent is a mixed acid of hydrofluoric acid and sulfuric acid, the concentration of hydrofluoric acid in the mixed acid is 2-10 mol / L and the concentration of sulfuric acid is 1-5 mol / L. S6: Add acid to the acid leaching solution to adjust the pH value, and obtain a standardized solution with an acidity matching that of the tantalum-niobium decomposition solution; S7: The standardized feed solution is returned to S3 above, so that the standardized feed solution is combined with the tantalum and niobium decomposition solution or is extracted separately, thereby recycling the tantalum and niobium in the leaching residue and constructing a complete closed-loop circulation system.

2. The method for processing tantalum-niobium raw materials as described in claim 1, characterized in that, In step S1, the concentration of hydrofluoric acid is 40-60 wt%, and the solid-liquid ratio of the tantalum-niobium raw material to the hydrofluoric acid is 1:(2-5) kg / L; in step S2, the concentration of sulfuric acid is 85-98 wt%, and the solid-liquid ratio of the sulfuric acid to the tantalum-niobium raw material is 1:(1-3) kg / L.

3. The method for processing tantalum-niobium raw materials as described in claim 2, characterized in that, In step S2, the decomposition reaction is carried out at a temperature of 70-95°C for 4-8 hours.

4. The method for processing tantalum-niobium raw materials as described in claim 1, characterized in that, In step S3, the sodium salt is sodium hydroxide or sodium carbonate, and the mass ratio of the sodium salt to the leaching residue is (0.5:1)-(3:1); the grinding and mixing is dry ball milling, and the grinding time is 30-120 minutes.

5. The method for processing tantalum-niobium raw materials as described in claim 1, characterized in that, In step S51, the leaching treatment is carried out at a temperature of 20-80°C for 1-3 hours.

6. The method for processing tantalum-niobium raw materials as described in claim 1, characterized in that, In step S52, the acid leaching treatment is carried out at a temperature of 20-80°C for 1-3 hours.

7. The method for processing tantalum-niobium raw materials as described in claim 1, characterized in that, S6 specifically involves adding hydrofluoric acid and sulfuric acid to the acid leaching solution to adjust the concentration of hydrofluoric acid in the acid leaching solution to 6-8 mol / L and the concentration of sulfuric acid to 3-4 mol / L, thereby obtaining a standardized solution.

8. The method for processing tantalum-niobium raw materials as described in claim 1, characterized in that, In steps S3 and S7, the volume ratio of methyl isobutyl ketone to the tantalum-niobium-containing aqueous phase is (0.5:1)-(2:1), the number of extraction stages is 18-22, and the extraction method is countercurrent extraction. The tantalum-niobium-containing aqueous phase includes at least one of the standardized feed solution and the tantalum-niobium decomposition solution.

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