Chlor-alkali coupled niobium-tantalum chlorination rectification separation and purification method

Abstract

The invention relates to a chlor-alkali coupled niobium-tantalum chlorination rectification separation and purification method. Mixing and grinding sodium hydroxide and niobium-tantalum concentrate to obtain a compound; putting the mixture into a high-temperature calcining furnace for high-temperature reaction, dissolving a product into water after full reaction, washing to be neutral, and filtering to obtain a filter cake; the filter cake is subjected to acid pickling and filtering, and niobium-tantalum mixed oxide sediment is obtained; respectively grinding and crushing the oxide precipitate and coke, mixing, adding into a circulating fluidized bed chlorination furnace, and fully reacting with chlorine to obtain gaseous chloride; carrying out cascade condensation on the gaseous chloride to obtain a niobium chloride and tantalum chloride mixture; introducing the mixture into a rectifying tower for high-temperature rectification, and deeply separating and purifying to obtain pure niobium chloride and pure tantalum chloride; niobium chloride and tantalum chloride obtained through rectification are further subjected to hydrogen reduction to obtain niobium and tantalum metal, and the purity is 99.99%-99.9999%.

Description

Technical Field

[0001] The invention belongs to the field of metallurgy and relates to alkali melting, chlorination, distillation separation and refining of niobium-tantalum concentrate; in particular, it relates to a chlorine-alkali coupling chlorination distillation separation and purification method of niobium-tantalum. Background Art

[0002] Niobium and tantalum are rare metals with great use value. They have good electrical and thermal conductivity and are widely used in aerospace, electronics, energy, chemical and other fields. Among them, niobium is widely used in superconductivity, alloys, medical treatment and other fields, while tantalum is widely used in chemical, electronic, electrical and other industries. Both are very important strategic resources.

[0003] Niobium and tantalum often exist in the form of associated minerals in the earth's crust, but the physical and chemical properties of niobium, tantalum metals and their oxides are very similar, and it is very difficult to separate them by conventional metallurgical methods. At present, the common niobium and tantalum separation methods mainly include hydrofluoric acid leaching-organic solvent extraction. However, this production method not only has low extraction efficiency, but also produces a large amount of fluorine-containing and organic waste during the production process. The use of hydrofluoric acid also has safety hazards, and strict safety measures need to be taken. In addition, the grade of niobium and tantalum ores in my country is low, and the content of niobium and tantalum is very low. Common ores often contain elements such as iron, titanium, manganese, and silicon. If they are not separated and recycled, it is a great waste. Therefore, there is an urgent need for a method to efficiently separate and recycle niobium and tantalum from elements such as iron, titanium, manganese, and silicon, while separating the two elements of niobium and tantalum.

[0004] The application number is CN201811121191.1, and the patent name is "A boiling chlorination extraction method for niobium-tantalum concentrate". A method for extracting niobium and tantalum chloride by boiling chlorination is disclosed, which includes the following steps: mixing the niobium-tantalum concentrate with a reducing agent and a stabilizer, adding them into a boiling chlorination furnace, introducing chlorine gas for reaction, and the reaction generates an overflow overflowing from the boiling chlorination furnace, and the overflow is subjected to five consecutive cooling and separation stages; in the five consecutive cooling and separation stages, the temperature of the first cooling and separation stage is 500-700°C, the temperature of the second cooling and separation stage is 250-500°C, the temperature of the third cooling and separation stage is 130-240°C, the temperature of the fourth cooling and separation stage is 70-120°C, and the temperature of the fifth cooling and separation stage is -20-50°C; wherein, the third cooling and separation stage obtains solid niobium tantalum chloride and gaseous chloride. However, this method only realizes the extraction of niobium and tantalum from the concentrate, and the obtained product is only a mixture of niobium and tantalum chlorides, and no high-purity niobium chloride and tantalum chloride, or high-purity niobium and tantalum metals are obtained. Summary of the invention

[0005] The present invention is mainly to solve the technical problems existing in the prior art. The present invention provides a new green niobium and tantalum separation and purification process. The method has less pollution of three wastes and directly produces high-purity niobium chloride, tantalum chloride and high-purity niobium and tantalum. At the same time, it can achieve atomic economy and realize the coupling of chlor-alkali and niobium and tantalum separation and purification.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A chlorine-alkali coupled niobium-tantalum chlorination distillation separation and purification method comprises the following steps:

[0008] (1) mixing sodium hydroxide and niobium-tantalum concentrate and grinding them to obtain a mixture;

[0009] (2) putting the mixture into a high-temperature calcining furnace for high-temperature reaction, dissolving the product in water after sufficient reaction, washing with water until neutral, and filtering to obtain a filter cake;

[0010] (3) acid-washing and filtering the filter cake in step (2) to obtain a niobium-tantalum mixed oxide precipitate;

[0011] (4) grinding and crushing the niobium-tantalum mixed oxide precipitate and the coke respectively, mixing them, adding them to a circulating fluidized bed chlorination furnace to fully react with chlorine gas to obtain gaseous chloride;

[0012] (5) Gaseous chlorides are condensed in stages to obtain a mixture of niobium chloride and tantalum chloride;

[0013] (6) passing the mixture of niobium chloride and tantalum chloride into a distillation tower for high-temperature distillation, deep separation and purification, to obtain pure niobium chloride and pure tantalum chloride;

[0014] (7) The niobium chloride and tantalum chloride obtained by distillation are further reduced by hydrogen to obtain niobium and tantalum metals with a purity of 99.99% to 99.9999%.

[0015] The concentrate in step (1) contains one or both of niobium and tantalum elements, and the mass ratio of the concentrate to sodium hydroxide is 1:0.5 to 1:5.

[0016] In the step (2), a calcining furnace with stirring function, alkali corrosion resistance and high temperature resistance is used, and the temperature of the high temperature calcining furnace is maintained at 500°C to 800°C.

[0017] In the step (3) of pickling, the mass ratio of hydrochloric acid to filter cake is 1:1 to 10.

[0018] In the step (4), the particle size after grinding is controlled at 100-300 meshes, the mass ratio of niobium tantalum oxide to coke is 1:1-3, the chlorination reaction temperature is 700-1500°C, the chlorine gas flow rate is 0.1-0.2 m / s, and the reaction time is 1-2 h.

[0019] In the step (4), the circulating fluidized bed chlorination furnace comprises a cyclone separation device, a circulation device and a reaction device.

[0020] In the step (5), the step condensation temperature is set as follows: 450-600°C in the first section; 255-306°C in the second section; 225-249°C in the third section; 136-220°C in the fourth section; -25-130°C in the fifth section; and -50--35°C in the sixth section.

[0021] In the step (6), the bottom temperature is 254-280°C, the top temperature is 243-253°C, the reflux ratio is 1-4, and the number of theoretical plates is 100-150.

[0022] In the step (7), hydrogen is used for reduction at a reduction temperature of 1000-1500°C.

[0023] The hydrogen and hydrogen chloride mixed gas obtained after reduction in step (7) is absorbed by water, the hydrochloric acid obtained by the reaction of hydrogen chloride and water is used in step (3), and the hydrogen is used in step (7) after dehydration.

[0024] The detailed description is as follows:

[0025] (1) Mixed grinding of alkali and niobium-tantalum concentrate

[0026] The sodium hydroxide and the concentrate are ground and fully mixed in a dry atmosphere at a mass ratio of 1:0.5 to 1:5 to obtain a concentrate mixture.

[0027] (2) Alkali Fusion Reaction

[0028] The concentrate mixture is put into a calcining furnace with stirring function, alkali corrosion resistance and high temperature resistance to react at a high temperature of 500-800°C for 3-8 hours. The reaction product is washed with water until it is neutral and filtered to obtain a filter cake.

[0029] The main reaction equation is: NbO x +NaOH=Na3NbO4+H2O;TaO x +NaOH=Na3TaO4+H2O;

[0030] At this time, silicon and aluminum are removed, and the added sodium hydroxide is removed. The removed silicon and aluminum can be recycled after precipitation, and the sodium hydroxide can be reused in alkali fusion reaction or used to treat the filtrate after pickling after purification.

[0031] (3) Pickling

[0032] Add 0.5-2 mol / L hydrochloric acid to the filter cake in (2) for full reaction, the mass ratio of HCl in the hydrochloric acid to the filter cake is 1:1-5, and the reaction time is 6-12 hours. After the reaction is completed, the solution is allowed to settle, the supernatant is removed, the bottom precipitate is filtered and washed with water until the washing liquid is neutral, and a niobium tantalum mixed oxide precipitate is obtained. The main components of the filtrate are iron, manganese, and unreacted acid, which can be neutralized with the sodium hydroxide solution produced in (2) and recycled.

[0033] (4) Chlorination

[0034] The niobium-tantalum mixed oxide precipitate obtained in (3) is fully dried and then ground and pulverized, and the coke is also ground and pulverized. The particle size of the ground niobium-tantalum mixed oxide and coke is controlled to be 100-300 mesh. The ground niobium-tantalum mixed oxide is mixed with carbon in a mass ratio of 1:1-3, and then added to a circulating fluidized bed chlorination furnace. The chlorination furnace is evacuated and replaced with argon gas. Finally, the furnace temperature is raised to above 700°C and high-purity dry chlorine is introduced to fully react at a high temperature of 700-1200°C. The post-reaction gas is separated by cyclone and then enters the subsequent process. The circulating fluidized bed chlorination furnace should include a cyclone separation device, a circulation device and a reaction device.

[0035] The reaction equations are: Nb2O5+5Cl2+2.5C=2NbCl5+2.5CO2; Ta2O5+5Cl2+2.5C=2TaCl5+2.5CO2

[0036] (5) Purification of niobium and tantalum

[0037] The gas obtained in step (4) is condensed in stages, and the temperature gradient is divided into the following six stages:

[0038] The first stage is 450-600°C to obtain high melting point dust and gaseous chloride. The high melting point dust is captured by bag dust removal, and after water washing, the unreacted niobium, tantalum oxides and carbon powder are returned to (4) for re-granulation and reaction;

[0039] The second stage: 255-306°C, separation to obtain liquid or solid chlorides and gaseous chlorides;

[0040] The third stage: 225-249°C, a mixture of liquid niobium chloride and tantalum chloride, as well as other gaseous chlorides are obtained;

[0041] The fourth stage: 136-220°C, to obtain a partially solid mixture of niobium chloride and tantalum, as well as gaseous chloride;

[0042] The fifth stage: -25~130℃, obtaining liquid titanium tetrachloride, and a mixture of carbon dioxide and chlorine;

[0043] The sixth stage: -50 to -35°C, liquid chlorine and carbon dioxide gas are obtained. The liquid chlorine is purified and returned to step (4) for re-chlorination.

[0044] (6) Separation of niobium and tantalum

[0045] The mixture of niobium chloride and tantalum chloride is separated by distillation. The temperature of the distillation tower is 254-280℃, the temperature of the tower top is 243-253℃, the reflux ratio is 1-4, and the number of theoretical plates is 100-150. At the same time, the intelligent heating system is used in the distillation tower to accurately control the tower temperature to ensure the separation effect of each theoretical plate. After distillation, niobium chloride with a purity of more than 99.99% and tantalum chloride with a purity of 99.99% are obtained.

[0046] (7) Reduction of niobium chloride and tantalum chloride

[0047] The high purity niobium and tantalum chlorides produced in (6) are reduced in a high temperature reduction furnace using hydrogen, wherein the volume ratio of chloride to hydrogen is 1:1.5-4, the reduction temperature is 1000-1500°C, and niobium and tantalum metals with a purity of more than 99.99% are produced.

[0048] The tail gas of the reaction is mainly hydrogen chloride and unreacted hydrogen. After the tail gas is absorbed by water, hydrochloric acid is used for pickling in (3), and the unreacted hydrogen is used for the reduction of niobium and tantalum chlorides after drying.

[0049] According to a chlor-alkali coupled niobium-tantalum chlorination distillation separation and purification process according to a specific embodiment of the present invention, preferably, the sodium hydroxide used in step (1), the hydrochloric acid used in step (3), the chlorine used in step (4), and the hydrogen used in step (7) can be obtained by electrolyzing a sodium chloride solution. By combining the chlor-alkali industry with the present invention, atomic economy can be achieved while avoiding the transportation of hazardous chemicals, thereby improving the economy of the process.

[0050] According to a chlorine-alkali coupled niobium-tantalum chlorination distillation separation and purification process of a specific embodiment of the present invention, preferably, in the concentrate in step (1), the niobium-tantalum concentrate is a niobium-tantalum concentrate with a total mass fraction of Nb2O5 and Ta2O5 of ≥10%. The present invention can also be used for niobium concentrate with a mass fraction of Nb2O5 ≥10% or tantalum concentrate with a mass fraction of Ta2O5 ≥10%.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] (1) While purifying niobium and tantalum metals, the present invention couples the production of chlorine and alkali, recycles the reaction products, and consumes only sodium chloride, niobium-tantalum concentrate and coke as solid materials. High-purity niobium and tantalum are obtained, and many other metals with higher purity are separated. The production is in line with atomic economy, effectively realizing the recycling of resources and high value-added recovery of resources. At the same time, it effectively solves the problem of high pollution from niobium and tantalum refining emissions.

[0053] (2) The present invention can separate and purify niobium and tantalum in concentrates. Through special circulating fluidized bed chlorination technology and high-temperature distillation technology, high-purity niobium chloride and tantalum chloride with a purity of more than 99.99% can be obtained.

[0054] The present invention provides a chlorine-alkali coupled niobium-tantalum chlorination distillation separation and purification process. Various raw materials used in the process for treating concentrates are provided by the chlorine-alkali industry, which conforms to atomic economy. At the same time, water pollution caused by hydrometallurgy is avoided, and pure niobium-tantalum chloride and pure metal are obtained at the same time, which has significant economic and environmental benefits. DETAILED DESCRIPTION

[0055] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0056] Example 1

[0057] (1) grinding niobium-tantalum concentrate and sodium hydroxide in a mass ratio of 1:0.5 to 200 meshes under dry conditions and then mixing them uniformly to obtain a mixture;

[0058] (2) The mixture is placed in a high-temperature calcining furnace and reacted at 500° C. for 8 h. The reaction product is dissolved in water and washed to neutrality, and filtered to obtain a filter cake.

[0059] (3) The filter cake in step (2) is added to 0.5 mol / L hydrochloric acid containing an equal mass of HCl, reacted for 12 h, acid washed, and filtered to obtain a mixed oxide precipitate containing 50% by mass of niobium oxide and tantalum.

[0060] (4) Grinding the niobium tantalum mixed oxide precipitate and coke to 100 mesh, mixing them in a mass ratio of 1:1 and fully drying them, and reacting them with chlorine gas at a flow rate of 0.1 m / s for 1 hour in a circulating fluidized bed chlorination furnace at a reaction temperature of 700° C.; the circulating fluidized bed chlorination furnace comprises a cyclone separation device, a circulation device and a reaction device.

[0061] (5) The gas generated by the reaction is separated into a solid phase by a cyclone separator and then subjected to step condensation; wherein:

[0062] The temperature of the first condenser is 450℃, and high melting point dust and gaseous chloride are obtained. The high melting point dust is captured by bag dust removal, and after water washing, the unreacted niobium, tantalum oxides and coke are returned to the chlorination process for re-granulation and reaction;

[0063] The temperature of the second condenser is 255°C, and a small amount of solid ferric chloride and gaseous chloride are separated;

[0064] The temperature of the third condenser is 225°C, and a liquid niobium-tantalum chloride mixture and other gaseous chlorides are obtained;

[0065] The temperature of the fourth condenser is 136°C, and a small amount of solid niobium chloride, tantalum mixture, and gaseous chloride are obtained;

[0066] The temperature of the fifth condenser is -25°C, and liquid titanium tetrachloride, as well as a mixture of carbon dioxide and chlorine are obtained;

[0067] The temperature of the sixth condenser is -50°C, and liquid chlorine and carbon dioxide gas are obtained, and the liquid chlorine is recycled.

[0068] (6) The liquid niobium chloride and tantalum chloride mixture is introduced into a special distillation tower with a top temperature of 243° C., a bottom temperature of 254° C., a reflux ratio of 3, and a theoretical plate number of 100; the top produced liquid is 99.99% tantalum chloride, and the bottom produced liquid is 99.99% niobium chloride.

[0069] (7) High-temperature reduction of niobium chloride and tantalum chloride to obtain metallic niobium and metallic tantalum; wherein the volume ratio of niobium chloride to hydrogen is 1:4, and the reduction temperature is 1000°C; the volume ratio of tantalum chloride to hydrogen is 1:4, and the reduction temperature is 1000°C, to obtain pure metals of niobium and tantalum with a purity of 99.99% to 99.9999%; the mixed gas after the reaction is absorbed by water, and the volume ratio of gas to water is 1:10; the absorbed aqueous solution is hydrochloric acid, which can be used for recycling, and the hydrogen is used in step (7) after dehydration.

[0070] Example 2

[0071] The method for separating and extracting niobium-tantalum concentrate in this embodiment comprises the following steps:

[0072] (1) grinding niobium-tantalum concentrate and sodium hydroxide in a mass ratio of 1:5 to 200 meshes under dry conditions and then mixing them uniformly to obtain a mixture;

[0073] (2) putting the mixture into a high-temperature calcining furnace and reacting it at 800° C. for 3 hours; dissolving the reaction product in water and washing it to neutrality, and filtering it to obtain a filter cake.

[0074] (3) The filter cake in step (2) was added with 5 times the mass of HCl, 0.5 mol / L hydrochloric acid, reacted for 6 hours for acid washing, and filtered to obtain a mixed oxide precipitate containing 50% by mass of niobium oxide and tantalum.

[0075] (4) Grinding the niobium tantalum mixed oxide precipitate and coke to 200 mesh, mixing them in a mass ratio of 1:5 and fully drying them, reacting them with chlorine gas at a flow rate of 0.2 m / s for 1 hour in a circulating fluidized bed chlorination furnace at a reaction temperature of 1200° C. The circulating fluidized bed chlorination furnace comprises a cyclone separation device, a circulation device and a reaction device.

[0076] (5) The gas generated by the reaction is separated from the solid phase by a cyclone separator and then subjected to step condensation; wherein:

[0077] The temperature of the first condenser is 600℃, and high melting point dust and gaseous chloride are obtained. The high melting point dust is captured by bag dust removal, and after water washing, the unreacted niobium, tantalum oxides and coke are returned to the chlorination process for re-granulation and reaction;

[0078] The temperature of the second condenser is 306°C, and a small amount of solid ferric chloride and gaseous chloride are separated;

[0079] The temperature of the third condenser is 249°C, and a liquid niobium-tantalum chloride mixture and other gaseous chlorides are obtained;

[0080] The temperature of the fourth condenser is 220°C, and a small amount of solid niobium chloride, tantalum mixture, and gaseous chloride are obtained;

[0081] The temperature of the fifth condenser is 130°C, and liquid titanium tetrachloride, as well as a mixture of carbon dioxide and chlorine are obtained;

[0082] The temperature of the sixth condenser is -35°C, and liquid chlorine and carbon dioxide gas are obtained, and the liquid chlorine is recycled.

[0083] (6) The liquid niobium chloride and tantalum chloride mixture is introduced into a special distillation tower with a top temperature of 243° C., a bottom temperature of 280° C., a reflux ratio of 2.5, and a theoretical plate number of 100; the top produced liquid is 99.99% tantalum chloride, and the bottom produced liquid is 99.99% niobium chloride.

[0084] (7) High-temperature reduction of niobium chloride and tantalum chloride to obtain metallic niobium and metallic tantalum; wherein the volume ratio of niobium chloride to hydrogen is 1:1.5, and the reduction temperature is 1500°C; the volume ratio of tantalum chloride to hydrogen is 1:1.5, and the reduction temperature is 1500°C, to obtain pure metals of niobium and tantalum with a purity of 99.99%; the mixed gas after the reaction is absorbed by water, and the volume ratio of gas to water is 1:10; the absorbed aqueous solution is hydrochloric acid, which can be used for recycling, and the hydrogen is used in step (7) after dehydration.

[0085] Example 3

[0086] The method for separating and extracting niobium-tantalum concentrate in this embodiment comprises the following steps:

[0087] (1) grinding niobium-tantalum concentrate and sodium hydroxide in a mass ratio of 1:2 under dry conditions to 200 meshes and then mixing them uniformly to obtain a mixture;

[0088] (2) The mixture is placed in a high-temperature calcining furnace and reacted at 650° C. for 3 hours; the reaction product is dissolved in water and washed until neutral, and filtered to obtain a filter cake.

[0089] (3) The filter cake in step (2) is added to 1 mol / L hydrochloric acid containing 2 times the mass of HCl, reacted for 10 hours for acid washing, and filtered to obtain a mixed oxide precipitate containing 50% by mass of niobium oxide and tantalum.

[0090] (4) Grinding the niobium tantalum mixed oxide precipitate and coke to 100 mesh, mixing them in a mass ratio of 1:3 and fully drying them, reacting them with chlorine gas at a flow rate of 0.1 m / s for 2 hours in a circulating fluidized bed chlorination furnace at a reaction temperature of 1000° C.; the circulating fluidized bed chlorination furnace comprises a cyclone separation device, a circulation device and a reaction device.

[0091] (5) The gas generated by the reaction is separated from the solid phase by a cyclone separator and then subjected to step condensation; wherein:

[0092] The temperature of the first condenser is 500℃, and high melting point dust and gaseous chloride are obtained. The high melting point dust is captured by bag dust removal, and after water washing, the unreacted niobium, tantalum oxides and coke are returned to the chlorination process for re-granulation and reaction;

[0093] The temperature of the second condenser is 270°C, and a small amount of solid ferric chloride and gaseous chloride are separated;

[0094] The temperature of the third condenser is 235°C, and a liquid niobium-tantalum chloride mixture and other gaseous chlorides are obtained;

[0095] The temperature of the fourth condenser is 154°C, and a small amount of solid niobium chloride, tantalum mixture, and gaseous chloride are obtained;

[0096] The temperature of the fifth condenser is 50°C, and liquid titanium tetrachloride and a mixture of carbon dioxide and chlorine are obtained;

[0097] The temperature of the sixth condenser is -40°C, and liquid chlorine and carbon dioxide gas are obtained, and the liquid chlorine is recycled.

[0098] (6) The liquid niobium chloride and tantalum chloride mixture is introduced into a special distillation tower with a top temperature of 245.5° C., a bottom temperature of 250.5° C., a reflux ratio of 2, and a theoretical plate number of 100; the top produced liquid is 99.99% tantalum chloride, and the bottom produced liquid is 99.99% niobium chloride.

[0099] (7) High-temperature reduction of niobium chloride and tantalum chloride to obtain metallic niobium and metallic tantalum; wherein the volume ratio of niobium chloride to hydrogen is 1:3, and the reduction temperature is 1250°C; the volume ratio of tantalum chloride to hydrogen is 1:3, and the reduction temperature is 1250°C, to obtain pure metals of niobium and tantalum with a purity of 99.99%; the mixed gas after the reaction is absorbed by water, and the volume ratio of gas to water is 1:10; the absorbed aqueous solution is hydrochloric acid, which can be used for recycling, and the hydrogen is used in step (7) after dehydration.

[0100] Example 4

[0101] The method for separating and extracting niobium-tantalum concentrate in this embodiment comprises the following steps:

[0102] (1) tantalum concentrate and sodium hydroxide are ground to 200 meshes in a mass ratio of 1:2 under dry conditions and then mixed to obtain a mixture;

[0103] (2) putting the mixture into a high-temperature calcining furnace and reacting it at 800° C. for 3 hours; dissolving the reaction product in water and washing it to neutrality, and filtering it to obtain a filter cake.

[0104] (3) The filter cake in step (2) is added with 2 times the mass of HCl, 0.5 mol / L hydrochloric acid, reacted for 10 h for acid washing, and filtered to obtain a mixed oxide precipitate containing 50% by mass of tantalum oxide.

[0105] (4) Grinding the niobium tantalum mixed oxide precipitate and coke to 200 mesh, mixing them in a mass ratio of 1:5 and fully drying them, reacting them with chlorine gas at a flow rate of 0.2 m / s for 1 hour in a circulating fluidized bed chlorination furnace at a reaction temperature of 1200° C. The circulating fluidized bed chlorination furnace comprises a cyclone separation device, a circulation device and a reaction device.

[0106] (5) The gas generated by the reaction is separated from the solid phase by a cyclone separator and then subjected to step condensation; wherein:

[0107] The temperature of the first condenser is 600℃, and high melting point dust and gaseous chloride are obtained. The high melting point dust is captured by bag dust removal, and after water washing, the unreacted tantalum oxide and coke are returned to the chlorination process for re-granulation and reaction;

[0108] The temperature of the second condenser is 306°C, and a small amount of solid ferric chloride and gaseous chloride are separated;

[0109] The temperature of the third condenser is 249°C, which produces liquid tantalum chloride with higher purity and other gaseous chlorides;

[0110] The temperature of the fourth condenser is 220°C, and a small amount of solid tantalum chloride mixture and gaseous chloride are obtained;

[0111] The temperature of the fifth condenser is 130°C, and liquid titanium tetrachloride, as well as a mixture of carbon dioxide and chlorine are obtained;

[0112] The temperature of the sixth condenser is -35°C, and liquid chlorine and carbon dioxide gas are obtained, and the liquid chlorine is recycled.

[0113] (6) Passing a relatively high purity liquid tantalum chloride mixture into a specially designed distillation tower with a tower top temperature of 243° C., a tower bottom temperature of 280° C., a reflux ratio of 2.5, and a theoretical plate number of 100; the top produced liquid is high-purity tantalum chloride with a purity of 99.9999%.

[0114] (7) High-temperature reduction of tantalum chloride to obtain metallic tantalum. The volume ratio of tantalum chloride to hydrogen is 1:1.5, and the reduction temperature is 1500°C, to obtain pure tantalum metal with a purity of 99.9999%; the mixed gas after the reaction is absorbed by water, and the volume ratio of gas to water is 1:10; the absorbed aqueous solution is hydrochloric acid, which can be used for recycling, and the hydrogen is used in step (7) after dehydration.

[0115] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention; therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A chlorine-alkali coupled niobium-tantalum chlorination distillation separation and purification method, characterized in that: The following steps are involved: (1) mixing sodium hydroxide and niobium-tantalum concentrate and grinding them to obtain a mixture; (2) putting the mixture into a high-temperature calcining furnace for high-temperature reaction, dissolving the product in water after sufficient reaction, washing with water until neutral, and filtering to obtain a filter cake; (3) acid-washing and filtering the filter cake in step (2) to obtain a niobium-tantalum mixed oxide precipitate; (4) grinding and crushing the niobium-tantalum mixed oxide precipitate and the coke respectively, mixing them, adding them to a circulating fluidized bed chlorination furnace to fully react with chlorine gas to obtain gaseous chloride; (5) Gaseous chlorides are condensed in stages to obtain a mixture of niobium chloride and tantalum chloride; (6) passing the mixture of niobium chloride and tantalum chloride into a distillation tower for high-temperature distillation, separation and purification to obtain pure niobium chloride and pure tantalum chloride; (7) The niobium chloride and tantalum chloride obtained by distillation are further reduced by hydrogen to obtain niobium and tantalum metals with a purity of 99.99%-99.9999%.

2. The chlorine-alkali coupled niobium-tantalum chlorination distillation separation and purification method according to claim 1, characterized in that: The concentrate in step (1) contains one or both of niobium and tantalum elements, and the mass ratio of the concentrate to sodium hydroxide is 1:0.5 to 1:

5.

3. The chlorine-alkali coupled niobium-tantalum chlorination distillation separation and purification method according to claim 1, characterized in that: In step (2), the temperature of the high temperature calcining furnace is maintained at 500°C to 800°C.

4. The chlorine-alkali coupled niobium-tantalum chlorination distillation separation and purification method according to claim 1, characterized in that: In step (3) pickling, the mass ratio of hydrochloric acid to filter cake is 1:1 to 10.

5. The chlorine-alkali coupled niobium-tantalum chlorination distillation separation and purification method according to claim 1, characterized in that: In step (4), the particle size after grinding is 100-300 mesh, the mass ratio of niobium tantalum oxide to coke is 1:1-3, the chlorination reaction temperature is 700-1500° C., the chlorine gas flow rate is 0.1-0.2 m / s, and the reaction time is 1-2 h.

6. The chlorine-alkali coupled niobium-tantalum chlorination distillation separation and purification method according to claim 1, characterized in that: In step (4), the circulating fluidized bed chlorination furnace comprises a cyclone separation device, a circulation device and a reaction device.

7. The chlorine-alkali coupled niobium-tantalum chlorination distillation separation and purification method according to claim 1, characterized in that: In step (5), the step condensation temperature is set to: 450-600°C in the first stage; Second section: 255~306℃; third section: 225~249℃; fourth section: 136~220℃; fifth section: -25~130℃; sixth section: -50~-35℃.

8. The chlorine-alkali coupled niobium-tantalum chlorination distillation separation and purification method according to claim 1, characterized in that: In step (6), the bottom temperature is 254-280° C., the top temperature is 243-253° C., the reflux ratio is 1-4, and the number of theoretical plates is 100-150.

9. The chlorine-alkali coupled niobium-tantalum chlorination distillation separation and purification method according to claim 1, characterized in that: In step (7), hydrogen is used for reduction, and the reduction temperature is 1000-1500°C.

10. The chlorine-alkali coupled niobium-tantalum chlorination distillation separation and purification method according to claim 1, characterized in that: The hydrogen and hydrogen chloride mixed gas obtained after reduction in step (7) is absorbed by water, the hydrochloric acid obtained by the reaction of hydrogen chloride and water is used in step (3), and the hydrogen is used in step (7) after dehydration.