Method of fabrication of tantalum or niobium powder

FIELD: metallurgy.

SUBSTANCE: method includes heating of charge, containing oxygenous or oxygenous and oxygen-free composition of tantalum or niobium and halogenide of alkali metal with formation of melt. Into melt it is introduced alkali metal at blending and it is implemented reduction of tantalum or niobium at temperature 550-850°C. Additionally amount of oxygen in melt is regulated by means of changing of ratio of components of harge according to relation where n(O) - amount of oxygen, mol, k - empirically determined coefficient, k=60-350 mol, m1 and M1 - mass and molar mass of oxycompound of tantalum or niobium correspondingly in kg and kg/mol, m2 and M2 - mass and molar mass of oxygen-free composition of tantalum or niobium correspondingly in kg and kg/mol, m3 and M3 - mass and molar mass of alkali metal halogenide correspondingly in kg and kg/mol.

EFFECT: increased purity of powder, increasing of its specific surface area.

5 cl, 1 tbl, 7 ex

 

The invention relates to ferrous metallurgy and can be used in metallothermic the production of high-purity powders of tantalum and niobium with a large specific surface for the production of anodes texturized capacitors.

Anodic oxides of tantalum and niobium have a high dielectric characteristics and unilateral conductivity, due to which they belong to the category of valve metals. The anodes of the capacitors are made by pressing powder of a valve metal and sintering the preform in the furnace followed by the application of anodic oxide dielectric film polarization in solutions. The quality of the powder is determined by the value of its specific surface area and chemical composition, as the capacity of the anode of the capacitor at a given voltage proportional to the magnitude of its surface, and the content of impurities in excess of the maximum allowable level, causes significant degradation of the dielectric film, which leads to increased leakage current and reduction of the breakdown voltage. In the production of capacitors, typically use a powder of a valve metal with a large specific surface. These powders usually get metallothermic recovery of fortuntate or ferroniobata potassium. The need for a metal with a low content of impurities requires use of the project for a pure reagents. However, this leads to the formation of powders having insufficiently high specific surface area. The surface of the powders can be increased by optimizing the conditions for the restoration of a valve metal by microalloying of the charge or melt compounds comprising elements such as boron, nitrogen, sulfur or phosphorus.

A method of obtaining powder of tantalum (see U.S. patent No. 4645533, MKI4C22F 9/24, 1987), including loading in the reaction vessel mixture containing ftorotane potassium (K2TaF7), a halide of an alkali metal and at least one alloying additive selected from the group comprising boron and/or phosphorous component, mainly in the form of compounds: P2O5, CA3(PO4)2H3PO4N3IN3, KBF4, NH4BO3, Na3BO3B2O3, NH4BF4, NaBF4. The content in the charge of boron or phosphorus in relation to the metal tantalum is (0,1-6,0)×10-2wt.%. Next melt the mixture and the resulting melt continuous stirring injected alkali metal, preferably sodium. The reaction mass is then cooled to room temperature, pulverized and washed derived tantalum powder from other salts. The doping can be carried out at the stage of obtaining fortuntate Kali is by introducing the above boric and phosphoric compounds in the mother liquor, used for crystallization K2TaF7. Anodes texturized capacitors made from the obtained powders have the highest specific charge 13600 µc/g at sintering temperature of 1600°C.

The disadvantage of this method is the pollution of the obtained powders of metal impurities entering the melt due to corrosion of the material of the reaction vessel. The most intensively corrosion occurs during the melting of the charge in the active interaction of the resulting melt with the material of the reaction vessel. Another disadvantage is that the anodes of capacitors made from these powders have a low specific charge, due to the low specific surface of powders. The presence in the melt of boron and other alloying elements, aimed to increase the specific surface of the powder leads to their capture of tantalum, which causes degradation of the anodic oxide dielectric film, resulting the increase of the leakage current and a decrease in the breakdown voltage of the capacitor.

Also known is a method of obtaining powder of tantalum or niobium (see RF patent №2284248, IPC B22F 9/18 (2006.01), 2006), including loading in the reaction vessel mixture containing oxygen or oxygen and oxygen-free compounds of tantalum or niobium halide of the alkali metal on the matter, potassium or mixtures thereof in the form of its chloride and/or fluoride and alloying additive in the form of one or more elements selected from the group comprising sulfur, phosphorus, nitrogen. Each of these elements take in the amount of 0.005 to 0.2% by weight of compounds of tantalum or niobium, with predominantly use sulfur as it contributes to the greatest increase of the specific surface of the powder. After loading the mixture is heated to form a melt, is introduced into the molten alkaline metal when mixed with the recovery of tantalum or niobium, cool the resulting reaction mass and washed the resulting powder of tantalum or niobium from the halides of the alkali metal. To protect the reaction vessel from corrosion using a layer of a halide of an alkali metal, which is formed on the inner surface of the vessel, and the mixture is loaded into the reaction vessel in such a way that it is limited to a protective layer of alkali metal halide. Thus there is a significant decrease in the content in the powder metal components present in the material of the reaction vessel. The resulting powders have a specific surface area of 0.98-1.95 m2/year Specific charge made of them anodes texturized capacitors is 45560-60800 µc/g at sintering temperature of 1400°C.

The disadvantage of this method is that the resulting p is Rosca have a relatively low specific surface area and consequently insufficiently high specific charge made of them anodes. The presence in the mixture of alloying elements in the form of sulfur, nitrogen and/or phosphorus, aimed at a further increase of the specific surface of the powder leads to capture these elements tantalum or niobium, which causes degradation of the anodic oxide dielectric film, resulting the increase of the leakage current and a decrease in the breakdown voltage of the capacitor.

The technical result of the method according to the invention is to improve the quality of the powder of tantalum or niobium, which increases the breakdown voltage and specific charge texturized capacitors by increasing the purity of the powder and increase its specific surface area.

The technical result is achieved in that in the method of producing powder of tantalum or niobium, including loading in the reaction vessel mixture containing oxygen or oxygen and oxygen-free compounds of tantalum or niobium and a halide of an alkali metal, heating the mixture to form a melt, introducing a melt of an alkali metal with stirring, the recovery of tantalum or niobium, cooling the reaction mixture and washing powder of tantalum or niobium from the halides of the alkali metal, according to the invention the amount of oxygen in the melt regulate by changing the component ratio of the mixture according to:

where n(O) - the amount of oxygen, mol,

k is an empirical coefficient, k=60-350 mol,

m1, M1mass and molar mass of oxygen compounds of tantalum or niobium, respectively, in kg and kg/mol,

m2, M2mass and molar mass of oxygen-free compounds of tantalum or niobium, respectively, in kg and kg/mol,

m3, M3mass and molar mass of the alkali metal halide, respectively, in kg and kg/mol, and the recovery of tantalum or niobium is carried out in the temperature range 550-850°C.

The achievement of the technical result is driven by the fact that, as the oxygen compounds of tantalum or niobium is used as a compound selected from the group consisting of K2MeO2F5, K3MeOF6, K2Me2O3F6, KMeOF4, K2MeO2F3, K3MeOF5Cl, K2NaMeOF5Cl, Me2O5where Me is TA or Nb.

The achievement of the technical result also contributes to the fact that as oxygen-free compounds of tantalum or niobium is used K2MeF7or Na2MeF7where Me is TA or Nb.

The achievement of the technical result is also that as an alkali metal is used, the sodium, potassium or a mixture.

The achievement of the technical result is strengthened by the fact that as the halide of the alkali metal is sportsouth its chloride and/or fluoride.

The essential features of the claimed invention, defining the scope of legal protection and sufficient to obtain the above-mentioned technical result function and correlate with the results as follows.

The presence of oxygen in the melt leads to the formation of refractory oxide compounds of tantalum or niobium, which is a separate fine phase, which can generate additional centers of crystallization of the powder particles. In addition, the oxygen in the melt promotes passivation faces growing crystallites of the metal. To create the most favorable conditions for the restoration of powder, it is desirable that the amount of oxygen added to the charge, answered according to (1). While the number of oxygen or oxygen and oxygen-free compounds of tantalum or niobium and halides of alkali metals used in one cycle of recovery, may be two or more taking into account the preferred groups of compounds of tantalum: K2TaO2F5, K3TaOF6, K2Ta2O3F6, KTaOF4, K2TaO2F3, K3TaOF5Cl, K2NaTaOF5Cl, Ta2O5, K2TaF7and Na2TaF7or compounds of niobium: K2NbO2F5, K3NbOF6, K2Nb2O3F6, KNbOF4/sub> , K2NbO2F3, K3HbOF5Cl, K2NaNbOF5Cl, Nb2O5, K2NbF7and Na2NbF7and halides of alkali metals: NaCl, KCl, KF and NaF. The empirical coefficient k=60-350 mol depends on the physical and physico-chemical characteristics of reagents used, in particular their surface tension. This is because when reconnecting tantalum or niobium sodium, potassium or a mixture of the resulting metal particles are retained in the reaction zone by the force of surface tension. When the gravitational force acting on the particle, becomes larger than the surface tension force, it leaves the reaction zone and the growth of the powder particles is terminated. Therefore, the higher the surface tension of the melt, the larger particles and therefore less specific surface area of the obtained powder. The magnitude of the surface tension in melts containing halides of alkali metals increases with decreasing size of the cations or anions, as well as with increasing ratio of the charge of an ion to its radius. Thus, at one and the same cation composition of the halides of the alkali metal surface tension of the melt will increase during the transition from the chloride-fluoride melts to a purely fluoride. With this in mind, when using as halide, alkaline is on metal chloride choose the value of the coefficient k, close to the lower limit of 60 mol, and when used as the halide of the alkali metal fluoride to the upper limit of 350 mol. When the coefficient is less than 60 mol of oxygen in the melt is not sufficient for the creation of a significant number of additional centers of crystallization of the particles, and passivation faces growing crystallites of metal, and when the value of the coefficient of more than 350 mol oxygen content in the metal may exceed the permissible level. All this reduces the quality of the powder.

The recovery of tantalum or niobium in the temperature range 550-850°C helps to increase the purity of the powder and increase its specific surface area. When the temperature drops below 550°C will be partial crystallization of the melt and result in incomplete recovery of salts of tantalum or niobium with the formation of poorly soluble salts, which makes it difficult to wash from them powder of tantalum or niobium. The presence of such salts in powder leads to degradation of the dielectric anodic film and thus to reduce the breakdown voltage in the finished product. At temperatures above 850°C is the consolidation of the powder, thus reducing its specific surface area. In addition, at high temperature increases the diffusion interaction between the walls of the reaction vessel, on the one hand, and melt and Sol the new pairs above the melt, on the other hand, which causes contamination of the powder of tantalum or niobium metal components present in the material of the vessel.

The combination of the above features is necessary and sufficient to achieve the technical result of the invention to increase the purity of the powder of tantalum or niobium and the increase in its specific surface area, which improves the quality of the powder, provides an increase in the breakdown voltage and specific charge texturized capacitors.

In some cases, of the preferred embodiment of the invention the following specific operations and operational parameters.

Use as oxygen compounds of tantalum or niobium of one or more compounds selected from the group consisting of K2MeO2F5, K3MeOF6, K2Me2O3F6, KMeOF4, K2MeO2F3, K3MeOF5Cl, K2NaMeOF5Cl, Me2O5and as oxygen-free compounds of tantalum or niobium - K2MeF7or Na2MeF7(where Me - TA or Nb), allows for a controlled introduction of oxygen in the charge or melt while ensuring full recovery of the alkali metal as the above compounds and decomposition products, as well as compounds of tantalum or niobium, which is formed in the reaction suck the e in the result of the interaction between the components of the mixture prior to introduction into the melt of an alkali metal. It contributes to the formation of the reaction mixture not containing water-insoluble salts, which improves the quality of the powder of tantalum or niobium, while maintaining its purity.

The use of sodium, potassium or mixtures thereof as alkali metal allows after the recovery of tantalum or niobium to obtain a mixture of salts, are well soluble in water, which provides a low content of alkali metals in the powder. Along with sodium and/or potassium as the alkali metal can be used as lithium, rubidium, cesium or mixtures thereof. However, after the recovery of lithium, a mixture of lithium to caesium and/or rubidium form less soluble salts, which complicates the hillshade derived from them powder of tantalum or niobium. Recovery caesium allows you to obtain a mixture of salts, are well soluble in water. However, cesium compared to sodium and potassium is a more expensive material, which leads to a significant increase in the cost of production of powder.

The use of a halide of an alkali metal in the charge of its chloride and/or fluoride reduces the melting temperature, to reduce the viscosity of the melt and get after recovering the mixture of salts, soluble in water, which contributes to obtaining a powder having a low content of alkali metals. is long with chloride and/or fluoride as the halide of the alkali metal can be used bromide and/or iodide. However, compared to the chlorides and fluorides of these halides are more expensive, which increases the cost of production of powder.

The above private features of the invention allow a method in an optimal manner and to obtain the powder of tantalum or niobium of high purity with increased specific surface area, which ensures an increase in the breakdown voltage and specific charge texturized capacitors.

In General, the method of obtaining powder of tantalum or niobium according to the invention is as follows. In cylindrical Nickel reaction vessel load the mixture in the form of individual components or in the form of a homogeneous mixture of oxygen compounds of tantalum or niobium K2MeO2F5, K3MeOF6, K2Me2O3F6, KMeOF4, K2MeO2F3, K3MeOF5Cl, K2NaMeOF5Cl or Me2O5(where Me - TA or Nb) and alkali metal halide MR (where M Is Na, K; R is Cl, F). Reagents are of high purity (GC). The formation of a homogeneous mixture of these oxygen compounds of tantalum or niobium and alkali metal halide and an oxygen-free compounds of tantalum or niobium K2MeF7or Na2MeF7(where Me - TA or Nb). The above oxygen compounds of tantalum or SRO of the Oia can be directly loaded into the reaction vessel, and be formed after loading and heating of the charge in the decomposition of the original oxygen compounds or due to its chemical interaction with oxygen-free compound of tantalum or niobium. The amount of oxygen in the melt regulate by changing the component ratio of the mixture according to (1), the specific value of the empirical coefficient k=60-350 mol choose with regard to physical and physico-chemical characteristics of oxygen and oxygen-free compounds of tantalum or niobium, as well as alkali metal halide. After the download has completed, the reaction vessel sealed vacuum to a residual pressure of 1-3 PA in the process of heating the mixture to a temperature of 450°C, filled with inert argon gas, melt the batch and continuous mixing of the liquid serves alkali metal (sodium, potassium or a mixture thereof) in an amount of 2-5 wt.% in excess of the stoichiometric required for full recovery of tantalum or niobium at a temperature of 550-850°C. followed by cooling the reaction vessel to room temperature, remove the reaction mass, grind it, and the obtained powder of tantalum or niobium is rinsed with deionized water from the halides of the alkali metal. The water consumption depends on the amount of the halides of the alkali metal in the reaction mass, and their soluble the tee. Washed from salt powder is treated consistently in the solution model HC1 and HF aqueous solution, then washed with deionized water and dried.

In the salts washed from the powders by the method iodometric titration, with a detection limit of 0.007 wt.%, control the sulfur content as the main alloying elements. For process testing of powders of them pressed anodes with a diameter of 2.95 mm and a density of 4.5 g/cm3that is sintered in vacuum resistance furnace for 30 min at a residual pressure of not more than 5·10-5PA and a temperature of 1300°C. the Formation of tantalum and niobium anodes are respectively 0.1% and 1% solution of phosphoric acid at a temperature of 80°C and 60°C, maintaining a constant current density 90-120 mA/g until the voltage 30 V, followed by exposure at this voltage for 3 hours capacity Measurement is carried out in 38% sulfuric acid solution at a frequency of 50 Hz with AC current bridge. The breakdown voltage was measured in 0.1% solution of orthophosphoric acid at a temperature of 90°C.

The nature and advantages of the invention can be illustrated by the following examples of embodiment of the invention.

Example 1. In the reaction vessel loads powder charge containing being 9.61 kg of salt oxygen compounds of tantalum K3TaOF5Cl (molar mass of 0.37 kg/mol) and 4.8 kg of potassium chloride KCl (molar mass 0,0745 kg/mol). The value of the empirical coefficient k=66 mol, which corresponds to the amount of oxygen in the melt n(O)=21.6 mol. After the batch charging the reaction vessel is sealed and vacuum up to a pressure of 1 PA in the process of heating up to 450°C. after evacuating the reaction vessel is filled with argon, heated to 690°C, kept at this temperature until the melting of the charge and under continuous stirring for 1 h serves liquid sodium in the amount of 2.54 kg, gradually increasing the melt temperature to 820°C. followed by cooling the reaction vessel to room temperature, the reaction mass in the number 16,98 kg extract, crushed to particle size of not more than 1 mm and the resulting tantalum powder is rinsed with deionized water from salts, which take, respectively, in the amount of 4.7 l/kg reaction mass. Washed from salt powder is treated consistently in a solution of 10% HCl and 1% HF aqueous solution, which take, respectively, in the amount of 1.0 and 0.5 l/kg of the powder, and then thoroughly washed with deionized water and dried. The resulting powder has a specific surface area of 2.9 m2/year / Unit charge is 65300 µc/g at sintering temperature of 1300°C. the sulfur Content in the powder below the detection limit. The composition of the reagents and characterization of tantalum powder obtained in Example 1, and the powders obtained by the Use of the s 2 to 6 and Example 7 of the prototype, shown in the Table.

Example 2. In the reaction vessel loads powder charge containing 6.0 kg salt oxygen compounds of niobium K2NbOF5(molar mass 0,282 kg/mol) and 3,50 kg of NaCl (molar mass 0,0585 kg/mol). The value of the empirical coefficient k=60 mol, which corresponds to the amount of oxygen in the melt n(O)=21,3 mol. After the batch charging the reaction vessel is sealed and vacuum up to a pressure of 1 PA in the process of heating up to 450°C. after evacuating the reaction vessel is filled with argon, heated to 550°C, kept at this temperature until the melting of the charge and under continuous stirring for 1 h serves liquid potassium in number to 4.23 kg, gradually increasing the melt temperature to 800°C. followed by cooling the reaction vessel to room temperature, the reaction mass in the number 13,73 kg extract, crushed to particle size of not more than 1 mm and the obtained niobium powder is rinsed with deionized water from salts, which take, respectively, in the amount of 5.5 l/kg reaction mass. Washed from salt powder is treated consistently in a solution of 10% HCl and 1% HF aqueous solution, which take, respectively, in the amount of 1.0 and 0.5 l/kg of the powder, and then thoroughly washed with deionized water and dried.

Example 3. In the reaction vessel load powder ¾ the hut, containing 8 kg of salt oxygen compounds of tantalum K2TaO2F5(molar mass 0,386 kg/mol), 1.56 kg of sodium fluoride NaF (molar mass 0,042 kg/mol) and of 3.69 kg of NaCl (molar mass 0,0585 kg/mol). After the batch charging the reaction vessel is sealed and vacuum up to a pressure of 1 PA in the process of heating up to 450°C. When the decomposition of salts of K2TaO2F5with the formation of 3.12 kg oxygen compounds of tantalum K3TaOF6and of 4.44 kg of oxygen compounds of tantalum K2Ta2O3F6. The value of the empirical coefficient k=l70 mol, which corresponds to the amount of oxygen in the melt

n(O)=25,9 mol. After evacuating the reaction vessel is filled with argon, heated to 730°C, kept at this temperature until the melting of the charge and under continuous stirring for 0.9 hours serves a liquid mixture consisting of sodium in the amount of 1.2 kg and potassium quantity 2,04 kg, gradually increasing the melt temperature to 850°C. followed by cooling the reaction vessel to room temperature, the reaction mass in the amount of 12.8 kg extract, crushed to particle size of not more than 1 mm and the resulting tantalum powder is rinsed with deionized water from salts, which take, respectively, in the amount of 8.5 l/kg reaction mass. Washed from salts powder process PEFC is therefore in a solution of 10% HCl and 1% HF aqueous solution, taken respectively in the amount of 1.0 and 0.5 l/kg of powder, and then thoroughly washed with deionized water and dried.

Example 4. In the reaction vessel loads powder charge containing 2 kg of salt oxygen compounds of K2TaO2F3(molar mass 0,348 kg/mol), 6 kg of salt anoxic tantalum compounds K2TaF7(molar mass 0,392 kg/mol) and 13,15 kg of potassium fluoride KF (molar weight 0,058 kg/mol). The value of the empirical coefficient k=350 mol, which corresponds to the amount of oxygen in the melt n(O)=34.5 mol. After the download has completed, the reaction vessel sealed vacuum to a residual pressure of 2 PA in the process of heating to a temperature of 450°C, filled with argon, heated to 750°C, kept at this temperature until the melting of the charge and under continuous stirring for 1 h serves liquid sodium in the amount of 2.46 kg, gradually increasing the melt temperature to 850°C. followed by cooling the reaction vessel to room temperature, the reaction mass in the amount of 25.5 kg extract, crushed to particle size of not more than 1 mm and the resulting tantalum powder is rinsed with deionized water from salts, which respectively take in the amount of 6.5 l/kg reaction mass. Washed from salt powder is treated consistently in a solution of 10% HCl and 1% HF aqueous solution, which charge is respectively in the amount of 1.0 and 0.5 l/kg powder, then thoroughly washed with deionized water and dried.

Example 5. In the reaction vessel loads powder charge containing 2 kg of salt oxygen compounds of K2NbOF5(molar mass 0,282 kg/mol), 6 kg of salt oxygen compounds of K2NaNbOF5Cl (molar mass 0,3405 kg/mol), 1 kg of salt oxygen-free compounds of niobium Na2NbF7(molar mass 0,272 kg/mol), 6.3 kg of potassium chloride KCl (molar mass 0,0745 kg/mol) and 4,7 kg of potassium fluoride KF (molar weight 0,058 kg/mol). The value of the empirical coefficient k=144 mol, which corresponds to the amount of oxygen in the melt

n(O)=24,7 mol. After the download has completed, the reaction vessel sealed vacuum to a residual pressure of 2 PA in the process of heating to a temperature of 450°C, filled with argon, heated to 620°C, kept at this temperature until the melting of the charge and under continuous stirring for 0.9 hours serves liquid sodium in the number 3.36kg, gradually increasing the melt temperature to 830°C. followed by cooling the reaction vessel to room temperature, the reaction mass in the number 23,36 kg extract, crushed to particle size of not more than 1 mm and the obtained niobium powder is rinsed with deionized water from salts, which respectively take 8 l/kg reaction mass. Washed from salts powder processed is t analogously to Example 1 and dried.

Example 6. In the reaction vessel loads powder charge containing 2.65 kg of tantalum pentoxide, niobium Ta2O5(molar mass 0,442 kg/mol), 7,06 kg of salt anoxic tantalum compounds K2TaF7(molar mass 0,392 kg/mol) and at 5.27 kg of NaCl (molar mass 0,0585 kg/mol). After the download has completed, the reaction vessel sealed vacuum to a residual pressure of 2 PA in the process of heating to a temperature of 450°C, filled with argon, heated to 750°C, kept at this temperature until the melting of the charge. During melting as a result of chemical interaction between the K2TaF7and Ta2O5in the melt is formed 8,42 kg oxygen compounds KTaOF4and 1.28 kg oxygen compounds of K3TaOF6. The value of the empirical coefficient k=112,5 mol, which corresponds to the amount of oxygen in the melt n(O)=30 mol. After melting the mixture, the melt is stirred for 5 min, and then stopping stirring, in the course of 0.85 h serves liquid sodium in the number of 3.46 kg, gradually increasing the melt temperature to 850°C. followed by cooling the reaction vessel to room temperature, the reaction mass in the number 18,44 kg extract, crushed to particle size of not more than 1 mm and the resulting tantalum powder is rinsed with deionized water from salts, which take proper is about 9 l/kg reaction mass. Washed from salt powder is treated analogously to Example 1 and dried.

Example 7 (the prototype). In the reaction vessel loads powder charge containing 1 kg of salt oxygen compounds of K3TaOF6, 8 kg of salt oxygen-free connection of a valve metal K2TaF7and 8 kg of sodium chloride is NaCl. In the sodium chloride pre-enter alloying additive in the form of sodium sulfate Na2SO4in the amount of 40 g, which corresponds to a sulfur content of 0.1% by weight of a loaded connection of a valve metal. After the download has completed, the reaction vessel sealed vacuum to a residual pressure of 3 PA in the process of heating to a temperature of 450°C, filled with argon, heated to 750°C, kept at this temperature until the melting of the charge and under continuous stirring for 0.9 hours serves liquid sodium in the amount of 2.7 kg, gradually increasing the melt temperature to 830°C. followed by cooling the reaction vessel to room temperature, the reaction mass in an amount of 19.7 kg extract, crushed to particle size of not more than 1 mm and the resulting tantalum powder is rinsed with deionized water from salts, which take into 8 l/kg reaction mass. Washed from salt powder is treated consistently in a solution of 10% HCl and 1% HF aqueous solution, which take, respectively, in the amount of 1.0 and 05 l/kg powder, then thoroughly washed with deionized water and dried. The resulting powder has a specific surface area of 1.95 m2/year / Unit charge is 57600 µc/g at sintering temperature of 1300°C. the sulfur Content in the powder being 0.036 wt.%.

From the above Examples and the Table shows that the proposed method compared with the prototype to improve the purity of the powder of tantalum or niobium due to the exclusion of sulfur and other alloying elements and to increase the value of specific surface area 1.5-2 times. The specific charge of the anode increases

20-30%, and the breakdown voltage is increased by 14-18%.

1. The method of obtaining powder of tantalum or niobium, including loading in the reaction vessel mixture containing oxygen or oxygen and oxygen-free compounds of tantalum or niobium and a halide of an alkali metal, heating the mixture to form a melt, introducing a melt of an alkali metal with stirring, the recovery of tantalum or niobium, cooling the reaction mixture and washing powder of tantalum or niobium from the halides of the alkali metal, wherein the amount of oxygen in the melt regulate by changing the component ratio of the mixture according to

where n(O) is the number of oxygen moles;
k is an empirical coefficient, k=60-350 the ol;
m1, M1mass and molar mass of oxygen compounds of tantalum or niobium, respectively, kg and kg/mol;
m2, M2mass and molar mass of oxygen-free compounds of tantalum or niobium, respectively, kg and kg/mol;
m3, M3mass and molar mass of the alkali metal halide, respectively, kg and kg/mol,
moreover, the recovery of tantalum or niobium is carried out in the temperature range 550-850°C.

2. The method according to claim 1, characterized in that as the oxygen compounds of tantalum or niobium is used as a compound selected from the group consisting of
K2MeO2F5, K3F6, K2IU2O3F6, KF4, K2MeO2F3, K3F5CL, K2NaMeOF5Cl, Me2O5where Me is TA or Nb.

3. The method according to claim 1 or 2, characterized in that the oxygen-free compounds of tantalum or niobium is used K2F7or PA2F7where Me is TA or Nb.

4. The method according to claim 1, characterized in that the alkali metal used sodium or potassium, or a mixture.

5. The method according to claim 1 or 4, characterized in that the alkali metal halide used its chloride and/or fluoride.



 

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8 cl, 5 ex

FIELD: metallurgy.

SUBSTANCE: method includes sodium-reduced reduction of potassium fluorine- tantalat while its fractional or continuous batching into alloyed sodium. Reduction is implemented at the temperature from 400 till 600°C and ratio sodium / potassium fluorine- tantalat from 5 till 10. Facility contains heated reaction vessel with cover, degassing system, letting in and exhaust of argon, control system and keeping of pressure of argon inside the facility. It is additionally outfitted by joint by means of pipeline for sodium movement with reaction vessel with the second heated vessel with beveled bottom and allowing cover with facility of sodium charge, connecting pipe of sodium feeding and degassing and connecting pipe of sodium discharge. At that reaction vessel is implemented with beveled bottom and has implemented as perforated storage tank of reduced product. Cover of reaction vessel is outfitted by charging connecting pipe of potassium fluorine- tantalat.

EFFECT: powder improvement, cost saving, design simplification and its running.

7 cl, 1 dwg, 1 ex

FIELD: metallurgy.

SUBSTANCE: invention concerns rare-metal industry. Particularly it concerns receiving of metallic tantalum by metallothermic reduction of its salts. For receiving of metallic tantalum charge, containing mixture of double complex chloride salt of tantalum - KTaCl6 and potassium chloride - KCl in ratio 1:(0.2÷0.5) by mass are fed by portions or uninterruptedly in the form of powder or melt on melt mirror of metallic sodium, taken in excess 60-80% of stoichiometrically necessary amount. Reduction is implemented at temperature 550-650°C, with speed of charge feeding 15-20 g/cm2·hour of area melt mirror of metallic sodium melt. Received reduced reactionary mass is subject to vacuum- thermal processing at temperature 500-540°C and residual pressure, not exceeding equilibrium pressure of sodium steams at temperature of vacuum- thermal processing of unreacted sodium. After vacuum- thermal processing it is implemented hydro metallurgical treatment of reactionary mass.

EFFECT: exclusion of ecological pollution of environment.

4 cl, 2 tbl, 2 ex

FIELD: metallurgy.

SUBSTANCE: invention refers to powder metallurgy, particularly to method and device for production of tantalum powder of high chemical purity; suggested powder can be utilised at production of condensers. The method consists in sodium-reduced reduction of potassium fluor-tantalate by means of batched or continuous dosing of potassium fluor-tantalate. Also reduction is performed at free fall of potassium fluor-tantalate crystals in the medium of inert gas and sodium vapors. The device contains a furnace heated reaction vessel with a cover and a sleeve for sodium charge, a system of degassing, intake and exhaust of argon, a system of control and maintaining of inert gas pressure inside the device. The device is equipped with condenser of excessive sodium connected to the reaction vessel. The reaction vessel is made in form of a vertical retort with ratio of diameter/height within ranges from 0.15 to 0.30, height over 800 mm and diameter over 200 mm with an expander in the upper part forming a circular chute. It contains a perforated collector of reduced product. The cover of the reaction vessel is made conic and is equipped with a potassium fluor-tantalate charge sleeve. The heating furnace of the reaction vessel is equipped with the sodium evaporation zone and zone of maintaining sodium in vaporous state.

EFFECT: eliminating tantalum powder contamination with reactor material impurities and also reduction of cost.

2 cl, 1 dwg, 1 tbl, 1 ex

FIELD: metallurgy.

SUBSTANCE: method includes reduction of fluorine tantalite of potassium with liquid sodium in medium of melted saline bath of halogenides of alkali metals by means of alternate portioned dozing of sodium, and further - of fluorine tantalite of potassium. Fluorine tantalite of potassium is introduced into mixtures with part of the charge of halogenides of alkali metals, used for making of a saline bath. Amount of halogenides of alkali metals in the mixture introduced into melt with fluorine tantalite of potassium constitutes from 60 to 125% (wt) from weight of fluorine tantalite of potassium.

EFFECT: dimension in size of powder particles, reduction of duration of reduction process, decreasing of power consumption for melting of saline charge and forced cooling of reaction vessel.

1 tbl, 1 ex

FIELD: metallurgy.

SUBSTANCE: invention refers to extraction and concentration of thorium out of process waste of loparit concentrates treatment - spent melt of saline sprinkler filter (SSF) of loparit concentrate chlorination process. The method includes preparation of suspension by means of discharge of spent melt of saline sprinkler filter (SSF) into water, incorporation of high molecular flocculant, of holding, filtering, separation of sediment, obtaining of chloride solution, and of treatment with steel scrap and metal magnesium. Prior to obtaining chloride solution the source suspension is heated to 60-90°C and treated with solution of sodium hydroxide to pH 1.5-2.0 and to 0.1-0.3% solution of high molecular flocculant at amount of 3-5% from the source volume of suspension; then suspension is held for 2-4 hrs. Chloride solution is received by means of filtration of spent suspension obtaining sediment of rare metals; chloride solution is then treated with steel scrap and metal magnesium; at that the solution is successively treated first with the steel scrap at amount of 3-5 mass fractions of iron per 1 fraction of iron ions (III) in chloride solution at 80-100°C for 1-3 hrs till achieving the value of pH in a pulp equal to 3.0-3.5. Then the pulp is separated from the non-reacted portion of the steel scrap and is treated with metal magnesium to pH 3.5-4.5, and further with 0.1-0.3% solution of high molecular flocculant taken at amount of 5-20% from the volume of chloride solution. Thus produced pulp is held without mixing for 1-4 hrs and filtered producing thorium containing sediment; the said sediment is washed at filter first with solution containing 1-5 g/dcm3 of sodium sulphite, then with water. Washed out sediment is repulped in solution of sodium hydroxide with concentration of 50-150g/dcm3 at a ratio of "Ж:Т"=3-5 at 60-90°C for 2-3 hrs, after what the pulp is filtered with separation of alkaline filtrate. Thorium containing sediment at the filter is washed with water, pressed at the filter and dried; the alkaline filtrate and process water are merged and mixed, then heated to 80-90°C, and treated with solution of sodium hydroxide to pH 11-13 with production of hydroxide pulp. Hydroxide pulp is filtered and then radioactive sediment is produced at the filter; it is washed out with water and transferred to a special wastes depositary, while filtrate is mixed with 10-20 volumes of shop flush water, heated to 80-90°C and again treated with solution of sodium hydroxide to pH 11-13. Obtained pulp is held and filtered thus producing sediment of rare metals and deactivated chloride solution which is discharged to drainage. Sediment of rare metals is unloaded from the filter, merged with sediment of rare metals extracted from the source suspension, dried, washed out and then transferred for preparation of charge for its further chlorination together with the loparit concentrate.

EFFECT: upgraded efficiency of thorium extraction and simultaneously solving problem of neutralisation and utilisation of process waste.

1 dwg, 1 ex

FIELD: chemistry.

SUBSTANCE: group of inventions pertains to the metallurgy of rare metals, in particular to the method of chloric decomposition of polymetallic niobium-tantalum containing raw material with obtaining of chlorides of niobium and/or tantalum and a device (chlorinator) for carrying out the chlorination process. The method involves chlorinating polymetallic niobium and/or tantalum containing materials in molten chlorides using chlorine, condensation and separation of the obtained pentachlorides of niobium and/or tantalum and chlorides of admixtures and tapping of the melt. Chlorination is done in the layer of melt with height of 500-1000 mm, containing iron chloride (up to 25% iron) and/or copper (up to 40% copper), as well as sodium chloride in quantity of not less than 1.2 kg for 1 kg of iron and not less than 2.2 kg for 1 kg of aluminium in the initial materials. The process is carried out at 550-850°C with consumption of chlorine of 1.7-2.2 kg for 1 kg of the initial materials. Tapping of the melt is done from the upper level through a tapping line. The chlorinator is water cooled, lined with graphite and equipped with a separation chamber, located in the upper part of the chlorinator. The ratio of the diameter of the chlorinator to the diameter of the separation chamber is equal to (2÷2.5):3, and the ratio of their heights is (1÷2):1. There is a removable graphite pipe for supplying chlorine, which runs through a water cooled connection pipe, tightly joined to the cover of the chlorinator, to the bottom of the chlorinator. Tapping of the melt is done from the upper level through a heated tapping line, lined with graphite.

EFFECT: design of a efficient method of chloric decomposition of polymetallic niobium-tantalum containing raw materials with obtaining of chlorides of niobium and/or tantalum.

2 cl, 1 dwg, 3 ex

FIELD: non-ferrous metallurgy, possibly production of highly purified powders of tantalum and niobium with large specific surface by metal thermal reduction.

SUBSTANCE: method is realized at using as corrosion protection means layer of halide of alkali metal formed on inner surface of vessel before creating in reaction vessel atmosphere of inert gas. Charge contains valve metal compound and halide of alkali metal. It is loaded into reaction vessel and restricted by protection layer of halide of alkali metal having melting temperature higher than that of charge by 50 - 400°C. Before loading charge, valve metal compound and alkali metal halide may be mixed one with other. Mass of protection layer of alkali metal halide Ml and charge mass Mc are selected in such a way that that to satisfy relation Ml = k Mc where k - empiric coefficient equal to 0.05 - 0.5. Gas atmosphere of reaction vessel contains argon, helium or their mixture. Fluorotantalate and(or) oxyfluorotantalate or fluoroniobate and(or) oxyfluoroniobate of potassium is used as valve metal compound. Sodium, potassium or their mixture is used as alkali metal. Chloride and(or) fluoride is used as alkali metal halide. Valve metal compound and alkali metal halide may contain alloying additives of phosphorus, sulfur, nitrogen at content of each additive in range 0.005 - 0.1% and 0.005 - 0.2% of mass valve metal compound respectively. Invention lowers by 1.3 - 2 times contamination of powder with metallic impurities penetrating from vessel material. Value of specific surface of powder is increased by 1.2 - 1.8 times, its charge is increased by 10 - 30 %, leakage current are reduced by 1.2 - 1.5 times.

EFFECT: improved quality of valve metal powder, enhanced efficiency of process due to using heat separated at process of reducing valve metal for melting protection layer.

9 cl, 1 tbl, 4 ex

FIELD: metallurgy.

SUBSTANCE: double complex chlorides of ittrium and potassium is reduced by lithium at temperature 450-720°C in inert atmosphere and high pressure. Received reacting mass is heated at a rate 3-5°C/min up to the temperature for 60-300°C higher the reduction temperature and then it is implemented vacuum separation at a temperature 750-780°C and evacuation 1·10-4 millimetres of mercury.

EFFECT: it is provided receiving of microcrystalline metallic powder of itrrium with minimal content of oxygen and gas-producing admixtures, described by high dispersity.

5 cl, 1 tbl, 1 dwg, 1 ex

FIELD: metallurgy.

SUBSTANCE: invention concerns rare-metal industry. Particularly it concerns receiving of metallic tantalum by metallothermic reduction of its salts. For receiving of metallic tantalum charge, containing mixture of double complex chloride salt of tantalum - KTaCl6 and potassium chloride - KCl in ratio 1:(0.2÷0.5) by mass are fed by portions or uninterruptedly in the form of powder or melt on melt mirror of metallic sodium, taken in excess 60-80% of stoichiometrically necessary amount. Reduction is implemented at temperature 550-650°C, with speed of charge feeding 15-20 g/cm2·hour of area melt mirror of metallic sodium melt. Received reduced reactionary mass is subject to vacuum- thermal processing at temperature 500-540°C and residual pressure, not exceeding equilibrium pressure of sodium steams at temperature of vacuum- thermal processing of unreacted sodium. After vacuum- thermal processing it is implemented hydro metallurgical treatment of reactionary mass.

EFFECT: exclusion of ecological pollution of environment.

4 cl, 2 tbl, 2 ex

FIELD: metallurgy.

SUBSTANCE: method includes reduction of fluorine tantalite of potassium with liquid sodium in medium of melted saline bath of halogenides of alkali metals by means of alternate portioned dozing of sodium, and further - of fluorine tantalite of potassium. Fluorine tantalite of potassium is introduced into mixtures with part of the charge of halogenides of alkali metals, used for making of a saline bath. Amount of halogenides of alkali metals in the mixture introduced into melt with fluorine tantalite of potassium constitutes from 60 to 125% (wt) from weight of fluorine tantalite of potassium.

EFFECT: dimension in size of powder particles, reduction of duration of reduction process, decreasing of power consumption for melting of saline charge and forced cooling of reaction vessel.

1 tbl, 1 ex

FIELD: metallurgy.

SUBSTANCE: invention pertains to procurement of metallic device; in particular, parts for gas turbines of the flying constructions made from titanium alloys. To produce such metallic devices, the following range of procedures must be brought into action. Firstly, one or several non-metallic junction-predecessors should be made ready, each containing metallic composition element therein. These need to be chemically restored to procure a multitude of initial metallic particles, preferably those whose size varies between 0.0254 mm to approximately 13 mm, which do not have to be melted down. After having been fused at a later stage, they will solidify. The melted and solidified metal can be used either as a casting metal product or can be transferred into a partially finished product (billet) to be processed additionally until it is ultimately ready. The invention permits to substantially reduce the frequency of chemical faults in a metal product.

EFFECT: procurement of metal products by means of reconstruction of non-metal junction-predecessors and by fusion with a view to decrease the frequency of any chemical faults.

19 cl, 4 dwg

FIELD: nonferrous metallurgy.

SUBSTANCE: invention relates to manufacturing zirconium powder for making pyrotechnic articles, in particular explosive and inflammable mixtures. By-layers prepared powered mixture of potassium fluorocirconate and alkali metal chloride, preferably sodium chloride, at ratio 1:(0.15-0.6) and sodium metal in amount exceeding its stoichiometrically required amount by 10-20%. Preparation involves grinding of potassium fluorocirconate and alkali metal chloride to fineness below 50 μm as well as preliminary recrystallization of potassium fluorocirconate. Charge is heated to temperature 450-600°C, at which reduction reaction starts and during this reaction reaction mixture heats to 700-800°C and reduction of potassium fluorocirconate takes place. Reaction products are cooled to 400-650°C and freed of sodium through vacuum distillation at residual pressure 1.3-13.3 Pa for 0.5-2.0 h, after which they are discharged from reaction vessel and ground. Zirconium powder is washed with water to remove fluoride and chloride salts and then dried. Zirconium powder contains 95-98% of fine fractions, including fraction below 10 μm in amount 45-55%.

EFFECT: enhanced fineness of prepared zirconium powder end assured fire safety of the process.

8 cl, 3 ex

FIELD: treatment of powdered, especially metal containing initial material introduced together with treating gas such as reducing gas for creating fluidized bed in fluidized bed chamber, for example in fluidized-bed reactor.

SUBSTANCE: treating gas at least after partial conversion in fluidized bed is removed out of fluidized bed and then outside fluidized bed it is partially recovered, preferably oxidized due to performing chemical, namely exothermal reaction with gaseous and(or) liquid oxidizer. Heat energy of such reaction at least partially is fed to fluidized-bed chamber, especially to fluidized bed or it is taken out of it. Cyclone is arranged over fluidized bed in fluidized-bed chamber. Powdered initial material is heated or cooled in zone of cyclone, namely near inlet opening of cyclone due to using treating gas at least partially recovered over fluidized bed in fluidized-bed chamber, possibly heated or cooled, and(or) due to using system for recovering treating gas.

EFFECT: possibility for decreasing caking on distributing collector of fluidized-bed reactor, lowered slagging in zone of fluidized bed.

10 cl, 1 dwg

FIELD: powder metallurgy, possibly production of finely dispersed powder of molybdenum, its composites with tungsten, namely for producing hard alloy materials on base of molybdenum and tungsten.

SUBSTANCE: method provides production of molybdenum and its composites with tungsten at temperature no more than 900°C and also production of materials in the form of finely dispersed powders. Method comprises steps of reducing compounds of molybdenum and tungsten (MoO3 and WO3) by metallic magnesium in medium of melt chlorides such NaCl, KCl or carbonates such as Na2CO3, K2CO3 or their binary mixtures such as NaCl - KCl, Na2CO3 - K2CO3, NaCl - Na2CO3, KCl - K2CO3 at temperature 770 -890°C. According to results of fineness analysis produced powder of molybdenum represents homogenous material having 80% of particles with fraction size 2.2 - 3 micrometers. Composition material depending upon Mo content includes particles with fraction size 5 - 15 micrometers.

EFFECT: enhanced efficiency of method.

1 tbl, 3 ex

FIELD: non-ferrous metallurgy, possibly production of highly purified powders of tantalum and niobium with large specific surface by metal thermal reduction.

SUBSTANCE: method is realized at using as corrosion protection means layer of halide of alkali metal formed on inner surface of vessel before creating in reaction vessel atmosphere of inert gas. Charge contains valve metal compound and halide of alkali metal. It is loaded into reaction vessel and restricted by protection layer of halide of alkali metal having melting temperature higher than that of charge by 50 - 400°C. Before loading charge, valve metal compound and alkali metal halide may be mixed one with other. Mass of protection layer of alkali metal halide Ml and charge mass Mc are selected in such a way that that to satisfy relation Ml = k Mc where k - empiric coefficient equal to 0.05 - 0.5. Gas atmosphere of reaction vessel contains argon, helium or their mixture. Fluorotantalate and(or) oxyfluorotantalate or fluoroniobate and(or) oxyfluoroniobate of potassium is used as valve metal compound. Sodium, potassium or their mixture is used as alkali metal. Chloride and(or) fluoride is used as alkali metal halide. Valve metal compound and alkali metal halide may contain alloying additives of phosphorus, sulfur, nitrogen at content of each additive in range 0.005 - 0.1% and 0.005 - 0.2% of mass valve metal compound respectively. Invention lowers by 1.3 - 2 times contamination of powder with metallic impurities penetrating from vessel material. Value of specific surface of powder is increased by 1.2 - 1.8 times, its charge is increased by 10 - 30 %, leakage current are reduced by 1.2 - 1.5 times.

EFFECT: improved quality of valve metal powder, enhanced efficiency of process due to using heat separated at process of reducing valve metal for melting protection layer.

9 cl, 1 tbl, 4 ex

The invention relates to the metallurgy of tungsten, in particular the production of metallic tungsten from wolframalpha compounds, in particular SelidovUgol concentrate
The invention relates to powder metallurgy and can be used to obtain powder for capacitor production

FIELD: non-ferrous metallurgy, possibly production of highly purified powders of tantalum and niobium with large specific surface by metal thermal reduction.

SUBSTANCE: method is realized at using as corrosion protection means layer of halide of alkali metal formed on inner surface of vessel before creating in reaction vessel atmosphere of inert gas. Charge contains valve metal compound and halide of alkali metal. It is loaded into reaction vessel and restricted by protection layer of halide of alkali metal having melting temperature higher than that of charge by 50 - 400°C. Before loading charge, valve metal compound and alkali metal halide may be mixed one with other. Mass of protection layer of alkali metal halide Ml and charge mass Mc are selected in such a way that that to satisfy relation Ml = k Mc where k - empiric coefficient equal to 0.05 - 0.5. Gas atmosphere of reaction vessel contains argon, helium or their mixture. Fluorotantalate and(or) oxyfluorotantalate or fluoroniobate and(or) oxyfluoroniobate of potassium is used as valve metal compound. Sodium, potassium or their mixture is used as alkali metal. Chloride and(or) fluoride is used as alkali metal halide. Valve metal compound and alkali metal halide may contain alloying additives of phosphorus, sulfur, nitrogen at content of each additive in range 0.005 - 0.1% and 0.005 - 0.2% of mass valve metal compound respectively. Invention lowers by 1.3 - 2 times contamination of powder with metallic impurities penetrating from vessel material. Value of specific surface of powder is increased by 1.2 - 1.8 times, its charge is increased by 10 - 30 %, leakage current are reduced by 1.2 - 1.5 times.

EFFECT: improved quality of valve metal powder, enhanced efficiency of process due to using heat separated at process of reducing valve metal for melting protection layer.

9 cl, 1 tbl, 4 ex

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