Valve metal powder production method

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 ferrous metallurgy and can be used to obtain metallothermic recovery 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 what these metals are classified as valve metals. The main electrical parameters of the capacitors, which are valve metals are: capacitance, breakdown voltage and leakage current. Therefore, one of the important characteristics of the powder is the value of its specific surface, as at a specified voltage capacity of the anode of the capacitor is proportional to the specific surface of the powder. Another important characteristic is the chemical purity of the powder, which depends on the purity of the initial reagents and conditions for the restoration of a valve metal from the molten salt. 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. Currently, the source reagents used to obtain powders have high enough purity. The main history is the nickname of undesirable impurities in the powders are corrosion products in the interaction of the melt with the material of the reactor. Corrosion products contaminate the resulting metal is tantalum or niobium, and subsequently cause degradation of the dielectric anodic film, which leads to increased leakage current. Existing methods of prevention of corrosion of the material of the reactor in contact with the melt at high temperatures, based on the reduction of the time of interaction of the fused connection valve with metal walls of the reactor or the decrease in corrosion rate due to the use of supplements added to the charge for recovery. However, these methods are not effective.

A method of obtaining powder of a valve metal (see U.S. Pat. U.S. No. 4684399, IPC422 In 34/20, 1987), including the introduction into the reaction vessel with a protective argon atmosphere of a halide of one or more alkali metals, their melting and subsequent submission to the resulting melt is continuously or discretely connection of a valve metal and an alkali metal, thereby reducing the contact time of the melt connection of a valve metal material of the reactor. Reconnection of a valve metal of the alkali metal is carried out at a temperature of 600-950°and stirring the melt. The mass of the portions of the input components ranges from 10 to 33 wt.% with respect to the total mass loading. After completion of the reaction, the resulting reaction is Assu cooled to room temperature, crushed and washed the powder of a valve metal from the halides of the alkali metal. As the connection valve metal is used ftorotane potassium, ftorotane sodium or salt of niobium. The reaction vessel is made from an alloy based on Nickel. The obtained powder of a valve metal have a value of specific surface area of 0.4-1.5 m2/year Capacity anode made from these powders, amounted to 12000 c/g at sintering temperature of 1560°and 22740 c/g at a temperature sintering 1480°C.

The powders produced by this method have low quality due to contamination by metal impurities entering the melt due to corrosion of the material of the reactor. The corrosion is most intense during melting salt of a valve metal prior to the filing of the metal reductant in the active interaction of the resulting melt with the material of the reactor. In addition, the resulting powders are not sufficiently large value of specific surface area.

Also known is a method of obtaining powder of a valve metal (see U.S. Pat. U.S. No. 5234491, IPC5B 22 F 9/18, 1993), mainly tantalum, including the loading of the halide of an alkali metal and an active additive in the reaction vessel with lid, made of Nickel or an alloy based on Nickel or iron, blow Rea the Torah argon at room temperature, the melting of alkali metal halide in an argon atmosphere, heating the melt to a temperature of 800-900°With an introduction into the reactor continuously or discretely salts of tantalum and restoration of the valve metal of the alkali metal in the melt stirring. As the halide of the alkali metals are chlorides or fluorides of sodium or potassium, and as an active additive is an alkaline or alkaline earth metals. The amount of the additive is not less than 1, the Main requirement that must meet the active additive is its higher thermodynamic potential and chemical activity in comparison with the material of the reactor. The effect of the additive is advanced relative to the material of the reactor interaction with residual moisture and oxygen present in the atmosphere of the reactor. Along with halides of potassium and sodium in the reaction vessel can be entered 10-30 grams of salt K2SO4that performs the role of alloying elements. The obtained powder of a valve metal have a value of specific surface area of 0.59-1,92 m2/year

The disadvantage of this method is that the amount of impurities in the melt due to corrosion of the material of the reactor, is still significant. Supplements interacting with moisture and oxygen present is the reactor, form oxides that fall into the melt and, as centers of crystallization when recovering tantalum from its salts, can be an additional source of contamination of the obtained powder with oxygen. In addition, the obtained powders have insufficiently high specific surface area.

The technical result of the method according to the invention is to improve the quality of the powder of a valve metal by reducing contamination of its products corrosion of the material of the reactor while providing a large specific surface of the powder.

The technical result is achieved in that in the method of producing powder of a valve metal, including loading in the reaction vessel mixture in the form of connection of a valve metal and the halide of an alkali metal, creating in the vessel atmosphere of inert gas introduction means for protection against corrosion, overheating of components with the formation of the melt, the restoration of a valve metal in the melt by its interaction with the alkaline metal with stirring, cooling the resulting reaction mass, chopping and washing powder of a valve metal from the halides of the alkali metal, according to the invention as a means for protection against corrosion using a layer of alkali metal halide, which is to create in the reaction the vessel atmosphere of inert gas f is rerout on the inner surface of the vessel, and the charge is loaded into the reaction vessel in such a way that it is limited to a protective layer of alkali metal halide and alkali metal halide is selected with a melting point of at 50-400°C above the melting temperature of the mixture.

The technical result is also achieved by the fact that before it is loaded into the reaction vessel, the components of the mixture are mixed with each other.

The technical result is also achieved by the fact that the weight of the protective layer of the halide of the alkali metal and the mass of the mixture correspond to the relationship:

MSL=k·MW,

where MSL- weight of the protective layer of alkali metal halide,

MWis the mass of the charge,

k is an empirical coefficient, k=0,05-0,50.

On the technical achievement of the aims that the connection of the valve metal is used ftorotane potassium or oxytetracyclin potassium or a mixture thereof, ferroniobate or oxymoronic potassium or a mixture.

On the achievement of the technical result is also aimed that the connection of a valve metal contains alloying additive comprising one or more elements selected from the group consisting of phosphorus, sulfur, nitrogen, and each item is contained in an amount of from 0.005 to 0.1% by weight of the connection of a valve metal.

On the achievement of the technical result is also aimed that as the school is full of sodium metal is used, potassium or a mixture.

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

The achievement of the technical result also contributes to the fact that the alkali metal halide contains alloying additive comprising one or more elements selected from the group consisting of phosphorus, sulfur, nitrogen, and each item is contained in an amount of 0.005 to 0.2% by weight of the connection of a valve metal.

The achievement of the technical result is also that as the inert gas used argon and/or helium.

Use as a tool for corrosion protection layer of a halide of an alkali metal and shaping it to create in the reaction vessel atmosphere of inert gas on the inner surface of the vessel provides protection from the interaction of the connection of a valve metal material of the reactor in the process of formation of the melt and at the initial stage of recovery powder of a valve metal. This contributes to the quality of the powder of a valve metal by reducing contamination of its products corrosion of the material of the reactor. In addition, the formation on the inner surface of the reaction vessel of a layer of a halide of an alkali metal contributes to maintaining the high specific surface of the powder and to improve the structure of process performance at the expense of the heat released in the process of recovery of a valve metal, the melting boundary layer.

To download components of the mixture in the reaction vessel so that the charge is limited to the protective layer of the halide of an alkali metal, contributes to the fact that during the formation of the melt and at the initial stage of recovery powder of a valve metal melt is not in contact with the reactor walls due to the difference of the melting temperature of the charge and the halide of an alkali metal, forming a protective layer. The mixture may be loaded into the reaction vessel before or after forming the protective layer on the inner surface of the vessel, but to create in the reaction vessel atmosphere of inert gas.

The choice of a halide of an alkali metal, forming a protective layer with a melting point at 50-400°C above the melting temperature of the charge allows the melting of the charge at a temperature below the melting temperature of the halide of an alkali metal, forming a protective layer. If the difference between the melting temperature of less than 50°will be the partial melting of the protective layer and reducing its protective function. The difference of the melting temperature of more than 400°it is difficult to provide given thermophysical characteristics of the used reagents and mixtures thereof.

To create the most effective protective layer, it is desirable that the weight of the halide is Christmas, metal, forming a protective layer, and the mass of the charge answered value:

MSL=k·MW,

where MSL- weight of the protective layer of alkali metal halide,

MWis the mass of the charge,

k is an empirical coefficient, k=0,05-0,50.

The value of the empirical coefficient k depends on the reactor design, as well as from thermophysical characteristics of reagents used and is within the range from 0.05 to 0.50. The value of the coefficient k that is close to the lower limit of 0.05, conforms to a cylindrical reactor as the most optimal, with a maximum difference (400° (C) the melting temperature of the halide of an alkali metal, forming a protective layer, and the charge and the value of the coefficient k that is close to the upper limit, conforms to a cylindrical reactor with a minimum of (50° (C) temperature difference.

The use of fortuntate or oxytetracycline potassium or mixtures thereof and ferroniobata or exeptionality potassium or mixtures thereof as the connection of a valve metal according to the proposed method allows to obtain a powder of a valve metal with a large specific surface. Along with fortuntate, exiforientation, ferroniobium and oxyphenonium potassium as the connection of a valve metal may be used ftorotane or ACS is ftorotane sodium or their mixture, ferroniobate or oxymoronic sodium or their mixture, and pentachloride tantalum or niobium. However, the cost of obtaining fortuntate and oxytetracycline or ferroniobata and exeptionality sodium is higher compared to the cost of fortuntate, oxytetracycline, ferroniobata and exeptionality potassium, and pentachloride tantalum and niobium have a relatively low boiling point (respectively 242°, 250°and therefore, when the temperature of the recovery will have a high vapor pressure. In addition, they are hygroscopic.

The presence of the connection of a valve metal alloying agent includes one or more elements selected from the group consisting of phosphorus, sulfur, nitrogen, in the quantitative content of each element in the range of 0.005-0.1% of the mass connection of a valve metal, increases the surface of the powder and, consequently, improve the quality of the produced anode. The content of alloying elements in the connection of a valve metal in an amount of less than 0.005 wt.% no significant influence on the formation of powder particles, and therefore there is a significant reduction of the specific surface of the powder. The alloying additive in the amount of more than 0.1 wt.% causes increased content of the impurities in the powder and causes the degradation of the dielectric is Lenka, in terms of the increase of the leakage current. The alloying additive may be introduced into the connection of a valve metal in the process of its receipt.

The use of sodium, potassium or mixtures thereof as alkali metal allows after recovery to obtain a mixture of salts, are well soluble in water, which allows to achieve 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 and cesium, and 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 a valve metal. 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 that will lead to a significant increase in the cost of production of the powder.

Use as a component of a mixture of the halide of an alkali metal chloride and/or fluoride reduces the melting temperature and melt viscosity. Applying a layer of a halide of an alkali metal as a means of corrosion protection provides the ability to control the heat balance in the recovery process of a valve metal, Thu which contributes to obtaining a high quality powder with a developed surface. Along 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 they are more expensive reagents that will lead to a significant increase in the cost of production of the powder.

The presence of a halide of an alkali metal alloying agent includes one or more elements selected from the group consisting of phosphorus, sulfur, nitrogen, in the quantitative content of each element in the range of 0.005 to 0.2% by weight of the connection of a valve metal, increases the surface of the powder and, consequently, improve the quality of the produced anode. The content of alloying elements in the alkali metal halide in an amount of less than 0.005 wt.% no significant influence on the formation of powder particles, and therefore there is a significant reduction of the specific surface of the powder. The alloying additive in the amount of more than 0.2 wt.% causes increased content of the impurities in the powder and causes the degradation of the dielectric film, which is expressed in the increase of the leakage current. The alloying additive may be introduced into the alkali metal halide in the process of getting it or before it is loaded into the reaction vessel as a component of the charge or halide of an alkali metal, forming a protective whom Loy.

The use of argon and/or helium to create a gas atmosphere in the reaction vessel protects against oxidation of liquid alkali metal and protects the restored gate metal from contamination by oxygen and other gases contained in the air. In addition, argon and helium limit the interaction of the vapor connection of a valve metal with the walls of the reaction vessel and thereby reduce contamination of the powder of a valve metal metallic components present in the material of the vessel.

The drawing shows the dependence of the empirical coefficient k from the logarithm of the volume V (m3) reactor of cylindrical shape.

In General, the method of producing powder of a valve metal according to the invention is as follows. On the inner surface of the reaction vessel, mostly made in the form of a cylinder, form a protective layer of alkali metal halide. Next zone of the reactor, is restricted to that layer, load the mixture in the form of individual components or in the form of a homogeneous mixture of powdered connection of a valve metal K2MF7(where M Is TA or Nb) and the halide of the alkali metal MeR (where Me is Na, K; R is Cl, F). If necessary, the connection of a valve metal and/or alkali metal halide in the process of obtaining volatileread Supplement. It can be entered into the halide of the alkali metal before it is loaded into the reaction vessel. The alloying additive includes one or more elements selected from the group consisting of phosphorus, sulfur, and nitrogen. The amount of additive is controlled within the specified limits taking into account the fact that each element of the additive connection of a valve metal is contained in an amount of 0.005-0.1% of its mass, and each element of the additive halide of an alkali metal is contained in an amount of 0.005 to 0.2% by weight of the connection of a valve metal. The mixture may be loaded into the reaction vessel and prior to the formation of a protective layer on the inner surface of the vessel. When loading a layer of a halide of an alkali metal mass MSLand the charge of mass MWmaintain the ratio of MSL=k·MWwhere the empirical coefficient k=0,05-0,50. The specific value of the coefficient k is chosen with regard to the form and volume of the reactor, and the difference of melting temperatures (50-400° (C) the alkali metal halide and a mixture according to the dependence shown in the drawing.

After loading the reaction vessel is pressurized, vacuum up to a pressure of 1-3 PA, filled with inert gas (argon, helium or mixtures thereof) and heated above the melting temperature of the mixture, but below the melting temperature of the alkali metal halide used as the protective layer. the donkey partial or complete melting of the charge in the reaction vessel with continuous stirring served liquid alkali metal (sodium, potassium or a mixture thereof) in an amount of 2-10 wt.% in excess of the stoichiometric quantity needed for full recovery of a valve metal. Then stop heating, cool the reactor to room temperature, remove the reaction mass, grind it, and the obtained powder of a valve metal is rinsed with water from the halides of the alkali metal. Washed from salt powder is treated consistently in a solution of HCl and HF aqueous solution, then washed with distilled water and dried.

Specific surface area of the obtained powder was measured by the method of thermal desorption of argon. The content of impurities in the powder was determined by spectral analysis. Technological testing of powders is as follows. From the resulting powder is pressed anodes with a diameter of 2.95 mm and a density of 4.5 g/cm3. The anode is sintered in vacuum resistance furnace for 30 min at a residual pressure of not more than 5·10-5PA and a temperature of 1400°C. Forming the anode lead 1% solution of phosphoric acid at a temperature of 80°to achieve voltage 70 V At a constant current density of 60 mA/g, and then incubated for 3 h at this voltage. Capacity measurement is carried out in 38% sulfuric acid solution at a frequency of 50 Hz with AC current bridge. The leakage current is determined at the voltage average of 0.75 in the mask forming voltage.

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

Example 1. On the inner surface of the cylindrical reaction vessel made of Nickel brand H0 and having a height of 400 mm and a diameter of 260 mm, form a protective layer of alkali metal halide in the form of salts NaF brand HC in the amount of 1.05 kg Then the volume of the reaction vessel, a limited protective layer, load the mixture in the amount of 15 kg salt of a valve metal K2TaF7containing 0.005 wt.% phosphorus and 0.1 wt.% sulfur, and 6 kg of salt of the halide of an alkali metal NaCl brand HC ratio of the mass of the protective layer NaF and charge mass corresponds to the value of the empirical coefficient k=0,05. The melting temperature of the charge is 597°and salts NaF - 997°, which corresponds To a temperature difference of 400°C. After loading the reagent vessel is pressurized, vacuum up to a pressure of 2 PA, filled with argon, heated to 630°C and maintained at this temperature until the melting half of charge. Then for 1 h with continuous stirring on the surface of the melt serves liquid sodium in the number 4,53 kg, gradually increasing the melt temperature to 870°C. followed by cooling of the reactor. Upon reaching room temperature the reaction mass is extracted from ElCat and the tantalum powder is rinsed with water from the salts NaCl, NaF and potassium fluoride (KF), formed in the reduction reaction. Washed from salt powder is treated consistently in a solution of HCl and HF aqueous solution, then washed with distilled water and dried.

Main characteristics of the tantalum powder obtained in Example 1, and the powders obtained in Examples 2, 3 and Example 4 of the prototype shown in the Table.

Example 2. In the Central part of the cylindrical reaction vessel load the mixture in the form of a homogeneous mixture consisting of 7 kg salt of a valve metal K2TaF7brand HC and 5.3 kg of the salt of the halide of an alkali metal KCl brand HTC, which was previously entered alloying additive in the form of monohydrogenphosphate ammonium (NH4)2HPO4in an amount of 5 g, which corresponds to the content 0,026% nitrogen and 0,029% phosphorus by weight salt K2TaF7. Then on the inner surface of the cylindrical reaction vessel to form a protective layer of alkali metal halide in the form of salts KCl brand HC in the number 6,15 kg weight of the protective layer KCl and charge mass corresponds to the value of the empirical coefficient k=0.5. The melting temperature of the charge is 718°and salts KCl - 768°, which corresponds To a temperature difference of 50°C. After loading the reagent vessel is pressurized, vacuum up to a pressure of 1 PA, fill the men, heated to 730°C and maintained at this temperature until the melting of charge. Afterward, 0.9 h with continuous stirring on the surface of the melt serves liquid potassium in the amount of 3.6 kg, gradually increasing the melt temperature to 840°C. followed by cooling of the reactor. Upon reaching room temperature the reaction mass is extracted, crushed and powder of tantalum washed with water from the salts KCl and salt KF formed in the reduction reaction. Washed from salt powder is treated consistently in a solution of HCl and HF aqueous solution, then washed with distilled water and dried.

Example 3. On the inner surface of the cylindrical reaction vessel made of Monel (Ni - 73%, Cu - 23%, Fe - 3%, Mn - 1%) and having a height of 300 mm and a diameter of 160 mm, form a protective layer of alkali metal halide in the form of NaCl salt in the amount of 2.7 kg, containing 0.2 wt.% sulfur. Then the volume of the reaction vessel, a limited protective layer, load the mixture in the amount of 6 kg salt of a valve metal, consisting of 5.5 kg K2NbF7and 0.5 kg of K2NbOF5and 3 kg of salt of the halide of an alkali metal NaCl, which was previously entered alloying additive in the form of potassium sulfate K2SO4in the amount of 0.9 g, which corresponds to a sulfur content of 0.005% by weight of compounds of the veins is strong metal. The ratio of the mass of the protective layer NaCl and charge mass corresponds to the value of the empirical coefficient k=0,3. The melting temperature of the charge is 700°and salts of NaCl is 801°, which corresponds To a temperature difference 101°C. After loading the reagent vessel is pressurized, vacuum up to a pressure of 3 PA, fill with a mixture of argon and helium (volume ratio 1:1), heated to 720°C and maintained at this temperature until the melting of charge. Afterward, 0,6 h with continuous stirring on the surface of the melt serves a molten mixture of sodium and potassium in an amount of 2.5 kg (weight ratio 6:1), gradually increasing the melt temperature to 830°C. followed by cooling of the reactor. Upon reaching room temperature the reaction mass is extracted, crushed and powder of tantalum washed with water from the salts NaCl, and salts NaF and KF, resulting in the reduction reaction. Washed from salt powder is treated consistently in a solution of HCl and HF aqueous solution, then washed with distilled water and dried.

Example 4 (the prototype). In a cylindrical reaction vessel made of Nickel, and having a height of 400 mm and a diameter of 260 mm, is placed as a means of corrosion protection 0,045 kg of active substance in the form of sodium rod with a diameter of 38 mm and height 40 mm, Then download the alkali halides is of atalla KF and KCl in the amount of 2 kg and 12.5 kg and salt K 2SO4in an amount of 10 g, which plays the role of alloying elements. After loading the reagents of the reaction vessel at a temperature of 25°rinsed with argon at a rate of 100 cm3/h for 10 hours Then the temperature in the reaction vessel was raised to 225°C. After holding at 225°C for 4 h the temperature in the reactor was raised to 850°and maintain this temperature for 0.6 hours to melt loaded with salt. Then with continuous stirring on the surface of the melt serves liquid sodium with a speed of 2.7 kg/H. With the accumulation of sodium in an amount of 0.1 kg in the reactor serves salts valve metal K2TaF7in the amount of 0.9 kg - the first of 12 equal portions. The remaining portions of K2TaF7add in the reactor discretely after another dose of sodium, each of which is 0,27 kg When the total amount of sodium introduced into the reactor reaches of 3.33 kg, feed stop, and continuing the stirring, the temperature in the reactor was raised to 900°C. After cooling of the melt at this temperature for 2 hours, the reactor is cooled. Upon reaching room temperature the reaction mass is extracted, crushed and powder of tantalum washed with water from salts KF, KCl and the resultant reduction reaction of NaF. Washed from salt powder is treated in a mixture of acids, enabling the x HCl, HF and HNO3and dried.

Table
Example No.Means for corrosion protectionCharacteristic powder
The barrier metalThe content of the corrosion products of the reactor, ×10-4%Specific surface area, m2/gThe specific charge c/gLeakage current, ×10-4a/c
1NaFThe61,3514202,1
2KClThe40,98455602,0
3NaClNb51,95608002,5
4 prototypeNaThe80,82415003,0

From the above Examples and the Table shows that the proposed method can improve the quality of the powder of a valve metal. Compared with the prototype reduced 1.3-2.0 times the pollution of a powder metal impurities due to corrosion of the material of the reactor, the value of specific surface area of the powder increases 1.2-1.8 times, it is the charge increases by 10-30%, and the leakage currents are reduced by 1.2-1.5 times. In addition, the method can improve the performance of the process at the expense of the heat produced in the process of recovery of a valve metal, the melting of the protective layer.

1. A method of obtaining a powder of a valve metal, including loading in the reaction vessel mixture in the form of connection of a valve metal and the halide of an alkali metal, creating in the vessel atmosphere of inert gas introduction means for protection against corrosion, overheating of components with the formation of the melt, the restoration of a valve metal in the melt by its interaction with the alkaline metal with stirring, cooling the resulting reaction mass, chopping and washing powder of a valve metal from the halides of the alkali metal, characterized in that as a means to protect against corrosion using a layer of alkali metal halide, which is to create in the reaction vessel atmosphere of inert gas form 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 and alkali metal halide is selected with a melting point of at 50-400°C above the melting temperature of the mixture.

2. The method according to claim 1, characterized in that before loading reaction.you components of the mixture are mixed with each other.

3. The method according to claim 1 or 2, characterized in that the mass of the protective layer of the halide of the alkali metal and the mass of the charge answer value

MSL=k·MW,

where MSL- weight of the protective layer of alkali metal halide,

MWis the mass of the charge,

k is an empirical coefficient, k=0,05-0,50.

4. The method according to claim 3, characterized in that the connection of the valve metal is used tortontilt, or acceptancetest potassium, or a mixture and pornopat, or exittimeout potassium, or a mixture.

5. The method according to claim 4, characterized in that the connection of a valve metal contains alloying additive comprising one or more elements selected from the group consisting of phosphorus, sulfur, nitrogen, and each item is contained in an amount of from 0.005 to 0.1% by weight of the connection of a valve metal.

6. The method according to claim 3, characterized in that the alkali metal is used, the sodium, potassium or a mixture.

7. The method according to claim 6, characterized in that the alkali metal halide used its chloride and/or fluoride.

8. The method according to claim 7, characterized in that the alkali metal halide contains alloying additive comprising one or more elements selected from the group consisting of phosphorus, sulfur, nitrogen, and each item is contained in an amount of 0.005 to 0.2% by weight of the connection valve is of atalla.

9. The method according to claim 1, characterized in that as the inert gas used argon and/or helium.



 

Same patents:

FIELD: hydrometallurgy; ore concentrates processing.

SUBSTANCE: the invention is pertaining to the field of hydrometallurgy, in particular, to processing of the loparite concentrate. The method includes a decomposing of the loparite concentrate at the temperatures of 103-105°C and the concentration of hydrofluoric acid of 38-42 mass % with production of the pulp containing fluorides of titanium, rare earth elements (REE), niobium, tantalum and sodium. The pulp is filtered at the temperature of 90-95°C with extraction into the fluorotitanium solution of fluorides of niobium and tantalum and no less than 58 % of sodium in terms ofNa2O and separation of the sediment containing fluorides of rare earth elements (REE) and a residual sodium. The produced solution is cooled down to 18-24°C with separation of the second sediment of sodium fluorotitanate. After that they extract niobium and a tantalum from the solution by octanol-1 extraction at a ratio of the organic and water phases as 1.1 : 1. The sediment of REE fluorides is washed from fluorotitanate by sodium water in a single phase at the temperature of 90-95°C and at the solid :liquid ratio = 1:2-2.5. The cleansing solution is separated and evaporated with extraction of the additional sediment of sodium fluorotitanate. After extraction of niobium and tantalum the fluorotitanium solution is evaporated and filtered with separation of the first sediment of sodium fluorotitanate from the concentrated solution of fluorotitanium acid, which is directed to extraction of titanium. The gained first, second and additional sediments of sodium fluorotitanate are combined and subjected to conversion with production of sodium fluorosilicate and the conversional fluorotitanium acid added to fluorotitanium solution before its evaporation. The technical result of the invention is a decrease in 2.0-2.5 times of the volume of the cleansing solutions at provision of a high degree of extraction of compounds of titanium and other target products. The produced sodium fluorotitanate contains the decreased amount of the impurity ingredients of calcium and strontium.

EFFECT: the invention ensures a decrease in two-two and a half times of the volume of the used cleansing solutions at provision of a high degree of extraction of compounds of titanium and other target products and a decreased amount of impurities of calcium and strontium in the sodium fluorotitanate.

7 cl, 1 dwg, 1 tbl, 3 ex

FIELD: metallurgy of rare and dispersed metals, chemical technology.

SUBSTANCE: invention relates to a method for extraction separation of tantalum and niobium. Method involves extraction separation of tantalum from niobium with organic solvent. As an organic solvent method involves using a mixture of methyl isobutyl ketone taken in the amount 40-80 vol.% with aliphatic (C7-C9)-alcohol taken in the amount 20-60 vol.%. At the extraction process tantalum transfers into organic phase and niobium - into aqueous phase. Then organic and aqueous phases are separated. Invention provides enhancing the extraction degree of tantalum into organic phase and to enhance the separation degree of tantalum and niobium in extraction.

EFFECT: improved separating method.

5 tbl, 5 ex

FIELD: metallurgy; methods of preparation of charges for production of niobium-bearing material.

SUBSTANCE: the invention is dealt with production of niobium-bearing materials used for production of special steels. The technical result is an increased degree of transition of niobium into an alloy, decreased share of impurities in the alloy, decreased production costs. For this purpose the charge for production of a niobium-bearing material contains the raw material containing niobium pentaoxide, a nickel-bearing material, aluminum, calcium oxide, calcium fluoride and an exothermic oxidative additive. At that in the capacity of the exothermic oxidative additive it contains potassium chlorate with moisture of 2-12% at the following ratio in shares in respect to the total weight of the charge: niobium pentaoxide - 0.470-0.520, nickel - 0.190-0.270, aluminum - 0.180-0.200, calcium oxide - 0.030-0.040, calcium fluoride - 0.003-0.004, potassium chlorate with moisture of 2-12% - 0.043-0.049. At preparation of the charge after mixing of components it is exposed to compaction in the crucible up to the value of the plastic strength of 0.4-10.0 MPa.

EFFECT: the invention ensures an increased degree of niobium transition into an alloy, decreased share of impurities in the alloy, decreased production costs.

2 cl, 1 tbl, 3ex

FIELD: electrometallurgy, namely processes for producing high-purity niobium ingots used in power generation plants operating with use of low-temperature superconductivity effect.

SUBSTANCE: method comprises steps of electron-beam refining of consumable niobium blank; using blank of niobium of given kind containing niobium uniformly distributed along its length and produced by iodide refining as consumable blank in order to produce niobium ingots with predetermined (in range 200 - 500) relation of specific resistances at temperature values 193K and 9.2K; determining mass relation of niobium of given kind and niobium produced by iodide refining according to relation of specific resistances at temperature values 193 K and 9.2 K with use of expression mn/mu = (500 - ρ2939.2)/(800 + 2 x ρ2939.2) where mn - mass of niobium of given kind, g; mu - mass of niobium produced by iodide refining, g; ρ293 - specific resistance of niobium at temperature 193K, ohm x m2/m ; ρ9.2 - specific resistance of niobium at temperature 9.2K, ohm x m2/m.

EFFECT: enhanced efficiency of process, lowered cost price of high-purity niobium ingots.

2 tbl, 2 ex

FIELD: production of pure niobium.

SUBSTANCE: method includes reducing fusion of niobium pentoxide with aluminum and calcium to provide crude ingots followed by heat treatment and multiple electron beam refining. As an additional raw material in step of reducing fusion sublimates (preferably in non-oxidized form) from second and subsequent electron beam refining are used. Such sublimates are obtained by subsequent cooling of furnace smelting chamber under residual pressure of 10-2-10-4 mmHg for 1.0-3.0 h, letting-to-helium under 1-3 mmHg for 1.0-3.0 h, and letting-to-air for 20-40 min. Sublimates are added in amount of 4.5 % based to feeding niobium pentoxide. Claimed method affords the ability to increase niobium pentoxide consumption by 73 kg in respect to 1000 kg of pure niobium in crude ingots.

EFFECT: production of pure niobium with increased effectiveness without deterioration of refined niobium quality.

2 cl, 1 tbl

The invention relates to pyrometallurgy, in particular the production of niobium from its oxide, and can be used for the production of ferroniobium

The invention relates to the field of hydrometallurgical processing of tantalum raw materials and are aimed at achieving its complex use

The invention relates to ferrous metallurgy and can be used to obtain alloy powders of tantalum or niobium

The invention relates to metals, in particular tantalum, and products made from tantalum, as well as to methods of obtaining and processing of tantalum

The invention relates to metallurgy tantalum production for structural products and tantalum capacitors
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

The invention relates to ferrous metallurgy and can be used to obtain alloy powders of tantalum or niobium
The invention relates to metallurgy, in particular, to obtain granules and powders of rare and radioactive metals and their alloys

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

The invention relates to powder metallurgy and can be used to obtain high-purity powders of tantalum and niobium with a large specific surface for the production of capacitors
The invention relates to the field of powder metallurgy and concerns a method for obtaining powders of refractory compounds on the basis of a carbide or nitride of titanium compounds that can be used for the production of cutting tools, metal fittings, etc

The invention relates to the production of powders of refractory metals and can be used in enterprises: non-ferrous metallurgy in the production of high-quality hard alloys; chemical industry for preparation of catalysts; the electronics industry in the manufacture of bodies glow and so on

The invention relates to powder metallurgy, in particular to the manufacture of powders based on iron, and can be used in chemical industry and medicine

The invention relates to ferrous metallurgy, in particular to obtain a powder of alloys based on titanium metals, soluble in liquid magnesium, metallothermic recovery of titanium chloride (IV)

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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