A method of producing high purity vanadium

 

(57) Abstract:

The invention relates to the metallurgy of rare refractory metals, namely metallurgy of vanadium, and can be used to obtain high purity vanadium for the production of special alloys based on vanadium. The technical result of the invention is to improve the purity vanadium. A method of producing high purity vanadium includes aluminothermic recovery of vanadium-containing raw material when introduced into the initial charge of granular metallic calcium, melting recovered vanadium in electron beam furnaces followed by electrolytic refining of ingots obtained in the salt melt in two stages: the first stage electrolytic refining is carried out at current 0,03-0,1 kA for 4.0 to 4.5 hours when the number of cycles 2-20, on a second - by current of 0.8-1.0 kA for 4-8 hours when the number of cycles 250-300. Obtained after electrolytic refining powder vanadium mixed with a powder of a metal selected from the group of: calcium and/or rare earth metals, and/or aluminum, and compact in an effort to pressure of 2.0-2.1 tons/cm2with the preparation of the electrodes, which are additionally subjected to tre the species carried out at a speed of 5-6 kg/hour, the current 1.4 to 1.8 a and a residual pressure of 1·10-4mm RT.article; at a speed of 7-8 kg/h, the current of 1.6-2.0 a and a residual pressure of 4 to 10-5-5-10-5mm RT.article in the second stage and at a speed of 8-10 kg/h, the current 1.7 to 2.2 and a residual pressure of 2 to 10-5-5-10-6mm RT.article at the third stage. 4 C.p. f-crystals.

The invention relates to the metallurgy of rare refractory metals, namely metallurgy of vanadium, and can be used to obtain high purity vanadium for the production of special alloys based on vanadium.

Now greatly expanded the use of high-purity vanadium. In addition to the traditional use of vanadium as an alloying element for steel production and heat-resistant alloys, high-purity vanadium and alloys are widely used in the nuclear, aerospace and chemical engineering, using such properties of vanadium, as strength at high temperatures, low density, corrosion resistance, ductility at low temperatures and high technology.

For new applications the required purity vanadium ~4N.

Technical problem solved by the claimed invention, allcause aluminothermic recovery of vanadium from obtaining vanadium-aluminum alloy, containing excess oxygen and silicon. The silicon is removed by melting in an electron beam furnace in an oxidizing conditions for the formation of silicon oxide with subsequent removal in the gas phase with increasing temperature.

The excess oxygen is removed by heating the alloy in the presence of metallic calcium with the formation of calcium oxide (see U.S. patent No. 4099958, publ. 11.07.1978, NCI 75-84).

The disadvantage of this method is insufficient purification from admixtures. The resulting vanadium matches only brand VNM-0, with the content of vanadium 99,6-99,7.

A method of obtaining powder of vanadium, including the activation of the original compact of vanadium in two stages: first, at a temperature of 200 to 300°With the vacuum, the second at a temperature of 600-800°C in a hydrogen atmosphere, followed by hydrogenation of vanadium by cooling to a temperature of 50-200°C, the obtained vanadium hydride crushed and receive powder digitalout by heating to 650-800°With removal of hydrogen and holding at that temperature to a residual pressure of 0.05-0.50 mm RT.article (see RF patent №2196024, publ. 10.01.2003,, MPK 22 In 34/22).

The resulting vanadium corresponds brand VNM-0, with the content of vanadium 99,8.

The known method of vanadium in electron beam furnaces in two stages, conducted at a speed of 8-10 kg/h and the vacuum 1-10-4mm RT.art., and electrochemical refining of molten salts obtained ingots used as soluble anodes, with the receipt of vanadium on the cathode in the form of a crystalline precipitate. The method provides for obtaining vanadium purity of 99.85 wt.% (see RF patent №2164539, publ. 27.03.2001,, MPK 22 In 34/22). The method adopted for the prototype.

The technical result of the invention is to improve the purity vanadium.

The technical result is achieved in that in the method of producing high purity vanadium, including aluminothermic recovery of vanadium-containing raw materials, melting recovered vanadium in electron beam furnaces, electrolytic refining of ingots obtained in the salt melt, according to the invention the electrolytic refining of lead with obtaining vanadium powder, mix it with a powder of a metal selected from the group of: calcium and/or rare earth metals, and/or aluminum, compact mixture with the preparation of the electrodes, which are subjected to additional the three-stage melting in an electron beam furnace in a vacuum; in addition, aluminothermic restoration carried out at the are in two stages: the first stage is carried out at current 0,03-0,1 kA for 4-4,5 hours, number of cycles 2-20; the second stage with an electric current of 0.8-1.0 kA for 4-8 hours when the number of cycles 250-300, and with a uniform increase in current load between stages; the compacting of the mixture of powders with receiving electrodes is carried out at a pressure of 2.0 to 2.1 tons/cm2and an additional three-stage remelting electrodes in electron beam furnaces carried out at a speed of 5-6 kg/hour, amperage 1.4 to 1.8 a and a residual pressure of 1·10-4mm RT.article in the first stage; at a speed of 7-8 kg/hour, amperage of 1.6-2.0 a and a residual pressure of 4·10-5-5·10-5mm RT.article in the second stage and at a speed of 8-10 kg/hour, amperage 1.7 to 2.2 and a residual pressure of 2·10-5-5·10-6mm RT.article at the third stage.

The essence of the method lies in the fact that the alleged new combination and sequence of operations and their mode of implementation, which allows to obtain vanadium high purity of 99.99%.

For aluminothermic recovery using vanadium pentoxide purity of 99.5-99.7%, and the result vanadium aluminum content of 18%, and impurities, wt.%: Si To 0.08, Fe - 0,15, Mo - 0,007, Mn - 0,06; 0,13; N Is 0.01; Si 0,07; Ni - 0,006; Cr - 0,002.

The initial melting in an electron-beam furnaces can reduce the aluminium content, K0%. The content of impurities, wt.%: Al - 0,8; Si - 0,1; Fe - 0,05; Mo - 0,008; Mn - 0,01; 0,01; N Is 0.01; Si - 0,002; Ni - 0,005; Cr - 0,002.

The obtained ingots vanadium is subjected to electrolytic refining of molten salts in two stages. In the first stage is the main removal of metallic and gaseous impurities, and the second refining vanadium.

Purification of the electrolyte and the main refining process vanadium exercise properities, cycles, after the end of each cycle cathodic precipitates of vanadium powder is separated from the cathode and removed. The number of cycles in the first stage of electrolysis determines the purity of the electrolyte, and the second stage - the purity and structure of the cathode Deposit of vanadium.

The result electrolytic vanadium in the form of krupnogabaritnogo powder with a controlled content of impurities, wt.%: Al - 0,006; Si <1·10-5; Fe - 0,03; Mo <5·10-5; Mn - <1·10-4; C - 0,001; Ni - 0,004; Cr - 0,007; - 0,2; Na - 0,07; Cl - 0,3; 0,04; - 0,01; N Is 0.01.

The task of the subsequent operations is to reduce the concentrations of impurities. To do this, first made from electrolytic powder vanadium compact electrodes, and before compaction vanadium mixed with powder of metals, the Anadia 99.99% purity.

Substantiation of the parameters.

The first stage of electrolysis is directed primarily to the purification of the electrolyte, the process is useful to current 0,03-0,1 kA for 4-4,5 hours cyclically with the number of cycles 2-20. These parameters provide the reduction of Fe, Ni, gas impurities contained in the electrolyte, to the level 1·10-2-5·10-2wt.%.

Reducing the current below 0,03 kA leads to increased time of treatment cycle process and increasing energy consumption.

The increase in current more than 0.1 kA leads to contamination of the cathode sludge metal and gaseous impurities.

Conducting electrolysis in less than 4 hours when the number of cycles less than 2 leads to the insufficient amount of the formed cathode Deposit and performance.

More than 4.5 hours and the number of cycles more than 20 unproductive increase the energy consumption.

The II stage of electrolysis is aimed at obtaining high-purity vanadium and the second stage should also be cyclically.

The second stage of electrolysis at an amperage of less than 0.8 kA increases energy and reduces proizvoditeliami sediment and its shedding, decreases the degree of purification.

The process 4-8 hours and the reduction of its less than 4 hours leads to the insufficient quantity of generated cathodic sediment and decreased performance, and increased more than 8 hours leads to shedding of the cathode Deposit.

The number of cycles determines the maximum number of initial load and, consequently, the performance of the electrolysis process in General. Reducing the number of cycles reduces the volume of output of the anode metal, and the increase in the number of cycles results in substandard metal with a high content of impurities.

The introduction of metals at the stage of compacting electrodes it is necessary to increase the degree of refinement during subsequent melting of the electrodes in the electron beam furnace (ERF).

Holding triple remelting electrodes in ERF allows to obtain vanadium 99,99% only when using the vacuum and at the declared parameters of melting at all three stages.

The parameters of the first stage melting in ERF allow you to delete first gas impurities, the remains of the electrolyte and partially Fe, Ni, Cr and other metals.

The parameters of the second stage result in additional cleaning osmolal to obtain vanadium 99,99% with minimum losses to the gas phase.

Example.

For aluminothermic recovery of vanadium used the original vanadium pentoxide purity of 99.5-99.7%, and aluminum powder brand API. To the mixture was added granulated metallic calcium purity of 99.5-99.7 per cent to reduce the melting temperature of the slag and its viscosity, improve the separation of slag and metal, reducing the oxygen content in the shrinkage of the shell and increasing the recovery of vanadium on stage aluminothermic reduction (~2-3%). The process is conducted in an inert atmosphere.

Recovered vanadium contained impurities, wt.%: Al - 18; Si - 0,08; Fe - 0,15; Mo - 0,007; Mn - 0,06; 0,13; N Is 0.01; Si 0,07; Ni - 0,006; Cr - 0,002.

Recovered vanadium were subjected to primary melting in the ERF to remove metallic impurities and aluminum oxide. The melting was carried out at Ia=1,4-And 1,8; U=25 kV; V=5-6 kg/h; POST=1·10-4mm RT.art., where Ia is the anode current

U - voltage

V - the speed of melting.

This has resulted in ingots of purity vanadium 99,0% with a yield of 97%.

The impurity content in wt.% was: Al - 0,8; Si - 0,1; Fe - 0,05; Mo - 0,008; Mn - 0,01; 0,01; N is 0.01; si - 0,002; Ni - 0,005; Cr - 0,002.

The obtained ingots were subjected to electrolytic refining of molten salts is the Idov NaCl, KCl and Vl3in the following ratio, wt.%:

NaCl 36,0 of 36.5; Vl317,0-17, 5mm; KCl else.

The process is conducted at a temperature of 700°C in two stages. The first stage was carried out at lower current loads when the value of Ia=0,03-0,1 kA, time of 4.0-4.5 hours and the number of cycles 2-20.

The first stage of electrolysis (treatment cycles) is intended for so-called primary treatment of electrolyte from impurities, particularly iron and Nickel. Moreover, the electrolyte may be further contaminated with iron at the preparatory operations, such as downloading. During the first stage of the electrolysis cathode metal to analyze the content of iron and Nickel and the iron content of less than 0.1 to 0.05 wt.% treatment cycles completed and begin the second (main) phase of electrolytic refining, which is carried out also in cycles, but with a substantially greater load current when the value of Ia=0,8-1,0 kA, for 4-8 hours and the number of cycles 250-300. The increase in current load should be evenly without jumps. After completing the second stage electrolytic refining of vanadium obtained cathode metal, impurity composition of which was, wt.%: Al - 0,006; Si <1·10-5; F2">The content of other impurities less than 5·10-5wt.% each. The yield after the process of electrolytic refining amounted to 70%.

The obtained electrolytic vanadium is krupnogalechny powder with a high content of Al, Fe, Cr, Ni, K, Na and CL. These impurities are removed electron beam melting. For this purpose, electrodes are made by compacting the cathode of vanadium in an effort to 2.0 to 2.1 tons/cm2with premixing electrolytic vanadium powder with high purity powder of calcium or rare-earth metals, or aluminum, for example, in the amount of 0.9 wt.%, and as the binder used alcohol. The resulting electrodes are subjected to three-stage electron-beam remelting under vacuum with increasing speed, current load and vacuum at each subsequent stage to obtain vanadium 99.99% purity under the following process parameters electron-beam melting:

I stage - speed passage 5-6 kg/h, the current of 1.4-1.8 a and a residual pressure of 1·10-4mm RT.article.

Stage II - the speed of passage of 7-8 kg/h, the current of 1.6-2.0 a and the residual pressure (4-5)·10-5mm RT.article.

Stage III - the speed of passage of 8-10 kg/h, the current 1.7 to 2.2 and a residual pressure of 2·10-5-5·10-6">A new combination and sequence of operations and a new combination of techniques (introduction of the electrode metals) and modes of electron beam melting electrodes of vanadium allowed to obtain high-purity vanadium content in wt.% the most stubborn impurities oxygen level (1-2)·10-2with Fe, Ni, Si, Cu, Cl, To not more than 0.005 obtaining vanadium brand VNM - 0000 (99,99%).

The obtained high-purity vanadium has a high performance plastic. The hardness Brunel initiated the construction (HB) is 55-65, while vanadium brand VNM 0001 containing vanadium 99,9 has a hardness of HIN=75-80.

1. A method of producing high purity vanadium, including aluminothermic recovery of vanadium-containing raw materials, melting recovered vanadium in electron beam furnaces, electrolytic refining of ingots obtained in the salt melt, characterized in that the electrolytic refining of lead with obtaining vanadium powder, mix it with a powder of a metal selected from the group calcium, and/or rare earth metals, and/or aluminum, compact mixture with the preparation of the electrodes, which are subjected to additional the three-stage melting in an electron-beam is tlaut when introduced into the initial charge of granular metallic calcium.

3. The method according to p. 1 or 2, characterized in that the electrolytic refining is carried out in two stages: the first stage is carried out at current 0,03-0,1 kA for 4.0 to 4.5 hours when the number of cycles 2-20, a second phase with an electric current of 0.8-1.0 kA for 4-8 h at the number of cycles 250-300, and with a uniform increase in current load between stages.

4. The method according to any of paragraphs.1-3, characterized in that the compacting of the mixture of powders with receiving electrodes is carried out at a pressure of 2.0 to 2.1 tons/cm2.

5. The method according to any of paragraphs.1-4, characterized in that the additional three-stage remelting electrodes in electron beam furnaces carried out at a speed of 5-6 kg/h, amperage 1.4 to 1.8 a and a residual pressure of 1·10-4mm RT.article in the first stage; at a speed of 7-8 kg/h, amperage of 1.6-2.0 a and a residual pressure of 4·10-5-5·10-5mm RT.article in the second stage and at a speed of 8-10 kg/h, amperage 1.7 to 2.2 and a residual pressure of 2·10-5-5·10-6mm RT.article at the third stage.



 

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