Method for producing high-purity niobium ingots with normalized level of electrophysical properties

The invention relates to the field of special electrometallurgy and can be used to obtain ingot niobium of high purity with a regulated level of electrophysical properties, including specified interval of 200...500 ratio of specific elektrosoprotivlenie at T=293 K and T=9,2 K.

A known method of producing niobium ingots of high purity by six-electron-beam remelting draft niobium obtained aluminothermic recovery of niobium pentoxide, in the electron beam furnace, equipped with a steam-high-vacuum pumps when the pressure in the furnace chamber ~5·10^-4PA [1].

The disadvantage of this method is the low productivity, low value ρ₂₉₃/ρ_9,2that are in the range 100-350 and unregulated change from heat to heat, and one section of the ingot.

The disadvantages of this method are the need for and operation of very complex equipment associated with the creation of ultra-high vacuum, low productivity of the process because of the long period of preparation of electron-beam furnace for smelting, and the unregulated value ρ₂₉₃/ρ_9,2varying within very wide limits.

The closest technical solution selected in the quality of the ve prototype is a method of producing niobium ingots of high purity, including electron-beam remelting of consumable niobium billet (Zelikman A.N. Niobium and tantalum, Moscow, metallurgy, 1990, s[2]).

Our proposed method differs from the known fact that to obtain ingot niobium of high purity, including those specified in the range of 200-500 ratio of specific elektrosoprotivlenie at temperatures 293 K and 9.2 To as consumable procurement use preparation of niobium grade NB-1 and uniformly distributed along its length niobium received production by iodide refining, is determined from the ratio of specific elektrosoprotivlenie at temperatures 293 K and 9.2 To the terms set forth in the claims and in the description.

The technical problem solved by this invention is to produce ingots of niobium of high purity specified in the range 200...500 ratio of specific elektrosoprotivlenie at T=293 K and T=9,2 To providing increase productivity up to 13% and reducing the cost of ingot niobium of high purity up to 25% depending on the specified value ρ₂₉₃/ρ_9,2.

The solution of the problem reach that carry out electron beam remelting of consumable niobium billet, characterized in that to obtain ingot niobium with C the data in the range 200...500 ratio of specific elektrosoprotivlenie at temperatures 293 K and 9.2 K, as a consumable procurement use preparation of niobium grade NB-1 and uniformly distributed along its length niobium received production by iodide refining, while the mass ratio of niobium grade NB-1 and NB obtained production by iodide refining, is determined from the ratio of specific elektrosoprotivlenie at temperatures 293 K and 9.2 K, the expression:

m_n/m_u=(500-ρ₂₉₃/ρ_9,2)/(800+2×ρ₂₉₃/ρ_9,2),

where m_n- weight of niobium grade NB-1, g;

m_u- weight of niobium, received production by iodide refining, g;

ρ₂₉₃is the specific resistivity of niobium at T=293 K, Ohm·m²/m;

ρ_9,2is the specific resistivity of niobium at T=9,2, Om·m²/m

Conducted by the applicant experiments to obtain a niobium ingots of high purity with ratio ρ₂₉₃/ρ_9,2=200...500, the results of which are shown in table 1, show that the use ERF consumable billet consisting of niobium grade NB-1 and NB obtained production by iodide refining, in the ratio of m_n/m_u=0...0,25 allows you to get the metal with the specified value ρ₂₉₃/ρ_9,2in the interval from 200 to 500.

Thus, the use of consumable billet made from 100% niobium iodide refining, allows to obtain ingots with Á ₂₉₃/ρ_9,2=500, and the addition of niobium grade NB-1 in the amount of 0.14 and 0.25 by weight of niobium iodide refining allowed to obtain values ρ₂₉₃/p_9,2=300 and 200 respectively.

Examples of the proposed method.

Example 1.

To obtain ingot niobium of high purity with assigned values ρ₂₉₃/ρ_9,2=210±10 and 300±10, technology and technical-economic indicators which p is Evegeny in table 2, as a consumable billet used the ingot niobium grade NB-1 with a diameter of 0.1 m, a length of 0.7 m and a mass of 46250 g, the generatrix of which is uniformly distributed 74 niobium rod with a diameter of 0.02 m each received production by iodide refining, total weight 138750 g (m_n/m_u=0,25) - for a given value ρ₂₉₃/ρ_9,2=210±10 and consumable procurement of ingot niobium NB-1 with a diameter of 0.07 m, length 0.7 m, weight 25900 g and 87 niobium rods total weight of 185,000 g production by iodide obtained by refining (m_n/m_u=0,14) - for a given value ρ₂₉₃/ρ_9,2=300±10. Consumable billet was subjected to electron-beam remelting in two-gun fighter electron-beam furnace type EAF 07/500, equipped with high-vacuum steam-pumps nitrogen trap. Remelting was carried out in a mold with a diameter of 0.17 m through the intermediate tank sizes of 0.25×0.25 m, the intensity of the electron gun heating the melt in the mould, was 170 kW, and the power of the electron gun, running on fusion consumable billet heating of the melt in the hearth, was 150 kW. As a result of remelting speed of 11.1 g/sec when operating vacuum 7·10^-4PA 2 were obtained ingot niobium diameter 0,167 m weight 185000,

From the top, middle and bottom of the ingot is araseli cross-templates, of which produced samples for measuring ρ₂₉₃/ρ_9,2that put 90%cold deformation and subsequent vacuum annealing at T=1473 K for 4000 seconds, after which the measured value ρ₂₉₃/ρ_9,2the four-pin method at a constant current.

Obtained values of the parameter ρ₂₉₃/ρ_9,2was within 205-210 and 295-307, respectively, which fully meets the specified values.

Example 2.

To obtain ingot niobium of high purity with the specified value ρ₂₉₃/ρ_9,2=300±10 as consumable billet ERF used the niobium rods with a diameter of 0.02 m, the obtained production by iodide refining of deposition on the wire diameter 0,007 m, made of niobium grade NB-1. The total mass of spent preform of 40 bars, was 108000 g, from which the mass of the wire of niobium grade NB-1 m_n=134440 g, and the mass of niobium deposited on it in the process iodide refining m_u=94560 g ratio (m_n/m_u=0,14).

In the ERF spent this billet was obtained ingot niobium mass 107200 g, the upper and lower parts of which were sampled and measured ρ₂₉₃/ρ_9,2according to the above method.

The obtained values ρ₂₉₃/ρ_9,2was at the limit of the x 297-307, that is fully consistent with the specified values.

Remelting of consumable billet made from 100% niobium, received production by iodide refining, the same technology has led to the obtaining of ingot niobium with a value of ρ₂₉₃/ρ_9,2=495-501 (the prototype).

Comparison of technical and economic indicators of the receipt of the ingot niobium of high purity with the specified value ρ₂₉₃/ρ_9,2=300±10 the proposed method showed the possibility of increasing productivity by 14% and cost reduction of the metal by 11.5% due to the use of cheaper niobium grade NB-1 compared to the prototype.

The proposed method can be applied in industrial production of niobium of high purity with the specified value ρ₂₉₃/ρ_9,2in the range of 200-500 and manufacture of products used in physical-energy plants using low-temperature phenomena of superconductivity.

Sources of information

1. Production of niobium of high purity firm W/C/Heraeus GmbH,

“Journal of less-common metals, 1988, V.139, no. 1, p.p.1-14.

2. Zelikman A.N., Kites BG, Elyutin AV “Niobium and tantalum”, M “metallurgy”, 1990, s.

3. Refraction. “Iodide metals and iodides of metals”M “metallurgy”, 1968, s-123 /prototype/.

A method of producing niobium ingots of high pureness is, including electron-beam remelting of consumable niobium billet, characterized in that to obtain ingot niobium specified in the range 200...500 ratio of specific elektrosoprotivlenie at temperatures 293 K and 9.2 To as consumable procurement use preparation of niobium grade NB-1 and uniformly distributed along its length niobium obtained iodide refining, while the mass ratio of niobium grade NB-1 and NB obtained iodide refining, is determined from the ratio of specific elektrosoprotivlenie at temperatures 293 K and 9.2 K, the expression

m_n/m_u=(500-ρ₂₉₃/ρ_9,2)/(800+2×ρ₂₉₃/ρ_9,2),

where m_n- weight of niobium grade NB-1, g;

m_u- weight of niobium, the obtained iodide refining, g;

ρ₂₉₃is the specific resistivity of niobium at a temperature of 293 K, Ohm·m²/m;

ρ_9,2is the specific resistivity of niobium at a temperature of 9.2 K, Om·m²/m