Method for production of pure niobium
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 the field of metallurgy of rare refractory metals, in particular the production and purification of niobium, and pyrometallurgical processing it vysokomehanizirovannyh waste.
A known method of producing niobium, including the recovery of niobium pentoxide aluminum and subsequent vacuum refining electron-beam remelting (ELLAS) ingots draft niobium (Zelikman A.N. and other Niobium and tantalum), metallurgy, 1990, s-209). The disadvantages of this method are the low output, high aluminum content in draft niobium. Low yield due to incomplete recovery of niobium pentoxide and largely education operations ERF so-called action - vysokomehanizirovannyh waste resulting from evaporation and subsequent condensation at conducting heat. It seems appropriate to introduce technological turnover of these wastes to extract the metal.
Sublimates is a conglomerate of pieces of different sizes and properties: from fragile with low content of niobium to vysokomehanizirovannyh and goldcrests with a high content of metals.
In addition to metal and its oxides in the sublimates contains other compounds of niobium, as well as connections to other components of the recovery and impurity elements.
In connection with such establishments is m the composition of these wastes cannot be used directly for the production of crude niobium.
The action can be seen as artificially obtained niobium rich concentrate, which after proper processing, it is possible to obtain purified niobium.
Such treatment may be a method of decomposition of hydrofluoric acid (Zelikman A.N. and other Niobium and tantalum), metallurgy, 1990, p.51-53), which is the main processing of rich ore concentrates.
By analogy with the described in the specified way technology sublimates must be crushed, for which they previously have, for example, to gidrirovanii, and after grinding to degidrirovanii, then subjected to oxidative roasting and to open when the heat better in a mixture of hydrofluoric and sulfuric acid. And only thus obtained patikis niobium can be used to rebuild.
Possible direct dissolution of sublimates in mineral acids, for example, a mixture of HF and H2SO4but this long and also unsafe process with release of hydrogen.
As you can see, there are ways to recycle sublimates macoeconomic and insecure.
Known and chosen as a prototype method for producing the niobium restore his pentoxide aluminum and calcium, heat treatment and subsequent multiple ERF (RF patent 2137857, IPC From 22 In 34/24; 5/04; 9/22, priority 28.04.98). In this way significant holocaustului recovery resulting in cleaner rough metal, and in combination with subsequent heat treatment contributes to the appearance on the operation ERF cleaner metal and, ultimately, leads to reducing the number and improving the quality of action.
However, even this reduced number of sublimates (up to 120 kg per 1 ton of product) with a reduced content of impurities, and therefore with a high content of niobium (sublimates the first ERF received by the specified method contain up to 50% Nb, and the second 80-90%, and still further above), it is at least partially recycled to the extraction of niobium, and cost-effective and safe way.
The need for at least partial processing of the action, i.e. entry into the technological revolution, is explained by the following.
Sublimates the first remelting contain significant amounts (>50%) difficult to remove impurities and their separation and withdrawal is possible and justified, for example, using the above chemical (acid).
The necessity of withdrawal of sublimates the first ERF can be justified also by the fact that if the closed-loop system of production of crude metal, subsequent ERF, processing and inclusion in the process of sublimates will not be output impurities, they will accumulate and result in an obviously substandard about the products (ingots etc.). Sublimates the second and subsequent ERF advisable to enter into the technological turnover other less costly, for example, pyrometallurgical methods.
For the most efficient use of sublimates the second and subsequent ERF need to ensure their getting in minimally oxidized form, and optimally in the form of metal. On the existing technology of opening of the melting chamber of the furnace and cooling the obtained sublimates with the inlet air a large part of the metal is oxidized to a mono-, bi - and pentoxide. Pronounced metal (non-oxidized) fraction is formed in the amount of ~10%.
The objective of the invention is to provide a method of obtaining pure niobium using as an extension of raw materials to the restore operation sublimates ERF, which reduces the consumption of primary niobium pentoxide and ensures the achievement of the technical result consists in reducing the cost of production.
The technical result is achieved in that in the method of obtaining pure niobium from his pentoxide, including the recovery of aluminum and calcium to produce ingots draft niobium, heat treatment and subsequent multiple electron-beam remelting, the recovery is carried out in the presence mainly of oxygenated sublimates obtained after the second and p is the following ERF and added in quantities of up to 4.5% compared to niobium pentoxide.
The technical result is also achieved by the fact that mostly unoxidized sublimates get when creating the following conditions after conducting remelting: sequential cooling chamber electron beam furnace at a residual pressure of 10-2-10-4mm Hg during 1,0-3,0 hours, the helium inlet and keeping in an atmosphere of helium at a pressure of 1-3 mm Hg during 1,0-3,0 hours, the inlet air within 20-40 minutes.
With the addition of specially trained mainly of oxygenated sublimates after the second and subsequent refining of the reaction temperature recovery enough to melt the optimal number of sublimates, mainly consisting of metal and residual oxides. Impurities from the metal fraction sublimates at this otslaivayutsya, and oxides novostankuvata excess reagent (calcium and aluminium, available in the main charge.
Replacement part of the original raw material is niobium pentoxide by sublimates allows to reduce production costs by approximately 5-8%.
The proposed method was carried out as follows.
To increase the mass fraction of metal (non-oxidized) fraction sublimates used the following technology opening the oven EMO-250 after the second and subsequent ERF:
- cooling chamber melting furnace under high vacuum (residual pressure of 10- -10-4mm Hg) for 1,0-3,0 hours;
- overlap of helium in the chamber for melting and cooling in helium atmosphere (pressure of 1-3 mm Hg) for 1,0-3,0 hours;
final inflow of air into the melting chamber within 20-40 minutes.
If these parameters are not completely matured, the first, was at least partial oxidation of sublimates, and to different degrees, and to restore them required additional amount of reducing agents (calcium, aluminum), i.e. they were overrun, secondly, the interaction of air with the cooled niobium was accompanied by the formation of hydrogen that an early opening of the furnace could lead to microexplosion ("cotton"), that was created dangerous working conditions.
Longer compared with the specified mode cooling furnace economically impractical because it leads to increased duration of the process.
New technology is opening the furnace provides obtaining of oxygenated fraction sublimates in the amount of 80-90%. Thus obtained sublimates used for the restore operation.
When carrying out the bottoms compared the recovery results with the results of the existing standard technology (the prototype).
Before restoring large pieces of sublimates were crushed manually to the size of not more than 100 mm. Obtained sublimates mixed (Sredna the and) and the loading was carried out by 2 options: evenly in each channel metal reservoir or in the blend. The results of both versions were about the same.
The recovery results are presented in the table.
The quality of the metal was also assessed by the appearance of the bars. So the bars all heats except No. 1, had a good surface quality, and the melting ingots No. 1 part had the appearance of "hedgehog". Obviously, when loading such a large number (5,2%) sublimates heat of reaction recovery is not sufficient to fully melt the action.
Thus, the number loaded on regenerative heat sublimates the second and subsequent ERF amounted to 4.5%. A greater number of loadable sublimates deterioration of quality ingots.
The table shows that the number of pure niobium pentoxide required to produce 1 ton of pure niobium in the rough ingots and skull, when loading to restore sublimates in the amount of 3.7 to 4.5% by weight of loaded Nb5O5is in the range 1402-1456 kg (average value of 1430 kg)and without loading sublimates in the interval 1467-1537 kg (average value 1503 kg). Thus, when the loading on recovery of up to 4.5% of action savings niobium pentoxide will average ~73 kg per 1000 kg of pure niobium in the rough ingots and skull compared with the standard bottoms without loading speed. At the same time, the output of the niobium ingot and the crust remains almost t the m level.
According to the results of the analysis revealed that the content of impurities in the ingot was at the level of the standard heats and averaged 5.1 per cent.
Draft niobium obtained using sublimates, was aimed at refining by two or three times on ERF furnace EMO-250.
According to the results of two ERF average content of impurities in the ingot obtained from the draft of niobium with loading sublimates, was 0,141 wt.%, and bullion from the standard heats (prototype) - 0,142 wt.%, that was almost at the same level.
Metallographic studies of the bullion content of non-metallic inclusions present small single oxides of niobium, also confirm that the loading action does not affect the quality of the metal: the share of these inclusions in the ingot obtained by loading sublimates was 0.48%and bullion from the standard heats - up 0.51%.
Thus, the presented results demonstrate the solution of a technical problem - the creation of a method of obtaining pure niobium using as an additional raw material sublimates ERF, which reduces the consumption of niobium pentoxide for production and reduced its cost.
|The weight of the components of the mixture, kg||The share of action with respect to niobium pentoxide, %||The results of melting|
|patikis niobium||calcium||aluminum||sublimates||the total mass fraction of impurities, %||mass fraction of niobium, %||the output of niobium in the metal (bullion and the skull), %||spent the pure Nb5O51000 kg of pure niobium in bars and crust kg|
|Melting with the loading action:|
|2||1340||390||300||60||4,5||6,56||repossessed a 93.44||92,74||1452,83|
|4||1342,8||390||300||60||4,5||and 5.30||94,70||95.31 per||1425,38|
|the average value (No. 2-6) Nominal melting without loading sublimates||5,10||94,90||95,17||1430,5|
|9||1340||390||300||-||4.09 to||to 95.91||97,32||1467,87|
1. The method of obtaining pure niobium from his pentoxide, including the recovery of aluminum and calcium obtaining crude ingots, heat treatment and subsequent multiple electron-beam remelting, characterized in that the recovery of lead in the presence mainly of oxygenated sublimates obtained after the second and subsequent refining, and added in quantities of up to 4.5% compared to niobium pentoxide.
2. The method according to claim 1, characterized in that the predominantly non-oxidized sublimates receive sequential cooling chamber electron beam furnace at a residual pressure of 10-2-10-4mm Hg within 1-3 h, the overlap of helium and during curing in an atmosphere of helium at a pressure of 1-3 mm Hg within 1-3 h, the inlet air within 20-40 minutes