U.S. patent application number 12/306853 was filed with the patent office on 2009-10-15 for recycling of superalloys with the aid of an alkali metal salt bath.
This patent application is currently assigned to H.C. STARCK GMBH. Invention is credited to Michael Erb, Karl-Heinz Heine, Matthias Jahn, Uwe Kutzler, Juliane Meese-Marktscheffel, Armin Olbrich, Viktor Stoller, Rudiger Zertani.
Application Number | 20090255372 12/306853 |
Document ID | / |
Family ID | 38472960 |
Filed Date | 2009-10-15 |
United States Patent
Application |
20090255372 |
Kind Code |
A1 |
Olbrich; Armin ; et
al. |
October 15, 2009 |
RECYCLING OF SUPERALLOYS WITH THE AID OF AN ALKALI METAL SALT
BATH
Abstract
The invention relates to a process for recovering valuable
metals from a superalloy which has the steps of digesting the
superalloy in a salt melt. The salt melt contains 60-95% by weight
of NaOH and 5-40% by weight of Na.sub.2SO.sub.4.
Inventors: |
Olbrich; Armin; (Seesen,
DE) ; Meese-Marktscheffel; Juliane; (Goslar, DE)
; Jahn; Matthias; (Goslar, DE) ; Zertani;
Rudiger; (Goslar, DE) ; Stoller; Viktor; (Bad
Harzburg, DE) ; Erb; Michael; (Salzgitter, DE)
; Heine; Karl-Heinz; (Vienenburg, DE) ; Kutzler;
Uwe; (Bad Harzburg, DE) |
Correspondence
Address: |
CONNOLLY BOVE LODGE & HUTZ, LLP
P O BOX 2207
WILMINGTON
DE
19899
US
|
Assignee: |
H.C. STARCK GMBH
Goslar
DE
|
Family ID: |
38472960 |
Appl. No.: |
12/306853 |
Filed: |
June 29, 2007 |
PCT Filed: |
June 29, 2007 |
PCT NO: |
PCT/EP2007/056527 |
371 Date: |
February 12, 2009 |
Current U.S.
Class: |
75/10.67 ;
75/330; 75/392 |
Current CPC
Class: |
Y02P 10/224 20151101;
C22B 1/06 20130101; C01G 47/00 20130101; Y02P 10/214 20151101; Y02P
10/218 20151101; C22B 34/36 20130101; C01G 41/00 20130101; C22B
7/001 20130101; Y02P 10/23 20151101; Y02P 10/20 20151101; C22B
23/026 20130101; C22B 61/00 20130101 |
Class at
Publication: |
75/10.67 ;
75/330; 75/392 |
International
Class: |
C22B 1/00 20060101
C22B001/00; C22C 1/06 20060101 C22C001/06; C22B 61/00 20060101
C22B061/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 30, 2006 |
DE |
10 2006 030 731.3 |
Claims
1-21. (canceled)
22. A process for recovering valuable metals from a superalloy
which comprises digesting the superalloy in a salt melt containing
60-95% by weight of NaOH and 5-40% by weight of
Na.sub.2SO.sub.4.
23. The process according to claim 22, which further comprises
adding sodium carbonate in an amount not to exceed 10% by weight of
the salt melt.
24. The process according to claim 23, wherein the salt melt
contains 75-90% by weight of NaOH, 5-20% by weight of
Na.sub.2SO.sub.4 and 5-10% by weight of sodium carbonate.
25. The process according to claim 22, wherein the superalloy
contains one or more of the metals from the group consisting of Ni,
Co, Cr or Al as a main component and one or more of the elements
from the group consisting of Re, Mo, Ta, Nb, W, Hf or Pt as
secondary component.
26. The process according to claim 25, wherein the superalloy
contains 0.5 to 12% by weight of rhenium.
27. The process according to claim 22, wherein at least 1 kg of the
salt melt is used per 1 kg of superalloy.
28. The process according to claim 22, wherein the digesting is
carried out in a moving melt.
29. The process according to claim 23, wherein the digesting is
carried out in a rotary tubular kiln operated batchwise or
continuously.
30. The process according to claim 22, which further comprises
passing air and/or oxygen or a mixture thereof into the melt.
31. The process according to claim 22, which further comprises
adding oxidizing component to the melt, wherein the oxidizing
component is a nitrate, peroxodisulphate, peroxide of the alkali
metal and/or mixtures thereof.
32. The process according to claim 31, wherein 5 to 25% by weight
of the oxidizing component, based on the salt melt, are added to
the melt.
33. The process according to claim 30, wherein the mixture of air
and oxygen consisting of 25 to 95% by volume of air and 5 to 75% by
volume of oxygen is passed into the melt.
34. The process according to claim 32, wherein the digesting is
carried out at temperatures of 800 to 1200.degree. C.
35. The process according to claim 32, wherein the superalloy is
partly oxidized.
36. The process according to claim 22, wherein three fractions
consisting of: water-soluble alkali metal oxometallate of the
metals of the 6th and/or 7th subgroup and/or of the 3rd main group
of the Periodic Table of the Elements and/or mixtures thereof;
water-insolble components from the group consisting of the metals
Co, Ni, Fe, Mn or Cr and/or mixtures thereof, oxide and/or
water-insoluble alkali metal oxometallate of the metals of the 4th
or 5th subgroup of the Periodic Table of the Elements and/or
mixtures thereof are pre-formed in the melt.
37. A process for recovering valuable metals from a superalloy
comprising the following steps: a) converting of the melt digestion
product according to claim 36 into the solid phase by cooling to
room temperature, b) commination of the solidified melt digestion
product, c) reacting of the comminuted melt digestion product in
water at temperatures of less than 80.degree. C. and production of
an aqueous suspension containing a solution consisting of a mixture
of sodium compounds from the group consisting of NaOH,
Na.sub.2SO.sub.4, NaAl(OH).sub.4 and/or Na.sub.2CO.sub.3 and alkali
metallates of the elements of the 6th and/or 7th subgroups of the
Periodic Table of the Elements; a solid metallic phase consisting
of the group of metals Co, Ni, Fe, Mn and Cr; a solid phase
consisting of hydroxides and/or hydrated oxides of the metals of
the 3rd main group and of metals of the 4th and/or 5th subgroup of
the Periodic Table of the Elements, d) removing of the aqueous
fraction by filtration, e) separating of the water-insoluble
fraction by magnetic deposition of metallic components, and f)
removing the oxidic fraction.
38. The process according to claim 37, wherein the reaction of the
melt digestion product in water is carried out at temperatures of
less than 60.degree. C.
39. The process according to claim 37, wherein the reaction of the
melt digestion product in water is carried out at temperatures of
less than 40.degree. C.
40. A process for obtaining rhenium from a superalloy consisting of
the following steps: a) digesting the superalloy in a salt melt
consisting essentially of 60-95% by weight of NaOH and 5-40% by
weight of Na.sub.2SO.sub.4, b) cooling of the melt to room
temperature, c) commination of the melt digestion product, d)
reacting of the comminuted melt digestion product in water at
temperatures of less than 80.degree. C. and production of an
aqueous suspension containing a solution consisting of a mixture of
sodium compounds from the group consisting of NaOH,
Na.sub.2SO.sub.4, NaAl(OH).sub.4 and/or Na.sub.2CO.sub.3 and alkali
metallates of the elements of the 6th and/or 7th subgroup of the
Periodic Table of the Elements; a solid metallic phase consisting
of the group of metals Co, Ni, Fe, Mn and Cr; a solid phase
consisting of hydroxides and/or hydrated oxides of the metals of
the 3rd main group and of metals of the 4th and/or 5th subgroup of
the Periodic Table of the Elements, e) removing of the aqueous
fraction by filtration, and f) removing of the rhenium from the
aqueous fraction.
41. The process according to claim 40, which further comprises
adding sodium carbonate in an amount not to exceed 10% by weight of
the salt melt.
42. The process according to claim 22, wherein the superalloy is a
superalloy scrap.
Description
[0001] The present invention relates to a process for the digestion
of superalloys, in particular superalloy scrap, in a salt melt and
subsequent recovery of the valuable metals.
[0002] Superalloys are alloys which have a complex composition, are
stable at high temperatures and are based on nickel and cobalt,
with additions of other metals, such as, for example, aluminium,
chromium, molybdenum, tungsten, tantalum, niobium, manganese,
rhenium, platinum, titanium, zirconium and hafnium, and nonmetals,
such as boron and/or carbon. The superalloys are high-strength and
particularly hard-wearing alloys which are used in motor and engine
construction, in energy technology and in aviation and space
flight. The particular properties of these alloys are achieved in
particular by the addition of rare and noble metals, such as
rhenium, tantalum, niobium or even platinum. A good overview of the
composition, properties and fields of use of the superalloys is to
be found in Ullmann's Encyclopedia of Industrial Chemistry, Volume
A13, Fifth Edition, 1989, pages 55-65, and in Kirk-Othmer
Encyclopedia of Technology, Volume 12, Forth Edition, pages
417-458.
[0003] The superalloys differ from the customary high-melting
alloys, e.g. W--Re alloys or Mo--Re alloys, in their particular
resistance to oxidation or corrosion. Thus, owing to their
excellent oxidation stability, components comprising superalloys
are used in the production of blades in aircraft turbines. After
elapse of the duration of use, such parts are an important raw
material source for recovering rare metals, in particular rhenium,
tantalum, niobium, tungsten, molybdenum and platinum.
[0004] The recovery of the alloy metals of the superalloys is
commercially very interesting owing to the high proportion of
expensive metals. Thus, special superalloys contain the metals
rhenium in up to 12% by weight, tantalum in up to 12% by weight,
niobium in up to 5% by weight and tungsten and molybdenum in up to
12% by weight. Further metals which serve as base metals in the
superalloys are nickel and cobalt. For the last-mentioned metals,
too, the superalloys are a raw material source from which the
recovery of these metals is commercially expedient.
[0005] For the recovery of the metallic components from
superalloys, a large number of hydrometallurgical or
pyrometallurgical and electrochemical processes are known which,
owing to their complex embodiments and high energy demand, are not
processes which are not carried out on a large scale from
commercial points of view, especially owing to the constantly
increasing energy prices.
[0006] According to the prior art, for the recovery of the metallic
components from the superalloys, the latter are melted kept under
an inert gas atmosphere and then atomized to give a finely divided
powder. In this procedure, a disadvantage is that the superalloys
melt only at high temperatures between 1200 and 1500.degree. C. The
actual digestion of the superalloy takes place only in a second
step by treatment of the powder obtained with acids. Experience has
shown that several days are required for this purpose. According to
another process, clump-like superalloy scrap is first comminuted by
energy-intensive milling processes after prior embrittlement, for
example at low temperatures, and then digested by a wet-chemical
method at elevated temperatures in mineral acids of a certain
concentration and composition, Potter et al., Eff. Technol.
Recycling Metal 1971, page 35 et seq.
[0007] Furthermore, some processes which envisage the digestion of
the superalloy scrap via electrochemical processes are known.
[0008] According to U.S. Pat. No. 3,649,487, the high-melting
metals present in scraps of an Fe/Ni/Co/Cu base alloy, e.g.
tungsten, molybdenum and chromium, are first converted into
borides, carbides, nitrides, silicides or phosphides via a melting
process by addition of non-metallic compounds of group III, IV or
V, melted to give anodes and then subjected to an anodic oxidation.
Those metals such as Co, Ni and Cu initially go into solution and
are deposited from this at the cathode, while the high-melting
metals, remain behind in the anode sludge, for example as borides,
carbides, etc. It is disclosed here that the metals Ni, Co, Cu are
separated from the high-melting metals, such as W, Mo or chromium,
but there is no information at all about whether complete
separation of these metals takes place. The document furthermore
provides no information about the cost-efficiency of the
process.
[0009] WO 96/14440 describes a process for the electrochemical
digestion of superalloys by anodic oxidation of the alloy in an
electrolysis bath with an organic solvent component. The document
discloses that up to 10% of water can be added to the electrolyte
solution so that the process can still be carried out according to
the invention. Otherwise, passivation of the anode occurs through
formation of a gel or a firmly adhering oxide layer, which can lead
to termination of the electrolysis. The working-up and separation
of the valuable substances from the suspension forming as a result
of the electrolysis are initially effected by filtration. The
filtration residue separated off and containing a part of the alloy
metals is then worked up thermally by calcination and subsequently
by the customary hydrometallurgical processes.
[0010] DE 10155791C1 likewise discloses an electrochemical
digestion process for superalloys. In this process, the superalloys
are first cast into sheets and then electrolytically digested in an
oxygen-free inorganic acid. Here, the problem of anodic passivation
is counteracted by reversal of the polarity of the electrodes. The
two last-mentioned processes can be implemented economically only
under certain general conditions, in particular very high rhenium
contents in superalloys.
[0011] DE 19521333 C1 discloses a pyrometallurgical digestion of
tungsten-containing hard metal and heavy metal scraps. The
digestion takes place at temperatures between 800 and 1000.degree.
C. in a salt melt which consists of NaOH and Na.sub.2SO.sub.4. In
these processes, a sodium tungstate melt is produced, which is
dissolved in water after subsequent cooling.
[0012] As in the present invention, tungsten hard metal scrap is
virtually completely digested there in alkaline,
sulphate-containing melt under oxidizing conditions by formation of
sodium tungstate. This is not surprising since the metallate is
distinguished by high stability and dissolves in the NaOH melt
under the reaction conditions. Thus, a complete dissolution process
of the hard metal scrap is ensured.
[0013] It was an object of this invention to provide a process for
the digestion and recycling of superalloys, in particular
rhenium-containing superalloy scraps, and working-up for recovery
of the valuable materials present therein as a more economical
alternative to recycling by anodic oxidation or acid digestion.
[0014] The object was achieved by a process for the recovery of
valuable metals from superalloys, the superalloys being digested in
a salt melt consisting of 60-95% by weight of NaOH and 5-40% by
weight of Na.sub.2SO.sub.4 and the melt digestion product formed
thereby then being worked up hydrometallurgically with the aim of
simple separation of the individual valuable metals.
[0015] The digestion is preferably carried out in a salt melt
consisting of 65-85% by weight of NaOH and 15-35% by weight of
Na.sub.2SO.sub.4, particularly preferably of 70-80% by weight of
NaOH and 20-30% by weight of Na.sub.2SO.sub.4.
[0016] In the case of superalloys with the digestion of which the
present invention is concerned, more than over 50% of the metallic
constituents, e.g. nickel or cobalt, do not form metallates under
the reaction conditions of DE 19521333 C1, and it was surprising
that a corresponding digestion could take place at all.
Furthermore, it was surprising that virtually all the nickel and
cobalt was present in metallic form after digestion and hence
particularly advantageous working-up of the melt digestion product
where the use of magnetic separation was possible. At least, this
results in a substantial economic advantage over the
electrochemical digestion processes cited for superalloys.
Superalloys according to the present invention are alloys which
contain, as main components, 50 to 80% of nickel, 3 to 15% by
weight of at least one or more of the elements cobalt, chromium and
optionally aluminium, and 1 to 12% by weight of one or more of the
elements rhenium, tantalum, niobium, tungsten, molybdenum, hafnium
and platinum.
[0017] The process according to the invention is suitable in
particular for rhenium-containing superalloys which contain up to
12% by weight of rhenium. The digestion according to the invention
of superalloys is advantageously carried out in such a way that up
to 10% by weight, preferably up to 8% by weight and particularly
preferably up to 5% by weight of sodium carbonate
(Na.sub.2CO.sub.3), based on the weight of the salt melt, are added
to the salt melt.
[0018] Advantageous compositions of the salt melt are listed in
Table 1.
TABLE-US-00001 TABLE 1 % by weight of % by weight of % by weight of
NaOH Na.sub.2SO.sub.4 Na.sub.2CO.sub.3 85 5 10 80 10 10 70 25 5 80
15 5 75 20 5 72 20 8
[0019] The superalloys may be present both in lump form and in
pulverulent form (grindings or grinding dusts).
[0020] The superalloy digestion can be carried out both in directly
heated furnaces, e.g. in furnaces with gas or oil firing, and in
indirectly heated furnaces, continuously or batchwise. The furnaces
suitable for this purpose are, for example, rotary furnaces and
rotary tubular kilns.
[0021] The digestion of superalloys is preferably carried out in a
moving alkaline melt in a directly fired rotary tubular kiln
operated batchwise.
[0022] The digestion according to the invention is carried out in
such a way that at least 1 kg of salt melt, preferably at least 1.5
kg and particularly preferably at least 2 kg are used per 1 kg of
superalloy. In the case of certain superalloys which have rhenium
contents greater than 8%, up to 5 kg of salt melt are used per
kilogram of superalloy.
[0023] The digestion according to the invention of superalloys
takes place particularly advantageously with regard to the
space-time yield if air and/or oxygen, or a mixture thereof, is
passed into the salt melt. A mixture of air and oxygen consisting
of 25 to 95% by volume of air and 5 to 75% by volume of oxygen,
preferably of 35 to 80% by volume of air and 20 to 65% by volume of
oxygen, is preferably passed into the salt melt.
[0024] The digestion according to the invention of superalloys is
carried out at temperatures of 800 to 1200.degree. C.
[0025] Preferably, the digestion is carried out in the temperature
range of 850 to 1100.degree. C., particularly preferably at 900 to
1050.degree. C. Good digestion conditions are present if oxidizing
agents are additionally introduced into the melt. For example,
nitrates, peroxodisulphates, peroxides of the alkali metals and/or
mixtures thereof can serve as such. Potassium nitrate, sodium
nitrate, sodium peroxide, potassium peroxide, sodium
peroxodisulphate, potassium peroxodisulphate and/or mixtures
thereof are advantageously used as oxidizing agents. Particularly
good digestion rates are achieved if 5 to 25% by weight of the
oxidizing component, based on the weight of the melt, are added to
the melt.
[0026] Advantageous compositions of the salt melt are shown in
Table 2.
TABLE-US-00002 TABLE 2 % by weight % by weight of % by weight of %
by weight of of oxidizing NaOH Na.sub.2SO.sub.4 Na.sub.2CO.sub.3
agent 70 10 -- 20 (NaNO.sub.3) 77 5 -- 18 (K.sub.2S.sub.2O.sub.8)
80 5 5 10 (Na.sub.2O.sub.2) 60 20 8 6 (NaNO.sub.3) 6
(Na.sub.2S.sub.2O.sub.8) 85 10 -- 5 (Na.sub.2O.sub.2)
[0027] The melt digestion is particularly advantageously carried
out in such a way that a partial oxidation of the superalloy takes
place or, after virtually complete oxidation, reducing conditions
are established for a certain time. In the digestion process
according to the invention, three fractions are pre-formed in the
melt itself, consisting of: [0028] water-soluble alkali metal
oxometallates of the metals of the 6th and/or 7th subgroup and/or
of the 3rd main group of the Periodic Table of the Elements and/or
mixtures thereof; [0029] water-insoluble components from the group
consisting of the metals Co, Ni, Fe, Mn or Cr and/or mixtures
thereof, [0030] oxides and/or water-insoluble alkali metal
oxometallates of the metals of the 4th or 5th subgroup of the
Periodic Table of the Elements and/or mixtures thereof.
[0031] These three fractions are then worked up
hydrometallurgically. The present invention therefore relates to a
process for working up the superalloy melt digestion product,
comprising the following steps:
a) conversion of the melt digestion product into the solid phase by
cooling to room temperature, b) commination of the solidified melt
digestion product, c) reaction of the comminuted melt digestion
product in water at temperatures of less than 80.degree. C. and
production of an aqueous suspension containing [0032] a solution
consisting of a mixture of sodium compounds from the group
consisting of NaOH, Na.sub.2SO4, NaAl(OH).sub.4 and/or
Na.sub.2CO.sub.3 and alkali metallates of the elements of the 6th
and/or 7th subgroups of the Periodic Table of the Elements; [0033]
a solid metallic phase consisting of the group of metals Co, Ni,
Fe, Mn and Cr; [0034] a solid phase consisting of hydroxides and/or
hydrated oxides of the metals of the 3rd main group and of metals
of the 4th and/or 5th subgroup of the Periodic Table of the
Elements, d) removal of the aqueous fraction by filtration, e)
separation of the water-insoluble fraction by magnetic deposition
of metallic components, f) removal of the oxidic fraction.
[0035] The process according to the invention is shown
schematically in the attached FIG. 1. According to FIG. 1, the
superalloy melt digestion product (2) is crushed after cooling to
room temperature, then comminuted in a mill and then leached in
water. Preferably, the leaching is carried out at temperatures of
less than 60.degree. C. and particularly preferably at less than
40.degree. C. The particular feature of the melt digestion
comprises the three fractions which are formed therein beforehand
and are present during the water leaching as fractions which can be
easily separated: [0036] the filtrate (4) which substantially
contains the elements molybdenum, tungsten and rhenium in the form
of their alkali metallates, [0037] the water-insoluble residue (3)
which consists of a magnetic fraction which contains practically
the total nickel and cobalt fractions of the alloy and about 1/3 of
the chromium used, in metallic form, while all other elements are
present only as secondary constituents or in the trace range, and
[0038] a nonmagnetic fraction (5) which contains the elements
aluminium, chromium, titanium, zirconium, hafnium, niobium and
tantalum in the form of their oxides (e.g. Al2O3, Cr.sub.2O3, TiO2,
ZrO2, HfO2, Ta2O5, Nb2O5), or hydroxides (e.g. Al(OH)3, Cr(OH)3,
Ti(OH)4, Zr(OH)4, Hf(OH)4, Ta(OH)5, Nb(OH).sub.5 or nitrides (e.g.
AlN, CrN, TiN, HfN, NbN and TaN) or carbides (e.g. AlC, Cr2C3, TiC,
ZrC, HfC, NbC and TaC).
[0039] The further working-up of these fractions can be effected by
the known methods. Thus, the rhenium can be separated off after the
filtration from the filtrate (4) over strongly basic ion
exchangers, as described in DE 10155791. The rhenium-free solution
containing substantially sodium molybdate and sodium tungstate can
be added to the process for obtaining molybdenum and tungsten.
[0040] The nonmagnetic residue, which contains up to 15% of
tantalum, can be used as raw material in tantalum-metallurgy.
[0041] The magnetic residue is advantageously used for the
production of cobalt and nickel.
[0042] The process according to the invention is suitable in
particular for recovering rhenium from superalloys. The present
invention furthermore relates to a process for obtaining rhenium
from superalloys, comprising the following steps:
a) digestion of superalloys in a salt melt consisting of 60-95% by
weight of NaOH and 5-40% by weight of Na.sub.2SO.sub.4, b) cooling
of the melt to room temperature, c) commination of the melt
digestion product, d) reaction of the comminuted melt digestion
product in water at temperatures of less than 80.degree. C. and
production of an aqueous suspension containing [0043] a solution
consisting of a mixture of sodium compounds from the group
consisting of NaOH, Na.sub.2SO.sub.4, NaAl(OH)4 and/or
Na.sub.2CO.sub.3 and alkali metallates of the elements of the 6th
and/or 7th subgroup of the Periodic Table of the Elements; [0044] a
solid metallic phase consisting of the group of metals Co, Ni, Fe,
Mn and Cr; [0045] a solid phase consisting of hydroxides and/or
hydrated oxides of the metals of the 3rd main group and of metals
of the 4th and/or 5th subgroup of the Periodic Table of the
Elements, e) removal of the aqueous fraction by filtration, f)
removal of the rhenium from the aqueous fraction according to DE
10155791.
[0046] The process according to the invention for obtaining rhenium
from superalloys is advantageously carried out in a manner such
that up to 10% by weight, preferably up to 8% by weight and
particularly preferably up to 5% by weight of sodium carbonate
(Na.sub.2CO.sub.3), based on the weight of the salt melt, are added
to the salt melt. The removal of the rhenium from the aqueous
suspension by means of strongly basic ion exchange resins is
preferred.
[0047] An advantage of the process according to the invention is
that the superalloy digestion in an NaOH--Na.sub.2SO.sub.4 melt is
exothermic. By passing in air or an air/oxygen mixture, the process
is readily controllable. A further advantage is that the valuable
substances can be virtually completely recovered.
[0048] The invention is explained in more detail with reference to
the following example.
EXAMPLE
[0049] 1.97 t of superalloy grinding dust (1) were heated together
with 2.50 t of NaOH and 0.45 t of Na.sub.2SO.sub.4 to 1110.degree.
C. in the course of 4 hours in a rotary furnace directly fired with
natural gas and left at this temperature for a further hour. The
composition of the superalloy grinding dust is shown in Table
1.
[0050] Thereafter, the resulting viscous superalloy melt digestion
product was completely poured out of the furnace. The cooled melt
was first coarsely crushed and then melted to <2 mm. 5.26 t of
pulverulent melt material (2) were obtained, which material was
stirred into 7.5 m.sup.3 of water for leaching. After the end of
the addition, stirring was continued for a further 2 hours,
followed by filtration over a filter press and rinsing with 0.5
m.sup.3 of water. 2.10 t of filter residue (3) and 9.3 m.sup.3 of
filtrate (4) were obtained. The filter cake was suspended again in
water, and the metallic, magnetic fractions were separated from the
oxidic and hydroxidic fractions by circulating the suspension
through a magnetic separator by means of a pump. The substantially
metal-free suspension was then separated again by means of a filter
press, and the filtrates were initially introduced for the next
leaching run. 1.46 t of metal sludge (5) and 0.56 t of hydroxide
sludge (6) were obtained. The hydroxide sludge (6) was sent to a
tantalum facility for recovering the tantalum, and the metal sludge
(5) was sent to a nickel facility for further working-up. The
rhenium-containing filtrate (3) was passed over ion exchange
columns with strongly basic ion exchangers for recovering the
rhenium. The further enrichment and purification of the rhenium
were effected by standard methods according to the prior art. The
rhenium-free outflow of the ion exchange columns was used in a
tungsten facility as an initially taken material for the leaching
of WO.sub.3. The rhenium yield was 94%.
[0051] The composition of the superalloy grinding dust and of the
most important intermediates is shown in Table 3.
TABLE-US-00003 TABLE 3 % kg % kg % kg g/L kg % kg % kg Al 9.28 183
4.47 235 1.46 30.5 21.9 204 0.12 1.7 5.05 28.4 Co 7.09 140 2.59 136
6.73 141 0.0 0.0 9.46 138 0.37 2.1 Cr 7.17 141 2.62 138 6.69 140
0.0 0.0 3.16 46.2 16.4 92.7 Hf 0.22 4.4 0.08 4.3 0.21 4.3 0.0 0.0
0.09 1.4 0.52 2.9 Mo 1.05 20.6 0.39 20.4 0.01 0.1 2.21 20.5 0.01
0.1 0.0 0.0 Ni 51.3 1001 19.0 999 47.9 1000 0.0 0.0 68.8 1006 3.14
17.7 Re 1.53 30.1 0.58 30.5 0.09 1.9 3.12 29.0 0.13 1.8 0.01 0.0 Ta
4.20 82.8 1.55 81.3 3.93 82.0 0.0 0.0 1.94 28.4 9.55 53.8 Ti 1.53
30.2 0.58 30.5 1.47 30.6 0.0 0.0 0.68 10.0 3.59 20.2 W 4.38 86.2
1.64 86.1 0.04 0.9 9.16 85.3 0.06 0.9 0.0 0.0 Zr 2.33 45.9 0.87
45.5 2.15 45 0.0 0.0 0.97 14.3 5.5 31.0 Non-metallic constituents
9.92 Total of metals 90.08 1775 1807 1476 339 1249 249
* * * * *