U.S. patent application number 10/798143 was filed with the patent office on 2004-09-16 for process for recovering metals, in particular precious metals, from electronic scrap.
Invention is credited to Cossali, Silvano, Maccagni, Massimo, Olper, Marco.
Application Number | 20040179985 10/798143 |
Document ID | / |
Family ID | 32750504 |
Filed Date | 2004-09-16 |
United States Patent
Application |
20040179985 |
Kind Code |
A1 |
Olper, Marco ; et
al. |
September 16, 2004 |
Process for recovering metals, in particular precious metals, from
electronic scrap
Abstract
The present invention relates to a process for recovering
metals, in particular precious metals, from electronic scrap,
comprising a leaching phase in which the electronic scrap is
treated with a leaching solution based on cupric chloride and an
alkaline chloride to dissolve the metals exposed to said solution,
with the exception of gold, and a subsequent recovery phase of gold
in solid form.
Inventors: |
Olper, Marco; (Monza,
IT) ; Maccagni, Massimo; (Sesto San Giovanai, IT)
; Cossali, Silvano; (Ponite Nossa (BG), IT) |
Correspondence
Address: |
James V. Costigan, Esq.
Hedman & Costigan, P.C.
Suite 2003
1185 Avenue of the Americas
New York
NY
10036-2646
US
|
Family ID: |
32750504 |
Appl. No.: |
10/798143 |
Filed: |
March 11, 2004 |
Current U.S.
Class: |
423/23 |
Current CPC
Class: |
C22B 7/007 20130101;
C22B 15/0069 20130101; Y02P 10/236 20151101; C22B 15/0089 20130101;
C22B 3/10 20130101; C22B 11/046 20130101; Y02P 10/214 20151101;
Y02P 10/234 20151101; Y02P 10/20 20151101 |
Class at
Publication: |
423/023 |
International
Class: |
C22B 015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 12, 2003 |
IT |
MI2003A 000468 |
Claims
1. A process for the recovery of metals, in particular precious
metals, from electronic scrap, characterized in that it comprises:
a leaching phase in which said electronic scrap is put in contact
with a leaching solution comprising cupric chloride and one or more
alkaline halides suitable for complexing the metallic species in
solution, to obtain the dissolution of the metals exposed to said
solution, with the exception of gold, a recovery phase of the gold
in solid form.
2. The process according to claim 1, characterized in that said
alkaline halides of the leaching solution are alkaline chlorides
selected from the group comprising sodium chloride, potassium
chloride, and mixtures thereof.
3. The process according to claim 1, characterized in that said
leaching phase is effected at a temperature ranging from 50 to
105.degree. C.
4. The process according to claim 3, characterized in that said
leaching phase is effected at a temperature ranging from 70 to
90.degree. C. for a time of 1 h -3 h.
5. The process according to claim 1, characterized in that said
leaching solution has a pH within the range of 0 to 3.
6. The process according to claim 1, characterized in that said
leaching solution has a copper content ranging from 20 to 50
g/l.
7. The process according to claim 1, characterized in that before
the recovery phase of the gold, a sieving phase is effected, in
which the leaching solution with the gold residues is separated
from the solid fractions.
8. The process according to claim 1, characterized in that said
gold recovery phase is effected by means of filtration.
9. The process according to claim 1, characterized in that it
comprises a further recovery phase of the silver from the leaching
solution.
10. The process according to claim 1, characterized in that it
comprises a further recovery phase of the copper from the leaching
solution.
11. The process according to claim 10, characterized in that the
leaching solution, by air bubbling, produces a precipitate based on
iron hydroxide and tin oxide, contemporaneously re-oxidizing the
cuprous chloride to cupric chloride.
12. The process according to claim 11, characterized in that the
solution is re-circulated to the leaching phase after recovering
said precipitate by filtration.
13. The process according to claim 1, characterized in that the
solid fractions, recovered from the sieving phase are subjected to
flotation to separate the cards and plastic material, magnetic
separation to recover the fraction rich in iron of the components
of the electronic circuits, separation with parasite currents to
separate the fraction rich in aluminum.
14. The process according to claim 13, characterized in that the
non-separated electronic components comprising the chips are ground
and re-circulated to the leaching phase for the recovery of the
remaining metal fractions.
Description
[0001] The present invention relates to a process for recovering
metals, in particular precious metals, from electronic scrap.
[0002] In particular, the present invention relates to a suitable
process for the recovery of precious metals such as Gold and
Silver, and other metals such as Copper, Aluminum, Tin, Zinc,
Nickel and Lead from electronic scrap, by effecting a separation of
the components and gold in solid form.
[0003] The technical field of application of the present invention
is the recycling of electronic scrap, in particular the recovery of
the metals contained therein.
[0004] In the last few years, this field has become increasingly
more important, due to the increase in volumes to be treated and
the development of technologies which allow the recovery of both
precious metals, such as, for example, gold, silver, and also of
non-noble metals such as copper, aluminum, iron, nickel, lead, tin
and zinc.
[0005] In current recovery techniques, the electronic scrap is
ground until it reaches a size of a few millimeters and fractions
rich in metals, among which mainly copper, are subsequently
mechanically and magnetically separated.
[0006] The metallic fractions are mostly integrated in the
productive cycle of copper, before the smelting of the anodes used
subsequently for the electrolytic refining of this metal. Precious
metals, among which mainly gold and silver, are then obtained from
the anodic sludge, characteristic of this type of refining process,
using well known processes.
[0007] A typical example of a refining process is provided by
Ronnskr Smelter of Boliden.
[0008] In this context, the electronic scrap is fed into the oven
Kaldo and the metal thus produced is added to the converter
together with the copper coming from the smelter, and then enters
the classical die for the production of copper. From the converter,
it then passes to the anode oven where copper anodes are produced,
which feed the electrolytic refining cell. Electrolytic copper
cathodes are produced in this unit, whereas the precious metals are
subsequently extracted from the anodic sludge produced (T. Lehner,
J. Wiklund, "The New Ronnskr Smelter"; Proceeding of EMC 2001,
Volume 1, Sep. 18-21, 2001; Friedrichschafen, Germany; Pages
49-59).
[0009] A part of the precious metals is also dispersed in the
polymer-based fractions, as well as in the metallic fractions, and
is therefore lost.
[0010] It should also be considered that, in thermal processes used
for the production of copper anodes, the possible presence in the
metallic fractions of polymeric material of the fireproof type,
thus containing reasonable quantities of halogen elements, leads to
the formation of dioxins (N. Menad, B. Bjorkman, S. Zhang and E.
Forsberg, "Thermodynamic Conditions for the Formation of Dioxin
during the Recycling of Non Ferrous Metals from Electric and
Electronic Scrap"; Proceedings of EPD Congress 1998 Ed. B. Mishra;
The Minerals and Materials Society; Feb. 16-19, 1998; San Antonio,
Tex., U.S.A.; pages 657-673).
[0011] At present, with the recovery methods traditionally used, it
is therefore indispensable to effect the grinding of electronic
scrap in order to reduce it to extremely small sizes.
[0012] This operation has the disadvantage of being extremely
costly and not very selective and necessitates separation systems
downstream which at times become very difficult to handle.
[0013] The final result envisages the formation of metal-based and
polymer-based fractions.
[0014] A serious drawback consists in the fact that in the
metal-based fractions there can be polymeric parts, in some cases
fireproof, which, in the case of a thermal process, as occurs in
the production of copper anodes, can lead to the production of
dioxins.
[0015] Grinding operations, on the other hand, are effected as
current recovery systems do not allow an effective separation of
the components.
[0016] Furthermore, the recovery of precious metals in the above
systems is only partial as a part is lost during the separation of
the metallic and polymeric fractions.
[0017] One of the objectives of the present invention is to effect
a process for recovering metals, in particular precious metals,
from electronic scrap which envisages a recovery selectivity of
precious metals such as gold and silver.
[0018] Another objective of the present invention consists in
effecting a process for recovering metals from electronic scrap
which allows a simple but effective separation of the
components.
[0019] Yet another objective is to provide a process for recovering
metals, in particular precious metals, from electronic scrap,
reducing the grinding operations and emission into the atmosphere
of polluting or toxic substances to the minimum.
[0020] A further objective of the invention is to effect a process
for recovering metals, in particular precious metals, from
electronic scrap which is simple to effect and economically
advantageous.
[0021] In the light of these objectives and others which will
appear more evident hereunder, a process is provided, in accordance
with a first aspect of the present invention, for recovering
metals, in particular precious metals, from electronic scrap
comprising the treatment of scrap, either whole or grossly ground,
with an acid solution of cupric chloride and one or more alkaline
chlorides, in accordance with claim 1 enclosed.
[0022] Further characteristics of the invention are illustrated in
the subsequent claims.
[0023] In particular, the invention envisages the recovery of
metals through the treatment of electronic scrap such as printed
circuits having all the components and connectors still
installed.
[0024] In accordance with an embodiment, the process of the
invention comprises the leaching of metals on the part of solutions
of cupric chloride.
[0025] It has been verified that solutions of cupric chloride, in
the presence of an alkaline halide, in particular sodium and/or
potassium chloride exert a complexing and consequently stabilizing
action of the metallic species in solution, causing the dissolution
of the metals contained in the scrap, except for gold. The reaction
of interest is conveniently the following:
Me+n CuCl.sub.2.fwdarw.MeCl.sub.n+n CuCl
[0026] wherein Me comprises Fe, Zn, Pb, Ni, Co, Sn and other
metals. Specifically, a mole of metal selected for example from Fe,
Zn, Pb, Ni and Co, can react with n moles of cupric chloride
CuCl.sub.2, forming a mole of the relative metallic chloride and n
moles of cuprous chloride CuCl.
[0027] A solution comprising alkaline halides according to the
invention also allows other metals such as silver and copper to be
brought into solution. Said solution based on alkaline halides
proves to be particularly effective when it comprises at least one
oxidant.
[0028] Although it is present in electronic scrap in lower
quantities with respect to the other metals, gold represents the
greatest value contained therein, due to its high price.
[0029] From analyses effected on electronic scrap, it has been
verified that gold is present in the contacts, such as those
relating to the printed circuits and connection plugs and in the
chips. The gold fraction is generally equally subdivided among the
contacts, about 50%, and chips for the remaining 50%.
[0030] Following the treatment of the electronic scraps with an
acid solution of cupric chloride, in the presence of one or more
alkaline chlorides, other metallic values are then extracted, which
can be recovered through known processes, after which the solution
is regenerated to then be recycled and re-used again in the
dissolution unit of the metals, by means of simple oxidation in
air.
[0031] According to an embodiment, a solution of cupric chloride is
prepared, with one or more alkaline chlorides, having an acid pH,
conveniently ranging from 0 to 3, preferably from 0.5 to 2, and
having a varying content of cupric chloride (CuCl.sub.2), within
the range of 20 gr/l-50 gr/l, preferably 35 g/l.
[0032] The complexing effect is reinforced by the presence of
alkaline chlorides, such as NaCl and KCl in a relation of 100
g/l-250 g/l, preferably 150 g/l.
[0033] The electronic scrap, either whole or grossly ground, is
then immersed into said acid solution of cupric chloride at a
temperature ranging from 50.degree. C. to 105.degree. C.,
preferably from 70 to 90.degree. C. for a time of 1-5 hours,
preferably from 1 to 3 h, with the consequent attack and
dissolution of the metallic parts exposed to the solution, mostly
consisting of contacts not protected from polymeric painting. The
result of this operation is that all the electronic components,
normally protected from polymeric paint resistant to acid and
oxidizing attack, are detached from the scrap, together with the
recovery of the clean cards with the copper tracks protected by
paint, the recovery of other plastic parts mainly relating to the
connectors, and finally, the gold in the contacts in the form of
flakes dispersed in a fine inert powder and the solution containing
a mixture of metals among which the most important are copper,
silver, tin and iron.
[0034] After sieving, a liquid part, containing a suspension of
fine inert powder, is obtained, together with flakes of gold in the
under-sieve and a solid part in the upper-sieve.
[0035] The liquid part is conveniently filtered, obtaining, with
this simple operation, the separation of the gold powder, which
represents about 50% of the gold contained in the scrap treated,
together with a fine inert powder.
[0036] A fraction rich in plastic, i.e. the clean cards and other
plastic parts, and various components, is advantageously obtained,
on the other hand, by flotation from the solid part.
[0037] The chips containing the remaining quantity of gold,
accompanied by further copper, can be recovered from the separation
of the components, conveniently effected by means of magnetic
systems and/or Eddy Currents and subsequently by means of a
dimensional screening.
[0038] The separated chips are subsequently ground, not necessarily
into a fine form, so as to be able to expose the metallic part
contained therein, to allow the remaining quantity of gold present
to be recovered by means of a further immersion in the solution of
cupric chloride.
[0039] Possible parts which are extremely rich in copper, of the
ground electronic components can also be introduced into the
solution, to also enable the quantity of this metal contained
therein to be recovered.
[0040] The remaining metals dissolved therein are precipitated from
the filtered solution and subsequently extracted with traditional
methods.
[0041] The solution is typically treated in a reactor in which, by
means of an air bubbling system, the solution itself is oxidized to
enable it to re-exert its leaching action and is then re-admitted
to the dissolution unit.
[0042] The oxidation, which is preferably carried out at a
temperature higher than room value, advantageously within the range
of 70-90.degree. C., more preferably at about 80.degree. C., causes
the precipitation of iron and tin, as oxides, which are recovered
by filtration.
[0043] The water lost by evaporation is typically restored by the
addition of boiling water. The precipitate obtained by filtering
the solution is conveniently washed first with a diluted solution
of chlorides and subsequently with hot water and is finally
dried.
[0044] The washing liquids can then be collected in the final
oxidized solution.
[0045] The characteristics and advantages of a process for
recovering metals, in particular precious metals, from electronic
scrap according to the present invention will appear more evident
from the following illustrative but non-limiting description,
referring to the schematic drawings enclosed in which:
[0046] FIG. 1 shows a block scheme which illustrates an embodiment
of the recovery process of metals of the invention.
[0047] With reference to FIG. 1, a block scheme is shown, which
illustrates the main embodiment phases of a recovery process of
metals from electronic scrap.
[0048] In particular, the dissolution unit 10 is defined,
comprising an acid leaching solution of cupric chloride and
alkaline chlorides, preferably NaCl, in which the electronic scrap,
either whole or grossly ground, is immersed. The dissolution unit
is connected to a sieving unit 20, in turn connected to the
filtration unit 21, and separation unit by floatation 30, by means
of connection devices. The filtration unit 21 is connected to a
recovery unit of the silver 22 which, in turn, leads to a copper
recovery unit 23, connected to the leaching regeneration unit 11
which is connected to the dissolution unit 10, by means of
connection devices.
[0049] The figure also illustrates a separation unit by flotation
30 connected to the magnetic separation unit 31, in turn connected
to the separation unit with eddy currents 32, connected in turn to
the dimensional separation unit 33, which takes place with
mechanical systems. The unit 33 is then connected to the grinding
unit of the chips 34, in turn also connected to the dissolution
unit 10.
[0050] The units described above are connected to each other by
common connection devices such as, for example, conveyor belts,
mobile connection units, ducts suitable for transferring chemical
solutions and other means known to experts in the field.
[0051] According to an embodiment, the electronic scrap is fed to
the leaching unit 10 which contains a leaching solution comprising
cupric chloride and one or more alkaline chlorides dissolved.
[0052] At the end of the leaching phase, in which the metallic
parts exposed are mainly treated, the leaching solution comprising
cupric chloride and a metal chloride is transferred to the sieving
unit 20 in which the leaching solution is separated together with a
fine inert powder containing gold 40 which pass to the filtration
unit 21, from the other solid parts which pass to the separation
unit by flotation 30.
[0053] The fine inert powder containing gold 40 is advantageously
separated in the filtration unit 21 from the leaching solution
which then passes to the silver recovery unit 22. In this unit, the
silver 44 is precipitated and recovered from the leaching solution
which subsequently passes to the copper recovery unit 23. In this
unit, as in the previous one, the copper is precipitated from the
solution which is then brought to the regeneration unit of the
leaching solution 11. In this unit, air is conveniently bubbled
into the solution with the consequent formation of a precipitate
46, consisting in iron and tin oxide, which are recovered by
filtration. The oxidized solution which is purified by filtration
of the precipitate is again capable of exerting its leaching
activity and is then re-admitted to the dissolution unit 10.
[0054] The plastic fractions 41, consisting of clean cards,
connectors and other plastic parts are recovered in the separation
unit by flotation 30, from the solid parts coming from the sieving
unit 20. The remaining electronic components then pass to the
magnetic separation unit 31, from which a fraction of electronic
components rich in iron is recovered. The remaining components pass
to the separation unit with eddy currents 32, from which a fraction
rich in aluminum is obtained. Finally the remaining components are
brought to the dimensional separation unit 33, where they are
divided with mechanical systems. Non-useful fractions 47 and chips
are thus obtained. These pass to the grinding unit 34, in which
they are ground so as to expose the metallic parts contained
therein and are subsequently sent to the dissolution unit 10 for
the recovery of the remaining gold and copper fraction.
[0055] The following examples are provided for the solely
illustrative purposes of the present invention and should in no way
be considered as limiting its protection scope as defined in the
enclosed claims.
LEASHING EXAMPLE 1
Preparation of the Leaching Solution
[0056] 4 l of solution are prepared by mixing the following
components:
1 NaCl 600 g CuCO.sub.3 317 g HCl 36% 590 g Solution for the
leaching of the transformers 1 l
[0057] The titration of 10 cc of this solution with
Na.sub.2S.sub.2O.sub.3 0.1 N requires 8.9 cc (oxidants 0.89 N).
Leaching Process
[0058] A sample is attacked with the solution prepared, which
represents the average scrap sample, prepared according to the
following formulation:
2 Part of mixed contacts 25.7 g Smooth cards without components
118.0 g Cards with components 166.8 g Feeding of the test 310.5
g
[0059] The solution is brought to 75.degree. C. and the scrap is
then added. At this point, the reactor is put under stirring.
Samples are taken from the solution at intervals of 1 h to examine
the content of oxidants. After 2 h the test is stopped and the
liquid is separated from the solids to check the leaching effects.
The solid part is hand sorted, a magnetic separation is effected
and the following observations are made:
[0060] Card part: all clean with copper tracks under the paint
[0061] Magnetic part: no further leaching accepted
[0062] Non-magnetic part: there is a piece of non-painted
aluminum
[0063] Gold contact part: which are not completely detached
[0064] Fine part with gold threads.
[0065] The non-magnetic part (3) and that of the gold contacts (4)
is reinserted for leaching using a faster stirrer as the cards
which tend to block it have been removed. The leaching is restarted
and is continued for a further 2 h after which the dispersion is
passed over a 2 mm sieve, the >2 mm part (the piece of aluminum
is dissolved) is separated and filtered.
[0066] The following products are obtained:
[0067] 4.00 l of filtrate (titration: Na.sub.2S.sub.2O.sub.3 0.23
eq/l
[0068] KMnO.sub.4 0.76 eq/l)
[0069] 2.9 g of solid >2 mm as such
[0070] 2.05 g of dry solid <2 mm (which is attacked in aqua
regia)
[0071] The card section (1) amounts to 177.7 g of which 112.5
without components.
[0072] The non-magnetic section (3) >2 mm consisted of:
[0073] 9.2 g of chips
[0074] 5.2 g of cylindrical condensers
[0075] 3.6 g of various condensers
[0076] 19.7 g of plastic (which is then attacked in aqua regia; it
seems perfectly clean)
[0077] 2.3 g of various material
[0078] The magnetic part (2) consisted of:
[0079] 23.7 g of transformers
[0080] 6.0 g of resistances
[0081] 4.9 g of pieces which looked like small square condensers
but which actually proved to be pseudo-transformers consisting
of:
3 1.7 g of iron 34.7% 1.7 g of copper 34.7% 0.8 g of plastic 16.3%
0.7 g of plastic with copper 14.3%
[0082] small square condensers
[0083] 1.1 g of chips
[0084] 0.8 g of various material
[0085] 9.7 g of slightly magnetic parallelepiped condensers
[0086] A small piece of these seemed golden and was put under
leaching.
[0087] The non-magnetic part is crushed in a crusher until it has
been reduced to dimensions of <1 mm. The condensers are crushed
but do not break. The same thing also occurs with the "soft
plastics". All the rest tends to crumble.
[0088] The magnetic part is sieved on a sieve with rectangular mesh
of 3-4 mm.times.30-40 mm allowing the condensers, resistances and
chips to pass and leaving the transformers and pseudo-transformers
on the upper-sieve.
[0089] The under-sieve is then passed into the crusher (vise) and
the following products are recovered from the separation:
[0090] Magnetic part with copper and iron
[0091] Magnetic and non-magnetic part with dimensions >5 mm
(plastic and condensers)
[0092] Crumbled part with metals (chips, etc.) which amounts to
18.9 g (material lost during the operation in the crusher)
[0093] An attack in 1 l of solution previously used for other tests
is effected on this latter fraction (titration:
Na.sub.2S.sub.2O.sub.3 0.49 eq/1-KMnO.sub.4 0.43 eq/l).
[0094] After 1.5 h the reaction is terminated and the product is
filtered. The filtration which was initially good, slowly
deteriorates, becoming extremely poor. The following products
however are recovered:
[0095] 1.02 l of filtrate
[0096] 15.8 g of dry residue which, as such, weighed 18.5 g
(humidity 14.6%)
[0097] The residue is attacked with aqua regia for analytical
purposes.
[0098] Analysis, Balancing and Calculations
[0099] Analysis of the solutions gave the following result:
4 Ag Au Al Cu Fe Ni Pb Sn Zn Analysis (solutions) (mg/l) (mg/l)
(g/l) (g/l) (g/l) (mg/l) (g/l) (g/l) (g/l) Initial solution (first
part) 4.00 l 10.0 0 0.0 57.0 0.119 0.045 0.0 0.0 0.095 Final
solution (first part) 4.00 l 26.5 0 3.04 62.2 1.072 0.209 1.20 2.32
0.305 Initial solution (second part) 1.00 l 24.6 0 2.90 62.6 1.095
0.209 1.21 2.26 0.304 Final solution (second part) 1.02 l 83.0 0
2.98 58.2 2.176 0.282 1.22 2.13 0.307
[0100]
5 Ag Au Al Cu Fe Ni Pb Sn Zn Total Quantity (solutions) (mg) (mg)
(g) (g) (g) (g) (g) (g) (g) (g) Initial solution (first part) 40 0
0 228 0.476 0.18 0 0 0.3784 52.41 Final solution (first part) 106 0
12.152 248.8 4.288 0.836 4.8 9.284 1.2192 Difference first part 66
0 12.152 20.8 3.812 0.656 4.8 9.284 0.8408 Initial solution (second
part) 24.6 0 2.90 62.60 1.10 0.21 1.21 2.26 0.30 -1.88 Final
solution (second part) 84.66 0 3.04 59.36 2.22 0.29 1.24 2.17 0.31
Difference second part 60.06 0 0.138 -3.236 1.125 0.079 0.034
-0.086 0.009
[0101]
6 Ag Au Al Cu Fe Ni Pb Sn Zn Analysis (solids) (g/t) (g/t) (%) (%)
(%) (%) (%) (%) (%) End resid. second leaching 2.05 g 1100 2100
n.a. 14.05 1.30 0.77 0.51 n.a. 0.11 Plastic (>2 mm non magnetic)
19.7 g 19 3 n.a. 2.30 0.006 0.06 n.d. n.a. 0.12 Last leaching
residue 15.8 g 70 450 0.37 1.45 0.51 0.08 0.13 0.81 0.012
LEASHING EXAMPLE 2
Preparation of the Leaching Solution
[0102] 4 l of solution are adopted, already used in other tests and
partially re-oxidized with air, to verify the possibility of
operating with a recycled solution. The titration of 10 cc of this
solution with Na.sub.2S.sub.2O.sub.3 0.1 N requires 7.1 cc
(oxidants 0.71 N) with KMnO.sub.4 0.1 N requires 2.0 cc (reducing
agents 0.20 N).
Preparation of the Leaching Solution
[0103] A sample is attacked with the solution prepared, where there
are no empty cards because they do not give any indication. The
sample was prepared according to the following formulation:
7 Cards with gold contacts 64.6 g Cards with components 217.5 g
Feeding of the test 282.1 g
[0104] Also in this case, the solution is brought to 75.degree. C.
and the scrap is then added. At this point, the reactor is put
under stirring. Samples are taken from the solution at intervals of
1 h to examine the content of oxidants. After 2.5 h the test is
stopped and the liquid is separated from the solids to check the
leaching effects. The solid part is hand sorted, a magnetic
separation is effected and the following products are
separated:
[0105] 4.0 l of filtrate (titration: Na.sub.2S.sub.2O.sub.3 0.45
eq/l
[0106] KMnO.sub.4 0.48 eq/l)
[0107] 2.0 g of dry residue which, as such, weighed 5.00 g
(humidity 60.0%)
[0108] 81.8 of cards (including 63.7 g of cards already
removed)
[0109] 34.8 g of plastic
[0110] 101.7 g of magnetic material comprising:
[0111] 57.1 g of transformers
[0112] 29.5 g of bobbins
[0113] 9.2 g of condensers
[0114] 4.2 g of chips
[0115] 1.0 g of resistances
[0116] 0.7 g of various material
[0117] 21.5 g of non-magnetic material comprising:
[0118] 8.1 g of chips
[0119] 3.8 g of cylindrical condensers
[0120] 4.3 g of various condensers
[0121] 5.3 g of various material
Analysis, Balancing and Calculations
[0122] Analysis of the solutions gave the following result:
8 Ag Au Al Cu Fe Ni Pb Sn Zn Analysis (solutions) (mg/l) (mg/l)
(g/l) (g/l) (g/l) (mg/l) (g/l) (g/l) (g/l) Initial solution 4.00 l
27.0 0 0.303 55.0 1.53 0.647 0.62 0.73 0.872 Final solution 4.00 l
50.5 0 0.45 57.1 2.85 1.105 2.22 3.73 0.959
[0123]
9 Ag Au Al Cu Fe Ni Pb Sn Zn Total Quantity (solutions) (mg) (mg)
(g) (g) (g) (g) (g) (g) (g) (g) Initial solution 108 0 1.212 220
6.12 2.588 2.48 2.916 3.488 34.95 Final solution 202 0 1.80 228.4
11.4 4.42 8.88 14.928 3.836 Difference 94 0 0.588 8.4 5.28 1.832
6.4 12.012 0.348
[0124]
10 Ag Au Al Cu Fe Ni Pb Sn Zn Analysis (solids) (g/t) (g/t) (%) (%)
(%) (%) (%) (%) (%) Leaching final residue 2 g 2100 2010 n.a. 20.9
2.61 0.48 0.98 n.a. 0.35
LEACHING EXAMPLE 3
Preparation of the Leaching Solution
[0125] 4 l of solution are prepared, having the following
formulation:
11 NaCl 800 g CuCO.sub.3 400 g HCl 36% 720 g
[0126] The titration of 10 cc of this solution with
Na.sub.2S.sub.2O.sub.3 0.1 N requires 8.9 cc (oxidants 0.89 N).
Leaching Process
[0127] A sample is prepared according to the following
formulation:
12 Cards with gold contacts 33.0 g Cards without gold contacts
248.2 g Feeding of the test 281.2 g
[0128] Also in this case, the solution is brought to 75.degree. C.
and the scrap is then added. At this point, the reactor is put
under stirring. Samples are taken from the solution at intervals of
1 h to examine the content of oxidants. After 2 h the test is
stopped, the clean cards (now without any component) are removed
together with the transformers (by magnetic separation), 426.7 g of
other cards are added and the process is continued for a further
2.5 h. At the end of this period, the liquid is separated from the
solids to check the leaching effects. The solid part is hand
sorted, a further magnetic separation is effected and the following
products are separated:
[0129] 4.0 l of filtrate (titration: Na.sub.2S.sub.2O.sub.3 0.61
eq/l
[0130] KMnO.sub.4 0.36 eq/l)
[0131] 2.0 g of dry residue
[0132] 107.7 of cards (first phase)
[0133] 408.7 of cards (second phase)
[0134] 18.4 g of plastic (there is still metal which does not
however seem to be gold. By attack with aqua regia it is
demonstrated that all the gold was detached during the leaching
with CuCl.sub.2)
[0135] 101.0 g of magnetic material comprising:
[0136] 51.5 g of transformers (6)
[0137] 39.3 g of bobbins (8)
[0138] 5.9 g of condensers
[0139] 3.0 g of chips
[0140] 1.3 g of resistances
[0141] 17.1 g of non-magnetic material comprising:
[0142] 7.3 g of chips
[0143] 4.9 g of cylindrical condensers
[0144] 4.9 g of parallelepiped condensers
Analysis, Balancing and Calculations
[0145] Analysis of the solutions gave the following result:
13 Ag Au Al Cu Fe Ni Pb Sn Zn Analysis (solutions) (mg/l) (mg/l)
(g/l) (g/l) (g/l) (mg/l) (g/l) (g/l) (g/l) Initial solution 4.00 l
10.0 0 0.000 54.9 0.00 0.000 0.00 0.00 0.000 Final solution (first
phase) 4.00 l 25.5 0 0.203 57.9 0.87 0.075 1.47 3.54 0.099 Final
solution 4.00 l 28.1 0 0.281 60.6 0.92 0.082 1.69 3.54 0.102
[0146]
14 Ag Au Al Cu Fe Ni Pb Sn Zn Total Quantity (solutions) (mg) (mg)
(g) (g) (g) (g) (g) (g) (g) (g) Initial solution 40 0 0 219.6 0 0 0
0 0 49.32 Final solution (first phase) 102 0 0.81 231.6 3.50 0.300
5.88 14.16 0.397 Final solution 112 0 1.12 242.4 3.67 0.328 6.76
14.16 0.406 Difference (final - initial) 72.4 0 1.124 22.8 3.67
0.328 6.76 14.16 0.406
[0147]
15 Ag Au Al Cu Fe Ni Pb Sn Zn Analysis (solids) (g/t) (g/t) (%) (%)
(%) (%) (%) (%) (%) Leaching end residue 2 g 2100 2010 n.a. 20.9
2.61 0.48 0.98 n.a. 0.35
* * * * *