U.S. patent application number 13/716631 was filed with the patent office on 2013-07-04 for method for incinerating carbon-containing dry metallic ash.
This patent application is currently assigned to HERAEUS PRECIOUS METALS GMBH & CO. KG. The applicant listed for this patent is Heraeus Precious Metals GmbH & Co. KG. Invention is credited to Norbert Ritschel, Jan Schapp, Steffen Vo.
Application Number | 20130167760 13/716631 |
Document ID | / |
Family ID | 47290553 |
Filed Date | 2013-07-04 |
United States Patent
Application |
20130167760 |
Kind Code |
A1 |
Vo ; Steffen ; et
al. |
July 4, 2013 |
METHOD FOR INCINERATING CARBON-CONTAINING DRY METALLIC ASH
Abstract
The invention relates to a method for incinerating
carbon-containing dry metallic ash and a pertinent device. The
method comprises the steps of p) adding the metallic ash into a
trough; q) aerating with ambient air from above, and concurrently,
at least for part of the time, r) injecting air and/or oxygen
through the trough hearth; s) establishing the ignition
temperature; t) stirring of the metallic ash by means of a suitable
tool; u) whereby the carbon content is reduced to less than 3%; and
whereby steps b), c), and d) can proceed concurrently or in
alternating order or pairs or all of these steps can proceed
concurrently; step d) can just as well proceed selectively in
partial quantities of the metallic ash; and whereby the reverse
transport of ash through the trough hearth is prevented, whereas
the supply of air and/or oxygen is maintained.
Inventors: |
Vo ; Steffen; (Limeshain,
DE) ; Schapp; Jan; (Frankfurt, DE) ; Ritschel;
Norbert; (Kleinkahl, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Heraeus Precious Metals GmbH & Co. KG; |
Hanau |
|
DE |
|
|
Assignee: |
HERAEUS PRECIOUS METALS GMBH &
CO. KG
Hanau
DE
|
Family ID: |
47290553 |
Appl. No.: |
13/716631 |
Filed: |
December 17, 2012 |
Current U.S.
Class: |
110/251 ;
110/255; 110/346 |
Current CPC
Class: |
C22B 11/023 20130101;
C22B 7/00 20130101; Y02P 10/20 20151101; C22B 1/02 20130101; Y02P
10/214 20151101; C22B 7/001 20130101 |
Class at
Publication: |
110/251 ;
110/255; 110/346 |
International
Class: |
C22B 7/00 20060101
C22B007/00; C22B 1/02 20060101 C22B001/02 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 22, 2011 |
DE |
10 2011 122 139.9 |
Claims
1. A method for incinerating carbon-containing dry metallic ash,
the method comprising the steps of: a) adding the metallic ash into
a trough; b) aerating from above with ambient air; c) injecting air
and/or oxygen through a hearth of the trough; d) establishing an
ignition temperature; e) stirring of the metallic ash by means of a
suitable tool; f) whereby a carbon content of the metallic ash is
reduced to less than 3%; and whereby steps b), c), and d) can
proceed concurrently or in alternating order or pairs or all of
these steps can proceed concurrently; and steps b) and c) proceed
concurrently, at least for part of the time; step d) can just as
well proceed selectively in partial quantities of the metallic ash
wherein a reverse transport of metallic ash through the hearth of
the trough is prevented, whereas the supply of air and/or oxygen is
maintained.
2. A device, for implementing the method according to claim 1,
comprising g) a trough (a1) h) having a level hearth (b2), i)
whereby hearth (b2) comprises openings (c3), j) with metal fibers
(d4) being arranged below hearth (b2) and forming a space (d4a),
which is closed in downward direction through k) another trough
hearth (e5) that is arranged parallel to hearth (b2) l) having
further openings (f6) that are arranged at an offset from said
openings (c3), whereby m) hearth (e5) and hearth (b2) are connected
by means of connecting means (g7) in such manner that metal fibres
(d4) are firmly occluded, and n) a space (h8) is provided below
hearth (e5) to which o) means (i9) for supplying air or oxygen are
provided.
3. A device according to claim 2, the device comprising: j) flow
guides for optimising air circulation are provided in space
(h8).
4. A device according to claim 2, wherein the metal fibers (d4) are
present as woven material, fabric, fleece or knitted material.
Description
[0001] The invention relates to a method for incinerating
carbon-containing dry metallic ash and a device for implementing
said method.
[0002] Metallic ash is understood to be the product of primary
incineration of recycling material that contains plastic materials
and solvents and is to be reprocessed for its noble metal content.
Noble metals can be present in recycling material of this type
either in elemental or chemically bound form, e.g. as salts or
oxides. The metallic ash can therefore also contain these
substances.
[0003] Following primary incineration/carbonisation, said ashes
still contain substantial fractions of carbon that should be
removed before further recycling steps and/or should be reduced to
a fraction of less than 3%.
[0004] US4360380/DE3134733A1 specifies a metal recycling method, in
which the incineration of organic fractions is carried out at
temperatures below the slag formation temperature of the silicate
fractions. This is aimed at preventing valuable metals from being
included in glass:
[0005] "The slag formation temperature of quartz is approx.
760.degree. C. Accordingly, if the incineration proceeds at a
temperature between 315 and 480.degree. C. and in the presence of
sufficient oxygen or of an excess of oxygen with adequate stirring,
it has been found that the organic fraction is incinerated without
undesirable silicates being formed."
[0006] Accordingly, DE3134733A1 describes a method having the
following features:
[0007] "Method for recycling selected metal fractions from
quartz-containing sludges by incinerating the sludge in order to
disintegrate organic fractions followed by acidic leaching of the
ash and hydro-metallurgical recovery of the metal fractions from
the remaining solid and liquid residues, whereby the incineration
is carried out at a temperature below the slag formation
temperature of silicates in order to prevent metal fractions from
being occluded in glass matrices that are not attacked by the
subsequent acidic leaching and the hydrometallurgical procedural
steps."
[0008] According to DE3134733A1, the process is carried out in a
furnace. The efficiency of the process is said to be increased
through stirring and supplying air: "Moreover, it has been evident
that stirring of the sludge aimed at keeping the temperature at an
even level throughout and increasing the access of oxygen to the
organic material, improved the method significantly. Obviously,
stirring or forced aeration are used in one way or another in many
sludge incineration facilities and are not considered to be novel
features as such".
[0009] In contrast, the present invention provides a method for
incinerating carbon-containing slags in open troughs through
overturning on air and includes additional aeration from below, as
described in claim 1. Consistent with DE3134733A1, the prior art is
the incineration in open troughs with frequent overturning by means
of rakes. Additional aeration from below according to the invention
surprisingly reduces the duration of the incineration process by 50
to 80%. This is more than an additive effect and rather represents
a surprising synergism. Additional aeration from below according to
the invention surprisingly reduces the duration of the incineration
process by 50 to 80%. This is more than an additive effect and
rather represents a surprising synergism. It also needs to be noted
that the material burns more rapidly after ignition. The
overturning by means of rakes is kept for expedient reasons to
ensure that no crusts are formed at the hearth region of the
troughs or on the surface of the incinerated goods. The carbon
content is reduced to less than 3%.
[0010] The overturning by means of rakes is kept for expedient
reasons to ensure that no crusts are formed at the hearth region of
the troughs or on the surface of the incinerated goods. The carbon
content is reduced to less than 3%.
[0011] Another option is to enrich the air, which is blown-in from
below, with oxygen in order to improve the efficiency of
incineration.
[0012] According to an essential feature of the method according to
the invention, any reverse transport of ash is prevented whereas
the supply of air and/or oxygen is maintained.
[0013] In detail, the method comprises the steps of: [0014] a)
adding metallic ash into a trough; [0015] b) aerating from above
with ambient air; [0016] c) injecting air and/or oxygen through the
trough hearth; [0017] d) establishing the ignition temperature;
[0018] e) stirring of the metallic ash by means of a suitable tool;
[0019] f) whereby the carbon content is reduced to less than 3%;
[0020] whereby steps b), c), and d) can proceed concurrently or in
alternating order or pairs or all of these steps can proceed
concurrently; [0021] step d) can just as well proceed selectively
in partial quantities of the metallic ash; and the reverse
transport of ash through the trough hearth is prevented, whereas
the supply of air and/or oxygen is maintained.
[0022] In a convenient embodiment, the incineration process is
carried out in a multiple hearth incinerator at the open top of the
trough exposed to ambient air and by means of injecting air from
below. The time for the carbon fraction to reach a level below 3%
is 2 hours.
[0023] The invention also relates to a device for implementing a
method, according to claim 2, of the type described above in the
form of a container, preferably a trough, that comprises a hearth
that is aerated from below.
[0024] The hearth comprises means preventing the ash from dropping
through the grate, whereas the supply of air and/or oxygen from
below is not obstructed.
[0025] Preferably, the invention provides a hollow double-hearth
trough having an upper hearth and a lower hearth. Openings, such
as, e.g., holes or slits, in the upper and lower hearth ensure the
supply of air from below, whereas metal fibres, such as a wire mesh
or similar material, in the space between the hearths ensures that
the ash cannot fully drop through the two hearths. In addition, it
is expedient for the openings to be situated not directly across
from each other, which results in favourable flow conditions from
the start.
[0026] Overall, the feature of having a metal fibre-containing
double-hearth trough provides a surprisingly simple solution
allowing the desired substance transport from below to proceed
while sufficiently impeding the undesired substance transport from
above.
[0027] Flow guides are another expedient feature that further
optimises the flow conditions provided they are situated
properly.
[0028] The fibres can be present as woven material, fabric,
non-woven fabric or knitted material. Preferably, they are
knitted.
[0029] FIG. 1 shows a preferred embodiment of the device.
[0030] This comprises [0031] a) a trough a1 [0032] b) having a
level hearth b2, [0033] c) whereby hearth b2 comprises openings c3,
[0034] d) with metal fibres d4 being arranged below hearth b2 and
forming a space d4a, which is closed in downward direction through
[0035] e) another trough hearth e5 that is arranged parallel to
hearth b2 [0036] f) having further openings f6 that are arranged at
an offset from said openings c3, whereby [0037] g) hearth e5 and
hearth b2 are connected by means of connecting means g7 in such
manner that metal fibres d4 are firmly occluded, and [0038] h) a
space h8 is provided below hearth e5 to which [0039] i) means i9
for supplying air or/and oxygen are provided.
[0040] Flow guides for optimising the air circulation can be
provided in space (h8).
[0041] The metal fibres (d4) can be present as woven material,
fabric, fleece or knitted material. Preferably, they are
knitted.
* * * * *