Note: Descriptions are shown in the official language in which they were submitted.
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PAT 90 251
14.05.1990/FE
- 0888Z -
BASF Lacke ~ Farben AXtiengesellschaft, Munster
Process and apparatus for _ dis~osinq of packinq
recep~acles
The present invention relates to a process fo~
disposing of packing receptacles, in which
1. the packing receptacles are opened and reduced in
size by means of a size-reduction apparatus,
2. the liquid and any fine-particled solid residual
contents are separated, collected and passed on
or a suitable disposal,
3. any gases produced are rarefied and caxried away
by ~ constant airstream and
4. the emptied and size-reduced packing receptacles
are collected.
The present invention also relates to an ap~
paratus for carrying out this process.
Packing receptacle3 often contain environmentally
hazardou~ product~, for example highly in1ammable and/o.r
toxic liguids and/or gase Such receptacles cannot
simply be landfilled after use like conventional house-
hold garbage, but have to be passed on for a segregated
waste disposal,
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In addition, the material of the packing receptacles
represents a valuable raw material which sho~ld be passed
on for reuse wherever possible. However, a cleaning of
such packing receptacles and subsequent reuse as such is
only economically viable if a certain size of the packing
receptacles (for example 200 1 barrel) is reached. A
reuse of smaller packing receptacles by rec~very of the
raw materials is possible only if the liguid residual
contents contained in the containers are first completely
removed and passed on for a proper disposal.
A process for disposing of receptacles which con-
tain aerosols or propellants, inflammable gases or ~oxic
chemicals is described for example in US Patent
4,356,981. There the receptacles for disposal are first
of all destroyed by a shredder~ The residual constituents
~hen drop down onto a conveying means with a perforated
conveying belt. The liquid residual constituents drip
down through the holes in the conveyor b~lt and are
collected in a pan lying underneath and emptied via a
liquid outlet. The conveyor belt is axranged within a
housing which is substantially seale~ off from the
outside and through which an air flow is passed~ ~y means
of a vacuum fan, gaseous con~tituents are carried away in
a controlled manner by this air stream via an extraction
openins. However, this pxocess described in US Patent
4,356,981 is uitable only for a precleaning of the size-
reduced packing receptacles. For instance, the upper side
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of the parts on the conveyor belt remain uncleaned, since
liquid can drip only fxom the underside of the parts.
Very viscous substances cannot be removed at all. None-
theless, owing to rele~ant legal regulations (laws on
waste and water pollution laws), it is essential for use
of the packing receptacles that all residual contents
able to flow or drip have been removed completely (cf.
publications of the Informationskrei.s der Verwertung
entleerter Blechgebinde - Information Group for the Use
of Emptied Sheet Metal Containers). What is also dis-
advantageous about this process is tha-t the pore openings
in the conveyor belt clog after a relatively shor~ time
and therefore the conveyor belt has to he cleaned fre-
quently.
It is also known, from German Patent 3,713,477,
to di pose of such packing receptac}es by the receptacles
first of all being reduced in size in a size-reduction
installation to which nitrogen under positive pressure is
admitted and the residual constituents collected in a
waste container. Howev~r, even with this process, a
complete removal of the residual constituents from the
packaging receptacle material is not po~sible. What is
also disadvantageou~ about this process is that, owing to
the positive nitrogen pressure, losses of the gaseous
conæti~uents occur and, even in spite of a protective gas
atmosphere, a certain risk of explosion remains.
2~a70
Finally, various appa.rakuses for the size reduc~
tion of aerosol cans in which the xisk of explosion due
~o the gaseous contents released during the size reduc-
tion of the aerosol cans is avoided by special precau-
tions are known for example from the patent specifica-
tions US Patent 3,828,976, US Patent 3,303,968, US Patent
3,438,548 and US Patent 3,333,735. :How, on the other
hand, residual contents able to flow or drip are to be
removed completely from the parts of th~ packing recept-
acles is not described.
It is consequently an object of the present
invention to provide a process for disposing of packing
receptacles by which receptacles containing environment-
ally hazardous liquid, pasty and solid substances (for
example remains of coating~) can be reconditioned by
means of a very simple and cost-effective me~hod. In par-
ticular, it should be ensured by this process that the
size-reduced receptacles obtained are freed completely of
all residual contents able to flow or drip as well as
such contents giving off gas and thus the receptacle
material can be passed on for reuse.
This object is achieved according to the
invention by a
process for disposing of packing receptacles, in which
1. the packing receptacles are opened and
reduc~d in size by means of a size-reduction
apparatus,
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2. the liquid and any fine-particled solid
residual contents are separated, collected
and passed on for a suitable disposal,
3. any gases produced are rarefied and carried
away by a constant airstream and
4. the emptied and size-xeduced packing recept-
acle parts are collected.
~,
the packing receptacles are passed through at lea~ one
rotating screening drum and a heated gas or ga~ mixture
is admitted to the size-reduction apparatus/and/or the
screening drum.
The present invention also r~ ates to an ap-
paratus for carrying out this proce ~.
The process according t ~ the invention has in
particular the ad~antage that ~ll the residual contents
able to flow or drip as wel~ as such contents giving off
gas can be removed comp ~ ely.
At the same ~ e, all contents not flowing or
dripping away of t ~ir own accord can also be removed by
first of all ~ing dried on and then substantially
detached by ~ e contacting (rubbing) in the drum, i.e.
e~en solid/ ontents can be substantially removed.
~ he process has provided a saEe, simple and
inex ~ nsive possibility of making even small packing
r7~eptacles suitable for reuse, irrespective oE size and
'S~TaE~E3
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In the process, following their size reduction,
the packing receptacles are passed th:rough at least one
rotating ~creening drum and a gas or gas mixture heated
to a temper ture of from 40 to 150C, prefera~ly from 80
to 120C~ is admitted to the size-reduction apparatus
and/or the screening drun.
A device for disposing of propellants and/or
refrigerants i9 indeed known from EP-A1-336-254, in which
device a circulating air stream heated to approximately
40C is introduced into a size-reduction ch~mber. How-
ever, the known device is not used for disposing of
packing receptacles contaminated with liquid residual
- contents, but for the disposal and recovery of pro-
pellants and/or refrigerant , e~pecially chlorofluoro-
carbon3, from foams and/or plastics. The circulating air
is heated in order to remove the propellants and/or
xefrigerant~ in the gaseous state.
The present invention also relates to an appa-
ratus for carrying out this process.
~he process according to the inve~tion has in
particular the advantage that all the residual contents
able to flow or drip as well as such contents giving of~
REpLAcEMEN~r ~HEET
..
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gas can be removed completely.
At the same time, all contentq not flowing or
dripping away of their own accord can also be removed by
first of all being dried on and then substantially
detached by the contacting (rubbing) in the drum, i.e.
even solid contents can be substantially removed.
The process ha~ provided a safe, simple and
inexpensive po3sibility of making even small packing
receptacles suitable for reuse7 irrespective of size and
shape.
REPI,ACEMENT SHEE
. . .
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The apparatus and the process according to the
invention are explained in urther detail below.
In order to ensure a safe and environmentally
friendly disposal of packing receptacles, the entire
apparatus from ~he fPed into the size-reduction installa-
tion through to the discharge from the screening drum or
packing press is cl~sed off from the surroundings. In
order to avoid the risk of explosions during the opera-
tion of the installation, the air in the installation is
constantly extracted, for example by means of an induced
draft or the like, and thus a negative pressure is
produced in the installation. At the same tLme, the air
stream is regulated in such a manner that the gases
released duri~g the si~e reduction of the packing recept-
lS acles and the further removal of the contents are trans-
ported away very ~uickly, thus permitting safe operation
of the installation. It is preferred if the air stream
is regulated in ~uch a manner that an at least 8-fold air
exchange per minute is ensured in the parts of the
apparatus under negative pressure (si~e-reduction ap-
paratus and drum), in order in this way to reduce ~he
risk of explosions. It i~ particularly preferred if a
much higher air exchange is set, for example a ~0-fold or
e~en greater air exchange per minute. For a proper
~5 disposal of the waste gases produced, the waste air from
the installation is either cleaned by suitable filters,
for example activa~ed carbon filters, or passed on to an
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incineration installation. If a combustion of the gases
is not possible owing to theix chemical composition, not
only a filter but also a condenser with following ap-
paratus for fractionated distillation may be fitted at
the end of the waste gas line.
This avoidance of explosions by a frequent air
change offers the advantage over making the atmosphere
inert, for example by means of nitrogen gas, that the
installation is not operated under positive pressure but
continuously under negative prassure without a sluice
system, thereby avoiding emissions.
To reduce the risk of explosions urther, :it may
be appropriate to install additionally an active ex-
plosion suppression system with pressure sensors and an
automatic powder extinguishing system. Explosion flaps
are in any case to be provided. These systems are
generally known and therefore need not be explained in
any further detail here.
To dispose of the packing receptacles, which may
ei~her be at leas~ partially empty or else still com-
pletely full, it is preferred if the receptacles are
~irst of all presorted according to the packing recept-
acle material, such as plastic, tin plate, black plate
and aluminum. ~hereafter, they are passed on to a size-
reduction apparatus, for example by means of a bucketelevatorl a ~lt con~eyor or by means of o~her suitable
charging device~.
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In the si~e-reduction appar~tus, the receptacles
are opened and reduced in siza, preferably by means of
motor-driven, slow-running cutting tools, for example by
means of cutting rollers. As a result, the accessible
surface of the packing rec~ptacles i.s increased in size
and remains which are able to flow can drip away ir-
respective of the positlon. The p~c}cing receptacles are
in this case usually reduced in size in the form of
strips, the strip width generally being from 20 to 50 mm.
Size-reduction apparatuses are known per se and described
for example in the publications German Patent 3,713,477
and US Patent 4,35b,9810 All other known size-reduction
apparatuses are also suitable. Of course, the particular
size-reduction apparatus is to be adapted as usual to the
type and size of the packing receptacles to be reduced in
si.ze. Furthermore, it is also possible to combine a
plurality of size-reduction apparatuses in the form of a
cascade, in order for example in this way to reduce the
packing receptacles first of all to a preliminary size
and then reduce them fuxther in ~ize.
The size-reduction apparatus is followed ~y at
least one rotating screening drum, which is preferably
arranged underneath the size-reduction apparatus and
pointing down at an angle and into which the packing
receptacles enter in the form of chips, for example via
a chute. The connection between ~ize-reduction apparatus
and screening drum is to be made gas-tight. Suitable
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screening dr~ms generally have a diameter of from 1 to 3
m, the particular diameter being dependent on the size
of the cutting frame and of the chut:e. Substantially
bigger or substantially smaller screening drums may also
be used. For cleaning the holes in the screening drum,
the latter may be advantageously combined with a spiked
roller.
The automatic cleaning-off of the size-reduced
packing receptacles in this screening drum is assisted by
the rotation of the drum. On the one hand, the rotational
speed of the screening drum i5 not to be set too high
here, so as to ensure that the remains which are able to
flow drip off. Rotational speeds of ~ 5 rpm are generally
suitable for this. On the other hand, the rotational
speed must be high enough to ensure that the dried, solid
residual contents are cleaned off by rubbing in the drum.
Furthermore, the rotational speed is dependent on the
degree of filling. Usually rota~ional speeds of > 2 rpm
are suitable for this. Owing to these different require-
ments for the rotational speed of the screening drum,
preferred embodiments comprise a combination of at least
two screening drums having different rotational speeds or
a graduation of the drum diameters with possi~ly also an
angular cross-section.
If a plurality of screening drums are arranged in
succession, the firs~ screening drum directly downstream
of the size-reduction apparatus rotates ~lowly,
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preferably at a speed of less than or equal to 5 rpm,
whereas the second screening drum rotates faster, prefer
ably at a speed of greater than or equal to 2 rpm.
The same effect can be achieved by graduating the
` 5 drum diameters.
It is essential for the invention that a heated
gas or gas mixture is admitted to the screening drum. The
gas or gas mixture is generally at temperatures of from
40 to 150C, preferably from 80 to 120C, the temperature
of the gas or gas mixture always being below the ignition
temperature of the contents. The waste air from an
incineration installation can be used for example as the
heated ga~ mixture. The admission of hot air in this case
firstly achieves an improvement in the flow of ~he liquid
residual substances. A drying and complete outgassing of
the residual sub~tance~ takes place in a second phase,
enabling attached matter to burst.
The admission of hot air generally takes place in
the region of the first third of the screening drumO
However, hot air can also be admitted advantageously to
the size-reduction apparatus. In addition, it is of
course also possible to feed the hot air in in the region
between the size-reduct:ion apparatus and the screenins
drum. Both the liquid separated from the packing recept-
acle partR in the size reduction apparatus and the liquid
separated from the said parts in the screening drum is
caught for example in a pan or passed on for a suitable
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disposal, for example incineration, by a slush pump or
the like.
In cases where the receptacles have a high liquid
content, it is also possible to inject for example
between the working chamber of the size-reduction ap-
paratus and the liquid fractiona~or (for example upstream
of the first screening drum~ a liquid-hinding medium,
such as for example sawdust.
As an alternative to this, it may be advantageous
in some cases, depending on the contents, to inject one
or more organic solvents into the screening drum and~or
the working chamber of the size-reduction appara~us. To
save costs, already used or contaminated solvents, for
example wash solutions or the like, which would have to
be disposed of in any case may be advantageously used for
this purpose. The solvents are then passed on together
with the dissolved liquid residual contents for a
specific disposal, as already mentioned.
~he size-reduced and cleaned packing receptacle
parts may be collected directly downstream of the screen-
ing drum and passed on for reuse. ~o reduce ~he trans
porting volume of the size-reduced parts, it i~ preferred
however to compress the parts in a press following the
screening drum and only then collect them in containers
and pass them on for reuse.
The apparatus in question for disposing of
packing receptacles is preferably combined with a
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hazardous waste incineration installation. Along with
simple disposal of the waste air and liquids produced,
this has the further advantages ~hat very high air
exchanges in the installation, of for example 20-fold air
exchanges/min, are easy to accomplish and there is no
longer any need for expenditure on fans and filters. In
addition, the waste heat from the incineration installa-
tion can be used for the hot air feeding.
An exemplary embodiment of the invention is
explained in further detail below with reference to the
drawing. The figure shows an apparatus for a disposing
of packing receptacles in diagrammatic representation.
It shows the housing 1, the belt conveyor 2, the
filling hopper 3, the size-reduction apparatus with
working chamber 4 and cutting rollers 5, the chute 6, the
screening drum with graduated drum diameter, comprising
a liquid fractioning section 7, an integra~ed conveying
screw 8, a contacting section ~, a section 10 for separ-
ating the sheet metal from the solid residues and a metal
discharge 11, the collecting container 12 for liquids,
the container 13 for solid residues and the collecting
container 14 for the cleaned packing receptacle parts. To
carry out the process, the packing receptacle~ of the
s~me material, for example tin plate, collected in a
container are passed on by means of a belt conveyor 2 to
the filling hopper 3. From there, the packing receptacles
pass into the working chamber 4I where they are opened
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and reduced in size with the aid of cutting rollers 5.
The size-reduced packing receptacle parts pass via a
chute 6 into the fractioning section 7 of the drum,
designed as a screening drum. This screening drum 7 has
a diameter of abou~ 3 m and a length of about 1.5 m. The
length and diameter of this screening drum 7 are chosen
in this case to be large enough for the height of the bed
not to be too high, in order to ensure that the liquids
can drip off easily. Due to the rotation of the screening
drum 7, remains which are able to flow can drip off
irrespective of the position. These remains which are
able to flow are collected in the container 12. In order
to prevent the holes in the screening drum from clogging,
a spiked roller 15 is arran~ed above the screening drum.
The packing receptacle parts freed of the
r~mains which are able to flow then pass from the screen-
ing drum 7 into the contacting section 9 of the drum by
means of a transition 8 with integrated conveying screw.
In order to keep down heat losses and arhieve intensive
contacting of the materiall the contacting section 9 of
the drum has a smaller diameter than the fractioning
section 7 of the drum. For instance, the contacting
section ~ has a diameter of only about 1 m when of a
length of about 7 m. Due to the rotation of the druml an
intensive rubbing of the matPrial, and consequently a dry
cleaning-off of the material, is achieved in this section
9. This can be intensified by an angulax, preferably
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hexagonal, shaping of this drum section. The s~me effect
can also be accomplished with a round cross-section of
the drum by installing fins.
The fine-paxticled solid residual substances are
separated from the packing receptacle parts in the
following section 10 of the drum, again designed as a
screening drum, and collected in th~e container 13. The
cleaned packing receptacle parts pass via a metal dis-
charge 11 with integrated conveying screw into the
container 14, from where they can be passed on, if need
be, to a packing press.
To improve the cleaning action, cold air is
extracted from the filling hopper 3 and heated up by
means of the heat exchanger 16. This air, heated to a
temperature of from 80 to 120C, in this case accom-
plishes firstly an improvement in the flow of the liquid
residual substances and consequently a better cleaning in
the screening drum 7. A drying and complete outgassing of
the residual substances takes place in a second phase,
enabling attached matter to burst. In order to prevent
the hot air flowing past the contacting section 9, the
housing l is made in two parts. It is sealed off in each
case at the races of the drum bearings 17. Consequently,
an uncontrolled escape of emissions is prevented. For the
same reason, the collecting containers 12, 13 and 14,
which are charged from the screening drum sections 7 and
10 as well as $he metal discharge 11, are located inside
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the housing. The transitional section 8 with integrated
conveying screw is provided in order to achieve a very
small cross-section of the contacting section and con-
sequently a very effective utilization of the hot air
stream. To reduce the risk of explosion, with the aid of
a fan 20 an air stream is set in the working chamber 4 of
the size-reduction apparatus, the chute 6, the screening
drum wi~h li~uid fractionator 7, transition 8, con~acting
section 9, drum section 10 and metal discharge 11 via a
stack 18 and a waste gas line 19 in such a way that an
at least 8-fold air exchange/min is ensured in the
installation. The waste air is passed on to an
inci.neration installation. In addition, an active ex-
plosion suppression system 21 with pressure sensors and
powder extinguishing system is installed. The complete
housing 1 of the installation is provided on the upper
side with explosion flapæ 22. In addition, a shut-off
slide valve 23 is installed above the working chamber 4
of the size-reduction apparatus.
In cases of a high liquid content, a liquid-
binding medium, or example sawdust, may also be injected
by means of the device 24.
