Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
The p:resent :i.nvention relates to a p:rocess for the
producl::ion of a .E:i.b:rous ancZ a gra~ .l.ar mat.e.r:ial f.rom house-
hold, agricu1Lural al~d forest.ry waste, organic wasLe o.E the
rnanu:Eacturirlg and/or service i,ndustri.es; a system for the
performance of such process; and a use o.E the fibrous and
the granular material produced by the sa,id process.
There are several known processes for -the produc-
tion of fibxous and/or granular material from household,
agricultural and forestry waste, organic waste of the manu-
fac-turing and/or service industries, but they all have the
disadvantage tha-t in the course of proeessincJ about 30
weight % of theoretically useful initial material is dis~
earded as useless waste; this not only involves a loss of
still useful rnaterial but also eauses considerable cos-ts for
the disposal of such material discarded as was-te.
The present i.nventi.on provides a proeess which
does not involve the disadvantages mentioned, that is, whieh
does not produee seeondary waste.
~7,~
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Acco.rdi.ng to the present inverltion there is pro-
v:icled a process in Wtl:i.CT`I ttle WaSte ~0 be prOCeC.~ ;ecl IlllderyO(eS
an openi.nc3 tr:eatment, the opened waste :i.s cl:iv;.ded .irl~o at
least two fractions, viz. (a) in~o a fraction easy ~o reduce
mechanically and (b) i.nto a fractjon di:Eficult to recluce
mechanically. These lwo fractions, separately from each
o-ther, are next reduced to the required final product par-
ticle size, then both fractions are dried to a specific
maxi.mum residual moisture content by heating and extraction
of the resultant steam, and sterilized, and both fractions,
reunited and, i.f applicable, after an intermediate trea~-
ment, are jointly divided again into at least -two fractions
by particle size. ~or this, it will be expedient if the
opened was-te is divided into at least
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~2~so~æ
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three fractions, viz. (a) into a fine fraction not excee-
ding the required :Einal product si~e, (b) into a coarse
fraction easy to reduce mechanically, and (c) in-to a coar-
se fraction difficult to reduce rnechanically; next, if the
two coarse fractions, separately from each other, are re-
duced to the required final product part.icle size, then if
all three fractions are dried to a specific maxirnum resi-
dual moisture content by heating and e~traction of the re-
sultant steam, and sterilized, and all three frac-tions, re-
united and, if applicable, after an intermediate treat-
ment, are jointly divided again into at least two frac-
tions by particle size.
Where the waste delivered contains magnetically removable
metallic components, it will be expedient to remove such
components after the opening of the waste to be processed
and before the division thereof into several fractions.
Where a ~Jaste gas separator i5 used, it will be expedient,
with a view to reducing the mechanical wear thereof by the
material passing through, if immediately after drying and
sterilization the material thus treated is divided into a
light and a heavy fraction, and if the light fraction is
passed to a waste gas separator for the purpose of remo-
ving the damp gas, in particular air, developed in the
drying stage, and then the light fraction, after removal
-- 5 --
of the damp waste gas, :i5 unite~d with the heavy fraction,
and the two fractions are jointly passed to the further
fractionating stage.
It has been found advantageous to divide the dried and ste-
rilized material into three fractions, one of which has a
particle si~e of less than 3mm2 screen mesh, the second a
particle sixe of 3 to 6mm2 screen mesh, and the third a
particle siæe of over 6mm2 screen mesh.
For many applications of the material produced it ~i]l fur-
ther be expedient if the ma-terial, dried and sterilized
and preferably, if applicable, after previous fractiona-
ting into at least two different particle si~e ranges, is
divided into at least two fractions by specific gravi-ty.
For thiæ, it is advantageous to divide the material into
at least three fractions by its speci*ic gravity, viZo (a)
into a light fraction consisting chiefly of organic fib-
res, (b) into a hea~y fraction consisting chiefly of inor-
ganic granulate, and (c) into a dust frac-tion consisting
chiefly of dust particles.
With a view to eliminating any o~fensive smells and any un-
desirable bacteria still present, it is expedient to ex
pose t~e dried and sterili~ed material to an ozone treat-
ment.
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It is another object of -t.he present invention to provide a
system for the performance of th~ process hereunder, cha-
racteri~ed in that it comprises an opening unit for the
opening of the material to be processed, a frac-tionating
unit for separation into the fraction easy to reduce me-
chanically and the fraction diEficult -to reduce mechani-
cally, a first reducing uni-t to reduce the fraction of low
reducibility, a second reducing unit to reduce the easily
reducible fraction, a drying unit to dry the different
fractions, and a further fractionating unit :Eor the joint
re-fractionating of the re-united dried fractions by par-
ticle size.
For this, it will be expedient if the said system compri
ses a fractionating unit with at least one joggling or os-
lS cillating screen to obtain a fine fraction; a suction unitclearing the top of the joggling or oscillating screen to
obtain the mechanically easily reducible coarse fraction;
and a receiving arrangement to receive such material pre-
sent on the joggling or oscillating screen as cannot, be~
cause of its size and/or weight, pass through the screen
or be sucked away, to obtain the low-reducibility frac-
tion and a first reducing unit to reduce the low-reducibi-
lity coarse fraction, and a second reducing unit to reduce
the easily reducible coarse fraction.
lt will be expedient iE the first reducing unit
corlsists of a hammer, :impact or beating rn:ill. Also, it will
be of aclvantage iE the second reducing un:il consisl:s o a
fine chopper, a cutter or a fine mill and presents at least
one knife rotor.
It will further be expedien-t if a conveyor consis-
ting of a conveyor belt or a vibrating chute is arranged
between the opening uni-t and the fractionatiny unit, and if,
for the removal of metallic components from the opened
material being conveyed, (a) a magnetic band is arrangect
above the said material and immediately above the conveyor,
and (b) a drum magne-t is arranged below the said material a-t
the end o~ the conveyor, over which drurn magnet lhe material
passes.
Finally, it is yet a further objec-t of the present
invention to use the fibrous material produced hereunder for
the production of pressings, such as pressed board, or
bricks or pellets serving as heating fuel.
X
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The invention .is n~ -to be illustra-ted by way of example
with reference to the accompanying drawing.
DETAILED DESCRIPTION
As the drawing shows, the waste is tipped into a bunker 1.
it is preferable to use waste which has undergone little
or no fermentation and which has not been subjected to any
treatment such as comminution, sorting, compaction on
dumps or chemical treatment. The use of fresh organic wa-
ste has the advantage that the fibrous crude material can
be given the structure desired, and that the important com-
ponents such as cellulose and lignin ha~e been neither re--
moved nor destroyed.
The waste thus bunkered is passed continuously or discon--
tinuously by a mechanical conveyor 2 to an opening unit 3.
This unit serves to open the crude material, which is pre-
sent in various forms, into its loose components, and also
to reduce the ~idely varying waste by cutting, chopping
and/or-shreading to a size suitable for further proces-
sing. This function can be performed by cutting or beating
mills and by choppers or shredders. To ensure trouble-free
processing and to obtain the required structure, fineness
and purity of the final product, it is preferable to use a
slo~t-running cutting mill such as is commercially avail-
æ
_ 9 _
able in various versions. It is expedient to use a version
having multi-knife shafts arranged side by side and run-
ning in opposition to each other. Also, the multi-knife
shafts should generally run at low speeds, and the indivi-
dual shafts should run at different speeds. Again, for de-
pendability, performance and self-cleaning, all shafts
should be reversible. Such a machine is commercially avail-
able by the desîgnation "shredder". Such or similar machi-
nes are also used for the destruction of old cars and
other sheet-metal products.
The material thus opened by the opening unit 3 and reduced
to a size corresponding to a screen mesh of 20 ~ 30 cm
drops on ~o a conveyor unit consisting of a vibrating chu-
te 4.
~VC~ ee~
To ensure trouble-free operation in the_~uq~ddi~g stages,
it is important to remove completely any iron parts pre-
sent in the waste. For this purpose, the conveyor unit 4
forwards the material in the form of an evenly aligned and
relatively thin flow layer past a maynetic band 5 arranged
above the conveyor unit 4 and delivers it at its end on to
a rotating drum magnet 6 arranged below the conveyor unit.
As the waste quantities leaving the opening unit vary, the
conveyor unit 4 is provided at a point before the magnetic
band 5 with an equalizing unit, not shown.
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The magnetic band 5 serves to rernove -the iron par-ts pre-
sent in the upper portion of the 10w layer. The rotating
drum magnet 6 serves to rernove the iron parts present in
the lower portion of the flow layer.
The maynetic units 5 and 6 are connected by a conveyor
unit 7 to a bunker 8. From the bunker 8, the metal removed
passes into a press 9 which presses the metal parts into
commercially acceptable packets which may be passed on to
a scrap metal foundry.
The material thus cleared of iron parts passes to a frac-
tionating unit lOo The latter comprises a joggling screen
ll of about 6mm mes'n to obtain a fine fraction. It further
comprises a suction unit clearing the top of the joggling
screen ll to obtain a mechanically easily reducible coarse
fraction, and is provided at the lower end of the inclined
joggling screen ll with a chute 13 to receive such mate-
rial still present on the ]oggling screen ll as cannot, be-
cause of its size and/or weight-,~pass through the screen
or be sucked away therefrom, for the purpose of obtaining
a low-reducibility fraction.
This separation into three fractions has the advantage
that the succeding reducing units 14 and 15 are relieved
of the fine parts which do not e~ceed the required final
1~iO62
size. The quota of such fines is norrnally abou'c 15
weight-~, which rneans that :in the succeed:ing redllci.ny sta-
ges about 15% of energy is saved. nle fines thus removedare passed through a duct 16 ~ypassing the two reducing
units 14 and 15 and are then admixed to the waste reduced
in the latter two units.
The separation into the two coarse fractions has the ad-
vantage that the two very different was-te components are
separated and can therefore be reduced to the required fi-
nal size by reducing units best suited to each, and can inaddition be given the required ma-terial structure, so that
in the last stage of the process, in which the material is
sorted first by size and then into mainly specifically
light fibrous and mainly specifically heavy granular frac-
tions, a very high separation accuracy and purity is achie-
ved for the individual fractionsO
The suction unit 1~ may be a commercially available unit
such as is used in the chipboard and cattle feed indu
stries. The light material which the suction unit 12 sucks
from the waste flow through the suction ducts 12a, 12b and
12c consists chiefly of paper, cardboard, foil, textiles
and wood chips; that is, organic materials~ and is passed
for final structuring and reduction to a reducing unit of
the fine chopper type. Such reducing units are commercial-
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ly available unaer such designation~ as fine choppers, cut-
ters or *ine mills. It has been found expedient to use L-O-
~or-type reducing ~nits in which knife rotors work against
knife stators, or knife rotors against knife rotors, and
which present a barrier-type selector to obtain -the requi-
red final material size.
The coarse fraction, which has been cleared of fines and
of specifically light components by the joggling screen ll
and the suction unit 12 and which is of low reducibili-ty
and in practice consists largely of inorganic matter, now
undergoes a reducing process in the separa-te reducing unit
14. This unit serves to reduce the different waste compo-
nents to the required ~inal size of 6mm screen mesh suitab-
le for complete recycling. Such reducing units 14 are com-
mercially available-by the designations o~ hammer, impact
or beating mills, and can be used if provided with a bar-
rier-type selector set to the smallest screen mesh~
The fractions from the reducing units 14 and 15 and from
the bypase duct pass jointly into a bin 17. The material
stored in the latter then passes to a drying and steri-
lizing unit 18. This unit serves to dry the material to a
specific constant residual moisture and to destroy nocuous
substances present in the material, such as pathogenic
bacteria. For the purpose, temperatures of over 100C are
~$~
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attainable in the drying unit 18, and the residence time
of the material in the unit is also controllable. the supp-
ly of hot dry air from the heatingi\34 and through the re-
circulation duct 19, and the discharge of the moisture-
loaded air, proceed contlnuously and are also controllab-
le, for the purpose of controlling to a target value the
residual moisture of the material leaving the drying unit
1~3 .
After the drying unit 18, the material is separated by a
separating unit 20 into a light and a heavy frac~ion, and
the light fraction then passes to a waste air s~parator 21
of cyclone type for the discharge of the damp waste air
from the drying process. By this arrangement it is possib-
le considerably to reduce the wear in the waste air separa-
tor 21 and at the same time considerably increase -the de-
pendability thereof. The material leaving the separator 21
is then re-united with the previously separated light frac-
tion, and passes through an ozone treatment unit 22 to a
fractionating unit 23. The-latter serves to separate the
dried and sterilized material by particle size into three
fractions, one of which has a particl~ size of less than
3mm2, the second a particle size of between 3 and 6 mm2,
and the third a particle size of over 6mm2. The fractiona-
ting unit 23 may have oscillating or vibrating working sur-
faces. It is preferable to use a lightweight versionhaving a vibrating working surface. Amplitude and vibra-
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t.ion rate should be ~ariab]e to permit. intensity and resi-
dence time of the treatment to be regulatedO
The three size fractions delivered by the fractionating
unit 23, each composed of organic (mainly liyht) and inor-
ganic (mainly heavy) particles, pass by separate paths tothe final fractionating stage. Final fractionating is per-
formed by the air separators 24, 25 and 26, which serve to
separate the mixed materials such as minerals, nonferrous
metals, hard plastics, etc., from the organic substances.
Such air separators are commercially available in various
versions and are also used in the food, cattle feed and
wood industries.
The .Eine fraction delivered by the fractionating unit 23
is forwarded pneumatically for final. fractionating to the
air separator 24, where the material is fed at a certain
point into an opposed air flow. The rate of the air flow
i.s such that the mainly organic light particles are entrai-
ned by the air flow, while the mainly inorganic specifi-
cally heavy particles drop down against t~e air flow.
The light particles thus entrained pass to a cyclone 27
which is arranged directly as a silo feed unit on the raw
material silo 28.
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The specifieally heavy par-ticles droppiny down against the
air flow are passed to the granu]ate s.ilo 29.
The intermediate fraction delivered by the frac-tionating
unit 23 passes for final fractionating to the air separa-
tor 25. The light particles separated there may be passedto either of the separators 27 and 30 of the silos 28 and
31. The mainly inorganic heavy granulates separated by the
air separator 25 pass to the granulate silo 29 mentioned.
The coarse fraction leaving the fractionating unit 23
passes for final fractionating to the air separator 26,
which works in the same manner as the two other air sepa-
ratoxs 24 and 25. The light particles separated by the air
separator 26 are likewise delivered to either of the raw
material silos 28 and 31. The mainly inorganic heavy gra
nulate separated by ~he ~ir separator 26 passes, ~ixed
with the granulate from the air separators 24 and 25, into
the granulate silo 29~
The dust-loaded waste air from the air separators 24, 25
and 26 and from the separators 27 and 30 passes to a fil-
ter unit 32. The dust separated in the la-t-ter, consisting
chiefly of organic fines, can be passed to the dust silo
33 or to the silos 28 and/or 31, as preferred.
The storage of the fina:L products, ViY.. three :Elat
:Eibre fracti.ons and one dust Eracti.on, :i.n seL)a:rate silos
faci:Litates and extends the possib:i:Li.ties of .reuse.
Of course, the ma:inly inorganic heavy granulates
from the air separators 24, 25 and 26 may instead be stored
as separate lots.
The fibrous material thus obtained may, for
example, be processed further fo.r the production of board or
other building materials or converted into hea-ting fuel in
the form of bricks or pellets. The yranular material ob-
tained can also be used as fertlli.zer and soil improver and
as aggregate for asbestos, cemènt and brick products and for
.5 artificial stone, bituminous pavi.ngs and concrete.
As may be seen from the embodiment described, -the
entire waste delivered, including the magnetically removed
metal, is recycled in -this process. The quote of non-
combustible substances in the specifi.cally light :Eibrous
fraction in this process is equally high or lower than in
the compaLable wood chip fractions which are still normally
used in pressed board production.
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