Note: Descriptions are shown in the official language in which they were submitted.
-' ~2~S56
-- 3 --
Process for the operation of a system for the production
of a fibrous and a granular material
FIELD OF THE INVENTIO~
~he present invention concerns a process for the operation
of a system for the production of a fibrous and a granular
material from household, agricultural, forestry waste, or-
ganic waste of the manufacturing and/or service industri-
es.
BACKGROU~D OF THE I~VENTION
There are several known processes for the production of
fibrous and/or granular material from household, agricul-
tural and forestry waste, organic waste of the manufactu-
ring and/or service industries, but they all have the dis-
advantage that in the course of processing about 30
weight-~ of theoretically useful initial material i.s dis-
carded as useless waste; this not only involves a loss of
still useful material but also causes considerable cost
for the disposal of such material discarded as waste.
_ 4 _
A Swiss patent not published heretofore (SWi5S patent ap-
plication No. 9557/80-0) discloses a system for the pro-
auction of a fibrous and a granular material from house-
hold, agricultural, forestry waste, organic waste of the
manufacturing and/or service industries, cornprising an
opening unit to open the material to be processed, a frac-
tionating unit to obtain the fraction easy to reduce me-
chanically and the fraction difficult to reduce mechani-
cally; a first reducing unit to reduce the fraction diffi-
cult to reduce, a second reducing unit to reduce the frac-
tion easy to reduce, a drying unit to dry the different
fractions, and a further fractionating unit for the joint
re-fractionating of the re-united, dried fractions by par-
ticle size; and not having the said disadvantages of the
known systems, that is, not producing any secondary waste.
SUMMARY OF THE INVE~TIO~
It has been found that the operation of the system claimed
can be rendered substantially simpler and cheaper if accor-
ding to the present invention at least the drying unit of
the said system is heated by means of the fibrous material
produced by the system.
~ 20~5i56
..
This permits to dispense entirely with the hitherto neces-
sary use of fuel oil for the operation of the drying unit,
the delivery and storage of fuel oil. It offers the advan-
tage of considerable savings in the construction and in
the maintenance of such a plant~
The remainder of the fibrous material produced by the
system can, if aesired, be used direct to operate a dis-
trict heating system or a steam boiler, for example.
In this, it may be expedient to carbonize the fibrous ma~e-
rial for the heating of the drying unit.
It may be of advantagP to use the fibrous material in
loose condition for the heating of the drying unit.
It may further be expedient to use the fibrous makerial in
pressed condition, as in the form of bricks or pellets,
for the heating of the drying unit~
The invention is now to be illustrated by way of example
with reference to the accompanying drawing.
~2Q9~5~
DETAILED DESCRIPTION
As the drawing shows, t~e 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 ibrous crude material can
be given the structure desired, and that the important com-
ponents such as cellulose and lignin have 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 widely varying waste by cutting, chopping
and/or shredding to a size suitable for further proces-
sing. This function can be perormed by cutting or beating
mills and by choppers or shredders. To ensure trouble-free
processing and to obtain the required structure, fineness
2~ and purity of the final product, it is preferable to use a
slow-running cutting mill such as is commercially avail-
able in various versions. It is expedient to use a version
having multi-knie shafts arranged side by side and run-
12~95~6
-- 7 --
ning in opposition to each o~her. 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
S should be reversible. Such a machine is commercially avail-
able by t~e designation "shredder"~ Such or similar ma-
chines 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 to a conveyor unit consisting of a vibrating chu-
te 4.
To ensure trouble-free operation in the succedding stages,
it is important to remove completely any iron parts pre-
lS sent in the waste. For this purpose, the conveyor unit 4forwards the material in the form of an evenly aligned and
relatively thin flow layer past a magnetic 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.
D5~
-- 8 --
The magnetic band 5 serves to remove the iron parts pre-
sent in the upper por~ion of the flow layer. The rotating
drum magnet 6 serves to remove the iron part~ present in
the lower portion of the flow layer.
The magnetic 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 packet~s which may be passed on to
a scrap metal foundry.
The material thus cleared of iron parts passes to a frac-
tionating unit lO. The latter comprises a joggling screen
11 of about 6mm mesh 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 coar.se
lS 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 joggling screen ll as cannot, be-
cause of its si~e and/or weight, pass through the screen
or be sucked away therefrom, for the purpose of obtaining
2~ a low-reducibility fraction.
This separation into three fractions has the advantage
that the succeding reducing llnits 14 and 15 are relieved
~2~35~6
of the fine parts which do not exceed the required final
size. The quota of such ines i8 normally about 15
weight-%, which means that in the succeeding reducing sta-
ges about 15~ of energ~ is saved. The fines thus removed
are passed through a duct 16 bypassing the two reducing
units 14 and 15 and are then admixed to ~he waste reduced
in the latter two unitsO
The separation into the two coarse fractions has the ad-
vantage ~hat the two very different waste components are
separated and can therefore be reduced to the required fi-
nal size by reducing units best suited to each, and can in
addition be given ~he required material ~tructure, 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 ana mainly specifically heavy granular frac-
tions, a very high separation accuracy and purity is achie-
ved for the individual fractions.
The suction unit 12 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 sucksfrom 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
ss~
-- 10 --
for final struc$uring and reduction to a reducing unit of
the fine chopper type. Such reducing units are commercial-
ly available under such designations as fine choppers, cut-
ters or fine mills. It has been found expedient to use ro-
tor type reducing units in which knife rotors work againstknife 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 11
and the suction unit 1~ and which is of low reducibility
and in practice consists largely of inorganic matter, now
undergoes a reducing process in the separate reducing unit
14. This unit serves to reduce the different waste compo-
nents to t~e required final size of 6mm screen mesh suitab-
le for complete recycling. Such reducing units 14 are com-
mercially available by the designations of 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
il2~95~;6
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
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 heating 34 and through the re-
circulation duct 19, and the discharge of the moisture-
loaded air~ proceed continuously and are also controllab-
le, for the purpose of controlling to a target value the
residual moisture of the material leaving the drying un1t
18.
After the drying unit 18, ~he material thus treated is se-
parated by a separating unit 20 into a light and a heavy
fraction, and the light fraction then passes to a waste
air separator 21 of cyclone type for the discharge of the
damp waste air from the drying process. By this arrange-
ment it is possible considerably to reduce the wear in the
waste air separator 21 and at the same time considerably
increase the dependability thereof. The material leaving
the separator 21 is then re-united with the previously se-
parated light fraction, and passes through an ozone treat-
ment 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 particle
~Z~5~
- 12 -
,,
size of less than 3mm2, the second a particle size of bet-
ween 3 and 6 mm2, and the third a particle size of over
6mm2. The fractionating unit 23 may have oscillating or vi-
brating working surfaces. It is preferable to use a light-
weight version having a vibrating working surface. Amplitu-
de and vibration rate should be variable to permit intensi-
ty and residence time of the treatment to be regulated.
The three size fractions delivered ky the fractionating
unit 23, each composed of organic ~mainly light) 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 t~e organic substances.
Such air separators are commercially available in various
versions and are also used in the food, cattle feed and
wood industries.
The fine 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
is such ~hat the mainly organic light particles are entrai-
ned by the air flow, while the mainly inorganic specifi-
~2~556
. - 13 ~
cally heavy particles drop down against the air flow.
~he light particles thus entrained pass to a cyclone 27
which is arranged directly as a silo feed unit on the raw
material silo 28.
The specifically heavy particles dropping down against the
air flow are passed to the granulate silo 29.
The intermediate ~raction delivered by the fractionating
unit 23 passes for final fractionating to the air separa-
tor 25. The light particles separated there may be passed
to 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-
rators 24 and 25. ~he light particles separated by the air
separator 26 are l.ikewise delivered to either of the raw
material silos 28 and 31~ The mainly inorganic heavy gra-
nulate separated by the air separator 26 passes, mixed
wit~ the granulate from the air separators 24 and 25, into
~he granulate silo 29.
~Z~g5~6
The dust-loaded waste air from the air separators 24, ~5
and 26 and from the separators 27 and 30 passes to a fil-
ter unit 32. The dust separated in ~he latter, 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 final products, viz. three flat fibre
ractions and one dust fraction, in separate silos faci-
litates and extends the possibilities of re-use.
of cours~, the mainly inorganic heavy granulates from the
air separators 24, 25 and 26 may instead be stored as sepa-
rate lots.
The fibrous material thus obtained may, for example, be
processed further for the production of board or other
building materials or converted into heating fuel in the
form of bricks or pellets9 The granular material obtained
can also be used as fertilizer and soil improver and as
aggregate for asbestos, cement and brick products and for
artificial s.one, bituminous pavings 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 quota of non-combustible
~2~SS~;
- 15 -
substances in the specifically light fibrous fraction in
this process is equally high or lower than in the comparab-
le wood chip fractions which are still normally used in
pressed board production.
According to the present invention, the heating 34 of the
drying unit 18 is operated with fibrous material taken as
fuel from the raw material silos 28 and/or 31 through the
transportation duct 35, and for simplicity it is prefe-
rable to use the fibrous material for this purpose in the
loose condition as produced.
This arrangement complete]y obviates the necessity of
using fuel oil for the operation of the drying unit 18,
and this results in considerable savings in the operation
of the plant as compared with former practice.
