Note: Descriptions are shown in the official language in which they were submitted.
1059964
The present invention relates to a process and an
apparatus for recuperating the light fraction of solid urban
waste comprised principally of paper, cardboard, plastic and
textile fibres, by means of a pneumatic system.
The current shortage and foreseeable scarcity of raw
materials and energy make it necessary to attempt to re-use,
wherever possible, all or part of the components of any type
of waste produced by urban centres and industries.
These recuperated and classified components can be
put to further use, either for recycling to their original state
or for a secondary use.
Respective of solid urban waste and in accordanc~ with
known analyses of composition, it is observed that an important
fraction thereof, which we can call the light fraction, is
comprised of paper, cardboard, plastic and textile fibres.
Separated from the remaining components (metals, glass, ferment-
able organic matter and others), this fraction would represent
an important source of raw material if it were used to manufac-
ture paper pulp, or a possible energy source if used as fuel, or
it could have other secondary uses such as, for example,
transformation into building materials.
The present invention relates to a mechanical ripping
or tearing process which, in combination with a pneumatic
collection and conveyor system, permits recuperation of a high
percentage of this light fraction.
As this is a completely new field the known devices of
this type are very few. Some vertical backward flow pneumatic
graders are known and also manual sorting-belts, which form part
of some plants for transforming waste into organic fertiliser.
The process of this invention permits recuperation of
a high percentage of this light fraction with the least amount
of manual labour, since the extraction can be entirely automatic.
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At the same time, considering its orlgin the product obtained
can be of high quality, inasmuch as the impurities lt contains,
proceeding from the substances ~or which this light fraction has
generally served as packaging, can be regarded as minimal.
The product obtained, that is, the light fraction com-
prised of paper, cardboard, plastic and textile fibres, will re-
quire subsequent processes of transformation, but it already has
direct intrinsic commercial value. Solid urban waste is generally
collected in paper or plastic bags, and these bags hold the com-
ponents in which we are interested. In other instances where
waste is collected in centralised containers, all its components
are mixed together very heterogeneously.
The first part of the system of the invention consists
of an apparatus which tears open the containers and frees the
waste, which can then be sorted.
Since the object is to recuperate the light fraction,
the second part of the system of this invention consists of
pneumatic separation which breaks the initial product down into
two fractions: one light and the other heavy.
To carry out this process use is made, as the first
device of the invention, of a mill we will call the ripper. This
consists of a housing containing two shafts which rotate in
opposite directions and to which some link chains are perpendi-
cularly joined. The characteristics of the latter are determined
by the capacity of the installation. The gap between the shafts
may be controlled by any adequate system.
When the waste passes among the chains being whirled at
a certain speed, its components are ripped apart, only the fragile
components (glass, pottery and the like) being crushed. Simul-
3~ taneously, the whirling of the chains creates the effect of a
direct-drive fan aimed at the lateral exit of the mill. Extrac-
- tion is made from the lower part of the mill by a conveyor belt
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105996~
which is protected from the elements propelled by the chains
by a shelf consisting of two inclined planes. In this
manner the heavy fraction is extracted from the mill by the
conveyor belt, and the light fraction is extracted by the flow
of air produced by the whirling chains, similar to a pneumatic
conveying system.
According to a broad aspect of the present invention,
there is provided an installation for separating a hetero-
geneous substance into a light fraction and a heavy fraction,
particularly for the treatment of solid urban waste. The
installation comprises a chain mill formed by an open-buttomed
housing containing rotatable chains for ripping and tearing
materials fed into the mill. The chains are arranged to
produce on rotation a flow of air which passes into an open-
bottomed collection hood. A conveyor belt is disposed beneath
the mill and the hood and the upper run of which is movable
in a direction from the chain mill to the collection hood.
A settling cyclone is connected to an exit located in the
upper part of the hood, and a dust collector is connected to
the cyclone.
According to a further broad aspect of the present
invention, there is provided a process of separating light
and heavy fractions from a heterogeneous substance. The
process comprises the steps of introducing the substance into
a chain mill where the substance is subjected to the action
of rotating chains. The substance is expelled from the chain
mill partly by the action of the chains, partly by an airflow
generated in part by the action of the chains, and partly by
a conveyor. The expelled parts are subjected to pneumatic
suction generated by a dust collector so that the light
fraction is drawn into a settling cyclone for collection.
The remaining heavy fraction are drawn out through an exit
opening on the conveyor.
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~OS9964
The invention will be better understood by an
examination of the following description together with the
accompanying drawing which illustrates a manner of arranging
the elements constituting the system of the invention.
Numeral 1 in the figure represents the ripper mill
housing, 2 is the feed hopper, 3 are the two shafts with their
chains attached, 4 is the protecting shelf, 5 is a conveyor
belt; 6 is the mill assembly with the collection hood, 7 and
8 are adjustable openings in the lateral ramps of the hood,
9 is a deflector and 10 is an exit for material not collected
by the hood, arrow 11 indicates the flow of air aspirated by
the settling cyclone 14, arrow 12 indicates the flow produced
by the mill, and arrow 13 illustrates the flow entering
through the mentioned exit 10.
Both the settling cyclone 14 and the dust collector
15 are conventional apparatus.
The second device is situated at the lateral exit
of the mill (first device), which second device consists of
a pneumatic collection hood connected to the settling cyclone
14, the suction or draft of which is furnished by a dust
collector 15. The light material, collected in the lower
part of the cyclone 14 is extracted by a compactor or other
system. The collection hood forms part of the second device
which completes the system. Its design must meet the
following requisites:
- The assembly 6 with the mill must be hermetic, and
sufficiently large to permit passage of the bulkier objects.
- Air intakes regulated by means of sliding plates are located
on the lateral ramps 7 and 8 of the collection hood, and permit
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1059964
proper flow control according to the characteristics of the
material treated,
- A deflector 9 inside the collection hood, adjustable as to
length and inclination, divides the hood into two sections: the
direct collection chamber and the declassified material recuper-
ation chamber,
- ~he hood exit 10 has a device for size adjustment according
to the products treated and the operation of the recuperati~on
chamber.
The phenomena achieved with this hood are the following:
The flow of air 11 sucked by the cyclone 14 is the sum
of flow 12 produced by the mill and which bears part of the light
fraction, plus the backward flow 13 entering the hood through
its lateral exit 10 and recuperating that part of the light
fraction tending to escape,
The air flows entering and leaving the hood may be regu-
lated with the valves located in the dust collector 15, in the
settling cyclone 14 and in the hood itself, Said valves are
interrelated, from the view point of the final resulting effect,
Adjustment of the adjustable collection elements in the
process will depend on the characteristics of the products
treated, on the desired yield and on the quality of the light
fractions it is desired to obtain,
The system of this invention is industrially applicable
in installations for treating solid urban waste to mechanize
separation of the light fraction,
The system or part of it may also be used for the pneu-
matic separation of a combination of light and heavy fractions
in any other industrial sector,
