CA1105913A

CA1105913A - Installation for the recovery of materials that are present in the solid city wastes for their subsequent utilization and/or their transformation

Info

Publication number: CA1105913A
Application number: CA276,020A
Authority: CA
Inventors: Manlio Cerroni
Original assignee: Rutir Srl
Current assignee: Rutir Srl
Priority date: 1976-04-09
Filing date: 1977-04-07
Publication date: 1981-07-28
Also published as: CS212790B2; IE45726L; NZ182439A; IT1057507B; IE45726B1; AU1910476A; SE7704125L

Abstract

ABSTRACT OF THE DISCLOSURE
Installation for the recovery of materials that are present in the solid city wastes for their subsequent utilization and/or their transformation, in which the plant is realized in such a way that the material is subsequently treated, without any manual operation, in a wholly automatic way, being foreseen sieves, discharges, conveyors, separators, etc. for the carrying out of the different treatment phases of the original material.

Description

5~13 1 It is well known that the solid city wastes contain many materials, that everyday are thrown away, and that viceversa could be used again in many other ways, also different from the original ones.
It is in fact well known that in the said wastes are present, for instance, notable amounts of paper coming out from all the wrappings and packages of the consumption goods, as also ferrous packages, as boxes, in which are preserved foods and other materials, and furthermore organic elements, as,. for instance, the kitchen wastes as vegetables, fruits, bread, etc. Furthermore, in these city wastes are present in a large amount plastics wastes comimg out in most cases, from the plastics packaging and more in particular form the film.
used for.the delivery and the transport of the different goods as also for the bags foreseen for the different discarded materials.
It is also useful have in mind that in these wastes is present also a noteworthy amount of glasses, especially as bottles, in connection with the diffusion of the use of non-20 returnable bottles. All these glasses with all the otheraforementioned goods, as also with other products, that are present usually and/or exceptionally in the solid city wastes, are worth of being recovered and used again.
In the past years were realized many different installations for the recovery of the solid city wastes, but these installations indeed had the purpose of using only the organic elements in the city wastes for obtaining a product, usually called "compost", being this material a kind of fertilizer, at the same time a corrective of the soil.

9 ~ 3~ r 1 At present, however this technology is undoubtly inadequate, as, a consequence of the demographic increase as also for the changed tenor of life of the residents, in the city wastes are present materials completely different from the ones of the past, not only from a qualitative point of view, but also as percent.
Indeed the presence of paper, plastic materials, glasses and metals - more in particular iron - is increased with a consequent reduction of the percent of the organic 10 materials.
Therefore it is evident that it is not more useful employ the previous te~hnology as the installations of the previous technology would meet big problems in connection with the percents of the obtainable product in connection with the amount of the materials to be rejected, or discharged and also because the well known "compost" is now finding heavy trade problems as consequence of the introduction on the markets of new kinds of fertilizers.
It is therefore an object of the present invention an 20 installation, in which is possible pick-out automatically papers, plastic materials, glasses, metals - more in particular iron -organic materials, etc. r from the heterogeneous mass of the wastes and in which the separated wastes can be sent to single stations, where the raw selected materials are improved in such a way to can be, in a second time, be transformed in new products that are requested firmly and with increasing interest.
The installation of the present invention has sub-stantially the purpose of linking together the working of different machines in such a way to make easier the securing of products 30 of particular interest and, at the same time, with an unchanging ;3 1 and disadvantagefree working of the said machines.
The installation, according to the present invention is set up on the automatic separating of the different components of the wastes mass reaching in the selected materials also the 85~ of the wished material.
Therefore, the installation is working following a sequence of phases, that are carried out in stations that can be deemed as satellite plants, where are carried out the different operations of purification and transformation of the different materials in such a way to allow their trade and - eventually their preservation for the use in a second time.
The installation, according to the present invention, works following a sequence of actions, that can be summarised as follows:
1. Breakage of the containers of the solid city wastes, i.e. in the majority of cases of the plastics bags in which are collected the solid city wastes, to obtain such wastes in bulk, in such a way to allow the following working phases;
20 2. Rejection of the coarse materials, that are sent to the dump or at the incineration plant;
3. Boards separation;
4. Separation of the paper mixed with plastics film;
5. Dry separation of plastics films from the paper;
6. Separation of the organic materials in their raw state for subsequent use;
7. Use of the best portion of the organic materials recovered in the phase ~ for the production of stockfeed;

5~3~

1 8. Use of the remaining portion of the organic wastes, obtained in the phase 6, after the removal of its best elements according to the phase 7, for the manufacture of dry-fertilizer;
9. Separation in all the phases of the treatment of the iron materials for their subsequent use;
10. Separation of the glasses, preferably downstream the phase 7, i.e. downstream the plant for the production of the already quoted stockfeeding.
The attached drawing shows, using a block diagram, the plant, according to the present invention, with its satellite plants for the carrying out of the different working cycles.
With reference to the said drawing, the wastes, that in a first moment are discharged in a dump 1 are drawn up by a polyp and by an overhead travelling crane 2 and loaded on feeding conveyors. On these conveyors the wastes are leveled by a leveler 3 for metering the amount of the wastes, whereas, of course, a convenient device 4 provides to the cutting and the opening of the bags, in which are the wastes. A first sieve 5 at the end of these conveyors allows the separation of the more coarse parts. These more coarse parts are the ones that are greater of a pre-established size and usually are comprising great board boxes and/or bodies - as for instance mattresses, chairs, prams, etc. - that cannot be regarded as regular solid city wastes.
The said bodies of great sizes, that cannot be recycled are sent to the discharge, or to the incineration plant, whereas the boards, or similar materials, that are rejected by the sieve 5, are sent to a machine 6, realized in connection with the idea used in the design and realization 1 of the machine for the tearing of the bags, quoted as the one used in the phase 4. On this machine, the board boxes are broken, cut, torn, pulled away letting unchanged the materials -usually metallic ones - that are within the said boxes. The so treated material coming out from the machine 6 is sent, through a conveyor to a separation electromagnet 9, that provides to the recovery of the magnetic materials.
The non-magnetic material coming out from the separator 9 is fed to an oscillating feeder conveyor 10 feeding, at its turn, an air classifier under vacuum, where air streams provide to separate the most light materials, as for instance paper elements, from the remaining material. These light elements are carried in the decanter 11 of the machine and by a system of conveyors to the press 13.
The material that was not removed by the air streams in the air classifier 11, as too heavy, is fed to the incinera-tion plant or to other installations for a subsequent treatment.
Coming back now to the material passed by the sieve 5, the material is sieved a second time in the sieve 14, where the said material is divided in two parts, i.e. in a finally accepted part and a rejected one.
This material rejected by the sieve 14 is comprising, in prominent amount, papers, plastics films, plastics materials in other forms, hides, shoes and also some organic materials;
whereas, the accepted portion is comprising about exclusively mould and organic materials.
Of course, the amounts of the different materials obtained in these sieving operations is in connection with the nature of the raw waste materials.

1 At its turn, the materials that were rejected ~y the sieve 14, are conveyed, through the conveyor 15, under an electromagnetic separator 15, which is doing the same work of the already quoted separator 9. The remaining material now free of magnetic parts, and more in particular of iron, is conveyed to the oscillating conveyor 17 feeding another air classifier 18.
This air classifier 18 divides the coming material in a first portion comprising films and paper, that is fed to the decanter 18 of the said machine, whereas the heavy, undergoes the same destination of the one coming out the air classifier 11.
The material accepted by the classifier 18 comprises substantially paper and plastics films and it is a very interesting material, that must be subjected to subsequently treatment for obtaining usable materials.
To this purpose however is needed, before all separate the paper from the plastics films.
Such a separation is carried out in the station 19, where a machine, comprising substantially a toothed rotor, that-drawing advantage of the different elongation of the paper and the plastics films, before their breaking - works in such a way to break the paper, allowing the passage of the plastics films in unchanged sizes through the machine. After this passage through the machine of the station 19, it is still present a material comprising paper and plastic films, however, the paper has little sizes, whereas the plastics films have still great sizes.
A sieve 20, eventually a rotating one, provides to the separation of the two materials, accepting the paper and rejecting the plastics materials.

1 The rejected portion, comprising plastics materials can be immediately baled in the station 21 and sold, or can be fed to another section of the plant for its improvement through washing processes, regeneration, etc.
At its turn, the accepted part of the material, i.e. paper containng still some percent of plastics films, is baled in the station 22 from which is sent to another plant for being utilized for the production of paper pulp. Of course, the aforementioned baling in the station 22 is only an inter-mediate phase, not indispensable, for obtaining a long betweenthe waste working plant and the paper production plant.
Indeed, this paper comimg out from the station 22, comprising still some extraneous materials and conveniently baled, is sent through a feeder 23 to the hydropulper 24, where with the usual addition of water is, as usual, let soak. Of course, during this classic process, the real elements, are dispersed and de-fibred, whereas the contaminating, i.e.
extraneous, materials remain unchanged, with consequent very clear physical differences, easing the separation of these last materials from the paper pulp.
Indeed, these extraneous bodies must be separated from the paper pulp and such a separation must be a continuous one as the feeding is continuous.
It must be now pointed out that the usual hydropulpers are fitted with systems for the separation from the paper materials of extraneous light bodies in low percents, but they are not suitable for the treatment of the paper materials recovered from the solid city wastes as these paper materials are comprising a much higher percent of extraneous materials.

Therefore, the paper plant, according to the present invention, is equipped with a separator with a rotating sieve, or any ~59~;3 1 other suitable device which is connected with a usual hydro-pulper, through a valve that it is opened and closed periodically. This valve having the purpose of allowing the periodical elimination from the pulping apparatus of the paper pulp and of all the other materials, that cannot be pulped by the water.
Therefore, the original paper material comprising extraneous materials is sent in the practice to the afore-mentioned selecting device, i.e. the rotating sieve in such a 10 way to separate the watery paper pulp from the other materials as above quoted, that cannot be changed by the water action, having specific weight very variable, as the sieve 25 is working only in connection with the granulometry of the matter and not in connection with its density or other characteristics.
As in the case of all other sieves already quoted in this specification, the sieve 25 is rejecting as already stated, a portion of the material, comprising the polluting extraneous bodies, that can be sent to the incineration plant or to the discharge, whereas is feeding the accepted liquid material 20 comprising the paper fibres, i.e. the paper pulp to a collecting vat 26 from which is carried to the subsequent phases of depuration and thickening - the thickneing phase is carried out in a prethickener 27 and in a dehydrating press 28. t Having in mind that the paper is recovered from city wastes a very important treatment is the one subsequent the press dehydration of the mass, i.e. the sanitary treatment of the thickened pulp, that is carried out in a continuous autoclave 29~ which is not under pressure, where the material is kept at a sufficient high temperature, using steam, for 30 variable times, but always having a length of some tens of -- 8 ~

1 minutes, in such a way to grant the destruction of all the dangerous germs and of the bacterial flora, that can be present in the paper pulp.
Coming now back to the sieve 14, in which the accepted material is comprising in prominent amount organic material in connection with the way following which the material is accepted it is differently recovered.
A particular employment is the use of all the accepted material for the production of "compost" or dry fertilizer. Whereas another possible employment is to feed the accepted material to a separating sieve 30 in which the mould -the accepted portion of the material - is sent to the incinera-tion plant, or to the discharge, whereas the rejected portion, that is the more coarse, but at the same time, the more noble portion of this material can be used as stockfeed.
For obtaining the said stockfeed the rejected material of the sieve 30 is subjected to a sequence of treatments, i.e.
a washing a decantation, a pressing, a steriliZation, a drying, a depuration proceeds and at the end are subjected to pelletiz-ing and to the packing. In other words the rejected organicmaterial coming from the sieve 30 are fed to a washing sieve 31 where the material is subjected to an effective and strong wash for removing mould and inert elements, from this sieve 31 the material is carried to a suspension vat 32, where the inert waste, the heavy ones, as glasses, stones, iron pieces and different tailings, are falling on the bottom of the bat rom which they are discharged, from time to time, through a discharge mouth. From this decantation vat the light edible materials, comprising nevertheless always some extraneous materials, are carried out by two water streams, one ascensional and the other horizontal in the impact direction with the 5~

1 water coming out from the recovery water of the overfall of the decantation vat 32, in such a way to carry immediately to the elements having a specific weight than the one of the water.
From the overfall of the vat 32, the water and the edible materials are failing in the sieve 23, that has the purpose of separating the water from the edible materials. The said water is collected in tanks and recycled, whereas the material is going to the press 34, having the purpose of further reducing the amount of the water present in this treatment phase in the tO edible materials" At the end of this preparatory cycle, the organic material now deprived of the greatest portion of its heavy inert materials and of the water is sent to a sterilizing phase, in the sterilizers 35, that are autoclaves for a batch treatment of the material, in which this last one remains for the established time at the pre-established temperature.
Following this sterilization treatment, the product is dryed in the dryer 36, in which the moisture of the product is reduced at about 10% during this treatment, the size of all the organic materials is reduced, whereas the inorganic materials remain unchanged.
It is therefore possible, using another sieve 37 to separate the organic materials from the tailings of inorganic materials.
Indeed these polluting inorganic materials can be present in two general forms, i.e. a heavy portion comprising still glass, stones, that can be still present also in a very little amount and a light portion, i.e. papers, plastics, etc.
that have reached a greater volume. Therefore the more light portions are separated following one way and the heavy ones following another system. More precisely the light portions ~S`~!3~3 1 are separated through a rotating and vibrating sieve 37 and are sent to the incineration or to the discharge. At its turn, the accepted portion of this sieve 37 comprising still the heavy materials as little pieces of glass, or stones, that are escaped to the hydraulic separation in the vat 32 are separated through an air classification in the classifier 38, that allow the separation of the light and heavy materials, i.e., the air stream rising up removes the light portions comprising the organic materials, whereas last fall the heavy portion that are consequently discharged.
The so separated light portion is a stockfeed always in a coarse form, that is subjected to a milling in the mill 39, through this milling is obtained the pulverization of the said stockfeed, that is subsequently sent the stocking 40 and at the end to the pelletizing press for its transformations in pellets 41 as wished.
The iron portions collected by the different elec-tromagnets are conveyed to a rotating furnace for the elimina-tion of the polluting materials, that are comprising, as known, labels, paints, tin, etc. In this furnace all the said pollut-ing materials are destroyed and the resulting ashes are separated from the iron material in the sieve 43. The iron material is therefore sent to the press 44, that press this material in a bale ready for the transport and the subsequent selling.
The plant, according to the present invention, was of course, shown and described only by way of example, being evident that the different treatment phases can be subject to modifications, whether increasing or descreasing the same, in connection with the material at disposal for the treatment, having in mind that the solid city wastes have characteristics that, usually, are different in the different areas, but that, substantially are constant.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method for the recovery of materials that are present in the solid city wastes for their subsequent utilization and/or their transformation, in which the material is treated, without any manual operation, in a wholly automatic way, including the following steps:
a) tearing of the bags or the containers of the wastes for having the said wastes in bulk;
b) rejection of the coarse materials that are sent to the dump or to the incineration plant for the production of steam needed in the plant;
c) board separation;
d) separation of paper mixed with plastics films;
e) dry separation of the plastics films from the paper;
f) separation of the organic materials in their raw state for subsequent use;
g) use of the organic materials separated by step f) for the production of stockfeeding and/or the use as fertilizer;
h) separation of the iron parts in the different stations;
i) separation of the glasses downstream the plant for the production of the stockfeeding.

2. The method for recovery of materials as claimed in claim 1 including the sterilization treatment of the paper separated by step e) of claim 1 and of the organic material separated by step f) of claim 1.

3. The method for recovery of materials as claimed in claim 1 including the step of producing paper pulp obtained

Claim 3 continued .....

through the use of hydropulpers and a rotating sieve, in such a way that the materials which cannot pass through the rotating sieve are carried away continuously, whereas the materials which can pass through the rotating sieve are treated and sterilized in such a way to produce paper pulp.

4. The method for recovery of materials as claimed in claim 3 in which the hydropulper is provided with a valve which may be operated for opening and closing in a periodical manner as well as in a non periodical manner whereby the materials that are not sensitive to water action and cannot pass through the rotating sieve may exit from the hydropulper through the valve.

5. The method for recovery of materials as claimed in claim 4 in which the rotating sieve allows materials having a granular size smaller than a specific granular size to pass through the rotating sieve so that the materials which pass through the rotating sieve include paper pulp, which materials are subsequently thickened and then sanitized by a sterilization treatment carried out in containers maintained at elevated temperature using steam for a time suitable for obtaining sterilization.

6. The method for recovery of materials as claimed in claim 5 in which the sterilization treatment is carried out in containers which are not pressurized.

7. The method of claim 1 including the step of passing the organic materials separated by step f) of claim 1 through a sieve so that the larger particles of the separated organic materials which are more suitable for use in manufacture of feed stock do not pass through the sieve and are separated by the sieve from smaller particles of the separated organic materials.

8. The method for recovery of materials as claimed in claim 1 in which the portion that must be used for the manufac-ture of stockfeed are subjected to washing operations, being this washing process carried out through the passage in a suspension vat and subsequent forwarding to the separation; the separation sieve being feeded by the water coming from the overfall of the decantation vat and the water going to the separating sieve as a tangential stream and a rising up stream in such a way to help the separation of the materials having a specific weight greater than the one of the water.

9. The method for recovery of materials as claimed in claim 8 in which the water coming from the washing phases is recycled, whereas the materials are subsequently fed to the presses, the materials to be transformed in stockfeed being before to be real stockfeed subjected to a sterilization process and subsequent milling, in such a way that as consequence of the sterilization phase the organic materials have been subjected to a dischargen whereas the inorganic materials have not been sub-jected to the said shrinkage allowing therefore their granulo-metric separation.

10. The method for recovery of materials as claimed in claim 9 in which the heavy material are separated through air-classification and in which subsequently the so prepared stock-feed is let go through plants for the elimination of eventually remained glasses and after through plants for their pulverization and to the pelletizing presses for their transformation in pellets.