Method of processing refuse for conversion into shaped bodies

Abstract

Household, agricultural and forestry refuse is processed by subjecting it to aerobic decomposition in order to liberate its fiber content, whereupon the resulting product is sterilized, has its moisture content adjusted to a predetermined range and is converted into a mass of substantially dry, heterogeneous fiber-containing matter. This mass is then segregated into a plurality of different-size fractions with the coarsest fractions being separated from the remaining fractions which are admixed with a binder and shaped and hardened.

Parent Case Text

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation-in-part of my copending application, Ser. No. 7,996 filed on Feb. 2, 1970, and now abandoned.

Description

BACKGROUND OF THE INVENTION

The present invention relates generally to the processing of refuse, and in particular to the method of carrying out such process.

Still more particularly, the invention relates to a method of processing household, agricultural, and forestry refuse, individually or in various combinations.

It is hardly necessary to point to the ever-increasing accumulation of refuse. The problem of refuse disposal is taking on more and more importance on a world-wide basis, requiring constantly increasing expenditures for the collection and disposal of the rising quantity of refuse generated everywhere. The problems involved are both physical and financial, not to mention aesthetic. Physically, refuse is frequently difficult to dispose of, partly because of its nature (e.g. one-way bottles or the like), and partly because of the fact that the sheer quantities of refuse involved tend in many instances to outstrip the disposal facilities. From a financial point of view, of course, the increasing amount of refuse generated each year of course puts a very substantial strain on the budgets of towns and municipalities.

The attempt to physically dispose of the refuse has included the proposition to utilize the refuse to the extent possible. This has involved attempts to compost the refuse in order to try to obtain humus for use in agriculture. However, no really satisfactory solution to this problem has heretofore become known. On the other hand, attempts to burn the refuse have also been only partially successful because the high percentage of ash residue, and the attendant disposal problems relative to the same, have made it economically inadvisable to resort to this disposal method.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the invention to overcome the disadvantages outlined above.

More particularly, it is an object of the invention to provide an improved method of processing refuse.

Still more particularly, it is an object of this invention to provide a method by which household, forestry and agricultural refuse can be processed in such a manner as not only to dispose of it physically, in order to rid oneself of it, but so as to actually convert the refuse into commercially utilizable semi- finished products.

In other words, the invention proposes to deal with the refuse-disposal problem by utilizing the refuse to the extent possible in a positive manner, namely by converting it into useful products. Evidently, this not only achieves one object, namely to dispose of the refuse, but it eliminates the expenditures of money heretofore required for disposing of the refuse, it eliminates the need to find physical locations or plants for disposal of the refuse, and even more importantly, in an age of shrinking physical resources the invention makes it possible to utilize the refuse itself as such a resource, namely as a basic raw material from which to make useful products.

In keeping with these objects, and others which will become apparent hereafter, one feature of the invention resides, briefly stated, in a method of processing refuse according to which a quantity of refuse be it household, forestry of the agricultural variety, is subjected to aerobic decomposition in order to form an aerobic decomposition substrate having a liberated fiber content. This substrate is then subjected to a treatment whereby its moisture content is adjusted within a predetermined range, preferably below 10%, and results in the conversion of the substrate into a finely structured essentially dry fibrous mass containing various particle sizes with the term "particle" as utilized herein referring to fibrous as well as non-fibrous particles. The fibers may be of various lengths and may be more or less straight or curled or rolled up. In any case, the mass is then admixed with the hardenable binder material, preferably a synthetic plastic resin, and then the resulting mixture is shaped to a predetermined configuration which it retains as the binder material hardens. It is preferred to use a binder material which is thermo-setting and the admixture is preferably subjected to pressure as the binder material hardens.

The refuse is advantageously composed of refuse which is the product of existing refuse composting installations wherein heretofore it was attempted to convert refuse to humus capable of utilization in agriculture. In this manner it is possible to continue to utilize such installations and to convert their output into commercially useable products.

A dye or coloring agent may be admixed with the mass and/or the binder material so that the finished product can have the desired coloration. Furthermore, at any stage of the processing steps a combustion-retarding agent can be added in order to retard or prevent combustion of the finished product. Evidently, the product can be shaped to many different configurations so that it may have the form of plates or panels and can be used in the building industry, or it may have other shapes. Insecticides and/or fungicides may also be added in addition to or in lieu of combustion-retarding agents, to prevent the deposition of insect eggs or the hatching of live insects from the same, either on or in cracks, pores or the like of the finished article. Insofar as fungicides are concerned, this avoids the development of mold if the finished article comes in contact at a later time with moisture. The density of the finished article may be influenced as desired by adding thermoplastic materials to the mass of fibrous matter.

Prior to subjecting the refuse to aerobic decomposition, hard articles such as rocks, metal parts or the like may be removed therefrom. Usually, the dry fibrous mass will be admixed with dust and particles of heavy specific gravity, such as rocks and metallic pieces, which of course are usually a part of refuse, especially the household refuse. It will also contain a coarse fiber fraction and the length of the fibers in the mass will vary greatly. If the fibers have become rolled up during processing, different diameters in the thus-formed rolls are observed. If the mass is formed to make plates or panels for building purposes, the heterogeneous structure of the mass which is converted into such panels has been found to be disadvantageous, in that thin plates of 10-15 mm. thickness are required for the interior structure of buildings and also particularly for furniture construction and need very frequently have aesthetically pleasing rather smooth surfaces. On the other hand, insulating panels of a mixture of fiber material obtained according to the invention with cement, should have coarse and rather long fibers. Also, a uniform fiber length may be desired in order to obtain certain values of strength in the finished product.

The present invention therefore proposes according to a further concept to segregate the dry mass obtained into a plurality of fractions, including a finest fraction and a coarsest fraction. It has been found advantageous but not mandatory to segregate such fractions and to use only the finer fractions for further processing whereas the coarsest fraction is dealt with separately, for instance by subjecting it to mechanical size reduction and returning it again to the segregation process.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a diagrammatic illustration showing a series of operating stages in the method of the present invention;

FIG. 2 is a front view of an apparatus for carrying out the invention; and

FIG. 3 is a side view of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Before entering into a detailed description of the Figures, the following example will serve to characterize the present invention.

A quantity of the usual household refuse contaiing rocks, bottles, metal parts and the like, as well as wet refuse, paper and the like, was first subjected to a segregation step in which the hard articles such as the rocks, bottles and metal parts were removed. Thereupon the remainder of the refuse was subjected to mechanical comminution. The refuse was then homogenized and subjected to an aerobic decomposition process with a compost resulting, having a content of 44.21% water and 55.79% dry substance. This compost was subjected to the influence of an air stream whose temperature upstream of the compost was 400.degree.C. and whose temperature downstream of the compost was 140.degree.C. As a result of contact with the air stream the compost was heated to 100.degree.C. and dried to a final moisture content of approximately 5%. The total quantity loss resulting from such drying process was 75.42% including the loss of moisture and the loss of a certain amount of dry substance.

The dried compost, now constituting a fibrous mass, had the following composition:

carbon 33.19% hydrogen 4.91% oxygen 12.16% nitrogen 1.02% sulphur 0.29% chlorine 1.4% phosphorous 0.37% ash 44.06%.

Heating and drying of the compost at 180.degree. C. temperature resulted simultaneously in sterilization of the material, and subsequent tests failed to show the presence of any bacteria.

The resulting matter was a mass which was dry, neutral, and fibrous as well as odorless. A quantity of 460 grams of this mass was admixed with 90 grams of woodchips. A quantity of 120 grams of ureaformaldehyde resin and 30 grams of an accelerator were mixed separately under intensive stirring and then admixed slowly--again under intensive stirring--with the mixture of 460 grams of fibrous mass and 90 grams of woodchips. After the mixture of ureaformaldehyde resin and accelerator--together constituting a hardenable binder material--was intermittently admixed with the combination of fibrous mass and woodchips, the resulting mixture was arranged in a layer of 7 cm thickness on a Teflon (trademark) support with which it was placed into a press that had been preheated to approximately 130.degree.-140.degree.C. In this press the mixture was subjected for a period of 12 minutes to constant pressure of 30 kg/cm.sup.2. It was found advisable not to let the temperature drop below 130.degree.C. during this molding process.

The shaped article resulting from this operation, namely a plate, was permitted to slowly cool, until complete hardening of the binder material and in order to assure polycondensation. The finished plate had a thickness of 1.5 cm., and the visual appearance of the conventional fiber board panel with the fiber structure analogous to that of conventional fiber board panels, was clearly visible with the naked eye. No coloring agent was added, but this could have been admixed with the ureaformaldehyde resin if it had been desired to impart to the finished plate a particular color.

The refuse as it is derived from household sources may includes bones, paper, cardboard, plastic discarded packages, meats, vegetables, wood, ash and so on. An aerobic decomposition substrate can be produced by any aerobic decomposition of the refuse, but for accelerating the decomposition process the refuse is composted in a suitable tank. Fungicides and insecticides may be added up to 20% of the quantity of the binder material. Ureaformaldehyde and phenolic resin can be used for binder materials, and suitable accelerators are available and well known.

Referring now to FIG. 1, the various steps of the novel process will now be illustrated and discussed, based on this diagrammatic figure.

Refuse, that is household refuse, agricultural refuse and/or forestry refuse is generally identified with reference numeral 1 and is admitted via a suitable gripper 2 into a rotating fermentation drum 3 of the type which is known per se. During the decomposition period which may last between 2 and 4 days, the refuse is subjected in the drum 3 to an aerobic decomposition process and is also subjected to size reduction due to the rotation of the drum. When the decomposition process is completed, the refuse leaves the drum 3 as fresh compost or substrate and then is made to fall onto a belt conveyor 4 from where it is conveyed via a chute 5 into a drying oven 6. In the latter the substrate or intermediate product is subjected to drying to reduce its water content to below 10%, and it is also sterilized. A ventilator 7 is provided for withdrawing the liberated gases of the oven 6 via a cyclone 8, a conduit 9 and a horizontal tube 10 which has a downwardly directed opening 11 preceded, in the flow direction of and air stream gases by a baffle 12. The opening 11 and baffle 12 serve to reduce the flow speed of the gases and thus permit a descent of coarse particles of heavy specific weight, for instance stones, so that these will fall through the opening 11.

The cyclon 8 yields a fiber granulate or fiber material which is now admitted into an enclosed bucket elevator 14 and from the same via a slide 15 into the inlet opening 16 of a screen housing 17. The housing 17 is mounted on springs (not separately illustrated) so that it can vibrate and oscillate and is provided with a similarly non-illustrated vibratory drive. Such drives are well known and require no detailed discussion; their purpose is to transmit vibration to a component, in this instance to the housing 17.

Mounted in the housing 17 in vertically superimposed relationship are the screens S1, S2, S3 and S4, as well as a receptacle S5. The mesh of the screens decreases in downward direction, that is the screen S1 has the largest mesh and the screen S4 the smallest. Each of the screens S1-S4 as well as the receptacle S5 have an outlet opening. The largest or coarsest fraction is, of course, retained on the screen S1 because due to the large mesh thereof all but the coarsest matter will pass through it. The fraction retained by the screen S1 is advanced by a conveying device 18 to a comminutor 19 wherein it is mechanically subjected to a reduction of its size, that is it undergoes comminution. Once it has been comminuted, this fraction is returned by the conveying device 20 to the inlet opening 16 of the housing 17 and once again passes through the segregating cycle. A suction conduit 21 communicates with the opening 16 and is connected via a cyclone 22 with the suction intake of a centrifugal blower 23. Of course, other suction sources could be utilized. The blower 23 draws air through the outlet openings of the screens S1-S4 as well as the outlet opening of the receptacle S5. The air is further drawn to the funnel 13 and the elevator housing 14. Due to this, dust, and some of the smallest fraction is withdrawn from the fibrous mass admitted via the inlet opening 16, and is separated in the cyclone 22 from the airstream. In addition, the air which is aspirated by the blower 23 provides for cooling of the still warm or hot fibrous matter in the bucket elevator housing 14 and in the housing 17. Finally, clogging of the screens S1-S4 by dust and the inevitably resulting decrease in efficiency, is avoided by this measure.

The material from which the coarsest fraction has already been removed, now passes through the screens S2, S3 and S4. The screen S2 retains a fraction which is finer than the coarsest fraction and is designated as F2. The screen S3 and S4 retain the fractions F3 and F4, with the latter being the finest fraction. The retained fractions F2, F3 and F4 are withdrawn by respective centrifugal blowers 24, 25 and 26 via conduits 27, 28 and 29. During such withdrawal the fractions pass through air sifting or separating devices 30, 31 and 32, respectively. The flow speed of air in the devices 30-32 is so selected that the respective fibrous material of the fraction being processed will float upwardly with the air in the device, whereas the heavier particles of the fractions will drop downward and leave the respective device 30, 31 or 32. These particles can then be added to the particles which issue from the opening 11; inasmuch as such particles are mostly stones or glass pieces, they can be deposited in suitable outdoor dumps without any danger of environmental contamination.

The fractions F2, F3 and F4, which have now been cleaned in the devices 30-32, respectively, of heavy contaminants, are then drawn by the air aspirated by the blowers 24-26 into separate storage units. The portion of the finest fraction F5 which has been drawn into the cyclone 22 and separated therein from the airstream is also admitted into a storage unit. From the container S5 the smallest fraction is advanced via a conveying device 33 into the wet separator 34 shown in FIGS. 1 and 2. In this separator the heavy particles such as grains of sand and pieces of glass, are separated from the remainder of the fraction and are removed separately via a conveyor belt 35, to be introduced into a storage unit 36. The light-weight components of the finest fraction are deposited wet onto a conveyor belt 37 which advances them to an intermediate storage device F'5 from where they are transported by the conveying device 38 through the funnel 5 into the drying apparatus 6, to be dried and subsequently to be returned into the segregating cycle.

It has been observed that the individual fractions F2-F5 are of very uniform structure and are largely free of heavy contaminant particles. These thus segregated and cleaned fractions can now be admixed with a binder as outlined earlier and can be pressed in presses 39 or 40 to form one-layer plates 41, or to form in any desired combination three or multiple layer plates 42 or any other desired shape. FIG. 2 shows details of the wet separator 34 and FIG. 3 is a side view of FIG. 2. The separator 34 has a container 50 which is closed at the top and provided with a lateral connecting flange 51 to which there is secured an outlet housing 52. The latter is supported on supports 54. An endless conveyor belt 35, driven by a motor 55 is mounted in the housing 52 and extends diagonally into the housing 50. Four (corresponding to the number of fractions) separating funnels 56 extend from above into the housing 50 and at each of the funnels 56 there is arranged, ahead of or in front of the rear wall, a deflecting baffle 57 which defines at its free end with the rear wall a slot 58. A water-conduit 59 terminates in the rear wall and is connected with the supply conduit 70 via a reducing valve 60. A further reducing valve 61 is interposed in an additional conduit 62 which also communicates with the supply conduit 70 and communicates with the interior of the housing 50.

Each of the funnels 56 is provided at its front side with an overflow edge joined by a slide or chute 63 which discharges onto the conveyor belt 36. The latter is driven by a motor 64, and located below the belt 36 is a collecting container 65 with an outlet 66.

When the device 34 is operated, the housing 50 is filled with water to the overflow edges of the funnels 56 via the conduit 70, the reducing valve 61 and the conduit 62. The supply of water via the conduit 62 is maintained during the entire operation of the device 34. Water is further admitted via the conduit 59 into the funnels 56, and enters into the same via the slot 58. This means that in the respective funnels 56 there exists a flow of water from below in upward direction, and at the surface of the funnel a flow of water from the slot 58 towards the overflow edge and the chute 63. The finest fraction F5 received in the receptacle S5 is poured into the funnels 56, from above. The flow of water in the device 34 is adjustable with the valves 60 and 61, and in particular in such a manner that the flow is not strong enough to prevent the heavier particles of the fraction in the funnels 56 from dropping downwardly counter to the flow of water, but is strong enough to carry along the lighter particles which are those desired to be recovered, to the chute 63 and the conveyor 36. The heavier particles, however, descend under the force of their own weight in the flow of water counter to the flow direction thereof, to become deposited on the conveyor 35 which carries them out of the housing 50. This means that at the outlet end of the conveyor 35, the heavier particles can be recovered, and that at the outlet end of the conveyor 36 the lighter particles of the finest fraction can also be recovered.

It is also possible, although not specifically illustrated, to dry the lighter particles recovered at the outlet end of the conveyor 36 in a separate non-illustrated drying apparatus and to convey them from there into the storage unit provided for storage of the finest fraction F5.

The admixing of the individual fractions, which latter may in turn be admixed in any desired ratio or be utilized separately, with a binder can be carried out in the manner outlined earlier, and similarly, the resulting mixture can be further processed as outlined earlier in order to obtain shaped bodies therefrom. Organic or inorganic binders may be used, particularly such duroplastic binders as epoxy or polyurethane resins, or else thermoplastic bituminous substances combined with carbohydrate resins or analogous matter. Also, mineral-based fibers of cement, gypsum or alkali-silicate mixtures can be employed.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in a method of processing refuse for conversion into shaped bodies, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

Claims

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. A method of processing refuse for conversion into shaped bodies, comprising the steps of subjecting a quantity of refuse containing liquid and solid constituents to aerobic decomposition so as to liberate the fiber content of said refuse; treating the resulting product to sterilize said product, adjust the moisture content of said product to within a predetermined range and convert said product into a mass of substantially dry heterogeneous fiber-containing matter; segregating said mass into a plurality of fractions including one fraction containing the matter of largest particle size, the remainder of said fractions containing the matter of smaller particle size and including a fibrous component and another component; separating said fibrous component from said other component; and converting said fibrous component into at least one shaped body.

2. A method as defined in claim 1, said remainder including at least two fractions; and wherein the step of separating said fibrous component from said other component is performed individually for each of the fractions of said remainder.

3. A method as defined in claim 1; and further comprising the step of isolating said one fraction from said remainder.

4. A method as defined in claim 1, wherein said other component comprises particles of higher specific gravity than said fibrous component.

5. A method as defined in claim 2, said other component including particles of higher specific gravity than said fibrous component; and wherein the step of separating said fibrous component from said other component comprises entraining the respective fractions separately with a flowing medium and conveying the entrained fractions vertically from a lower level to a higher level; and regulating the flow speed of said medium to be greater than the floating speed of the fibrous component of the respective fraction but less than the descending speed of the particles of the respective fraction.

6. A method as defined in claim 1, wherein the step of segregating comprises separating said mass into at least four of said fractions.

7. A method as defined in claim 1, further comprising the steps of subjecting said one fraction to mechanical particle-size reduction; and returning the thus reduced one fraction to the third-mentioned step.

8. A method as defined in claim 1; and further comprising the step of subjecting said mass to gravity-segregation for removal of particles of high specific gravity, prior to the step of segregating said mass into fractions.

9. A method as defined in claim 1, wherein the step of segregating comprises screening said mass.

10. A method as defined to claim 5, said fractions including a finest fraction; and wherein the medium for entraining said finest fraction is water, and the medium for entraining the other fractions is air.

11. A method as defined in claim 10; and further comprising the steps of recovering said finest fraction from the water, and drying the recovered finest fraction.

12. A method as defined in claim 1, wherein the step of segregating said mass comprises admitting said mass onto a series of superimposed screens with the mesh of each subjacent screen being smaller than that of the superimposed screen.

13. A method as defined in claim 12, said other component including particles of higher specific gravity than said fibrous component; and wherein the step of separating said fibrous component from said other component comprises passing a stream of air from below through said series of screens for entraining the finest one of said fractions, the flow speed of the air being selected to be greater than the floating speed of the fibrous component of said finest fraction but less than the descending speed of the particles of said finest fraction; and passing the air stream with the entrained fibrous component of said finest fraction into a cyclone.

14. A method as defined in claim 12, said other component including particles of higher specific gravity than said fibrous component; and wherein the step of separating said fibrous component from said other component comprises conveying a respective fraction separately in a vertical stream of flowing medium from a lower to a higher level; and regulating the flow speed of said medium to be greater than the floating speed of the fibrous component of the respective fraction but less than that of the particles of the respective fraction.

15. A method as defined in claim 14, said fractions including a finest fraction; and wherein said medium is water for said finest fraction, and air for the other fractions.

16. A method as defined in claim 15; further comprising the steps of separating said finest fraction from the water, drying the thus separated finest fraction, and returning the dried finest fraction to the third-mentioned step.

17. A method as defined in claim 1, wherein the step of converting said fibrous component comprises admixing the same with a binder material, and press-shaping the thus obtained substance to form shaped bodies therefrom.

18. A method as defined in claim 17, wherein said binder is a durable synthetic plastic.

19. A method as defined in claim 17, wherein said binder is a thermoplastic synthetic material.

20. A method as defined in claim 17, wherein said binder is a mineral binder.

21. A method as defined in claim 17, wherein the step of press-forming is carried out in a flat press.

22. A method as defined in claim 17, wherein the step of press-forming is carried out in an extrusion press.

23. A method of processing refuse and converting it into shaped bodies, comprising the steps of subjecting a quantity of refuse composed of liquid and solid constituents to aerobic decomposition so as to liberate its fiber content; treating the resulting product to sterilize it, adjust its moisture content to at most 10%, and convert it into a substantially dry fibrous mass having a substantial fiber content; admixing said mass with a hardenable binder material; shaping the resulting mixture under pressure so as to compress and form it into a shaped body; and effecting hardening of said binder material to thereby convert said body into a rigid structural element.

24. A method as defined in claim 23, wherein the adjustment of the moisture content comprises adjusting said moisture content to be less than 10%; and wherein said binder material is a synthetic resin.

25. A method as defined in claim 23, wherein said binder material is a synthetic resin material.

26. A method as defined in claim 23, wherein the step of treating said product comprises heating the same to a temperature not substantially lower than 80.degree.C.

27. A method as defined in claim 23, wherein the step of effecting hardening of said binder material comprises subjecting said body to heat.

28. A method as defined in claim 23, wherein said binder material is an organic binder material.

29. A method as defined in claim 23, wherein said binder material is an inorganic binder material.

30. A method as defined in claim 23; and further comprising the step of admixing with said fibrous mass a color substance prior to shaping of said mixture.

31. A method as defined in claim 23; and further comprising the step of adding to said mixture, prior to shaping thereof, at least one substance from the group composed of insecticides, fungicides and combustion-retardants.