WO2014170517A1

WO2014170517A1 - Glass separation method

Info

Publication number: WO2014170517A1
Application number: PCT/ES2014/070279
Authority: WO
Inventors: Francisco Javier QUINTIERI FERNÁNDEZ; Albert Corominas Montoliu
Original assignee: Urbaser, S.A; Picvisa Machine Vision Systems, S.L
Priority date: 2013-04-18
Filing date: 2014-04-08
Publication date: 2014-10-23
Also published as: ES2408111B2; ES2408111A1

Abstract

The invention relates to a method for separating glass from a rejects fraction of municipal solid waste, comprising: subjecting material originating from a rejects fraction of municipal solid waste to a treatment in a rotary bioreactor; subjecting the material obtained from the rotary bioreactor to a first pre-screening with a 30 to 120 mm mesh filter; recovering the filtered fraction from the pre-screening; subjecting the filtered fraction from the first pre-screening to a second fines screening with a 5 to 30 mm mesh filter; recovering the unfiltered fraction from the second fines screening; separating light materials from the unfiltered fraction from the second fines screening, by means of sucking or blowing; subjecting the material not separated in the preceding step to a glass separation operation using an optical system that operates together with separation means.

Description

GLASS SEPARATION PROCEDURE

Field of the Invention

The present invention relates to the field of urban waste treatment, and more specifically to a process for the automatic separation of glass from undifferentiated urban solid waste.

Background of the invention

For several years there has been a growing interest in the separation of urban waste for both environmental and economic reasons. Indeed, the separation of urban waste allows the recycling of part of said waste (paper, plastic, glass) or its use to produce compost, recovered solid fuel, etc.

The first separation of solid waste is done at the household level, in which citizens must separate the solid waste produced and then put it in the appropriate containers. However, it is known that this separation is not optimal, and specifically in the undifferentiated waste container is a combination of solid waste of very different natures.

Specifically in the case of glass, its separation from undifferentiated urban solid waste, or is not done, or is done manually. In the case of manual separation, operators are dedicated to physically separate glass bottles and the like from the rest of the waste. This procedure obviously requires a large amount of labor and is therefore very expensive. In addition, it presents obvious risks for operators who may experience cuts and contamination resulting from injuries. On the other hand, even after the manual separation of bulky glass fragments, glass fragments of smaller size still exist in the urban solid waste rejection fraction, which does not they can be properly separated by manual means.

Various common process steps that facilitate the treatment of solid waste in general, such as screening, crushing, metal separation, etc., are also known in the art. However, there is still a need in the art for a procedure that allows automatic separation and recovery of glass from urban solid waste.

Summary of the invention

The present invention discloses an automatic glass separation process from a rejection fraction of urban solid waste. The process of the present invention is characterized in that it comprises the steps of:

- subject material from a rejection fraction of urban solid waste to treatment in a rotary bioreactor;

- subject the material obtained from the rotary bioreactor to a first pre-screening with a 30 to 120 mm mesh filter;

- recover the filtered fraction of the first previous screening;

- subject the filtered fraction of the first screening prior to a second screening of fines with a 5 to 30 mm mesh filter;

- recover the unfiltered fraction of the second fine screening;

- separating light materials by aspiration or blowing of the unfiltered fraction of the second fine screening;

- subjecting material not separated in the previous stage to glass separation by means of an optical system that acts only with separation means. Brief description of the figures

The present invention will be better understood with reference to the following drawing illustrating a preferred embodiment of the invention, provided by way of example, and which should not be construed as limiting the invention in any way.

Figure 1 shows a flow chart of a glass separation process according to a preferred embodiment of the present invention.

Detailed description of the preferred embodiments

As can be seen in the attached figure 1, the glass separation process of the present invention is based on an urban solid waste rejection fraction (MSW). This fraction is treated in a rotary bioreactor, such as BRS®, Biodrum®, Damage®, etc.

In said rotary bioreactor, the introduced material is defibrated but not broken (that is, it is not crushed). Thus, the material obtained at the exit of the rotary bioreactor has a spongy appearance, unlike a conventional crushing stage in which the material obtained has a more caked appearance. This aspect facilitates the subsequent treatment of urban waste until glass is obtained, as will be seen hereinafter.

In general, the size of the organic material, paper and various plastics introduced into the rotary bioreactor is reduced, while the glass is struck by the rotational movement of the equipment itself and is broken. The reduction in the size and shape of the organic fraction and paper is due to a biological process that occurs inside the rotating bioreactor.

Then, the material obtained is submitted to the output of the rotary bioreactor to a first pre-screening, using a 30 to 120 rom mesh filter. In this way the fine filtered fraction is separated from the rest of the materials, since in this fine fraction (less than 30 to 120 mm) approximately 90% of the glass to be recovered is found. Preferably, a 30 to 100 mm mesh filter can be used.

After recovering the filtered fraction of the first pre-screening, it can optionally be subjected (as indicated by dashed lines in Figure 1) to a separation of metals in order to ensure that a free flow of ferrous materials arrives, and thus more Controllable for the next stage. This metal separation can be carried out by any suitable means known in the art to extract the metals present in the filtered fraction of the first screening. For example, said fraction can be passed through a magnetic field (produced by an electromagnet or a permanent magnet) or those known as Foucault currents can be used. In the case of using a magnetic field, the separation of ferrous materials is provided, while Foucault currents facilitate the separation of both ferrous and aluminum materials.

Next, the filtered fraction (after optionally undergoing metal extraction) is subjected to a second fine screening. The choice of the diameter of the mesh passage will mean a greater or lesser loss of glass at the end of the procedure. According to the preferred embodiment of the present invention, a 5 to 30 mm mesh filter is used at this stage.

Next, the unfiltered fraction of this second screening of fines is recovered, which is mainly constituted by plastics, wood, glass, textile materials, ceramics, rubble and bones.

Subsequently, this unfiltered fraction of the second screening can be subjected to a second metal separation. optional, to improve the final performance of the procedure. Said optional second metal separation, as described above, can be by any conventional means known in the art (magnetic field, eddy currents or others).

Then, the separation of light materials is made from the unfiltered fraction of the second fine screening. This separation of lightweight materials is carried out by any appropriate means, such as for example by aspiration or by blowing. The lightweight materials separated at this stage can be sent, for example, to a conditioning system to convert them into a recovered solid fuel.

The heaviest material, not separated in the previous stage by blowing or aspiration, consists of rubble, ceramics, bones, glass, etc. This non-separated material is then subjected to a glass separation by an optical system that acts in conjunction with separation means. Specifically, there is an optical system that can distinguish the materials that are happening due to transparency and similar properties. According to the preferred embodiment of the present invention, an artificial vision optical system is used comprising a high resolution video camera, which allows to distinguish between glass and the rest of the materials that pass through its field of vision. According to an even more preferred embodiment, the resolution of the video camera of the optical system also allows the glass to be separated according to its color.

According to the preferred embodiment, the separation means acting in conjunction with the optical system are constituted by means of producing pressurized air. Thus, once the glass is detected by the optical system, it sends a signal to the separation means that then send a jet of pressurized air to push the glass that is passing and divert it from its initial path (to this type of separation is called "positive classification").

According to another embodiment of the present invention, a "negative classification" is performed. In this case, as in the previous one, the optical system detects if the material that is passing through its field of vision is glass or is another type of waste. Unlike in the previous case, the optical system will activate the separation means to push, by means of a jet of pressurized air, the residues other than glass; so that only the glass will continue its initial trajectory.

The procedure described above allows at least 90% of the glass present in the urban solid waste rejection fraction to be completely automatically recovered and with optimum purity. The separation performance and the purity of the final glass are determined, among other things, by the amount of optical systems used at the end of the procedure for the detection of the glass to be separated. Thus, according to a preferred embodiment of the present invention, instead of using a single optical system at this stage of the process, a plurality of cascaded optical systems are employed so that both the process performance and the performance are increased accordingly. glass purity finally obtained.

Although the present invention has been described with reference to a preferred embodiment thereof, the person skilled in the art will understand that modifications and variations can be applied thereto without thereby departing from the spirit and scope of the present invention.

For example, according to a further embodiment not shown in the figure, the process of the present invention comprises the previous step of separating bulky materials from the urban solid waste rejection fraction before being subjected to treatment in the rotary bioreactor. In this Bulk materials separation step can be employed any means commonly known in the art. For example, tromers, that is, rotary drums can be used that have perforations in their body so as to provide a size separation of the waste introduced therein.

In addition, as explained above, according to the preferred embodiment of the invention the system allows optional steps of metal separation after the respective screening. However, according to other alternative embodiments of the present invention the system completely lacks the possibility of performing such metal separation steps, or presents the possibility of performing only one of them.

According to a further preferred embodiment of the present invention, humidity below 70% is maintained throughout the process, more preferably between 5% and 70%, even more preferably between 30% and 70%, even more preferably between 30% and 60%, most preferably between 45% and 50%.

On the other hand, although glass detection for separation by means of an artificial vision optical system was described above, the person skilled in the art will understand that other types of optical systems can be used to detect glass without thereby departing from the scope of the present. invention. For example, additional embodiments of the present invention employ optical systems that distinguish glass from other waste by the use of X-rays, lasers, etc.

Claims

Procedure of separation of glass from a fraction of urban solid waste rejection, characterized in that it comprises the steps of:

- recover the filtered fraction of the first previous screening;

- recover the unfiltered fraction of the second fine screening;

- subjecting material not separated in the previous stage to glass separation by means of an optical system that acts together with separation means.

Method according to claim 1, characterized in that the material obtained from the rotary bioreactor is subjected to a first pre-screening with a 30 to 100 mm mesh filter.

Method according to any of the preceding claims, characterized in that it comprises the previous step of separating bulky materials from the urban solid waste rejection fraction.

Method according to any of the preceding claims, characterized in that the separation means acting in conjunction with the optical system are constituted by means of producing air under presure.

5. Method according to any of the preceding claims, characterized in that it comprises an additional step of separating metals after the first previous screening.

Method according to any of the preceding claims, characterized in that it comprises an additional step of separating metals after the second screening of fines.

7. Method according to any of claims 5 and 6, characterized in that the step of separating metals is performed by applying a magnetic field.

8. Method according to any of claims 5 and 6, characterized in that the step of separating metals is carried out by applying Foucault currents.

9. Method according to any of the preceding claims, characterized in that a humidity of less than 70% is maintained throughout the entire process.

10. Method according to claim 9, characterized in that a humidity between 5% and 70% is maintained throughout the entire process.

11. Method according to claim 10, characterized in that a humidity between 30% and 70% is maintained throughout the entire process.

12. Method according to claim 11, characterized in that a humidity of between 30% and 60% is maintained throughout the entire process.

13. Method according to claim 12, characterized in that a humidity comprised between 45% and 50% is maintained throughout the entire process.

14. Method according to any of the preceding claims, characterized in that the separation of glass is carried out by means of a plurality of optical systems arranged in cascade. Method according to any of the preceding claims, characterized in that the optical system is an artificial vision optical system comprising a high resolution video camera.