WO2010119419A1

WO2010119419A1 - Method of reclaiming asbestos and asbestos waste and plant for carrying out such method

Info

Publication number: WO2010119419A1
Application number: PCT/IB2010/051641
Authority: WO
Inventors: Fausto Tarozzi
Original assignee: Siti - B&T Group S.P.A.
Priority date: 2009-04-15
Filing date: 2010-04-15
Publication date: 2010-10-21
Also published as: ITMO20090092A1; IT1394081B1

Abstract

The method of reclaiming asbestos and asbestos-containing waste comprises the steps of: receiving said asbestos and asbestos-containing waste in a loose condition; heating said asbestos and asbestos-containing waste by heating means (50) to an asbestos molecular modification temperature, thereby obtaining an inert mass of asbestos and asbestos- containing waste; which method comprising: loading said asbestos and asbestos-containing waste into movable/carriable container means (2, 2') thereby obtaining loaded container means (2, 2'); moving said loaded containers (2, 2') within said heating means (50) at said molecular modification temperature for a predetermined time.

Description

METHOD OF RECLAIMING ASBESTOS AND ASBESTOS WASTE AND PLANT FOR CARRYING OUT SUCH METHOD

TECHNICAL FIELD

The invention relates to a method of reclaiming asbestos and asbestos- containing waste and a plant for carrying out such method, to convert asbestos and asbestos-containing waste into inert material masses, safe for the health.

BACKGROUND OF THE INVENTION

Methods have been long known, which are used for treating and transforming asbestos and asbestos-containing waste to make it safe for the health of people.

Asbestos is known to have the characteristic of releasing particles of microscopic size into the atmosphere, which particles are carried by air, and may be inhaled by humans and animals, and cause serious damages to health, or even death.

For this reason, the decision has been made to no longer use this material in industry, remove it from any product and destroy products that had been made in the past, prior to the discovery of the dangers of this material, which has generated large amounts of waste awaiting treatment and disposal.

Due to its heat-insulating properties, asbestos has been extensively used in a variety of industrial fields to make any type of insulating cladding or roofing, such as roofs of buildings, road and railroad vehicles, walls and cavities.

An international program has been started for total removal of this material from the environment and from the materials that still contain it and, due to its potential danger, removal treatment require highly skilled personnel and processes adapted to prevent spreading of volatile particles in the atmosphere.

Furthermore, the products to be removed have to be gathered in specially designed places, in which asbestos and asbestos-containing waste are later treated to make them harmless.

All prior art methods for treatment of asbestos and asbestos-containing products include a preliminary step in which products are crushed into pieces of adequate size for later processing.

In many cases, the pieces obtained from crushing and plate-like pieces are accumulated in the form of packs whose overall size allows introduction thereof into a combustion chamber of a kiln for treatment.

Nevertheless, these prior art methods suffer from the drawback of requiring prior crushing of asbestos-containing products.

This crushing step generates a large amount of particles that spread in the atmosphere, thereby creating hazards for the health of operators that carry out treatments of asbestos and asbestos-containing products.

In order to reduce these hazards, crushing is performed in plants equipped with an air filtering system for capturing suspended particles.

Nevertheless, on the one end this filtration does not ensures a perfect air purification, and on the other end it still creates an additional problem, i.e. the requirement of cleaning or disposing of asbestos particle-capturing filters.

Furthermore, an additional problem is that reclamation of asbestos waste handling and crushing units is also required. In other prior art methods of reclaiming asbestos and asbestos-containing waste, the latter undergoes treatment with liquid solutions that contain chemicals adapted to chemically change the molecular structure of asbestos and make it harmless.

Nevertheless, these further novel methods also suffer from the drawback that waste has to be crushed and that crushing shall occur with the waste in contact with or dipped in the liquid solutions in which, among the chemicals designed to make asbestos and asbestos-containing waste harmless, there are also acids hazardous to human health.

OBJECTS OF THE INVENTION

One object of the invention is to improve the state of the art.

Another object of the invention is to provide a method of reclaiming asbestos and asbestos-containing waste and a plant for carrying out the method that can make asbestos and asbestos-containing waste harmless, without requiring a waste crushing step prior to reclamation and without generating volatile asbestos particles susceptible of being inhaled by people.

A further object of the invention is to provide a method of reclaiming asbestos and asbestos-containing waste and a plant for carrying out such method, that are safe, fully automatic and require no hazardous handling by personnel during the reclamation method.

A further object of the invention is to provide a method of reclaiming asbestos and asbestos-containing waste and a plant for carrying out such method, that requires no chemical-containing liquid solutions.

In one aspect, the invention relates to a method of reclaiming asbestos and asbestos-containing waste comprising the steps of: receiving said asbestos and asbestos-containing waste in a loose condition; heating said asbestos and asbestos-containing waste in heating means to an asbestos molecular modification temperature, thereby obtaining an inert mass, characterized in that it comprises: loading said asbestos and asbestos containing waste into movable/carriable container means thereby obtaining loaded container means; moving said loaded container means within said heating means at said molecular modification temperature for a predetermined time.

According to another aspect, the invention relates to a plant for carrying out a method of reclaiming asbestos and asbestos-containing waste, characterized in that it comprises: an area for receiving asbestos and asbestos waste in loose condition; an area for loading said waste onto movable/carriable containing means by automatic loading means; a heating area for heating said asbestos and asbestos-containing waste using heating means having a capacity; an area for filtering and discharging flue gases into the atmosphere, having filtering and discharging means.

Therefore, the method of reclaiming asbestos and asbestos-containing waste and the plant for carrying out the method allow reclamation of both asbestos and any asbestos-containing waste.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages will appear more clearly from the detailed description of a plant for carrying out a method of reclaiming asbestos and asbestos-containing waste, which is shown by way of illustration and without limitation in the annexed drawings, in which:

Fig. 1 is a schematic, very small-scale plan view of a plant for carrying out a method of reclaiming asbestos and asbestos-containing waste according to the invention;

Fig. 2 is an interrupted, larger-scale plan view of a part of a loading area for asbestos and asbestos-containing waste in a loose condition; Fig. 3 is an interrupted, larger-scale plan view of an area of an additional part of a loading area for asbestos and asbestos-containing waste in a loose condition, but already accumulated in pre-packaged containers;

Fig. 4 is an interrupted, larger-scale plan view of an area for cataloguing and storage of containers of asbestos and asbestos-containing waste;

Fig. 5 is an interrupted, larger-scale plan view of an area of a station for preparing containers of asbestos and asbestos-containing waste on modular conveyor means, for introduction thereof into heating means; Fig. 6 is an interrupted, larger-scale plan view of an area for heating containers of asbestos and asbestos-containing waste using discontinuous kilns;

Fig. 7 is an interrupted, larger-scale plan view of an area at the exit of the kilns of Fig. 6, for removal of asbestos and asbestos-containing waste, turned into a harmless inert material;

Fig. 8 is an interrupted, larger-scale plan view of a flue gas filtering area.

DESCRIPTION OF ONE EMBODIMENT OF THE INVENTION

Referring to Figure 1 , numeral 1 generally designates a plant for carrying out a method of reclaiming asbestos and asbestos-containing waste, briefly designated below as plant 1.

In Fig. 1 , broken lines define the areas of the system 1 in which the steps of the reclamation method of the invention are carried out, and namely numeral 100 designates an area in which asbestos and asbestos-containing waste are received and loaded in containers 2.

The asbestos and asbestos-containing waste, hereinafter generally referred to as waste, may come either from handling vehicles 3, on which it is collected in loose condition and from which it is discharged onto conveyors 4, as shown in a part 101 of the receiving and loading area 100, or from handling vehicles 3 in which it is loaded in containers 2' prepared and closed beforehand, as shown in a part 102 of the area 100.

An automatic robot 5 is placed in the part 101, which has a gripper member, for picking up the waste from the conveyor 4 and transferring it in containers 2.

These containers 2 are preferably combustible containers, as better explained hereafter, and may include, for instance, wooden or plastic cases or large closable bags, known in the art as "big-bags".

Once the containers have been filled, they are closed, for example cases are closed by a cover, and big-bags are closed by tying, and are picked up by automatic handling materials known as AGV (Automatic Guided Vehicles) or LGV (Laser Guided Vehicles), designated by numeral 6 in the figure, which carry them towards a cataloguing and accumulation area, designated by numeral 200.

The prepared containers that come from the part 102, after being unloaded from the handling vehicle 3, are also picked up and carried to the cataloguing and accumulation area 200.

In this cataloguing and accumulation area 200, each container is equipped with an identification code, which may be detected and stored by a central computer unit, that controls the plant 1 and is not shown because it is generally known to those skilled in the art.

The identification code contains data such as the date of arrival, packaging and storage, the place of origin, the type of waste contained therein, the weight and any other data useful for recognition. Still referring to Fig. 1 , it shall be noted the whole plant 1 is preferably enclosed in an isolating compartment, whose peripheral walls are designated by numeral 103, and which isolates it from the environment, so that the method of reclaiming asbestos and asbestos-containing waste can be carried out without causing asbestos particles to spread in the atmosphere.

Nevertheless, the isolating compartment may be also designed to be limited to the areas in which waste is handled to be introduced into the containers 2 or 2' and the latter are closed, without involving any danger of asbestos inhalation by people.

As shown in greater detail in Fig. 2, the robot 5 has an extensible arm 7 which extends from a base 8 that can rotate about a vertical, or substantially vertical axis of rotation "A".

In the part 101 of the area 100 a further isolating compartment is formed, whose peripheral walls are designated by numeral 9, which has an entry opening 10 protected by sliding doors 11 , through which the waste discharged by the vehicles 3 is received.

Still in Fig. 2, a sealed control room 12 is also formed in the additional tight compartment 9, which houses an operator 13 controlling the robot 5.

As shown herein, the empty containers 2 are fed to a movable surface 14, typically operated by rollers, which extends from the part 101 of the area 100 into the additional isolating compartment 9 and out of it, in the direction of arrow "B".

From the cataloguing and accumulation area 200, the containers 2 and 2' are picked up once again by automatic vehicles AGV 6 and carried into an area

300 in which they are prepared and loaded onto modular conveyor means, namely trolleys 15 of predetermined size, which are adapted to be introduced into heating means, such as the so-called discontinuous kilns, i.e. those in which the products to be heated are held still relative to the burners, and which are located in a heating area, designated by numeral 400.

Referring to Figures 4 and 5, it can be noted that in the preparation and loading area 300 the containers 2 and 2' are loaded onto trolleys 15 arranged in rows, e.g. composed of three adjacent containers, and then the trolleys 15 are placed on handling lines 16 in side-by-side relation to form a load 17 for a kiln 50, which load is substantially of the same size as the capacity of the kiln.

As shown in the Figures, in an exemplary embodiment of the plant 1 of the invention, four kilns 50 are provided, which are fed by as many handling lines 16, in turn fed by a further common handling line 18 transverse and perpendicular thereto, which sorts the loaded trolleys 15 out thereupon.

In order to prevent the generation of dioxin, the kilns 50 have secondary flue gas combustion chambers, designated by numeral 19, which open into pipes 20 that carry flue gases into an area, designated by numeral 600, where they can be filtered and released into the atmosphere.

In this area, flue gases are treated in a flue gas-to-fluid exchanger 21 to lower their temperature and the fluid is cooled in a dissipator.

Then, they are conveyed along a path equipped with batching devices 23 that add activated carbons and sodium bicarbonate and then pass through sets of filters 22, typically cascade bag filters, having a decreasing porosity from the inlet to the outlet, for hyperfiltration.

Finally, they are released into the atmosphere through chimneys 24.

At the exit of the kilns 50, the waste has an inert structure, due to the high temperature treatment it underwent in the kilns 50, and are removed by means of removal lines 25 placed at the exit of the latter and located in a further removal area, designated by numeral 500 in Figures 1 and 7.

In this removal area, there is a treated material collecting line 27, which is transverse to the removal lines 25 and receives the treated, inert waste from further vehicles AGV 6.

From this collection line 27 the waste is transferred to an additional conveyor line 28 which conveys it towards handling vehicles 29 that carry it to disposal places.

The method of reclaiming asbestos and asbestos containing waste is as follows: asbestos or asbestos-containing waste, in both cases in the form of pieces, generally referred to as waste, is conveyed by handling vehicles 3 towards the receiving and loading area 100 of the plant 1.

Waste may be carried either in loose form, i.e. with no protection, or prepackaged in closed containers 2'.

In the former case, which is the most hazardous, waste is introduced into the plant 1, which is normally closed by the walls 103 that isolate its interior from the outside environment that surrounds it, into the part 101 of the receiving area 10, and passes through the additional isolating compartment, closed by the walls 9 and having the entry opening 10 and the exit openings 10', all of which are protected by sliding doors 11.

In the additional compartment delimited by the walls 9, the robot 5, typically of anthropomorphic type, picks up the waste in pieces and transfers it into the containers 2, which may be of either reusable or preferably combustible, disposable type, that come in empty form from the movable surface 14. Then the containers 2, filled with waste, are closed, e.g. by a cover consisting of a sheet of combustible material and later placed on basements known as pallets and transferred into the cataloguing and storage area 200.

The closed waste-containing containers 2' are also transferred into the cataloguing and accumulation area 200.

All the containers are assigned an identification code, which contains data for automatic recognition thereof by a computerized control unit that manages, according to a management program, the automatic steps of the method of reclaiming asbestos and asbestos-containing waste, so that the position of each container 2 or 2' in the cataloguing and accumulation area 200, its content and its storage date may be known.

Then, a number of automatically guided vehicles 6, known as AGV, picks up a predetermined number of containers 2 and 2' stored in the area 200 and transfers them into the preparation and loading area 300 where they are loaded onto trolleys 15 of modular size, so that three of them in adjacent positions may be preferably loaded.

Each loaded trolley 15 is placed on the conveyor line 18, which distributes the trolleys among the conveyor lines 16, each leading to a kiln 50, typically but without limitation of the type known as discontinuous kiln.

A load 17 of adjacent trolleys is thus formed on each conveyor line 16, substantially corresponding to the capacity of the combustion chamber of each kiln 50.

Once a load 17 has been completed, it is introduced into its kiln 50, where it is heated to about 1200⁰C for a predetermined time, typically 30 hours.

This time may be adjusted according to the size and nature of the waste to be heated and then to be cooled for further handling, before extraction from the kilns 50.

The containers 2 and 2' are typically burnt to the waste modification temperature and are embedded in the waste in the modified form.

The flue gases generated by waste heating are treated in the secondary combustion chambers 19 and are conveyed through pipes 20 that carry them towards the exchangers 21 located in the filtering and discharge area 600.

A considerable amount of the thermal energy of flue gases is recovered in a known manner, e.g. by means of exchangers that supply it to electric current generators, whereas sodium bicarbonate and activated carbons are added to the flue gases by means of batching devices 23, and flue gases are transferred to respective filters 22 which have decreasing porosity and increasing fineness from the inlet to the outlet and are finally released into the atmosphere through the chimneys 24 in a fully purified form.

The converted, inert waste is conveyed through removal lines 25, which extend from the kilns 50 to the removal area 500, in which waste is loaded onto the additional conveyor line 28 that distributes it towards the vehicles 29, on which they are loaded, to be transferred to disposal sites.

It should be noted that the method of reclaiming asbestos and asbestos- containing waste is typically carried out in a compartment isolated from the atmosphere.

Nevertheless, once the containers 2 and 2' have been hermetically sealed, there may be areas of the plant 1 that are not isolated from the atmosphere, such as the heating area 400 or the preparation and loading area 300.

The above disclosed invention was found to fulfill the intended objects. The invention so conceived is susceptible to a number of changes and variants within the inventive concept: thus, for instance, the kilns 50 may be of the type known as continuous kilns, in which the waste to be converted moves relative to the combustion chambers.

All the details may be replaced by other technically equivalent parts.

In practice, any materials, shapes and sizes may be used as needed, without going out the scope of the following claims.

Claims

1. Method of reclaiming asbestos and asbestos waste comprising the following steps: - receiving said asbestos and asbestos waste in a loose condition;

- heating said asbestos and asbestos waste by means of heating means (50) to a molecular transformation temperature of the asbestos obtaining an inert mass; characterized by comprising: - loading said asbestos and asbestos waste into movable/carriable containing means (2, 2¹) obtaining loaded containing means (2, 2¹);

- moving said loaded containers (2, 2') inside said heating means (50) at said molecular transformation temperature for a predetermined time.

2. Method as claimed in claim 1 , wherein said providing said asbestos and asbestos waste comprises providing said asbestos and asbestos waste inside at least one delimited area (100, 200, 300, 400, 500, 600) atmospherically insulated from the external environment.

3. Method as claimed in claim 1 , wherein said containing means (2, 2¹) have a combustion temperature less than said molecular transformation temperature.

4. Method as claimed in claim 1 , characterized in that cataloguing said loaded containing means (2, 2') in a recognizable way by means of recognition data for obtaining catalogued and recognizable loaded containing means (2, 2') is provided before said heating.

5. Method as claimed in any of claims 1 to 4, wherein storing said catalogued and recognizable containing means according a cataloguing order is provided between said cataloguing and said heating.

6. Method as claimed in any of the preceding claims, wherein said heating comprises heating said asbestos, asbestos waste and containing means (2, 2') to said molecular transformation temperature, in such a manner to eliminate said containing means (2, 2') by combustion.

7. Method as claimed in claim 1 , wherein said containing means (2, 2') have a combustion temperature higher than said molecular transformation temperature.

8. Method as claimed in claims 1 and 7, wherein cooling and recovering said containing means (2, 2¹) is provided after said heating.

9. Method as claimed in any of the preceding claims, wherein said containing means (2, 2') are selected among containing chest, pallet, natural or synthetic fiber bags.

10. Method as claimed in claim 1 , wherein said receiving comprises closing said loaded containing means (2, 2') by closing means combustible to a temperature less than said molecular transformation temperature.

11. Method as claimed in any of the claims 1 to 10, wherein cooling and filtering combustion smoke by filtering means (22) are provided after said heating.

12. Method as claimed in claim 11 , wherein collecting thermal energy from said combustion smoke is provided before said cooling.

13. Method as claimed in any of the preceding claims, wherein said method is completely/partially carried out inside said delimited and atmospherically insulated area (100, 200, 300, 400, 500, 600).

14. Plant (1) for carrying out a method for reclaiming asbestos and asbestos waste characterized by comprising:

- an area (100) for receiving asbestos and asbestos waste in loose condition;

- a loading area of said waste onto movable/carriable containing means (2) by means of automatic loading means (5); - a heating area (400) for heating said asbestos and asbestos waste by means of heating means (50) having a capacity;

- a filtering and outside discharging area (600) of the combustion smoke by filtering means (22) and discharging means (24).

15. Plant as claimed in claim 14, comprising means for atmospheric insulation (103, 9, 11) of at least said loading area (100).

16. Plant as claimed in claim 14, wherein a cataloguing area (200) is provided between said loading area (100) and said heating area (400), said cataloguing area (200) being recognizable by means of cataloguing and storing means of said containing means (2, 2').

17. Plant as claimed in claims 14 and 16, wherein a loading area (300) of said containing means (2, T) onto modular transport means (15) is provided between said cataloguing and storing area (200) and said heating area (400), said modular transport means (15) being insertable into heating means and having a movable volume (17) substantially corresponding to said capacity.

18. Plant as claimed in any of the claims 14 to 17, wherein said heating means comprise furnaces (50) selected among discontinuous or continuous furnaces (50).