WO2008012444A2

WO2008012444A2 - Asbestos removal method. tool for implementing this method and system including such a tool

Info

Publication number: WO2008012444A2
Application number: PCT/FR2007/001292
Authority: WO
Inventors: Philippe Rovel
Original assignee: Emc Conception
Priority date: 2006-07-27
Filing date: 2007-07-26
Publication date: 2008-01-31
Also published as: FR2904247B1; WO2008012444A3; FR2904247A1; WO2008012444B1; WO2008012444A9

Abstract

Method of removal of asbestos from a building or similar, said building having walls (12) covered with a coating, said coating containing asbestos and having at least one first coat (15) of maximum thickness of 10 mm and a surface area that can be divided fictitiously into at least one zone (16). The method includes a step of vitrification of the first layer (15) of the coating by the application of a heat source directly on the zone (16), so as to render inert the asbestos contained in said zone (16).

Description

AT

Asbestos removal process. tool for the implementation of this method and system comprising such a tool.

The present invention relates to a method of asbestos removal of buildings, or the like, such as ships at the end of life, and to a tool for carrying out this method.

Asbestos has long been used in many materials and products due to its acoustic, thermal, heat and fire resistance, chemical inertness, mechanical strength and rot resistance. However, its adverse effects on human health led to a control and a gradual reduction of its use, followed by a total ban.

At present, asbestos removal operations take place in several constraining stages because they must respect safety standards for both the worker and the environment. The worker must indeed be provided with a combination and a respiratory system so as not to inhale friable asbestos dust, extremely toxic. His work is done in a confined area, divided into several compartments including two showers. This confined area has an air pressure lower than that of the outside air so that in the event of a leak, it is the outside air that enters the confined area, and not the other way around. An air renewal system must also be provided.

Asbestos, removed from its support can undergo a treatment to make it inert, that is to say modify it to make it nontoxic to humans. This treatment may consist of vitrification, as described in patents FR 2 853 846 or FR 2 690 093, the asbestos waste being incorporated in a particular oven making it possible to achieve very high temperatures. The waste may be previously packaged, for example by pre-bagging, as described in patent FR 2 746 037.

The asbestos removal conditions require drastic safety conditions without detoxifying the product. Alternative solutions have been found to allow waste removal in one step while making them inert. Thus, US Pat. No. 4,693,755 describes a process for removing asbestos from its support following the application of a cellulosic polymer-based composition which penetrates and dries asbestos dust so as to render it inert. Patent FR 2 875 720 describes an asbestos removal process using cold. Following the injection of liquid nitrogen, at a temperature between -40 ⁰ C and -196 ° C, asbestos congeals in its support and can be removed safely.

However, the vitrification solution of asbestos waste remains the most suitable solution. It makes it possible to render asbestos fibers inert. No risk of future pollution is no longer to be considered. The product obtained after vitrification can be valorized. However, the current solutions for vitrifying asbestos, consisting of heating asbestos-containing waste in an oven, and requiring the transport of waste asbestos from their place of removal to their place of cooking, although these waste pose a risk important for health.

This problem is all the more important for shipbuilding, since no shipyard in France is capable of dismantling ships and consequently their total asbestos removal, thus requiring long and expensive towing to foreign countries, in which the security conditions are non-existent.

The invention proposes to overcome these various disadvantages through an asbestos removal process, particularly suitable for ships at the end of life, to vitrify asbestos directly on its support without having previously removed the asbestos waste.

For this purpose the invention proposes a method of asbestos removal of a building or the like, said building having walls covered with a coating, the coating containing asbestos and having at least a first layer with a maximum thickness of 10 mm and a surface that can be fictitiously divided into at least one zone, characterized in that the method comprises a vitrification step of the first layer of the coating by the application of a heat source directly on the zone, so as to render the asbestos contained in said zone. Thanks to these provisions, it is possible to vitrify the coating directly on the walls.

This limits the emission of suspended fibers to protect operators and the external environment. In addition it allows to recycle the walls for other subsequent uses.

The invention also relates to a portable vitrification tool for heating a coating containing asbestos at very high temperatures, of the order of 1200 ⁰ C, and a system comprising this tool.

Thanks to these provisions the process is mechanized, which allows to protect the operators, and to improve the time necessary for the deconstruction of the building.

The invention will be better understood on reading the detailed description below, written with reference to the accompanying drawings, in which: FIG. 1 is a perspective view from below of the tool making it possible to implement the asbestos removal process according to the invention;

Figure 2 is a longitudinal sectional view of the tool shown in Figure 1; Figure 3 is a partial perspective view of a vessel equipped with a robot according to Figure 3, adapted to implement the method according to the invention; Figure 4 is a bottom view of the tool according to another embodiment; FIG. 5 is a sectional view along a vertical plane passing through line A-A of the tool represented in FIG. 4.

Figure 3 shows a portion of a ship 10 having walls 12 covered by a coating containing asbestos. The walls 12 may be constituted by a floor, side walls, ceilings or heating ducts or ventilation. The coating has a surface that covers all or part of that of the wall 12 on which it is disposed.

The asbestos-containing coating can be in various forms. This can be asbestos "flocked" obtained by mixing asbestos fibers with a binder and sprayed in a layer of 2 to 6 cm thick on the walls, it can be heat-resistant insulation obtained by mixing plaster and asbestos, having a thickness of a few centimeters. This can be asbestos-based floor tiles made of plastic and attached to the walls by an adhesive containing asbestos. Finally this can be asbestos paints. When the asbestos coating comprises a first layer less than 10 mm thick, preferably less than 3 mm thick, as shown in FIG. 2, the asbestos removal process consists in vitrifying the first layer of the coating by the application of a heat source directly on an area 16 of the surface of the coating. Vitrification makes it possible to modify the crystalline structure of asbestos by transforming it into a frozen state into an inert, inert, vitreous substance.

The heating is carried out at a temperature of at least 1000 ^° C., preferably at 200 ^° C., and makes it possible to vitrify the asbestos coating to a depth of a few millimeters, preferably between 0 and 3 mm, corresponding to the thickness of the first layer 15,

Inerting the coating makes it possible to recycle the wall 12 safely for the operator.

The heating is directly carried out on the coating covering the wall 12, thus avoiding a prior removal of the elements containing asbestos for their subsequent treatment. The vitrification zone 16 depends on the surface to be vitrified. In the case where the vitrification zone 16 is less than the surface of the coating, the vitrification step of the first layer of the coating is carried out by successive vitrification of each zone 16 forming the surface of said first layer 15. Thanks to these provisions it is possible to render inert a large surface of coating directly in the building. The vitrification is carried out progressively, by vitrifying zone by zone, until the vitrification of the total surface of the coating is obtained.

The asbestos coating may have a thickness greater than 10 mm. It is then formed of the first layer in contact with the wall and a second layer covering the first layer. The first and second layers are formed of the same material. It is then necessary to first remove the second top layer, so that the thickness coating remaining on the wall, forming the first layer, less than 10 mm, so that the vitrification operation can be effective.

The shrinkage can be achieved in different ways depending on the type of coating present on the wall. The shrinkage may be mechanical, for example by scraping with a spatula. This applies especially when the coating is flocking or asbestos insulation.

When the second layer of the coating consists of floor tiles glued to the wall and the first layer is constituted by the adhesive placed between the tiles and the wall, the tiles are previously removed. After cooling the adhesive constituting the first coating layer, it is vitrified according to the method described above.

When the vitrified coating is cooled, it is then possible to cut the walls into several pieces and dismantle a building, to enhance the steel or other material. The method as described above is implemented by means of a tool 18 shown in FIG. 1. The tool comprises a hermetic bell 20 adapted to create a hermetic space 22 with the wall 12 containing the coating zone 16 to vitrify . It further comprises heating means 24, arranged in the bell 20, and adapted to heat the zone 16 to at least 1000 ^° C. It also comprises suction means arranged in the bell 20 and adapted to create a depression in the bell to suck fumes and burnt waste.

The vitrification tool makes it possible to heat the asbestos coating to a temperature above 1200 ^° C. For this reason, the heating means 24 may be a flat burner, which is supplied with oxygen and with gas. It is obvious that any other suitable heating means can be integrated into the tool.

According to a first variant shown in Figures 1 and 2, the heating means is movably mounted in translation in the bell. The heating means is adapted to sweep an entire area to vitrify. According to a second alternative embodiment shown in Figures 4 and 5, the heating means 24 is fixedly mounted in the bell 20, and it is the tool 18 which is displaced in translation over the entire surface of the wall to be vitrified. For this purpose the bell 20 has wheels 34, allowing to slide along the entire surface to be treated without having to take off the bell 20 of the wall. The airtight bell 20 makes it possible to create a hermetic space, and put under vacuum, so as to prevent the asbestos fibers and the fumes from spreading outside during the vitrification step. The hermetic bell can be of refractory stainless steel, protected by thin layers of refractory concrete, adapted to isolate the heating zone from the outside. The bell has an opening 28, which is plugged by the wall during vitrification to form the hermetic space. The opening 28 has dimensions that correspond to the treated area 16. Thus, if the surface of the coating is larger than the opening 18 of the bell 20, the tool will successively vitrify zones having the dimensions of the opening of the bell, until the vitrification of the total surface is obtained. coating.

The suction means comprise an air intake 26 adapted to suck fumes and burnt waste resulting from the vitrification process. In addition, a mobile unit for suction and flue gas treatment is associated with the vitrification operation so as to guarantee the protection of the environment adjacent to the tool. The unit is disposed downstream of the suction means so as to reject unpolluted air.

The tool is preferably installed on a system, for example a robot, which can support it and guide its movement on the wall to be treated. The tool is equipped with a quick coupler 30 to be quickly put in place after the step of removing the second layer of asbestos coating. Thus the operators are kept at a distance from the risk areas, which reduces the hardness of work thanks to the radio control system of the tool.

Claims

1. A method of asbestos removal from a building or the like, said building having walls (12) covered with a coating, the coating containing asbestos and having at least a first layer (15) of a maximum thickness of 10 mm and a surface that can be fictitiously divided into at least one zone (16), characterized in that the method comprises a step of vitrifying the first layer (15) of the coating by the application of a heat source directly on the zone ( 16) so as to render the asbestos contained in said zone (16) inert.

2. asbestos removal process according to claim 1, wherein the surface comprises several zones (16) and the vitrification step of the first layer (15) of the coating is performed by successive vitrification of each zone (16) forming the surface of said first layer (15).

3. asbestos removal process according to one of the preceding claims, wherein the coating comprises a second layer covering the first layer (15), the method comprising the prior step of removing the second layer of the coating.

4. Tool for carrying out the method according to claims 1 to 3, characterized in that it comprises:

a hermetically sealed bell (20) adapted to create a hermetic space with the wall (12) containing the coating zone (16) to vitrify,

- Heating means (24), arranged in the bell (20), and adapted to heat the area to at least 1000 ⁰ C, - suction means arranged in the bell and adapted to suck fumes and burnt waste .

5. Tool according to the preceding claim, further comprising a smoke treatment unit and fibers disposed downstream of the suction means, so as to treat the fumes and burnt waste.

6. Tool according to one of claims 4 and 5, wherein the bell has an opening (28) whose dimensions define the area (16) coating to vitrify.

7. System comprising a tool and being adapted to move the tool on a surface, characterized in that it comprises a tool according to one of claims 4 to 6.