WO1992003235A1

WO1992003235A1 - Treatment of asbestos or like material

Info

Publication number: WO1992003235A1
Application number: PCT/GB1991/001393
Authority: WO
Inventors: Graham James Gwilliam
Original assignee: Graham James Gwilliam
Priority date: 1990-08-18
Filing date: 1991-08-16
Publication date: 1992-03-05
Also published as: AU8411991A; GB9018206D0

Abstract

The invention discloses a method of and apparatus for treating asbestos or other fibrous material so as to render the asbestos safe by encapsulating it in a sealant. The sealant is injected into the apparatus through a plurality of hollow injection needles (21) which are supported relative to one another, such as by a panel (20), and which are supplied with sealant by way of a manifold (22). The sealant is then cured, such as by introducing a gaseous or liquid hardener into the asbestos via the needles (21) or such as by ultraviolet radiation or electron bombardment. The appaatus can also be used to inject a wetting liquid, such as a surfactant, into the asbestos to facilitate asbestos removal as an alternative to encapsulation.

Description

Treatment of Asbestos or Like Material

This invention relates to a method of and apparatus for treating asbestos or other fibrous material (hereinafter referred to for convenience as

"asbestos") so as to render the asbestos safe or so as to wet the asbestos to facilitate its removal.

As is well known, asbestos dust is extremely dangerous to human beings and it is common practice these days to remove asbestos insulation in order to safe guard against potential danger. However, in some places there is so much asbestos to remove that the cost of removing it is prohibitive.

Accordingly, the present invention in some of its aspects seeks to provide a method of and apparatus for rendering the asbestos safe as an alternative to asbestos removal.

According to a first aspect of the invention, there is provided a method of treating asbestos so as to render it safe, the method comprising injecting a curable, liquid sealant into the asbestos, and curing the sealant in order to encapsulate the asbestos in the sealant. According to the nature of the sealant, it may be cured in any one of a number of different ways. It may for example be cured by a gaseous or liquid hardener. In this case, an appropriate hardener is introduced into the asbestos. Generally but not necessarily this will be done after the sealant has been injected into the asbestos. Alternatively, the sealant could be cured by ultraviolet radiation or electron bombardment or it could be cured by free metallic ions existing within the asbestos matrix.

In any event it is desirable that the sealant should be cured rapidly at least to an extent that the asbestos is self-supporting and bonded to its substrate, as otherwise the weight of the asbestos when injected with sealant may be such that the asbestos will fall

,away. The choice of sealant, and where appropriate the choice of hardener, should therefore be such that the asbestos is self-supporting in a very short time and typically in less than one minute. Complete curing could then continue over a matter of hours or even days.

In the event that the sealant does not cure rapidly, it may prove necessary to support the asbestos in some other way while the sealant cures.

Preferably, the sealant (and where appropriate the hardener) is fed into the asbestos from a plurality of hollow needles. Preferably, each needle has a closed pointed end and one or more apertures in its peripheral wall. Preferably, the needles have a maximum cross sectional dimension of 4mm. Advantageously, the needles are supported relative to one another and preferably, the liquid sealant is supplied to the needles from one or more manifolds. If both sealant and hardener are to be introduced into the asbestos, there may be two sets of needles, one for injecting the liquid sealant and the other for introducing the hardener into asbestos. Alternatively, each needle may be used to both inject liquid sealant and introduce gaseous or liquid hardener into the asbestos but in this case the needles may need to be purged with an inert gas or water between receiving the sealant and the hardener to prevent sealant setting within the needles.

According to a second aspect of the invention there is provided apparatus for encapsulating asbestos in a sealant, the apparatus comprising a plurality of hollow injection needles, and means supporting the needles relative to one another.

Preferably, the apparatus further comprises a manifold for supplying liquid sealant to the needles.

The manifold may have two chambers, one for supplying the liquid sealant and the other for supplying a hardener to the needles. In this case, some of the needles may communicate with one of the chambers and the other needles with the other chamber. Alternatively, each needle may communicate with both chambers.

Preferably, the apparatus also comprises means for supplying liquid sealant under pressure to one of the chambers in the manifold and means for supplying gaseous or liquid hardener under pressure to the other chamber in the manifold.

Preferably, each needle has a closed pointed end and one or more apertures in its peripheral wall for injecting the sealant, and where appropriate the hardener, into the asbestos. Preferably, each needle has a maximum cross sectional dimension of 4mm and typically of 2.5mm or less.

According to a third aspect of the invention, there is provided apparatus for injecting a liquid into asbestos to be removed, comprising a plurality of hollow injection needles and means supporting the needles relative to one another.

Preferably, the apparatus further comprises a manifold for supplying a wetting liquid to the needles.

According to a fourth aspect of the invention, there is provided a method of removing asbestos, comprising the steps of:-

(a) wetting the asbestos by injecting a wetting liquid into the asbestos using apparatus according to the third aspect of the invention, and then

(b) removing the asbestos.

According to a fifth aspect of the invention, there is provided portable asbestos treatment apparatus comprising a plurality of hollow injection needles, means supporting the needles relative to one another, and a manifold for supplying a liquid to the needles.

The invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which:-

Figure 1 is a vertical section through one embodiment of apparatus for treating asbestos, according to one or more aspects of the present invention,

Figure 2 is a sectional view of part of one of the needles of the apparatus shown in figure 1 on a much enlarged scale, Figure 3 is a side view of another embodiment of apparatus for treating asbestos and including needles similar to those shown in Figure 2 , and

Figure 4 is a plan view of the apparatus shown in Figure 3.

Referring to the Figures 1 and 2 of the drawings, the apparatus shown therein comprises a panel- shaped manifold 10 having two chambers 11 and 12 therein, and a plurality of injection needles 13 supported by the manifold 10.

The manifold 10 may be formed from an aluminum or plastics extrusion having upper and lower major sides 10a and 10b which are typically 600mm square. The manifold 10 also has a central partition wall 10c parallel to and interposed between the two major sides 10a and 10b. The partition wall 10c -separates the two chambers 11 and 12 one from the other. The chambers 11 and 12 could be much smaller than shown in Figure 1.

As best shown in Figure 2, each needle 13 has a closed pointed end 14 for insertion into asbestos insulation to be encapsulated in a sealant, and at least one, but preferably two or more apertures 15 distributed around the periphery of the needle for injecting a liquid sealant and/or a gaseous or liquid hardener into the asbestos. The end of each needle may be swaged to a point 14 as shown in Figure 2, but alternatively the pointed end 14 could be at the tip of an oblique ellipsoidal end surface. The apertures 15 are preferably slanted away from the pointed end 14 as shown on the left side of Figure 2 to prevent blockage when penetrating the asbestos, but alternatively the apertures 15 could be radial and the discharge ends of the apertures could be flared as shown on the right side of Figure 2.

The needles 13 are preferably formed of stainless steel to avoid corrosion and the apertures 15 are formed by spark erosion or drilling.

Typically, the outside diameter of each needle 13 is about 2.5mm and the apertures 15 typically have a diameter of between 5 and 30 thou. (0.127mm to 0.762mm) and typically about 0.30mm, but in any event the needle

(i.e. the part which is to penetrate the asbestos) should ideally have a maximum cross sectional dimension which is not greater than 4mm as anything larger could damage or disturb the surface of the asbestos to an extent that releases harmful fibres. The length of each needle 13 can vary according to the depth of insulation to be encapsulated. Longer needles may have apertures 15 which are distributed not only around the needle periphery but also along the length of the needle.

The manifold 10 has two inlets 18 and 19 communicating with the chambers 11 and 12 respectively and some of the needles 13 have apertures 16 communicating with the chamber 11 whilst other needles

13 have apertures 17 communicating with the chamber 12.

The apparatus also comprises means for supplying liquid sealant under pressure to one of the chambers, e.g. chamber 11, and means for supplying gaseous or liquid hardener under pressure to the other chamber 12.

The sealant may be in the form of an aqueous alkaline phenol formaldehyde polymer such as Borden Betaset Resin BSR-21 supplied by Borden (UK) Limited of North Baddesley, Southampton, England and the hardener may be in the form a volatile ester vapour such as a formic acid methyl ester available as Borden Betaset Hardener BSH-10 also supplied by Borden (UK) Limited.

Alternatively, the sealant may be in the form of a water-soluble, alkaline phenolic resole polymer and the hardener may be in the form of a liquid ester hardener, also available from Borden (UK) Limited as part of their Borden Alphaset Process. In order to encapsulate the asbestos in a sealant, the pointed ends 14 of the needles 13 are placed against asbestos insulation which may, for example, line the ceiling of a room, and the panel shaped manifold 10 is then driven towards the asbestos insulation so that the needles 13 penetrate the asbestos.

Liquid sealant is then supplied under pressure to the chamber 11 from where it is injected into the asbestos via respective needles 13 for a period of about 2 minutes. The supply of liquid sealant to chamber 11 is then cut off and gaseous or liquid hardener is supplied to chamber 12 under pressure possibly after purging the chamber 11 with inert gas or water. This hardener enters the asbestos via respective needles 13 and all needles are then immediately withdrawn from the asbestos.

During the injection process, the panel-shaped manifold 10 can be supported in position by hand or by one or more props.

As described above, each needle 13 communicates with only one of the chambers 11 and 12.

However, in an alternative embodiment, each needle 13 may be arranged to communicate with both chambers 11 and

12. However, in this case it may be necessary to purge the needles 13 of sealant with an inert gas or water prior to introducing hardener into the needles and the needles may also need to be equipped with an appropriate one way valve arrangement.

It is also envisaged that the needles 13 could be slidably mounted in the manifold 10 to accommodate uneven substrate surfaces. In this case slidable seals will have to be provided between the needles and the manifold and the side of the manifold remote from the pointed ends of the needles may have to be given some degree of flexibility.

The concept of using a plurality of needles supported by a common manifold can also be applied to an injection system for wetting asbestos prior to asbestos stripping. In this case the apparatus may differ from that described above in that the manifold need only define a single chamber for supplying a wetting agent, such as water or a mixture of water and a surfactant, to the needles.

Referring now to Figures 3 and 4 of the drawings, the apparatus shown therein comprises a rectangular panel 20 having apertures therein supporting a plurality of injection needles 21 which are similar to the needles 13 of Figures 1 and 2. The needles 21 project from one major surface of the panel 20 and, as shown, are arranged in regularly spaced, parallel relationship. The needles 21 are releasably attached to the panel 20 for ease of replacement or cleaning.

An elongate manifold 22 is secured to the other major surface of the panel 20, and extends from one end of the panel to the other, midway between opposite sides of the panel. The manifold 22 is connected to the ends of the needles 21 by T-couplers 23, flexible pipes 24 and elbow couplers 25. The flexible pipes 24 are readily removable from respective couplers 23 and 25 for ease of cleaning.

Sealant and, if appropriate, hardener is supplied under pressure to the manifold 22 by way of a rigid pipe 26 which also serves as a handle and this pipe 26 is equipped with an on/off valve operated by a pivotal lever 27.

Typically, the panel 20 is about 30cms wide and 45cms long and is equipped, for example, with 24 needles. Alternatively, it could, for example, be about 45cms square and be equipped, for example, with 36 needles, but in this case it may be necessary to provide two spaced manifolds 22. The manifold 22, couplers 23 and 25, and pipes 24 could be enclosed in a cover (not shown) .

The apparatus shown in Figures 3 and 4 can be used in similar manner to the apparatus of Figures 1 and 2 to inject sealant into asbestos. However, if a hardener has to be introduced into the asbestos, this will be introduced through the same needles as the sealant, and in this case it may be necessary to purge the apparatus with an inert gas or water prior to introducing the hardener.

It is however envisaged that it may not be necessary to introduce a hardener as it may be possible to use a sealant which can be cured, for example, by ultraviolet radiation or electron bombardment.

The apparatus shown in Figures 3 and 4 could also be used to inject a wetting agent, such as water or a mixture of water and a surfactant, into asbestos to facilitate asbestos removal as an alternative to encapsulation.

The apparatus may comprise only a single row of needles attached to a common support and a manifold in or on the support for distributing a sealant and, where appropriate a hardener, or a wetting agent, to the needles.

Claims

C A I M S

1. A method of treating asbestos (as herein defined) in order to render it safe, the method comprising the steps of:-

(a) injecting a curable, liquid sealant into the asbestos, and

(b) curing the sealant in order to encapsulate the asbestos in the sealant.

2. A method as claimed in claim 1, wherein the sealant is curable by a gaseous hardener and step (b) includes introducing the gaseous hardener into the asbestos under pressure.

3. A method as claimed in claim 1, wherein the sealant is curable by a liquid hardener and step (b) includes introducing the liquid hardener into the asbestos under pressure.

4. A method as claimed in claim 1, wherein the sealant is curable by ultraviolet radiation and step (b) includes subjecting the asbestos containing the sealant to ultraviolet radiation.

5. A method as claimed in claim 1, wherein the sealant is curable by electron bombardment and step (b) includes subjecting the asbestos containing the sealant to an electron beam.

6. A method as claimed in any one of the preceding claims, wherein the sealant is fed into the asbestos from a plurality of hollow needles.

7. A method as claimed in claim 6, wherein each needle has a closed pointed end and one or more apertures in its peripheral wall.

8. A method as claimed in claim 6 or claim 7, wherein the needles have a maximum cross-sectional dimension of 4mm.

9. A method as claimed in any one of claims 6 to

8, wherein the needles are supported relative to one another.

10. A method as claimed in any one of claims 6 to

9, wherein liquid sealant is supplied to the needles from a manifold.

11. Apparatus for encapsulating asbestos in a sealant, the apparatus comprising a plurality of hollow injection needles, and means supporting the needles relative to one another.

12. Apparatus as claimed in claim 11, including a manifold for supplying liquid sealant to the needles.

13. Apparatus as claimed in claim 11 or claim 12, wherein the manifold has two chambers for supplying the .liquid sealant and a hardener, respectively, to the needles.

14. Apparatus as claimed in any one of claims 11 to 13, wherein each needle has as closed pointed end and one or more apertures in its peripheral wall.

15. Apparatus as claimed in any one of claims 11 to 14, wherein each needle has a maximum cross sectional dimension of 4mm.

16. Apparatus for injecting a liquid into asbestos to be removed, comprising a plurality of hollow injection needles and means supporting the needles relative to one another.

17. Apparatus as claimed in claim 16, including a manifold for supplying a wetting liquid to the needles.

18. Apparatus as claimed in claim 16 or claim 17, wherein each needle has a closed pointed end and one or more apertures in its peripheral wall.

19. Apparatus as claimed in any one of claims 16 to 18, wherein each needle has a maximum cross sectional dimension of 4mm.

20. A method of removing asbestos, comprising the steps of:

(a) wetting the asbestos by injecting a wetting liquid into the asbestos using the apparatus of any one of claims 16 to 19, and

(b) removing the asbestos

21. Portable asbestos treatment apparatus comprising a plurality of hollow injection needles, means supporting the needles relative to one another, arid a manifold for supplying a liquid to the needles.