This invention relates to a method of recovering material detrimental to the environment, in such a. way, that the material cannot bedspread to the surroundings and thereby detrimentally affect the environment and human beings. One such material a.o. is asbestos.

Asbestos is generally present in modern society, although its fields of application now are ever increasingly re¬ stricted, because asbestos is harmful to human beings. Asbestos by its nature adheres in the lungs when it is inhaled and from there spreads to other parts of the body. Asbestos has been very widely used as insulation material in the construction field, in heating install¬ ations, and as a fire-retarding material in floor struct¬ ures, partition walls and the like. Owing to the increas- ing severeness of environmental problems, reat difficulties have arisen when buildings and installations, in which asbestos had been used, are demolished and reconstructed.

It is known today at the demolishing of a-sbestos and re¬ construction of asbestos-loaded areas to suck the asbestos material to a container, from which the asbestos material - now decomposed to dust-like material is removed packed in plastic bags. These bags are transported, for example, to garbage stations where they are stored buried. It is easy to understand that during all these handling oper- ationstthere is risk that the asbestos finds its way outside the bags, both when the asbestos is being filled into the bags, and during their transport when a bag is damaged, and also when the garbage station lateron is digged up and the dust-like asbestos thereby is exposed. In the case of great asbestos amounts, the container is transported directly, for example, to the garbage station where water is poured over the asbestos to prevent dust formation.

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The present invention as it is defined in the character ^¬ izing clauses of .the claims, renders it possible to entirely eliminate the risk of contamination of the surr¬ oundings by asbestos, from the moment when asbestos is demolished in situ until it has been transported for final storage. Even in a later phase when the asbestos for some reason again is handled after its final stor¬ age, there is no risk of environment contamination.

The invention is described in greater detail in the following by way of example and with reference to the accompanying drawings, in which ^" Figs. 1 ^' and 2 show from the side and, respectively, from above an embodiment of an arrangement for carrying out the method according to the invention, and Pigs. 3-5 show from the side in two operation positions and, respectively, from above a second embodiment.

According to the invention, a space in the form of a container 1 is used, which is connected to a fan means, which with its suction side is connected upwardly via a connecting piece 2 (Pigs. 1 and 2) to said space 1. The space is divided into a gravity chamber 3 and a filter chamber 4. The gravity chamber 3 is separated by a partition wall 5 from the suction chamber 6, into which the connecting piece 2 opens, and two filters 7 are suspended on the continuation of the partition wall 5 in the filter chamber 4. A connecting piece 8 is provided to the gravity chamber 3 beneath the part¬ ition wall 5j and a hose (not shown) can be connected to the connecting piece 8. The free end of the hose can be formed as a nozzle, collecting cup, brush or the like, which is intended in situ, directly at the demol¬ ishing and decontamination of the asbestos to suck in the asbestos together with the ambient air for being transported to said space, the free end with the nozzle

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or the like can be handled easily by the workers and be suspended or positioned in a suitable place for keeping the working area to the greatest possible extent free from dust. In the space 1 the asbestos is coarsely separated from the conveying air in the gravity chambera 3j in which heavy and large particles and pieces drop down to the bottom of the space 1. Particles of lighter weight and dust are sucked from the gravity chamber to the filter chamber 4, the filters 7 of which clean the air which flows out from the space 1 via the connecting piece 2, as stated. The asbestos, which during the transport through the hose has been broken down to small pieces and a more or less fine dust, thus, is collected on the bottom of the space 1.

Beneath the space -1 a screw conveyor 9 is located, the conveying screw of which preferably has progressive pitch. The bottom 10 of the space 1 is open to the con¬ veyor 9, into which, thus, the asbestos material drops down when the arrangement is in operation. At the same time as the material is transported by the screw to the right-hand end of the conveyor 9 ₅ in Fig. 1, the material is broken down additionally to smaller dimens¬ ions. 11 designates schematically the driving motor of the conveyor. Via a down pipe 12 at the right-band end of the conveyor 9 the asbestos material arrives at one end of a second, slightly upward inclined screw conveyor 13, which at the other end is provided with an outlet connecting piece 14. 15 designates a cement bin, which by a pipe 16 is connected to the down pipe 12, and 17 designates water nozzles opening into the conveyor 13 , the driving motor of which is designated by 18. Via a cover 19 a cement bag can be positioned in the cement bin 15.

In Figs. 3-5 an embodiment is shown, at which in princ¬ iple the conveyors 9 and 13 have been replaced by a scraping device in the form of a vertical plate 21 located in the space 1. Above the same the filter chamb- er 4 with filters 7 is located. The connecting piece 6 connected to a fan means sucks the asbestos material through the hose and connecting piece 8 into- the chamb¬ er or space 1, whereby the air is separated from the material in the filter 7. The scraping device, which has a width corresponding to the width- of the space 1, is located on that side where the hose is connected to and below the opening of the connecting piece 8. By means of a hydraulic piston means, for example, (in¬ dicated by 22), it is possible to move the plate 21 in the space 1 and thereby to move the asbestos material ahead of the plate away to the opposite side of the space. This side can be divided into a plurality of compartments or boxes 23, which are open to the space, and into which the material is pushed by the plate. At different positions of the plate 21 or, for example, in the final phase of the plate movement to the boxes 23, a suitable liquid substance, for example thermo- setting resin, is sprayed into the collected asbestos material, which finally arrives in the boxes. As the dust-like asbestos material will be whirled about due to the movement of the plate through the space and due to the suction effect of the fan means, it is suitable at the start of the plate movement to simultaneously automatically close the inlet to the filter 7 by means of a cover 24. This packing process is repeated until the boxes have been filled, whereafter these boxes, for example in the form of a cassette 25, can be removed from the space for being transported further and handled. It is easily understood that the liquid sprayed in is of such a type that the time for its hardening is adjust¬ ed to the desired handling. 26 designates the driving motor for the scraping device 21.

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The place where setting liquid is to be sprayed into the space or where during the transport the injection could be effected, of course, can be varied within the scope of the invention, depending on the configuration of the space, the packing device, the type of liquid a.s.o. The liquid can be setting in order to form solid constituents of the asbestos material, but the liquid also can be imagined to be of such a type as together with the mat¬ erial to form a tough or liquid mass. These manageable units obtained by the method, either in the form of solid parts, viscous or liquid bodies, of course, can be con¬ verted, for example, to pellets or briquets for being used as filler for different purposes. It also is possible to imagine re-use of the asbestos in a later phase.