NL1017770C2 - Apparatus for separating asbestos and soil comprises shaking sieve and sprayer for adding liquid with high-pressure spray head - Google Patents

Abstract

An apparatus for separating asbestos and soil comprises a shaking sieve and a sprayer for adding a liquid with a high-pressure spray head(s) that produces a stream of liquid in a given direction and is at a given height above the material being treated.

Description

Short description: Asbestos cleaning.

The invention relates to a device for separating asbestos material and soil from each other, comprising a shaking sieve and means for supplying liquid arranged above the shaking sieve.

The invention also relates to a method for separating asbestos material from soil.

Such a device and method are known from U.S. Pat. No. 5,421,527. Described therein is an apparatus in which soil contaminated with asbestos is passed over a shaking sieve with spraying means arranged at the shaking sieve for supplying liquid. If the debris on the shaking sieve is sufficiently small in size, they fall through the shaking sieve, otherwise they are transported to a collecting bin.

Material that ends up in the receiving bin is pulverized in a device intended for this purpose, after which the pulverized material is again passed over the shaking sieve.

In many past years buildings and installations have been demolished and the demolition material has been used, among other things, as filling material and / or paving in soil. For example, land in or under roads and paths in (not yet) urbanized areas. In many cases, such a demolition material also contained asbestos, in particular tightly bonded asbestos. Tightly bonded asbestos material means that the material consists of asbestos-cement products, as opposed to loose-bonded asbestos products such as spray asbestos and insulation materials.

In places where such demolition material including bonded asbestos has entered the soil, the relevant bonded asbestos material 30 must be removed from that soil according to current standards. The removal should preferably be such that as much as possible of the soil removed from the soil with tightly bonded asbestos material in it is removed again after removal of the tightly bonded asbestos material at the location where the soil in question has been removed from the soil or at another location. location where asbestos-cleaned soil is necessary. After removal of tightly bound asbestos material, in the Netherlands _ 1017770 2 means less than 10 milligrams of asbestos per kilogram of soil. In many places where tightly bound asbestos material is present in the soil, the soil in question is clayy. Clay has the property of being highly cohesive, making it difficult to remove clay from pieces of tightly bonded asbestos material in such a way that sufficient asbestos-free clay is recovered without exceeding the aforementioned lower limit of 10 milligrams of asbestos per kilogram of soil.

It has been found that the rinsing as described in US Pat. No. 5,421,527 is unable to remove clay to a sufficient extent from tightly bonded asbestos material. The device as described in US patent 5,421,527 is furthermore unsuitable for separating tightly bound asbestos material and soil precisely because the device in question is provided with a device which pulverizes larger debris. On the contrary, this leads to an increase in the smaller pieces of bonded asbestos that are increasingly difficult to remove from the soil where they are located.

The object of the invention is to provide a device and a method in which tightly bonded asbestos material can be stripped of soil adhering to it, in particular clay, in such a way that the relevant remaining soil is less than the above-mentioned limit of 10 milligrams of asbestos per kilogram of soil. and the debris of tightly bonded asbestos are sufficiently stripped of soil adhering to it. It is also an object of the invention to provide such a device and method that the separation of asbestos material and soil from each other can take place in a sufficiently economic manner both in terms of costs and in terms of speed. It is a further object of the invention to provide a method for separating soil and tightly bonded asbestos material without the addition of chemical agents.

A device according to the invention is for this purpose characterized in that the spraying means for supplying liquid comprise at least one high-pressure spraying head belonging to a high-pressure liquid-spraying installation, which high-pressure spraying head, when in operation, delivers a bound jet which, after a certain distance, changes into a broken jet, in that the high-pressure liquid spraying installation is arranged for the high-frequency jet emitted by the at least one high-pressure spraying nozzle to run through a more or less closed path, and in that the device operates the distance between the at least one high-pressure spraying head and material on the shaking sieve 5 is substantially equal to the distance over which the jet delivered by the at least one high-pressure spray head is bound.

For the purposes of this invention, high pressure is to be understood to mean that the pressure at which the liquid is supplied to the high-pressure spray head is higher than 250 bar or that the pump power of the pump 10 supplying the liquid to the high-pressure spray head has a power of more than 10 kW at a pressure higher than 25 bar.

It has been found that the jet which jets from the high-pressure spray head must be a so-called bound jet. This means that the jet does not immediately begin to spray when the high-pressure spray head comes out and starts to break up into separate droplets. As long as the jet emerging from the high-pressure spray head is bonded, in an installation according to the invention, the jet will have an effective cleaning effect on the asbestos cement material.

It has been found that at a distance between the high-pressure spray head and the material on the shaking screen which is considerably larger than the distance over which the jet delivered by the at least one high-pressure spray head is bound, it is no longer possible to move within an economically acceptable periodically remove debris of asbestos cement material from soil adhering to it, in particular clayey soil.

A preferred device according to the invention is characterized in that the device comprises two or more high-pressure spray heads and in that the pathways traversed by the jets do not intersect each other.

As a result, it is achieved that a number of heads can be placed next to each other, so that the path over which the device separates soil and asbestos material has a considerable width. It has also been achieved that the jets coming from the high-pressure nozzles do not interfere with each other, so that their effectiveness would be largely or completely lost.

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A further preferred device according to the invention is characterized in that, viewed in the flow direction of the shaking screen, the trajectories traversed by the jets are at least partially mutually exclusive.

It is thus achieved that, without there being a risk of the jets intersecting each other, there is nevertheless the certainty that each part of asbestos material that is passed over the shaking sieve is actually reached by a jet from a high-pressure spray head.

A further preferred embodiment of a device 10 according to the invention is characterized in that the traversed path is substantially circular.

As a result, it is achieved that commercially available high-pressure nozzles can be used which cause a liquid jet circulating over a conical surface.

A further preferred embodiment of a device according to the invention is characterized in that the amount of liquid supplied by the at least one high-pressure spray head per unit time is sufficient for discharging loosely sprayed soil with the amount of liquid supplied per unit of time.

As a result, it is achieved that the same liquid that is used for pulverizing the soil on the asbestos material also serves as a discharge means for the pulverized soil. As a result of this it is also achieved that the pulverized soil does not get in the way of the jet when it comes along the next time it runs through the more or less closed path, which would reduce the effectiveness of the jet.

A method according to the invention is characterized by passing tightly bonded asbestos material with soil adhering to it over a shaking sieve and directing at least one bonded jet of liquid onto the tightly bonded asbestos material with ground adhered to it from such a distance with the aid of a high-pressure liquid spraying installation the bound jet breaks up mainly in the vicinity of the tightly bound asbestos material with soil adhering to it and by passing the bound jet 35 through a more or less closed path over the shaking sieve 1017770 ...

5 bonded asbestos material with soil adhering to it.

As a result, it is achieved that the soil is pulverized by the breaking radius, while the tightly bound asbestos material is not affected, or is sufficiently affected, by the radius in question. To a sufficiently small extent in this case means that any loose asbestos from the asbestos cement material in the pulverized soil carried with the liquid yields an amount of less than 10 milligrams per kilogram of soil.

A preferred embodiment of a method according to the invention is characterized in that prior to passing the tightly bonded asbestos material with soil trapped thereon over the shaking sieve, the soil that is attached to the tightly bonded asbestos material is at least partially soaked with liquid.

As a result, it is achieved that the mutual adhesion of the particles forming the soil is weakened, so that the breaking-up jet sprays the soil of the adhesively bonded asbestos material more easily, and therefore faster.

The invention will now be explained in more detail with reference to the accompanying drawings, in which:

Figure 1 is a longitudinal section of a device according to the invention;

Figure 2 is a cross-section of a device according to the invention along the line AA in Figure 1; Figure 3 shows a top view of the shaking sieve with the trajectories traversed by the different rays projected thereon;

Figure 4 is the same view as Figure 3 of a second embodiment of the device; Figure 5 is the same view as in Figure 3 of a third embodiment of the device;

Figure 6 schematically represents a footprint of a jet;

Figure 7 is a representation of a high-pressure spray head with an exiting bound jet.

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In figure 1 reference numeral 50 indicates a device which comprises a more or less elongated tray 1 with an entrance side 2 and an exit side 3 and a bottom exit 4. In the longitudinal direction of the elongated tray 1 is a per se known shaking screen with seven 5, 6 and 7. Material that falls through the seven 5, 6 and 7 ends up in a container 8 via the outlet 4. Material that does not fall through the seven 5, 6 and 7 finally ends up in a container 9. The seven 5, 6 and 7 move back and forth in the direction of the arrow B. Reference numeral 10 denotes a conveyor belt with which 10 debris 11 consisting of rubble granulate and asbestos cement on which soil is stuck are supplied and fed into the opening 2 on an inclined surface 12 from which the debris, indicated by reference numeral 13, reach the shaking screen 5. With reference to figure 2, an installation 14 is placed near the device 50, whether or not displaceable, for bringing liquid under high pressure. In general, but not necessarily in connection with the present invention, the liquid will be water. Reference numeral 15 indicates a control panel with which the pressure and / or the flow rate of the liquid to a high-pressure liquid spraying installation 16 can be regulated. In the exemplary embodiment shown in Figs. 1 and 2, the high-pressure liquid spraying installation 16 comprises five high-pressure spraying heads 17, 18, 19, 20 and 21. A connecting tube 22 connects the device 14 to the device 16. High-pressure is understood to mean a pressure higher than 250 bar or when the pump power of the device 14 is more than 10 kW, a pressure higher than 25 bar. The high-pressure spray nozzles 17, ..., 21 each provide a directed jet of liquid with the direction of the jet moving more or less over a conical surface. Such nozzles are known per se and commercially available, for example under the designation Monro-Jet 30 from Salotech in Oud-Beijerland. A Monro-Jet high-pressure nozzle has an outlet opening with a diameter of 1.35 mm and delivers a jet which is forced through the outlet opening at a speed of approximately 450 m / s. The jet then remains a bound jet over a distance of about 40 cm before the jet breaks into 35 smaller droplets and nebulizes. In order to cover the entire width of the shaking sieves 5, 6 and 7, the high-pressure spray nozzles 1017770 7 17, ..., 21 are placed at a mutual distance of approximately 15 cm. The conical surface around which the jet circulates, and whose footprint is shown in Figure 6, has an apex angle of approximately 10 °. In Fig. 6, reference numeral 23 denotes a current footprint of a radius, while reference numeral 24 indicates the path covered by the footprint 23 once the radius goes round, for example in the direction of the arrow C, but it can also be in one direction are opposite to arrow C.

The operation of the device 50 is as follows. The liquid is pressurized with the aid of the device 14 and supplied via the connecting tube 22 to the high-pressure liquid spraying installation 16. As a result of the liquid being supplied to the installation 16 under pressure, the high-pressure spraying nozzles 17-21 each go a jet dispensing liquid from the outflow opening, which liquid-jets describe cone surfaces of which a footprint is shown in figure 6. The frequency with which the footprint 23 traverses the path 24 is generally in the order of a few kHz, depending on the pressure generated by the device 14 as well as the amount of liquid which is supplied by the device 14 per unit of time via connecting hose 22 to the installation 16 and to the high pressure nozzles 17-21.

The aforementioned Monro-Jet causes the jet to rotate at a frequency of approximately 8 kHz if the liquid is water and is supplied at a pressure of 1000 bar and a flow rate of approximately 35 liters per minute.

Fragments of asbestos cement with soil adhering to them, in particular clay, are supplied to the device 50 via the conveyor belt 10 and end up as fragments 13 on the shaking sieve 5. The shaking sieves 5, 6 and 7 move back and forth in the direction of the arrow B 30 with a frequency of approximately 1 to a few hZ. Due to the sloping screens 5, 6 and 7, a block 13 moves slowly but surely from the plate 12 in the direction of the high-pressure liquid spraying installation 16 and the conical circular jets 25, 26, 27, 28 and 29 generated thereby.

Figure 7 shows, by way of example, nozzle 17 with the jet 25 exiting therefrom. As is shown in Figure 7 with arrow - 1017770 8 E, the jet 25 moves over a conical surface. Arrow D indicates the distance over which the beam 25 remains bound. At a pressure of 1000 bar and a flow rate of approximately 35 liters per minute, the distance D is approximately 35 cm with a nozzle of the aforementioned type of Monro-Jet.

In figure 2 arrow F indicates a distance between the exit openings of the nozzles 17-21 and the shaking screen 5 of approximately 40 cm. As a result, when a Monro-Jet high-pressure spray head 17-21 is used, the bound jets 25-29 begin to break up at 10 near the asbestos-cement debris 13 with soil adhering to it.

It has also been found that the amount of liquid, in the above-mentioned examples about 35 liters of liquid per minute per nozzle, is sufficient and must also be sufficient to drain the pulverized soil 15 from the debris pieces 13 and, together with the liquid, into outlet 4. container 8.

Figure 3 shows a series of footprints of high-pressure spray heads 17-21 as it could be "visible" via a section G-G (see Figure 2). Each of the footprints consists of the fact that a cross-section of the jet in figure 3 indicated by reference numeral 30 makes a circular movement. In the examples shown above, a diameter of the footprint 30 of the radius is of the order of 4 to 5 mm and a diameter of a circle 31 is approximately 15 cm. The arrow H in Figure 3 indicates the direction of movement of blocks 13 relative to the footprints 31, 32, 33, 34 and 35 of the rays 25, 26, 27, 28 and 29, respectively.

In view of the extremely high velocities in the outflow openings of the high-pressure nozzles, of the order of 450 m / s in the examples shown above, two jets which touch each other will give rise to a complete disruption of each of the jets and a loss of the effect according to the invention. To this end, with an arrangement as shown in Fig. 3, great care must be taken with regard to the precise adjustment of the high-pressure nozzles with respect to each other and with respect to the walls 36 and 37 of the device 1.

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In figure 4 it is shown that for the protection of the walls 36 and 37, conductors 38 and 39 can be used which ensure that debris 13 moving in the direction of the arrow H is not in a no man's land 40 or 41 between one of the 5 outer cones 31 and 35 and the adjacent wall 35 or 37 can end up.

Figure 5 shows an improved embodiment of the device shown in Figure 4. In Fig. 5, the debris 13 again moves in the direction of the arrow H and is guided by the guides 38 and 39 to within the range of the outer footprints 31 and 35. The high-pressure liquid spraying installation 16 again comprises five high-pressure spraying heads which, however, not all five are placed on one line but on two different lines. It is clear from the footprints 31-35 in Figure 5 that the rays which generate those footprints cannot come into contact with each other, while in the direction of the arrow H every movement will always encounter at least one of the footprints 31-35. As a result, the entire width of the device 1 between the conductor boards 38 and 39 is covered with a jet from a high-pressure spray head.

Although in the foregoing an apparatus has been shown by way of example with five high-pressure spray heads, the number of high-pressure spray heads can be both larger and smaller. Jets circulating over conical surfaces are commercially available with high-pressure nozzles. However, the invention is not limited thereto, also nozzles that generate footprints other than circular, provided that they are generated with the aid of a jet following a certain path, are applicable to the present invention. The Monro-Jet mentioned as an example is not the only commercially available high-pressure spray head which supplies a jet circulating over a conical surface, other types are also commercially available and can be used in the invention. The only condition is that the high-pressure spray head supplies a jet which remains bound over a certain distance after leaving the outlet opening of the spray head and then begins to break up into separate droplets.

Although the invention can be applied to many types of soil, application of the invention to adhesively bonded asbestos to which chunks of clay adhere is particularly advantageous with respect to known solutions.

In order to speed up the process as it takes place in a device according to the invention, prior to passing the tightly bonded asbestos material with soil adhering to it over the shaking sieves 5, 6 and 7, the soil that is attached to the tightly bonded asbestos material may be at least partially soaked with liquid. To that end, the chunks of tightly bound asbestos material with soil adhering to it can be soaked in advance in a vessel 42 with liquid 43 before being supplied to the device 1 by means of the conveyor belt 10.

With other types of high-pressure spray head, the bound jet will generally remain bound by a different distance than mentioned above before breaking into separate drops. Also at that point the pressure exerted on the liquid with the aid of the device 14 as well as the amount of liquid supplied per unit of time from the outflow opening by a high-pressure spray head and depending on the device 14 may or may not be known per se in a manner known per se. is adjustable with the aid of control panel 15. Often the outflow opening of known high-pressure nozzles is circular with a diameter of between 0.5 and 3 mm.

Also, the apex angle of the cone, in the case of circular footprints, will not be approximately 10 ° for each high-pressure nozzle, but that apex angle can depend on the type of high-pressure nozzle a value between 1 and 179 °. In practice, the apex angle will be between 5 and 25 °.

After the foregoing, various embodiments and modifications will be obvious to those skilled in the art. All such modifications and changes are considered to belong to the invention.

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Claims (13)

Device for separating asbestos material and soil from each other, comprising a shaking sieve and spraying means for supplying liquid arranged at the shaking sieve, characterized in that the spraying means for supplying liquid comprise at least one high-pressure spray head belonging to a high-pressure liquid spray installation, which high-pressure spray head, when in operation, delivers a bound jet which, after a certain distance, changes into a broken jet, that the high-pressure liquid spray installation is adapted to pass through the high-frequency jet delivered by the at least one high-pressure spray head a more or less closed path and that when the device is in operation the distance between the at least one high-pressure spray head and material present on the shaking sieve is substantially equal to the distance over which the jet emitted by the at least one high-pressure spray head is bound . Device as claimed in claim 1, characterized in that the device comprises two or more high-pressure spray heads and that the pathways traversed by the jets do not intersect each other. 3. Device as claimed in claim 2, characterized in that, viewed in the direction of travel of the shaking screen, the trajectories run through the jets at least partially overlap each other. Device as claimed in any of the foregoing claims, characterized in that the traversed path is substantially circular. Device as claimed in any of the foregoing claims, characterized in that the distance between the at least one high-pressure spray head and the shaking sieve is adjustable. 6. Device as claimed in any of the foregoing claims, characterized in that the speed with which the jet passes through an outflow opening of the at least one high-pressure spray head is greater than 300 meters per second. Device according to claim 6, characterized in that the outflow opening is more or less circular and has a diameter greater than 0.5 mm. - 1017770 Device as claimed in claim 6 or 7, characterized in that the outflow opening is more or less circular and has a diameter of less than 3 mm. 9. Device as claimed in any of the foregoing claims, characterized in that the quantity of liquid supplied by the at least one high-pressure spray head per unit of time is sufficient for discharging loosely sprayed soil with the aid of that quantity of liquid supplied per unit of time. Device as claimed in any of the foregoing claims, characterized in that the high-pressure liquid spraying installation is adapted to control the pressure on the liquid supplied to the high-pressure spraying head and / or of the quantity of liquid supplied per unit time by the high-pressure spraying head. 11. Method for separating asbestos material and soil, characterized by passing tightly bonded asbestos material with soil stuck thereon over a shaking sieve and directing at least one bound jet of liquid onto the tightly bound asbestos material with stuck on it by means of a high-pressure liquid spraying installation soil from such a distance that the bonded beam breaks up mainly in the vicinity of the bonded asbestos material with soil adhered to it and by passing the bonded beam through a more or less closed path over the bonded asbestos material on the shaking screen with bonded thereon ground. A method according to claim 11, characterized in that each point of the tightly bound asbestos material carried over the shaking sieve with soil adhering to it crosses the at least one pathway at least once. 13. A method according to claim 11 or 12, characterized in that prior to passing the tightly bonded asbestos material with soil adhered to it over the shaking sieve, the soil that is attached to the tightly bonded asbestos material is at least partially soaked with liquid. 1017770