SE464068B - PROCEDURE FOR CLIPPING THE LAYER MINERAL PIECES AND DEVICE FOR IMPLEMENTATION OF THE PROCEDURE - Google Patents

Abstract

In a method for cleaving laminated mineral blocks (1) along an interface between two laminae a fluid under pressure is fed to the mineral block to be cleft at at least one place (21) in the boundary region between said two laminae so as to make the fluid penetrating between the laminae and while pressing them apart propagate between the laminae until they are separated by a continuous crack.

Description

464 068 Mica slate is mined in large blocks, usually in open pits, and these blocks are given an easy-to-handle size and shape by, for example, sawing. The mineral pieces of mica slate are built up of substantially parallel layers of material arranged on top of each other. The mica shale is very hard, but it can be split along the interfaces between two layers during the formation of surfaces that are very pleasing to the eye. This results in a small-wave surface which is very decorative and gives different reflections and visual impressions depending on the light incident on it and at what angle the slate surface is viewed. This surface is colloquially called hoof surface.

The procedure for achieving such a so-called hoof surface has hitherto been as follows: By means of hand force, several metal wedges have been driven in at a mutual distance in the area between two layers and in a direction substantially parallel to these layers by means of swinging a sledgehammer or hammer. Since the layered mineral piece has a pronounced tendency to want to split along the interfaces between the two layers, the driving of the wedges causes a crack which propagates between the two layers in question and finally completely separates the two layers, so that two pieces of material are formed with each its desired hoof surface. A so-called hoof has been performed.

However, this approach presents a number of disadvantages, not least for the person who has to perform the work in question.

Namely, it is very force-consuming to hit the wedges in the slate block with a sledgehammer and the rest breaks must follow at relatively short intervals, which is why the effective working time per work shift is short. The sledgehammer against the wedges produces very loud and unpleasant sounds, which require hearing protection and if neglected to use can lead to hearing damage. Furthermore, with each stroke, a smaller cloud of quartz dust comes from the wedge drive point, and since the striking person keeps his head relatively close to this point, he cannot avoid inhaling a portion of this quartz dust. This in the long run affects the person's health in a negative way.

Another disadvantage of this splitting method is that the material waste becomes relatively large. Where the wedges have been driven in, there will be ugly marks on the formed dividing surfaces, so an edge portion of these later must be sawn off and thrown away. Through the use of the wedges, the torque arms also become very long when the crack has propagated relatively far into the piece of material, whereby the torque arms grow with the spread of the crack from. the wrapped wedge against the opposite end of the piece of material.

These long torque arms mean that the risk of cracking in the direction substantially perpendicular to the two layers is imminent, which is why every close piece of material experiences breakage in this direction and parts of or in some cases the entire desired slate must be thrown away.

It is also known to use wedge-driven, percussion tools for splitting the slate blocks, but it has been shown that these further increase the risk of recently discussed fractures, as the driven percussion tools cannot be handled with the force balance and feel that is possible. when wrapping wedges by hand.

Finally, GB, A, 1 377 597 discloses a device for splitting slate by supplying pressure fluid to a cracking instruction made between two layers. Here, an existing vacuum around the slate block is used to make the splitting forces more efficient. Furthermore, porous foam plastic is applied around the block to reduce the fluid flow laterally in the crack between the two layers in question. Here, however, only a reduction of the said fluid flow takes place to facilitate the splitting, but a relatively high pressure is still required to achieve the splitting and in practice this is a cut, so that no fine splitting surfaces occur, sought by the present invention. BRIEF DESCRIPTION OF THE INVENTION The object of the present invention is to overcome the above-mentioned disadvantages of splitting layered mineral pieces along an interface between two layers by providing a method and a device which enables a fully acceptable and effective from a work environment point of view. splitting while minimally causing material spills and still achieving the desired fine natural so-called claw surfaces.

This object is achieved according to the invention by a method and a device according to appended independent claims 1 and 9.

By supplying a pressure fluid to the mineral piece which is to be split at at least one place in the boundary area between said two layers, so that the fluid penetrates between the layers and during pressing them spread between the layers until they are separated by a continuous crack, it is possible to Avoid all the inconveniences associated with poor working environment. Neither the hearing nor the lung condition of the person performing the cleavage is compromised, as neither noise nor dust clouds occur during the cleavage. The person only has to monitor the function of the device used for splitting. Furthermore, the need for frequent rest breaks is eliminated, as the work is no longer physically burdensome for the person in question.

Due to the fact that the fluid penetrates between the layers and due to the fact that it needs space to spread out and press the two layers apart to gradually spread further and further in between the layers while displacing the crack front through the piece of material, no long torque arms arise. without the crack-forming force always attacking the two layers very close to the propagation front of the crack, therefore the risk of occurrence This By the inventive sealing of the 'mineral piece. with a for the fluid substantially of cracks and fractures in other directions becomes minimal. significantly reduces material waste. 464 068 impermeable means along the outer boundary walls of the mineral piece at the level of the transition between the two layers, the fluid is forced to spread along the interface between the two layers and cause the desired cracking.

In some cases it may be necessary, for example by means of a wedge, to apply a small cracking instruction before the pressure fluid is applied, but even in such a case the surface portion damaged by the wedge, which must be cut off, becomes considerably smaller than when striking a row of wedges for performing the cleavage. In some cases, cracking instructions can be dispensed with and material spills due to wedge marks can be completely eliminated.

It should be emphasized that the splitting according to the invention takes place by pressing two layers apart and not by cutting in a plane parallel to these layers. Such a cutting, which could take place mechanically, for example by sawing, or by supplying a fluid under a very high pressure, would not result in the desired fine, small-wave splitting or splitting surfaces.

The fluid advantageously consists of water and it is possible to supply the water under a surprisingly low pressure, for example of about two bar, and still achieve a fission, by the water finding its way through the mineral piece while pressing the two layers apart. The possibility of this low pressure means that the fluid flow is very gentle on the surfaces that occur on both sides if the crack formed and damage to these is avoided.

Additional advantages and advantageous features of the invention will be apparent from the following description and the appended dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS Hereinafter, an exemplary preferred embodiment of the device according to the invention and the method which can be carried out by it with reference to the accompanying drawings are described, in which: Fig. 1 is a perspective view illustrating the method used today for splitting layered mineral pieces, Fig. 2 is a perspective view of a preferred embodiment of the device according to the invention, Fig. 3 is an enlarged, cut side view of a detail of the device according to Fig. 2 in operating position, Fig. 4 is a perspective view obliquely from above of the device shown in Figs. Fig. 5 is a schematic, cut side view, which is intended to illustrate how a mineral piece is split according to. the invention by water propagation between two layers.

BRIEF DESCRIPTION OF PRIOR ART In Fig. 1, Fig. 1 schematically shows how a mica slate block is split or split into slices. The slate block 1 is usually first sawn in the direction substantially perpendicular to the extent of the different layers, so that it obtains substantially smooth boundary walls. The thickness of such blocks 1 is usually about 30 cm and such a block contains a large number of layers, for example about 50 pcs. Slate slabs with a thickness of about 10-40 mm are usually required, so multi-layer slabs should be split away from the slate block. gaining clarity only the boundary layer surfaces along which it In order not to occur obliquely In the figure, however, are to be split drawn. breaking forces on the block, it is necessary for the wedges 2 to be wound between two layers substantially at half the thickness of the block. Several wedges are punched at a mutual distance along at least one boundary wall of the block. The figure shows how two such wedges still remain in the block, while a wrapped wedge is removed to illustrate the harmful mark 3 that the wedges leave behind. Through the impact of the wedges, a crack 4 propagates along the interface between the two layers between which the wedges have been driven in. In this way a splitting of the slate block 1 takes place. When this splitting has taken place, the two obtained slate block parts can in turn be halved in thickness by driving wedges between two layers thereof.

The disadvantages of this cleavage method have been discussed in detail (OVBI). .

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION Fig. 2 shows in perspective in a simplified manner a preferred embodiment of the device according to the invention. The device has a support 5, which is built up of rollers 6 arranged at a distance, which are arranged to support a mineral block 1 which is to be split along the interface between two layers. The substrate 5 is supported via power means 7, in the form of hydraulic cylinders, by a frame 8 resting on the ground. By lengthening and shortening the hydraulic cylinders 7, the substrate can be raised or lowered.

Furthermore, the device comprises a framework 9, and in this case a second force member 10, also in the form of a hydraulic cylinder, is arranged to act between the framework 9 and a pressure plate 11 arranged at one end of the force member, to press the plate 11 against the mineral block. 1 at the top and thereby clamping and fixing the block between the pressure plate 11 and the rollers 6 of the substrate 5. In this way, the mineral block 1 can be held in place in a substantially fixed position during the splitting process. Preferably, however, the force means 10 allows a slight movement, of a few mm, of the mineral block in height by pressing back the pressure plate 11 during the fluid penetration of the mineral block 1 and thereby slightly separating the material block portions located on either side of the cleavage surface in question. 464 068 At the framework 9, two rulers 12 extending substantially parallel in a horizontal plane in the form of square beams are arranged movable in the directions towards and away from each other.

However, these rulers 12 are not movable in height. The movements of the rulers are taken care of by the needle framework 9 and the respective ruler-acting third force means 13, also these. in the form of hydraulic cylinders. The third force means 13 are preferably jointly actuated by a single command. On each surface of the ruler facing the other ruler, i.e. towards the mineral block 1, a sealing element in the form of a rubber strip 14 is attached (see especially Fig. 4). The rubber strip 14 here has the same width as the respective ruler 12, but it could be considerably narrower, in which case a very straight crack propagation can be expected, as it is only necessary that it abuts on both sides of the formed crack. With a narrower strip, the abutment pressure of the power members 13 could be reduced.

The device also has a plate 15 arranged to be pressed against a boundary wall of the mineral block substantially perpendicular to the direction of extension of the rulers. For this purpose, a fourth force member 16 in the form of a hydraulic cylinder is arranged to act between a part 18 otherwise fixable via rigging screws 17 relative to the frame 17 and the plate 15. The surface of the plate 15 facing the mineral block 1 is provided with a nozzle 19 (see also Fig. 4), which consists of a substantially horizontally extending rubber strip 20 with an opening 21. To the opening 21 of the nozzle 19 a pressure fluid line in the form of a water hose 22 is passed through the plate 15. Its end is indicated in Fig. 3.

The unit for supplying the water through the line 22 is not shown in the figures, and this can be designed in any manner known per se.

The rubber strip 20 is arranged to extend along the entire width of the x-mineral block all the way to the rubber strips of the two rulers, so that the rubber strips 14 and 20 are capable of except for the opening. 21 form a watertight boundary of the mineral block 1 along three boundary walls of the mineral block over a surface which in height corresponds to the width of the strips.

By adjusting the rigging screws 17, it can be ensured that the rubber strips 14 tightly connect to the rubber strip 20. In Fig. 4 it is shown how the plate 15 with the strip 20 is inserted between the rulers 12, but to adapt the device to mineral blocks with different widths, the rulers 12 may be arranged not to slide past the end edge of the block and the length of the strip 20 is increased to an appropriate degree.

The operation of the device according to the invention described above will now be described with reference also to Figs. 3-5. A mineral block to be split along the interface between two layers, possibly in several places to divide the mineral block into several slices, is first cut so as to obtain smooth side boundary walls, in the manner shown in Fig. 2. This block is then laid on it by the substrate 6 formed the substrate and the second force member 10 is actuated to fix the mineral block relative to the substrate 5. Thereafter the force means 7 are actuated so that the substrate 5 is moved vertically relative to the rulers and nozzle 19 provided with the rubber strips 14. which a first interface along which it is to be split lies in a horizontal plane approximately midway between the upper and lower edges of the rubber strips 14. When this position is reached, the third force means 13 are operated to bring the rulers 12 against each other, so that the rubber strips 14 come into sealing abutment against two layers of the mineral block on either side of the transition therebetween. Thereafter, the fourth force means 16 is actuated to press the nozzle 19 into a sealing abutment against the mineral block on either side of the same layer transition. It is possible to provide the mineral block with a small cracking guide 24 at the place which is intended to be located opposite the opening 21 of the nozzle. Such cracking instructions 24 are illustrated in Fig. 3 and assist in the initiation of the desired fissure crack. In this figure, for the top plate to be split, all the layers are shown from the mineral block, while otherwise only the boundary layer surfaces along which it is to be split are indicated. Thereafter, water is supplied under relatively low pressure (experiments have shown that pressures below 2 bar are sufficient in some cases) to the opening 21. However, to initiate crack formation, higher pressures, such as about 10 bar, may be required. The water penetrates into the cracking guide 24 and is prevented by the rubber strips 20 and 14 from escaping from the mineral block. The water will therefore exert forces in the direction substantially perpendicular to the plane of the two layers and push the two layers apart over and over again during propagation of a crack which is rapidly filled by the water towards the opposite opening 21 of the mineral block 1. How this takes place is illustrated in Fig. 5. The torque arms during this squeezing consequently become very short, as the water constantly fills the formed crack and exerts squeezing forces in the area of the crack front present at any moment. Therefore, the risk of unfortunate crimes is very small. Thanks to the short ones. the moment arms, it is also possible to split the mineral block in the desired place, ie also so that the mineral block parts lying on either side of the formed crack have considerably different thicknesses.

When said crack propagated along. the entire interface in question and thus the splitting is completed, the water supply to the nozzle 19 is interrupted and the force means 16 and 13 are operated to remove the sealing strips from the mineral block 1.

Thereafter, the force means 7 is actuated to move in height the substrate 5 and thus the mineral block 1 to a position which is suitable for carrying out the next splitting, whereupon the working steps described above are repeated to achieve the same. In this way it is possible to start, for example, 30 mm from the top of the mineral block with a split along the interface between two layers and then the mineral block is gradually moved upwards while splitting thin slices from the lower part of the mineral block until the block consists only of such thin slices. The invention is of course not in any way limited to the preferred embodiment described above, but a number of possibilities for modifications thereof should be obvious to a person skilled in the art, without this departing from the basic idea of the invention.

For example, it would be possible to supply fluid other than water for cleaving the mineral block, for example some other liquid or even a gas under a certain overpressure. In this case, however, it should be borne in mind that the pressure of the supplied fluid must be so low that the cleavage takes place by pressing the two layers apart and not by a cut along a plane in the interface between the layers.

It would also be possible to arrange sealing elements at the end 25 of the mineral block, so that the mineral block is sealed substantially all around, but then it would be necessary to arrange some form of escape openings for the fluid in the vicinity of this end.

Of course, the block to be split by the device could be in completely different shapes than the one shown in the figures, the device then receiving corresponding changes. However, it is advantageous for the material block to have smooth boundary walls, but this is not absolutely necessary, but it would also be conceivable to arrange some other type of sealing element, for instance some form of sealing mass sprayable along the mineral block.

Furthermore, it would be conceivable to provide some other type of means than sealing elements to prevent the fluid from escaping from the mineral piece at its outer boundary walls before the continuous crack is formed.

It would also be possible to supply the fluid at several places along the periphery of the mineral block, and the supply of the fluid at a short side of the mineral block, as shown in Fig. 2, should by no means be considered limiting of the invention, but the supply point or places may be preferably be located on a larger side of the block.

The above pressure indications for the fluid are to be considered as examples only and do not constitute limits of the invention.

Claims (16)

ß 464 068 Patent claim A method of cleaving layered mineral pieces (1) along an interface between two layers by using a pressure fluid, the pressure fluid being supplied to the mineral piece to be cleaved at at least one place (24) in the boundary area between said two layers, characterized therefrom , during the supply of the fluid this is prevented from escaping from the mineral piece at its outer boundary walls (23) before a layer separating, cohesive crack is formed by sealing the mineral piece with a means (14, 20) substantially impermeable to the fluid along the outer boundary walls of the mineral piece with the transition to the two layers, in order for the fluid to penetrate between the layers and, during their pressing apart, spread between the layers until they are separated by said continuous crack. Method according to claim 1, characterized in that before the fluid supply the mineral piece is cut in planes with a substantial angle, preferably right angle, to the layer plan for the purpose of giving the mineral piece outer boundary walls with smooth surfaces to facilitate the application of the sealant (14, 20) . 3. A method according to claim 2, characterized in that the sealing is effected by pressing substantially flat pieces of material (14, 20) into abutment against the two layers on either side of the transition therebetween along at least the main part of the boundary walls of the mineral piece. 4. A method according to any one of the preceding claims, characterized in that the fluid supplied is a liquid. 5. A method according to claim 4, characterized in that it is water which is supplied to the mineral piece. 464 us' ” 6. A method according to claim 4 or 5, characterized in that the liquid is supplied with a low pressure, preferably between 1.5 and 2.5 bar. A method according to any one of the preceding claims, characterized in that the linear piece to be split consists of mica slate. 8. A method according to any one of the preceding claims, characterized in that before the fluid supply the mineral piece is provided with a cracking instruction (24) at said place or places for fluid supply. Device for cleaving layered mineral pieces along an interface between two layers by using a pressure fluid, comprising means (22) for supplying the pressure fluid at at least one place (21) in the boundary area between said two layers, characterized thereof, that it comprises means (14, 20) for preventing the fluid from escaping from the mineral piece (1) (23), and that said means comprise one or more elements (14, 20) which are substantially impermeable to the fluid and which are arranged to seal the mineral piece along its outer boundary walls at its outer boundary walls at the height of the transition between the two layers. Device according to claim 9, characterized in that the elements consist of substantially flat pieces of material (14, 20), and that the device comprises a force device (13, 16) arranged to press the flat pieces of material into abutment against the two layers on each other. sides of the transition therebetween along at least the main part of the boundary walls of the mineral piece. Device according to claim 10, characterized in that the piece of material (20) intended for abutment in the area of the site of the fluid supply has an opening (21), said means comprising a fluid line (22) arranged to ) 464,068 mouth in this opening, and that the portions of the piece of material surrounding the opening are arranged to connect tightly to the periphery of the fluid line. Device according to claim 10 or 11, characterized in that the pieces of material (14, 20) consist of flat rubber plates or strips. Device according to one of Claims 9 to 12, characterized in that it comprises a device (7) arranged, after the cleavage of the mineral piece (1) along a interface between two layers, to bring about a relative displacement of the mineral piece. (1) and the fluid supply point (21) in a direction substantially perpendicular to the plane of extension of the layers for the purpose of moving the point of supply of pressure fluid to a boundary area between another pair of layers in order to perform several fissures of one and the same mineral piece. Device according to claims 10 and 13, characterized in that it comprises a substrate (5) on which the mineral piece (1) is intended to rest with the layer plane substantially parallel to the fact that the power device (13, 16) is arranged to after a completed cleavage along the interface between two layers, the sealing material pieces (14, 20) are removed from the mineral piece, and that said relative displacement device (7) is arranged to after this removal effect a relative movement in height between on one side the substrate (5) and on the other hand, the sealing pieces of material (14, 20) and the fluid supply point (21) for bringing the pieces of material and the fluid supply point into position for splitting the mineral piece along an interface between another layer pair of the mineral piece. Device according to any one of claims 9-14, characterized in that the supply means (22) is arranged to supply a liquid to the boundary area between the two layers. M 464 068 Device according to claim 15, characterized in that the liquid is water, and that the supply means is arranged to supply the water under a low pressure, preferably between 1.5 and 2.5 bar.