EP0136523B1 - Process and device for pneumatic output of hydromechanically transported hydraulic building material in underground mining - Google Patents

Description

The invention relates to a method for the pneumatic application of hydromechanically promoted hydraulic building material for underground operations according to the preamble of claim 1. The invention also relates to a device for carrying out this method.

Hydraulic building materials, which are used underground, are granular to powdery substances with different water-solid factors, which are often sprayed with additives, e.g. made of plastic or fiber mixtures. The invention relates in particular to shotcrete from these building materials or mortars, which in turn are applied as early as possible after the excavation has been extracted, for example by blasting, in several centimeters of thickness on the rock shell of mine structures, in particular from sections with a recess in the base. to increase the self-bearing capacity of the surrounding mountains. In addition to this protection against breakouts when opening rooms in mining and tunnel construction, the method according to the invention also serves to seal fire and weather insulation and to smooth walls with the aim of reducing weather resistance, and generally for sheeting work. With the aim of early strength, preferably liquid excitation agents can be added to the building material in order to ensure an optimal load-bearing capacity after a short time. keeps the convergence of the mountain strata low.

The hydromechanical conveying of the wet building material, in particular in the form of a mortar or concrete, has the advantage over the known dry conveying, in which the necessary mixing water and possibly a stimulator are added to the building material at the end of the line, the advantage of a uniform composition of the applied layers according to a predetermined Recipe that eliminates the fluctuations in strength in the applied layers due to the uneven composition of the building material and the uncontrolled addition of water. The invention is therefore based on a previously known method (BE-A-855 720), in which the building material is discharged with the aid of a nozzle provided with a nozzle of a delivery pipe or hose line to which a pump is applied and is sprayed onto the surface to be coated.

In the known device, the building material is conveyed hydromechanically in the axial direction of the nozzle. Shortly before the nozzle, compressed air is added to the hydromechanical delivery flow via nozzle channels arranged radially in the mouthpiece. However, there are limits to the acceleration of the building material. Because the nozzle device must take into account the limited compressibility of the wet building material because of the risk of clogging. The building material is guided in direct contact past the mouths of the compressed air channels, so that the compressed air flow sees a relatively smooth and therefore small contact surface at this point. An effective cutting of the building material is hardly possible. Furthermore, there is a risk of the compressed air supply lines becoming blocked, which leads to total failure of the method or of the device.

The hydromechanical conveyance of the building material makes it more difficult if the building material for reasons of reduced friction in the delivery line, it is brought into it with a comparatively large cross section and it is not possible for a plurality of discharge pipes or hoses to be fed in simultaneously through a distributor. Because in these cases, the hydromechanical flow, as in another known device, must also be reduced to a smaller cross-section on the mouthpiece, which results from the handling of the mouthpiece with the required forces of an operator, unless manipulators or monitors can be used.

Because irrespective of these difficulties because of the danger of impairment of the ways of hydromechanical conveying through hardening building material, the exciter either only wants to add at the last moment or, as provided in BE-A-855 720, directly add with the compressed air flow, this happens with one or more nozzles at the end or shortly before the end of the hydromechanical conveyor line. However, this means that the exciter does not mix completely and not homogeneously with the hydraulic building material. Then the layers produced are inhomogeneous, in which the required early strength is not achieved everywhere. There is also the fact that losses of excitation liquid occur which are carried along with the radially guided propellant air and lead to pollutant concentrations in the atmosphere.

From this, but also from other causes, rebound losses can occur, which means the percentage of discharged building material that is not liable and falls down. Although the usual 30% to 40% ranges for dry processes are not achieved by wet processes, their quota also has different causes. It depends, among other things, on the adhesion of the building material, the angle of incidence of the building material jet emerging from the mouthpiece and the like. Parameters. In particular, however, the system-related changes in the load-bearing capacity of the substrate that the building material strikes during spraying represent one of the main causes of the rebound. Because regardless of the hardness of the impact, eg. B. a mountain surface changes Resistance of the substrate in the course of the build-up of the spray layer and usually gets lower the more the job grows. The early strength of the building material therefore plays a role in this context, as does the amount of building material that is discharged. However, the known device does not allow the impact speed to be controlled and the exciter to be used to avoid excessive rebound losses, but in any case not to the extent necessary.

The invention has for its object to perform the known as a method so that it can be mastered better and in particular offers the possibility of using the exciters to achieve better economy while protecting the atmosphere and effectiveness in the applied layer, the new processes should also create the conditions for reducing system-related rebound losses.

The invention solves this problem with the features of claim 1. Appropriate embodiments of the invention are the subject of the dependent claims.

In the method according to the invention, the building material is fed into a conveying air flow in such a way that the dense flow of the building material is broken up and the resulting building material particles are accelerated in such a way that they remain in suspension in the conveying air flow. This the building material in a. Conveying air flow containing density dependent on the air speed and volume on the one hand and the flow rate on the other hand can be discharged from the mouthpiece without the risk of clogging and, in the case of nozzle-shaped mouthpieces, can also be constricted and therefore discharged at an increased speed, which for a given cross section and given delivery volume essentially depends on the compressed air quantity is dependent. On the other hand, breaking up the dense flow, in which the building material is conveyed hydromechanically, leads to an increase in the free building material areas, which in turn offer favorable conditions for improving the absorption of any exciter used.

The invention therefore has the advantage that it leads to a substantial reduction in the weights to be manipulated at the mouthpiece and brings out the building material in a loosened state, which favors a uniform distribution of the building material on the respective subsurface and thereby already leads to a considerable reduction in the rebound losses leads. Breaking up the dense stream with the aid of the compressed air stream has no disadvantageous consequences for the building material, because this process, as far as it leads to separation of the building material, is reversed on impact. Air consumption is kept within tolerable limits because the pneumatic conveying path created is limited to the mouthpiece and is relatively short.

To further increase the effectiveness of the method, the exciter is already distributed in the compressed air stream, in particular atomized in it.

This increases the number of excitation particles and the likelihood that an excitation particle will meet with a building material particle due to the relative speed of these particles when the dense stream is added. With a considerably reduced amount of excitation, a considerably improved effect of the exciter is achieved at the same time, which is swirled together with the compressed air flow before it hits the dense flow. The swirling of the compressed air flow can also contribute to increasing the density of the building material in the conveying air flow and thereby reducing the amount of compressed air that is required for the application of the building material.

With the features of claim 2, the rebound losses can be reduced, which have so far increased disproportionately due to the system with increasing layer thickness. By reducing the flow of conveying air, the pump used for hydromechanical conveying, which is usually designed as a piston pump, less often as a screw pump, can work evenly with the specified application quantity, but the quantity and speed of the building material contained in the impinging spray jet can still be adjusted. The realization of the features of claim 3 offers the advantageous possibility of appropriately accelerating the building material emerging from the end of the hydromechanical conveying line from its relatively low speed to the considerably higher pneumatic conveying speed and preventing building material sedimentation.

The effect of one or more admixtures in the conveyed concrete presupposes an exposure time of different duration depending on the admixture. This exposure time must be long enough. On the other hand, it must not exceed a certain period of time, because otherwise the tendency to form blockers increases disproportionately quickly. Therefore, the embodiment of the method according to the invention is expedient, because according to this embodiment the exposure time can be practically predetermined.

To carry out the method, claim 5 proposes a device in which the building material and the compressed air / excitation flow are introduced into the mouthpiece in a spatially separated manner. The space between the dense current surface and the compressed air or excitation junction is used as a swirl path for the compressed air or the exciter. Another advantage of this type is that the supply openings for the compressed air or the exciter do not match the

Building material can come into contact and clogging is practically impossible.

• Fig. 1 in abgebrochener Darstellung und schematisch den Aufbau eines Mundstücks gemäß der Erfindung,
• Fig. 2 in der Fig. 1 entsprechender Darstellung eine abgeänderte Ausführungsform der Erfindung,
• Fig. 3 in den Fig. 1 und 2 entsprechender Darstellung eine weiter abgeänderte Ausführungsform der Erfindung,
• Fig. 4 eine Variante der Ausführungsform nach Fig. 3,
• Fig. 5 eine weitere Variante der Ausführungsform nach den Fig. 3 und 4,
• Fig. 6 in Seitenansicht und schematisch die Druckluftzuführung in einem Mundstück gemäß der Erfindung,
• Fig. 7 in der Fig. 1 entsprechender Darstellung eine abgeänderte Ausführungsform der Erfindung,
• Fig. 8 eine gegenüber der Darstellung der Fig. 7 weiter abgeänderte Ausführungsform,
• Fig. 9 eine weitere Ausführungsform der Drucklufteinführung in der Fig. 6 entsprechender Darstellung,
• Fig. 10 in den Fig. 6 und 9 entsprechender Darstellung eine abgeänderte Ausführungsform der Drucklufteinführung und
• Fig. 11 in den Fig. 6, 9 und 10 entsprechender Darstellung eine weiter abgeänderte Ausführungsform.

The details, further features and other advantages of the invention result from the following description of embodiments of a device suitable for carrying out the above method with reference to the figures in the drawing; show it

• 1 in broken representation and schematically the structure of a mouthpiece according to the invention,
• 2 corresponding representation of a modified embodiment of the invention,
• 3 in FIGS. 1 and 2 corresponding representation a further modified embodiment of the invention,
• 4 shows a variant of the embodiment according to FIG. 3,
• 5 shows a further variant of the embodiment according to FIGS. 3 and 4,
• 6 in side view and schematically the compressed air supply in a mouthpiece according to the invention,
• 7 corresponding representation of a modified embodiment of the invention,
• 8 shows an embodiment which has been modified further from the representation in FIG. 7,
• 9 shows a further embodiment of the compressed air introduction in the representation corresponding to FIG. 6,
• Fig. 10 in Figs. 6 and 9 corresponding representation of a modified embodiment of the compressed air inlet and
• Fig. 11 in Figs. 6, 9 and 10 corresponding representation a further modified embodiment.

The mouthpiece 2 shown in FIG. 1 sits on the end of a delivery pipeline 3 of a known hydromechanical delivery system for shotcrete, not shown in its details, which is shown schematically at 4. The mouthpiece 2 is screwed with the aid of an annular flange 5 onto the matching annular flange 6 of the delivery pipe 3, a hose connection being switched on between the broken-off pipe 3 and a stationary delivery pipe.

The mouthpiece 2 consists of a T-shaped tube, the vertical part of which is formed by a pipe socket 7 which has the flange 5 and which branches at right angles from the comparatively narrower tube 8 of the mouthpiece. The tube 8 is connected with a flange 9 to a corresponding flange 10 of a nozzle 11, from which the building material emerges according to the arrows 12.

At the opposite end, a compressed air connection 15 is connected to a matching flange 15 'of the tube 8 with the aid of a flange 14. The details of the compressed air connection 15 result from the illustration in FIG. 6.

The compressed air supplied at 16 then enters a tubular chamber 17 and first passes the blades 18 of a guide apparatus 19. These generate a swirl with subsequent swirling of the air flow, which is indicated by the arrows 20 in the figures.

A further tube 21 is fixed concentrically in the tube chamber 17, the front end of which is provided with a cone closure 22 projecting above the guide device 19. The closure cone has a plurality of openings 23, 24 on its conical surface through which a preferably liquid exciter can emerge. In practice, the sealing cone is generally fitted with high-pressure atomizing nozzles for liquid exciters.

According to the illustration in FIG. 1, the compressed air is supplied via a nozzle 25 with a shut-off and control element 26 according to arrow 27. The exciter is also added to the pipe 21 via a pipe socket 28, a shut-off and regulating member 29 according to the arrow 30.

In operation, a piston pump continuously conveys the building material 4, consisting of a hydraulic granular to powdery substance, water, sand 31 and aggregates 32, through the nozzle 7 into the pipe 8. The strongly swirled compressed air stream behind the guide device 19 tears it out of the openings 23, 24 emerging exciter and distributes it in a mist to drop shape over the entire clear cross-section of the tube 8. In this swirled compressed air stream, the building material 4 is added at the mouth of the nozzle 7 in accordance with the hydromechanical conveying. The closed stream is broken up and broken down into particles, which are kept suspended in the compressed air stream. The building material particles carried with the stream reach the nozzle 11 and are discharged from it according to the arrows 12. In free flight they cross the distance to a surface or a mountain surface on which they accumulate in the form of a continuous layer.

According to the embodiment according to FIG. 2, the pipe socket 7, like the flanged pipe 3, is not arranged at right angles, but at an acute angle to the pipe. This favors hydromechanical conveyance by reducing the conveying resistance and can therefore have a favorable effect under certain conditions.

3, the cross section of the mouthpiece tube 8 behind the mouth of the pipe socket 7 is narrowed with a fixed diaphragm, the baffle of which is shown at 38. This chicane consists of a weir delimited by the circular tube wall, the edge of which has a rounded inner surface 39. The baffle 38 leads to a reduction in cross-section constricting the compressed air flow 40, with vortices additionally forming on the surface 39, which promote the breakup of the dense flow 41 through the pipes 3 and 7. Some of these are vertebrae shown schematically at 42.

The embodiment according to FIG. 4 uses a diaphragm 43 with a trapezoidal cross-section instead of the disk shape of the baffle 38 in order to counteract sedimentation in its flow shadow. This tendency is counteracted even more with the embodiment according to FIG. 5, because here the cross section of the diaphragm 44 in the nozzle tube 8 has a curvature 45 on which the conveying air flow 46, which forms behind the mouth of the tube 7, is accelerated.

In the embodiment according to FIG. 7, a baffle 38 is displaceable in the cross section of the nozzle tube 8 in the direction of the double arrow 36 with the aid of an adjusting device 47 in the direction of the pipe socket 7. This results in the possibility of adjustably setting an aperture 489 through which the conveying air flow has to pass immediately behind the mouth of the tube 7. With such an adjustable diaphragm, the mouthpiece 2 can also be set to different building material compositions or different water-solid matter actuators.

In the embodiment according to FIG. 8, instead of an adjustable diaphragm 38, a telescopic tube 49 which is displaceable in the tube 7 is used to adjust the diaphragm cross section 48 in the nozzle tube 8. The telescopic tube forms the extension of the pipeline 3, which can be moved and adjusted axially in the tube 7 with the aid of an annular adjusting device 50. A seal 51 seals on the jacket of the tube 49 and prevents the escape of compressed air from the compressed air stream 40 or the conveying air stream 46 in the nozzle tube 8 from the nozzle. The axial adjustability of the telescopic tube 49 enables the cross section 48 to be changed in a particularly simple manner. In addition, in the representation of FIG. 8, the tube 8 is of multiple parts, namely composed of the tube sections 52, 53 and the nozzle 54. As a result, not only can the flanged nozzle 54 be removed, but also the subsequent pipe 53, which considerably simplifies the removal of blockages and maintenance work on the mouthpiece 2.

In operation, both the excitation quantity with the shut-off and control element 29 and the compressed air quantity with the shut-off and control element 26 can be controlled. The control of the compressed air supply via the control element 26 can be carried out in such a way that the exit speed of the conveying air flow at 12 is slowed down in accordance with the structure of the layer.

The additives added to the conveyed hydraulic building material, in particular thus the exciter, are often contaminated. In many cases it is also an inhomogeneous additive. When larger amounts of such additives have to be enforced, constipation often occurs. 9, the compressed air connection 15 is provided for these conditions and has a fixed piston 56. The piston 56 has a reduced part 59, which has a connection 60 on the outside for the supply of the additive. The reduced part is hollow, the cavity continuing into the piston 56, as shown at 63. Radially oriented transverse bores 61, 62 open into parallel air channels 57, 58, which are supplied with the compressed air supplied at 16, the flow of which is thereby broken down into a plurality of partial flows. In this way, relatively wide flow channels for the additive can be realized without there being insufficient mixing of the additive and the air flow. This is because the additive is introduced into the turbulent air flow via the radial transverse bores 61, 62.

In many cases it is also necessary to introduce more than one additive, the additives only being brought together in the air flow. Embodiments for such a compressed air connection 15 are shown in FIGS. 10 and 11.

10, the piston 56 is cylindrical. It closes a chamber 70 of the tube 71, which forms the compressed air connection. However, there are a plurality of axial channels 57, 58 in the piston 56, which correspond to the design in the exemplary embodiment according to FIG. 9. In the embodiment according to FIG. 10, however, the additive is supplied at two points, namely via connections 64, 65 and the transverse bores 66, 67 to the air flow of the axial channels 57, 58, which is divided into partial flows.

A modified embodiment, which is shown in Fig. 11, also has two connections for additives, which are shown at 68 and 76. The connection 76 acts on an axial channel, which ends blindly at the above-described cone closure 22 with the openings 23 and 24. The further connection 68 supplies parallel channels 72, 73. These act on the transverse bores 74, 75 in the piston 56 and thereby feed the respective additive to the air channels 70, 71, over which the main air flow introduced at 16 is divided.

The effectiveness of one or more admixtures in the conveyed material made of concrete requires an exposure time depending on the circumstances of the individual case. This results in the longest possible, but not too long, dwell time of the concrete, which has already been mixed with the additives, in the overall device. Under these circumstances, a mouthpiece attached to a hose has the advantage that it allows the action time to be determined via the hose length and the speed of passage. A hose also has the advantage that the actual sprayer does not need to be carried or handled, but only the much lighter replacement hose in which the concrete is conveyed to the mouthpiece in the tunnel flow.

The speed of the concrete in front of the mouthpiece can be increased in order to be able to achieve the required hose length and not to extend the residence time unduly. This is expediently done by means of a discharge pipe or a discharge hose which has a smaller cross section than the concrete inlet. Such a training also has the advantage that the smallest amounts of concrete can be processed because the discharge hose has a relatively small cross-section.

As far as the mouthpiece is provided with a nozzle, the usual pressure conversion into speed results in the nozzle. If such an increase in speed is not required on the discharge, the nozzle can also be dispensed with.

Claims (15)

1. A process for the pneumatic output of hydromechanically transported hydraulic building material in underground mining, wherein compressed air (40) is added to the wet, pumped building material (4) in the intense stream (41) in front of a mouthpiece (11) serving as the output, being in particular nozzle-shaped, and is ejected with the building material, wherein an agitator is added to the compressed air (40) prior to addition to the intense stream (41), characterised in that, the flow of compressed air (40) is swirled before striking the intense stream (41), the agitator is dispersed in the swirled flow of compressed air (40) and the flow of compressed air (40) is added to the intense stream (41) of pumped building material (4) in the direction of delivery after the swirling stretch of the compressed air flow (40) which is sealed against outside air by the wet building material (4) and is thereby dispersed in the building material (4), as well as being fed to, and outputted from the mouthpiece (11).

2. A process according to Claim 1, characterised in that the stream of compressed air (40) and thus the output speed of the flow of the supply air (46) is controlled by compressed air addition via a locking and regulating member (26).

3. A process according to Claim 1 or 2, characterised in that, after the bringing together of the flow of compressed air (40) and the intense stream (41) the flow of supply air is constricted and then widened before it is outputted.

4. A process according to any of Claims 1 to 3, characterised in that the supply flow is conducted through a delivery pipe or a delivery hose, through the length and reduced cross-section of which the operational time of one or several additive agents is determined reative to the delivery speed of the fluid current.

5. Apparatus for the carrying out of the process in a mouthpiece (2), preferably provided with a nozzle (11), of a supply pipe or hose connection (3) of a hydromechanical conveyer system, in particular for the output of shotcrete or mortar on the rock casing of underground excavations, wherein the mouthpiece (2) forms the end of a pneumatic supply pipe (3) into which a feed pipe (25) for compressed air and an agitator mixed with this opens, characterised in that the mouthpiece (2) has a pipe support (7) on its side into which the supply pipe or hose connection (3) opens, and that the mouthpiece (11) has a pipe- shaped extension beyond the pipe support (7) whose end opposite the outlet (12) of the mouthpiece is closed and is provided with a compressed air lead-in (25) to which a swirling mechanism (19) is added.

6. Apparatus according to Claim 5, characterised in that the compressed air lead-in (25) has a pipe chamber (15) with a control device (19) having blades (18) for producing swirls (20) in the compressed air flow.

7. Apparatus according to Claim 5 or 6, characterised in that a pipe (21) is arranged concentrically in the pipe chamber (15) for the supply of agitators, the inside end of which is provided with a closure (22) which has apertures (23, 24) for the introduction of the agitators into the compressed air flow (40).

8. Apparatus according to any of Claims 6 and 7, characterised by a screen behind the junction of the pipe support (7) in the mouthpiece (2) for the fixed or adjustable constriction of the supply air flow (46) in a part cross section (48) of the mouthpiece pipe (8).

9. Apparatus according to any of Claims 5 to 8, characterised in that a baffle (38,43,44) serves as the screen.

10. Apparatus according to any of Claims 5 to 9, characterised in that a telescopic tube (49) serves as the screen and is movably arranged and sealed in the pipe support (7) of the mouthpiece pipe (8).

11. Apparatus according to any of Claims 5 to 9, characterised in that the air flow is dispersed in the pipe chamber (15) into a number of axial channels (57, 58) which have radial apertures (61, 62) through which the agitator is introduced into the air flow.

12. Apparatus according to any of Claims 5 to 11, characterised in that the axial channels (57, 58) and the radial apertures (61, 62) are formed in a piston (56) which closes the pipe chamber (70).

13. Apparatus according to any of Claims 5 to 12, characterised in that the piston (56) forms a constructional unit with a pipe piston (59) of reduced cross-section in which an axial aperture (63) is formed for the central supply of agitators to the radial apertures (61, 62).

14. Apparatus according to any of Claims 5 to 13, characterised in that the pipe piston has a concentric inner blind bore which is closed by a conical closure (22) which has drilled holes (23, 24), and that one or more concentric outer axial channels (72, 73) serve for the delivery of one or more additive agents to radial apertures (74, 75).

15. Apparatus according to any of Claims 5 to 14, characterised in that the radial apertures (66, 67) in the piston (56) terminate at outwardly disposed connections (64, 65) for one or more agitators.

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