Present invention relates to mining industry. Particularly, the invention relates to an arrangement and a method at rock reinforcement, for example in conjunction with tunnelling.

BACKGROUND

In conjunction with tunnelling or in a mine, cracks in the rock layers often arise around a cavity in a mountain through which for example a future tunnel will run. The cracks weaken the mountain, which may result in that parts of the mountain may collapse. Therefore actions are needed that reduce the risk for collapse. The actions are usually called rock reinforcement. A common method for rock reinforcement is rock bolting. Rock bolting means that a bolt adapted for rock bolting is fastened in a drilled hole by a molding agent that is injected into the hole be using a system adapted for use at rock reinforcement. In this way binds and keeps the layers together and thus reduces the risk of race. After injection of the molding agent into the hole, some parts of the system may need to be flushed clean to be used in another hole to be filled with the molding agent. JP19850274361 describes a system for injection of a thermosetting plastic that is injected into a form for manufacturing of products.

SUMMARY

An object of the present invention is making a process of anchoring a bolt in a rock hole at rock reinforcement more efficient.

According to one aspect of the invention, the object is achieved by an arrangement for use at rock reinforcement, comprising a pump connected to a mixer through a first line, wherein the mixer is adapted to create a mixture comprising at least two components intended to be injected into a rock hole to achieve said rock reinforcement. The mixer may also be called a blender is therein adapted for use at rock reinforcement by the construction and the size and by the material the mixer is made of to create said mixture in an efficient way. The pump is connected to a source for a flushing fluid, and is arranged to create a stream of the flushing fluid through the first line to the mixer for flushing of the mixer. The flushing fluid, as flushing liquid may thereby be pumped, using the pump, from the source to the mixer through the first line for flushing the mixer, i.e. for cleaning of the mixer from at least the mixture of the at least two components that may be caught on the inside of the mixer.

The arrangement comprises also an adapter arranged downstream of said mixer. The adapter is thereby arranged after the mixer in relation to the flow of the flushing liquid. With other words the flushing liquid passes the mixer before it reaches the adapter when the flushing fluid is pumped from said source

The adapter is arranged to be set in a component injection mode where the mixture is injected into the rock hole and a flushing mode where the flushing fluid is guided from the mixer and out from the adapter during flushing of the mixer. In this way the adapter may be switched between the component injection mode and the flushing mode. The adapter may also be called flow director and it has the task to control and to guide different flows through the adapter and for example through different channels in the adapter in different phases during a rock reinforcement process. The adapter may thereby be switched from the component injection mode to the flushing mode, after for example a finished injection of the mixture into the rock hole. Furthermore, the adapter can be changed immediately after a finished injection of said mixture.

Since the adapter can be switched from component injection mode to the flushing mode, the mixer can be flushed immediately after injection of the mixture into the rock hole has been completed. Thereby an arrangement is achieved which allows flushing of the mixer immediately after a finished injection of the component mixture into the rock hole. Thus, it is not necessary to wait for the component mixture to solidify in the rock hole and around a rock bolt placed in the hole to flush the mixer. In this way, the process of anchoring the bolt in the rock hole at rock reinforcement may be more efficient.

Since the flushing fluid is directed from the mixer and out of the adapter during flushing of the mixer in said flushing mode, the flushing fluid may be guided so that it flows through the mixer, into the adapter and further out from the adapter. Thus, the flow of the flushing fluid may be controlled to flow out of the adapter. Further, the adapter is arranged to abut the bolt placed in the rock hole during the flushing of the mixer. Thus, the adapter is arranged to have contact with the bolt and to hold the bolt during the flushing of the mixer so that the bolt substantially maintains its mode in the rock hole after the mixture has been injected.

Injecting of the mixture into the hole can cause forces acting on the bolt and which can push the bolt out of the rock hole even after the mixture has been injected. The bolt can also be influenced by gravity forces, i.e. gravidity that in case of holes drilled

substantially upwards my cause the bolt to slide out from the hole. However, these forces are efficiently counteracted by means of said adapter which is arranged to abut the bolt and hold the bolt during flushing of the mixer.

Thus, the mixer may be flushed clean directly after a finished injection of the mixture into the rock hole while the bolt is held in place in the rock hole using the adapter. Thereby, an arrangement for use in rock reinforcement is provided by means of which anchoring of a bolt in a rock hole at rock reinforcement can be made more efficient, i.e. the time required for anchoring a bolt in a rock hole can be shortened.

Thus, an arrangement for use at rock reinforcement is provided which can achieve the object mentioned above.

According to some embodiments the arrangement comprises a second line connected to the adapter so that during flushing of the mixer the flushing fluid is guided into the second line. As described above, the adapter is arranged such that in the flushing mode the flushing fluid is conveyed from the mixer and out from the adapter. Further, since the arrangement comprises the second line connected to the adapter so that during flushing of the mixer, the flushing medium is guided into the second line, the flushing medium can be guided away from the adapter under controlled forms through the second line. The second line that is connected to the adapter also creates the opportunities to guide the flushing fluid a longer distance from the adapter after the flushing fluid has passed the mixer during flushing of the mixer, this compared with an arrangement without the second line. The second line may be connected to a first tank. Thus, the flushing liquid can be guided from the adapter to the first tank when flushing the mixer. Thus, the flushing fluid may be collected in the first tank after the flushing fluid has passed the mixer during flushing of the mixer.

According to some embodiments the source may comprise a second tank containing the flushing fluid. By this, the flushing liquid can be easily stored in the second tank and moved when needed by moving of the second tank. Thus a mobile source for flushing fluid is provided.

According to some embodiments, the second line is connected to the second tank. Thereby, the flushing liquid can be guided back the second tank during flushing the mixer. Since the flushing liquid can be returned to the second tank, it can be recycled and reused during flushing of the mixer. Thus, a smaller amount of flushing liquid is needed for flushing the mixer as compared to whether the flushing liquid would not be recirculated. Thereby an arrangement is provided that can make the use of flushing liquid more efficient during flushing of the mixer.

The arrangement may comprise a filter arranged filtering the flushing fluid from the mixture that follows with the flushing fluid during flushing of the mixer. Thus, the flushing medium may be purified from the mixture after the flushing medium has passed the mixer during flushing of the mixer. The mixture is caught in the filter instead of continuing flowing with the flushing medium. Thereby, an improved arrangement for use at rock reinforcement is provided considering for instance environmental aspects. Furthermore, the filtered flushing fluid can be reused and recirculated in a closed system for flushing fluid.

According to some embodiments the filter may be arranged at the second tank. Thus, the filter may be arranged in the close to the second tank or in connection with the second tank. As an alternative, the filter may be arranged in the second tank, i.e. may be integrated with the second tank. In this way, the flushing fluid can be filtered before the flushing fluid flows into the second tank. Thus, the second tank is protected from the mixture that flows with the flushing fluid during flushing of the mixer, which mixture may adhere to the inner walls of the second tank. Furthermore, a compact arrangement for use at rock reinforcement can be provided as the filter can be integrated in the second tank.

The arrangement may comprise a pressure device arranged applying a pressure force towards the adapter so that the adapter abuts the bolt during flushing of the mixer. Thus, the pressure device may act on the adapter and push the adapter towards the bolt so that the bolt is held in the rock hole in substantially the same mode after injection of the mixture. Furthermore, thanks to the pressure device, the pressure force applied to the adapter can be controlled and adapted to different operating conditions during rock reinforcement. Thus, forces that act on a bolt and which can cause the bolt to be moved from the rock hole are counteracted in an efficient and controlled manner. By this, the risk that the bolt may be pressed out or slide out from the rock hole during flushing of the mixer may be reduced. Thus, an arrangement is provided that may facilitate and improve that a bolt being placed in a rock hole to provide efficient rock reinforcement.

According to some embodiments the adapter may comprise a connection portion adapted for connection to the bolt. Thus, the adapter may abut the bolt and contact the bolt through the connecting part. The connecting part is adapted for connection to the bolt through, for example, shape and material, and by this it can be adapted to the bolt when contacting the bolt. In this manner, an improved connection between the adapter and the bolt is provided as the adapter tightly abuts the bolt through the connection portion.

The arrangement may be adapted to be mounted at a vehicle. Thereby, the arrangement may be fixed to a vehicle and by this to provide a mobile arrangement that can change the position of the arrangement using the vehicle when the arrangement has been mounted on the vehicle.

The object mentioned above is achieved according to a second aspect of the present invention by a method at rock reinforcement that is performed using an arrangement comprising: a pump connected to a mixer through a first line, wherein the mixer is adapted to create a mixture comprising at least two components intended to be injected into a rock hole to achieve the rock reinforcement, wherein the pump is connected to a source for a flushing fluid, and is arranged to create a stream of the flushing fluid through the first line to the mixer for flushing of the mixer and an adapter arranged downstream of the mixer, wherein the adapter is arranged to be set in a component injection mode where the mixture is injected into the rock hole and a flushing mode where the flushing fluid is guided from the mixer and out from the adapter during flushing of the mixer, wherein the adapter is arranged to abut the bolt placed in the rock hole during flushing of the mixer. The method comprises switching the adapter from the component injection mode to the flushing mode after the mixture has been injected into the rock hole. Thus, the mixer may be flushed clean directly after a finished injection of the mixture into the rock hole.

Further, the method comprises starting the pump to create a flow of the flushing fluid through the first line to the mixer to flush the mixer. Thereby, the flushing medium such as flushing liquid can be pumped using the pump from the source to the flushing mixer through the first line i.e. for cleaning the mixer.

The method comprises also applying a pressure force towards the adapter so that the adapter abuts the bolt during flushing of the mixture. Thus, the pressure device may act on the adapter and push the adapter towards the bolt so that the bolt is held in the rock hole in substantially the same mode after injection of the mixture. Further the pressure force applied to the adapter can be controlled and adapted to different operating conditions during rock reinforcement. Thus, forces that act on a bolt and which can cause the bolt to be moved from the rock hole are counteracted in an efficient and controlled manner. By this, the risk that the bolt may be pressed out or slide out from the rock hole during flushing of the mixer may be reduced.

Accordingly, a method at rock reinforcement is provided by which anchoring of a bolt in a rock hole at rock reinforcement can be done more efficiently i.e. the time required for anchoring a bolt in a rock hole can be shortened.

Thus, a method at rock reinforcement is provided that can achieve the object mentioned above.

The method may comprise activating a pressure device to create said pressure force. Thereby, the pressure force applied to the adapter can be controlled and adapted to different operating conditions during rock reinforcement in a simple manner by activating the pressure device. According to some embodiments the method may comprise filtering the flushing fluid using a filter from said mixture that follows with the flushing fluid during flushing of the mixer. Thereby, the flushing medium may be purified from the mixture after the flushing medium has passed the mixer during flushing of the mixer. The mixture is caught in the filter instead of continuing flowing with the flushing medium. Thereby, an improved arrangement for use at rock reinforcement is provided considering for instance environmental aspects. Furthermore, the filtered flushing fluid can be reused and recirculated in a closed system for flushing fluid.

BRIEF DESCRIPTION OF THE DRAWINGS

The further aspects of the subject matter, including their particular features and advantages, will be readily understood from the following detailed description of one or several embodiments provided with reference to the accompanying drawings, where:

Fig. 1 is a schematic illustration of an arrangement according to one embodiment, Fig. 2 is a schematic illustration of an arrangement according other embodiments, Fig. 3 is a perspective view of an adapter comprised in the arrangement according to Fig. 1 or 2 and

Fig. 4 is a flowchart showing a method at rock reinforcement. DETAILED DESCRIPTION

The embodiments herein will now be described in more detail with reference to the accompanying drawings, in which example embodiments are shown. Disclosed features of example embodiments may be combined. Like numbers refer to like elements throughout.

Fig. 1 illustrates an exemplary embodiment of an arrangement 1 for use at rock reinforcement, or sometimes called rock bolting. Figure 1 also illustrates also a cross section through a rock hole 2 in a mountain where a rock bolt 13 has been placed.

In general, when a mountain needs to be reinforced, a rock hole is drilled in the mountain. This can be done using a drill or by means of a self-drilling rock bolt. A self- drilling bolt comprises a drill bit illustrated in Fig. 1 with reference 4. Thus, the rock bolt 13 in Fig. 1 illustrates a self-drilling bolt. A self-drilling rock bolt is placed in a rock hole while the rock hole is being created, i.e. is drilled be using the self-drilling bolt. Self- drilling rock bolts are known in the art and are therefore not described more in detail herein.

After a bolt adapted for rocks has been placed in a rock hole, it is anchored in the rock hole by using a molding agent injected into the rock hole. The molding agent solidifies, or is hardened inside the rock hole and around the rock hole, and by this the bolt adapted for rocks is anchored inside the rock hole. With other words the bolt adapted for rocks is fastened in the rock hole by using the molding agent.

A bolt adapted for rocks that has been anchored in a rock hole reinforces the mountain at and around the rock hole.

A self-drilling bolt usually comprises a channel within the bolt through which said molding agent can be injected into the rock hole. Thus, a self-drilling rock bolt can be hollow so that the component mixture can be injected through the rock bolt and out through a drill bit placed outermost on the bolt.

The molding agent may be a component mixture which may comprise two components. According to embodiments shown in Fig. 1 , components A and B can be injected into the rock hole 2. The components A and B can be injected by means of a component device 6 comprising channels (not shown) for guiding of components A, B into a mixer 7 where the components are mixed together. The component device 6 may also comprise a channel (not shown) for conveying the flushing fluid to the mixer 7. The flushing fluid 7 may be guided at least partially through the channel for the component A.

The components A and B are intended for use at rock reinforcement, i.e. the components are produced for this purpose. The first component may contain a hardener such as sodium silicate, an alcohol, a polyol or the like or a combination thereof. The second component may contain a resin such as diphenylmethane diisocyanate (MDI) or the like.

The first component and the second component are intended to be mixed with each other when injected into the rock hole when a mixture is created. Once the components have been mixed together, a reaction of the resin is triggered by the hardener which causes the resin to form crosslinking which causes the mixture to harden. The arrangement 1 comprises a pump 3, such as for example a radial pump. The pump 3 is connected to the mixer 7 via a first line 5. The first line 5 may comprise a hose or a tube. The mixer 7 is arranged to create the mixture, as described above, comprising at least the two components A, B. Thus, the mixer 7 is adapted for use at rock reinforcement by its construction and size as well as by material of which it is made. The mixer 7 may comprise a mesh-like inner part by means of which components A and B can be mixed within the mixer 7 when they pass through the mixer 7. The mixer 7 may be made of metal or a plastic material adapted for use in contact with various components intended for use at rock reinforcement.

As it is shown in Fig. 1 , the pump 3 is connected to a source 9 for a flushing fluid. The flushing fluid may comprise water or oil or the like. In case of water being used as a flushing fluid, the source 9 of the flushing fluid may be a water network, for example a drinking water network. In other words, the pump 3 can be connected to a water pipe (not shown) for a municipal or local water supply system. The source 9 may also comprise a second tank 19 containing the flushing fluid. The second tank is described in detail in conjunction with Fig. 2.

The pump is and is adapted to create a flow of the flushing fluid through the first line 5 to the mixer 7 for flushing the mixer 7.

During the process when the above-described components A and B are injected into the rock hole through the mixer 7, the components A and B or the mixture of components A and B can get caught on the inside of the mixer 7 which may cause the mixer to clog and to be blocked. In order to avoid the mixer 7 to clog and being blocked and for reusing the mixer 7, the mixer 7 needs to be flushed after a completed injection of components A and B.

Since the pump 3 is arranged to create a flow of the flushing fluid through the first line 5 to the mixer 7 for flushing the mixer 7, the mixer 7 can be flushed clean, i.e.

cleaned after a final injection of components A, B.

The flow of the flushing fluid draws any residues of the mixture or at least one of the components A and B which has been stuck on the inside of the mixer 7 during the flushing of the mixer 7. Thus, the mixer 7 is cleaned and prepared for reuse. Further, the arrangement 1 comprises an adapter 1 1 arranged downstream of the mixer 7. The adapter is thus arranged after the mixer 7 in relation to the flow of flushing fluid from the source 9. In other words, the flushing fluid passes the mixer 7 before it reaches the adapter 1 1 when the flushing fluid is pumped from said source 9 using the pump 3. The mixer 7 is arranged between the component device 6 and the adapter 1 1 so that the flushing fluid can be guided through the component device 6, through the mixer 7 and into the adapter 11 in the flow direction created by the pump 3. The adapter 1 1 may have direct contact with the mixer 7. Alternatively, a contact element (not shown) between the mixer 7 and the adapter 1 1 may be used. The contact element may be a seal adapted for use between the mixer 7 and the adapter 1 1. The mixer 7 may be mounted to the adapter 1 1 by, for example, a threaded connection between the mixer 7 and the adapter 1 1. In other words, the mixer 7 can be screwed to the adapter 1 1. In this manner the adapter 11 and the mixer 7 can be moved together towards and from the bolt 13. As illustrated in Fig. 1 , the adapter 1 1 is arranged to be set a first mode where the above-described mixture can pass the adapter 1 1 and continue into the rock hole 2. The first mode is called a component injection mode in which mixture is injected into the rock hole 2. The component injection mode of the adapter 1 1 is symbolized but the arrow 8 in Fig. 1. The arrow 8 symbolizes a first channel of the adapter 1 1 which connects an outlet 12 of the mixer 7 with an inlet 14 of the rock bolt 13. Thus the adapter 1 1 comprises a first channel which can connect the outlet 12 with the inlet 14 when the adapter 1 1 has been mounted between the mixer 7 and the bolt 13.

Furthermore, the adapter 1 1 is adapted to be set in a second mode where the flushing medium can be passed from the mixer 7 and out of the adapter 1 1 through a first adapter outlet 16 of the adapter 11. The second mode is called a flushing mode where the flushing medium is guided from the mixer 7 and out from the adapter 1 1 during flushing of the mixer 7. The flushing mode of the adapter 11 is symbolized by the arrow 10. The arrow 10 symbolizes a second channel connecting an outlet 12 of the mixer 7 with the first adapter output 16 of the adapter 1 1. The first channel and the second channel may have a common sub channel. In the flushing mode of the adapter 1 1 at least a portion of the first duct can be closed so that the inlet 14 of the bolt 13 is blocked and by this flushing liquid is prevented from coming in contact with the mixture injected into the rock hole 2. The adapter 11 may comprise a control element (not shown) arranged to enable change, i.e. switch between component injection mode and flush mode. In other words, the adapter 1 1 can be switched between the component injection mode and the flushing mode using the control element. The control element may be operated manually by an operator or, for example, electrically or hydraulically. An example of an adapter 11 is illustrated in Figure 3 and described in detail in conjunction with Fig. 3. According to some embodiments, the first adapter outlet 16 may be connected with a second line 15. The second line 15 may be a hose or tube connected to the adapter 11 for guiding of the flushing fluid out from the adapter 1 1 during flushing of the mixer 7. The adapter 1 1 is arranged to abut the bolt 13 placed in the rock hole 2 during flushing of the mixer 7. Thus, the adapter 11 is arranged to have contact with the bolt 13 and to hold the bolt 13 during the flushing of the mixer 7 so that the bolt 13 substantially retains its position in the rock hole 2 after the mixture has been injected into the rock hole 2. The adapter 1 1 may comprise a connecting portion 23 adapted for connection to the bolt 13. The connecting portion 23 may, for example, be made of rubber material.

According to some embodiments shown in Fig. 1 , the arrangement 1 may comprise a pressure device 22 adapted applying a pressure force F towards the adapter 11 so that the adapter 1 1 may abut the bolt 13 during flushing the mixer 7. In Fig. 1 only a part of the pressure device 22 is shown, namely the part of the pressure device 22 acting on the adapter 11. The pressure device 22 is arranged to press the adapter 1 1 and push the adapter 11 towards the bolt 13 with the pressure force F such that the bolt 13 is held in the rock hole 2 in substantially the same position after injection of the mixture. Thus, a force T acting on the bolt 13 in a substantially opposite direction to the direction of the pressure force F acts on the adapter 1 1 , can be counteracted by the pressure device 22. The force T may occur while the mixture is injected into the hole 2 and even after the mixture has been injected. This, due to residual compressive force from the injection that may act on the bolt. The force T may comprise gravity forces acting on the bolt 13. This at the hole drilled substantially upward as gravity forces may cause the bolt 13 to slide out from the rock hole 2.

The pressure device 22 may be controlled, for example, hydraulically or electrically for the purpose of creating said compressive force F acting on the adapter 1 1. The pressure force F may be equal to or greater than the force T, wherein the pressure force may be controlled depending on the magnitude of the force T. The pressure device 22 may comprise a connection means 18 for connection to the adapter and for transferring of the compressive force F to the adapter 1 1. Connection means 18 may comprise rubber, metal or other suitable material. The arrangement 1 may comprise a filter 21 arranged filtering the flushing fluid from the mixture follows the flushing fluid during flushing of the mixer 7. As illustrated in Fig. 1 , the filter 21 can be placed along the second line 15. Thus, the flushing fluid can be purified from at least the mixture after the flushing fluid has been passed the mixer during flushing of the mixer. The mixture gets caught in the filter instead of continuing with the flushing fluid.

The filter 21 is adapted for use at rock reinforcement and for filtering the flushing liquid. For example, the filter 21 may be a membrane filter. Fig. 2 illustrates an arrangement 1 for use at rock reinforcement, the arrangement 1 is shown according to other embodiments compared to Fig. 1.

According to some embodiments, the second line 15 may be connected to a first tank 17 or to a second tank 19. Thus, the arrangement 1 may comprise a source for the flushing liquid as described in Fig. 1 and the first tank 17. Alternatively, the source may comprise or consist of the second tank 19 containing the flushing liquid and the arrangement 1 may then comprise the first tank 17.

Thus, the pump 3 may be connected to, for example, a water pipe connected to a water network, whereby water can be pumped by means of the pump 3 for flushing the mixer 7 and may be collected in the first tank 17 connected to the second line 15 after water has passed the mixer 7.

Alternatively, the pump 3 may be connected to the second tank 19 containing a flushing fluid whereby the flushing fluid may be guided via the second line 15 to the first tank 17 or back to the second tank 19. Thus, the flushing liquid may be recycled and reused during flushing of the mixer 7 if the flushing fluid is led back to the second tank 19. Thus, a smaller amount of flushing liquid is required for flushing the mixer as compared to whether the flushing liquid would not be recirculated. The arrangement may comprise an additional filter 25 which may be positioned upstream of the pump 3. Thus, the flushing fluid may be filtered before it reaches the pump 3. By this the pump is protected from, inter alia, residues of the mixture which can follow the flushing liquid during flushing of the mixer 7. The filter 21 may be a coarse filter, i.e. may be adapted to capture larger pieces of the mixture from the mixer 7, while the additional filter 25 may be a fine filter adapted to capture smaller pieces of, for example, the mixture.

The filter 21 can be placed along with the second line 15 or the filter 21 may be integrated into the first tank 17 or in the second tank 19. In other words, the filter 21 may be built into the first tank 17 or in the second tank 19.

Thanks to the filter 21 , the first tank 17 or the second tank 19 is protected from residues of the mixture which may follow the flushing medium during flushing of the mixer 7. Thus, the risk of the first tank 17 or the second tank 19 is filled with residues of the mixture is minimized, which the residues follow with the flushing fluid and that may adhere to the inner walls of the first tank 17 or the second tank 19.

Thereby, also service of the arrangement 1 is facilitated, because the filter 21 may be replaced when necessary and after a certain period of time instead of replacing the first tank 17 or the second tank 19 which would be required in case if the residues of the mixture would end up in the first tank 17 or in the second thought 19.

Fig. 3 shows an example of an adapter 1 1 that can be mounted in an arrangement 1 according to any of the above-described embodiments.

The adapter 1 1 may comprise an adapter inlet 27, a first adapter outlet 16 and a second adapter outlet 29. The adapter inlet 27 and the second adapter outlet 29 are comprised in and form a part of a first channel 31 in the adapter 1 1. Adapter inlet 27 and the first adapter outlet 16 are comprised in and constitute a part of a second channel 33 in the adapter 1 1. As illustrated in Figure 3, the mixer 7 may be positioned at the adapter 1 1 so that the outlet 12 of the mixer 7 faces the adapter inlet 27. The adapter 1 1 may be positioned so that the bolt 13 abuts the adapter 11 and the adapter outlet 29 faces the inlet 14 of the rock bolt 13. Further, the second line 15 may be connected to the adapter 11 so that the second line 15 is connected to the first outlet 16 of the adapter 1 1.

The adapter 1 1 also comprises a control piston 20 disposed substantially axially in the adapter 11 so as to permit an axial movement of the control piston 20 along an axle A. The axial movement of the control piston 20 is controlled by a control element (not shown) which may be driven hydraulically or electrically.

The control piston 20 may be positioned in at least a first position p1 and a second position p2. In the first position p1 , a connection between the adapter inlet 27 and the adapter outlet 29 is created. In other words, in the first position p1 of the control piston, the first channel 31 is open. In the first position p1 , the mixture of previously described components A and B can be injected into the rock hole, for example through the bolt 13 and more specifically through the inlet 14 of the rock bolt 13.

In the second position p2 of the control piston 20, the inlet 14 of the rock bolt 14 is closed and at the same time the second channel 33 is opened, thereby a connection between the adapter inlet 27 and the first outlet 16 is created. In the second position p2 of the control piston 20, a passage of the flushing fluid is allowed from the mixer 7 and through the adapter 1 1 and, for example, into the second line 15. Thus, the adapter 1 1 makes it possible to flush the mixer 7 immediately after a final injection of the above-described mixture.

Arrangement 1 is primarily intended to be mounted on a vehicle, for example a drill rig, wherein at least some of the components of the arrangement 1 comprises attachment details for mounting at the vehicle.

Fig. 3 illustrates only one possible embodiment of the adapter 1 1 intended for use at rock reinforcement. The adapter 1 1 may comprise a rotary control element and may have different embodiments with respect to channels through the adapter 1 1. Fig. 4 shows an exemplary method 100 at rock reinforcement which is performed by means of arrangement 1 as above. The method 100 can be performed, for example, by a control unit (not shown). According to some embodiments, the method 100 may comprise switching 101 the adapter from the component injection mode to the flushing mode after the mixture has been injected into the rock hole, further starting 103 the pump to create a flow of the flushing fluid through the first line to the mixer to flush the mixer and applying 105 a pressure force towards the adapter so that the adapter abuts the bolt during flushing of said mixture.

Accordingly, a method at rock reinforcement is provided by which anchoring of a bolt in a rock hole at rock reinforcement can be done more efficiently i.e. the time required for anchoring a bolt in a rock hole can be shortened since the mixer can be flushed immediately after a final injection of the mixture into the rock hole while the bolt can be held in place in the rock hole and pressed towards the rock hole, i.e. while the mixer is flushed.

The method 100 may further comprise activating 107 a pressure device to provide said pressure force.

As an alternative, the method 100 may comprise filtering 109 said flushing fluid using a filter from the mixture that follows with the flushing fluid during flushing of the mixer.