AU2009290778A1

AU2009290778A1 - Method for handling drill cuttings, dust collection system for rock drilling rig, and changer unit

Info

Publication number: AU2009290778A1
Application number: AU2009290778A
Authority: AU
Inventors: Hannu Paukkunen; Ossi Tienari
Original assignee: Sandvik Mining and Construction Oy
Current assignee: Sandvik Mining and Construction Oy
Priority date: 2008-09-10
Filing date: 2009-09-09
Publication date: 2010-03-18
Also published as: CN102149897A; FI20085848L; EP2321490A1; WO2010029216A1; EP2321490A4; FI20085848A0; EP2321490B1; JP5289570B2; JP2012500348A

Description

WO 2010/029216 PCT/F12009/050721 1 METHOD FOR HANDLING DRILL CUTTINGS, DUST COLLECTION SYSTEM FOR ROCK DRILLING RIG, AND CHANGER UNIT BACKGROUND OF THE INVENTION [0001] The invention relates to a method for handling drill cuttings, in which method the drill cuttings are directed away from a drill hole by means of a dust collection system. [0002] The invention further relates to a dust collection system for a rock drilling rig, the system comprising at least a suction funnel to be placed on the mouth of the drill hole, a suction device generating suction in the system, at least one dust separator and a duct leading from the suction funnel to the dust separator. [0003] The invention relates yet to a changer unit for directing drill cuttings. [0004] When rock and soil are drilled, drilling produces large amounts of dust. When a drill hole is typically flushed, for instance, with pres surized air, liquid or a combination thereof, the dust tends to spread to the en vironment along with the substance used for flushing. It is important to prevent the dust from spreading, not only from the viewpoint of occupational health of the drilling apparatus operator but also from the viewpoint of the environment, in particular when drilling takes place in the vicinity of densely populated areas or other settled areas, or in mines, for instance. For removal of dust from rock drilling rigs there have been developed various dust collection systems where with dust is to be moved away from the drilling site and/or treated, for instance, by separating the discharge air for dusty rock material and other solids. Typi cally, the separation employs particular dust separators, for instance. [0005] When rock and soil are drilled, occasionally so-called water holes are encountered, i.e. the drill hole contains water that has leaked in ei ther from outside the hole or through the bottom or walls of the hole. This causes problems in using dust separation systems, because access of water into a dust separator jeopardizes the operation of the apparatus. Because it is generally difficult to predict the occurrence of water holes, quick intervention in the problem requires constant presence and high alertness of the operator of the apparatus. In addition, known solutions are, in practice, based on detach ing the dust removal system from the hole, which entails a problem that, for instance, aqueous drill cuttings slide back into the drill hole when drilling WO 2010/029216 PCT/F12009/050721 2 ceases, or on interrupting suction in the dust removal, which may cause a blockage of drill cuttings in a dust tube leading to the dust separator. BRIEF DESCRIPTION OF THE INVENTION [0006] The object of the present invention is to provide a novel and improved method for handling drill cuttings, a dust collection system for a rock drilling rig and a changer unit. [0007] The method of the invention is characterized by directing drill cuttings in the dust collection system with at least one changer unit having at least a first and a second operating position and by determining water content in the drill cuttings and directing the drill cuttings, according to the water con tent in the drill cuttings, in the first operating position to one or more dust sepa rators and in the second operating position away from the dust collection sys tem before the dust separator. [0008] The system of the invention is characterized by comprising at least one changer unit having at least two operating positions, in the first of which operating positions there will be provided a continuous duct from the suction funnel to the dust separator and in the second of the operating posi tions there will not be provided a continuous duct from the suction funnel to the duct collector, and consequently drill cuttings are directed away from the dust collection system before the duct separator. [0009] The changer unit of the invention is characterized by being arrangeable in at least two operating positions in the first of which operating positions there will be provided a continuous duct from an inlet duct of drill cut tings to a discharge duct of drill cuttings and in the second operating position the duct from the inlet duct to the discharge duct of drill cuttings is cut. [0010] The basic idea of the invention is that it is possible to select an operating position, in which drill cuttings are directed away from the dust collection system before the dust separator if the water content in the drill cut tings rises so high that it could damage the operation of the dust separator. This may be implemented, for instance, by arranging in the dust collection sys tem for drilling or in connection thereof a changer wherewith it is possible to prevent access of exceedingly aqueous drill cuttings into the dust separator. [0011] The invention has an advantage that when water content in the drill cuttings rises excessively high, the drill cuttings may be readily di rected such that they have no access to the dust separator to damage its op- WO 2010/029216 PCT/F12009/050721 3 eration. Further, the invention has an advantage that wet drill cuttings are pre vented from blocking a dust tube leading to the dust separator. [0012] The basic idea of an embodiment is that at least one upper limit value is set for water content in drill cuttings, and when the upper limit value is exceeded, the drill cuttings are directed away from the dust collection system before the dust separator. This embodiment has an advantage that selection of the operating position may be made more explicit and information on the limit value being exceeded may be conveyed to the operator of the drill ing apparatus. In addition, determination of a limit value is generally, in prac tice, a prerequisite for automatic control of the selection of operating position. [0013] The basic idea of an embodiment is that the operator of the drilling apparatus assesses water content in drill cuttings on the sensory basis and selects manually whether the drill cuttings are directed to the dust separa tor or away from the dust collection system before the dust separator. This embodiment has an advantage that it is simple to implement. [0014] The basic idea of an embodiment is that water content in drill cuttings is determined automatically and information on the moisture of drill cuttings is conveyed to the operator of the drilling apparatus, who selects manually, whether the drill cuttings are directed to the dust separator or away from the dust collection system before the dust separator. This embodiment has an advantage that observation of changes in water content becomes eas ier and there will be less chances of human error. [0015] The basic idea of an embodiment is that water content in drill cuttings is determined automatically and the information is conveyed to a con trol unit which selects an operating position on the basis of the water content in drill cuttings, whereby the drill cuttings are directed either to the dust separator or, when the water content is excessively high, away from the dust collection system before the dust separator. This embodiment has an advantage that it further reduces the chance of human errors and facilitates the work of the op erator of drilling apparatus, because in conventional solutions the monitoring of the rise of the water content in the drill cuttings typically requires constant presence and high alertness of the operator of the drilling apparatus during drilling. [0016] The basic idea of an embodiment is that automatic determi nation of water content employs at least one moisture detector. This embodi- WO 2010/029216 PCT/F12009/050721 4 ment has an advantage that in water content detection it is possible to use a commercially available sensor. [0017] The basic idea of an embodiment is that excessively aque ous drill cuttings removed from the dust collection system before the dust separator are directed at a distance from the drill hole. This embodiment has an advantage that the excessively aqueous drill cuttings are not allowed to slide back into the drill hole after the drilling ceases, and thus make the edges or walls of the drill hole collapse. [0018] The basic idea of an embodiment is that the dust collection system or the changer unit comprises a control unit that is arranged to select and change the operating position of the changer unit in accordance with the water content in the drill cuttings. This embodiment has an advantage that it enables automatic control of the operating position without the operator of the drilling apparatus having to participate therein. [0019] The basic idea of an embodiment is that a changer unit com prises a control part, which is arranged, in the second operating position of the changer unit, in which the drill cuttings are directed away from the dust collec tion system before the dust separator, to direct the drill cuttings at a distance from the drill hole. This embodiment has an advantage that the aqueous drill cuttings are not allowed to slide back into the drill hole. [0020] The basic idea of an embodiment is that a suction funnel serves as at least one part of the changer unit framework such that the suction funnel is connected to at least two discharge ducts and inside the suction fun nel there is arranged a turning pipe with an opening on its flank, whereby the operating position may be selected by turning the pipe. This embodiment has an advantage that the changer unit may be implemented as a part of the suc tion funnel, and consequently no separate changer unit is needed. [0021] The basic idea of an embodiment is that an inlet duct of drill cuttings is a first connecting pipe and a discharge duct of drill cuttings is a sec ond connecting pipe and that these connecting pipes may be mutually moved such that in a first operating position there is formed a continuous duct from the first connecting pipe to the second connecting pipe, and in a second oper ating position the duct from the first connecting pipe to the second connecting pipe is cut. [0022] The basic idea of an embodiment is that the changer unit comprises a cylinder by means of which the second connecting pipe may be WO 2010/029216 PCT/F12009/050721 5 moved in relation to the first connecting pipe to the first and the second operat ing positions. This embodiment has an advantage that it provides a reliable and automatically controllable way to move the connecting pipes in relation to one another. [0023] The basic idea of an embodiment is that the second connect ing pipe is arranged in a slide structure, whereby the second connecting pipe may be moved linearly in relation to the first connecting pipe from the first op erating position to the second operating position and vice versa. This embodi ment has an advantage that the mutual movement of the connecting pipes is well controllable. [0024] The basic idea of an embodiment is that the changer unit is arrangeable between the suction funnel and the dust separator in the dust col lection system. BRIEF DESCRIPTION OF THE DRAWINGS [0025] Some embodiments of the invention are described in greater detail in the accompanying drawings, in which Figure 1 shows a schematic side view of a typical rock drilling rig and a dust collection system thereof, Figure 2 shows a schematic side view of a changer unit of the in vention arranged in a suction funnel, Figures 3a and 3b show schematic side views of an embodiment of the changer unit of the invention in two different operating positions, Figures 4a and 4b show schematic side views of a second embodi ment of the changer unit of the invention in two different operating positions, Figures 5a and 5b show schematic cross sections of a third em bodiment of the changer unit of the invention, a side view in Figure 5a and a top view in Figure 5b. [0026] For the sake of clarity, some embodiments of the invention are shown in a simplified manner in the figures. Like reference numerals refer to like parts in the figures. DETAILED DESCRIPTION OF THE INVENTION [0027] Figure 1 shows schematically a typical rock drilling rig 1 in cluding a dust collection system. Said rock drilling rig 1 comprises a mobile carrier 2, in which there may be arranged one or more movable drill booms 3. In the drill boom 3 there may be arranged a drilling unit 4, which may include at WO 2010/029216 PCT/F12009/050721 6 least a feed beam 5 and a rock drill 6. The rock drill 6 may be moved on the feed beam 5 during drilling while a percussion device included in the rock drill 6 delivers impact pulses to a tool 7. Then a drill bit 8 at the distal end of the tool 7 breaks rock and the tool 7 penetrates in the rock. In the course of drill ing, there is formed broken, partly dusty rock material that may be evacuated from the drill hole 9 by feeding from a flush medium channel 10 air, mixture of air and water or some other flush medium through the tool 7 to the drill bit 8. The flush medium pushes drill cuttings to the mouth of the drill hole, wherefrom it may be removed by means of a collection system included in the rock drilling rig 1. The rock drilling rig presented here is only one example of a typical rock drilling rig and the manner to direct drill cuttings set forth in this application may be well applied to various drilling apparatuses and systems without limiting to what is presented above. In this application, the mixture to be removed from the drill hole and containing dust, rock and other material detached from rock during drilling, as well as flush medium, water and other material possibly mix ing with rock material in the drill hole, are called drill cuttings. [0028] Typically, the dust collection system of the rock drilling rig in cludes one or more suction devices 11, wherewith it is possible to provide a necessary suction for sucking drill cuttings from a suction funnel 12 at the mouth of the drill hole 9 along a suction duct 13 to a dust separator 14. There may be one or more dust separators 14. Typically the suction duct 13 is a flexible hose. The suction funnel 12 may be a tubular piece at the upper end and lower end of which there are openings such that a tool 7 may be fitted to pass through the suction funnel 12. In the flank of the suction funnel 12 there may be at least one connecting pipe 18 or another corresponding structure to which the suction duct 13 may be connected. Further, in connection with the suction funnel 12 there may be transfer means whereby it may be displaced in relation to the feed beam 5 such that the suction funnel 12 is transferrable for the duration of drilling against the rock to be drilled such that dust will not be allowed to intrude into the environment. The dust collection system may further include at least one control unit 15, by means of which the operation of the suction device may be controlled, for instance. The travel direction of the drill cuttings in the dust collection apparatus is indicated by arrow A. [0029] In rock drilling it is possible that in some situations water leaks into the drill hole from outside the hole or through the bottom or walls of the hole. In that case the water content in drill cuttings may rise significantly.

WO 2010/029216 PCT/F12009/050721 7 Highly aqueous drill cuttings block the filters of the dust separator and they may also cause blockages in the ducts and other structures and thus jeopard ize the operation of the dust separator 14, and therefore access of such drill cuttings to the dust separator 14 should be prevented. A yet more serious problem is often posed by excessively aqueous drill cuttings that block the dust tube leading to the dust separator 14, which cannot be prevented by simply stopping the suction in the dust collection system. [0030] The solution of the invention enables selection of the direc tion of drill cuttings in the dust collection system such that drill cuttings whose composition is ordinary are directed from the drill hole 9 to the dust separator 14 by means of a dust collection system. Instead, when water content in the drill cuttings is excessive in view of the reliable operation of the dust separator, the drill cuttings are diverted to bypass the dust separator 14 away from the dust collection system, whereby blocking of both the dust separator 14 and the dust hose will be prevented. Direction of the drill cuttings may be implemented, for instance, by means of a changer unit in accordance with the invention, some embodiments of which are shown in Figures 2 to 5b. [0031] Figure 2 shows schematically a changer unit 16 of the inven tion arranged at the mouth of the connecting pipe 18 of the suction funnel 12. In the embodiment according to the figure the changer unit 16 includes a con necting part 17 wherewith a suction duct 13 may be connected to the changer unit 16. A similar changer unit is shown in Figures 4a and 4b and the operating principle of the changer unit is explained in more detail in connection with the description of said figures. In various embodiments of the invention the changer unit may also be arranged inside the actual suction funnel, as will be set forth later on in Figures 5a and 5b, or at another point in the dust collection system appropriate for the use between the drill hole 9 and the dust separator 14. [0032] Figures 3a and 3b show schematically a changer unit 16 of the invention in two different operating positions. The changer unit 16 of the figure includes a first connecting pipe 19, wherewith the changer unit 16 may be connected to the inlet line of drill cuttings, in the embodiment of Figure 2 to the connecting pipe 18 of the suction funnel 12, a second connecting pipe 20, wherewith the changer unit 16 may be connected to the discharge line of drill cuttings, in the embodiment of Figure 2 to the suction duct 13, and planar con necting and guiding pieces constituting a slide structure, wherewith the first WO 2010/029216 PCT/F12009/050721 8 connecting pipe 19 and the second connecting pipe 20 may be arranged movably to one another. In the embodiment of Figures 3a and 3b, the second connecting pipe 20 is further provided with a connecting part 17 for connection to the discharge line of drill cuttings. Further, the changer unit may include other parts necessary for the structure, operation, use and the like, such as support structures and various connecting parts. Advantageously the changer unit 16 may also include components and actuators necessary for moving the connecting pipes 19 and 20 in relation to one another for instance hydraulically or pneumatically. Advantageously the changer unit 16 may also include a con trol unit for controlling the operating positions of the changer unit 16. Advanta geously the changer unit 16 may yet include automatic detectors, such as a moisture detector 28, for automatic detection of water content in the drill cut tings. [0033] In the embodiment of Figures 3a and 3b the first and the second connecting pipes are each arranged in the planar connecting piece 22, 23 in the direction of the end surface of the pipe and the mutual movement of these connecting pieces in the direction of their interface is implemented with an actuator 24 included in the changer unit, for instance with a hydraulic or pneumatic cylinder. In the various embodiments of the invention the mutual arrangement of the first connecting pipe and the second connecting pipe movably in relation to one another may also be implemented in other manners within the scope of the claims. [0034] The changer unit of Figures 3a and 3b has two operating po sitions: the first and the second operating position. The first connecting pipe 19 is coupled fixedly to the inlet duct of drill cuttings. Whereas, the second con necting pipe 20, which is on the discharge side and coupled to the discharge duct of drill cuttings, such as suction duct 13, may be moved by means of a slide structure linearly in relation to the first connecting pipe 19 in the direction of arrow B. Depending on the structure, use environment and other factors of the rock drilling rig 1 and the dust collection system, the transfer direction B may also be other than that shown in Figures 3a and 3b, being substantially in the direction of drilling, transverse or oblique to the direction of drilling. In other embodiments of the changer unit the first and the second connecting pipe 19, 20 may also be arranged to move mutually in relation to a fixed pivot point in the direction of the rotational movement from the first operating position to the second operating position and vice versa, or the second connecting pipe 20 WO 2010/029216 PCT/F12009/050721 9 may be connected to the first connecting pipe 19 with a joint structure, by means of which the second connecting pipe 20 may be arranged in the first operating position to the mouth of the first connecting pipe 19 and away there from. [0035] In Figure 3a, the changer unit is shown in a normal operating position of the dust collection system, in which drill cuttings exiting the drill hole 9 along with a flush medium are sucked with a suction device 11 through the changer unit 16 into the dust collection system. In this operating position the first connecting pipe 19 and the second connecting pipe 20 constitute either alone or together with other components of the changer unit a continuous line that enables, on one hand, transmission of suction from the suction device 11 through the changer unit 16 to the suction funnel 12 and, on the other hand, conveyance of drill cuttings from the first connecting pipe 19 of the changer unit 16 through the second connecting pipe 20 of the changer unit 16 towards the dust separator 14. In this application document the operating position con cerned is called the first operating position. [0036] Figure 3b, in turn, shows the second operating position of the changer unit 16, in which, when water content in drill cuttings rises excessively in view of faultless operation of the dust separator, the second connecting pipe 20 is displaced from the mouth of the first connecting pipe 19 by means of an actuator 24 such that transmission of suction into the suction funnel 12 is stopped and drill cuttings will have no access to the second connecting pipe 20 and therethrough to the dust separator 14. However, as the pressure of the flush medium is sufficient to remove the drill cuttings from the drill hole 9, aqueous drill cuttings are then discharged directly from the first connecting pipe 19 or an extension thereof in the direction of arrow C outside the dust col lection system, which does not generally cause here dust problems thanks to high water content in the drill cuttings. The control of the operating positions in the changer unit may be implemented in various embodiments of the invention in the most appropriate manner, for instance, manually, with the control unit 15 of the dust collection system or with a specific control unit to be arranged in the changer unit. [0037] Figures 4a and 4b show, from different directions, schematic side views of a second embodiment of a changer unit in accordance with the invention having a structure and a principle that are very similar to those in Figures 3a and 3b and the preceding description. In this embodiment, unlike in WO 2010/029216 PCT/F12009/050721 10 the embodiment described above, the discharge side of the changer unit 16 is provided with a control part 25 by means of which the drill cuttings to be di rected to bypass the dust separator 14 are directed at a suitable distance from the drill hole 9 so that the aqueous drill cuttings will not be able, even when the drilling has ceased, to slide back into the drill hole 9 and thus to make the edges or walls of the drill hole collapse. The control part 25 may be either a rigid part arranged fixedly to the changer unit 16 or it may be a joint structure, like the connecting pipes 19, 20, whereby it is possible to couple to the changer unit 16 a separate discharge duct, such as tube or hose, which allows the aqueous drill cuttings to be directed farther away from the drill hole 9. How far away from the drill hole 9 the drill cuttings are to be directed in order to avoid problems, depends on a plurality of factors, such as drilling conditions and environment. [0038] Figures 5a and 5b show schematically a third embodiment of the changer unit in accordance with the invention, in which the suction funnel 12 of the dust collection system serves as at least one frame component of the changer unit 16. In the embodiment of the figures, the suction funnel 12 of the dust collection system is provided with at least one connecting pipe 18 that may be connected to a duct, such as suction duct 13, connected to the dust separator 14. In addition, the suction funnel 12 is then provided with at least one control part 25, by means of which drill cuttings may be directed to bypass the dust separator 14, advantageously at a distance from the drill hole. In this embodiment the operating positions of the changer unit 16 are based on a turning pipe 26 arranged inside the suction funnel 12, on the flank of which pipe there is an opening 27. This turning pipe may be turned inside the suction funnel 12 such that as the pipe is turned the opening 27 may be placed in dif ferent positions at the mouth of the connecting pipe 18 or of the control part 25. In that case the positions of the turning pipe form the at least two operating positions of the changer unit, of which the first-mentioned operating position directs drill cuttings to the dust separator 14 and the second operating position directs the drill cuttings to bypass the dust separator 14. In Figures 5a and 5b the changer unit is shown in the normal, i.e. the first operating position, in which the drill cuttings are directed through the connecting pipe 18 to the suc tion duct 13 and therefrom along the dust collection system to the dust separa tor 14.

WO 2010/029216 PCT/F12009/050721 11 [0039] In various embodiments of the changer unit, the handling method of drill cuttings and the dust collection system of the rock drilling rig in accordance with the invention it is possible to select the operating position for drill cuttings in a variety of ways. The selection of the operating position may be made by the drill operator, for instance. In that case the operator monitors water content in drill cuttings during the drilling on the sensory basis, for in stance, and as the water content is excessive in view of the operation of the dust separator 14, the operator may change the operating position of drill cut ting control. Depending on the structure and functionality of the changer unit 16 and the dust collection system a change in the operating position may be arranged for being carried out directly mechanically with structures in connec tion with the changer unit 16, with a control device intended for operating posi tion control or in some other appropriate manner. [0040] Alternatively, in various embodiments of the invention it is possible that water content monitoring of drill cuttings utilizes automatic detec tion. The manner of detection or measuring may be direct, as when using a moisture sensor, or indirect, as when using an acoustic sensor, for instance. The moisture detector 28 may be a sensor that measures water content di rectly or indirectly, such as e.g., in addition to those mentioned above, a mass flow sensor or an optic sensor, a monitoring system based on a camera or im age processing, or a combination thereof. Measurement and/or detection in formation from the moisture detector 28 may be transmitted by means of a data transmission connection 29 to the control unit of the device. The data transmission connection may be wired or wireless. [0041] In the embodiments of the invention which utilize the auto matic detection of water content in drill cuttings, also the control of the operat ing position of the changer unit 16 may be advantageously automated. In the embodiment like this, at least one upper limit value is set for the water content in the drill cuttings, the exceeding of which value prompts the drill cuttings to be directed to bypass the dust separator 14. By means of the automatically detected water content in the drill cuttings and the determined at least one limit value it is possible to control automatically the selection of the operating posi tion of the changer unit 16. The control may thus take place, for instance, by connecting the moisture detector 28 and the control of the actuator changing the operating position of the changer unit 16 to a control unit, which may be, for instance, the control unit 15 of the dust collection system, a specific, sepa- WO 2010/029216 PCT/F12009/050721 12 rate control unit of the changer unit or another available control unit. When the automatic detection of water content in drill cuttings is employed, the selection of the operating position of the changer unit 16 may also be implemented me chanically, of course. In that case, the automatic water content detection may be advantageously connected to an alarm device informing about the limit value being exceeded. In various embodiments of the invention both the limit values of the water content in drill cuttings and the operating positions of the changer unit 16 may be more than those presented above, when necessary. [0042] The above-described automatic detection of water content in drill cuttings may also be implemented separately from the method for handling of drill cuttings, the dust collection system in rock drilling and the changer unit 16 described in the present application. In these embodiments the water con tent in the drill cuttings may be implemented by direct or indirect detection of water content utilizing various sensors, camera and image processing or an other applicable method or a combination thereof as described above, but in this case the drill cuttings control is not affected on the basis of the water con tent. [0043] Instead of drill cuttings control, the water content in the drill cuttings may be utilized, when desired, only informatively by combining it, for instance, with a meter or other indicator the user may observe, with a signal or alarm to be given to the user or by making the user aware of the detected wa ter content in some other manner. In this case the user may react to the water content of the drill cuttings, depending on the situation, for instance by closing the suction in the dust collection system or by removing the suction funnel 12 from the mouth of the drill hole 9. Advantageously the information on the automatically determined water content in the drill cuttings may also be linked to the control unit 15 of the dust collection system or to another appropriate control, by means of which it is also possible to implement automatic reaction to a rise in the water content of the drill cuttings. Advantageously this may be implemented by setting at least one upper limit value for the water content in the drill cuttings, and when this value is exceeded, for instance the suction in the dust collection system is cut, the suction funnel 12 of the dust collection system is removed from the mouth of the drill hole 9 or access of drill cuttings to the dust separator 14 is otherwise automatically prevented. In addition, it is possible to react to a rise in water content in drill cuttings by controlling directly the pressure or flow of the flushing air or other drilling parameters, such as the WO 2010/029216 PCT/F12009/050721 13 impact power of the drill, the feed force or speed of the drill and the rotating pressure or speed of the drill. [0044] In some cases the features disclosed in this application document may be used as such, irrespective of other features. On the other hand, the features disclosed in this application documents may be combined, when necessary, to provide various combinations. [0045] The drawings and the related description is only intended to illustrate the inventive idea. The details of the invention may vary within the scope of the claims.

Claims

1. A method for handling drill cuttings, in which method the drill cut tings are directed away from a drill hole (9) by means of a dust collection sys tem,characterized by directing drill cuttings in the dust collection system with at least one changer unit (16) having at least a first and a second operating position and determining water content in the drill cuttings and directing the drill cuttings, according to the water content in the drill cuttings, in the first operat ing position to one or more dust separators (14) and in the second operating position away from the dust collection system before the dust separator (14).

2. The method of claim 1, c h a r a c t e r i z e d by setting at least one upper limit value for water content in drill cuttings, and the upper limit value being exceeded, selecting an operating position in which the drill cuttings are directed away from the dust collection system before the dust separator (14).

3. The method of claim 1, c h a r a c t e r i z e d by the operator of the drilling apparatus determining the water content in the drill cuttings on the sensory basis and selecting manually the operating position on the basis of the water content in the drill cuttings.

4. The method of claim 1 or 2, c h a r a c t e r i z e d by determining the water content in the drill cuttings automatically and conveying the informa tion on the water content in the drill cuttings to the operator of the drilling appa ratus, who selects the operating position manually on the basis of the water content in the drill cuttings.

5. The method of claim 1 or 2, c h a r a c t e r i z e d by determining the water content in the drill cuttings automatically and conveying the informa tion to a control unit, which selects the operating position automatically on the basis of the water content in the drill cuttings.

6. The method of claim 4 or 5, characterized by the auto matic detection employing at least one moisture detector (28).

7. The method of anyone of claims 1 to 6, characterized by directing the drill cuttings, which are directed away from the dust collection system before the dust separator (14), at a distance from the drill hole (9).

8. A dust collection system for a rock drilling rig, the system com prising at least a suction funnel (12) placed on the mouth of the drill hole, a WO 2010/029216 PCT/F12009/050721 15 suction device (11) generating suction in the system, at least one dust separa tor (14) and a duct leading from the suction funnel (12) to the dust separator (14), c h a r a c t e r i z e d by comprising at least one changer unit (16) having at least two operating positions, in the first of which operating positions there will be provided a continuous duct from the suction funnel (12) to the dust separator (14) and in the second of the operating positions there will not be provided a continuous duct from the suction funnel (12) to the duct separator (14), and consequently drill cuttings are directed away from the dust collection system before the duct separator.

9. The dust collection system for the rock drilling rig of claim 8, c h a r a c t e r i z e d by the system comprising at least one moisture detector (28) for determining water content in drill cuttings.

10. The dust collection system for the rock drilling rig of claim 8 or 9, c h a r a c t e r i z e d in that either the dust collection system or the changer unit (16) includes a control unit (15) that is arranged to select and change the operating position of the changer unit on the basis of the determined water content in the drill cuttings.

11. The dust collection system for the rock drilling rig of any one of claims 8 to 10, c h a r a c t e r i z e d by the changer unit (16) including a con trol part (25), which is arranged to direct the drill cuttings at a distance from the drill hole (9) in the second operating position of the changer unit (16), in which the drill cuttings are directed away from the dust collection system before the dust separator (14).

12. The dust collection system for the rock drilling rig of any one of claims 8 to 11, c h a r a c t e r i z e d in that the suction funnel (12) serves as at least one frame component of the changer unit (16) such that the suction fun nel (12) is connected to at least two discharge ducts and inside the suction funnel (12) there is arranged a turning pipe (26) in the flank of which there is an opening (27), and by turning the pipe it is possible to select the operating position of the changer unit (16).

13. A changer unit for directing drill cuttings, c h a r a c t e r i z e d by being arrangeable in at least two operating positions, in the first of which operating positions there will be provided a continuous duct from the inlet duct of drill cuttings to the discharge duct of drill cuttings and in the second of which operating positions the duct from the inlet duct of drill cuttings to the discharge duct of drill cuttings will be cut. WO 2010/029216 PCT/F12009/050721 16

14. The changer unit of claim 13, c h a r a c t e r i z e d in that the inlet duct of drill cuttings is a first connecting pipe (19) and the discharge duct of drill cuttings is a second connecting pipe (20) and that these connecting pipes may be moved in relation to one another such that in the first operating position there will be provided a continuous duct from the first connecting pipe (19) to the second connecting pipe (20) and in the second operating position the duct from the first connecting pipe (19) to the second connecting pipe (20) will be cut.

15. The changer unit of claim 14, c h a r a c t e r i z e d by including a cylinder (24) by means of which the second connecting pipe (20) may be moved in relation to the first connecting pipe (19) to the first operating position and to the second operating position.

16. The changer unit of claim 14 or 15, c h a r a c t e r i z e d in that the second connecting pipe (20) is arranged in a slide structure, whereby the second connecting pipe (20) may be moved linearly in relation to the fist con necting pipe (19) to the first operating position and to the second operating position.

17. The changer unit of claim 13 to 16, c h a r a c t e r i z e d in that the structure of the changer unit (16) includes at least one control part (25) that is arranged to direct the drill cuttings at a distance from the changer unit.

18. The changer unit of claim 13 or 17, c h a r a c t e r i z e d in that the changer unit (16) includes at least one connecting pipe arranged in the suction funnel (12) and connected to a duct, such as suction duct (13), con nected to the dust separator (14) and at least one control part (25), by means of which the drill cuttings are directed away from the dust collection system and a turning pipe (26) arranged inside the suction funnel (12), on the flank of which turning pipe (26) there is an opening (27) such that when the pipe is turned, the opening is located in the first operating position at the mouth of the connecting pipe (20) and in the second operating position at the mouth of the control part (25).

19. The changer unit of any one of claims 13 to 17, c h a r a c t e r i z e d by including connecting parts for arranging the changer unit (16) be tween the suction funnel (12) and the dust separator (14).

20. The changer unit of any one of claims 13 to 19, c h a r a c t e r i z e d by including at least one moisture detector (28) to be used for determin ing water content in drill cuttings. WO 2010/029216 PCT/F12009/050721 17

21. The changer unit of any one of claims 13 to 20, c h a r a c t e r i z e d in that the changer unit is coupled to a control unit included in the changer unit or to an external control unit that controls the selection and changing of the operating position of the changer unit automatically.