Patent Publication Number: US-9846020-B2

Title: Method and arrangement for providing explosive charging into a bore hole

Description:
PRIORITY 
     This application is a U.S national application of PCT-application PCT/FI2015/050249 filed on Apr. 10, 2015 and claiming priority of Finnish national application number FI 20145341 filed on Apr. 10, 2014, the contents of both of which are incorporated herein by reference. 
     TECHNICAL FIELD OF THE INVENTION 
     The invention relates to a method and arrangement for providing explosive charging into a mining or tunnelling hole, or a bore hole hereinafter. 
     BACKGROUND OF THE INVENTION 
     One of the typical explosive charging material especially for bore holes is ANFO (ammonium nitrate-fuel oil explosive), the base material of which is like a dry powder. The explosive end product can be achieved by mixing the dry powder ammonium nitrate with additive material, such as water, fuel oil or special chemicals (later additives). The mixing additionally makes ANFO sticky so to stay better in vertical up holes. Another purpose of increasing the additive is reducing dusting of dry ANFO. Usually this additive is dosed directly to an ANFO tank or right after the tank if special dosing devices are used. However, this method usually results blockages in the ANFO tank and ANFO hoses because of softened half-melted ANFO prill structure. Blockages slow down charging work and due that whole mining cycle. 
     Also other types of explosive charging materials are used, such as in site sensitized emulsion charging emulsion matrix, which is not explosive material as such, but it is sensitized to emulsion explosive by using dedicated gassing solution which is mixed to matrix. Typically the gassing solution is dosed and mixed in an early stage in process unit and then pumped through water lubricated 20-60 m long charging hose, for example, to the bore hole. 
     However when gassing solution is mixed in an early stage of emulsion line it means that gassing reaction starts to happen immediately. If for example there 15-30 min shutdown happens during the charging, the emulsion matrix in charging hoses starts to be fully sensitized to emulsion explosive. This creates great danger because detonator and primer are pushed to bore hole by same charging hose which is full of explosive material. 
     In addition problems relate also to ensuring that the materials used for explosive charging would be introduced in a desired depth in the hole and so that they would not flow to an undesired portion of the hole. The hole may be e.g. an upper hand hole, where the hole is drilled in upward direction, whereupon it must be ensured that the charging materials do not flow away from the hole. Other example is the case of a lower hand hole, where the hole is charged from above and where the charging materials should not enter into the bottom of the hole, or where there is a need to leave an empty portion into the hole and thus ensure that the charging material does not flow into the bottom or into the empty portion of the hole. 
     Previously mechanical blockages are inserted into the hole before introducing the charging materials. The mechanical blockages, such as fabric bundles are e.g. pushed by long sticks into the hole before charging the hole. This is very cumbersome and slow technique, because at first the mechanical blockage must be inserted into the hole. In addition it is difficult to push by a long stick a mechanical blockage into the hole at a certain depth, because the mechanical blockage tangles easily in the surface of the hole already before suitable location. Especially this is hard with the upper handed holes, where the mechanical blockage must be pushed in upward direction. Furthermore the pushing stick might get broken, whereupon it may be even impossible to get the broken part of the stick away from the hole. Especially all of these steps are time consuming. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to alleviate and eliminate the problems relating to the known prior art. Especially the object of the invention is to provide an arrangement and method, as well as a charging hose for ensuring that the materials used for explosive charging would be introduced and keep in a desired depth in the hole and so that they would not flow to an undesired portion of the hole. In addition the object is to perform the task easily and fast as well as in a reliable manner. An additional object of the invention is for enabling to provide explosive charging into a bore hole so that the blockages of the explosive material in the hose or danger of explosion caused by the sensitized emulsion explosive can be overcome and avoided. 
     The object of the invention can be achieved by the features of independent claims. 
     The invention relates to an arrangement providing explosive charging and a plug into a bore hole according to claim  1 . In addition the invention relates to a charging hose according to claim  20  and a method providing explosive charging into a bore hole according to claim  21 . 
     According to an embodiment of the invention the arrangement and charging hose for providing explosive charging and a plug into a bore hole, such as mining or tunnelling hole, comprises at least one first conduit advantageously arranged into the hose. According to an example the conduit as such is form by said hose. The conduit is configured to be introduced into the bore hole. In addition is it used for introducing at least one component of an explosive material to an outlet of said first conduit and thereby into said bore hole. 
     In addition the arrangement comprises also at least one plug, which is configured to be introduced into said bore hole by the help of said hose. The plug has a diameter, the size of which is configured to be manipulated after or during introducing into said bore hole at a certain depth so that after said introducing the diameter of the plug is larger than before said introducing and so that the surface of the plug after manipulation essentially make a physical contact with the bore hole surface. Moreover the plug is advantageously introduced into the hole in a releasable manner so that after or during the manipulation of the plug diameter size the plug is be released from the hose so that it stays in the bore hole essentially at said certain depth. The plug either expands so that it sticks into the hole, and/or it has material with friction coefficient so that it will be stick especially after size manipulation into the hole surface. 
     The plug advantageously comprises a (closed) volume, which can be manipulated so that the outer volume and thereby said plug diameter size increases. Therefore the plug makes a physical contact with the bore hole surface and form a mechanical blockage into the hole. The plug comprises according to an example inner and outer volumes, whereupon the diameter or outer volume of the plug can be manipulated for example by feeding a filling agent into the inner volume of the plug. The filling agent, such as pressurized air, is advantageously fed into the plug via at least one conduit of the hose. The medium filled plug advantageously stays filled without any enormous leakage after releasing. 
     The plug is according to an example coupled with the hose by a breakaway type quick release coupling, such as a bayonet coupling, but also other types of coupling means can be used, such as a tie around the plug, where the tie is configured to be broken when the plug is filled. The coupling is advantageously configured to release the plug from the hose, when the physical contact is made between the plug and the bore hole surface, and/or when the hose is pulled away from the bore hole. 
     According to an embodiment the plug may comprise compressible material or structure. As an example the plug may be a shuttlecock type bore hole plug or the like, whereupon the plug may be compressed by applying an external force before and during the introduction the plug into the bore hole. Thus, when the external force is removed after or during introducing the plug into said bore hole at the certain depth, the plug expands and sticks into the surface of the bore hole and form the blockage. 
     As an example the external force may be applied by introducing the plug into the bore hole inside a tube, sock, sleeve or the like, where the tube or the like compresses the plug during introduction. The plug can be removed or released from the tube e.g. by pushing it by a medium, advantageously e.g. by pressurized air, which is fed via at least one conduit. When the compressed plug is removed from the compression tube, the expansion of the plug diameter size is then allowed so that the plug expands and thereby sticks into the surface of the bore hole at the desired depth. 
     According to an advantageous embodiment the plug is a shuttlecock type plug or functionally similar plug. In addition the tube used for introducing said plug is advantageously a portion of at least one conduit. As an example the shuttlecock can be inserted at the opening of conduit or hose, whereupon it can be “shot” by pressurised air pulse fed via said conduit or hose, when the end of the hose is at the desired depth and before feeding the explosive material via said hose or conduit. 
     Still, according to an embodiment the plug may be provided by introducing at least one, preferably two or more chemical components so that it or they will expand after or during releasing from the hose or outlet of the conduit(s). The chemicals may be for example polyol component and polymeric component, when a hydrophobic polyurethane foam is formed when mixed. This kind of foam is tough, rigid and resistant, as well as its expansion can be controlled, whereupon it is suitable as a plug. When the mixing is performed at the outlet of the hose/conduit(s), a suitable plug, which stays in the bore hole essentially at said certain depth can be formed. 
     It is to be noted that according to an advantageous embodiment the plug can be introduced into the bore hole essentially by the same one in-out movement of the hose than used for introducing at least the component(s) of an explosive material. Advantageously the plug is provided (brought, released and/or formed) into or at the desired depth in the bore hole, whereupon the charging material(s) can be fed directly after the plug is inserted or formed into the hole. This offers huge advantages over the known prior art solutions, namely the whole plugging and charging can be done by one movement, which saves time. In addition is it very easy way to introduce said plug, because there is no need for separate instruments for pushing any initially large mechanical blockages into the hole, which can jam into the hole already before the desired depth, or even worse if they are pushed too far, it is practically impossible to pull them back into the desired depth. 
     According to an example the arrangement and charging hose comprises a charging conduit and an additional conduit both comprising inlets and outlets, respectively. The charging conduit is configured for introducing explosive base material, such as e.g. ANFO or emulsion based material to the outlet of said charging conduit. The additional conduit is configured for introducing additive material, such as e.g. water, fuel oil or special chemicals to the outlet of said additional conduit. The additive materials are used e.g. to make ANFO sticky so to stay in vertical up holes, as well as reducing dusting of dry ANFO. The additives can also be used for gassing solution used for sensitizing an emulsion explosive, for example. 
     According to an advantageous embodiment said charging conduit and additional conduit are arranged into a common hose, which can then be introduced into said bore hole so that said explosive base material and additive material are provided via said own conduits separately from each other and without any contact with each other. The explosive base material and additive material are configured to be mixed in the arrangement with each other after said outlets of said conduits in order to provide said explosive charging into the bore hole. According to an embodiment said common hose forms said charging hose. 
     Thus the additive can be brought separately to the outlet of the charging conduit and dose it directly. The mixing of the additive into the ANFO flow can thus be done using at the end portion (outlet) of the charging conduit by using a suitable ejector and nozzle, for example. This embodiment significantly decreases the blockages and due that down times in charging and whole mining cycle. 
     Relating to emulsion the sensitization of emulsion explosive can be avoided with separate additional channel and by injecting gassing solution at the late stage of process just the end portion (outlet) of the charging conduit. According to an embodiment mixer device may be arranged after gassing solution junction to properly mix the gassing solution to the base matrix. 
     The mixing of the explosive base material and additive material is advantageously arranged before the outlet of the common hose, like e.g. 1 or few meters before the outlet of the common hose so to ensure a better mixing during the end portion of the common hose. 
     According to an embodiment the arrangement and the charging hose comprises additionally a third conduit for further additional media, such as for pressurized air, for example. The third and additional conduits are advantageously arranged symmetrically into the opposite sides of the common hose in order to make the common hose more durable and stable, even if this is not compulsory. According to an embodiment the third and additional conduits are arranged at the rim portion of the common hose and the centre portion of the common hose is used as a charging conduit. The outlets at least of the charging and additional conduits are arranged before the outlet of the common hose. Also the outlet (e.g. sub-outlet) of the third conduit can be arranged before the outlet of the common hose, but according to an embodiment it can also be arranged at the outlet area of the common hose. 
     According to an embodiment the common hose (or charging hose) is configured to introduce a bore hole plugging into the bore hole. Very often downward bore holes through to a next level must be plugged before charging. Also in upward emulsion charging hole must be plugged right after charging. Otherwise charged emulsion can come down initially after charging. According to an embodiment the integrated additional or third conduits of the common hose (or charging hose) are configured to be used as a channel for introducing filling agent or other manipulating agent to dedicated bore hole plug devices, like blast air balls, so that they are able to plug the bore holes. 
     According to an advantageous embodiment the arrangement may be automatized at least partially. The hose with the plug can be introduced into the bore hole, after which the plug is released at the first predetermined depth, after which the explosive material is provided starting at the second predetermined depth. It is to be noted that the plug may be released before feeding the explosive material and/or vice versa. In addition the first plug may be released first, after which the first portion of the explosive material can be fed, next the second plug may be released at the second depth and so on. Thus, according to the invention it is possible to automatically provide the explosive material, as well as the plug(s), in suitable locations into the bore hole. 
     In addition according to an embodiment the concentration of the mixed explosive provided into the bore hole can be changed in the function of the depth so that in the first portion of the hole the provided mixed explosive has a first concentration and in the second portion of the hole the provided mixed explosive has a second concentration differing from the first one. 
     The present invention offers advantagese over the known prior art, such as by the invention great number of possible blockages can be avoided, since the ANFO is not mixed with additive until the end portion of the charging hose. In addition gassing reaction starts only at the end portion of the charging hose, which removes the danger of explosion caused by the sensitized emulsion explosive in the charging hose. In addition the common hose comprising the conduits, both the charging conduit and the additional conduit, and optionally also the third conduit, can be used with one hose manipulator and/or one hose feeder, for example, whereupon the operation of the whole charging project is very easy and fast, as well as additionally also safe maneuver. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Next the invention will be described in greater detail with reference to exemplary embodiments in accordance with the accompanying drawings, in which: 
         FIG. 1  illustrates a principle of an exemplary arrangement for providing explosive charging into a bore hole according to an advantageous embodiment of the invention, 
         FIGS. 2A-2B  illustrate examples of a charging hose for providing explosive charging into a bore hole according to an advantageous embodiment of the invention, and 
         FIGS. 3A-3B  illustrates a principle of an exemplary bore hole plug and arrangement for providing a bore hole plug into a bore hole according to an advantageous embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a principle of an exemplary arrangement  100  and  FIGS. 2A-2B  and  FIGS. 3A-3B  examples of a charging hose  101  for providing explosive charging and a plug  114  into a bore hole  102  according to an advantageous embodiment of the invention. The arrangement  100  and charging hose  101  comprises at least one first conduit  103  advantageously arranged into the hose  101 , as well as at least one plug  114 , which is be introduced into the bore hole  102  by the help of said hose. 
     As can be seen especially in  FIG. 3B  the plug  114  has a diameter, the size of which is configured to be manipulated after or during introducing the plug into the bore hole  102  at a certain depth so that after said introducing the diameter of the plug is larger than before said introducing and so that the surface of the plug after manipulation essentially make a physical contact with the bore hole surface. Moreover the plug is advantageously introduced into the hole in a releasable manner, which can be implemented e.g. by coupling the plug, such as a ball, with the hose  101  by a breakaway type quick release coupling  115 , such as a bayonet coupling. 
     The arrangement  100  and charging hose  101  comprises also according to an embodiment a charging conduit  103  and an additional conduit  104  both comprising inlets and outlets, respectively. The charging conduit  103  is configured for introducing explosive base material to the outlet of said charging conduit. The additional conduit  104  is configured for introducing additive material. 
     As can be seen in particularly in  FIGS. 2A and 2B  the charging conduit  103  and additional conduit  104  are advantageously arranged into a common hose  101  (charging hose). The charging hose  101  can then be introduced into the bore hole  102  so that the explosive base material and additive material are provided via said own conduits  103 ,  104  separately from each other and without any contact with each other. The explosive base material and additive material are mixed by a mixer device  106  with each other after said outlets of said conduits  103 ,  104  in order to provide said explosive charging  107  into the bore hole. 
     As is illustrated in  FIG. 2B  the charging hose  101  may also comprise additionally a third conduit  105  for further additional media, such as for pressurized air, for example. The third  105  and additional conduits  104  are advantageously arranged symmetrically into the opposite sides of the common hose  101 . The third  105  and additional conduits  104  are arranged at the rim portion of the common hose  101  and the centre portion of the common hose is used as a charging conduit  104 . 
     The outlets at least of the charging  103  and additional conduits  104  are advantageously arranged before the outlet  101   a  of the common hose  101 . Also the outlet of the third conduit  105  can be arranged before the outlet  101   a  of the common hose, but according to an embodiment it can also be arranged at the outlet area  101   a  of the common hose  101 . According to an embodiment, when the outlet portions of the conduits are arranged before the outlet  101   a  of the common hose  101   a , the end portion (portion after the outlets of the conduits  103 ,  104  and possibly  105 ) of the common hose  101  forms only one hose structure, where the explosive base material and additive material transferred in the mixed form. 
     According to an embodiment the arrangement comprises a mixer  106  arranged in connection with the hose. The mixer  106  is advantageously  103 ,  104 , especially when the mixer  106  is used to mix the explosive base material and additive material, like ANFO and water, fuel oil or special chemicals. According to another embodiment the mixer  106  mat located at the end (outlet  101   a ) of the common hose, especially where the mixer (or a suitable ejector and nozzle) is used for gassing emulsion. 
     According to an embodiment the arrangement may also comprise a feeding means (or feeder or pump)  108  for feeding said explosive base material and a dosing means (or dispenser)  109  configured for dosing said additive material in a certain relation with the fed explosive base material. It is to be noted that these means  108 ,  109  may also locate elsewhere in the arrangement than described in Figures, as for example in a tank  112 . The arrangement may also comprise a hose pusher  110  for pushing the hose with the plug into the mining hole  102  in a controllable manner, so for example into a desired depth before releasing the plug. The hose pusher  110 , as well as valves and feeding means or pumps are advantageously coupled with a control unit  116 , which is configured to control the feeding of the charging material(s), feeding of the hose as well as manipulation and releasing of the plug. 
     In addition the arrangement may also comprise a reel  111  for carrying the hose, where the inlet of the charging conduit is configured to be introduced into a tank  112  of explosive base material and the inlet of the additional conduit is configured to be introduced into a tank  113  of additive material. The inlet of the optional third conduit  105  is configured to be introduced into an air compressor, for example (not shown). 
       FIG. 3  illustrates a principle of an exemplary arrangement  100  for providing a bore hole plug  114  into the bore hole  102  according to an advantageous embodiment of the invention. According to an embodiment the common hose  101  (or charging hose) is configured to introduce the bore hole plugging  114  into the bore hole so that the integrated additional  104  or third conduits  105  of the common hose  101  (or charging hose) are configured to be used as a channel for introducing filling agent or other manipulating agent to dedicated bore hole plug devices  114 . The bore hole plug may be e.g. a blast air ball  114 , which is configured to expand for example and thereby to plug the bore hole  102 . Also other kinds of plugs components and otherwise suitable for using as the plug in the meaning described here are possible. 
     The hose  101  is advantageously configured to bring also the bore hole plug  114  with itself to the mining hole  102 . The outer volume of the bore hole plug is advantageously configured to be manipulated by feeding filling agent, like air or water or the like into the bore hole plug. The arrangement advantageously comprises a remote controllable valve  117  coupled between the additional or third conduit  104 ,  105  (or the hose may comprise a second additional conduit for filling agent of filling said plug) and the bore hole plug  114  located advantageously at the end portion of the hose  101 . 
     In the rest state the outer volume of the bore hole plug  114  is small, as can be seen ion  FIG. 3A , whereupon it can be fed into the bore hole  102 . When the bore hole plug is inserted into the hole  102  at the suitable level, the bore hole plug  114  may be manipulated so to change its outer volume e.g. by controlling the flow of said additional or third conduit  104 ,  105  for said bore hole plug via the remote controllable valve  117 , as can be seen in  FIG. 3B . The change of the outer volume of said bore hole plug  114  may be configured to be happened e.g. by feeding filling agent into said bore hole plug. 
     The invention has been explained above with reference to the aforementioned embodiments, and several advantages of the invention have been demonstrated. It is clear that the invention is not only restricted to these embodiments, but comprises all possible embodiments within the spirit and scope of the inventive thought and the following patent claims. For example even if the anfo or charging emulsion matrix are mentioned as the explosive base material, it is to be noted that also other suitable explosive material can also be used. The same applies also to additives and possible filling agent, they can also be selected other ways suitable for the application in question. In addition it is to be noted that also more than one plug can be introduced into the hole by same movement of the hose. For example the first plug may be coupled with the first conduit, and the second plug with the second conduit and advantageously so that they can be manipulated and released independently of each other.