Claims
- 1. A stemming device for holes which device comprises a generally cylindrical object formed of a solidified material selected from a group consisting of natural rubber, synthetic rubbers and plastic materials having a generally circular top and bottom and a lateral surface corrugated to form a series of frustrated cones, a series of O-rings placed in the corrugations of the lateral surface, said device being capable of forming a seal in conjunction with the wall of a hole and being characterized in that it prevents, minimizes or substantially retards the flow of flowable, pourable or pumpable material from said hole when said device is moved in the direction opposite that of insertion whereby the O-rings expand and form a seal between the device and the wall of said hole.
- 2. A stemming device for effectively sealing holes comprising:
- a resilient member having front, lateral and rear surfaces and comprised of a resistant solidified foam material,
- reinforcing means attached to said member for reinforcing said member,
- wherein the lateral surface is in contact with the wall of said hole and said rear surface is provided with an inwardly and rearwardly tapered trailing surface defining a flexible edge which remains in contact with the wall of said hole and adapted to flex toward the wall of said hole when a force is applied to the front surface of said device from within the hole which would tend to move said device rearwardly out of said hole in the direction of said rear surface,
- wherein said resilient member comprises an outer shell and wherein said reinforcing means comprises a hollow core secured within said outer shell,
- wherein said hollow core is in the form of a tube having front and rear ends, said front end being closed and said rear end being open and extending through to said rear surface thereby defining an opening within the interior of said device, and
- wherein said front end of said tube forms a portion of said front surface of said device, wherein said front end is provided with a one-way valve adapted to allow gas within the hole head of said device to be discharged through said device and out of the hole.
- 3. A stemming device for effectively sealing holes comprising:
- a resilient member having front, lateral and rear surfaces and comprised of a resistant solidified foam material,
- reinforcing means attached to said member for reinforcing said member,
- wherein the lateral surface is in contact with the wall of said hole and said rear surface is provided with an inwardly and rearwardly tapered trailing surface defining a flexible edge which remains in contact with the wall of said hole and adapted to flex toward the wall of said hole when a force is appliecd to the front surface of said device from within the hole which would tend to move said device rearwardly out of said hole in the direction of said rear surface,
- wherein said resilient member comprises an outer shell and wherein said reinforcing means comprises a hollow core secured within said outer shell,
- wherein said hollow core is in the form of a tube having front and rear ends, said front end being closed and said rear end being open and extending through to said rear surface thereby defining an opening within the interior of said device, and
- wherein said lateral surface which is corrugated so as to form a series of frustrated cones, a series of O-rings placed in said corrugations formed in the lateral surface of said outer shell whereby the O-rings form the seal between said device and the wall of said hole.
Priority Claims (2)
| Number |
Date |
Country |
Kind |
| 2604/70 |
Sep 1970 |
AU |
|
| 4561/71 |
Apr 1971 |
AU |
|
Parent Case Info
This is a continuation of application Ser. No. 181,161 filed Sept. 16, 1971 and now abandoned.
This invention relates to stemming or sealing devices and to a method of stemming holes; in particular it relates to a method of stemming "up-holes." By "up-holes"we mean those holes of the kind in which the toe of the hole is located higher in relation to the work face than the collar of the hole.
In underground mining operations it is frequently desirable to blast away rock from the walls and ceiling of the workings. This entails drilling holes in the work face at inclinations above the horizontal -- i.e., in an upward direction -- and hereinafter such holes will be referred to as up-holes. Commonly the blasting agent used in such holes is ammonium nitrate impregnated with fuel oil, for example `ANFO,` which is pneumatically injected into the holes so that it forms a compact mass which stays in the holes even if they are vertical up-holes.
However, ammonium nitrate/fuel oil blasting agents are not waterproof nor are they very powerful in relation to other explosives. The so-called slurry explosives are, in general more waterproof and more powerful than the ammonium nitrate/fuel oil compositions, and for these reasons it is desirable to use them in blasting operations in up-holes. By slurry explosive we mean, any explosive composition which is capable of being flowed, pumped or poured. Most commonly slurry explosives are aqueous compositions comprising ammonium nitrate, a gelling agent an organic fuel and a metal fuel. A typical composition is for example:
Further, when the borehole was not completely filled with slurry explosive but rather the slurry column terminated some distance from the collar of the hole it was found to be difficult to locate a suitable stemming device in the borehole.
We have now found new stemming devices for holes and a method of stemming a borehole wherein the desired compositions contained therein are retained in the hole. Our stemming devices and methods are applicable to all boreholes. Thus our devices and methods may be used in holes drilled in a downward direction from the work face and thus in addition prevent the ingress of unwanted matter, for example water, into the hole. However, they are particularly useful in stemming up-holes. Our method is of general application to retain the contents of a hole in a desired position. Not only is it useful for applications relating to blasting explosives, but it can be applied to procedures involving the containment of any flowable, pourable or pumpable material in a confined space having an open end. Thus for example grouting materials such as cement mixtures in their flowable state can be retained in a position in upholes by means of our stemming device and process until the grouting has aquired sufficient rigidity to become self-supporting.
Accordingly we provide a stemming device for holes which device comprises at least one layer of a resilient material capable of forming a seal in conjunction with the wall of a hole said seal being characterized in that it prevents, minimizes or substantially retards the flow of flowable, pourable or pumpable material from the hole.
The resilient material from which our device may be fabricated may comprise for example, natural rubber, synthetic rubbers, cork or plastics materials. The plastics materials include polymers such as, for example, polyethylene, polypropylene, polymethylpentene-1, polyvinylchloride, polyesters, polysiloxanes, polyamides, polyacrylamides, polybutadiene, polyacrylonitrile, polyurethanes, and copolymers thereof. Other suitable materials, although less preferred as polystyrene, urea-formaldehyde resins and phenol-formaldehyde resins. If desired the resilient material may contain other additives well known in the art for example fillers, extenders, stabilizers, antioxidants, plasticizers, softening agents, flame retardants, colouring materials and the like.
The stemming materials may be prefabricated into shapes designed to fit into appropriate sizes and shapes of holes. Thus they may be in solid blocks, in sheets of various thicknesses or in the form of threaded screws. Alternatively they may be in the form of foamed shapes. Such foams may conveniently be of a size larger than the space that they have to fill in the hole, so that they may be constrained prior to insertion into the hole and then after insertion and removal of the constraining means allowed to expand so as to form a tight seal against the wall of the hole. It is also convenient to form foamed materials in situ by foaming plastics materials in the hole in the conventional manner. A typical example of forming a foamed stemming material in situ is the preparation of a polyurethane foam which may be injected into the hole as a semifluid mass which subsequently sets in the hole to form a foamed stemming material. Alternatively the stemming material may be made from two materials which react one with the other with the evolution of a gas to form a solid. The two liquids are contained separately in a capsule. Immediately prior to insertion of the capsule into the hole the membrane separating the materials in the capsule is ruptured and the ingredients are allowed to mix. The capsule is inserted in the hole, the reaction product causes the capsule to burst and the resultant reaction product on leaving the capsule forms a stemming material in the hole.
A preferred stemming, tamping or hole sealing device is a prefabricated shaped object comprising resilient material, as hereinbefore described, and at least one reinforcing member. Such a hole sealing device may have a reinforcing member or a series of reinforcing members located internally within the shaped resilient material or alternatively such members may be attached to the exterior surface of the resilient material. Yet again such members may be located partially within the shaped resilient material and extend beyond its exterior surface. By reinforcing member we mean a member which is less resilient than the resilient material from which the shaped object is made. The shape of the reinforcing member or members is not narrowly critical but the shape chosen for any particular device should be such that the reinforcing member enhances the strength of a seal made between the device and the wall of a hole into which the device has been placed. The reinforcing material may be for example in the form of rigid rods, tubes or strips which may be solid or hollow and made for example, from metal, plastics material or rubber; they may also take the form of rubber 0-rings or be screws made from hardened rubber or semirigid plastics materials. It is further preferred that the stemming, tamping or hole sealing device be provided with means for example a one way valve, through which gas, for example air, may pass. Such a means facilitates the insertion of the device into a hole which is closed at one end. Such means allows the gas in the hole to escape from the hole instead of being compressed as the device is inserted into the hole. Our preferred device comprising at least one reinforcing member is suitable for processes hereinbefore described but wherein the device did not comprise a reinforcing member. The inclusion of one or more reinforcing members in our device is advantageous in that it facilitates the insertion of the device into the desired position in a hole. Thus for example when the resilient material is a foamed plastics material and the reinforcing member is a rigid hollow tube, the device may be urged into a hole by applying a force to the rigid hollow tube in the direction in which it is desired to propel the device. Furthermore the presence of a reinforcing member in the device assists in providing an enhanced seal between the wall of the hole and the device by providing areas of differing resilience in the device. Typically there may be mentioned a device comprising a resilient plug surrounding a rigid core. We have observed with devices of this type when such a device is inserted in one direction into a hole of smaller dimensions that the unconstrained device and then a force is applied to said device which tends to move said device in a direction opposite to the direction of insertion that the more resilient portions of the device roll up on themselves to form a seal having great stability between the device and the wall of the hole.
The reinforced devices of this embodiment may, as hereinbefore described for devices having no reinforcement be prefabricated into shapes designed to fit into appropriate sizes and shapes of holes and preferably being larger than the space that they have to fill in the hole. Thus such devices may be of regular shape for example in the form of a cube, parallelpiped, pyramid, frustrum of a pyramid, polyhedron, cone, ellipsoid, cylinder or truncated cylinder. Less preferred shapes are a sphere or spheroid. Alternatively there may be of irregular shape designed to occupy the desired space for a particular purpose. It is often convenient to provide our devices with a tapered or pointed section, which may be regularly or irregularly shaped. Such a section is useful when it is the first part of the device to be urged into a hole and facilitates the positioning of the device. It is also convenient for some purposes to provide our device with a tapered section such that portion of the device, particularly that portion which is to be located nearest the collar or orifice of a hole, is wider than the remainder of the device. A further convenient form of our device is one in which the exterior surface is corrugated. Such a configuration provides a series of seals with the wall of a hole and is very convenient when used in conjunction with exterior located 0-rings as reinforcing members.
More than one stemming material may be used to form our device. Thus it may be convenient to use a sheet of material as a primary material in proximity to the contents of the hole, and then to have a further material, for example, a foamed plastics material, in the hole as a further stemming material. Alternatively it may be convenient to have a series of stemming materials, such as sheets or reinforced preformed foams attached to a common axis and to insert the assembly into the hole so as to form a series of seals with the wall of the hole. Such an assembly is advantageous in instances where the borehole is rough and the individual seals so formed are not completely effective against the flow of material from the hole, although the seals in combination are effective in preventing, minimizing or substantially retarding the flow of material from the hole.
Accordingly we also provide a process of stemming a hole which process comprises inserting into or forming in a hole at least one stemming device as hereinbefore described, in a manner such that said stemming device forms a seal in conjunction with the wall of said hole capable of preventing minimizing or substantially retarding the flow of flowable, pourable or pumpable material from said hole.
By the use of our stemming device holes may be charged with any flowable, pourable or pumpable composition, which may be for example a liquid or a mixture of liquids, solid material in divided form or a slurry of solid and liquid materials, and the charge contained or substantially contained within the hole by stemming the charged hole with at least one of our stemming devices.
Accordingly we provide a process of charging a hole with a flowable, pourable or pumpable composition which process comprises in combination loading a hole with said flowable, pourable or pumpable composition and stemming said hole with at least one stemming device as hereinbefore described in a manner such that said stemming device forms a seal in conjunction with the wall of said hole capable of preventing, minimizing or substantially retarding the flow of said compositions from said hole.
In particular our stemming device is useful in mining operations and may be used in the preparation of boreholes containing explosive compositions.
Accordingly we provide a process of charging a hole with at least one explosive composition which process comprises in combination loading a hole with said explosive commposition and stemming said hole with at least one stemming device as hereinbefore described in a manner such that said stemming device forms a seal in conjunction with the wall of said hole capable of preventing, minimizing or substanttially retarding the flow of said explosive composition from said hole. Such a process is particularly suited for loading up-holes such as are encountered in underground mining operations.
This process is applicable to holes containing any type of explosive material and more than one type of explosive material may be present in the hole. Thus for example it may be desirable, because of the nature of the material being blasted, to have explosive materials of differing compositions present in the hole. Such compositions could be for example a series of ammonium nitrate slurry compositions of varying explosive power; alternatively the compositions could comprise a slurry explosive and an ammonium nitrate-fuel oil composition or an explosive based on nitroglycerine. The amount of stemming material used and its position in the hole will depend on the conditions under which it is being used and the type of blasting result being desired. Thus for example the hole may be filled substantially with an explosive composition and the stemming material may occupy only a minor proportion of the hole and be situated substantially in the vicinity of the collar of the hole. Alternatively, because of the nature of the blasting operation being performed, it may be desirable to have the explosive composition located at some distance from the work face. Under such conditions the stemming material may be used to retain the explosive composition in the desired position. Again it may be desirable to locate the explosive charge in more than one position in the hole. Under these circumstances the stemming material may be used as a spacing material between the separated charges in addition to acting as a stemming material in the vicinity of the collar of the hole. It is sometimes found in drilling a hole that cracks or fissures are intersected during the drilling operation and that water flows from these cracks or fissures into the borehole. The presence of such water during a blasting operation is undesirable and our stemming material may be utilized to minimize or prevent such water flow. Thus for example it may be found that such a wet fissure occurs in the vicinity of the toe of the hole and it is convenient to staunch the water flow by locating our stemming material in the vicinity of the toe of the hole and the fissure prior to loading the hole with the desired explosive material. Further stemming material would then be used in the hole as described above for locating the explosive material and stemming the hole. In charging a hole with an explosive composition it is usually convenient to position the charge in the hole and then stem the hole with our stemming material. However it is sometimes convenient to partially stem the hole prior to the introduction of the explosive material and then to complete the stemming of the hole subsequent to the completion of the introduction of the explosive material into the hole. Thus for example a hole may be stemmed in part by a stemming material, for example a foamed plastic material, situated in the vicinity of the collar of the hole and extending some distance into the hole. A loading hose may be inserted through the stemming material by means of an orifice in the stemming material and of sufficient size to allow the passage of the loading hose through it. A fluid explosive composition, such as an explosive slurry, may then be pumped into the hole through the hose. After the explosive composition has been charged into the hole, the loading hose may be withdrawn and the orifice sealed with further stemming material which may be the same as or different from the original stemming material. Stemming materials used in our process of charging holes with explosive compositions may be the resilient materials described above. We have found plastics materials to be very useful for this purpose particularly foamed plastics materials such as foamed polyurethane compositions. Such foamed plastics materials may be preformed and inserted into the hole as a plug or alternatively they may be formed in situ in the hole.
Explosive compositions in holes which have been charged with explosive compositions by the procedure described above may be detonated using conventional primers and detonating devices. Thus for example the priming charge, with detonating means attached, may be seated in the leading face of the stemming material situated in the vicinity of the collar of the hole. Alternatively the explosive composition may be primed at the toe of the hole or at one or more points along the explosive charge by inserting the primer, with detonating means attached, into the hole in the course of the charging operation. Yet again if there is more than one section of stemming material in the hole, primers and detonating means may be attached to any one of or all of these stemming materials. When the stemming material is in the form of a preformed object having an internal orifice it is sometimes convenient to locate and attach suitable primers and detonating devices within such an orifice. Such a procedure has application when explosive compositions are stemmed in a series of holes by means of preformed objects according to our invention and the compositions are then detonated by the well known techniques of delay firing. This procedure of locating primers and detonating devices ensures that they are held in position during the detonating sequence and thus the possibility of misfires is reduced. Detonation of the explosive compositions is obtained in the conventional manner.
Our stemming materials may also be used on construction sites where it is desired to confine building materials such as cement slurries in positions for a period of time. They are particularly useful where it is desirable to incorporate cement in the roof of a building or in the overhead portions of a tunnelling construction.
Accordingly we provide a process of construction which process comprises in combination charging a hole with a flowable, pourable or pumpable building material and stemming said hole with at least one stemming device as hereinbefore described in a manner such that said stemming device forms a seal in conjunction with the wall of said hole capable of preventing, minimizing or substantially retarding the flow of said building material from said hole. Such a process is particularly suited for charging up-holes.
Our stemming devices are also useful in that they may be used as a means of sealing and anchoring bolts, pins and the like into holes formed in solid surfaces. Thus for example they may be used to hold bolts in the rock roof of a tunnel or a mine or yet again they may be used to hold pins and hooks inserted in holes made in house walls, said pins and hooks being used to display ornaments, pictures and the like. For use as a sealing and anchoring device we have found it convenient for most purposes to use preformed shaped articles comprising a resilient foamed material such as foamed rubber or a plastic foam for example foamed polyethylene, polypropylene, polymethylpentene-1 or nylon. Where the hole to be sealed is small it is sometimes more convenient to use a resilient foam formed in situ in the hole. In the instance where a preformed shaped device is used it is convenient to choose a shape which approximates to the shape of the hole to be sealed. For example where a bolt or pin is to be held in a hole of circular cross section, it is convenient to use a preformed right cylinder as the sealing device. It is preferred to use preformed shaped devices of the reinforced type, particularly those devices comprising an internal reinforcing member.
Accordingly we provide a process of sealing and anchoring a supporting member in a hole formed in a solid surface which process comprises inserting into said hole an assembly comprising in combination at least one preformed shaped resilient stemming or sealing device as hereinbefore described and provided with a hollow reinforcing member extending internally and substantially axially along the longest dimension of said device, said reinforcing member being optionally threaded in part and being attached at one end to a plate or nut which may optionally be threaded and situated externally of said device and a threaded supporting member inserted into a backing plate situated externally of said device and then inserted into said hollow reinforcing member so as to be engageable with said threaded reinforcing member, plate or nut; engaging said supporting member in said threaded reinforcing member, plate or nut, so as to compress said sealing device and thereby forming a seal between the wall of said hole and said device sufficient to seal and anchor said supporting member in said hole.
The hollow reinforcing member is preferably made of metal and attached to the plate or nut by suitable means for example welding. Whilst the adhesion between the reinforcing member and the internal surface of the device is often quite adequate, it is sometimes advantageous to use a coating of adhesive between the reinforcing member and the device to improve the adhesion between them. The assembly should be inserted into the hole in a manner such that the threaded plate or nut is the component of the assembly closest to the toe of the hole prior to engaging the thread of the supporting member in the plate or nut. However sufficient space should be left between the toe of the hole and the plate or nut to enable the supporting member to be adequately threaded into the plate or nut without encountering the surface at the toe of the hole. The backing plate should be situated in the vicinity of the collar of the hole and preferably should be located external of the hole so that in part it can be made to touch and extend some distance along the surface into which the hole has been formed. This embodiment of our invention is advantageous in that it provides a means of anchoring supporting members in surfaces without embedding a part of such members in the surfaces as taught in the prior art. Anchoring costs are thereby reduced.
Our stemming materials may also be used for the purposes of safety particularly from the aspect of controlling fires or dust in mines. Thus the collar of a hole may be stemmed with our materials. The hole, in this case an up-hole, is filled with a fire extinguishing material such as water, sand or a solid chemical fire extinguishing material such as "Monnex" (Registered Trade Mark). In a time of a fire emergency, the stemming material -- previously connected to a rupturing device -- is dislodged and the fire extinguishing material is distributed over the fire.
Accordingly we provide a process of controlling a fire which process comprises in combination charging an up-hole with at least one fire extinguishing material, stemming said hole with at least one stemming device as hereinbefore described in a manner such that said stemming device forms a seal in conjunction with the wall of said hole capable of preventing, minimizing or substantially retarding the flow of said fire extinguishing material from said hole, rupturing and dislodging said stemming material and distributing said fire extinguishing material over and in the vicinity of a fire.
Our preferred stemming, tamping or hole sealing device comprising a shaped resilient material and at least one reinforcing member may, like its unreinforced counterpart, be used to stem, tamp or seal holes of various shapes and dimensions. Such a device may be used for example to seal boreholes containing explosive compositions. Such holes may be of various diameters for example holes of diameters in the range from 1/2 to 12 inches. Such a device is particularly useful in "upholes" of diameter in the range from 1 to 4 inches for example 2 inches. It is particularly useful since, because of its construction, it has the property of strengthening the seal between the device and the wall of the hole when a load, for example from a column of explosive material, is applied to it in a direction opposite to the direction of insertion of the device into the hole.
Accordingly we provide a process of stemming, tamping or sealing a hole which process comprises inserting into a hole at least one device comprising resilient material as hereinbefore described shaped so that its maximum transverse unconfined dimension is equal to or greater than the maximum transverse dimension of the hole to be stemmed, tamped or sealed and at least one reinforcing member as hereinbefore described said device being characterized in that when said device is moved in the direction opposite to the direction of insertion the resilient portion of said device is compressed upon itself to strengthen the seal between said device and the wall of said hole so as to counteract the movement of said device.
When the stemming device is in the form of a prefabricated shaped object having an orifice within the interior we have found that such an orifice, in addition to be useful for urging the device into the desired position or locating reinforcing members, is suitable as a repository for articles used in various processes. Thus for example such an orifice in the absence of a reinforcing member or in the presence of a hollow reinforcing member within it is useful in explosive applications for the location of detonating means for example explosive initiating charges such as pentolite and detonators. It will be appreciated that in the instance where the detonating means is located in a borehole containing explosive slurry there is the possibility that the slurry will contaminate the detonating means. By locating the items in the orifice of the stemming device such contamination is reduced substantially and usually eliminated.
Accordingly we provide in the known process of locating within a borehole detonating means suitable for the detonation of an explosive composition located within said borehole the improvement which comprises locating said detonating means within the interior of a prefabricated shaped stemming device as hereinbefore described situated in said borehole.
In another example reference may be made to the location of dust suppressants in the orifice of the stemming device. It has been common practice in mining operations to use various materials to suppress dust in the work area in the region of a blast hole after the explosive material has been detonated. Typical of dust suppressants in common use there may be mentioned water and materials in the form of gels, for example cellulose gels and sodium silicate gels. Hitherto such dust suppressants have been located at or in the proximity of the collar of a blast hole and when such holes are inclined upwardly it has been found difficult to locate such suppressants, usually in the form of a container or a package, in a suitable and stable position. We have now found that a very convenient way of locating such suppressants is to insert them in the orifice of our stemming devices.
Accordingly we provide in the known process of locating within a borehole dust suppressant means the improvement which comprises locating said dust suppressant means within the interior of a prefabricated shaped stemming device as hereinbefore described situated in said borehole.
US Referenced Citations (8)
Continuations (1)
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Number |
Date |
Country |
| Parent |
181161 |
Sep 1971 |
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Patent Grant
3952656
