WO2002042573A2 - Method and apparatus for pre-stressing a roof support - Google Patents

Method and apparatus for pre-stressing a roof support Download PDF

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Publication number
WO2002042573A2
WO2002042573A2 PCT/ZA2001/000182 ZA0100182W WO0242573A2 WO 2002042573 A2 WO2002042573 A2 WO 2002042573A2 ZA 0100182 W ZA0100182 W ZA 0100182W WO 0242573 A2 WO0242573 A2 WO 0242573A2
Authority
WO
WIPO (PCT)
Prior art keywords
settable material
stressing
support
roof
disposing
Prior art date
Application number
PCT/ZA2001/000182
Other languages
French (fr)
Other versions
WO2002042573A3 (en
Inventor
Paolo Persico
Brian Peter Lewis
Trevor Norman Clements
Neville Brian Henderson
Original Assignee
Chimica Edile Production (Pty) Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Chimica Edile Production (Pty) Limited filed Critical Chimica Edile Production (Pty) Limited
Priority to AU2002224497A priority Critical patent/AU2002224497A1/en
Publication of WO2002042573A2 publication Critical patent/WO2002042573A2/en
Publication of WO2002042573A3 publication Critical patent/WO2002042573A3/en

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D15/00—Props; Chocks, e.g. made of flexible containers filled with backfilling material
    • E21D15/58—Devices for setting props or chocks
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
    • E21D11/14—Lining predominantly with metal
    • E21D11/15—Plate linings; Laggings, i.e. linings designed for holding back formation material or for transmitting the load to main supporting members
    • E21D11/157—Laggings making use of fluid cushions, e.g. the fluid containing a hardenable material
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D15/00—Props; Chocks, e.g. made of flexible containers filled with backfilling material
    • E21D15/48—Chocks or the like
    • E21D15/483—Chocks or the like made of flexible containers, e.g. inflatable, with or without reinforcement, e.g. filled with water, backfilling material or the like

Definitions

  • This invention relates to a method and apparatus for pre-stressing a roof support.
  • a typical unit comprises a hollow sealed metal container having an inlet for pressurised fluid.
  • the inlet is provided with a non-return inlet valve and, in use, the unit is disposed between a support and a roof.
  • the unit is then inflated with pressurised fluid to fill the space between the support and the roof, thus to pre- stress the support.
  • a disadvantage of a pre-stressing unit of this type is that it has to be inflated to a substantial internal pressure (more than 14 MPa, for example) to have the desired pre-stressing effect on the support.
  • Another disadvantage of the known pre-stressing unit is that it tends to rupture at elevated pressures, i.e. at pressures approaching 60 MPa. When it ruptures, it is deflated instantaneously and this could lead to possible rock falls. The jet of fluid emanating from the rupture further presents a danger to mineworkers in its vicinity. Because the known units are designed to withstand such high pressures, they have a relatively high material specification, making them expensive.
  • a method for pre- stressing a support for a roof including the steps of: providing a hollow body; disposing a settable material in the body, the settable material being of the type which expands during setting; disposing the body between the support and the roof; and allowing the settable material to set and to expand.
  • the method may thus include the step of pre-stressing the support by the expansion of the settable material.
  • the method may include the step of pre-stressing the support by injecting pressurised fluid into the body.
  • the method may include the further step of wetting the settable material.
  • the method may include the further step of sealing the body after disposing the settable material in the body.
  • the method may include the further steps of disposing the settable material in a permeable bag and wetting the settable material prior to the steps of disposing it in the hollow body and sealing the body.
  • the settable material is wetted after being disposed in the hollow body.
  • the settable material may be wetted by introducing water to the hollow body.
  • the body is inflated by injecting pressurised water into the body.
  • the body may define an internal space for receiving the water in addition to the settable material.
  • apparatus for pre-stressing a support for a roof comprising: a hollow body disposable between the support and the roof; and a settable material disposed in the hollow body, the settable material being of the type which expands when setting.
  • the body may be sealed and may define an inlet for pressurised fluid.
  • a non- return inlet valve may be located in the inlet.
  • the body may define an internal space for receiving the settable material.
  • the body may further define free headspace adjacent the settable material for receiving a body of water.
  • the settable material referred to above may comprise inorganic particles containing mainly calcium oxide.
  • the settable material may be prepared by a method including the steps of treating particulate limestone, containing at least 90% (w/w) calcium carbonate, as follows: reducing the diameter of the inorganic particles to between 5 and 30 mm; heating the particles to a temperature of between 1500 and 1900 °C; reducing the size of the particles; and screening the particles to obtain a particle diameter of below 0.3 mm.
  • the obtained material may be mixed with suitable additives for controlling the onset and rate of the setting reaction of the material when mixed with water.
  • the additives may be selected from the group comprising super plasticisers or retarders.
  • figure 1 is a side view of a pre-stressing unit according to a first embodiment of the invention
  • figure 2 is a cross-sectional side view of the unit of figure 1 , in a pre-expanded condition
  • figure 3 is the same view as that of figure 2 with the unit in an expanded condition
  • figure 4 is a cross-sectional side view of a pre-stressing unit according to second embodiment of the invention in a pre- expanded condition
  • figure 5 is the same view as that of figure 4 with the unit in an expanded condition
  • figure 6 is a cross-sectional side view of a pre-stressing unit according to a third embodiment of the invention in a pre- expanded condition
  • figure 7 is the same view as that of figure 6 with the unit in an expanded condition
  • figure 8 is a cross-sectional side view of a pre-stressing unit according to fourth embodiment of the invention in a pre- expanded condition
  • figure 9 is the same view as that of figure
  • a pre-stressing unit according to a preferred embodiment of the invention is generally designated by reference numeral 10.
  • the unit 10 is particularly suitable for pre-stressing an elongate stick-type mine support prop 12 for supporting a roof 14 of a mine or other underground passage.
  • the unit 10 comprises a hollow body 16 having an outer pot-shaped wall 16.1 and an inner complementary shaped wall 16.2 disposed concentrically with the outer wall 16.1 and welded thereto at 16.3.
  • the body 16 defines an inner cavity 18 for receiving a settable material 20 of the type which expands on setting.
  • the settable material 20 is prepared by a method including the steps of treating particulate limestone, containing at least 90% (w/w) calcium carbonate, as follows: reducing the diameter of the inorganic particles to between 5 and 30 mm; heating the particles to a temperature of between 1500 and 1900 °C; - reducing the size of the particles; and screening the particles to obtain a particle diameter of below 0.3 mm.
  • the obtained material is mixed with suitable additives such as super plasticisers or retarders for controlling the onset and rate of the setting reaction of the material when mixed with water.
  • suitable additives such as super plasticisers or retarders for controlling the onset and rate of the setting reaction of the material when mixed with water.
  • a settable material 20 having a high expansion upon reaction with water is obtained.
  • An inlet 22 to the cavity 18 is defined by a nozzle 24 defining a passage 26.
  • a non-return inlet valve 28 is disposed in the passage 26.
  • the settable material 20 in dry powder form is disposed in the cavity 18 and the cavity 18 closed by disposing the inner wall 16.2 concentrically with the outer wall 16.1 and welding the walls together.
  • the unit 10 is disposed on top of the support 12, below the roof 14.
  • Water is injected into the cavity 18 via the inlet 22 under pressures of between 9 MPa and 15 MPa, preferably 14 MPa, to inflate the unit 10, thus to pre-stress the support 12.
  • the water mixes with the settable material 20 due to the fine particulate form of the material 20; the exothermic reaction of the material 20 with the water; and the expansion of the unit 10 when being inflated.
  • the material 20 expands when reacting with water and the volume of the material 20 thus increases to fill the cavity 18.
  • a solid body 20 capable of withstanding high pressures in excess of 60 MPa is thus defined in the cavity 18.
  • An advantage of the unit 10 is therefore that even should the wall 16.1 or 16.2 of the unit 10 rupture, the solid body 20 will not give away suddenly.
  • Another advantage of the unit 10 is that it needs to be designed to withstand a maximum internal pressure of 15 MPa and not up to 60 MPa as with the conventional units.
  • a relatively cheaper lower specification material such as a plastics material can thus be used to manufacture the body 16.
  • a pre-stressing unit according to a second embodiment of the invention is generally designated by reference numeral 10A.
  • the unit 10A is similar to the unit 10, with the exception that free headspace 18A is defined inside the unit 10A, above the settable material 20A to allow relatively better water distribution inside the unit 10A.
  • the applicants foresee that the unit 10A is injected with water at a relatively low pressure (i.e. less than 1 MPa), just enough to expand the unit 10A slightly, so that it stays in position between the support 12A and the roof 14A.
  • the material 20A expands when reacting with the water in the space 18A, thus filling the space 18A and expanding the unit 10A, to pre-stress the support 12A. It will be appreciated that relatively more reactive settable material 20A will be utilised in the case of the unit 0A as with the unit 10.
  • pre-stressing units 10A do not have to be inflated to excessive internal pressures such as those required by the known units, but that an injection pressure of approximately 1
  • the walls 16.1 and 16.2 of the units can therefore be manufactured from an even lower specification or thinner material, making these units relatively cheaper.
  • a pre-stressing unit according to a third embodiment of the invention is generally designated by reference numeral 10B.
  • the pre-stressing unit 10B is particularly suitable for use with so called matpacks 12B and comprises a rectangular envelope 16B having two opposed walls 16B.1 and 16B.2 that are welded to each other along their periphery at 16B.3.
  • the space 18B between the two walls 16B.1 and 16B.2 is filled with said settable material 20B in dry powder form.
  • the unit 10B is disposed on top of the matpacks 12B below the roof 14B and water injected into the interior 18B of the unit 10B via the inlet nozzle 24B.
  • the settable material 20B reacts with the water and expands to fill the space between the roof 14B and the matpacks 12B, to pre-stress the matpacks 12B.
  • a pre-stressing unit according to a fourth embodiment of the invention is generally designated by reference numeral 10C.
  • the pre-stressing unit 10C comprises said settable material 20C disposed in a permeable bag 16.3C.
  • the bag 16.3C is wetted and located in a hollow body 16C comprising two complementary shaped halves 16.1C and 16.2C which are movable relative to each other.
  • the settable material 20C expands as hereinbefore described to pre-stress the support prop 12C.
  • the settable material 20C is wetted after disposing the bag 16.3C in the hollow body 16.C.

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  • Engineering & Computer Science (AREA)
  • Mining & Mineral Resources (AREA)
  • Structural Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geology (AREA)
  • Mechanical Engineering (AREA)
  • Architecture (AREA)
  • Civil Engineering (AREA)
  • Tents Or Canopies (AREA)
  • Building Environments (AREA)

Abstract

This invention provides a pre-stressing unit (10) which is particularly suitable for pre-stressing an elongate stick-type mine support prop (12) for supporting a roof (14) of a mine or other underground passage. The unit (10) comprises a hollow body (16) defining an inner cavity (18) for receiving a settable material (20) of the type which expands on setting. In use, the unit (10) is disposed on top of the support (12), below the roof (14). The material (20) is wetted and when setting, the material (20) expands and the volume of the material (20) thus increases to fill the cavity (18) and pre-stresses the support prop (12). A solid body (20) capable of withstanding high pressures in excess of 60 MPa is thus defined in the cavity (18).

Description

METHOD AND APPARATUS FOR PRE-STRESSING A ROOF SUPPORT
INTRODUCTION AND BACKGROUND TO THE INVENTION
This invention relates to a method and apparatus for pre-stressing a roof support.
Various inflatable pre-stressing units for mine roof supports are known. A typical unit comprises a hollow sealed metal container having an inlet for pressurised fluid. The inlet is provided with a non-return inlet valve and, in use, the unit is disposed between a support and a roof. The unit is then inflated with pressurised fluid to fill the space between the support and the roof, thus to pre- stress the support.
A disadvantage of a pre-stressing unit of this type is that it has to be inflated to a substantial internal pressure (more than 14 MPa, for example) to have the desired pre-stressing effect on the support.
Another disadvantage of the known pre-stressing unit is that it tends to rupture at elevated pressures, i.e. at pressures approaching 60 MPa. When it ruptures, it is deflated instantaneously and this could lead to possible rock falls. The jet of fluid emanating from the rupture further presents a danger to mineworkers in its vicinity. Because the known units are designed to withstand such high pressures, they have a relatively high material specification, making them expensive.
It is known to fill a pre-stressing unit of the known type with a settable material such as cement in dry powder form. The unit is then located in position between a support and a roof and inflated with water, the idea being that the water and cement would mix so that the cement might set and provide a solid support. Unfortunately this method has failed due to the fact that the water and cement do not mix properly or at all.
It was further proposed in the past to inject quick setting cement in fluid form into such pre-stressing units. This proposal has also failed due to the difficulty in handling and injecting such quick setting cement.
OBJECT OF THE INVENTION
It is therefore an object of the present invention to provide a method and apparatus for pre-stressing a roof support with which the aforesaid disadvantages can be overcome or at least minimised.
SUMMARY OF THE INVENTION
According to a first aspect of the invention there is provided a method for pre- stressing a support for a roof including the steps of: providing a hollow body; disposing a settable material in the body, the settable material being of the type which expands during setting; disposing the body between the support and the roof; and allowing the settable material to set and to expand.
The method may thus include the step of pre-stressing the support by the expansion of the settable material.
Alternatively, the method may include the step of pre-stressing the support by injecting pressurised fluid into the body.
The method may include the further step of wetting the settable material.
The method may include the further step of sealing the body after disposing the settable material in the body.
The method may include the further steps of disposing the settable material in a permeable bag and wetting the settable material prior to the steps of disposing it in the hollow body and sealing the body.
Alternatively, the settable material is wetted after being disposed in the hollow body. The settable material may be wetted by introducing water to the hollow body.
Preferably the body is inflated by injecting pressurised water into the body.
Alternatively, the body may define an internal space for receiving the water in addition to the settable material.
According to a second aspect of the invention there is provided apparatus for pre-stressing a support for a roof, the apparatus comprising: a hollow body disposable between the support and the roof; and a settable material disposed in the hollow body, the settable material being of the type which expands when setting.
The body may be sealed and may define an inlet for pressurised fluid. A non- return inlet valve may be located in the inlet.
The body may define an internal space for receiving the settable material.
The body may further define free headspace adjacent the settable material for receiving a body of water.
The settable material referred to above may comprise inorganic particles containing mainly calcium oxide. The settable material may be prepared by a method including the steps of treating particulate limestone, containing at least 90% (w/w) calcium carbonate, as follows: reducing the diameter of the inorganic particles to between 5 and 30 mm; heating the particles to a temperature of between 1500 and 1900 °C; reducing the size of the particles; and screening the particles to obtain a particle diameter of below 0.3 mm.
The obtained material may be mixed with suitable additives for controlling the onset and rate of the setting reaction of the material when mixed with water.
The additives may be selected from the group comprising super plasticisers or retarders.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described further by way of non-limiting examples with reference to the accompanying drawings wherein: figure 1 is a side view of a pre-stressing unit according to a first embodiment of the invention; figure 2 is a cross-sectional side view of the unit of figure 1 , in a pre-expanded condition; figure 3 is the same view as that of figure 2 with the unit in an expanded condition; figure 4 is a cross-sectional side view of a pre-stressing unit according to second embodiment of the invention in a pre- expanded condition; figure 5 is the same view as that of figure 4 with the unit in an expanded condition; figure 6 is a cross-sectional side view of a pre-stressing unit according to a third embodiment of the invention in a pre- expanded condition; figure 7 is the same view as that of figure 6 with the unit in an expanded condition; figure 8 is a cross-sectional side view of a pre-stressing unit according to fourth embodiment of the invention in a pre- expanded condition; and figure 9 is the same view as that of figure 8 with the unit in an expanded condition.
DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION Referring to figures 1 to 3, a pre-stressing unit according to a preferred embodiment of the invention is generally designated by reference numeral 10. The unit 10 is particularly suitable for pre-stressing an elongate stick-type mine support prop 12 for supporting a roof 14 of a mine or other underground passage.
The unit 10 comprises a hollow body 16 having an outer pot-shaped wall 16.1 and an inner complementary shaped wall 16.2 disposed concentrically with the outer wall 16.1 and welded thereto at 16.3. The body 16 defines an inner cavity 18 for receiving a settable material 20 of the type which expands on setting.
The settable material 20 is prepared by a method including the steps of treating particulate limestone, containing at least 90% (w/w) calcium carbonate, as follows: reducing the diameter of the inorganic particles to between 5 and 30 mm; heating the particles to a temperature of between 1500 and 1900 °C; - reducing the size of the particles; and screening the particles to obtain a particle diameter of below 0.3 mm.
The obtained material is mixed with suitable additives such as super plasticisers or retarders for controlling the onset and rate of the setting reaction of the material when mixed with water. A settable material 20 having a high expansion upon reaction with water is obtained. An inlet 22 to the cavity 18 is defined by a nozzle 24 defining a passage 26. A non-return inlet valve 28 is disposed in the passage 26.
During the manufacturing of the unit 10, the settable material 20 in dry powder form is disposed in the cavity 18 and the cavity 18 closed by disposing the inner wall 16.2 concentrically with the outer wall 16.1 and welding the walls together.
In use, as shown in figure 2, the unit 10 is disposed on top of the support 12, below the roof 14. Water is injected into the cavity 18 via the inlet 22 under pressures of between 9 MPa and 15 MPa, preferably 14 MPa, to inflate the unit 10, thus to pre-stress the support 12. The water mixes with the settable material 20 due to the fine particulate form of the material 20; the exothermic reaction of the material 20 with the water; and the expansion of the unit 10 when being inflated. As shown in figure 3, when setting, the material 20 expands when reacting with water and the volume of the material 20 thus increases to fill the cavity 18. A solid body 20 capable of withstanding high pressures in excess of 60 MPa is thus defined in the cavity 18.
An advantage of the unit 10 is therefore that even should the wall 16.1 or 16.2 of the unit 10 rupture, the solid body 20 will not give away suddenly. Another advantage of the unit 10 is that it needs to be designed to withstand a maximum internal pressure of 15 MPa and not up to 60 MPa as with the conventional units. A relatively cheaper lower specification material such as a plastics material can thus be used to manufacture the body 16.
Referring to figures 4 and 5, a pre-stressing unit according to a second embodiment of the invention is generally designated by reference numeral 10A.
The unit 10A is similar to the unit 10, with the exception that free headspace 18A is defined inside the unit 10A, above the settable material 20A to allow relatively better water distribution inside the unit 10A. The applicants foresee that the unit 10A is injected with water at a relatively low pressure (i.e. less than 1 MPa), just enough to expand the unit 10A slightly, so that it stays in position between the support 12A and the roof 14A. The material 20A expands when reacting with the water in the space 18A, thus filling the space 18A and expanding the unit 10A, to pre-stress the support 12A. It will be appreciated that relatively more reactive settable material 20A will be utilised in the case of the unit 0A as with the unit 10.
It will be appreciated that an advantage of the pre-stressing units 10A is that they do not have to be inflated to excessive internal pressures such as those required by the known units, but that an injection pressure of approximately 1
MPa will suffice. The walls 16.1 and 16.2 of the units can therefore be manufactured from an even lower specification or thinner material, making these units relatively cheaper.
Referring to figures 6 and 7, a pre-stressing unit according to a third embodiment of the invention is generally designated by reference numeral 10B. The pre-stressing unit 10B is particularly suitable for use with so called matpacks 12B and comprises a rectangular envelope 16B having two opposed walls 16B.1 and 16B.2 that are welded to each other along their periphery at 16B.3. The space 18B between the two walls 16B.1 and 16B.2 is filled with said settable material 20B in dry powder form.
In use, the unit 10B is disposed on top of the matpacks 12B below the roof 14B and water injected into the interior 18B of the unit 10B via the inlet nozzle 24B. The settable material 20B reacts with the water and expands to fill the space between the roof 14B and the matpacks 12B, to pre-stress the matpacks 12B.
Referring to figures 8 and 9, a pre-stressing unit according to a fourth embodiment of the invention is generally designated by reference numeral 10C.
The pre-stressing unit 10C comprises said settable material 20C disposed in a permeable bag 16.3C. The bag 16.3C is wetted and located in a hollow body 16C comprising two complementary shaped halves 16.1C and 16.2C which are movable relative to each other. The settable material 20C expands as hereinbefore described to pre-stress the support prop 12C.
Alternatively the settable material 20C is wetted after disposing the bag 16.3C in the hollow body 16.C.
It will be appreciated that the units according to the invention are relatively easy to use and that no new handling methods will have to be taught to mineworkers.
It will be appreciated further that variations in detail are possible with a method and apparatus according to the invention for pre-stressing a mine roof support without departing from the scope of this disclosure.

Claims

1. A method for pre-stressing a support for a roof including the steps of: providing a hollow body; - disposing a settable material in the body, the settable material being of the type which expands during setting; disposing the body between the support and the roof; and allowing the settable material to set and to expand.
2. A method according to claim 1 which includes the further step of pre- stressing the support by the expansion of the settable material.
3. A method according to claim 1 or claim 2 which includes the further step of pre-stressing the support by injecting pressurised fluid into the body.
4. A method according to any one of claims 1 to 3 which includes the further step of wetting the settable material.
5. A method according to any one of the preceding claims which includes the further step of sealing the body after disposing the settable material in the body.
6. A method according to claim 5 which includes the further steps of disposing the settable material in a permeable bag and wetting the settable material prior to the steps of disposing it in the hollow body and sealing the body.
7. A method according to claim 5 which includes the further steps of disposing the settable material in a permeable bag and wetting the settable material after the steps of disposing it in the hollow body.
8. A method according to claim 7 wherein the settable material is wetted by introducing water to the hollow body.
9. A method according to claim 8 wherein the body is inflated by injecting pressurised water into the body.
10. A method according to claim 9 wherein the body defines an internal space for receiving the water in addition to the settable material.
11. A method according to any one of the preceding claims wherein the settable material comprises inorganic particles containing mainly calcium oxide.
12. A method according to claim 11 wherein the settable material is prepared by a method including the steps of treating particulate limestone, containing at least 90% (w/w) calcium carbonate, as follows: - reducing the diameter of the inorganic particles to between
5 and 30 mm; heating the particles to a temperature of between 1500 and 1900 °C; reducing the size of the particles; and - screening the particles to obtain a particle diameter of below 0.3 mm.
13. A method according to claim 12 wherein the obtained material is mixed with suitable additives for controlling the onset and rate of the setting reaction of the material when mixed with water.
14. A method according to claim 13 wherein the additives are selected from the group comprising super plasticisers and retarders.
15. A method for pre-stressing a support for a roof substantially as herein described with reference to the accompanying drawings.
16. Apparatus for pre-stressing a support for a roof comprising a hollow body disposable between the support and the roof; and a settable material disposed in the hollow body, the settable material being of the type which expands when setting.
17. Apparatus according to claim 16 wherein the body is sealed and defines an inlet for pressurised fluid.
18. Apparatus according to claim 17 wherein a non-return inlet valve may be located in the inlet.
19. Apparatus according to any one of claims 16 to 18 wherein the body defines an internal space for receiving the settable material.
20. Apparatus according to claim 19 wherein the body further defines free headspace adjacent the settable material for receiving a body of water.
21. Apparatus according to any one of claims 16 to 20 wherein the settable material comprises inorganic particles containing mainly calcium oxide.
22. Apparatus according to claim 21 wherein the settable material is prepared by a method including the steps of treating particulate limestone, containing at least 90% (w/w) calcium carbonate, as follows: - reducing the diameter of the inorganic particles to between
5 and 30 mm; heating the particles to a temperature of between 1500 and 1900 °C; reducing the size of the particles; and - screening the particles to obtain a particle diameter of below 0.3 mm.
23. Apparatus according to claim 22 wherein the obtained material is mixed with suitable additives for controlling the onset and rate of the setting reaction of the material when mixed with water.
24. Apparatus according to claim 23 wherein the additives are selected from the group comprising super plasticers and retarders.
25. Apparatus for pre-stressing a support for a roof substantially as herein described and as illustrated in the accompanying drawings.
PCT/ZA2001/000182 2000-11-21 2001-11-21 Method and apparatus for pre-stressing a roof support WO2002042573A2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2002224497A AU2002224497A1 (en) 2000-11-21 2001-11-21 Method and apparatus for pre-stressing a roof support

Applications Claiming Priority (2)

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ZA200004280 2000-11-21
ZA2000/4280 2000-11-21

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WO2002042573A2 true WO2002042573A2 (en) 2002-05-30
WO2002042573A3 WO2002042573A3 (en) 2003-02-20

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105350990A (en) * 2015-11-25 2016-02-24 安徽理工大学 Mining support having double pressure indicating function
WO2020211107A1 (en) * 2019-04-18 2020-10-22 东北大学 Artificial ore pillar for underground support and construction method therefor

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US4481037A (en) * 1982-06-24 1984-11-06 Fosroc International Limited Cement compositions
US5143340A (en) * 1989-05-30 1992-09-01 Fosroc International Limited Load support
US5435670A (en) * 1992-07-03 1995-07-25 Hl&H Timber Products (Proprietary) Limited Spacer assembly and method
US5454866A (en) * 1992-06-23 1995-10-03 H L & H Timber Products (Pty) Ltd. Grout composition
WO2000011318A1 (en) * 1998-08-24 2000-03-02 Grinaker Construction Limited Apparatus for prestressing a support in underground mining
WO2000011319A1 (en) * 1998-08-24 2000-03-02 Grinaker Construction Limited Method of and apparatus for prestressing a support in underground mines

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GB2058037A (en) * 1980-08-15 1981-04-08 Coal Industry Patents Ltd Compositions for stowing cavities
US4481037A (en) * 1982-06-24 1984-11-06 Fosroc International Limited Cement compositions
US5143340A (en) * 1989-05-30 1992-09-01 Fosroc International Limited Load support
US5454866A (en) * 1992-06-23 1995-10-03 H L & H Timber Products (Pty) Ltd. Grout composition
US5435670A (en) * 1992-07-03 1995-07-25 Hl&H Timber Products (Proprietary) Limited Spacer assembly and method
WO2000011318A1 (en) * 1998-08-24 2000-03-02 Grinaker Construction Limited Apparatus for prestressing a support in underground mining
WO2000011319A1 (en) * 1998-08-24 2000-03-02 Grinaker Construction Limited Method of and apparatus for prestressing a support in underground mines

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105350990A (en) * 2015-11-25 2016-02-24 安徽理工大学 Mining support having double pressure indicating function
WO2020211107A1 (en) * 2019-04-18 2020-10-22 东北大学 Artificial ore pillar for underground support and construction method therefor

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