TRANSPORT OF EXPLOSIVES

Abstract

A method of vertically transporting emulsion explosive includes, using a pump, pumping a predetermined volume of emulsion explosive, from an emulsion explosive reservoir, into a vertically extending pipe, wherein pumping is effected airtightly at least between the pump and a downstream end of a volume of emulsion explosive that has been pumped into the vertically extending pipe for at least a part of the travel of emulsion explosive of the predetermined volume of emulsion explosive down the vertical pipe.

Claims

1. A method of vertically transporting emulsion explosive, the method including, using a pump, pumping a predetermined volume of emulsion explosive, from an emulsion explosive reservoir, into a vertically extending pipe, wherein pumping is effected airtightly at least between the pump and a downstream end of a volume of emulsion explosive that has been pumped into the vertically extending pipe for at least a part of the travel of emulsion explosive of the predetermined volume of emulsion explosive down the vertical pipe.

2. The method according to claim 1, wherein airtight pumping is effected between the emulsion explosive reservoir and the downstream end of a volume of emulsion explosive that has been pumped into the vertically extending pipe for at least a part of the travel of emulsion explosive of the predetermined volume of emulsion explosive down the vertical pipe.

3. The method according to claim 1, wherein the vertically extending pipe is open to the atmosphere at a downstream end thereof.

4. The method according to claim 1, wherein the vertically extending pipe is closed to the atmosphere at its downstream end, being configured for positive pressure to be applied to the downstream end of the predetermined volume of emulsion explosive, or part thereof, from the downstream end of the vertically extending pipe, as the predetermined volume of emulsion explosive, or part thereof, is travelling along the vertically extending pipe.

5. The method according to claim 1, wherein the vertically extending pipe extends vertically for a vertical distance beyond 500 m.

6. The method according to claim 1, wherein the emulsion explosive is unsensitised emulsion explosive, and the method includes sensitising the emulsion explosive downstream of a downstream end of the vertically extending pipe.

7. The method according to claim 1, wherein pumping is be effected at a velocity equal to the velocity of the predetermined volume of emulsion explosive when moving in the vertically extending pipe solely under gravity.

8. The method according to claim 1, wherein pumping is effected at a velocity higher than the velocity of the predetermined volume of emulsion explosive when moving in the vertically extending pipe solely under gravity.

9. The method according to claim 1, wherein pumping continues until the predetermined volume of emulsion explosive has passed through the pump.

10. The method according to claim 1, wherein the predetermined volume of emulsion explosive is sufficient for movement thereof along the pipe to continue after pumping has been discontinued, under force of gravity and against vacuum formed between an upstream end of the predetermined volume and the pump.

Description

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

[0036] THE INVENTION WILL NOW BE DESCRIBED IN MORE DETAIL in terms of an exemplary embodiment, with reference to the accompanying diagrammatic drawings in which FIG. 1 shows an installation according to the invention, installed at an underground mining operation, and FIGS. 2 to 7 show various stages of operation of two embodiments of the installation.

[0037] Referring to the drawings an more specifically fir FIG. 1, reference numeral 10 generally indicates an underground mining operation that includes a mine shaft 15 that has been sunken into a body of earth through a surface 13 of the body of earth.

[0038] The mining operation 10 includes an installation 11 according to the invention.

[0039] The installation 11 includes a primary emulsion explosive reservoir 12 that contains non-sensitised, bulk emulsion explosive.

[0040] The primary reservoir 12 has an outlet 14, from which emulsion explosive can be withdrawn from the reservoir 12.

[0041] The installation 11 further includes a pump 16, located downstream of the reservoir 12.

[0042] An inlet of the pump 16 is connected to the outlet 14 of the reservoir by a first ancillary pipe section 18. Thus, by applying suction with the pump 16 along the pipe section 18, to emulsion explosive contained in the reservoir 12, the pump 16 can withdraw emulsion explosive from the reservoir 12 along the pipe section 18.

[0043] The installation 11 also includes a vertically extending pipe 20 that extends vertically down the mine shaft 13 to an underground location 22, to which underground location emulsion explosive would be delivered by the installation 11.

[0044] The underground location 22 is located at a depth of 500 m or more beneath the surface 13 of the body of earth of the mining operation, e.g. 680 m. Thus, the vertically extending pipe 20 has a length of over 500 m, approximating the depth of the underground location 22.

[0045] The installation 11 further includes, upstream of the vertically extending pipe 20 a second ancillary pipe section 24 that connects an outlet of the pump 16 to an inlet 26 to the vertically extending pipe 20.

[0046] The pipe section 24 has a so-called goose-neck configuration 28 immediately upstream of the inlet 26 to the vertically extending pipe 20.

[0047] A first valve 30 is located in the pipe section 24 between the pump 16 and the goose-neck configuration 28.

[0048] A second valve 32 is located in the goose-neck configuration 28.

[0049] The first valve 30 is configured to close-off the pump 16 from the goose-neck 28.

[0050] The valve 32 is configured selectively to allow and disallow atmospheric air into the goose-neck 28 from outside of the pipe section 24.

[0051] Connection of the outlet 14 of the reservoir 12 to the inlet 26 to the vertical pipe section is such that emulsion explosive can be withdrawn from the reservoir 12 and pumped, continuously and airtightly, into the vertically extending pipe 20, wherein airtight refers to the region between the outlet 14 of the reservoir 12 and a downstream end of a continuous volume of emulsion explosive extending from the outlet 14 into the vertically extending pipe 20.

[0052] The installation 11 also includes a secondary emulsion explosive reservoir 34 at the underground location.

[0053] The installation 11 further includes a third ancillary pipe section 36 that extends between a downstream end of the vertically extending pipe 20 and the secondary reservoir 34, such that emulsion explosive travelling along the vertically extending pipe 20 can be fed into the reservoir 34 along the pipe section 36.

[0054] Use of the installation 11 in performing the method of the invention will now be described with reference to FIGS. 2 to 7.

[0055] At start-up, as illustrated in FIG. 2, the reservoir 12 would contain a predetermined stored volume of emulsion explosive, a predetermined volume of which needs to be transported to the underground location 22.

[0056] With valve 30 open and valve 32 closed, the pump 16 is activated to apply suction to the emulsion explosive contained in the reservoir 12, thereby withdrawing emulsion explosive from the reservoir 12 and pumping withdrawn emulsion explosive into the vertically extending pipe 20 along the pipe sections 18 and 24.

[0057] Thus, a continuous volume of emulsion explosive, extending from the reservoir 12, through the outlet 14, the pipe section 18 and, the pipe section 24, and into the vertically extending pipe 20, is formed, air-tightly between the reservoir and a downstream end of the continuous volume of emulsion explosive.

[0058] As pumping continues (see FIG. 3), the volume of emulsion explosive pumped into the vertically extending pipe 20 extends progressively further along the vertically extending pipe 20. Initially, movement of the emulsion explosive in the vertically extending pipe 20 is driven by the pump, but once a sufficient volume of emulsion explosive has been pumped into the vertically extending pipe 20, movement is assisted by gravity.

[0059] In accordance with the invention, discontinuation of pumping is required. In this regard, two scenarios may exist. These are discussed with reference to FIGS. 4 to 7.

[0060] In one scenario, referring to FIGS. 4 and 5, pumping is discontinued only after discharge of emulsion explosive into the reservoir 34 has commenced.

[0061] As will be seen from FIG. 4, a continuous volume of emulsion explosive extends from the reservoir 12 into the reservoir 34, signifying that pumping continued beyond the commencement of discharge of emulsion explosive into the reservoir 34.

[0062] Once a predetermined volume of emulsion explosive has been withdrawn from the reservoir 12, and has passed beyond the valve 30, pumping is discontinued and the valve 30 is closed.

[0063] Discharge of emulsion explosive downstream of the valve 30 then continues under force of gravity, with a vacuum being created downstream of the valve 30, and upstream of an upstream end of the volume of emulsion explosive contained in the vertically extending pipe 20, as shown in FIG. 5.

[0064] To ensure complete discharge of emulsion explosive from the vertically extending pipe into the reservoir 34, it may be necessary to allow air into the vertically extending pipe 20, which would be achieved by opening the valve 32.

[0065] In another embodiment, as discussed with reference to FIGS. 6 and 7, pumping is discontinued before discharge of emulsion explosive into the reservoir 34 has commenced.

[0066] As shown in FIG. 6, a downstream end of a volume of emulsion explosive pumped into the vertically extending conduit is still spaced from the reservoir 34, at a time when a predetermined volume of emulsion explosive has been pumped passed the valve 30. At that time, pumping is discontinued, and the valve 30 is closed. Thus, a discreet “slug” of emulsion explosive is created downstream of the valve 30, again with a vacuum being formed as described above.

[0067] Continued movement of the slug down the vertically extending pipe 20 would be under force of gravity, ultimately resulting in the slug discharging into the reservoir 34, as shown in FIG. 7.

[0068] Again, as in the first-mentioned embodiment, it may be necessary to allow air into the vertically extending pipe by opening valve 32 for complete draining of emulsion explosive from the vertically extending pipe.

DISCUSSION

[0069] THE CONVENTIONAL APPROACH to vertical transport of emulsion explosive is to drop emulsion explosive freely, under gravity, along a pipe that is open to the atmosphere.

[0070] Beyond a certain depth, this approach is no longer feasible, however, due to the flow of emulsion explosive becoming turbulent as a result of shearing between the emulsion explosive and a pipe along which it is dropped.

[0071] In the present invention, the applicant has surprisingly found that by positively pumping explosive down a vertically extending pipe in an air-tight manner, and thereafter discontinuing pumping, after a predetermined volume has been pumped into the vertically extending pipe, such damage is significantly reduced and even avoided.

[0072] In this regard the applicant has found that pumping at a rate lower than the gravity flow rate for a particular predetermined volume of emulsion explosive is particularly advantageous, in that damage to the emulsion is virtually obviated.