Borehole intersections

Control the gas. Keep mining.

The Proflow Gas Bypass System seals an intersected drainage hole at the face as soon as it can be safely accessed. The airbag inflates in under 10 seconds and seals the hole, so the gas runs through the standpipe instead of into the roadway and mining can carry on. The hole is then treated within the time or distance specified by your site's borehole intersection process.

  • Sealed in secondsThe airbag seals against the wall of the hole as it inflates, in under 10 seconds once the standpipe is in position.
  • Treat the hole laterMining carries on once the hole is sealed. The crew treats it within the time or distance specified by the site's borehole intersection process.
  • Gets into tight spotsThe flexible hose reaches holes in tight spots off the miner.
  • Effective treatmentWith no pressure differential working against it, the sealant can cure and bond to the strata without gas or air paths forming.

The problem

It's the small leaks that stop a panel.

An intersected hole may still be active. Gas pressure pushes out of it, or the vacuum draws air into it.

If the hole is treated while that pressure differential remains, gas or air can form leakage paths between the sealant and the hole wall as the sealant cures. The problem is worse in wet holes. Those paths can remain after the sealant sets, leaving the hole leaking gas or drawing air.

Gas entering the roadway raises background levels at the face and can slow or stop mining. Air drawn into the range can trigger O2 and CO TARPs, requiring holes to be shut off. Crews then return to re-treat holes or replace leaking standpipes.

Across a panel, these delays add up. Where there is little float in the schedule, a panel may be cut short so the face roads can be driven, leaving coal inbye sterilised.

How it works

Seal the hole first. Treat it once it's sealed.

The airbag seals between the standpipe and the borehole wall, directing gas or air through the standpipe rather than around it. This allows the sealant between the standpipe and the strata to cure without the pressure differential working against it.

  1. 01

    Clear the hole

    Once the hole is under supported ground, scrape it out with the grout tamp.

  2. 02

    Insert and inflate

    Insert the standpipe into the hole and inflate the airbag to 60 psi with the regulated inflator.

  3. 03

    Hose over

    Repeat steps 1 and 2 on the hole in the other rib, then join the two standpipes with the hose-over.

  4. 04

    Treat the hole

    Treat the hole using the sealant and method specified by your site's borehole intersection process.

Installation overview only. The full installation procedure will be issued with the system.

Designed for development

Built around the way development runs.

The system came out of development operations. The installation sequence is designed to keep production delays to a minimum.

  • Combine grouting tasks

    Where the site's process allows, crews can pump grout around the standpipes while cable bolts are being grouted. The hole must still be treated within the time or distance specified by the site's borehole intersection process.

  • Use your site-approved sealant

    The airbag inflates through an air line inside the standpipe, so there is nothing in the annulus to work around. The choice of sealant stays with the site: hand grout, pumped grout or Silent Seal.

  • No separate gas bag

    A separate gas bag temporarily stops the flow, but must later be popped so the standpipe can be installed, releasing the gas behind it. With this system, the standpipe goes in at the face and its fitted airbag seals the hole in the same step.

Availability

In testing. Not on sale yet.

Both hoses have passed fire resistance and antistatic testing to AS 2660 at BPI Technologies. The airbag is still being tested. The system won't be sold until the airbag passes.

Contact us for test results as they come in, or to talk through how the system could fit your site's borehole intersection process.