ICGCM Papers:
Operator Case Histories
 
 
Longwall Shield Recovery, Using Phenolic Foam Injection for Gob Control As An Alternative to Recovery Mesh
32nd International Conference on Ground Control in Mining
Longwall Shield Recovery, Using Phenolic Foam Injection for Gob Control As An Alternative to Recovery Mesh
by
James D Pile, BHP Billiton, Waterflow, United States
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[Conference] 32nd International Conference on Ground Control in Mining
[Price] Free  [Comments] 0
[Topical Area] Operator Case Histories
[Author] James D Pile, BHP Billiton, Waterflow, United States
[Abstract] 
Key Conclusions:
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Success can be achieved in the face of technical adversity. In spite of the fact that this method of gob stabilisation had not been knowingly successfully demonstrated in the United States to date, adherence to the procedure and hardware successfully used in other coal mining regions of the world, delivered a product and technique that not only worked, but did so better than expected. I do not suppose that it is very often that you can get to see a negative angle of repose on the longwall gob.
Key Findings:
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As it was a technique that has been used to great effect in Germany, to a lesser extent in Australia, but not knowingly to date in the United States, phenolic foam was chosen, and injected from between the shields into the gob behind them. To ensure that nothing was left to chance, and thereby guarantee the success of the project, the procedure used in Germany was used, down to the use of the same hardware, which was sourced from its North American supplier.
Objective of the Paper:
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The objective of the paper is to show how stabilisation of the gob was achieved during shield recovery, thereby minimising flushing, and improving operator safety.
Problem Statement:
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Following a methane ignition in the active panel of a longwall coal mine, the affected panel was successfully isolated from the rest of the mine. This allowed for the remainder of the mine to return to regular operation, and the conventional practice of having to seal the portals for a defined period of time was avoided. After the affected panel had remained isolated for the statutorily required ‘cooling off period’, it was reopened in preparation for longwall face recovery. As it was not possible to move the shields from their existing positions to facilitate the installation of recovery mesh prior to shield recovery, alternatives methods had to be considered to stabilise the gob and minimise flushing, thereby improving operator safety.