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Moranbah North Tailgate 2x Methane HPI’s MRE 17th January 2018

Moranbah North Tailgate 2x Methane HPI’s MRE 17th January 2018

MRE – Moranbah North 17.01.2018 (003).pdf

Mr Craig Manz, SSE, Mr Stanton, Mr Casper Badenhorst, SHE Manager, Mr Paul Stephan, Production Manager, Mr Wes Noble, Acting Technical Services Manager, Mr Peter Finnen, Acting Engineering Manager and Mrs Larnie Mackay, Personal Assistant to General Manager.

DNRME Inspector Les Marlborough

We discussed an incident at a Longwall mine which had experienced 2 incidents of Methane exceeding 2.5% in the Longwail TG return that had not been reported. An investigation was underway at the mine as it appears that the TARP requirements were not followed on shift and the actions required to be taken were not followed. I stressed the importance of ensuring people with actions required under a TARP understand their responsibilities under the TARP.

We had a discussion concerning the 2 Methane exceedances that the mine had reported on 13 and 14 January. The mine’s investigations have indicated that the cause of the exceedances is due to the overlying strata. The sandstone that lies just above the coal seam (approx. 10m above the seam) has thickened jn the area where the Longwall is currently located. This has increased from approximately 4 m in thickness to over 10 m thick. It is believed that this sandstone is “bridging” and the goaf caving is not intersecting the goaf drainage holes, which are normally drilled to the top of the sandstone band.

This is evidenced from the current face conditions which show heavy face slabbing, indicating there is a cantilever effect from the sandstone which is resulting in excessive load on the coal. In addition, the gas purity of the goaf drainage holes, normally around 60-70% Methane is current*y, at the 3 holes immediately behind the LW is 80-95% Methane, which suggests the holes are not drawing from the goaf but from the overlying P seam. The hole spacing at the present time is 100m. The mine is in the process of drilling infill holes at 50m spacing in the area of the thick sandstone. These holes will be drilled through the sandstone to ensure the gas capture from the goaf area is achieved. The lesson learnt from this will be used in future goaf drainage hole design and spacing when planning the goaf drainage for Longwall operations.

I requested a copy of the completed investigation report for the Methane exceedances when it was completed.

 

The face was in production and on arrival at the MG the MG operator explained to me the shearer was just leaving the TG end cutting towards the Maingate. The operator showed me the Citect screens on the MG control unit. The outbye TG gas monitors were showing 1.36% methane. Shearer and TG AFC were both reading 0.5% Methane.

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