Operating Shearer with >2.5% CH4 in Tailgate 20th October 2017
Mr Marlborough attended Grosvenor Mine to download gas data from the monitoring system.
Again there was discussions about powering up the Shearer and AFC with the authorisation of the Underground Mine Manager with equal to or greater than 2.5% in the Tailgate roadway.
It is described as “not acceptable”.
Illegal is the correct term.
Why has this situation been allowed to continue for a month now with another 2 weeks given to review the procedure?
I explained that it was not acceptable to move the LW Shearer when the general body Methane concentration in the TG return is equal to or greater than 2.5%. I pointed out that the gas monitoring screen shots previously provided by the mine show that the shearer position in the Tailgate Shuffle zone does not generate excessive amounts of methane in the Tailgate. The risk of methane ignition was discussed and I showed sketch drawings of TG layout with the air sweeping around the shearer and the likely methane concentrations to be found around the end of the TG AFC drive area.
SHEARER POSITION IN TAILGATE DOES NOT GENERATE ADDITIONAL GAS FROM GOAF.
LEAVES ONLY FALLS IN GOAF, BAROMETRIC FALLS AND FACE EMISSIONS AS THE SOURCE OF ADDITIONAL METHANE THAT SENDS GENERAL BODY > 2.5% IN THE TAILGATE.
WERE THE FACE EMISSIONS PART OF THE DIAGRAM?
POWERING UP AND MOVING THE SHEARER IN >2.5% METHANE FOUND TO BE AN UNACCEPTABLE RISK BY DNRME.
ONE QUESTION IS, HAS THE MINE SHMS CONTINUED TO ALLOW THE POWERING UP AND MOVING THE SHEARER IN >2.5% METHANE?
THIS COULD ONLY BE DONE BY PUTTING INTERLOCK IN BYPASS.
WHAT STEPS HAS Mr MARLBROUGH (DNRME) AND Mr GARDE TAKEN TO ENSURE WHAT THE INSPECOR HAS FOUND TO BE AN UNACCEPTABLE RISK?
RISK ASSESSMENT TO REVIEW THE TARP DUE NEXT WEEK.
IT HAS BEEN 4 WEEKS SINCE THE SECTION 168 DIRECTIVE WAS ISSUED AND WILL BE 6 WEEKS BY THE DUE DATE OF THE DIRECTIVE?
Me Garde stated that the mine was holding a risk assessment to review the TARP the following week, with a view to revising the TARP to satisfy the terms of the Directive issued to the mine on 12 September 2017. Mr Garde stated that he was very aware that the next Longwall block may be different in gas characteristics as there will be an adjacent goaf alongside which the first Longwall did not have.
Mr Garde explained the actions being taken by the mine in development to try to predict and minimise the effects of floor heave that had been experienced in the past. The mine is to be congratulated for its pro-active approach to this issue.
HAS THE FLOOR HEAVE MECHANISM BEEN DETERMINED YET?
IS IT GEOTECHNICAL STRESS RELATED OR GAS PRESSURE RELATED?
HAS THE DECISION TO REMOVE THE LOWER PART OF THE SEAM IN THE LAST BLOCKS OF LW101 ALSO COINCIDED WITH THE END OF >2.5% METHANE GB IN THE TAILGATE?
MRE – Grosvenor Coal Mine Citec Upload+ comments- 20.10.2017
