Methane Inrushes in Development till October 2017 Grosvenor Mine
26th OCTOBER 2017 Gouldstone
METHANE INRUSHES
MG 103 Development
The Development has progressed beyond 29CT where the sequence was amended to include a short drill stub in the 29CT to allow coring and two flanking holes for B and C headings.
This was as a result of recent floor-blow incidents dated as follows –
30/08/17 – estimated that 240 cubic metres of methane (above normal background) was liberated – 1200mm floor coal left in floor.
4/10/17 – estimated that 60 cubic metres of methane was liberated 600mm floor coal left in floor.
26/10/17 – last night there was another minor event where again floor coal had been left just inbye 29CT in C heading, details are still to be assimilated.
The site of the previous night’s minor floor-blow incident was viewed and it was apparent that the floor grade and road height through the intersection C29 was variable, with a swilley before the intersection and a hump inbye the intersection at the site of the incident.
29/08/17 Ventilation peak of 4.64% Methane through Auxiliary Fan
This was as a result of a floor blow incident and is covered later in this MRE.
JUST UNDER THE LOWER EXPLOSIVE LIMIT
FLOOR HEAVE/METHANE INRUSH EVENTS STILL OCCURRING IN DEVELOPMENT.
WHAT WAS THE METHANE CONCENTRATION PUT THROUGH THE AUXILLIARY FAN and TOTAL QUANTITIES OF METHANE LIBERATED?
ADDITIONAL HOLES DRILLED FOR COMPLIANCE CORES AND FLANKING HOLES
In future methane drainage holes will be drilled to periodically touch floor as at the moment most are in the upper half of the seam and it appears that the Tonstein band is acting as a cap rock.
HOW HARD IS THE TONSTEIN BAND?
IS IT CONVENIENT TO USE THE TONSTEIN BAND AS A FLOOR HORIZON IN DEVELOPMENT?
The Mine has instigated a Floor Heave and Gas Release Management team who are continuously monitoring progress and all parameters to identify potential causes and solutions. I have read through the sets of minutes provided to familiarise myself with the action being taken.
The matter is receiving constant attention with monitoring of the environment under continuous scrutiny,
WHO IS ON THE “FLOOR HEAVE and GAS RELEASE MANAGEMENT TEAM?
ARE ANY ERZC’S, SSHR’S (SITE SAFETY AND HEALTH REPRESENTATIVES)?
