One of the major concerns of companies in the coal game is adequate ventilation, which is a vital component of a safe underground working environment, as it serves to remove gases, fumes and dust from the working faces.
Therefore, the need for a ventilation stopping that can be erected rapidly to keep up with heading advances and improved mining machines are an important factor in efficient longwall development.
Longwall Associates New South Wales manager Mike Coffey said the company had begun manufacturing and supplying a new, lightweight ‘Fleity’ flexible stopping as a result of this need and from subsequent trials carried out at Tahmoor colliery in 2005.
The first Fleity stopping was developed and patented in 1986 by Phil Smith, but since then it has been adapted to suit modern underground mines and is now manufactured and supplied by Longwall Associates under an agreement with Smith’s company, Fleity.
“The stoppings direct the air flow to the working sections to remove the dust and any gases or fumes encountered from the working faces into the return airways and then out of the mine via the main ventilation fan,” Coffey said.
Coffey said when Tahmoor Colliery operators were seeking a quick and easy method to erect stopping during development, the Fleity stopping material (made of a flexible sheeting composite) was incorporated into a simple, lightweight, easily deployed stopping.
“The Fleity material strength and flexibility and its reduction of leakage compared to brick and plaster type stoppings make it a viable solution to ventilation problems, particularly floor heave as experienced at Tahmoor Colliery,” Coffey said.
The stopping is installed off the continuous miner using the miner bolting rigs during the panel development and a flexible access door may also be supplied with the stopping if required.
The Fleity stopping has also been installed at the Appin Colliery during development of the new longwall, due to start up in October.
Appin mine Development Co-ordinator Glenn Birchall said the stopping was chosen because of the speed of installation and the fact it can be reused in development and in the longwall – saving material, time and money.
The Fleity stopping material meets the NSW Mines department requirements for both fire resistance and anti-static and can be designed and manufactured to meet the requirements of the Queensland Coal Mining Safety and Health Regulations 2001 Schedule 4, which calls for stopping ranging from 14kPa to 140kPa.
The stopping is supplied as a compact unit with the floor beam and rib straps attached to the main body of the stopping for ease of transport and later removed to allow the initial installation.
Phil Smith said Fleity stopping can also be used as a permanent seal, as the material used has been tested to a hydrostatic pressure in excess of 250kPa and carries test report N05/9117 for use in underground coal mines.
The lightweight Fleity stopping is designed to be installed during the development drivage - making it easily deployed and installed during the panel services advance.
When the panel development is completed and the ventilation is changed over, ready for longwall production, the stoppings are easily rolled up to allow access to the maingate.
Once the longwall face passes the cut-through the stoppings can be deployed again allowing the goaf to be quickly sealed off with a rated stopping.
Longwall Associates said air permability tests show that the lightweight Fleity materials are highly resistant to air flow.
The company said some mining engineers are considering using Fleity stoppings to solve the problem of leakage through cementatious seals, particularly where access is difficult. The lightweight Fleity stopping can be easily carried and then installed over a leaking seal quickly and effectively.
