Published in March 2005 Australian Longwall Magazine

The Tahmoor mine in New South Wales extracts steaming and medium-hard coking coal from the 2m Bulli seam. SES Mining won the contract from DBT and after eight months of design negotiation and manufacturing the pump station was installed successfully at the mine in May 2004.

The pump station is about 800m outbye of the longwall face and in the travelling road under the methane pipe. One limiting factor at Tahmoor was the seam section that required the pump station in operating conditions be no larger than 1.5m high and 1.3m wide. This presented a number of design problems that SES worked through with cooperation from Tahmoor and DBT engineers.

The installation involved four sleds – one sled with the shearer water tank, two sleds with three Hauhinco EHP emulsion pumps and a Hauhinco EHP shearer water pump, and one sled with a distribution control box and high set pump, outlet manifold and decompression system.

While this installation may sound similar to the systems used on most of the original longwall installations, according to the manager of SES Mining Michael Johnson, Tahmoor’s design had a few unique features.

The four sleds are located in the travel road and have four retractable steel wheels, hydraulically operated when the sleds are repositioned. They are also fitted with side shift cylinders to allow the pump station to be put hard up against the rib and underneath the methane drainage pipe.

“The main difference from the old pantechnicon system is we do not require staker chocks that move with every shear of the longwall. This system allows for the longwall face to advance up to approximately 270m before the pump station has to be relocated,” Johnson said.

Another reason Tahmoor opted to locate the pump in the travelling road rather than the maingate was the new high capacity conveyor. Also, the pump station would not have left enough room for access or safe movement to the face.

SES used Flintstone design wheels because the sleds would be stationary for several weeks. Conventional wheels, in typical moist mine conditions, would seize. The steel wheels use bronze bushes and plenty of lubrication.

“The biggest advance we have incorporated in this pump station is the decompression system which provides greater safety to the operators when the dump valve operates by reducing the high pressure spikes,” Johnson said.

“This is achieved by two Hauhinco DN32 decompression valves that electrically initiate and relieve the pressure spike and direct it back to the tank. They stay in operation until the pressure has stabilised down to 100bar, and then close.

“This provides a safety factor on the monorail hoses by reducing the shock loads and addressing the expansion of the hydraulic hoses and also the compressibility of the emulsion fluid.”

All the Hauhinco pumps used on the Tahmoor project are identical to those used on SES’ other pump stations. SES have 44 Hauhinco, EHP 3K 200/53 emulsion pumps and 21 Hauhinco, EHP 3K150/80 shearer water pumps operating in mines throughout NSW and Queensland.

“This is the first time this design has been used in an Australian longwall mine and possibly the first in the world. Should Australia decide to work in seams two metres or lower, this is a good design to adopt,” Johnson said.