Coal Mine Services - Underground Construction, NSW Australia

CMS - Underground Construction

Projects

Centennial Coal - Mandalong Coal Clearance System.

The system was designed to handle the coal from the New Mandalong Longwall and 3 continuous miner units. Coal is conveyed from the seam via 350m of stone drivage to the top of the 2000t capacity surge bin some 35m above. The coal is then metered via a conical hopper system into 2 x 2000t/hour vibro feeders that controls the coal flow to both Delta and Eraring Power Stations. Eraring utilizes the old Cooranbong workings to deliver the coal into the screening plant on the Cooranbong surface some 12km away, before being sent to the power station via the overland conveyors.

Delta coal goes via the newly commissioned 4.5km underground conveyor system to be screened and delivered onto the overland conveyor system at the Train unloader station on Rutleys Road. The project was divided into several major mining contracts. Surge bin access roads, surge bin shaft construction, manufacture and installation of the surge bin metering hoppers and feeders and the extension of the Delta production unit workings to intercept the surface drift. Our staff has been involved with all the contracts with the exception of the surface drift.

Surge Bin Access Roadways

This was a 6.5m x 2.8m roadway, driven in stone at a gradient of 1 in 6. The companies Mitsui S200 handled the mining work in the single entry drivage to the top of the surge bin and then constructed the shaft top chamber. In addition to this preliminary drivage we also constructed the first overcasts for No 1 longwall return and the Main Gate belt drive.

The underground access roads to the Mandalong surface drift along with 260m of the 1 in 8 drift, to assist in the timing of the project and finally 1000m of brushing to allow the Longwall supports to be transported to the face line.

Surge Bin Shaft Construction

The shaft was 10.5m finished diameter and 35m deep. An initial 2.7m shaft was raised through the bunker section from the surface and the shaft widened by drill and blast. A 1m diameter raise bore was lined through to the surface to allow the top of the surge bin to be ventilated. Service pipes were installed and compressed air and shot crete were supplied direct from the surface.

A purpose designed winding system was utilized for the construction allowing man and material access for the drilling, blasting, support and shotcreting to be carried out in safety.

Surge Bin Steelwork Manufacture and Installation

The steel work was designed by SKM, H&M engineering manufactured the steel work and Ludowici supplied the feeders. The complex steelwork was installed utilizing the construction winding system, there was very little tolerance in the design. Sections of the steel hopper had to be placed exactly in position will only millimeters to spare. The final survey showed a vertical error of 3mm.

Delta Drivage

Initially it was thought the drivages could be taken entirely in the seam and 4 headings were driven to take advantage of the production after 2000m faulting caused a rethink, at this stage it was decided to carryout the work by contract and allow the mines production miners to carry on with the longwall and mains development program.

The first fault zone was a 6m down throw fault carried out with the Mitsui S200. The second zone was a 12m up throw which placed Great Northern conglomerate into the working, despite the conglomerate being at the absolute limit of the Mitsui S200, the 250m of stone work was completed. A total of 1600m of drivage was under taken, 400m of which was in some very poor geological conditions, and 950m were carried out under single entry conditions. The coal work was done with a Dash 3 miner.