News
Ventilation Shaft Raiseboring Complete
Pike River Coal has completed raiseboring the main 108-metre deep ventilation shaft from its underground mine to the surface a number of weeks ahead of schedule.
Raiseboring the 4.2-metre wide, $7million ventilation shaft, a critical factor in being able to press ahead with mining premium hard coking coal, commenced on 20 December 2008 and was completed today.
Work now starts on supporting the walls of the ventilation shaft with steel mesh and bolts, followed by the installation of the surface extraction fan (to exhaust air and any gas from the mine face) during February 2009. Further excavations in the pit-bottom area will also proceed to create space for the second continuous miner.
Pike River's chief executive Gordon Ward said "Completing the raisebore is a good milestone to complete at the start of the new year and will assist us in meeting our revised production forecast".
The ventilation shaft is a key part of the infrastructure to create a safe working environment for the miners and the heavy coal cutting machinery that Pike River will use to ramp up coal production.
Because of difficult rock conditions in a 35 metre zone immediately below the surface, ‘coring' the ventilation shaft had been expected to take longer, but the job turned out to be more straightforward. The pilot hole drilled in December 2008 provided evidence that the large quantities of cement injected into the top 35 metres to solidify the ground had been effective. That was proven correct when the raisebore successfully cut through that zone without difficulty. Little water was encountered and the ventilation shaft is in very good condition.
Since breakthrough to coal in mid-October 2008, Pike River has been limited in the amount of mining equipment that can be located underground due to insufficient ventilation.
From mid-January 2009 there will be enough ventilation for the combined operation of the road header and one continuous miner to cut coal; and for the inseam drilling unit which plots the best way forward in the coal seam by drilling ahead.
The second continuous miner will be put to work when the surface extraction fan is installed during February.