Pike said it was using the raiseboring process to ream out the shaft to exhaust air and any gas from the mine face.

The raisebore equipment was flown in from Australia via a heavy lift helicopter.

In the shaft hole construction, a pilot hole has so far been drilled down to the coal seam from the surface and will later intersect the Pike River mine’s underground tunnel near the end of the 2.3km access tunnel.

Over the next week the company will excavate a chamber underground for the reaming head to be attached to the raisebore drill string.

From that stage the large raisebore motors on the surface will turn the reamers and pull it upwards through the ground, with fallen material to be removed from underground.

Pike expects the ventilation shaft to be completed by the end of the March quarter.

Meanwhile, Pike has contracted Australia’s Valley Longwall Mining Services to drill five in-seam boreholes over some 7km of the Brunner coal seam.

The single drill rig is drilling ahead towards the ventilation shaft location.

Pike said later holes would delineate the pit bottom underground.