Pike chief executive Gordon Ward said the Alimak raise, used to restore ventilation, was “painstaking work but the bypass was completed on time and within budget over the weekend and production can now push ahead”

The main 108m air shaft at the New Zealand south island mine, completed in January 2009, was subsequently blocked by a rock fall at its lower level before reinforcing bolt-and-mesh had reached down that far.

Pike River Coal plugged the rock fall in February 2009 with concrete poured down from the top of the shaft, commissioned the drilling of a 600mm slimline air vent to get some air down to the pit bottom, and brought in an Alimak team from Australia to work around the clock to cut a bypass shaft around the blockage.

The slimline hole was completed in mid-May, providing enough air for the roadheader to resume cutting coal. The main shaft bypass was holed though yesterday and the shaft top fan was able to start exhausting air up the shaft.

The roadheader has been joined by one of two continuous miners, with the second due to go into operation shortly.

With flow-through ventilation restored to the pit bottom, final works can be completed on the coal crusher and the water-fed flumes in the pit bottom and the slurry pipeline, which, from mid-June, will carry the coal 10 kilometres down to the Coal Preparation Plant for processing and stockpiling.

Ward said the company, with all key infrastructure in place, is on schedule to send its first export shipment of 60,000 tonnes to Japan in the July-September quarter.

The mine is expected to reach its full production rate in the October-December quarter when roadways in the coal seam have been opened up by the heavy cutting machines to provide access for high-pressure water cannons to start blasting coal out of the seam at the rate of up to 2000t a day.