The PFS was originally due for completion at the end of the first quarter for 2012.
Aspire said it missed this target to allow for the inclusion of quality data for resource and reserve modelling.
However, detailed engineering design and capital expenditure estimates were largely completed.
The PFS is proposing the development of a large open scale open pit operation at Ovoot with the mine tipped to produce 12 million tonnes per annum of run of mine coal.
The Ovoot project is situated 300km to the northwest of the Elegest coking coal province, which has more than 1 billion tonnes of coal reserves.
Possible products which could be yielded from Ovoot include an unwashed product that bypasses the wash plant, a premium low-ash product and a blended low-ash product.
Aspire said an announcement regarding a rail prefeasibility study was also imminent.
The study will analyse the viability of a northern railway which will transport coal from its Ovoot project through Moron to Erdenet.