The prospectus for the initial public offering of Aston is expected to be lodged with the Australian Securities and Investments Commission next week, possibly Thursday.
The source said the bookbuild will begin early next week, with the private coal company canvassing the market to bring in institutional investors.
The float was not a retail play and only a small portion of the shares would be available to retail investors when floated, according to the source.
The source said it would be accurate to say Aston was on track to list in early August or in the next few weeks.
Noble and Itochu will take a combined stake of $100 million in the float while Xstrata and Peabody both failed to secure early stakes in Aston during recent talks.
“Aston has always been very keen to maintain its independence,” the source observed.
He said Aston management probably believed its Maules Creek coal project, located in the Gunnedah Basin of New South Wales, was worth “a lot more than it is now”
Commodities trader Noble was noted for working well with companies at the early stage of developing infrastructure.
Aston does not have any port access for exporting coal through Newcastle but the capital raising is expected to provide the necessary funds to make these arrangements.
Xstrata has a long track record in acquiring coal companies while Peabody even made a takeover play for Macarthur Coal a few months ago.
But these major coal miners will have to wait until the Aston float if they would like to gain any stakes.
Entrepreneur and former electrician Tinkler will gain a 40% stake in Aston once it is listed.
The float is set to be the biggest so far this year.
Located about 18 kilometres northeast of the town of Boggabri, the Maules Creek project is targeting 13 million tonnes per annum of raw coal for at least 21 years of open cut mining, with development scheduled to start in the December quarter of 2011.
The coal reserves total about 240Mt while total resources are estimated to be 610Mt of thermal and semi-soft coking coal.
Aston will mine the reserves using excavators and shovels along with a fleet of haul trucks, dozers and graders.
The operation workforce is estimated to be 400 permanent employees.
To get the coal out, Aston is seeking government approval for the construction of a rail spur, rail loop and associated load-out facility to link up with the Werris Creek to Mungindi railway line.
Aston purchased the Maules Creek project from Rio Tinto subsidiary Coal & Allied for $480 million cash in November.