* Nathan Tinkler sells horse-racing business to Middle East investors
* Former coal tycoon attempts return to industry
* Sports businesses still in trouble
By Jane Wardell
SYDNEY, May 21 Nathan Tinkler, a former pit electrician who became Australia's youngest billionaire by riding the country's mining boom before losing it all, is narrowing his focus as he attempts a comeback.
Tinkler said on Wednesday he had found a buyer for his beloved thoroughbred racing and stud empire, one of many sidelines on which he splurged millions of dollars after making his fortune.
The deal comes just a week after Tinkler announced his return to mining, with the purchase of a closed thermal coal mine from Peabody Energy for next to nothing.
The sale of Patinack Farm for an undisclosed sum to a mystery consortium led by UAE-based investment firm Cibola Capital would help fund his renewed coal ambitions, Tinkler said.
"My focus is on our core operations in resources and mining," he said in a statement. "The sale will allow further capital to be used in the development of our existing operations."
Almost a decade has passed since Tinkler, now 38, made his first investment in coal, buying the undeveloped Middlemount prospect in 2006. Within two years he made a profit of more than A$625 million on the deal and went on to buy another project, Maules Creek.
Riding a China-driven coal boom, his fortunes peaked in 2012, with the $5-billion merger of his Aston Resources and Boardwalk Resources with Whitehaven Coal Ltd.
Tinkler rocketed up the rich list and his name was routinely mentioned in the same breath as iron ore heiress and Asia's richest woman, Gina Rinehart, and Fortescue Metal Group Ltd's Andrew Forrest.
Celebrating his success, Tinkler acquired the trappings of a rich young man, including multimillion dollar properties, sports cars, a private jet and a helicopter.
The keen race goer also fulfilled a lifelong dream with the purchase of Patinack Farm and bought both the major sports teams in his adopted working-class coal-mining town of Newcastle.
But it all started to unravel in the second half of 2012 as coal prices started to slide. A year ago, Tinkler was forced to give up his stake in Whitehaven, his biggest source of wealth, to pay off creditors, and sell his Aston Metals business.
As the fallout continues, the National Rugby League association is brokering a change of control of Tinkler's Newcastle Knights after he defaulted on a A$10.5-million bank guarantee in March.
Local reports say he is also readying to sell the Newcastle Jets soccer team after belatedly paying off millions in unpaid taxes to end legal action brought the Australian Tax Office.
Other assets, such as the private jet and helicopter, are long gone.
Tinkler has also been a star witness at a state hearing into political corruption, flying in to Sydney from his Singapore base to give evidence about whether donations he made to a political party were designed to garner approval for his plans for a billion-dollar coal terminal in Newcastle.
Some analysts have doubts about the price tag of his new purchase - $70 million in cash, plus the assumption of $60 million in various obligations and liabilities.
The ageing thermal coal mine is a very different prospect from the undeveloped Middlemount and Maules Creek projects on which he made his billions and analysts say he is likely to have borrowed heavily to fund the purchase.
"It's ultimately a different strategy," said Andrew Harrington, who runs coal consultancy Indexys. "A lot depends on your view of the coal price." (Editing by Clarence Fernandez)