* K+S buys mining licenses for Ashburton salt project
* Eyes production facility with output of 3.5 mln tonnes/yr
* Capex could come to A$350 mln
* Final decision to be made in 2019 at earliest (Adds further details of project, production method, background)
FRANKFURT, May 25 (Reuters) - German potash and salt group K+S SDFGn.DE has bought mining licenses for the Ashburton salt project in Australia from local investors to tap demand from the chemicals sector in Asia, especially China.
K+S, the world's biggest salt maker, said on Wednesday it plans to set up a production facility near Onslow in Western Australia that could put out around 3.5 million tonnes of salt a year, boosting the group's output by more than 10 percent.
Capital expenditure for the project could come to A$350 million ($252 million), but K+S said it would not make a final decision on whether to build the facility until it had received the necessary permits, which would take at least three years.
K+S, which last year fended off a takeover approach by larger Canadian rival Potash Corp POT.TO , aims to grow the salt business in new regions including Asia, where it so far does not make any salt, to bolster earnings.
The proposed Australian facility would make solar salt, which is produced by evaporating ocean water in the sun.
There has been speculation that K+S could sell or float the salt business, which generates around half of group sales and a third of operating profit, to focus on potash mining. But Chief Executive Norbert Steiner last month said salt was a strategic business. = 1.3881 Australian dollars)