The project, which would become the European Union's only open-cast uranium mine if given the go-ahead, has faced local opposition since it was proposed.
The proposed tax, to be applied on the nominal value of extracted metals, would affect copper miners that produce more than 12,000 tonnes of the metal and those extracting 50,000 tonnes of lithium a year.
A unit of the company, Black Mountain Metals LLP, will buy the Lanfranchi nickel project in the state of Western Australia for $15.1 million from Panoramic Resources.
Partners may lose their right to develop the Mt Holland lithium project after a recommendation by a unit of the West Australian government that regulates mining leases.
Around 1,500 staff at three alumina refineries and two bauxite mines walked out on Aug. 8 over a new workplace agreement they say does not offer sufficient job security.