Oct 29 (Reuters) - Billionaire Gina Rinehart's Hancock Prospecting has raised its stake in Australia's Arafura Rare Earths ARU.AX to nearly 15.7%, the latter said on Wednesday while announcing an around A$475 million ($308.65 million) placement via two tranches.
($1 = 1.5389 Australian dollars)
(Reporting by Sneha Kumar in Bengaluru; Editing by Alan Barona)
((Sneha.Kumar@thomsonreuters.com))