Gina Rinehart has won the battle of the billionaires for Atlas Iron

Mining magnate Gina Rinehart has won control of junior miner Atlas Iron in a battle of the billionaires.

Her company, Hancock Prospecting, announced today its voting power in Atlas passed 90% and that it will compulsory acquire the rest.

"We will now be turning our attention to how best to integrate the Atlas business," says Hancock CEO Garry Korte.

Rinehart won the company in a three-way contest with Chris Ellison's Mineral Resources and Andrew Forrest's Fortescue Metals.

All three saw upside in consolidating the Atlas assets, which have high iron content ore, in the Pilbara into their own.

Rinehart trumped Forrest with an offer of 4.6 cents per Atlas share, valuing the iron ore miner at $427 million.

Atlas Iron was an early victim of falling iron ore prices. In April 2015, it announced it was mothballing its mines because it was costing more to dig up ore than buyers were willing to pay.

The crash in iron ore prices was then driven by softening Chinese demand. Since then the company has restructured, global prices have surged and the miner is cash flow positive.