Yorke Peninsula resources explorer Rex Minerals has upgraded its estimated ore reserves by 50 per cent.

The company said its sixth mineral resource upgrade in three years had reconfirmed its Hillside copper project on the Yorke Peninsula, South Australia, as Australia’s largest open pit copper project.

“The first 12 years of production are now covered as Ore Reserves providing further confidence in the detailed mine plan and further support for the completion of project finance negotiations,” it said in a statement to the stock exchange today.

Rex’s managing director  Mark Parry said the company continued to look for joint venture partners to move the project ahead.

“Rex started resource drilling at Hillside in 2010 and in just 3 years, has delivered one of the best long-life open pit copper discoveries in Australia since Ernest Henry,” he said.

“A resource of this scale and a reserve of this quality so close to existing infrastructure provides significant financial flexibility as we look to finalise project funding in the months ahead.

“We are continuing discussions with copper concentrate, iron ore buyers and potential joint venture partners which can provide significant financial support to Hillside.

“With relatively low capital intensity, low operating costs, and the simplicity of open pit mining in a first world location, we are confident Hillside has all the right attributes for successful financing and development.”

Rex’s share price has struggled in recent months and closed yesterday at 32 cents, half its value of six months ago and well short of its $2.75 high.

Ernest Henry is a copper and gold mine near Cloncurry in north west Queensland and forms part of the massive Xstrata north Queensland operations, which includes the Xstrata Mount Isa Mine.