RIO Tinto subsidiary Energy Resources of Australia plans to boost annual uranium production by more than a third by heap-leaching low-grade ore at the country's biggest uranium mine.

ERA submitted referral documents yesterday to the federal Environment Department for a project that would leach 1875 to 2000 tonnes of uranium from stockpiles and unmined ore at the Ranger uranium mine in Kakadu from 2012.

A spokeswoman for ERA said the production would be in addition to the mine's current rate, which is about 5200 tonnes a year.

According to ERA, the ranger mine currently provides 11 per cent of the world's uranium needs.

The heap-leach process, which involves treating five-metre high piles of mined ore with sulphuric acid, is also planned for Rio's Rossing uranium mine in Namibia.

ERA said it hoped to produce 10 million tonnes of ore a year to leach out 15,000 to 20,000 tonnes of uranium between 2012 and 2020.

The miner plans to finish the heap-leach pre-feasibility study this half.

ERA shares rose 52c to $20 yesterday.