SHARES in Energy Resources of Australia slumped almost 6 per cent as the uranium miner posted a first-half loss after heavy rains forced a suspension of operations at its Ranger Mine.

Darwin-based ERA posted a net loss of $121.75 million for the six months to June 30, compared with a profit of $22.68m a year earlier, the miner's statement said today.

Revenue increased 12 per cent to $235.56m.

ERA said its operating and financial results for the half-year to June 2011 were "significantly" affected by the suspension of processing operations at Ranger, announced last January 28.

"The suspension was taken in response to the significantly above-average 2010/11 wet season encountered in the Northern Territory," ERA company said.

With the restart of operations on June 15, ERA said it now estimated 2011 production of uranium oxide at 2600 tonnes.

ERA stock slumped 23 cents, or 5.3 per cent, to $4.11 today.

Additional pond-water treatment capacity has been commissioned to help provide earlier and longer access to the bottom of the pit at Ranger.

The uranium market in the short term "appears to be well supplied" due to adequate inventory coverage held by utilities, along with increased production, especially from Kazakhstan, ERA said.

Volatility in the spot price of uranium oxide was likely to continue until the nuclear energy situation in Japan became clearer and the outcomes of the safety reviews of nuclear power facilities in China were released.

ERA said strong growth in China was expected to drive demand in the long-term.

"This is expected to significantly exceed any market contraction as a result of the Japan crisis," the company said.

"ERA continues to envisage a strong future for uranium, including continued price and demand growth with long-term demand exceeding planned supply."

The miner said it would spend about $120m exploring an untapped deposit that could extend the life of its Ranger mine.

One of the world's biggest uranium mines, Ranger is close to running out of ore. ERA said construction of an exploration decline at the untapped Ranger 3 Deeps resource is expected to commence in May next year, subject to regulatory approvals. ERA also said it has decided not to proceed with construction of a heap leach facility, which would have used acid filtration to process low-grade ore. While technically viable, ERA said the facility's high capital cost and present economic assumptions limit its value.

Earnings per share were negative 63.8c, compared with positive 11.9c a year earlier.

ERA directors decided not to declare an interim dividend for the financial year 2011, after an interim dividend of 8c per share the year before. No final dividend was paid for 2010.