Alumina (ASX:AWC), a 40 per cent partner in the Alcoa-managed AWAC global alumina joint venture, said the industry's drive for alumina to be traded on global markets on a spot price/index-related basis instead of linking it to aluminium metal prices will produce large benefits.

Spot pricing for alumina is currently $US40 to $US50 a tonne higher than long-term alumina contracts. If this were to apply to all AWAC's expected annual output of 15.6 million tonnes of alumina, the additional revenue would be $US780 million ($A850 million).

The spot price for alumina had been higher than the contract price in the past five years, except briefly during the financial crisis, according to Alumina chief executive John Bevan.

Mr Bevan said it was not essential by how much the spot-related index price was higher than the contract price for alumina.

According to him, what matters is that the historic link with the aluminium price is cut, allowing alumina to be valued on its own fundamentals.

The Melbourne-based company expects the shift to full index pricing will take up to five years, with existing long-term contracts being washed out at a rate of 20 per cent a year. A similar shift is cooking in iron ore markets.

Mr Bevan's comments came on the release of Alumina's June-half profit report, which revealed an improvement from a loss of $US10 million in the prior corresponding period to $US22 million on an underlying basis.