This extract is from an article on the CSIRO website:...

This extract is from an article on the CSIRO website:

http://csiro.au/science/AlternativeOres.html#4

"High phosphorus ores

Another serious problem is the phosphorus content of Australian iron ores.

'There are huge deposits of high-phosphorus Brockman ore in Western Australia that are close to existing infrastructure; however the high phosphorus levels make them more difficult to sell except in boom times,' says Dr Holmes.

Physical separation processes can remove some of the phosphorus, but substantial iron is lost in the process.

Alternative approaches, such as heat treatment and leaching, are currently considered uneconomic, with the best option being to remove the phosphorus at the hot metal stage.

This pushes the cost of removal onto the customer, although iron ore prices can be adjusted to take account of the additional process step."

I suspect the ore they are selling to Rio Tinto will be blended with low phosphorus ore to make it marketable. Unless there is a shortage of low "P" ore, why would you bother?