Earlier this year there was an article in one of the papers...

Earlier this year there was an article in one of the papers where FMG were quite openly promoting transporting ore for other producers, because they see it makes good economic sense for them ie. get maximum use of the rail line and get some income from third parties. Anyway, in the article FMG said they had been in discussions with IOH and Yilgarn Mining (these were the only 2 companies mentioned) about access to the railway line.

BHP also claim that the issue about access to their railway line is attributable to different grade ores to theirs and how it complicates the storage etc etc. Their complain about FMG's access request is because FMG want to transport Mindy Mindy ore that is in the low 50's in Fe content, whereas BHP doesn't process anything less than 56% - hence the complications. However, BHP did say they were happy to buy ore at the mine gate from other producers. There's an article about this at the attached link. http://www.smh.com.au/news/business/why-bhp-doesnt-want-to-share-its-railway/2006/07/23/1153593210315.html