They're oversupplying to China to lower the market price for...

They're oversupplying to China to lower the market price for Iron Ore and undercut smaller producers (i.e AGO).
Soon enough these smaller magnates will have to cut supply or sell at a loss and effectively ruin their business completely.

Im not 100% on the facts, but BHP produces at $35 per tonne, and AGO around $55 or so.

If you look at AGO's graph, that tells a tale. Its short term pain for long term gain in BHP.

If they wanted to pump up the iron ore price they would sell less. But they want it low to undercut the competition.
It may not happen for 3-5 years, but when it does. RIO and BHP will have more than a fair share of the Iron Ore market...
Which is worth trillions in itself as ASIA develops more and more.

Keep it safe and accumulate more at these prices.
Think it will go to around $25 now, but then come back.

Wouldn't be surprised to see it at triple figures come the turn of 2020