The two big miners, BHP Billiton (NYSE:BHP) and Rio Tinto (NYSE:RTP), are all signed up for their Australian iron ore joint venture, and they're ready to go. Or are they?

Sure, the documents have been executed between the companies for the partnership that was agreed to in June, and regulatory submissions have been made. But submitting documents is one thing. Receiving approval is quite another. And beyond that, the combination could face stiff opposition from its steelmaker customers and even from other governments -- such as China's.

The companies rank with Brazil's Vale (NYSE:VALE) as the major threesome in the world of iron ore, a key ingredient in the making of steel. They plan to combine their iron ore operations in the Pilbara region of northwest Australia. Under the plan, which BHP CEO Marius Kloppers says has been talked about for years, BHP will pay Rio $5.8 billion in order to increase its share of the deal to 50% from 45%.

But the companies must still receive a blessing from both the Australian Competition and Consumer Commission and the European Commission. And then there are those who believe that, since the Chinese are huge iron ore customers, Beijing may try to work its way into the process for a say-so as well.

At the same time, even if the deal is approved, Australia is facing a labor shortage, with the unions restless and threatening to increase costs. The labor movement has already affected the energy industry, when a key Chevron (NYSE:CVX) and Apache (NYSE:APA) contractor was subjected to a strike in November. Beyond that, all this occurs just as Chevron and its partners, ExxonMobil (NYSE:XOM) and Shell (NYSE:RDS-A), are starting to construct their huge Gorgon liquefied natural gas project off Australia's west coast.

In the meantime, however, BHP in particular is keeping busy. It has just unloaded its unsuccessful Ravensthorpe nickel mine to Canada's Firs Quantum Minerals Ltd. for $340 million. Also, Friday and Saturday may find it returning to Iraq for the latest round of oilfield bids. With its significant oil and gas operation, BHP will be the one member of the big iron ore trio participating in the bidding process.

On Tuesday my Foolish Colleague Rich Duprey noted BHP among "5 Stocks Approaching Greatness." The group consisted of Motley Fool CAPS four-star companies that Rich felt were headed for higher ground. I especially agree regarding BHP and strongly suggest that Fools everywhere follow this solid company closely.

Fool contributor David Lee Smith has no financial interest in any of the companies named above. He does welcome your comments. The Fool's disclosure policy is made mostly of iron ore.