BHP Billiton's head of its Olympic Dam expansion team is set to leave the company.

The mining giant said the departure of Graeme Hunt did not signal a change in its plans for the massive expansion of its Olympic Dam mine in South Australia.

The miner has also revealed it is restructuring its uranium and Olympic Dam division, which will now be folded into the nonferrous metals group headed up by Andrew Mackenzie.

BHP has scaled back the numbers of staff working on Olympic Dam, touted as a key growth project for the company, while it works through an environmental approvals process that is expected to take up to 18 months.

A spokesman for the company said Mr Hunt’s departure in late March and the reduction in staff numbers were related to the timing of the approval process and not a signal of a change in BHP’s commitment to the Olympic Dam project.

“This doesn’t signal any change in our focus on uranium as a key commodity in our future portfolio and is a reflection of the timing associated with the approvals process and the prevailing economic conditions,” he said.

“Graeme leaves the uranium business well positioned for the future with the expansion (and) growth configuration determined.”

Mr Hunt, a former president of aluminium and iron ore who has been with BHP for 35 years, was appointed head of a newly created uranium and Olympic Dam division in a 2007 restructure.

The creation of the division was at the time seen as a signal of the importance of the massive expansion project to the company’s future.

So the decision to fold the division into nonferrous metals is being seen by some as a sign that the expansion of Olympic Dam may be delayed as BHP slows spending on growth projects in response to the global slowdown.

Olympic Dam is a huge and complex polymetallic ore body and analysts said Hunt has played an important role in drawing up BHP’s five stage plan for its expansion into one of the world’s biggest open pit mines with annual output of 730,000 tonnes of copper and 19,000 tonnes of uranium.

One analyst said Mr Hunt has done the job asked of him and his departure now makes sense as the project enters a period of hiatus while BHP works through the environmental approval process.

“He was brought in there as the guy to streamline Olympic Dam and I think he has probably done a reasonable job of helping them work out what the priorities are and how many phases they are going to do it in,” said the analyst, who asked not to be named.

“The whole project is going to be on go-slow while they get it through the approval process and even if it was approved tomorrow they are probably not going to be in any hurry to start spending a lot of money.”

BHP hasn’t given a firm timeline for the Olympic Dam expansion and hasn’t updated an out-of-date estimate of the cost of the project of $US6 billion, with analysts now expecting a figure more like $US15 billion.