bhp laterites arrive

FROM MINING NEWS.

BHP's laterites arrive


Friday, 23 May 2008

BHP Billiton’s Ravensthorpe nickel laterite operation has been officially launched, but full production will not be reached until 2010. Noel Dyson reports from the opening ceremony.

The official opening event today drew a star-studded cast of attendees including BHP chairman Don Argus, Federal Resources and Energy Minister Martin Ferguson and Western Australian Premier Alan Carpenter.

The nickel laterite mine and processing project, though successfully commissioned, is still in its ramping up phase.

However, by 2010 it is expected to hit its full production of 220,000 tonnes of a mixed nickel cobalt hydroxide (MHP). This is equivalent to up to 50,000t of contained nickel and 1400t cobalt a year.

The MHP will then be trucked to Esperance in specially designed stainless steel containers. At the Esperance Port these containers will be loaded onto the BHP-leased ship Spirit of Esperance for the two week voyage to the Yabulu Refinery in Townsville.

This is not the first time mining has come to Ravensthorpe – a town about 560 kilometres from Perth. About 110 years ago gold was discovered there and in the nearby seaside town of Hopetoun. By 1909 the population had hit 3500. In 1911 the rush was over.

The BHP operation, in contrast, has a life of 25 years.

The major miner took the decision to develop Ravensthorpe and expand its Yabulu Refinery in 2004.

It had been anticipated that developing Ravensthorpe would cost $US1.1 billion ($A1.08 billion). That cost eventually blew out to $US2.2 billion.

Argus said that at the time the Ravensthorpe investment had been the largest that BHP had ever embarked upon.

BHP stainless steel president Jimmy Wilson said today the cost blow-out had been a result of the mining boom catching BHP unawares.

When the project was first costed the economy was fairly stable and prices were predictable. The mining boom changed that and also caused Ravensthorpe’s development schedule to be put back.

And it didn’t help that nickel laterite is a challenging ore to process. There have been several attempts in Australia to make it happen. Arguably the most successful has been Minara’s Murrin Murrin project and that has been a struggle.

Wilson said despite this, BHP was confident it had a good understanding of the issues around nickel laterite processing.

“There’s been a lot of work done with those organisations [that have already tried nickel laterite processing] and people from those organisations to ensure all the learnings they had were taken on board,” he said.

“Those learnings have been important not only in the design but also how we’ve structured the organisation and the way it’s operated.”

To ensure Ravensthorpe is a success, BHP has created a team tasked with anticipating problems and coming up with solutions before they become real issues.

BHP also revealed today there could be potential to expand on Ravensthorpe’s capacity although Wilson said the targets the company had set itself were not too onerous.

Nickel laterite will also be a major growth focus for BHP’s nickel business. It has other laterite opportunities in Indonesia and the Philippines, and what it learns at Ravensthorpe could be applied to these projects.

Mining itself is relatively straightforward. Once the deposit’s thin blanket of overburden is cleared – at its thickest it is about 10 metres deep – there is a layer of limonite ore followed by a layer of saprolite ore. The pit will be about 500m wide and about two kilometres long.

The mine has three deposits: Halleys, Hale Bopp and Shoemaker-Levy. Halleys is the first deposit to be exploited and it is expected to provide ore to the processing plant for another five years.

The comet names come from the deposits’ original finder, Comet Resources, which sold out to Billiton in 2001, not long before the giant merged with BHP.

It is in the treatment of the ore that things get tricky.

Ravensthorpe uses a mixture of high pressure acid leaching and atmospheric pressure acid leaching to treat all its ores.

This process is called enhanced pressure acid leaching.

Wilson said BHP’s EPAL process was the only one he knew of that was able to treat both the saprolite and limonite types of ores.

The HPAL part is used to treat the limonite while the atmospheric pressure acid leaching is used to treat the saprolite. Those two treatments together remove about 90% of the nickel from the beneficiated ore.

Besides the ore treatment facilities and mine, the Ravensthorpe site also includes the southern hemisphere’s largest sulphuric acid plant, a power generator and a desalination plant.

Water is pumped 46km from the Southern Ocean to the desalination plant, and the heat generated from the acid plant is used to create steam to run the generator and also desalinate the water.