The high Australian dollar and weak nickel and alumina prices caused the company to recognise a $1.2 billion impairment at Nickel West and a $1.6 billion impairment on the Worsley assets in the 2013 financial year results yesterday.

BHP has flagged overcapacity in nickel and alumina to continue.

Speaking to investors after the release of the results, Mackenzie reiterated the company’s four pillars – iron ore, copper, petroleum and coal – but stopped short of mentioning any sort of exit from nickel or aluminium.

“These businesses are running very much for cash and they receive no major investment in capital,” Mackenzie said.

“They are challenged always to remain cash positive.”

Mackenzie said the businesses weren’t a “distraction to management”

But he said the divisions had been under stress for quite some time, though some positives could come from that.

“Some of the best ideas for improving productivity and managing costs come from these businesses and we’re working very hard to transfer them right across our company,” Mackenzie said.

Mackenzie put manganese in the same category, saying there were no plans to expand and the company would consolidate existing operations.

The aluminium, manganese and nickel division contributed the lowest amount to group revenue of any division at $9.2 billion.

Potash is still considered a potential fifth pillar for the company, as demonstrated by a further $2.6 billion investment in the Jansen project in Canada, announced yesterday.

Mackenzie said the investment in further works gave BHP the option to enter the potash market.

“But only when the time is right,” he said.

There was talk Uralkali’s recent exit from a potash cartel could change BHP’s opinion on the project but its long-term outlook of 2-3% per annum growth to 2013 remained unchanged.

“We have a long-stated preference for transparent pricing mechanisms that truly reflect the supply and demand fundamentals of any given commodity on any given day,” Mackenzie said.

“In the case of potash, our projections have always assumed a shift away from the current market dynamic.”

And BHP may not go it alone at Jansen.

“We may also sell a minimum stake to one or more minority parties,” Mackenzie said.

He said that decision would be more focused on enhancing performance over easing capital requirements, pointing to the healthy relationship with Rio Tinto at Escondida.

He added that he saw a straightforward relationship with a partner that could bring something unique to the table.

BHP last traded 2.3% lower at $A35.68.