Anglo, like many miners, shied away from directly trading its own material for decades, selling instead largely through intermediaries such as established trading houses.

That changed in 2013 under Chief Executive Mark Cutifani, as Anglo sought a direct connection with customers to get more value from every tonne of material sold, a move which added more than $400 million to underlying operating profit in two years.

The value of sales made to intermediaries - and not direct to end users - fell from 60 percent in 2012 to less than 10 percent of the total in 2015 - roughly the current level, according to Peter Whitcutt, the Anglo veteran who became chief executive of marketing a year ago.

The group is now close to the limit of the extra cash it can squeeze out per tonne sold, Whitcutt said in an interview last week. But it can still get closer to the needs of commodity end-users, particularly in opaque markets like thermal coal, or targeted markets like minor platinum group metals.

"There is more we can do as we improve the resource-to-market connection and make the most of what we have in the ground," he said, speaking at the group's Singapore office, the base for much of its trading activities.

Demand for fixed-price contracts, for example, has prompted Anglo to develop its capabilities in financial derivatives.

"We sell on a floating price basis, but some customers want a fixed price, so we can put that back to our 'risk neutral' position using financial markets," he said.

Anglo says it will not trade commodities it does not mine and has no plan to invest in warehouses or vessels, though it now has a shipping desk and sees more value to be extracted from better use of those ships.

"We are not expanding into handling third party material or using financial instruments just for the sake of it," Whitcutt said. It does still see some scope to trade material mined by others.

"We have a real capability rooted in Anglo American’s mines and our desire to get full value for our resource."

Anglo is one of several mining companies that have turned to the philosophy of extracting as many marginal gains as possible across operations to improve overall performance at a time of weak prices.