Anglo-Australian mining giant Rio Tinto Thursday announced a $14 billion writedown on its Mozambique coal assets and ailing aluminum business, prompting its chief executive to resign.

Rio said it expected non-cash impairments of about $3 billion relating to its Mozambique coal project acquired in 2011, and a further $10 to $11 billion related to its aluminum assets, in its annual results due Feb. 14.

"The Rio Tinto board fully recognizes that a writedown of this scale in relation to the relatively recent Mozambique acquisition is unacceptable," said Chairman Jan du Plessis.

"We are also deeply disappointed to have to take a further substantial writedown in our aluminum businesses, albeit in an industry that continues to experience significant adverse changes globally."

Du Plessis said CEO Tom Albanese had stepped down effective immediately "by mutual agreement with the Rio Tinto board" and would be succeeded in the top job by Rio Tinto's iron ore chief Sam Walsh.

Doug Ritchie, who led the acquisition of the Mozambique assets, which were previously known as Riversdale Mining Limited, had also stood down, he said.

No Lump Sum Payout

Neither would get a lump sum payout or outstanding bonuses. They would formally leave the company on July 16 to ensure a smooth transition.

"While I leave the business in good shape in many respects, I fully recognize that accountability for all aspects of the business rests with the CEO," Albanese said.

The announcement comes a day after the mining giant unveiled record production in 2012 and beefed up expansion plans for its flagship Australian iron ore operations.

The chairman said Rio's underlying business and balance sheet "remain in good health, and we are taking decisive action to improve our competitive position further with an aggressive cost reduction plan".

Rio's unpopular $38 billion acquisition of Canadian firm Alcan in 2007 has cost it dearly, with lagging profits from the metal eating into its bottom line and seeing full-year earnings slump 59% in 2012 to $5.8 billion.

An impairment charge of $8.9 billion from the aluminum business saw Albanese forgo his bonus last year.

Market Worsened in 2012

Rio said conditions in the aluminum market had worsened further in 2012, with a rally in some currencies compounding high raw material and energy costs.

In Mozambique, developing infrastructure to support its new coal assets was proving more challenging than anticipated, the miner said.

"These infrastructure constraints, combined with a downward revision to estimates of recoverable coking coal volumes on the tenements, have led to a reassessment of the overall scale and ramp-up schedule of [the project], and consequently to the impairment announced today," Rio said.

Du Plessis thanked Albanese and Ritchie for their lengthy service to the company -- more than 30 years in the outgoing CEO's case -- and noted Ritchie's "invaluable work in developing our relationships in China."

A slowdown in China and debt woes in Europe and the United States have weighed on mining companies in the past 12 months, with projects delayed or shelved as commodity prices have plunged on a drop in demand.

Copyright Agence France-Presse, 2013