LONDON (AP) â¿¿ Anglo-Australian mining group Rio Tinto PLC posted a $3 billion loss for 2012 after taking a $14 billion writedown from its aluminum business and the acquisition of a coal company in Mozambique. The loss â¿¿ compared to a profit of $5.8 million in 2011 â¿¿ came after two senior executives stepped down last month after acknowledging that developing infrastructure in Mozambique was more challenging than expected. It also needed to cut its estimates of recoverable coal volumes. Underlying earnings dropped 40 percent to $9.3 billion because of falling commodities prices. Revenue from operations declined 40 percent to $16.5 billion. Sam Walsh, the new chief executive, announced plans to cut costs by $5 billion at the world's third-largest diversified mining company.