Mining giant BHP Billiton  said...production at its Samarco iron ore mine in Brazil...is unlikely to resume before the end of the year.The news comes as Brazil’s federal prosecutors opened...an investigation into alleged environmental crimes by Roberto Carvalho, chief executive of Samarco Mineração SA, related to the deadly tailings dam burst in November last year. Such probe is independent of a $6.2 billion lawsuit the company and its partner Vale are currently facing for what has been billed the worst environmental disaster in Brazil's history. The firms had agreed on a $2.2bn settlement in March, but Brazil's Superior Court responded to an appeal from the Federal Prosecutor's Office by issuing an interim order suspending its ratification.