...Four months after the collapse of an iron ore dam caused the largest environmental disaster in Brazilian history, the mining companies involved agreed Wednesday to pay billions of dollars in the coming years to alleviate the devastated region.  "This agreement is an important step in supporting the long-term recovery of the affected communities and the environment," said Andrew Mackenzie, chief executive officer of BHP Billiton, in a statement...Some $1.1 billion will be distributed in the next three years through a foundation that will create programs to restore the environment and indemnify local communities, said BHP. Some $4 billion more will be provided in the next 15 year[s]...