Regulations released in August required Vale, which lost its spot as the world's top iron producer to Rio Tinto (ASX, LON, NYSE: RIO) earlier this year, to "decharacterize" or modify some small internal dikes at nine dams similar to the one that burst in January 2019. At least 25 of them belong to Vale, whose Córrego do Feijão iron ore mine's tailings suffered a catastrophic failure last year, killing 270 people