Vale SA evacuated communities in Barão de Cocais in Minas Gerais state after independent auditors warned that the inactive Sul Superior dam at its Gongo Soco iron ore mine is in critical condition and could collapse any time.
The company said March 23 that it raised the warning to level three as a preventive measure. About 500 people were evacuated near the area in February.
The development comes nearly two months after the fatal dam tailings breach at the Feijao iron ore mine, which killed at least 300 people.
In a separate release, Vale said it was working to clean the Paraopeba river after a series of laboratory tests confirmed that the tailings that contaminated the river are non-hazardous.
The company said it was now negotiating with environmental agencies to build dikes and barriers to prevent more dam tailings from being carried to the river.