Vale SA suspended the Alegria mine operation, part of the Mariana iron ore complex in Brazil's Minas Gerais state, as part of preventive measures, it said March 20.
The operation's closure may result in a maximum production impact of about 10 million tonnes per year.
While all of Alegria's structures are stable, the results from preliminary analysis of the stability under stress conditions were inconclusive, and it is not possible to guarantee the structures' stability under such conditions.
Operations at Alegria will resume when the study is complete and stability under stress conditions is assured.
Earlier this week, a Brazilian court ordered the suspension of Vale's Minervino and Cordao Nova Vista dams until the mining major proves the stability of the structures.
The miner has come under scrutiny following the fatal tailings dam burst at its Feijao iron ore mine in Minas Gerais in January.