The miners were released on Thursday, two days after they were seized.
A spokesman for the company, Companhia Vale do Rio Doce (CVRD), said the Indians had been demanding better public healthcare.
The spokesman said the hostages were released in good health after talks between the National Indian Agency (FUNAI) and Indians from the Guajajara tribe.
Agency officials had proposed that the Indians travel to Brasilia to negotiate directly with the president of the National Health Foundation, which provides medical services for Indians.
On Tuesday, the Indians blocked a railway line linking CVRD's iron ore mines at Carajas in the northern state of Para to a port at Sao Luis in Maranhao state in northeast Brazil.
In November, Indians invaded a town near Carajas, threatening to paralyse production, and in early December they blocked an iron ore export railway line in central Minas Gerais state operated by CVRD.
In both cases, they withdrew after a few days of talks.