SAO PAULO, June 15 (Reuters) - Brazilian steelmaker Gerdau SA said on Thursday it will invest 3.2 billion reais ($666.64 million) by 2026 in a new sustainable mining platform in the Minas Gerais state, a bid to boost its iron ore output while reducing emissions.

The new platform will raise the production capacity of Gerdau's Miguel Burnier mine to 5.5 million metric tons of iron ore per year and is scheduled to start operating at the end of 2025, according to the company.

The project will rely on the dry stacking method for disposal of 100% of the mining tailings, eliminating the need to use a dam, Gerdau said.

"This new sustainable mining platform is also an important initiative in reducing our greenhouse gas emissions, since we will have high quality ore," Gerdau's CEO Gustavo Werneck added in a statement.

Gerdau said it will use the iron ore obtained from the new platform on four steel production units also located in Minas Gerais state.

($1 = 4.8002 reais) (Reporting by Paula Arend Laier; Editing by David Gregorio)