SAO PAULO, April 16 (Reuters) - Brazilian miner Vale on Tuesday reported growth of 6.1% year-on-year in its first-quarter iron ore production, reaching 70.84 million metric tons, while sales rose 14.7% in the period to 63.83 million tons. (Reporting by Gabriel Araujo and Marta Nogueira; Editing by Kylie Madry)