Sumitomo Corp has acquired a 30% interest in Usiminas, Brazil's largest maker of flat steel, for $1.93bn.
The deal will help Usiminas to invest up to $2.2bn by 2015 to develop its iron ore assets.
Usiminas mines have potential reserves of 2.6 billion tons of the mineral.
Rio Tinto said it will increase its stake in Ivanhoe Mines from 7.3% to 29.6% for $393m.
OZ Minerals has acquired a 19% interest in Sandfire Resources.
The deal will help OZ Minerals control Sandfire's high-quality Doolgunna project located in Western Australia.
Orofino Gold Corporation said it has acquired a 55% interest in the Mina Azul/La Estrella property with the rights to acquire up to 80%.
Kinross Gold Corporation has completed the acquisition of Underworld Resources.