For seven years Cleveland's Hanna Mining Co. has been marooned in frustration on top of some of the world's richest mountains of iron ore, unable to move more than a trickle of it onto the world market. Despite a contract with the Brazilian government empowering it to tap 300 million tons of high-grade ore that it owns in Minas Gerais state, Hanna has been harassed by a succession of political obstacles, is still battling a court decree annulling its mining rights. With the Brazilian economy as well as the climate for foreign investment improving (see THE HEMISPHERE), Hanna last week...