Studi pengaruh penambahan batubara pada proses roasting reduction bijih nikel saprolit dan pelindian (leaching) dalam larutan asam sulfat 1 molar = Study of coal addition effect on roasting reduction process of saprolitic nickel ore and leaching in sulfuric acid 1 molar - Suprayogi, author (Fakultas Teknik Universitas Indonesia, 2012)