Pengaruh Jumlah Kandungan Sulfur (2,68 & 5%S) Dalam Reduktor Antrasit Dengan Variasi Jumlah (Stoikiometri 0,0625-0,25) Terhadap Proses Reduksi Selektif Bijih Nikel Laterit Jenis Saprolit = Effect of Sulfur Content in Reductant on Selective Reduction Process of Saprolitic Nickel Ore: at Various Coal Addition of 0.0625, 0.125 and 0.25 of Stoichiometry