The effect of addition of sodium sulphate (Na2SO4) to nickel slag pyrometallurgical process with temperature and additives ratio as variablesJuan Patrick, Agus Budi Prasetyo, Badrul Munir, Ahmad Maksum and Johny Wahyuadi SoedarsonoE3S Web Conf., 67 (2018) 03053DOI: https://doi.org/10.1051/e3sconf/20186703053