(Poster session) Processing & Material

[P048B] Eco-friendly recovery of Cu, Ni, and Co from smelter slag via sulfation roasting using pyrite-rich flotation tailings

○Bobur Gayratov^{1[Student presentation: Doctoral course]}, Labone Godirilwe¹, Sanghee Jeon¹, Atsushi Shibayama¹ (1. Akita University)

Keywords:slag, roasting, leaching

Wastes such as slags and tailings generated during non-ferrous metal production often contain significant concentrations of unrecovered valuable metals, representing a promising secondary resource for critical metal supply. This study proposes an eco-friendly hydrometallurgical approach to recover copper (Cu), nickel (Ni), and cobalt (Co) from smelter slag using pyrite-rich flotation tailings as a sulfur source for low-energy sulfation roasting, followed by water leaching.The process was designed to selectively convert Cu, Ni, and Co into water-soluble sulfates while stabilizing Fe in the residue as insoluble oxides. Key operational parameters, including roasting temperature, duration, slag-to-pyrite ratio, additive dosage, and leaching conditions were systematically investigated. Optimal metal recovery was achieved under the following conditions: sulfation roasting at 600 °C for 4 hours with a slag-to-pyrite mass ratio of 1:1, and sodium metabisulfite (SMBS) added at 30 wt% of the slag/pyrite mixture. This was followed by atmospheric water leaching at 25 °C for 2 hours with a solid-to-liquid ratio of 0.1 g/mL and agitation at 180 rpm.Under these optimized conditions, extraction efficiencies of Cu, Ni, and Co reached 80.5%, 75.6%, and 87.1%, respectively. Iron dissolution was effectively minimized, with only 3.9% leached, and the remainder retained in the residue primarily as hematite. This novel slag–tailings co-treatment strategy not only enables efficient recovery of valuable metals from two waste streams simultaneously but also significantly reduces environmental impact, offering a sustainable solution for metallurgical waste management.