TITLE:
Reductive Leaching of Cobalt Using Sulfuric Acid Plant Effluents: A Pathway to Circularity in the Minerals and Metals Value Chain
AUTHORS:
Emmanuel Ciza Murhabazi, Kaniki Tumba, Emmanuel Alexandre Kasororo, Emmanuel Kalimwera Lungwe, Erick wa Mudiata Koshi
KEYWORDS:
Reducing Agent, Cobalt, Effluents, Sodium Metabisulfite
JOURNAL NAME:
Journal of Minerals and Materials Characterization and Engineering,
Vol.14 No.5,
September
30,
2026
ABSTRACT: This study investigates the potential use of effluents from sulfuric acid production as a reducing agent for cobalt leaching. The aim is to reduce production costs by substituting sodium metabisulfite (SMBS) with effluents rich in sodium bisulfite. Leaching experiments were conducted to determine the most effective reducing-agent dose, and its addition point. The findings show that the reducing agent dose has a significant impact on the cobalt extraction, with optimal yields approaching 90% for both SMBS and effluents at 5 kg of SO2 per ton of ore, with the reducing agent added at t = 1 h. Changes the reducing agent addition point from t = 1 h to t = 0 h had a beneficial effect on copper extraction by avoiding the precipitation of Chevreul’s salt, but they had little effect on cobalt recovery. The results confirm that effluents can be used as a cost-effective alternative to SMBS, as long as they are processed to raise the concentration of bisulfite, even though using raw effluents results in a slightly higher acid consumption.