Recovery of Cobalt from Acid Mine Drainage and Spent-Battery Processing Effluent by Ambient-Temperature Vacuum Phase Separation

Cobalt is a structurally constrained critical material: it has no dedicated mine, being recovered almost entirely as a by-product of copper and nickel operations, and its supply chain narrows to two chokepoints — the Democratic Republic of the Congo, which accounts for approximately 73% of world mine output, and China, which controls approximately 70–78% of global refining. In 2025 the DRC introduced export quotas, capping 2026 exports at 96,600 t against world production of roughly 220,000 t in 2024, and the market inverted from surplus into structural deficit, with cobalt metal moving from about USD 56/kg at the start of 2026 to approximately USD 60/kg by April 2026. This paper addresses a supply source that is neither quota-bound nor refinery-bound: cobalt already dissolved in aqueous streams. Two such streams are examined — acid mine drainage together with leach solutions, raffinates and tailings waters from the Central African Copperbelt, and the effluent of spent-battery processing. We describe the application of ambient-temperature deep-vacuum phase separation (the Arbok Critical-Materials Recovery platform) to the recovery of Co2+ from these streams, present a module-level techno-economic model, and quantify the sensitivity of project economics to feed concentration, which in the Katanga region spans four orders of magnitude. For a 200 m3/day module at a conservative design basis of 0.2 g/L Co, the model yields approximately 14 t of cobalt per year and a total contribution of approximately USD 1.45M per year including copper and nickel co-products, recycled water and avoided acid-drainage neutralization. On a raffinate-grade feed of 1 g/L, the cobalt line alone rises to approximately 70 t per year.