Lithiumabscheidung aus Prozessabwässern mit Hilfe von natürlichen und synthetischen Zeolithen

Lithium, due to its unique physical and chemical properties, is a key raw material for lithium‑ion batteries, whose rapidly growing use is drastically increasing global demand. The geographically limited deposits, environmentally and health-damaging extraction methods, and foreseeable resource depletion make efficient recycling essential. The high graphite content of the black mass causes high chemical consumption in hydrometallurgical recovery processes. Prior graphite removal by froth flotation can reduce chemical consumption but generates large amounts of lithium‑containing wastewater. The aim of this work is to investigate the potential of natural and synthetic zeolites for the removal of lithium from flotation wastewater. Laboratory experiments with different types of zeolite were carried out to evaluate their suitability on the basis of separation rates, zeolite loadings, and regenerability under varying counter‑ion concentrations. The results showed that both natural and synthetic zeolites can generally be used to adsorb and subsequently release lithium. Synthetic zeolites achieve higher loadings (10 - 15 mg g⁻¹) than natural ones (3 - 3.5 mg g⁻¹), which is attributed to their lower Si/Al ratios and higher anionic field strength. The synthetic FAU- (13XBFK) and LTA-type zeolites (4ABFK) exhibit comparable loading, separation and regeneration rates. Lithium uptake correlates with the initial concentration of the respective wastewater and maximum separation rates of 33 – 40 % are achieved. Doubling the zeolite/solution ratio only causes a moderate increase in separation rates of about 11 – 12 percentage points. Desorption using NaCl solutions achieved regeneration rates of 80 – 95 %, with the required Na⁺ concentration depending on the initial loading.