Abstract
Due to the increasing demand for battery raw materials, such as cobalt, nickel, manganese, and lithium, the extraction of these metals, not only from primary, but also from secondary sources, is becoming increasingly important. Spent lithium-ion batteries (LIBs) represent a potential source of raw materials. One possible approach for an optimized recovery of valuable metals from spent LIBs is a combined pyro- and hydrometallurgical process. The generation of mixed cobalt, nickel, and copper alloy and lithium slag as intermediate products in an electric arc furnace is investigated in part 1. Hydrometallurgical recovery of lithium from the Li slag is investigated in part 2 of this article. Kinetic study has shown that the leaching of slag in H2SO4 takes place according to the 3-dimensional diffusion model and the activation energy is 22–24 kJ/mol. Leaching of the silicon from slag is causing formation of gels, which complicates filtration and further recovery of lithium from solutions. The thermodynamic study presented in the work describes the reasons for the formation of gels and the possibilities of their prevention by SiO2 precipitation. Based on these findings, the Li slag was treated by the dry digestion (DD) method followed by dissolution in water. The silicon leaching efficiency was significantly reduced from 50% in the direct leaching experiment to 5% in the DD experiment followed by dissolution, while the high leaching efficiency of lithium was maintained. The study takes into account the preparation of solutions for the future trouble-free acquisition of marketable products from solutions.
Highlights
High lithium leaching efficiencies close to 100% were achieved after 30 min of leaching at 20 ◦ C using both H2 SO4(ia) + Al2 (SO4) concentrations
As the leaching temperature increases, the time required to leach lithium gradually decreases to 15 min at 40 ◦ C and 60 ◦ C and to five minutes at 80 ◦ C
Lithium slag recycling methods were investigated in this paper
Summary
Lithium-ion batteries (LIBs) are currently considered as one of the most important energy storage systems, which is reflected in a wide range of applications, especially for portable devices [1,2,3,4,5,6,7].Due to the extensive electrification expected in the field of electromobility, batteries will have another key role in the future ensuring the transition towards a climate-neutral economy [8].In addition to the implementation of electromobility and their widespread use for portable applications, Metals 2020, 10, 1558; doi:10.3390/met10111558 www.mdpi.com/journal/metalsMetals 2020, 10, 1558 lithium-ion batteries are indispensable as intermediate storage for the stabilization of decentralized power systems [2,3,4,5,9,10]. Lithium-ion batteries (LIBs) are currently considered as one of the most important energy storage systems, which is reflected in a wide range of applications, especially for portable devices [1,2,3,4,5,6,7]. As a result of increasing applications of lithium-ion batteries, a significantly higher demand for battery containing critical or strategic raw materials, such as cobalt, lithium, and nickel, is to be expected. Those crucial metals are only available in limited quantities and are currently obtained mainly from primary sources [2]. Recycling is an essential aspect of closing the entire substance cycle of LIBs and securing the supply of raw materials for new battery production
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