Recovering Value from End-of-Life Batteries by Integrating Froth Flotation and Pyrometallurgical Copper-Slag Cleaning

Abstract

In this study, industrial lithium-ion battery (LIB) waste was treated by a froth flotation process, which allowed selective separation of electrode particles from metallic-rich fractions containing Cu and Al. In the flotation experiments, recovery rates of ~80 and 98.8% for the cathode active elements (Co, Ni, Mn) and graphite were achieved, respectively. The recovered metals from the flotation fraction were subsequently used in high-temperature Cu-slag reduction. In this manner, the possibility of using metallothermic reduction for Cu-slag reduction using Al-wires from LIB waste as the main reductant was studied. The behavior of valuable (Cu, Ni, Co, Li) and hazardous metals (Zn, As, Sb, Pb), as a function of time as well as the influence of Cu-slag-to-spent battery (SB) ratio, were investigated. The results showcase a suitable process to recover copper from spent batteries and industrial Cu-slag. Cu-concentration decreased to approximately 0.3 wt.% after 60 min reduction time in all samples where Cu/Al-rich LIB waste fraction was added. It was also showed that aluminothermic reduction is effective for removing hazardous metals from the slag. The proposed process is also capable of recovering Cu, Co, and Ni from both Cu-slag and LIB waste, resulting in a secondary Cu slag that can be used in various applications.

Utilization of Scrap Metals as Reductants for Improved Ni and Cu Recoveries in Copper Smelting

“…The experimental technique included sample melting with added Al or Al-Mg reductant piece, rapid quenching in brine, SEM-BSE (scanning electron microscope -backscattered electrons) imaging and direct-phase analyses with EPMA (electron probe micro-analyzer). This drop-quenching technique has been used widely for phase equilibrium [e.g., [17][18][19] and minor element distribution studies [e.g., [20][21][22], and recently also in few kinetic studies [8,[23][24][25][26][27]. In the studies by Ruismäki et al [24][25][26] and Avarmaa et al [27], reduction kinetics were investigated for DON slag (Direct-Outokumpu-Nickel) with different reductants under nickel slag cleaning conditions.…”

“…Various rate-controlling steps in an aluminothermic reduction have been considered: a chemical reaction, a penetration of [16] molten aluminum into slag phase, and a diffusional transfer in slag phase [7,8]. The reductant-slag interface was irregular and unstable, in addition to spontaneous exothermic reactions at the interface causing dynamic condensed phase flow and temperature imbalance (Marangoni flow).…”

“…The time interval for all this to occur was extremely short, within 5 min according to their observations. Rinne et al [8] studied aluminum-rich battery scrap as a reducing agent for industrial copper smelting slag at 1300 °C under Ar. They found that Cu concentration in slag decreased 0.3 wt% after 60 min reduction period and that many hazardous metals were removed efficiently from the slag.…”

A Study on the Effect of Particle Size on Li-Ion Battery Recycling via Flotation and Perspectives on Selective Flocculation

“…During direct recycling processes, shredding, crushing, and sieving are usually applied to produce a stream containing the high-value electrode components, commonly referred to as "black mass." Subsequently, the separation of anode and cathode should be performed by a physical separation operation, among which froth flotation has been considered as an interesting option by several authors [11][12][13][14][15][16][17][18][19][20][21][22]. Flotation is a unit operation that exploits differences in the wettability of materials.…”

A simple methodology for the quantification of graphite in end-of-life lithium-ion batteries using thermogravimetric analysis

“…Following these procedures, the quantification of graphite in battery waste is inexact and difficult. In LIB recycling processes, a simple graphite characterization is needed since it affects the efficiency of operations such as flotation, 17 pyrometallurgy, 32 or hydrometallurgy. 33 …”