Integrating Flotation and Pyrometallurgy for Recovering Graphite and Valuable Metals from Battery Scrap

Ronja Ruismäki,Ari Jokilaakso,Tommi Rinne,Pekka Taskinen,Anna Dańczak,Rodrigo Serna-Guerrero

doi:10.3390/met10050680

Abstract

Since the current volumes of collected end-of-life lithium ion batteries (LIBs) are low, one option to increase the feasibility of their recycling is to feed them to existing metals production processes. This work presents a novel approach to integrate froth flotation as a mechanical treatment to optimize the recovery of valuable metals from LIB scrap and minimize their loss in the nickel slag cleaning process. Additionally, the conventional reducing agent in slag cleaning, namely coke, is replaced with graphite contained in the LIB waste flotation products. Using proper conditioning procedures, froth flotation was able to recover up to 81.3% Co in active materials from a Cu-Al rich feed stream. A selected froth product was used as feed for nickel slag cleaning process, and the recovery of metals from a slag (80%)–froth fraction (20%) mixture was investigated in an inert atmosphere at 1350 °C and 1400 °C at varying reduction times. The experimental conditions in combination with the graphite allowed for a very rapid reduction. After 5 min reduction time, the valuable metals Co, Ni, and Cu were found to be distributed to the iron rich metal alloy, while the remaining fraction of Mn and Al present in the froth fraction was deported in the slag.

Highlights

Since their commercial launch in 1991, lithium-ion batteries (LIBs) have become the dominant power source technology for a variety of electronic devices, from electric vehicles (EVs) to laptops, due to their superior electrochemical properties such as low self-discharge rate and high energy density [1].The prospected demand of LIBs is expected to grow annually by 25% from 180 GWh in 2018 to 2600GWh in 2030 [2]
If the subsequent processing requires lower iron concentration in the metal alloy, iron can be selectively oxidized from the metal alloy by using air or oxygen and adding silica flux enables the formation of a fayalitic slag [40]
Sodium roasting and subsequent water leaching has been proposed by Li et al [42] for recovering lithium from pyrometallurgical slag, while the recovery of manganese from slags has been studied by Ayala and Fernández [43] and Baumgartner and Groot [44]

Summary

Introduction

Since their commercial launch in 1991, lithium-ion batteries (LIBs) have become the dominant power source technology for a variety of electronic devices, from electric vehicles (EVs) to laptops, due to their superior electrochemical properties such as low self-discharge rate and high energy density [1].The prospected demand of LIBs is expected to grow annually by 25% from 180 GWh in 2018 to 2600GWh in 2030 [2]. The prospected demand of LIBs is expected to grow annually by 25% from 180 GWh in 2018 to 2600. The major driving factor for the growing demand is attributed to the transportation sector shifting to a low-emission fleet [2]. An increasing demand of LIBs sets pressure on both the upstream processes (e.g., mining and refining) to extract raw materials and manufacture components, and downstream processes (e.g., second life and recycling) to maximize the recovery of secondary raw materials. Depending on the vehicle model, the LIB in an EV can make up 40% of the total costs, making it the most valuable component [3].

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Results

Conclusion