A Review on Recycling of End-of-Life Light-Emitting Diodes for Metal Recovery

Abstract

The generation of end-of-life light-emitting diodes (LEDs) requires efforts to minimize waste and recycle critical raw elements (gallium, indium, and rare earths). This review critically analyzes recycling processes such as physical, hydrometallurgical, and pyrometallurgical treatments. An insight into gallium compounds (GaN, GaAs) and their influence on recycling strategies is provided. Pre-treatment plays a critical role in dissociating the rigid structure of GaN. The major gaps in recycling are identification, segregation, selective recovery, and limited studies on the elemental flow of toxic arsenic. It is calculated that the processing of 1 ton of LEDs is equivalent to 7.8 tons, 3.2 tons, and 42 tons of primary Ga ore, In ore, and Au ore in metallurgical value, respectively. The market value calculations revealed significant economic values of Au, Ag, and REEs. A recycling flowsheet based on the literature for the holistic recovery of Ga, In, Au, and REEs is proposed.

Recovery technologies for indium, gallium, and germanium from end-of-life products (electronic waste) – A review

“…The influencing parameters for indium, gallium, and germanium recovery are discussed in the present paper. In the leaching process, the most important influencing parameters are pH, the selection and concentration of leaching agent(s), the ratio of solid e-waste samples to liquid in the leaching system, the particle size fraction of samples, reaction time, temperature, and agitation rate (Akcil et al, 2019;Chen et al, 2017;de Oliveira et al, 2021;Fontana et al, 2020;Mir et al, 2022;Tao et al, 2021). Thoughtful optimization of these parameters can exert a profound influence on the dissolution and leaching yields of indium, gallium, and germanium.…”

Effective adsorption of In(iii) from hydrochloric acid solution using hyperbranched polyethyleneimine and sodium chloroacetate modified weakly acidic macroporous resin

“…To further investigate the mechanism of the adsorption process of the adsorbent, the isotherm adsorption data can be fitted by various models. Langmuir and Freundlich are two common isotherm models, the relevant calculation equations are shown in eqn (10) and (11), respectively. 48,49 Langmuir:…”

“…6,9,10 At present, pyrometallurgical and hydrometallurgical methods are the two most important methods for recovering indium. 11,12 The pyrometallurgical method, including smelting and pyrolysis, is an effective way to recover indium. However, the whole process needs to be carried out at high temperature and in a specific environment, which has the problems of the complex process, high energy consumption and high cost.…”

Research on Automotive Scrap Metal Classification Method Using Laser-Induced Breakdown Spectroscopy and Two-Step Clustering Algorithm

“…With the continuous development of the automotive industry and the introduction of new products, the recycling of end-of-life vehicles has become a signi cant challenge. Additionally, the rising prices of iron ore, increasing steel demand, and limited steel production capacity further emphasize the importance of e ciently classifying scrap metals to reduce recycling costs and improve recycling e ciency [1][2][3][4] .…”