Abstract
Increasing recovery of critical raw materials (CRMs) from waste electrical and electronic equipment (WEEE) is a strategic priority to mitigate supply risks. Today, CRM recovery rates are generally low, with increases requiring new recovery processes and interface optimisation with pre-processing to ensure appropriate material flows for efficient recovery are generated. Here, results from an industrial trial to increase CRM recovery from WEEE are presented to inform development of pre-processing strategies which generate such material flows. Au, Ag, Co, Ga, Mg, Nb, Ru, Pd, Ir, Y, Nd, Sb, Ta and W are identified with XRF in components of a range of WEEE samples including within individual printed circuit board (PCB) components. CRM distribution in PCBs is mapped by visual inspection with reference to this data. Cost-effective methods to disassemble WEEE; isolate CRM bearing components, and upgrade/concentrate CRMs are evaluated for industrial adoption. A guillotine is found most suitable for LCD disassembly and separation of Au edge-contacts from PCBs, while cryocracking is best for isolation of internal components of digital media devices. Thermal PCB disassembly with a solder bath for simultaneous SMD removal and subsequent sieving to sort SMDs thereby concentrating CRMs for recovery is a promising approach. Microwave ashing of PCBs to concentrate CRMs is promising although off-gas treatment would be required. Recovery potential of identified CRMs from material streams generated is found to be poor due to lack of suitable recovery infrastructure except for precious and platinum group metals in PCBs, but available pyrometallurgical recovery permanently dissipates other CRMs present.
Highlights
The global availability of raw materials is increasingly under pressure due to growing demand and the increasing likelihood of supply bottlenecks
critical’ raw materials (CRMs) identified in samples are differentiated into those which are product specific and those occurring in common components of sample printed circuit board (PCB)
XRF failed to reveal the presence of the rare earth metals (REMs) Dy and Pr known to be present in NIB alloy (Buchert et al, 2012) and Ce, La, Eu, Gd and Tb known to be present in CCFL phosphors (Dupont and Binnemans, 2015; Hobohm et al, 2016)
Summary
The global availability of raw materials is increasingly under pressure due to growing demand and the increasing likelihood of supply bottlenecks. Global resource security is a growing concern, and access to ‘critical’ raw materials (CRMs) has become a priority issue for governments around the world. Accelerating technology innovation cycles and growth in emerging economies has steadily increased demand for raw materials with predictions showing that global resource use could double between 2010 and 2030 (Gislev and Grohol, 2018). All sectors must reduce greenhouse gas (GHG) emissions, and energy efficiency measures contribute the majority of reductions for the transformation, buildings, industry and transport sectors. Such measures require the manufacture and installation of new energy-efficient technologies, and these contain a wide range of CRMs (IEA, 2017). IRENA's ‘REmap Case’ provides a technology roadmap to deliver 71% reduction in global energy-related CO2 emissions by 2050 by reducing energy consumption (from 51 to 38 GJ/cap); increasing renewables share in energy generation (from 25% to 86%); increasing electricity share in total energy consumption (from 29% to 49%); deploying ~1.2 billion passenger
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