Enabling the recycling of rare earth elements through product design and trend analyses of hard disk drives

Hard disk drives consist of a complex mix of various materials. While Aluminum, Copper and Steel are easy to separate, actual recycling processes dilute containing rare earth elements to non-recoverable grades in other material streams. To enable future recycling of these materials an in-depth analysis of hard disk drives from Desktop PCs and Notebooks was carried out. Furthermore, possible recycling strategies for rare earth elements were derived and the recycling potential was assessed. The results show high concentrations of Neodymium (22.9 ± 2.8 %), Praseodymium (2.7 ± 2.2 %) and Dysprosium (1.4 ± 1.5 %) in the magnets. Various types of alloys are applied for different technical or economic reasons. Also a dependency from manufacturing dates was evidenced. Furthermore, Cerium (0.5 %) and Neodymium (0.2 %) were determined in printed circuit boards. Test disassemblies of hard disk drives showed a complicated structure and thereby a difficult access to the NdFeB magnets. This applies explicitly for the spindle motor magnets, which hold the main share of applied Dysprosium. A WEEE collection analysis shows an amount of about 12.7t magnets from hard disk drives from PCs in Germany in 1 year. Put-on-market data predict decreasing shares of hard disk drives from Desktop PCs and significantly increasing amounts of Notebook components in WEEE

Challenges for critical raw material recovery from WEEE : the case study of gallium

Gallium and gallium compounds are more frequently used in future oriented technologies such as photovoltaics, light diodes and semiconductor technology. In the long term the supply risk is estimated to be critical. Germany is one of the major primary gallium producer, recycler of gallium from new scrap and GaAs wafer producer. Therefore, new concepts for a resource saving handling of gallium and appropriate recycling strategies have to be designed.This study focus on options for a possible recycling of gallium from waste electric and electronic equipment. To identify first starting points, a substance flow analysis was carried out for gallium applied in integrated circuits on printed circuit boards and LED used for background lighting in Germany in 2012. Moreover, radio amplifier chips (integrated circuits) were investigated in detail to deduct first approaches for a recycling of such components. An analysis of recycling barriers was carried out in order to investigate general opportunities and risks for the recycling of gallium from chips and LED. Results show, that significant gallium losses arose during the production and the waste management. 93 ± 11 %, equivalent to 43,000 ± 4,700 kg of the total gallium potential were lost over the whole process until applied in electronic goods. The largest share of 14,000 ± 2,300 kg gallium was lost in the primary production process. The refining process was connected to additional 6,900 ± 3,700 kg and the chip and wafer production to 21,700 ± 3,200 kg lost gallium. Due to low collection rates, further 400 ± 200 kg of gallium were not recycled. Due to the fact, that no recycling of gallium from WEEE exists, all gallium is lost in the current waste management system. A thermal pre-treatment of the chips, followed by a manual separation allowed an isolation of gallium rich fractions, with mass fractions up to 35 %. Here, gallium loads per Chip were between 0.9 and 1.3 mg. Copper, gold and arsenic were determined as well. The pyrometallurgical copper route might be an option for gallium recycling. A recovery of gold and gallium in combination with copper is possible due to a compatibility with this base-metal. But, a selective separation prior to this process is necessary. Diluted with other materials, the gallium content would be too low and the recovery not feasible any more. The recycling of gallium from chips applied on printed circuit boards and LED used for background lighting is technically complex. Recycling barriers exist over the whole recycling chain. A forthcoming commercial implementation is not expected in nearer future. This applies in particular for gallium bearing chips

Geosmin synthase ges1 knock‐down by siRNA in the dikaryotic fungus Tricholoma vaccinum

Abstract Genetic manipulation for generating knock‐out experiments is essential in deciphering the precise function of a gene. However, dikaryotic fungi pose the inherent challenge of having two allelic versions of each gene, one in each nucleus. In addition, they often are slow‐growing and do not withstand protoplasting, which is why Agrobacterium tumefaciens ‐mediated transformation has been adapted. To obtain knock‐out strains, however, is not feasible with a mere deletion construct transformation and screening for deletions in both nuclear copies. Hence, a convenient method using chemically synthesized dicer substrate interfering RNA (DsiRNA) for posttranscriptional interference of targeted mRNA was developed, based on the fungal dicer/argonaute system inherent in fungi for sequence recognition and degradation. A proof‐of‐principle using this newly established method for knock‐down of the volatile geosmin is presented in the dikaryotic fungus Tricholoma vaccinum that is forming ectomycorrhizal symbiosis with spruce trees. The gene ges1 , a terpene synthase, was transcribed with a 50‐fold reduction in transcript levels in the knockdown strain. The volatile geosmin was slightly reduced, but not absent in the fungus carrying the knockdown construct pointing at low specificity in other terpene synthases known for that class of enzymes

Potentials and Barriers for Tantalum Recovery from Waste Electric and Electronic Equipment

Circular economy approaches aim to close material cycles along the value chain. As such, the circular economy can be a long-term strategy to mitigate the risks of critical raw material (CRM) supply. Tantalum, with a current end-of-life recycling rate of less than 1%, has been intermittently discussed as critical. Even though the specificity of tantalum applications and high-mass fractions of tantalum in relevant components provide good boundary conditions, recycling barriers hinder the successful implementation of recycling technologies. With this case study, we identify potentials and barriers for implementing the recovery of CRM, using the example of tantalum. To this end, information about visually identifiable tantalum capacitors (VICs) and printed circuit boards (PCBs) in various equipment types was obtained by disassembly campaigns for mobile phones, smartphones, tablets, notebooks, desktop personal computers, flat screen monitors, servers, etc., and the chemical analyses of resulting fractions. Results show great differences in the application of tantalum in various equipment types. Because of this, the tantalum potential of put-on-market (POM) or of waste electric and electronic equipment (WEEE) devices differs between products and regions. Worldwide, the highest POM tantalum flows originate from desktop computers, but in Germany they originate from notebooks. A focus on particular products leads to higher yields in recycling and supports circular economy approaches. Recycling of tantalum from WEEE is generally possible. But an accurate separation of tantalum from PCBs is not feasible solely by separation of VICs. This process also leads to the loss of silver. Further, this study reveals potential miniaturization trends, decreasing the use of VICs, with an anticipated substitution of tantalum with niobium. These barriers impede long-term recycling strategies for tantalum aimed at establishing a circular economy

Assessment of element-specific recycling efficiency in WEEE pre-processing

Pre-processing is a crucial step to ensure the efficiency of subsequent processes and the quality of recyclates. The efficiency of pre-processing can be affected by high losses to undesignated output fractions. Standard batch tests usually provide mass balances and are a good proxy for bulk materials balances (iron/steel, aluminum, plastics). This article aims at harmonizing methodologies and recommends a strategy for further study in pre-processing on a plant scale. We have developed an “extended batch test” method, which should help to • describe the fates of materials and elements, • assess the quality of output fractions, • identify access points for critical metals and other valuable elements to enable their recovery. A methodical approach was compiled with common material flow analysis methods and an extended set of methods, which improve the reliability via the assessment of uncertainties. This applies to systematic effects and random effects. This extended batch test was performed with a 40 Mg Waste Electrical & Electronic Equipment (WEEE) batch to trace the flows of industrial base metals, precious metals and critical metals in a WEEE pre-processing plant. Results show that one-third of the input was separated and sorted manually, while the remaining material was subsequently crushed and automatically sorted. Copper and precious metals are distributed to various output fractions but are most concentrated in the sorting residues. Critical metals like cobalt and rare earth elements are mainly concentrated in the manually sorted materials but also appear in the ferrous metals scrap and the shredder light fraction

Potential and recycling strategies for LCD panels from WEEE

Indium is one of the strategically important materials, which have been characterized as critical by various industrialized countries. Despite its high relevance, only low recycling rates are realized. Its main application is in indium tin oxide (ITO), which is used in the production of liquid crystal displays (LCD). However, recovery strategies for indium from LCDs are not yet being implemented in recycling practices. Although LCDs consist of a sandwich compound with additional materials such as glass (80% ± 5%) and polarizer foils (20% ± 5%), recently published recycling approaches focus mainly on the recovery of indium exclusively. This study, first of all, provides information about the quantity and quality of the materials applied in the LCD panels of the various equipment types investigated, such as notebooks, tablets, mobile phones, smartphones, PC monitors, and LCD TVs. The highest indium mass fraction per mass of LCD was determined in mobile phones and the least indium was found in smartphones. Additionally, we found the significant use of contaminating metals like antimony, arsenic, lead, and strontium in the glass fraction. Thus, specific recovery strategies should focus on selected equipment types with the highest indium potential, which is directly related to the sales of new devices and the number of collected end-of-life devices. Secondly, we have developed and successfully tested a novel recycling approach for separating the sandwich compound to provide single output fractions of panel glass, polarizer foils, and an indium concentrate for subsequent recycling. Unfortunately, the strongly varying content of contaminating metals jeopardizes the recycling of this output fraction. Nonetheless, economic recycling approaches need to address all materials contained, in particular those with the highest share in LCD panels such as polarizer foils and panel glass

Sticking together: inter-species aggregation of bacteria isolated from iron snow is controlled by chemical signaling

Marine and lake snow is a continuous shower of mixed organic and inorganic aggregates falling from the upper water where primary production is substantial. These pelagic aggregates provide a niche for microbes that can exploit these physical structures and resources for growth, thus are local hot spots for microbial activity. However, processes underlying their formation remain unknown. Here, we investigated the role of chemical signaling between two co-occurring bacteria that each make up more than 10% of the community in iron-rich lakes aggregates (iron snow). The filamentous iron-oxidizing Acidithrix strain showed increased rates of Fe(II) oxidation when incubated with cell-free supernatant of the heterotrophic iron-reducing Acidiphilium strain. Amendment of Acidithrix supernatant to motile cells of Acidiphilium triggered formation of cell aggregates displaying similar morphology to those of iron snow. Comparative metabolomics enabled the identification of the aggregation-inducing signal, 2-phenethylamine, which also induced faster growth of Acidiphilium. We propose a model that shows rapid iron snow formation, and ultimately energy transfer from the photic zone to deeper water layers, is controlled via a chemically mediated interplay

Attraction pheromone of the benthic diatom Seminavis robusta : studies on structure-activity relationships

Recently the first pheromone of a marine diatom was identified to be the diketopiperazine (S,S)-diproline. This compound facilitates attraction between mating partners in the benthic diatom Seminavis robusta. Interestingly, sexualized S. robusta cells are attracted to both the natural pheromone (S,S)-diproline as well as to its enantiomer (R,R)-diproline. Usually stereospecificity is a prerequisite for successful substrate-receptor interactions, and especially pheromone perception is often highly enantioselective. Here we introduce a structure-activity relationship study, to learn more about the principles of pheromone reception in diatoms. We analyzed the activity of nine different diketopiperazines in attraction and interference assays. The pheromone diproline itself, as well as a pipecolic acid derived diketopiperazine with two expanded aliphatic ring systems, showed the highest attractivity. Hydroxylatoin of the aliphatic rings abolished any bioactivity. Diketopiperazines derived from acyclic amino acids were not attrative as well. All stereoisomers of both the diproline and the pipecolic acid derived diketopiperazine were purified by enantioselective high-performance liquid chromatography, and application in bioactivity tests confirmed that attraction pheromone perception in this diatom is indeed not stereospecific. However, the lack of activity of diketopiperazines derived from acyclic amino acids suggests a specificity that prevents misguidance to sources of other naturally occurring diketopiperazines

Data availability and the need for research to localize, quantify and recycle critical metals in information technology, telecommunication and consumer equipment

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.The supply of critical metals like gallium, germanium, indium and rare earths elements (REE) is of technological, economic and strategic relevance in the manufacturing of electrical and electronic equipment (EEE). Recycling is one of the key strategies to secure the long-term supply of these metals. The dissipation of the metals related to the low concentrations in the products and to the configuration of the life cycle (short use time, insufficient collection, treatment focusing on the recovery of other materials) creates challenges to achieve efficient recycling. This article assesses the available data and sets priorities for further research aimed at developing solutions to improve the recycling of seven critical metals or metal families (antimony, cobalt, gallium, germanium, indium, REE and tantalum). Twenty-six metal applications were identified for those six metals and the REE family. The criteria used for the assessment are (i) the metal criticality related to strategic and economic issues; (ii) the share of the worldwide mine or refinery production going to EEE manufacturing; (iii) rough estimates of the concentration and the content of the metals in the products; (iv) the accuracy of the data already available; and (v) the occurrence of the application in specific WEEE groups. Eight applications were classified as relevant for further research, including the use of antimony as a flame retardant, gallium and germanium in integrated circuits, rare earths in phosphors and permanent magnets, cobalt in batteries, tantalum capacitors and indium as an indium–tin-oxide transparent conductive layer in flat displays.BMBF, 033R087A, r³ - Strategische Metalle, Verbundvorhaben: UPGRADE - Integrierte Ansätze zur Rückgewinnung von Spurenmetallen und zur Verbesserung der Wertschöpfung aus Elektro- und Elektronikaltgeräten, TP1: Übergreifendes Stoffstrommanagement und Design für Recyclin