Recovery of gold, other metallic and non-metallic components of full-size waste random access memory. (20th January 2018)

• Record Type: Journal Article
• Authors: Tatariants, Maksym; Yousef, Samy; Denafas, Gintaras; Tichonovas, Martynas; Bendikiene, Regita
• Is Part Of: Journal of cleaner production. Volume 172(2018)
• Page Start: 2811
• Page End: 2823
• Publication Date: 2018-01-20
• Subjects: Recycling -- Waste Printed Circuit Boards -- (WPCBs) -- Random-Access Memory -- (RAM) -- Dissolution -- Dimethylacetamide -- (DMA) -- Woven fiberglass -- Brominated Epoxy Resin -- (BER); Factory and trade waste -- Management -- Periodicals; Manufactures -- Environmental aspects -- Periodicals; Déchets industriels -- Gestion -- Périodiques; Usines -- Aspect de l'environnement -- Périodiques; 628.5
• DOI: 10.1016/j.jclepro.2017.11.132
• Languages: English
• ISSNs: 0959-6526

Abstract

Abstract: In order to increase environmental and economic benefits of waste Random Access Memory (RAM) recycling, this research aims to separate all metallic and non-metallic components of RAM by using chemical treatment and subsequent leaching process to liberate gold from gold-plated components. Chemical treatment was employed to separate metal (copper foils, contacts, through-hole pads) from non-metal by performing organic solvent Dimethylacetamide (DMA) and ultrasonic treatment at a low temperature (50 °C) in order to dissolve Brominated Epoxy Resin (BER) and separate all layers of waste RAMs. The process was carried out in a simple reactor developed specifically for this purpose. After the dissolution process, a rotary decompression evaporator was used to extract epoxy resin from DMA/BER solution and regenerate the solvent. At the same time, leaching by nitric acid was used to liberate gold from parts with high gold concentration, in particular from contacts. SEM-EDS, TGA, DSC, FTIR, and UV-VIS spectroscopy were used to characterize the recovered epoxy resin, metal, and regenerated DMA. Additionally, metallographic microscope was used to examine the DMA/BER solution. The results showed that RAMs were composed of seven layers of plain woven fiberglass, four copper foil layers, conductive tracks, contacts, solder joints of integrated circuits, epoxy resin, and soldermask. Moreover, gold with purity >94% was successfully recovered as a result of applying developed treatment technique with yield ∼12 times higher than traditional milling followed by leaching approach. Highlights: Ultrasonic separation technology was used for separate all components of RAM. The separation process was conducted in a developed reactor. The recycled RAM consisted of seven layers of fiberglass and four metallic layers. Copper was the main metallic element in metallic layers (∼95.4 wt %). The yield of gold was ∼12 times higher than traditional approach.