Recovery of gold, other metallic and non-metallic components of full-size waste random access memory

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 degrees 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. (C) 2017 Elsevier Ltd. All rights reserved.