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Rasoul K Nekouei, Farshid Pahlevani, Ravindra Rajarao, Rabeeh Golmohammadzadeh, and Veena Sahajwalla (2018)

Two-step pre-processing enrichment of waste printed circuit boards: Mechanical milling and physical separation

Journal of Cleaner Production, 184:1113-1124.

Printed circuit boards (PCBs), one of the most complex components of e-waste, contain different metallic and non-metallic components. Recycling of waste PCBs is an important issue, from both aspects of hazardous waste management and recovery of valuable materials. In this study, for the first time, a mechanical-physical separation method for recovery of metallic elements of waste PCBs without any chemical or/and thermal processes was introduced. Two milling stages were applied to enhance the liberation degree, followed by a physical flotation process for enrichment. Based on the elemental analysis, the total metal concentration increased by 75% after the second milling in coarser particle size classifications and ceramic components has decreased significantly. Phase identification techniques confirmed that the ceramic portion is mainly CaO+SiO2+Al2O3, which generally exist inside the boards as glass fibres. Using Fourier transform infrared spectroscopy (FTIR) spectra 3 nominees of phenoxy resin, poly vinyl acetate and vinyl chloride were suggested as the major polymer content of the crushed waste PCBs. Scanning electron microscopy (SEM) demonstrated higher degree of liberation in the higher meshes for metallic and non-metallic components but it was lower for fibre glasses. The thermal pyrolysis using infrared gas analyser proved that the most volatile substances are not simple greenhouse gases such as CO, CO2 and CH4. Eventually, beneficiation using bromoform + acetone resulted in two phases of high density (sunk) and low density (float), in which the former one was enriched in metals excluding Al and Sn, and the latter one was almost depleted from metals.

Bromoform, E-waste, Enrichment, Milling, Separation, Waste PCB

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The Material Limits of Energy Transition: Thanatia

Antonio Valero Capilla, Alicia Valero Delgado and Guiomar Calvo

This book provides a holistic view of raw mineral depletion in the context of renewable energy transistion.

The material limits Thanatia


Thanatia. Los límites minerales del planeta

mites minerales del planeta

 Antonio Valero Capilla and Alicia Valero Delgado interviewed by Adrián Almazán

We need a material transition, not only energetic, that restores nature and effectively reuses materials. Gaia must be cared for by extending life on Earth and slowing its degradation towards Thanatia.

Thanatia los limites


Thermodynamics for Sustainable Management of Natural Resources

Cover Thermodynamics

Wojciech Stanek (Editor)

This book examines ways of assessing the rational management of nonrenewable resources. Integrating numerous methods, it systematically exposes the strengths of exergy analysis in resources management.

Thanatia: The Destiny of the Earth's Mineral Resources

Cover Thanatia

A Thermodynamic Cradle-to-Cradle Assessment by (author): Antonio Valero Capilla and Alicia Valero Delgado

Is Gaia becoming Thanatia, a resource exhausted planet? For how long can our high-tech society be sustained in the light of declining mineral ore grades, heavy dependence on un-recycled critical metals and accelerated material dispersion? These are all root causes of future disruptions that need to be addressed today.