Forecasting quantities of critical raw materials in obsolete feature and smart phones in Greece: A path to circular economy.

Mobile phones represent an ever-increasing waste stream due to the increasing ownership and short lifetime. In particular, smartphones are among the most valuable e-waste because of their extremely high content of numerous key metals, specifically in the printed circuit board and magnets. As feature and smart phones contain different key metals at different concentrations, it is important to distinguish between the two phone types to make reliable estimations. This study presents estimations of obsolete mobile phones quantities, generated in Greece in 1995-2035 and the Critical Raw Materials (CRMs) and Precious Metals (PMs) embedded in them, making a differentiation between feature and smart phones. The dynamic material flow analysis is adopted, the lifespan is evaluated by the Weibull distribution and future sales are predicted by the logistic model incorporating phases of growth, saturation and decline. Then, the future wastes are predicted by the Market Supply A model. According to the results, the generation of obsolete smartphones is constantly increasing, while the waste flows of feature phones are declining. Efficient recycling of obsolete phones (1995-2020) can cover the demand for key metals (Au, Pd, Co) in the new smartphones for more than a decade in Greece, while the demand for Ag, Sb, Si, Zn, Be, Ti will be covered for more than 15 years. In 2020-2035 the accumulated amounts of CRMs and PMs, only from the smartphone waste, will be 1292.02 and 14.11 tonnes, respectively. The findings can contribute to the management of a valuable e-waste category closing the loop between resources-products-wastes.

Dynamic estimation of future obsolete laptop flows and embedded critical raw materials: The case study of Greece.

The coronavirus pandemic has turned school and university learning system from classroom-based to exclusively online all over the world. As this change is accompanied by a spike in demand of laptops, an excessive amount of obsolete devices will be witnessed in the near future. Laptops are the most valuable e-waste category containing a high content of numerous critical raw materials, thus their waste management is crucial. Considering the impact of the coronavirus pandemic on the laptop lifespan, the future quantities and pieces of obsolete laptops in Greece are estimated (2016-2040), as well as the critical raw materials (CRMs) and precious metals (PMs) embedded in them, to illustrate the potential of recovering useful resources, thus contributing to a circular economy. To this end, dynamic material flow analysis is adopted, lifespan distribution is evaluated and future sales are predicted by the logistic model utilizing a bounding analysis. Then the future End-of-Life (EoL) laptop quantities are estimated taking time-varying parameters into consideration such as penetration rate, population, laptop weight and lifespan. This study is a dynamic estimation that avoids using average values adopted from literature that are not country specific. The provided information is useful for implementing national plans, improving the management of the most valuable category, EoL laptops, enhancing resources efficiency and contributing to a circular economy. The coronavirus pandemic has a similar impact on laptop sales in other countries, affecting their future laptop waste as well.

Valorisation of soil contaminated by petroleum hydrocarbons and toxic metals in geopolymer mortar formation.

Until the complete transition to a renewable energy sources based economy, the potential environmental hazards associated with petroleum refinery industries affecting water, air and soil seek sustainable solutions. In the present study contaminated soil from a refinery is used as an alternative source for producing useful building materials by geopolymerization. To this end, soil remediation by thermal desorption was initially applied. Thermal treatment was performed between 60 and 250 °C for short time intervals (10-30 min) in order to remove organic pollutants (Total Petroleum Hydrocarbons, TPHs and Polycyclic Aromatic Hydrocarbons, PAHs). Physical, chemical analyses, mineral phase composition, as well as thermogravimetric analysis were employed to characterize the sample. Moreover, removal efficiency of TPHs and PAHs was evaluated. Subsequently, the treated soil presenting the maximum elimination of TPH and PAHs was used in geopolymer mortar formation aiming to stabilize the toxic metals (TMs) and produce a possible profitable material. For geopolymer synthesis the substitution of metakaolin (MT) by treated soil at 0, 50, 70 and 100% was tested. The produced specimens were evaluated based on the 28 day compressive strength and metals leaching. Results showed that the geopolymer constructed by 50% MT-50% remediated soil at 250 °C for 30 min, had negligible content of organic pollutants, TMs were immobilized and exhibited increased strength thus giving significant recycling benefits. Valorisation of industrial residues to produce building materials is a promising solution for sustainable waste management.

Evaluation and comparison of pre-treatment techniques for recovering indium from discarded liquid crystal displays.

Over the last years, emerging incentives for secondary production of high tech-metals, found in e-waste, are created because of their increasing demand and economic issues associated with their primary production. Due to the very low share of these metals in e-waste, pre-treatment methods can result in an output fraction rich in the metals of interest and may, therefore, be essential. To this scope, the present article evaluates and compares the efficiency of four different pre-treatment approaches containing various steps for recovering indium (In) from liquid crystal displays (LCDs) in laptop computers. The pre-treatment steps, used in various combinations, are (a) dry mechanical crushing and sieving, (b) pyrolysis, (c) thermal shock and (d) gravimetric process. Also, in all approaches, liquid crystals were removed from the samples, before applying the mechanical crushing step, as these are toxic and potentially harmful to human health and the environment. The removal was achieved by ultrasonic irradiation or mild agitation and optimized in terms of time, temperature and solvent type and concentration. Then, the feasibility of each pre-treatment approach was evaluated based on two parameters: (a) the content of In in the resulting sample after pre-treatment and (b) the separated mass share (%) with larger indium content as compared to the original LCD panel. The results showed that In is highly liberated in the fractions consisting of finest particles (<25 µm and <53 µm) after dry mechanical crushing and sieving with a maximum content of 234 mg/kg, which is twice as much as in the raw material. However, these particles represented only about 14 wt% of the original LCD panel mass. On the contrary, thermal shock results indicated that this was the most efficient pre-treatment approach, as both the content of In and the separated LCD mass (%) remained in high levels. Finally, some economic aspects associated with the processes are presented.