scholarly journals Status of Recovery of Strategic Metals from Spent Secondary Products

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 673
Author(s):  
Luthando Xolo ◽  
Pulleng Moleko-Boyce ◽  
Hlamulo Makelane ◽  
Nobathembu Faleni ◽  
Zenixole R. Tshentu

The need to drive towards sustainable metal resource recovery from end-of-cycle products cannot be overstated. This review attempts to investigate progress in the development of recycling strategies for the recovery of strategic metals, such as precious metals and base metals, from catalytic converters, e-waste, and batteries. Several methods for the recovery of metal resources have been explored for these waste streams, such as pyrometallurgy, hydrometallurgy, and biohydrometallurgy. The results are discussed, and the efficiency of the processes and the chemistry involved are detailed. The conversion of metal waste to high-value nanomaterials is also presented. Process flow diagrams are also presented, where possible, to represent simplified process steps. Despite concerns about environmental effects from processing the metal waste streams, the gains for driving towards a circular economy of these waste streams are enormous. Therefore, the development of greener processes is recommended. In addition, countries need to manage their metal waste streams appropriately and ensure that this becomes part of the formal economic activity and, therefore, becomes regulated.

2021 ◽  
Vol 13 (6) ◽  
pp. 3553
Author(s):  
Philippe Nimmegeers ◽  
Alexej Parchomenko ◽  
Paul De Meulenaere ◽  
Dagmar R. D’hooge ◽  
Paul H. M. Van Steenberge ◽  
...  

Multilevel statistical entropy analysis (SEA) is a method that has been recently proposed to evaluate circular economy strategies on the material, component and product levels to identify critical stages of resource and functionality losses. However, the comparison of technological alternatives may be difficult, and equal entropies do not necessarily correspond with equal recyclability. A coupling with energy consumption aspects is strongly recommended but largely lacking. The aim of this paper is to improve the multilevel SEA method to reliably assess the recyclability of plastics. Therefore, the multilevel SEA method is first applied to a conceptual case study of a fictitious bag filled with plastics, and the possibilities and limitations of the method are highlighted. Subsequently, it is proposed to extend the method with the computation of the relative decomposition energies of components and products. Finally, two recyclability metrics are proposed. A plastic waste collection bag filled with plastic bottles is used as a case study to illustrate the potential of the developed extended multilevel SEA method. The proposed extension allows us to estimate the recyclability of plastics. In future work, this method will be refined and other potential extensions will be studied together with applications to real-life plastic products and plastic waste streams.


2021 ◽  
Vol 11 (9) ◽  
pp. 3939
Author(s):  
Krzysztof Pikoń ◽  
Nikolina Poranek ◽  
Adrian Czajkowski ◽  
Beata Łaźniewska-Piekarczyk

The purpose of the study presented in this text is to show the influence of COVID-19 on waste management systems and circular economy stream, and their impact on circular economy, particularly the economic impact of the pandemic on the waste management sector, impact on circular economy objectives’ implementation as well as additional challenges like the need for hygienization of waste streams during different implementation efforts, such as changes in the municipal solid waste market and different waste processes of their disposal. Additionally, some methods—such as thermal treatment—which seemed to be not fully aligned with the circular economy approach have advantages not taken into account before. Incineration of higher volume of waste affects the waste structure and will change some of the circular economy objectives. The analysis was carried out on the example of the Polish market.


Author(s):  
Mulinari Jéssica ◽  
Júnior Afonso Henrique da Silva ◽  
Oliveira Carlos Rafael Silva de ◽  
Júnior Francisco Wilson Reichert

Oily wastewater from agro-industries can cause severe environmental and public health damages if unproperly treated. The conventional methods have several limitations for the treatment of oily wastewaters since the oil fraction can cause pipe clogging and biomass washout during the biological step. Based on this, the use of lipases can increase the oil removal efficiency of the treatments, minimizing operational problems,and improving the performance of the biological process. Lipases can also be used for the valorization of the oily wastewaters, transforming these waste streams intovaluable compounds, such as biodiesel, lubricants, antioxidant agents, etc. The use of wastes for the production of value-added compounds followsthe circular economy approach, minimizing the generation of residues and potential environmental liabilities. Thus, this study aims to give a general overview of themain topics related to thetreatment and valorization of oily wastewaters using lipases. The main characteristics of oily wastewaters from agro-industries areaddressed, as well as the most used conventional techniques for their treatment. Some relevant information about the enzyme lipaseisalso discussed to give the reader a background about how these enzymes can be applied for the treatment and transformation of oily wastes.


2019 ◽  
pp. 114-119
Author(s):  
Valeriy V. Piven ◽  
Vladislav S. Shchelkonogov

Assessment of the quality of separation of hydrocarbon raw during its field preparation is necessary to determine the efficiency of the entire technological process of preparation. The absence of complex criteria for assessing the quality of separation for multi-stage processes does not allow one to obtain unambiguous solutions in justifying the process flow diagrams and equipment for separation. We have analyzed the typical technological scheme of separation of hydrocarbon raw materials and existing criteria for separation processes. It is proposed to use the criterion for a comprehensive assessment of the separation processes of hydrocarbon raw materials, allowing calculating the efficiency of the process, taking into account the possible production of intermediate fractions and their qualitative composition


2021 ◽  
Vol 255 ◽  
pp. 01026
Author(s):  
Oleksii Hutsaliuk ◽  
Iuliiа Bondar ◽  
Nataliіа Sereda ◽  
Oksana Babych ◽  
Inna Shchoholieva

In the modern world, the question of the interaction of society and nature is one of the most acute problems among those facing humanity. Today, rapid economic development is causing a significant increase in the use and, consequently, depletion of natural resources. This necessitates the search for a new economic model that could break the link between economic growth and the depletion of natural resources. The study substantiates the theoretical aspects of eco-tourism as an important component of the strategy of sustainable development of tourism in Ukraine. The priority directions of sustainable development of tourism in the context of modernization of economic activity of Ukraine are outlined. The main directions of greening of the tourist sphere are considered. The main functions and principles of eco-tourism are formed and the relevance of the research and the need to develop prospects for the development of eco-tourism in Ukraine are substantiated. The concept of circular economy is a new economic model that manages the development of ecotourism, which allows to resolve the growing contradiction between the need to meet the growing needs of tourists and the limited number of natural, social, economic resources of host destinations in a deteriorating environment.


1928 ◽  
Vol 18 (2) ◽  
pp. 129-143 ◽  
Author(s):  
T. A. Rickard

During the Republican Period a number of mining districts were exploited in the territory that the Romans annexed. Mines in conquered countries that had belonged to the former rulers became the property of the Roman people, and others were acquired by confiscation or forced purchase from private owners. But the industry was not entirely a State monopoly: on the contrary, a number of mines remained in private hands, more particularly those yielding the base metals—copper, lead and tin—whereas those that yielded the precious metals—gold and silver—were retained by the State. Under the Empire the mines became a special object of bureaucratic concern: as mineral wealth had been the spoil of conquest, so in due course it became the prize of usurpation.


Author(s):  
Atilio Armando Savino ◽  
Ernesto de Titto

A general picture of waste management in Argentina is presented, taking into consideration the obligations of the state to guarantee the collection of household waste and to dispose of it in authorized sites and the generator's responsibility on the management of hazardous waste. Separate boxes are presented to present the activities performed by organized waste pickers and by CEAMSE, a state-owned company responsible for waste disposition in the metropolitan area of Buenos Aires. Waste management is essential for a sustainable development agenda. As witnessed in Argentina, this requires (1) closing open dumpsites, (2) a reliable and complete waste collection service, and (3) proper treatment of all waste streams. It is thus clear the need to (1) promote a circular economy; (2) tackle the management of organic waste; (3) ensure the adequate control and treatment of hazardous waste; (4) promote a suitable set of policies, regulations, and economic instruments; (5) select the best available technologies; and (6) formalize the informal phase of recycling.


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