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The focus of casting production on raw materials as a starting point of all industrial value chains is more intense due to legislative and recently the difficulties faced by casting manufacturers. Critical (CRMs) and strategic raw materials (SRMs) are often indispensable inputs for a wide set of strategic sectors including renewable energy, the digital industry, the space and defence sectors and health sector which are all connected to the metal industry. Aluminium and its alloys plays an important CRMs and SRMs. Recycling has become a very important term for environmental protection as it reduces the carbon footprint of the foundry supply chain. The importance of recycling or the use of secondary or scrap raw materials is demonstrated by the fact that only 5% of greenhouse gases are released in the production process compared to the production of primary aluminium. Standard aluminium alloy AlSi 9 Cu 3 (Fe) (EN AC 46000) is widely used in the automotive and transport industry. High mechanical properties such as strength and hardness, as well as elongation and corrosion resistance are the main advantages of AlSi 9 Cu 3 (Fe) alloy. The quality of an alloy is mainly influenced by the properties of the raw material, the melting treatment and the casting technology. The significant use of secondary, i.e. recycled raw material and also of CRM, requires special attention to the chemical composition due to possible deterioration caused by repeated remelting, which can lead to a deterioration of mechanical and other performance properties. A prerequisite for good functional properties is the development of the microstructure. In this work, the influence of completely returned material (secondary raw material—scrap) as the only input charge material for the production of AlSi 9 Cu 3 (Fe) alloys by remelting on the development of the microstructure due to thermodynamic interactions of elements present was investigated. The presence of wide range of alloying elements AlSi 9 Cu 3 (Fe) alloys indicates development α-Al 15 Si 2 M 4 (M = Cr, Fe and Mn), β-Al 5 FeSi, Al 2 Cu and even more complex one such as Al 3 Cu 2 Mg 9 Si 7 using theoretical modelling. Complex solidification path indicates primary aluminium α Al , eutectic phase α Al  + β Si , intermetallic phase on the iron base in Al 5 FeSi and “Chinese script” morphology, intermetallic phase on the magnesium and copper base such as Al 2 Cu and complex intermetallics such as Al 3 Cu 2 Mg 9 Si 7 phase. Thermodynamic effects of elements interaction during solidification sequence significantly influence on solidification path and manner. Although the investigated samples exhibit high tensile strength and elongation, a slight deterioration of the chemical composition, and therefore in thermodynamic effect, has a significant influence on the development of the microstructure. Despite the deterioration of chemical composition, obtained microstructure was correct and, therefore, justified achieved high mechanical properties. Based on the investigation of the thermodynamic, microstructural and mechanical properties of the secondary AlSi 9 Cu 3 (Fe) alloy, the completely return raw material was characterised as a high-quality charge material with good application and recycling potential.

Residual municipal solid waste (RMSW) is a rapidly expanding problem worldwide and a good waste management system could reduce concerns about its correct treatment. The purpose of this study was to characterize RMSW from urban and rural areas with the ultimate goal of estimating the recycling potential of the identified fractions and implementing waste collection and recovery methods according to the type of area that generates them. A direct sampling campaign of RMSW was performed. The results showed that the highest organic waste rate was found in the rural area (11.9%); urban-area-produced RMSW mainly constituted recyclable fractions such as plastic (26.3%), paper (21.8%), glass (3.5%) and metals (3.3%). The physical-chemical characteristics of RMSW showed levels of heavy metals below the detection threshold. The conditions necessary for composting could be met only for the organic fraction coming from rural areas as demonstrated by a pH value of 6.9 and a moisture content of 46.5%. These data will be extended to all the urban and rural areas to design appropriate disposal and/or recovery plants with profitable economic interventions that will lead to a reduction in costs in the planning of the integrated solid waste management.

The generation of solid waste has increased dramatically in China, owing largely to the rapid development and expansion of the Chinese economy. The management of solid waste is critical and becoming a challenge for some cities in China. Waste recycling is an effective solution to solid waste management and seeks to balance ecological sustainability with economic improvements. This study assessed the energy conservation and CO 2 emission reduction potential of solid waste using an embodied energy/carbon model from a life cycle perspective. The results showed that compared with the production of virgin materials, solid waste recycling results in a reduction of 294.2 Mtce in energy consumption, and 614.5 Mt in CO 2 emission is shown in 2017. The recycling of steel waste was the highest contributor, accounting for more than 45% of energy conservation and at least 62% of CO 2 reduction. If 100% recycling of recyclable waste like steel waste and plastic waste can be achieved, energy conservation and CO 2 reduction could reach 551.89 Mtce and 933.69 Mt, respectively, accounting for 12.29% of energy consumption and 8.46% of CO 2 emission. A robust recycling system must be established to achieve the purpose of environment production and resource conservation. The proposed evaluation framework could help in the decision-making process. The waste classification must be promoted to increase waste recovery rate and improve waste reproduction technology to maximize energy conservation and CO 2 emission reduction.

The recycling potential (RP) indicates the ability of building materials to form a closed-loop material flow, that is, the material efficiency during its whole life cycle. Mass timber constructions and concrete buildings vary widely in RP, but the differences are difficult to calculate. This paper proposed a level-based scheme to compare the RP of mass timber and concrete buildings, and a BIM-Eco2soft-MS Excel workflow coupling Material Cycle Database and digital design tools were established to obtain information on building materials, resource consumption, and environmental impact for the RP calculation. Taking a residential building as an example, the difference in RP between mass timber and concrete at the material-level is firstly discussed. Then at the component-level, the RP of the wood structure component and concrete component is compared, and the optimization methods are proposed. Finally, the difference in RP between the mass timber building and reinforced concrete building at the building-level are illustrated. The results show that the RP of mass timber building is higher, and the disassembly ability is better. Within a 100-year service life, the RP of mass timber buildings is 73% and that of the reinforced concrete building is 34%. The total amount of material consumption and waste of the Variant CLT is 837,030 kg and 267,237 kg respectively, which is less than one-third of that of concrete buildings (3,458,488 kg; 958,145 kg). The Global Warming potential (GWP) of these two variants is −174.0 kgCO2/m2 and 221.0 kgCO2/m2 separately, indicating that the Variant CLT can realize negative carbon emissions and gain ecological benefits. A sensitivity analysis is conducted to explore the potential impacts of certain parameters on GWP and RP of buildings. The research can provide the reference for material selection, component design, and RP optimization of mass timber buildings. In addition, new ideas for assessing the potential of circularity as a design tool are proposed to support the transition towards a circular construction industry and to realize carbon neutrality.

Geopolymer concrete (GPC) represents an innovative green and low-carbon construction material, offering a viable alternative to ordinary Portland cement concrete (OPC) in building applications. However, existing studies tend to overlook the recyclability aspect of GPC for future use. Various structural applications necessitate the use of concrete with distinct strength characteristics. The recyclability of the parent concrete is influenced by these varying strengths. This study examined the recycling potential of GPC across a spectrum of strength grades (40, 60, 80, and 100 MPa, marked as C40, C60, C80, and C100) when subjected to freeze–thaw conditions. Recycling 5–16 mm recycled geopolymer coarse aggregate (RGAs) from GPC prepared from 5 to 16 mm natural coarse aggregates (NAs). The cementitious material comprised 60% metakaolin and 40% slag, with natural gravel serving as the NAs, and the alkali activator consisting of sodium hydroxide solution and sodium silicate solution. The strength of the GPC was modulated by altering the Na/Al ratio. After 350 freeze–thaw cycles, the GPC specimens underwent crushing, washing, and sieving to produce RGAs. Subsequently, their physical properties (apparent density, water absorption, crushing index, and attached mortar content and microstructure (microhardness, SEM, and XRD) were thoroughly examined. The findings indicated that GPC with strength grades of C100, C80, and C60 were capable of enduring 350 freeze–thaw cycles, in contrast to C40, which did not withstand these conditions. RGAs derived from GPC of strength grades C100 and C80 complied with the criteria for Class II recycled aggregates, whereas RGAs produced from GPC of strength grade C60 aligned with the Class III level. A higher-strength grade in the parent concrete correlated with enhanced performance characteristics in the resulting recycled aggregates.

With the rapid promotion of new energy vehicles, in-use electric vehicle batteries (EVBs) are becoming an important component of urban mining. This paper analyzed the metal stocks in EVBs in China from 2009 to 2019 using a bottom-up method, which focused on the in-use stock of seven main metals, namely, nickel, cobalt, manganese, lithium, copper, aluminum, and iron, in primary use stage and secondary use stage of three EVB types, namely, lithium nickel manganese cobalt oxide battery (NMC), lithium iron phosphate battery (LFP), and lithium manganese oxide battery (LMO). It was found that the rapid development of electric vehicles (EVs) contributed to a dramatic increase in in-use metal stocks from 0.7 kt in 2009 to 1.1 Mt in 2019. To assess the increase, three scenarios simulating metal stocks in EVBs from 2020 to 2030 were analyzed, namely, baseline, NMC-dominated, and LFP-dominated, and results indicated that metal stocks will reach 20.6 Mt, 23.2 Mt, and 17.9 Mt, respectively, by 2030. Across the scenarios there is little proportional difference in metal stocks between the two use stages. The proportion of the three EVB types correlates to the development trend of EVB technology under each corresponding scenario. Besides, the in-use metal stocks in EVBs have high implied recycling potential and environmental benefit. The recycling potential of these seven metals is 1.0 Mt in 2019, and it will reach 20.0 Mt, 22.6 Mt, and 17.4 Mt, respectively, in 2030 under the three scenarios. The results reveal the current status and evolution characteristics of metal stocks in EVBs in China, and provide data for material flow analysis and life cycle management of EVBs.

In recent years, China’s dominant role in the rare earth market and the associated impacts have strengthened the interest in the recovery of rare earth elements (REE) from secondary resources. Therefore, numerous research activities have been initiated aiming at the recovery of REEs from different types of waste streams, which includes, inter alia, neodymium-iron-boron (NdFeB) magnets. Although several research projects have successfully been completed, most experts do not expect an industrial implementation in Europe within the next years. This article analyses the reasons for this situation, addressing the availability of sufficient amounts of NdFeB wastes, the technology readiness level of the developed processes in Europe, as well as the economic aspects. Based on these analyses, an estimation of a realistic timeframe for the industrial implementation of NdFeB recycling in Europe is deduced and critically discussed.

Minimisation of resources consumption belongs to the main concerns of EU, resulting in the development of strategies for maximizing recycling rates in order to minimize environmental impacts and energy consumption caused by extraction of primary materials. Detailed knowledge about the embedded materials as well as their characteristics of building stocks is crucial in order to enable high recycling rates and low environmental impacts of buildings. In this paper, we will present the results of the funded research project BIMaterial: Process design for a BIM (Building Information Modelling) -based Material Passport. The concept of the BIM-based Material Passport is used for evaluating the recycling potential and environmental impact of materials embedded in buildings. The BIM-based Material Passport assesses all materials including their quantitative and qualitative properties, thus significantly supporting recycling and reduction of environmental impacts. Further, the BIM-supported Material Passport serves as design optimization tool and enables the generation and comparison of variants thus supporting the decision making process. The main aim of this research is to generate a BIM-based Material Passport for the optimization of the building design regarding resources use and documentation of materials, thereby using Building Information Modelling as knowledge base for geometry and material properties and coupling to further databases for assessment of ecologic footprint and recycling potentials. Thereby a framework for modelling and the methodology for the semi-automated generation of the BIM-based Material Passport will be proposed.

Waste characterization is the first step to a successful waste management system. This paper explores the trend of solid waste generated on a university campus (Longzi Lake Campus of Henan Agricultural University) in China and the factors that influence the potential for recycling of the waste. Face-to-face interviews were carried out for 12 consecutive months on a campus in central China, and 416 interviewees were questioned. It was found that 7.32 tonnes of solid waste were generated on the campus each day, of which 79.31% were recyclable. The characterization of major waste streams are discussed, and the results are compared with comparable data from five universities in a range of other countries (Mexico, Canada, Malaysia, Nigeria, and Ethiopia). The annual growth of GDP per capita in China over the past five years before the research appeared to play an important role in the increasing of food waste on university campus, and the proportion of food waste is found to have a positive influence on recycling potential.

The solid waste management (SWM) approach for the protection of resources known as “zero waste” (ZW) has become popular in recent years. Waste characterization is the first step to pursuing a comprehensive and sustainable SWM strategy. The aim of this study is to determine the waste characterization and recycling potential of the Istanbul Technical University (Türkiye) Ayazağa Campus before (2019) and after (2022) the ZW management strategy. The campus was divided into four distinctive groups, which are (1) academic (2) administrative (3) dormitory and (4) cafeteria. First, an initial field study was conducted afterwards, the new containers were placed. Students and campus personnel have been trained within the scope of ZW management practices through both in-person and online seminars. The final phase of the study, the second field work, was completed. The waste generation rate in the pilot areas fluctuates between 0.045 and 0.190 kg/cap/day, but it decreases to 0.011–0.117 kg/cap/day in the second field study. The first field study had a potential recycling rate of 76.3%, but then it dropped to 68.2% in the second study. Recycling rate increased from 16.3 to 26.1% over the same period. However, further studies are still required to assess the ZW’s public awareness activities. Consequently, this study enhances the understanding of current SWM performance on campus and provides suggestions to achieve the ZW goal.