Comparing the costs and benefits of virgin and urban mining

Resource and environmental management are shaping our society and economy.Virgin mining is rapidly becoming unsustainable as primary resources are in increasingly short supply and energy consumption continues to increase.Urban mining through a circular economy has emerged as a promising option for securing copper and aluminum resources.However,the sustainability and viability of this circular economy industry are heavily dependent on its profitability.Here,we demonstrate the economic benefits of urban mining for anthropogenic minerals:e-waste,end-of-life vehicles,waste wiring and cables.The material and cost flows associated with urban mining are deeply examined.Through life cycle cost and cost-benefit analysis,the cost of obtaining one ton of copper or aluminum is found to be,on average,3,000 US$or 1,660 US$,which is significantly lower than the cost of virgin mining.Moreover,in terms of the costs and benefits,copper may differ tremendously from aluminum depending on the type of anthropogenic mineral.Some additional regulations or policies enactment need to reinforce the urban mining and circular economy.

Recycling and recovery of spent copper-indium-gallium-diselenide(CIGS)solar cells:A review

Copper-indium-gallium-diselenide(CIGS)is a fast-evolving commercial solar cell.The firm demand for global carbon reduction and the rise of potential environmental threats necessitate spent CIGS solar cell recycling.In this paper,the sources and characteristics of valuable metals in spent CIGS solar cells were reviewed.The potential environmental impacts of CIGS,including service life,critical material,and material toxicity,were outlined.The main recovery methods of valuable metals in the various types of spent CIGS,including hydrometallurgy,pyrometallurgy,and comprehensive treatment processes,were compared and discussed.The mechanism of different recovery processes was summarized.The challenges faced by different recycling processes of spent CIGS were also covered in this review.Finally,the economic viability of the recycling process was assessed.The purpose of this review is to provide reasonable suggestions for the sustainable development of CIGS and the harmless disposal of spent CIGS.

Clustering the Stations of Bicycle Sharing System

Bicycle sharing system has emerged as a new mode of transportation in many big cities over the past decade.Since the large number of bicycle stations distribute widely in the city,it is difficult to identify their unique attributes and characteristics directly.Oriented to the real bicycle hire dataset in Hangzhou,China,the clustering analysis for the bicycle stations based on the temporal flow data was carried out firstly.Then,based on the spatial distribution and temporal attributes of calculated clusters,visual diagram and map were used to vividly analyze the bicycle hire behavior related to station category and study the travel rules of citizens.The experimental results demonstrate the relation between human mobility,the time of day,day of week and the station location.

A MOF/poly(thioctic acid)composite for enhanced gold extraction from water matrices

With the fast generation of electronic waste(e-waste)and the increasing depletion of metal resources,“urban mining”that can selectively recover gold from secondary resources has attracted great interest.Construction of materials with high extraction capacity and satisfying selectivity in complex aqueous-based matrices still remains challenging.Here,a novel metal-organic framework/polymer composite(Fe-BTC/poly(thioctic acid),denoted as Fe-BTC/pTA)has been newly synthesized and applied for selective gold recovery in different matrices(river water,seawater,and leaching solution of e-waste).Benefiting from the high specific surface area and suitable pore sizes as well as the rational design of active sites,the composite exhibits high adsorption capacity(920 mg/g),high removal efficiency(>99%),fast kinetics(below 0.1 ppb within 10 min),and good applicability in complex matrices,which are better than those of most reported sulfur-containing adsorbents.Solid-state metallic gold with high purity can be effectively enriched due to the high recyclability and long-term stability of the composite.The material after adsorption can be further applied as a heterogeneous catalyst for water remediation due to the in situ generated gold nanoparticles by the redox reaction between Au(III)ions and the S-containing groups in the composites.

Spatiotemporal dynamics of city-level WEEE generation from different sources in China

China stands as one of the leading producers of waste electrical and electronic equipment(WEEE),facing significant challenges in managing the substantial volumes generated.Despite existing regulations,the informal treatment of WEEE persists in some areas due to inadequate recycling networks at the city level.Consequently,there is a critical need for a detailed geographical mapping of WEEE generation to address improper disposal practices effectively.This study introduces the cMAC–EEEs(city Material Cycles and Manufactured Capital–EEEs)database,providing estimates of WEEE generation across approximately 300 prefecture-level cities from 1978 to 2017.It focuses on five commonly used types of electrical and electronic equipment(refrigerators,air conditioners,washing machines,computers,TVs)originating from three key sources(urban residents,rural residents,enterprises).The findings reveal(1)significant spatial variation in WEEE generation within China,with eastern and central city clusters identified as hotspots,particularly for urban residents and enterprises,while the western region exhibits the highest growth rate in WEEE generation,notably among rural residents.(2)The growth in obsolete computers and air conditioners is prominent,especially in rural areas and among enterprises,whereas the generation of obsolete TVs,washing machines,and refrigerators is leveling off and expected to decrease in some urban areas.(3)Enterprises account for a substantial portion of WEEE generation,though uncertainties exist,necessitating further refinement.The study highlights that less developed regions lack adequate recycling facilities,with specific limitations in refrigerators and air conditioners recycling capabilities.To enhance WEEE management,it advocates for increased interregional collaboration and capacity building in less developed areas.Additionally,the regulation of WEEE from private enterprises requires improvement.At the product level,a greater focus on recycling practices for refrigerators and air conditioners is recommended.

Perspectives for the recovery of rare earths from end-of-life fluorescent lamps

This vision paper discusses the advantages and disadvantages of the three main options for the recycling of rare-earth ele- ments from end-of-life fluorescent lamps： （1） direct re-use of the lamp phosphor mixture; （2） separation of the lamp phosphor mixture into the different phosphor components; （3） recovery of the rare-earth content. An overview is given of commercial activities in Europe in the domain of recycling of materials from end-of-life fluorescent lamps and the recovery of rare earths from these lamps. The collection of end-of-life fluorescent lamps is currently driven by a legal framework that prohibited the release of mercury to the environment. The contaminations of the lamp phosphor powders by mercury and by small glass particles of crushed fluorescent lamps are limiting factors in the recycling process. Research should be directed to an advanced clean-up of the reclaimed lamp phosphor fraction, and in particular to the removal of mercury and glass fragments. The recovery of rare earths from the lamp phosphors could be facilitated by taking advantage of the differences in resistance of the different lamp phosphors by chemical attack by inorganic ac- ids and bases.