Recovery Of Raw Materials Research Articles

Effect of mining residues treated with an electrodialytic technology on cement-based mortars

Abstract Mining residues have been accumulated for centuries due to excavation and mining processes, causing environmental degradation worldwide. Their application in cementitious products is a feasible alternative to waste disposal. Electrodialytic technologies can promote a safer reuse of mining residues in the construction sector, coupling economic advantages due to the possible removal of toxic elements and the recovery of critical raw materials. The application of treated mining residues in construction products, namely their effects on physico-mechanical properties, in comparison to raw residues and cement uses needs to be addressed. This work presents a study of cement-based mortars with the incorporation of mining residues treated with an electrodialytic process in comparison to raw mining residues. The replacement percentages studied were 0, 10, 25 and 50% of the binder in volume. Tests were conducted to evaluate fresh and hardened properties of mortars considering physical, microstructural and mechanical performances. Results show the viability of applying mining residues after the electrodialytic treatment as mortars materials in rendering, plastering, joint repointing, bedding masonry or screed requirements, with improved thermal conductivity and eco-efficiency.

Bioleaching to reprocess sulfidic polymetallic primary mining residues: Determination of metal leaching mechanisms

The mining of non-ferrous metals produces the largest volume of metal-containing, extractive waste in Europe, and about 29% of all the waste produced in the EU-28. In the framework of the European project NEMO (Near-zero-waste recycling of low-grade sulfidic mining waste for critical-metal, mineral and construction raw-material production in a circular economy), new ways to valorize sulfidic tailings are being developed through the recovery of valuable metals and critical raw materials and the transformation of the residual in clean mineral fraction to be used for the mass production of cement, concrete and construction products. The first step of the NEMO concept consists of removing the sulfides remaining from primary bioleaching and extracting the metals in the residual material (known as ‘secondary ore’) using either enhanced bioleaching or an alkaline autoclave conversion processes. This paper focuses on one of the project case studies, the secondary ore, obtained from an operating heap leaching plant (Terrafame, Finland). This material still contains several sulfide minerals (pyrrhotite, pyrite, sphalerite, pentlandite, violarite, chalcopyrite) and significant amounts of metals (Zn, Ni, Cu, Co, rare earth elements). The study aimed to characterize the mineralogy of the secondary ore and perform bioleaching in 2 L-stirred tank reactors, with three microbial cultures growing at 42, 48 and 55 °C. These results were compared to abiotic experiments, performed under the same conditions. Nickel was released very quickly, suggesting that part of Ni dissolved in the primary heap was re-precipitated and remained in the secondary ore. By contrast, Cu dissolution was much slower but the kinetics were substantially improved when the temperature was increased to 55 °C. Cobalt dissolution kinetics were highly improved by the bacterial activity, whatever the consortium. This is consistent with the presence of Co in the pyrite in the secondary ore.

Legacy iron and steel wastes in the UK: Extent, resource potential, and management futures

The iron and steel industry has a long tradition of bulk reuse of slags for a range of construction applications. Growing interest in recent years has seen slag resource recovery options extend to critical raw material recovery and atmospheric carbon capture. Full scale deployment of such technologies is currently limited in part by absent or partial inventories of slag deposit locations, data on composition, and volume estimates in many jurisdictions. This paper integrates a range of spatial information to compile a database of iron and steel slag deposits in mainland United Kingdom (UK) for the first time and evaluate the associated resource potential. Over 190 million tonnes of legacy iron and steel slag are present across current and former iron and steel working regions of the UK, with particular concentrations in the north west and north east of England, and central Scotland. While significant potential stockpiles of blast furnace and basic oxygen furnace slag could provide up to 0.9 million tonnes of vanadium and a cumulative carbon dioxide capture potential of 57–138 million tonnes, major management challenges for resource recovery are apparent. Over one third are located in close proximity to designated conservation areas which may limit resource recovery. Furthermore, land use analyses show that many of the sites have already been redeveloped for housing (nearly 30% urban cover). Deposits from recent decades in current or recently closed steel-working areas may have the greatest potential for resource recovery where such ambitions could be coupled with site restoration and regeneration efforts.

Inventory of Wastes Generated in Polish Sewage Sludge Incineration Plants and Their Possible Circular Management Directions

A dynamic development of sewer networks and municipal wastewater treatment plants (WWTPs) leads to the formation a large amounts of municipal sewage sludges (MSSs) which have to be disposed. One of the MSS disposal practices is thermal conversion in mono-incineration plants. Nowadays, there are 11 such installations in Poland, with the total capacity 160,300 Mg d.w. of MSSs per year. This paper presents a comprehensive analysis of wastes generated in Polish MSS mono-incineration plants. As a consequence of MSSs incineration, various types of waste are generated including, for example, bottom and fly ash, dust or solid waste. The most valuable waste is sewage sludge ash (SSA), which can be used in other industries, as fertilizer or construction sectors. In the circular economy (CE) model, SSA should be treated as a secondary source of raw materials, such as phosphates (replacement of nutrients by P-rich ashes in fertilizers) or sand (replacement of sand by ashes in construction materials). Current practices of SSA management include landfilling, recovery at WWTPs or management by external companies (recovery, disposal or collection). To preserve the utility value of SSA, it should be stored selectively, and then directed to raw materials recovery. This creates the possibility of turning waste into a secondary resource, after meeting certain conditions which depend on which product the waste is directed to. Moreover, this waste management practice is recommended in the Polish documents regarding the usage of SSA, and it can strengthen the accomplishment of the European Green Deal, which is the newest roadmap for making the EU’s economy sustainable and circular.

Towards Increased Recovery of Critical Raw Materials from WEEE– evaluation of CRMs at a component level and pre-processing methods for interface optimisation with recovery processes

Increasing recovery of critical raw materials (CRMs) from waste electrical and electronic equipment (WEEE) is a strategic priority to mitigate supply risks. Today, CRM recovery rates are generally low, with increases requiring new recovery processes and interface optimisation with pre-processing to ensure appropriate material flows for efficient recovery are generated. Here, results from an industrial trial to increase CRM recovery from WEEE are presented to inform development of pre-processing strategies which generate such material flows. Au, Ag, Co, Ga, Mg, Nb, Ru, Pd, Ir, Y, Nd, Sb, Ta and W are identified with XRF in components of a range of WEEE samples including within individual printed circuit board (PCB) components. CRM distribution in PCBs is mapped by visual inspection with reference to this data. Cost-effective methods to disassemble WEEE; isolate CRM bearing components, and upgrade/concentrate CRMs are evaluated for industrial adoption. A guillotine is found most suitable for LCD disassembly and separation of Au edge-contacts from PCBs, while cryocracking is best for isolation of internal components of digital media devices. Thermal PCB disassembly with a solder bath for simultaneous SMD removal and subsequent sieving to sort SMDs thereby concentrating CRMs for recovery is a promising approach. Microwave ashing of PCBs to concentrate CRMs is promising although off-gas treatment would be required. Recovery potential of identified CRMs from material streams generated is found to be poor due to lack of suitable recovery infrastructure except for precious and platinum group metals in PCBs, but available pyrometallurgical recovery permanently dissipates other CRMs present.

What waste management can learn from the traditional mining sector: Towards an integrated assessment and reporting of anthropogenic resources

Many organizations in Europe collect data and perform research on municipal solid waste and the secondary raw materials that can be produced from them through recycling, urban mining, or landfill mining. However, the information generated and presented thereby is often highly aggregated, while research activities are many a time isolated. Both reduce the usability of the data and information generated. In order to better structure the knowledge generation on secondary raw materials production from municipal solid waste, we suggest to learn from the traditional raw materials mining industry how to perform an integrated assessment and reporting of anthropogenic resources. This is exemplarily shown for the case of the anthropogenic resource municipal solid waste incineration bottom ash and air-pollution control residues. A network of expert institutions from countries throughout Europe was build up to compile the information on legal and technological aspects for the recovery of different secondary raw materials from these residues, including construction minerals, metals, and salts. We highlight in our article the strength of the combined knowledge of an expert network not only on legal and technological, but also local and site-specific aspects of the recovery of secondary raw materials. By doing so, we hope to kick-off a discussion for how to organize and implement a structure for a better management of knowledge on anthropogenic resources, in order to provide a sustainable supply of secondary raw materials for a greener and more circular economy.

Optimizing AGV Calculation MAP Path of Waste Smoke Recovery

With the emergence of Industry 4.0, Technological reform and technological model innovation will surely be launched in the industrial manufacturing industry. Based on the intelligent development direction explained by Industry 4.0 and the current status of the tobacco industry logistics, AGV for waste smoke recycling is proposed Example map route optimization topic. In the complex operation and maintenance environment of the tobacco industry, unmanned transportation technology is used to automatically recover the residual cigarettes in the wrapping workshop, replacing the traditional manual forklift recycling model. Focusing on the auxiliary production of intelligent production, with the automatic recycling of residual cigarettes as the core, we will further optimize and perfect the intelligent recovery or supply of production waste and other raw and auxiliary materials.

Synergistic adsorption of lanthanum ions and fatty acids for efficient rare-earth phosphate recovery: Surface analysis and ab initio molecular dynamics studies

Rare earth elements (REE) are indispensable in our daily life but they naturally occur in minerals, which are generally difficult to concentrate by the froth flotation method. Considering the significant affinity of lanthanum ions for phosphate species as well as for carboxylate groups, the influence of a lanthanum salt (LaCl3) on the adsorption of carboxylate species on monazite surface [(La,Ce,Nd)PO4] was investigated by bubble/particle adhesion tests, X-ray photoelectron spectroscopy (XPS), and atomistic simulations based on density functional theory (DFT). Both theoretical and experimental results demonstrated that lanthanum ions adsorb on the phosphate groups of monazite surface under the LaClCO3 form with a significant adsorption energy. Also, the hydrophobization of the monazite surface with fatty acids is considerably improved in presence of LaCl3, which is in accordance with DFT calculations: the lanthanum ions pre-adsorbed on monazite surface act as highly attractive adsorption sites for carboxylate collectors. In particular, these bridging cations significantly increase the adsorption energy of carboxylate collectors, from 344 to 420 kJ·mol−1 in absolute value. This synergistic adsorption will allow developing new methods for efficient monazite recovery from complex ores, a promising step for the recovery of critical raw materials.

Electrodialytic Hydrogen Production and Critical Raw Materials Recovery from Secondary Resources

Electrodialytic technologies are defined as treatment processes that promote the removal/recovery of substances in a matrix, based on the application of low-level current intensities. Additionally, along these processes hydrogen is self-generated, allowing them to operationally produce clean energy. This energy carrier is produced due to electrolysis reactions occurring at the cathode end of the electrodialytic reactor, when using inert electrodes. Herein, hydrogen production during the electrodialytic treatment of sewage sludge and mining residues suspensions (coupled with effluent or sewage sludge), at 50 and 100 mA, was assessed. During the electrodialytic treatment of sewage sludge, hydrogen purity production achieved 33%. When effluent or sewage sludge were used as enhancements in mining residues suspensions, hydrogen purity reached 71% and 34%, respectively. Furthermore, a proton-exchange membrane fuel cell was connected to the cathode compartment of the electrodialytic reactor. The electrical energy generated from self-hydrogen produced at 100 mA achieved ≈1 V in all performed experiments. Simultaneously, critical raw materials extraction, namely phosphorus and tungsten, was evaluated. When the process was applied to mining residue suspensions combined with sewage sludge, the highest extraction ratio of phosphorus (71%) and tungsten (62%) was observed.

Hydrogel bacterial cellulose: a path to improved materials for new eco-friendly textiles

In this paper, we present a novel, ecologically friendly technology for the synthesis and modification of kombucha-derived bacterial cellulose in order to produce textiles of desired physicochemical and mechanical properties. The procedure of manufacturing cellulose in the form of a stable hydrogel bacterial cellulose (HGBC) ensures the desired properties for the application of such a material, e.g., in the textile industry. Bacterial cellulose was obtained from a yeast/bacteria kombucha culture (a symbiotic consortium also known as “tea fungus” or SCOBY) that is easy and cheap to breed. The process of bacterial cellulose manufacturing and modification was optimized in order to obtain a maximum recovery of raw materials, minimal energy consumption and ensure the use of only natural and renewable resources. The obtained materials were characterized in terms of their wettability, mechanical properties, and flame resistance. Moreover, the morphology and composition of the materials were determined by using scanning electron microscopy and infrared spectroscopy, respectively. Additionally, it was proven that the HGBC materials might be used to manufacture various articles of clothing using commonly available sewing techniques, which are not adequate for non-modified cellulose-based materials. Finally, the synthesized fabrics were used as wristbands and parts of T-shirts and tested on volunteers to determine a skin-to-skin contact behaviour of the prepared fabrics. The reported results allow for confirming that the HGBC fabric may be used as a new textile and the proposed synthesis method is in accordance with the “green chemistry.”Graphic abstract

Assessment of the Possible Reuse of Extractive Waste Coming from Abandoned Mine Sites: Case Study in Gorno, Italy

Supply of resources, a growing population, and environmental pollution are some of the main challenges facing the contemporary world. The rapid development of mining activities has produced huge amounts of waste. This waste, found in abandoned mine sites, provides the potential opportunity of extracting raw material. The current study, therefore, focuses on testing the validation of a shared methodology to recover extractive waste from abandoned mines, and applies this methodology to a case study in Gorno, northwest Italy. The methods focused on: (1) analyzing the impact of tailings and fine fraction of waste rock (<2 mm) on plants (Cress - Lepidium Sativum) to assess usability of both as soil additive, and (2) recovering raw materials from tailings and coarse fraction (>2 mm) of waste rock, by means of dressing methods like wet shaking table and froth flotation. The results indicated that the fine fraction of waste rock and tailings did not have detrimental effects on seed germination; however, there was marked decrease in plant growth. As for the recovery of raw materials, the coarse waste rock samples, crushed to <0.5 mm, produced a recovery of Cd, Ga, and Zn—as much as 66%, 56%, and 64%, respectively—using the wet shaking table. The same samples when crushed to 0.063–0.16 mm and used for froth flotation produced a recovery of Cd, Ga, and Zn of up to 61%, 72%, and 47%, respectively. The flotation experiment on tailings showed a recovery of Cd, Ga and Zn at pH 7 of 33%, 6% and 29% respectively. The present investigation highlights the methodologies used for extracting raw materials from extractive waste.

A circular approach to the e-waste valorization through urban mining in Rio de Janeiro, Brazil

Electronic waste (e-waste or WEEE) is one of the most critical categories regarding the decision-making for waste management. Brazil is the second major e-waste producer in Americas, after USA, with 1.5 million tones generated annually. However, the absence of adequate system for e-waste reverse logistics are a reality in most of the Brazilian cities. Concerning this hypothesis, we proposed a scenario analysis to support decision-making in e-waste management. This study analyzed the e-waste amount generation, the location of the recycling companies of this segment and the collection routes in the metropolitan region of Rio de Janeiro (MRRJ). Besides, we proposed a set of criteria and indicators to identify the best option for e-waste management. The analysis indicates that Rio de Janeiro is the biggest e-waste producer of the MRRJ, with an amount of approximately 127 ton/day, corresponding to 251 collection points, which represents a high discrepancy in relation to the other municipalities of MRRJ. The findings point out that indicators, such as the Gross Domestic Product (GDP) and Municipal Human Development Index (MHDI), could be used as an alternative for a more accurate analysis for a sustainable urban grid design. This study identified 24 e-waste recycling industries that services the current demand of the MRRJ, most of them concentrated in the central and south portions of the MRRJ, which coincide with the municipalities with the biggest e-waste generation rates. Some hotspots, however, are isolated from the recycling industries, as observed at the MRRJ extremes. In order to provide a better choice for e-waste reverse logistics routes, we proposed 12 indicators, in environmental, economic and social dimensions. Thirty-five hotspots were identified and divided in five main routes according to the recycling industries nearby and the local roads. Urban mining of e-waste seems to be an interesting alternative for secondary raw material recovery, especially in an emerging economy country like Brazil, that consumes huge amounts of electronic devices and demands solutions compatible with environmental law requirements. Hence, this study contributes for a more sustainable development pattern regarding e-waste management in the country, since it reinforces the importance of circularity.

Novel indicators to better monitor the collection and recovery of (critical) raw materials in WEEE: Focus on screens

Currently, in the European Union (EU), e-waste chain performance is assessed by technical indicators that aim to ensure system compliance with collection and recovery targets set by the WEEE Directive. This study proposes indicators to improve WEEE flow monitoring beyond the current overall weight-based approach, including complementary flows and treatment performance. A case study focused on the screen category in France is presented. In 2017, the collection rate of cathode-ray tube screens (CRT) was 68%, while for flat panel display (FPD) generated only 14% was collected. CRT screens have less precious and critical materials than FDP. Thus, elements like cobalt and gold highly concentrated in FPD, have a collection rate two to four times lower than elements such as copper (37%) which represents a high proportion in CRTs. Recycling is the main treatment in France. Nevertheless, the recycling rate per element varies significantly due to the low collection, and also the lack of technology and/or secondary raw materials market. The elements with higher recycling rates are base metals such as copper (28%), followed by precious metals like silver (23%), and gold (13%). Except for palladium, the recycling rate of the critical raw materials targeted in the study ranged from 6% (cobalt) to 0% (e.g. neodymium and indium). The results stress the need for indicators to support the development of WEEE chain from waste management to secondary (critical) raw materials suppliers.

Circular economy model framework in the European water and wastewater sector

One of the key elements in the transformation towards a circular economy (CE) is providing more sustainable practices for resources and waste management. Improvement actions focused on transformation towards a CE should be targeted at all groups of materials and waste. As water is essential for human survival and well-being and plays a significant role in sustainable development (SD), the actions related to the reuse of water and the recovery of raw materials from wastewater and other water-based waste should be taken. The paper presents a proposition for a new CE model framework in the water and wastewater sector, which includes the six following actions: reduction—prevent wastewater generation in the first place by the reduction of water usage and pollution reduction at source; reclamation (removal)—an application of effective technologies for the removal of pollutants from water and wastewater; reuse—reuse of wastewater as an alternative source of water supply (non-potable usage), recycling—recovery of water from wastewater for potable usage; recovery—recovery of resources such as nutrients and energy from water-based waste, and rethink—rethinking how to use resources to create a sustainable economy, which is `free` of waste and emissions. The novelty of the proposed CE model framework is that it presents possible ways of implementing CE principles in the water and wastewater sector, with a strong emphasis not only technological but also organisational and societal changes. Application of the proposed model may help to further transform the European economy to the CE model. Moreover, the indicated model can be significant tool supporting an assessment of local or regional progress towards CE in the water and wastewater sector and further environmental management and planning.

Decentralized Planning of Lithium-Ion Battery Production and Recycling

Recycling of lithium-ion batteries enables the recovery of scarce raw materials with lower economic, ecological, and social impacts compared to the primary production. However, the full potential of the recycling can only be reached through cooperation between forward and reverse supply chain. Due to the autonomy of the different companies, the decision-making process in such cooperation is decentralized. In practice, this leads to inefficiencies. Therefore, this contribution aims develop models for the decentralized planning of production and recycling, which are suitable for the application of lithium-ion batteries, and use them to analyze inefficiencies based on a case study.

Critical Raw Materials Recovery through Bio/Hydrometallurgy from Secondary Resources

Demand for critical raw materials (CRMs) to be used in consumer products is growing rapidly.[...]

Circular economy transition in Italy. Achievements, perspectives and constraints

Abstract This study evaluates the transition to CE in Italy on a sample of 292 organizations after introducing a brief overview of the main principles of CE (reduction, repair, reuse, recover, remanufacturing, recycling) as well as how they are implemented at macro level. With regard to the sample we analysed the data related to the circular business models adopted by the selected organizations, with also a focus on CE implementation at the meso levels given that it also entails the adoption of cooperation strategies between companies. The results point out that several types of organizations (companies for profit and non-profit, research centres/universities) are involved in the transition to CE with different sizes (small, medium and large) and economic sector’s specializations. Recycling resulted to be, among the so called 6R practical framework, the preferred practice of most of the organizations involved over the whole supply chain, from the collection of post-consumption waste to the recovery, recycling and production of secondary raw materials. The other “principles” such as repair, reuse, remanufacturing are progressing well, mainly within small companies, where several laboratories deal with the reuse of products and their selling in second hand shops, or in the recovery and redistribution of food surplus and the remanufacturing of personal computers. The “reuse”, in particular, has constantly increased in the last five years thanks to the on-line sales. Some companies also deal with the dissemination of the CE culture (by means of different channels such as cultural events, actions and best practices to avoid plastic abuse, repair cafes, urban regeneration and urban mining projects) that includes the diffusion of all its principles and concepts such as in particular the prevention and reduction of waste and the maintenance of the value of products. In that, such companies and their activities provide with the opportunity of shifting the concept of CE beyond the current social political debate centred on recycling. Hopefully, this will contribute to unlock and promote the preventive vision of the CE.

Towards a circular supply chain for PV modules: Review of today's challenges in PV recycling, refurbishment and re‐certification

AbstractPhotovoltaic (PV) waste, associated to the exponentially growing PV installations on global scale, presents today an emerging environmental challenge but also brings unprecedented and multifold value creation opportunities. In this context, significant PV business and research and development (R&D) efforts shift towards establishing a more sustainable, environmentally friendly and economically viable end‐of‐life (EoL) management for PV modules: including recycling, recovery of raw materials, repair/refurbishment and even re‐use of decommissioned or failed PV modules. In the CIRCUSOL project, PV partners aspire to formalize the repair/refurbish and re‐use value chains in the PV industry and propose a circular business model, based on a product‐service system (PSS). Towards these goals, this review study introduces the relevant research groundwork, a status overview and today's R&D and business challenges in PV recycling, repair/refurbishment and re‐certification aspects for second‐life PV modules. The topics and the relevant reported literature are examined from both circular economy and technology perspective. The review indicates a considerable technological and operational know‐how in PV EoL management that already exists and continuously evolves in mature PV markets. On the other hand, R&D in repair/refurbishment of decommissioned and/or failed PV modules remains scarce, and best practices and commercial services for reliability testing/re‐certification and trading of second‐life PV modules are neither standardized nor consolidated into any PSS or business model.

“Smart Is Not Smart Enough!” Anticipating Critical Raw Material Use in Smart City Concepts: The Example of Smart Grids

Globally emerging smart city concepts aim to make resource production and allocation in urban areas more efficient, and thus more sustainable through new sociotechnical innovations such as smart grids, smart meters, or solar panels. While recent critiques of smart cities have focused on data security, surveillance, or the influence of corporations on urban development, especially with regard to intelligent communication technologies (ICT), issues related to the material basis of smart city technologies and the interlinked resource problems have largely been ignored in the scholarly literature and in urban planning. Such problems pertain to the provision and recovery of critical raw materials (CRM) from anthropogenic sources like scrap metal repositories, which have been intensely studied during the last few years. To address this gap in the urban planning literature, we link urban planning literatures on smart cities with literatures on CRM mining and recovery from scrap metals. We find that underestimating problems related to resource provision and recovery might lead to management and governance challenges in emerging smart cities, which also entail ethical issues. To illustrate these problems, we refer to the smart city energy domain and explore the smart city-CRM-energy nexus from the perspectives of the respective literatures. We show that CRMs are an important foundation for smart city energy applications such as energy production, energy distribution, and energy allocation. Given current trends in smart city emergence, smart city concepts may potentially foster primary extraction of CRMs, which is linked to considerable environmental and health issues. While the problems associated with primary mining have been well-explored in the literature, we also seek to shed light on the potential substitution and recovery of CRMs from anthropogenic raw material deposits as represented by installed digital smart city infrastructures. Our central finding is that the current smart city literature and contemporary urban planning do not address these issues. This leads to the paradox that smart city concepts are supporting the CRM dependencies that they should actually be seeking to overcome. Discussion on this emerging issue between academics and practitioners has nevertheless not taken place. We address these issues and make recommendations.

Sewage sludge ash recovery as valuable raw material for chemical stabilization of leachable heavy metals.

This paper proposes, for the first time, the use of sewage sludge ash (SSA), obtained by sludge combustion for the stabilization of fly ashes containing heavy metals as Pb and Zn. In particular, the proposed method aims to take advantage of valuable raw materials present in SSA, such as phosphate, silica, and alumina. The stabilization has been explained by the synergic phosphate, carbonation, and pozzolanic reactions together with the Friedel's salt formation. This method to sewage sludge management allows the complete recovery of valuable raw materials otherwise destinated for lanfill. This is virtuous example of the use of waste materials for de-pollution processes.