Dry Recycling Research Articles

Unlocking the significant worldwide potential of better waste and resource management for climate mitigation: with particular focus on the Global South.

Numbers do matter; the Intergovernmental Panel on Climate Change (IPCC)'s 2010 data that the waste sector is responsible for just 3% of global greenhouse gas (GHG) emissions has led to the misperception that solid waste management (SWM) has little to contribute to climate mitigation. Global efforts to control methane emissions and divert organic waste from landfills had already reduced direct emissions. But end-of-pipe SWM has also been evolving into more circular waste and resource management, with indirect GHG savings from the 3Rs (reduce, reuse, recycle) which IPCC accounts for elsewhere in the economy. The evidence compiled here on both direct emissions and indirect savings demonstrates with high confidence that better waste and resource management can make a significant contribution to climate mitigation, and must form a core part of every country's nationally determined contribution. Even the most advanced countries can still achieve much from the 3Rs. In the Global South, the challenge of extending waste collection to all and stopping open dumping and burning (sustainable development goal 11.6.1), essential to improve public health, can be turned into a huge opportunity. Moving early to divert waste from landfill by separation at source and collecting clean organic and dry recycling fractions, will mitigate global GHG emissions, slash ocean plastics and create decent livelihoods. But this can only happen with targeted climate, plastics and extended producer responsibility finance; and help to local communities to help themselves.

Dry Recycling of Lithium‐Containing Material by Forced Tribocharging and Electrostatic Separation

AbstractLithium‐containing components in batteries, electronics, and renewable energy pose material and waste challenges. Ongoing research focuses on eco‐friendly recycling, emphasizing electrostatic separation as a method to recover, for instance, lithium, especially in battery recycling. This study investigates forced dry triboelectric charging and electrostatic separation of powdered materials, with a focus on the charging behavior of lithium aluminate and talcum. The electrostatic separation efficiency for a blend of powders is also evaluated. Collected samples are analyzed via inductively coupled plasma‐mass spectrometry testing to assess component enrichment. Results show successful lithium enrichment from a talcum‐lithium aluminate mixture, highlighting significant separation success.

Transient and dry recycling of battery materials with negligible carbon footprint and roll-to-roll scalability

This work introduces a transient heating method for direct recycling of battery materials with outstanding efficiency, sustainability, and scalability.

Decoupling Investigation of Furnace Side and Evaporation System in a Pulverized-Coal Oxy-Fuel Combustion Boiler

A distributed parameter model was developed for an evaporation system in a 35 MW natural circulation pulverized-coal oxy-fuel combustion boiler, which was based on a computational fluid dynamic simulation and in situ operation monitoring. A mathematical model was used to consider the uneven distribution of working fluid properties and the heat load in a furnace to predict the heat flux of a water wall and the wall surface temperature corresponding to various working conditions. The results showed that the average heat flux near the burner area in the air-firing condition, the oxy-fuel combustion with dry flue gas recycling (FGR) condition, and the oxy-fuel combustion with wet flue-gas recycle condition were 168.18, 154.65, and 170.68 kW/m2 at a load of 80%. The temperature and the heat flux distributions in the air-firing and the oxy-fuel combustion with wet FGR were similar, but both were higher than those in the oxygen-enriched combustion conditions with the dry FGR under the same load. This study demonstrated that the average metal surface temperature in the front wall during the oxy-fuel combustion condition was 3.23 °C lower than that under the air-firing condition. The heat release rate from the furnace and the vaporization system should be coordinated at a low and middle load level. The superheating surfaces should be adjusted to match the rising temperature of the flue gas while shifting the operation from air to oxy-fuel combustion, where the distributed parameter analytical approach could then be applied to reveal the tendencies for these various combustion conditions. The research provided a type of guidance for the design and operation of the oxy-fuel combustion boiler.

Evaluation of essential oil isolated from dry coriander seeds and recycling of the plant waste under different storage conditions

BackgroundThis study focused on the comparison of the essential oil percentage and constituents obtained from the dry seeds and the waste of coriander plant in order to reach the best ways to store the essential oil.ResultsThe chemical composition of coriander oil was analyzed by gas chromatography–mass spectrometry (GC–MS). The analysis of coriander essential oil showed that linalool was the main constituent of dry seed oil under all conditions. It recorded 59.6, 59.28 and 47.69% of the treatments of the oil at zero time, stored in cool conditions and stored at room temperature, respectively. Concerning oil constituents of coriander waste (the remained herb after collecting seeds), the results showed that trans-anethole was the major oil constituent, followed by linalool compound. The quality of the stored oil in the refrigerator after harvest was better than the stored oil from seeds or waste under room temperature.ConclusionThe changes have been observed in the chemical composition of coriander oil extracted from seed and waste subjected to different storage conditions. The waste of coriander can be considered a new source of essential oil.

The Evaluation of the Properties of the Collision-Plate-Type Jet Mill for Dry Recycling of MOX Powder

A collision plate type jet mill is assumed to be a promising pulverizer that can control the particle size for nuclear fuel fabrication. The collision plate type jet mill consists of two modules, a classifier and a pulverizer. Coarse component of powder is cycled in the equipment and finally pulverized into objective particle size. In this report, simulated crushed powders were classified and pulverized step by step, and particle size distribution were compared. The collision plate type jet mil can produce objective size particles with less overgrinding.

Numerical simulation of oxy‐fuel combustion characteristics in a 200 MWe coal‐fired boiler

AbstractOxy‐fuel combustion in coal‐fired plants has become one of the most promising technologies for carbon capture and storage (CCS). Because of the obvious difference between the oxy‐fuel combustion medium (O2/CO2) and air in the atmosphere (O2/N2), the characteristics of combustion, heat transfer, etc., under oxy‐fuel combustion have changed greatly from those under air combustion. In this paper, computational fluid dynamics (CFD) simulation was used to investigate pulverized coal combustion in a 200 MWe tangentially fired oxy‐fuel combustion boiler. Improved models for the gas radiative properties and chemical reaction mechanisms were incorporated into the CFD code. Both conventional air‐fired and oxy‐fuel combustion were operated. Different flue gas recycling patterns (dry recycling and wet recycling) were also investigated. The temperature distribution in the furnace, the temperature field, and the CO concentration field in each scheme were analyzed, this being relevant to the design of oxy‐fuel combustion boilers. It was found that combustion could form a good tangential circle and stable temperature field in the furnace either under air‐fired or oxy‐fule combustion conditions. The temperature under oxy‐fuel combustion was lower than with air combustion. The burnout rate under the air condition was lower than that with the oxy‐fuel combustion condition. With oxy‐fuel combustion, it is necessary to pay special attention to the slagging tendency of the primary combustion zone in the furnace. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.

Neutronics feasibility of simple and dry recycling technologies for a self-sustainable breed-and-burn fast reactor

This paper is concerned with the neutronics analysis of extremely simplified recycling technologies of spent fuels in a small breed-and-burn fast reactor (B&BR). The discharged fuels of the first generation B&BR, which achieved an average burnup of 160 GWd/MTHM, were used to construct a second generation B&BR core. Two types of high proliferation resistant recycling technologies, melt refining and the newly suggested super-simplified melt and treatment, were applied to process and treat the discharged fuels. Because the burnup profile of discharged fuels varies largely depending on its position in the core, the recycling of the discharged fuels was also carried out by grouping them into recycling regions including 1, 3, and 6 recycling regions. In this study, the core performance of the 2nd generation B&BR loaded with the recycled fuel, which was produced by different recycling technologies and recycling regions, was analyzed and compared. An optimum fuel loading scheme was also adopted to maximize the performance of the 2nd generation B&BR in terms of the burnup reactivity change, core lifetime, and power profiles.

Practice‐based spillover effects: Evidence from Calgary's municipal food and yard waste recycling pilot

Analyzing the spillover effects of environmental interventions is vital for understanding how they contribute to broader societal transitions towards or away from sustainability. Past research analyzing spillover effects has produced inconsistent results, which we argue is in part due to its assumption that social life consists of rational and autonomous individuals. By contrast, we place practices as central units of inquiry, arguing that social practice theory opens up promising alternative sets of theoretical and methodological possibilities for analyzing spillover effects. Using the City of Calgary's municipal food and yard waste recycling pilot program known as the “Green Cart Pilot” (GCP) as a case study, we adopt a mixed methods approach to analyze practice‐based spillover effects (PSEs). The results suggest that the GCP had positive PSEs on dry recycling and food shopping, and negative PSEs on home composting. These PSEs could be tracked through the shared elements and geographies of mutually evolving practices, providing opportunities to respond with further interventions informed by social practice theory.Effets d'entraînement fondés sur la pratique : Preuve du programme pilote municipal de recyclage des déchets de cuisine et des résidus de jardin de CalgaryL'analyse des effets d'entraînement des interventions environnementales est essentielle pour comprendre la façon dont ils contribuent à des transitions sociales plus importantes vers ou à l'encontre de la durabilité. Les recherches antérieures analysant les effets d'entraînement ont produit des résultats contradictoires qui, faisons‐nous valoir, sont dus en partie à leur postulat d'une vie sociale formée de personnes autonomes et rationnelles. À titre de comparaison, nous plaçons les pratiques comme unités centrales de l'enquête, affirmant que la théorie de la pratique sociale dégage une série de possibilités théoriques et méthodologiques différentes et prometteuses pour l'analyse des effets d'entraînement. En utilisant le programme pilote municipal de recyclage des déchets de cuisine et des résidus de jardin de la ville de Calgary connu sous le nom de « Green Cart Pilot » comme étude de cas, nous adoptons une approche de méthodes mixtes à l'égard de l'analyse des effets d'entraînement fondés sur la pratique (EE). Les résultats suggèrent que ce programme a eu des EE positifs sur le recyclage des matériaux secs et l'achat d'aliments et des EE négatifs sur le compostage domestique. Ces EE pourraient faire l'objet d'un suivi au moyen de géographies et d'éléments partagés de pratiques mutuellement changeantes, offrant des possibilités de répondre au moyen d'autres interventions documentées par la théorie de la pratique sociale.

A Holistic Approach to Use Multi-Scale Fractions of Dry Carbon Fibre Production Waste in Filled Bulk Moulding Compounds (BMC)

The increasing demand for composites leads to a growing amount of end-of-life materialand production waste. The latter consists of a large fraction of unimpregnated fibre waste which is notsufficiently reprocessed using conventional textile processing procedures as they are either too expensiveor their mechanical performance is too low. Using pieces of dry non-crimp fabrics (patches) ina Bulk Moulding Compound process (BMC) displays a straightforward approach of fabric recycling.Adding fillers to the mixture not only offers the opportunity to modify mechanical and electrical propertiesas well as the costs but also a chance for a more holistic approach of dry fibre recycling, whenconventional fillers like chalk are replaced by ground recycled carbon fibres. In this way, all kindof dry fibre wastes can be reused in one process: Larger offcuts are chopped to smaller rectangularpatches whereas waste fractions of small offcuts are processed to carbon fibre powder as filler andprocessed together with resin to produce BMC materials. Mechanical investigations reveal that thepresented approach shows higher specific properties than the conventional filler without compromisingthe process and material quality.

The Displacement Effect of Convenience: The Case of Recycling

In light of increasingly ambitious recycling targets it is important to analyse the potential displacement effect of improving access to kerbside provision on other forms of recycling. Do households view the different modes of recycling as substitutes or complements of each other? Does this perceived relationship depend on the type of material recycled? Using data for all of the UK's local governments from 2004Q2 to 2013Q3 we analyse the nature of the relationship between the two main channels of recycling. In the case of dry recycling, the empirical findings are ambiguous on the trade­off between kerbside and non-kerbside recycling. On the one hand, the findings suggest that there is no trade-off when considering the effect of expanding kerbside provision. On the other hand, the findings also suggest that there is a trade-off when we focus on the effect of expanding non­kerbside provision. However, putting together the empirical findings with theory (in particular, the symmetry property of the Hicksian substitution effect) suggests that there is a trade-off irrespective of whether we consider expansion of kerbside or non-kerbside provision. In the case of green (compost) recycling the empirical findings on their own or together with theory unambiguously suggest that there is a trade-off.

Development of recycling processes for clean rejected MOX fuel pellets

The dry and wet recycling processes have been developed for 100% recycling of Clean Reject Oxide (CRO) generated during the fabrication of MOX fuel, as CRO contains significant amount of plutonium. Plutonium being strategic material need to be circumvented from its proliferation issues related to its storage for long period. It was difficult to recycle CRO containing higher Pu content even with multiple oxidation and reduction steps. The mechanical recycling comprising of jaw crushing and sieving has been coupled with thermal pulverization for recycling CRO with higher Pu content in dry recycling technique. In wet recycling, MicroWave Direct Denitration (MWDD) technique has been developed for 100% recycling of CRO. The powder prepared by dry and wet (MWDD) recycling techniques was characterized by XRD and BET techniques and their effects on the pellets were evaluated. (U,21%Pu)O2 pellets fabricated from virgin powder and MWDD were characterized using optical microscopy and α-autoradiography and the results obtained were compared.

Cycling of nutrients and silicon in pigeonpea and pearl millet monoculture and intercropping

In a no-tillage system, cover crops must be used that combine shoot dry matter production and nutrient recycling. The aim of this study was to evaluate shoot dry matter production, decomposition rate and macronutrient and silicon release from pigeonpea and pearl millet in monoculture and intercropping systems. A randomized block design was used with a 3 x 6 factorial arrangement, with four replications. The first factor consisted of three cover crops (pigeonpea, pearl millet and intercropping of these cover crops) and the second consisted of six sampling times [0, 18, 32, 46, 74 and 91 days after desiccation (DAD)]. Pearl millet produced greater amounts of shoot dry matter and content of N, P, K, Ca, Mg, S, C and Si and had a higher decomposition rate and macronutrient and Si release than the other cover crops. The rates of decomposition and daily nutrient release from shoot dry matter were highest in the first period of evaluation (0-18 DAD). Over time, the C/N, C/P and C/S ratios increased, while C/Si and the decomposition rate decreased. Potassium was the nutrient most quickly released to the soil, especially from pearl millet residue. Silicon had the lowest release rate, with 62, 82 and 74 % of the total content in the shoot dry matter remaining in the last evaluation of pearl millet, pigeonpea and in the intercrop system, respectively. The shoot dry matter from the intercrop system had a different decomposition rate than that from the pearl millet monoculture and pigeonpea. Plants with greater shoot dry matter production and lower C/Si ratio are more effective in a no-tillage system for providing a more complete and persistent soil cover.

Understanding the normalisation of recycling behaviour and its implications for other pro-environmental behaviours: A review of social norms and recycling

This paper examines our understanding of recycling behaviour in the context of its increasing normalisation in the UK. It reflects on the recent history of dry recycling (i.e. recycling of ‘dry’ materials such as paper, glass, plastics and cans) and asks the question as to what influence policy drivers and the increased provision of facilities for recycling have had on people's behaviour. In reviewing the evidence for recycling being considered a norm, this paper explores what influence norms, habit and identities have on recycling behaviour.It then considers what lessons the evidence offers for using the normalisation of recycling behaviour in influencing more people to recycle and to adopt other sustainable behaviours. The somewhat contentious issue of whether engaging in recycling behaviours has a positive or negative effect on people engaging with other pro-environmental behaviours is discussed. The evidence shows that both positive and negative spillover occurs and understanding where the balance lies, as well as what effect recycling being a norm plays in this, is important in determining appropriate interventions to influence pro-environmental behaviours. The paper concludes with some observations on implications of the evidence on intervention approaches to influence pro-environmental behaviours.

Release of ultrafine particles from three simulated building processes

Building activities are recognised to produce coarse particulate matter but less is known about the release of airborne ultrafine particles (UFPs; those below 100 nm in diameter). For the first time, this study has investigated the release of particles in the 5–560 nm range from three simulated building activities: the crushing of concrete cubes, the demolition of old concrete slabs, and the recycling of concrete debris. A fast response differential mobility spectrometer (Cambustion DMS50) was used to measure particle number concentrations (PNC) and size distributions (PNDs) at a sampling frequency of 10 Hz in a confined laboratory room providing controlled environment and near–steady background PNCs. The sampling point was intentionally kept close to the test samples so that the release of new UFPs during these simulated processes can be quantified. Tri–modal particle size distributions were recorded for all cases, demonstrating different peak diameters in fresh nuclei (<10 nm), nucleation (10–30 nm) and accumulation (30–300 nm) modes for individual activities. The measured background size distributions showed modal peaks at about 13 and 49 nm with average background PNCs ~1.47 × 104 cm−3. These background modal peaks shifted towards the larger sizes during the work periods (i.e. actual experiments) and the total PNCs increased between 2 and 17 times over the background PNCs for different activities. After adjusting for background concentrations, the net release of PNCs during cube crushing, slab demolition, and ‘dry’ and ‘wet’ recycling events were measured as ~0.77, 19.1, 22.7 and 1.76 (×104) cm−3, respectively. The PNDs were converted into particle mass concentrations (PMCs). While majority of new PNC release was below 100 nm (i.e. UFPs), the bulk of new PMC emissions were constituted by the particles over 100 nm; ~95, 79, 73 and 90% of total PNCs, and ~71, 92, 93 and 91% of total PMCs, for cube crushing, slab demolition, dry recycling and wet recycling, respectively. The results of this study firmly elucidate the release of UFPs and raise a need for further detailed studies and designing health and safety related exposure guidelines for laboratory workplaces and operational building sites.

Thermal oxidation behavior of WC–Co hard metal machining tool tip scraps

The thermal oxidation behavior of scraps of WC–Co hard metal machining tool tips, which have worn in high speed machining of metals or alloys, is investigated with a view toward recycling WC–Co tool tip scraps into W and Co resources. Oxidation is a preliminary process in eco-friendly dry recycling of scraps including rare metals. High oxidation rate of the WC–Co tool tip scraps is achieved when they are fragmented into many pieces to avoid the resistance to oxidation of a protective CrAlN coating. WC–Co compound scrap is oxidized to WO3 and CoWO4 with a weight gain of 20% compared to its initial weight during isothermal oxidation at 900°C. It experiences a large volume expansion of more than 200%, producing a porous microstructure. Fragmented WC–Co scraps are oxidized in a parabolic-like behavior, whereas the initial gradual oxidation of mechanically untreated WC–Co scraps is followed by a rapid oxidation after 1.5h due to the breakdown of the CrAlN coating.

Evaluation of dry solid waste recycling from municipal solid waste: case of Mashhad city, Iran

The recycling for recovery and reuse of material and energy resources undoubtedly provides a substantial alternative supply of raw materials and reduces the dependence on virgin feedstock. The main objective of this study was to assess the potential of dry municipal solid waste recycling in Mashhad city, Iran. Several questionnaires were prepared and distributed among various branches of the municipality, related organizations and people. The total amount of solid waste generated in Mashhad in 2008 was 594, 800 tons with per capita solid waste generation rate of 0.609 kg person(-1) day(-1). Environmental educational programmes via mass media and direct education of civilians were implemented to publicize the advantages and necessity of recycling. The amount of recycled dry solid waste was increased from 2.42% of total dry solid waste (2588.36 ton year(-1)) in 1999 to 7.22% (10, 165 ton year(-1)) in 2008. The most important fractions of recycled dry solid waste in Mashhad included paper and board (51.33%), stale bread (14.59%), glass (9.73%), ferrous metals (9.73%), plastic (9.73%), polyethylene terephthalate (2.62%) and non-ferrous metals (0.97%). It can be concluded that unfortunately the potential of dry solid waste recycling in Mashhad has not been considered properly and there is a great effort to be made in order to achieve the desired conditions of recycling.

Thermal radiation in oxy-fuel flames

This work investigates thermal radiation in oxy-fuel flames, based on experiments and modelling. Experiments were conducted in a 100 kW test facility in air and oxy-fuel combustion atmospheres, using two different types of fuels, lignite and propane. In-flame measurements of gas composition, temperature and total radiation intensity, were performed and used as input to radiation modelling to examine the influence of oxy-fuel conditions on gas and particle radiation characteristics. In the modelling, the spectral properties of CO 2 and H 2O are treated by means of a statistical narrow band model and particle radiation is modelled for both scattering and non-scattering particles. Experiments on the propane flame show that the flame radiation conditions are drastically influenced by the recycling conditions. With OF 27 conditions (27% oxygen in the feed gas) and dry recycling, the temperature is slightly lower compared to air-fired conditions, but the emitted intensity is significantly increased. Modelling shows that this is mainly caused by a significantly increased soot radiation. Propane flame images show that the presence of soot in oxy-fuel conditions varies strongly with recycling conditions. The contribution due to an increased emission by CO 2 is of minor importance. In the lignite experiments similar flame temperatures were kept during air and oxy-fuel combustion (OF 25 conditions with dry recycling). The measurements show that the intensity levels in both flames are similar which is due to a strong particle radiation in both environments. The modelling reveals that the dominance by particle radiation contra gas radiation is closely related to whether the particles are scattering or non-scattering.

Wide band correlated- k approaches for non-grey radiation modelling in oxy-fuel combustion with dry recycling

Increased CO 2 and H 2O concentrations in oxy-fuel combustion promote radiation compared to conventional air based technologies. Spectral radiation models are necessary to calculate the radiative properties of CO 2 and H 2O. In the present study, the wide band correlated- k method (WBCK) is evaluated for non-grey radiative transfer calculations in oxy-fuel combustion. Several WBCK formulations are presented and applied to virtual gas turbine combustors for both air and oxy-fuel combustion with dry recycling involving strongly varying H 2O/CO 2 ratios. The spectral formulation of the WBCK is the most exact approach, but leads to excessive computational times. The multiple gases formulation using three optimised absorption coefficient is found to be the optimum choice regarding accuracy and computational efficiency. The results of a standard weighted-sum-of-grey-gases method strongly deviate from those of the WBCK.

Conversion of Sulfur during Pulverized Oxy-coal Combustion

On the basis of experiments in the Chalmers 100 kWth oxy-fuel test facility, this study presents an analysis of sulfur chemistry of pulverized lignite combustion, comparing oxy-fuel and air-fired conditions. Four test cases were investigated: an air-fired case, two oxy-fuel cases with dry recycling (30 and 35 vol % O2), and one oxy-fuel case with wet recycling (43 vol % O2 on a dry basis). The amounts of sulfur in the flue-gas, ashes, and condensed water from the condenser were quantified, and a sulfur mass balance was established. The composition of the ashes and the ash-forming matter in the fuel was analyzed. The ashes were investigated by X-ray diffraction, while the size of fuel and ash particles was determined by laser diffraction. In general, the results show that the lignite has a high sulfur self-retention by ash, especially in oxy-fuel combustion. The experiments also show that the conversion of fuel S to SO2 from oxy-fuel combustion is around 35% lower compared to air-fired conditions, whereas ...