Eddy Current Separation Research Articles

Effects of particle size on the separation efficiency in a rotary-drum eddy current separator

Eddy current separation is a technology for recovering non-ferrous metals. The influence of particle size on the separation is of significant importance due to the variety of materials. It was investigated by combining simulations and physical experiments. A strong correlation between the simulation and the experiment was found by Pearson correlation analysis. Then the interaction effects between the particle size and the material type, rotational speed, magnetic pole arrangement were investigated. It shows that an optimal particle size exists for a specific condition, and the separation efficiency of fine particles can be improved by increasing rotational speed, magnetic pole number, and the electrical conductivity/density of material, as well as utilizing torque of Lorentz force. The underlying mechanism of particle size affecting separation was discovered by analyzing eddy current distribution and field gradient. These results provide insight into the design and optimization of eddy current separation for particles of various sizes. • The correlation between simulation and physical experiment was established. • There is an optimal particle size for separation under a specific condition. • The rotation of the particles increases with the decrease of the particle size. • The magnitude and distribution of eddy current is related to the particle size. • Some optimization principles of the eddy current separator were proposed.

Decoupling gaseous hydrogen production from liquid water using a magnetic‐photo‐thermal coupling reactor

AbstractTaking monolithic TiO2/nickel foam as a model photocatalytic material, we hereby report the application of magnetic‐photo‐thermal coupling field toward enhanced solar photocatalytic hydrogen production. This enhancement is attributed to the increased temperature induced by eddy current effect and effective charge separation caused by the electric field force under the alternating magnetic field condition. Particularly, we demonstrate that a proper set of the position of the monolithic catalyst relative to the reaction solution, that is, at the water‐air interface, will lead to a further enhancement of the photocatalytic activity because of the improved mass transfer property of the reactants, with a hydrogen evolution rate of 104.3 μmol h−1. Specifically, the increased temperature of the catalyst leads to the rapid evaporation of water. Hydrogen generation is thus decoupled from liquid water, avoiding kinetically disfavored bubble formation. This work provides a novel strategy to facilitate photocatalytic performance with the application of external field.

Analysis of Ambient Air PM10-Bound Pollutants Surrounding an Industrial Site and Their Prediction Using Artificial Neural Network

The 2030 Agenda dictated the Sustainable Development Goals. It states the waste reduction needs through their reuse, i.e., considering them as secondary raw materials (Objective 12.5). Bottom ashes from municipal or industrial incinerators can be reused as partial cement replacement in concrete after preventive physical processes such as ferrous metals removal (magnetic separation) and nonferrous metals removal (Eddy current separation). Net of the principal pollutant containment systems, diffusive emissions of fine particles from these processes, coupled with several screening steps and a final long-time open-air residues stabilization, could impact the surrounding environment due to the chemical composition of the particulate matter itself (inorganic and organic pollutants). Moreover, the particulate may also arise from transporting the raw bottom ashes to the pre-treatment plant (point source). The present work aims to predict the concentration of the PM10-bound organic contaminants that are usually sampled weekly (PCDD/Fs, PCBs, PAHs) from the concentration of the daily analyzed inorganic pollutants in the surrounding area of an municipal solid waste slag treatment plant, using Artificial Neural Networks (ANNs) as a forecasting tool. Moreover, ANNs have also been used as a clustering tool to evaluate the plant’s environmental impact on the surrounding area with respect to other additional emission sources.

Effects of material temperature on the separation efficiency in a rotary-drum type eddy current separator

Improving the separation efficiency of eddy current separator is of great significance in solid waste recycling. In this study, a three-dimensional transient simulation model of eddy current separator was established based on the finite element analysis. The effects of material temperature on the separation were investigated by combining simulations and separation experiments. New concepts, such as separation index and direction angle, were proposed to clarify the related mechanism. It was found that reducing the material temperature can increase the Lorentz force on conductive non-ferrous particles, so the residual temperature after cryogenic crushing can be used to improve the separation between conductive non-ferrous and non-conductive materials. Reducing the material temperature will also increase the fluctuation of the Lorentz force, which negatively affects the separation between different non-ferrous metals. The results revealed that different optimization indexes should be set for different mixtures in the design and optimization of the eddy current separator.

Smart Bin: A Much-Needed Revolution in the Garbage Management System

Abstract: A clean setting is what they want of this era. Within the name of industrialization and development, a man started destroying mother earth. As a result, garbage pickup has crossed the amount of selling. Garbage management could be a serious issue that has been increasing day- by- day. So, managing it became the priority of today’s world. As the man had understood the importance of mother earth moreover as nature. Some pretty solutions had been implying by IoT. Smart cities, smart garbage management systems, smart bins are the different ways to manage waste. This paper includes two better ways of handling waste. The robotic arm and Eddy Current separator concept are used as they are the latest of all. To make the garbage management system more effective these concepts should come in front. Human intervention will be excluded. Making it one of the powerful solutions. Saving our mother earth is the responsibility of every citizen. Though people had understood the importance of our nature and taking the necessary steps to save it. Keywords: Garbage Management System, Smart Bin, Robotic Arm, Eddy Current Separator, Municipal Solid Waste.

Eddy current separation can be used in separation of non-ferrous particles from crushed waste printed circuit boards

Waste printed circuit boards are produced greatly due to the wide application of electronic devices, in which non-ferrous metals are valuable resources. Without effective recovery processes, it can cause serious heavy metal pollution. Traditional recover technologies will cost too much energy, materials, manpower together with producing secondary ecological and environmental pollution. Eddy current separation is a green and low-cost technology to separate non-ferrous metals from others. However, it was well reported that there was a certain particle size limitation for the separated non-ferrous metals. Was it a truth or unbreakable principle for eddy current separation? In this paper, we researched the causes of the size limitation for eddy current separation. Meanwhile, the eddy current separation mechanism was detailed explained in a new comprehension related to the change of magnetic flux density, generation of eddy current force and particles’ motor behaviors. We consider that there is no size limitation for the separated non-ferrous metals in eddy current separation as long as the size of magnetic pole is enough big or small. This paper brings a new recognition about the traditional eddy current separation and will expand new application area for this environment-friendly and low-cost technology.

Green Combined Resource Recycling System for the Recycling of Waste Glass

As a major part of municipal waste, the amount of waste glass has greatly increased. Due to its stable physical and chemical properties, glass can be effectively recycled with very little loss of quality. Meanwhile, recovery of waste glass is considered to be meaningful for saving resources and energy for sustainable development. However, remanufacturing processes always need a higher level of cleaning of waste glass. Traditionally, the combination technology of hydraulic cleaning and semimanual sorting is used to clean the organic and metallic impurities of waste glass. This combination technology has the disadvantages of low efficiency and producing lots of organic wastewater, which causes heavy environmental pollution. This study proposed an environmental-friendly combined recycling system of waste glass. Waterless cleaning, iron removing, eddy current separation, and optical separation were combined to realize the cleaning and sorting of waste glass. The operation parameters of each process of this new system were discussed and optimized. This system contributed to a high-efficiency and environmental-friendly way for the recovering of waste glass in municipal wastes, and it is an engineering practice to upgrade the urban solid waste recycling technology.

Issues of induction sorting of scrap and waste of non-ferrous metals

Nowadays, one of the main economic advantages is using secondary raw materials for the production of useful materials for further use. The greatest environmental and economic effect provides the use of secondary non-ferrous metals. Eddy-current separation based on interaction force of a magnetic field with eddy currents induced by this field in conducting particles, is the most effective for the recycling of non-ferrous metals. The paper is devoted to the problem of non-ferrous metals sorting. The research results of the number of traveling magnetic field separators designs are described. The ways of improving separation efficiency are shown. Eddy-current separators can be used as stand-alone solutions, and in combination with shredder and classifying systems, in a variety of recycling plants and at metallurgical enterprises for non-ferrous metals refinement.

Optimization of Halbach magnetic roller for eddy current separation based on the response surface method and multi-objective genetic algorithm

Performance optimization of the magnetic roller of eddy current separator is an issue of great significance in the recycling industry. In this study, the Halbach array is proposed for the first time to be used in the eddy current separator. And the new concepts of area field intensity and magnet efficiency density are proposed to quantitatively evaluate the magnetic field intensity around the magnetic roller surface and the utilization efficiency of the magnet respectively. Then the effects of various structural parameters of the Halbach magnetic roller on the area field intensity and magnet efficiency density were systematically investigated by employing finite element analysis and response surface methodology. The results showed that the regression models of the area field intensity (R2=0.9846, Pred.R2=0.9420) and magnet efficiency density (R2=0.9946, Pred.R2=0.9782) are extremely significant and have good prediction capability. The magnetic roller can form a stronger magnetic field by selecting a larger magnetic block, and the utilization efficiency of the magnet is higher when the magnetic block’s shape tends to be flat or has larger curvature. Furthermore, a multi-objective optimization model with the area field intensity, magnet efficiency density, and magnetic pole number is established, and a multi-objective genetic algorithm is applied to get the optimal combinations of various structural parameters. It was found that the points of the Pareto-optimal solution are concentrated on a spatial surface, which reflects the trade-off relationship among the three objectives. It also shows that the performance parameters of many Pareto-optimal solutions are superior to that of previous studies and the eddy current separators found in the vicinity. The proposed method framework and the results are useful for the design and optimization of the magnetic roller, which will improve the separation efficiency of eddy current separation.

Incorporation of Alkali-Activated Municipal Solid Waste Incinerator Bottom Ash in Mortar and Concrete: A Critical Review.

In the light of one of the most common waste management issues in urban areas, namely the elimination of municipal solid waste (MSW; about 486 kg of the waste per capita were generated in the EU in 2017), this study discusses one technique as an outlet in the construction industry for the by-product of the waste’s incineration in energy recovery facilities (i.e., MSW incinerator bottom ash—MIBA). There have been some investigations on the use of MIBA as partial replacement of cement to be used in cementitious composites, such as concrete and mortars. However, the waste’s incorporation ratio is limited since further products of hydration may not be produced after a given replacement level and can lead to an unsustainable decline in performance. In order to maximize the incorporation of MIBA, some research studies have been conducted on the alkali activation of the waste as precursor. Thus, this study presents an extensive literature review of the most relevant investigations on the matter to understand the material’s applicability in construction. It analyses the performance of the alkali-activated MIBA as paste, mortar, and concrete from different perspectives. This literature review was made using search engines of several databases. In each database, the same search options were repeated using combinations of various representative keywords. Furthermore, several boundaries were made to find the most relevant studies for further inspection. The main findings of this review have shown that the chemical composition and reactivity of MIBA vary considerably, which may compromise performance comparison, standardization and commercialization. There are several factors that affect the performance of the material that need to be considered, e.g., type and content of precursor, alkaline activator, curing temperature and time, liquid to solid ratio, among others. MIBA-based alkali-activated materials (AAM) can be produced with a very wide range of compressive strength (0.3–160 MPa). The main factor affecting the performance of this precursor is the existence of metallic aluminum (Al), which leads to damaging expansive reactions and an increase in porosity due to hydrogen gas generation stemming from the reaction with the alkaline activator. Several approaches have been proposed to eliminate this issue. The most effective solution was found to be the removal of Al by means of eddy current electromagnetic separation.

Mathematical model and experimental investigation for eddy current separation of nonferrous metals

Comprehensive recovery for nonferrous metals from solid wastes has a significant importance for China‘s sustainable development; otherwise, it will lead to the vast loss for such values and subsequently the serious heavy metal pollution. In this investigation, a pilot-scale eddy current separator (ECS) is designed to recycle nonferrous metals from solid wastes. Firstly, a general mathematical model of eddy current force for the ECS process is established, and the important operating factors of the process are analyzed. After that, the effects of the four key operating factors, i.e., metal size, metal conductivity/density ratio, magnetic induction and feed velocity, on the ECS performance are investigated in detail using the pilot-scale ECS in separating copper and aluminum metals. Also, a mixture of Cu-Al metals is tested for separation from each other and its separation performance is evaluated. The results of separations have generally proved the mathematical model, and the ECS effectively separates the nonferrous metals, with high recovery for the metals. It is thus concluded that the ECS has provided an effective way in recycling nonferrous metals from solid wastes.

Simulation-Based Exergy and LCA Analysis of Aluminum Recycling: Linking Predictive Physical Separation and Re-melting Process Models with Specific Alloy Production

Recycling and process metallurgy are the main enablers of Circular Economy (CE). To assess the circularity of CE, a detailed understanding of the limits of the current recycling infrastructure is required. For this paper, a predictive physical separation model for Eddy Current Separator was developed using 3D particle-level detail acquired by Computed Tomography. The developed model was combined with re-melting and alloying models to create an aluminum recycling flowsheet in a simulation platform HSC Sim. Different simulation scenarios were considered, and the impact of the physical separation stage to resource efficiency was quantified by measuring the required additional resources to produce specific alloy types. The resource efficiency and environmental impacts were estimated through exergy analysis and Life Cycle Assessment based on the detailed physical and thermochemistry simulation models. The paper demonstrates how digitalization and exergy analysis allow more efficient use of resources in the sense of CE.

A new approach for the numerical analysis of an eddy current separator to recover non-ferrous metals from wastes

ABSTRACT Finite element codes are now part of the tools commonly used in the design and analysis of industrial products. The aim of this paper is to demonstrate the usefulness of the COMSOL multi-physics software for modelling the eddy current separation process (ECS) dedicated to the recovery of non-ferrous metals (Cu, Al, Pb …) from domestic and industrial waste, a technique of undeniable economic and ecological interest. This is ensured by means of a variable intense magnetic field distribution that selectively acts on materials that have different magnetisation characteristics.

Modelling of material recovery from waste incineration bottom ash

Bottom ash from municipal solid waste incineration is usually treated in order to recover valuable materials like metals and to generate a mineral material for utilisation in construction industry or disposal. At present, different technologies and combinations thereof are used for bottom ash treatment resulting in different quantities and qualities of the final products (metals and minerals). So far, a comparison of these technologies is hardly possible based on the available literature. Hence, the present paper presents and applies a modelling approach that allows predicting the quantities and qualities (in terms of composition) of the final outputs of bottom ash treatment plants. In particular, material flow analysis models of five different bottom ash treatment plants were established on goods, material and element level and the mass and composition of the output flows of these plants were calculated based on an input of 118,000 Mg/a of bottom ash dry matter. The highest recovery of metals (up to 8640 ± 820 Mg/a iron, 1530 ± 220 Mg/a aluminium, 627 ± 73 Mg/a stainless steel and 608 ± 70 Mg/a heavy non-ferrous metals) can be achieved in plants that apply comminution before any ageing processes and are equipped with jiggers, inductive sorting systems and/or a high number of eddy current separators. The iron scrap fractions separated from bottom ash are contaminated by up to 114 ± 44 mg/kg Cd and up to 9900 ± 3300 mg/kg Cu, which might impair their suitability for recycling. Only minor differences in the composition of mineral material generated by different treatment plants could be observed.

Применение линейных индукторов со встречно бегущими магнитными полями в электродинамических сепараторах

Применение линейных индукторов со встречно бегущими магнитными полями в электродинамических сепараторах

Advanced Recovery Techniques for Waste Materials from IT and Telecommunication Equipment Printed Circuit Boards

Waste from information technology (IT) and telecommunication equipment (WITTE) constitutes a significant fraction of waste from electrical and electronic equipment (WEEE). The presence of rare metals and hazardous materials (e.g., heavy metals or flame retardants) makes the necessary recycling procedures difficult and expensive. Important efforts are being made for Waste Printed Circuit Board (WPCB) recycling because, even if they only amount to 5–10% of the WITTE weight, they constitute up to 80% of the recovered value. This paper summarizes the recycling techniques applicable to WPCBs. In the first part, dismantling and mechanical recycling techniques are presented. Within the frame of electro-mechanical separation technology, the chain process of shredding, washing, and sieving, followed by one or a combination of magnetic, eddy current, corona electrostatic, triboelectrostatic, or gravity separation techniques, is presented. The chemical and electrochemical processes are of utmost importance for the fine separation of metals coming from complex equipment such as WPCBs. Thermal recycling techniques such as pyrolysis and thermal treatment are presented as complementary solutions for achieving both an extra separation stage and thermal energy. As the recycling processes of WPCBs require adequate, efficient, and ecological recycling techniques, the aim of this survey is to identify and highlight the most important ones. Due to the high economic value of the resulting raw materials relative to the WPCBs’ weight and composition, their recycling represents both a necessary environmental protection action, as well as an economic opportunity.

X-ray fluorescence sorting of non-ferrous metal fractions from municipal solid waste incineration bottom ash processing depending on particle surface properties.

A heavy non-ferrous metal fraction (< 50 mm) of municipal solid waste incineration bottom ashes from wet-mechanical treatment was separated by screening, magnetic separation and eddy-current separation into ferrous metals, non-ferrous metals and residual sub-fractions. The non-ferrous metal fractions were divided and subjected to (i) a washing process, (ii) dry abrasion and (iii) no mechanical pre-treatment to study the effect of resulting different surface properties on a subsequent X-ray fluorescence sorting into precious metals, zinc, copper, brass, stainless steel and a residual fraction. The qualities of the X-ray fluorescence output fractions were investigated by chemical analyses (precious metal fraction and the residual fraction), pyrometallurgical tests and subsequent chemical analyses of the metals and slags produced by the melting processes (zinc, copper, brass and stainless steel fraction). Screening directs brass and stainless steel primarily into the coarser fractions, while copper and residual elements were rather transferred into the finer fractions. X-ray fluorescence sorting yielded zinc, copper, brass, stainless steel and precious metals fractions in marketable qualities. Neither a negative nor a positive impact of mechanical pre-treatment on the composition of these fractions was identified. Solely the yield of the brass fraction in the grain size 16-20 mm decreased with increasing mechanical pre-treatment. The pre-treatment also had no impact on yield and quality of the products of pyrometallurgical tests.

Eddy current separation for recovering aluminium and lithium-iron phosphate components of spent lithium-iron phosphate batteries.

With the rapid development of the electric vehicle market since 2012, lithium-iron phosphate (LFP) batteries face retirement intensively. Numerous LFP batteries have been generated given their short service life. Thus, recycling spent LFP batteries is crucial. However, published information on the recovery technology of spent LFP batteries is minimal. Traditional separators and separation theories of recovering technologies were unsuitable for guiding the separation process of recovering metals from spent LFP batteries. The separation rate of the current method for recovering spent LFP batteries was rather low. Furthermore, some wastewater was produced. In this study, spent LFP batteries were dismantled into individual parts of aluminium shells, cathode slices, polymer diaphragms and anode slices. The anode pieces were scraped to separate copper foil and anode powder. The cathode pieces were thermally treated to reduce adhesion between the cathode powder and the aluminium foil. The dissociation rate of the cathode slices reached 100% after crushing when the temperature and time reached 300℃ and 120 min, respectively. Eddy current separation was performed to separate nonferrous metals (aluminium) from aluminium and LFP mixture. The optimized operation parameters for the eddy current separation were feeding speed of 1 m/s and magnetic field rotation speed of 4 m/s. The separation rate of the eddy current separation reached 100%. Mass balance of the recovered materials was conducted. Results showed that the recovery rate of spent LFP can reach 92.52%. This study established a green and full material recovery process for spent LFP batteries.

A new model of trajectory in eddy current separation for recovering spent lithium iron phosphate batteries

Eddy current separation (ECS) is an environment-friendly technology for separating nonferrous metallic particles whose size was from 2 mm to 10 mm. No wastes are generated in ECS. ECS quality of nonferrous metals from solid wastes is rather low in the production practice of spent lithium iron phosphate (LFP) batteries recovering. Repeating separation even manual sorting is required in the production. The traditional method of falling point prediction based on eddy current mechanics uses equivalent acceleration to replace separation motion curves. These curves have low precision and are unsuitable for predicting the motion trajectory of small particle size of sorted materials. In this work, eddy current separation of positive and negative plates in a crushed product of spent lithium iron phosphate battery is used as an example to establish the force and kinematics models of different materials in the eddy current separation. An iterative method, rather than average speed method, is used to improve the accuracy of the model. Displacement interval replaces disengagement angle as a separating index to improve the model’s intuitiveness and practical guidance. In the range of 2–20 mm, test results are consistent with simulation results. The copper and aluminium foils at a magnetic roller speed of 800r/min can be separated to a maximum particle size ratio of 1.72, and the maximum particle size ratio of copper and positive electrode sheets can be large. This paper provided an environmental-friendly and effective technology for separating nonferrous metals from crushed spent LFP batteries.

Combined mechanical process recycling technology for recovering copper and aluminium components of spent lithium-iron phosphate batteries

The recycling processes of spent lithium iron phosphate batteries comprise thermal, wet, and biological and mechanical treatments. Limited research has been conducted on the combined mechanical process recycling technology and such works are limited to the separation of metal and non-metal materials, which belongs to mechanical recovery. In this article the combined mechanical process recycling technology of spent lithium iron phosphate batteries and the separation of metals has been investigated. The spent lithium iron phosphate batteries monomer with the completely discharged electrolyte was subjected to perforation discharge. The shell was directly recycled and the inner core was directly separated into a positive electrode piece, dissepiment, and negative electrode piece. The dissociation rate of the positive and negative materials reached 100.0% after crushing when the temperature and time reached 300 °C and 120 min. The crushed products were collected and sequentially sieved after the low-temperature thermal treatment. Then, nonferrous metals (copper and aluminium) were separated from the crushed spent lithium iron phosphate batteries by eddy current separation with particle size -4 + 0.4. The optimised operation parameters of eddy current separation were fed at speeds of 40 r min-1, and the rotation speed of the magnetic field was 800 r min-1. The nonferrous metals of copper and aluminium were separated by the method of pneumatic separation. The optimal air speed was 0.34 m s-1 for the particle-size -1.6 + 0.4 mm and 12.85-14.23 m s-1 for the particle-size -4 + 1.6 mm. The present recycling process is eco-friendly and highly efficient and produces little waste.