MD Stephanie Zwillinger
email: stephanie.zwillinger@gmail.com

MD; PHD M Paques

MSc B Safran

MD; PHD C Baudouin

In vivo characterization of lamina cribrosa pore morphology in primary openangle glaucoma Caractérisation in vivo de la morphologie des pores de la lame criblée dans le glaucome primitif à angle ouvert

Keywords: Primary open-angle glaucoma, lamina cribrosa, adaptive optics Résumé Glaucome primitif à angle ouvert, lame criblée, optique adaptative

Purpose: To characterize the in vivo morphology of human lamina cribrosa pores in healthy and glaucoma eyes.

Patients and Methods:

In this cross-sectional, observational study, a flood-illumination adaptive optics fundus (FIAO) camera was used to perform in vivo, high-resolution, noninvasive imaging of the optic disc and lamina cribrosa in 30 patients diagnosed with primary open-angle glaucoma (POAG), in 15 healthy controls and in 14 healthy subjects with at least one direct relative with POAG. Two masked graders measured each visible lamina cribrosa pores along the major and minor axes in order to categorize pores as oval (minor/major axis ratio <0.75) or round. We used these same measurements to calculate pore surface area as a best-fit oval.

Results: Lamina cribrosa pores were visible in 95.2% of the subjects. In 52% of controls, the pores were visualized under the neuroretinal rim. In POAG patients, 78% of visible pores had an oval aspect versus 19.4% in controls (p <0.01). Average pore surface area was significantly different (1,561 px² versus 724 px²; p<0.01). In healthy subjects with at least one direct relative with POAG, 21% had pores with an aspect comparable to that of subjects in the glaucoma group.

Conclusion:

On average, lamina cribrosa pores are elongated in POAG eyes and also in healthy eyes of POAG relatives. In vivo characterization of lamina cribrosa pore morphology by FIAO imaging may enhance our understanding of glaucoma, and offer new means for its early detection.

Introduction

Primary open angle glaucoma (POAG) is a leading cause of blindness worldwide. It is a progressive optic neuropathy with structural changes in the optic disc, retinal nerve fiber layer (RNFL) and associated functional loss [START_REF] Burgoyne | The anatomy and pathophysiology of the optic nerve head in glaucoma[END_REF] . The mechanisms of glaucomatous alterations are still poorly understood, but the role played by the lamina cribrosa (LC) in the optic nerve head seems essential [START_REF] Miller | The clinical appearance of the lamina cribrosa as a function of the extent of glaucomatous optic nerve damage[END_REF] . The LC is a threedimensional porous structure composed of flexible collagenous tissue that supplies nutrition to the RNFBs via the connective tissue composed of astrocytes and a microvascular network located between the pores of the LC [START_REF] Downs | Mechanical environment of the optic nerve head in glaucoma[END_REF] . The LC is is a dynamic structure may be remodeled in response to the intraocular forces to which it is subjected [START_REF] Roberts | Changes in the biomechanical response of the optic nerve head in early experimental glaucoma[END_REF][START_REF] Strouthidis | A comparison of optic nerve head morphology viewed by spectral domain optical coherence tomography and by serial histology[END_REF] .The assumed biomechanical response is cupping and sheering, which leads to changes in the LC surface in turn modifies the morphology of LC pores [START_REF] Burgoyne | The optic nerve head as a biomechanical structure: a new paradigm for understanding the role of IOP-related stress and strain in the pathophysiology of glaucomatous optic nerve head damage[END_REF][START_REF] Roberts | Correlation between local stress and strain and lamina cribrosa connective tissue volume fraction in normal monkey eyes[END_REF][START_REF] Roberts | Remodeling of the connective tissue microarchitecture of the lamina cribrosa in early experimental glaucoma[END_REF][START_REF] Burgoyne | Premise and prediction-how optic nerve head biomechanics underlies the susceptibility and clinical behavior of the aged optic nerve head[END_REF] . Deformation of LC pores is believed by some to be at the origin of the degradation of RNFBs in that it disrupts the axonal distribution as well as oxygenation and nutritional blood flow [START_REF] Downs | Glaucomatous cupping of the lamina cribrosa: a review of the evidence for active progressive remodeling as a mechanism[END_REF][START_REF] Dai | Structural basis of glaucoma: the fortified astrocytes of the optic nerve head are the target of raised intraocular pressure[END_REF] . In glaucomatous patients the surface area and elongation of LC pores were measured in vivo using adaptive optics scanning laser ophthalmoscopy (AO-SLO) [START_REF] Vilupuru | Adaptive optics scanning laser ophthalmoscopy for in vivo imaging of lamina cribrosa[END_REF] , enhanced depth imaging optical coherence tomography (EDI-OCT) [START_REF] Park | Enhanced depth imaging detects lamina cribrosa thickness differences in normal tension glaucoma and primary open-angle glaucoma[END_REF][START_REF] Tatham | Defects of the lamina cribrosa in eyes with localized retinal nerve fiber layer loss[END_REF] , with clearly different morphological aspect between the healthy and glaucomatous LC, confirming previous studies results. 3D models of the LC have been developed to analyze its curvature and the subsequent changes in pore morphology [START_REF] Burgoyne | Three-dimensional reconstruction of normal and early glaucoma monkey optic nerve head connective tissues[END_REF][START_REF] Sredar | 3D modeling to characterize lamina cribrosa surface and pore geometries using in vivo images from normal and glaucomatous eyes[END_REF] . The morphology of the LC pores can well be analyzed with an en face technology [START_REF] Kimura | Lamina cribrosa defects and optic disc morphology in primary open angle glaucoma with high myopia[END_REF][START_REF] Shoji | Correlation between Lamina Cribrosa Tilt Angles, Myopia and Glaucoma Using OCT with a Wide Bandwidth Femtosecond Mode-Locked Laser[END_REF] . Studying the complex structure of the LC in vivo has therefore become central to glaucoma research [START_REF] Sredar | 3D modeling to characterize lamina cribrosa surface and pore geometries using in vivo images from normal and glaucomatous eyes[END_REF][START_REF] Kiumehr | In vivo evaluation of focal lamina cribrosa defects in glaucoma[END_REF][START_REF] Nadler | Repeatability of in vivo 3D lamina cribrosa microarchitecture using adaptive optics spectral domain optical coherence tomography[END_REF] .

Adaptive optics (AO) is a technology originally developed for astrophysics to improve the resolving power of ground-based telescopes. In ophthalmology, it has been used to measure and correct for the optical aberrations to provide near diffraction-limited imaging of the outer retina. It has already been successfully used in combination with OCT, SLO [START_REF] Akagi | In vivo imaging of lamina cribrosa pores by adaptive optics scanning laser ophthalmoscopy[END_REF] , and a fundus camera (flood illumination AO) [START_REF] Sarda | Topography of patchy retinal whitening during acute perfused retinal vein occlusion by optical coherence tomography and adaptive optics fundus imaging[END_REF] . AOenhanced imaging technologies has been shown to be reproducible and reliable for measuring the LC pores [START_REF] Ivers | Reproducibility of measuring lamina cribrosa pore geometry in human and nonhuman primates with in vivo adaptive optics imaging[END_REF] .

In the present study, we observed the LC using a flood-illumination AO (FIAO) camera. We sought to compare the morphology of LC pores between controls, POAG eyes and healthy subjects with at least one direct relative in the ascending line with POAG.

Patients and Methods

Cross-sectional, observational study. The subjects were either part of the consulting patient population at the Quinze-Vingts National Ophthalmic Center or members of the hospital's staff. Ethics Committee approval was received from Saint Antoine Hospital (Paris, France) as part of the iPhot project (ANR-09-TECS-009) and the study was conducted in strict accordance with the Declaration of Helsinki. Informed consent was obtained from all subjects after they received a complete explanation of this study's purposes.

Inclusion and exclusion criteria

For healthy subjects with no direct POAG relatives and healthy subjects with at least one direct relative in the ascending line with POAG, the following criteria were required: IOP <21 mmHg, best-corrected visual acuity (BCVA) of at least 20/20, FC imaging showing a clinically normal aspect of the OD, and no RNFL nor visual field (VF) deficit.

Inclusion criteria for the POAG group were IOP >22 mmHg at the time of first diagnosis, a glaucomatous appearance of the optic nerve disc (diffuse or localized rim thinning) and corresponding abnormalities observed during reliable visual field testing (considered reliable on the basis of  20% fixation loss,  15% false positives, and  33% false negatives).

Exclusion criteria for all participants were high myopia or hyperopia (±5D), ocular media opacities (including but not limited to cataract), nonglaucomatous optic neuropathy, any systemic diseases known to affect the optic nerve structure including diabetes, pituitary tumor, uncontrolled hypertension, and family relationship.

Complete ophthalmic examination

Each study participant received a comprehensive ophthalmic examination including autorefraction, BCVA measurement (Landolt chart read at a distance of 5 m), slit-lamp examination, gonioscopy, Goldmann applanation tonometry, optic disc photography, OCT of the RNFL (Carl Zeiss Meditech, Oberkochen, Germany) and standard automated perimetry (SAP) through the Humphrey Visual Field Analyzer with the 24-2 Swedish Interactive Threshold Algorithm (HFA + 24-2 SITA; Carl Zeiss Meditec, Inc., Dublin, CA). All participants provided information regarding personal or familial medical history.

Imaging with adaptive optics

Each participant consented to OD imaging in the right eye with a FIAO camera (rtx1, Imagine Eyes, Orsay, France). The rtx1 camera acquires high-resolution images using an 850-nm flashed-flood source to illuminate the region of interest (ROI) to be imaged. The device acquires images equal to 4° × 4° (1.2 mm × 1.2 mm) on the retina with a maximum lateral resolution of 2 µm. Real-time video enables fine focusing, then a series (stack) of images is acquired during 4 s. Examinations were conducted in a dark room in order to facilitate imaging without pharmacological pupil dilation. An external target guiding the left eye was used to orientate the eye in order to observe the right optic disc.

We used Image J (National Eye Institute, Bethesda, MD, USA) to delineate and analyze the images using the pixel (px) as the unit of measurement. To determine the morphological characteristic of each pore, each grader manually drew the major and minor axes of each visible pore. The pore was considered circular if the ratio of minor over major axis was > 0.75 or oval if below. To calculate the surface area of LC pores, the measurements of all pores that passed the validation test in the preceding step were used to determine the size of the best-fit oval (BFO) (figure1).

The images were independently reviewed by two graders who were masked from all other subject information. Pore measurements were excluded if the graders did not reach consensus on both axes as defined by a set difference of ±15%.

Statistical analysis

To compare results, we used the Student's t test for quantitative variables and Fisher's exact test for nominal qualitative variables. We chose a critical cutoff value for the percentage of oval pores among the LC pores visible with AO-FC. The sensitivity and specificity versus cutoff graph was created using a sensitivity and specificity report. The Kappa coefficient was calculated to verify interobserver variations.

All statistical analyses were conducted with commercially available software (StatView® 24 ) and the type 1 error level was set at 0.05.

Results

Study population

59 subjects gave their consent to be investigated, comprising 15 healthy control subjects, with no direct relative in the ascending line with glaucomatous neuropathy (group 1), 30 POAG patients (group 2) and 14 healthy subjects with no familial relation with the other groups and who had at least one direct relative in the ascending line with glaucomatous neuropathy (group 3) (Table 1). All POAG patients were followed regularly prior to the study for at least 2 years and their IOP was measured under 21 mmHg with medical treatment at each follow-up visit.

Morphological study of the OD and LC in controls (group 1)

In all but two cases, LC imaging enabled more precise visualization of the LC when compared to images obtained with a FC. In these two cases, the LC was not visible, presumably because of RNFBs thickness. Most of the pores observed were circular in shape (Fig. 2). The minimum number of observable pores was 3 and the maximum was 27. The minimum surface area was a BFO of 50 px², the largest was 2,994 px², and the average was 724 px² (Table 1). In this group, 19.4% of LC pores were to be oval and one subject had no oval-shaped pores at all. There was excellent agreement between graders as to whether an eye had an oval-shaped pore (kappa=0.8; 95% CI, 0.64-0.95). One optic disc was excluded because of the difficulties visualizing the pore limits, resulting in a significant difference in its measurements by the two graders.

Morphological study of the OD and LC in POAG subjects (group 2) Thirty eyes were examined. There was no significant difference in age (p=0.062) and gender (p=0.75) between POAG subjects and healthy controls. Mean age was 54.3 years (±12.5 years) and 57% were female (Table 1). The LC was visible by FIAO imaging in all eyes. Most of the pores were enlarged, elongated and fused (Fig. 3). We also noted an apparent torsion of pores close to the scleral rim. In one subject with advanced POAG, the pores had almost completely disappeared. The minimum number of measurable pores was 9 and the maximum was 41. The minimum surface area was a BFO of 36 px², the maximum was 13,558 px², and the average was 1,561 px². In this group, 78% of LC pores were oval (kappa=0.8; 95% CI, 0.64-0.95). The average surface area of LC pores was notably greater in group 2 than in group 1 (Table 1) in POAG subjects versus healthy controls (1,561 px² and 724 px², respectively, P<0.0028). In POAG subjects, 78% of pores were oval versus 19.4% in healthy controls (p<1. 5 10 -7 ). The cutoff value of 60% maximized sensitivity (100%) and specificity (79%) (CI=95%).

Morphological study of the LC in group 3

Fourteen eyes were examined. Their age was significantly lower than in the other two groups. This significant difference prevented us from conducting a valid statistical analysis between these three groups. Of the 14 subjects in this group, three had LC pores with an aspect comparable to that of subjects in the POAG group, as more than 60% of pores were oval and the average surface area of those pores was 1,196 px² (Fig. 4). Two had LC with no visible pores. Nine subjects in this group displayed an aspect of the LC comparable with that in healthy controls. The average surface area of those pores was 637 px² and less than 60% of pores were oval, although all nine had some oval LC pores (kappa=0.8; 95% CI, 0.64-0.95).

Discussion

Interest in LC pore study is gaining momentum, because it is assumed to be the primary location of retinal nerve fiber glaucomatous damage. FIAO imaging is a promising technique for analyzing LC pores.

Previous in vivo studies [START_REF] Miller | The clinical appearance of the lamina cribrosa as a function of the extent of glaucomatous optic nerve damage[END_REF][START_REF] Akagi | In vivo imaging of lamina cribrosa pores by adaptive optics scanning laser ophthalmoscopy[END_REF] and more recently studies using three dimensional characterization of the LC, have shown that pores in POAG eyes subjects tend to be larger and elongated [START_REF] Nadler | In vivo three-dimensional characterization of the healthy human lamina cribrosa with adaptive optics spectral-domain optical coherence tomography[END_REF] . Analyses of LC pore dynamics in POAG have suggested that they rotate near the scleral opening, where compression forces are strongest, thus leading to the fusion of peripheral pores [START_REF] Bellezza | Deformation of the lamina cribrosa and anterior scleral canal wall in early experimental glaucoma[END_REF] .

It

has not yet been confirmed if the changes in pore morphology in POAG eyes is a cause or a consequence of the disease. However, recent studies have advanced the idea that some LCs may have structural weakness [START_REF] Ma | Progress in understanding the association between high myopia and primary open-angle glaucoma[END_REF][START_REF] Jung | Factors affecting plastic lamina cribrosa displacement in glaucoma patients[END_REF][START_REF] Kang | Sectoral variations in the distribution of axonal cytoskeleton proteins in the human optic nerve head[END_REF] . In these cases, axonal degradation may be caused by the loss of their support inside the LC, for instance insufficient nutrition from the microvascular network and/or the loss of contact with astrocytes [START_REF] Balaratnasingam | Comparative quantitative study of astrocytes and capillary distribution in optic nerve laminar regions[END_REF] .

All of the aforementioned studies point to the fact that LC pores in glaucomatous subjects becomes larger and elongated. We obtained similar results in this study. Concerning the examination of subjects with at least one direct relative in the ascending line with POAG, it could corroborate an inherited weakness of the LC [START_REF] Liu | Family-based analysis identified CD2 as a susceptibility gene for primary open angle glaucoma in Chinese Han population[END_REF][START_REF] Huang | Collagen: a potential factor involved in the pathogenesis of glaucoma[END_REF][START_REF] Dong | Bibliometric network analysis of glaucoma[END_REF] . This technique has several limitations. The FIAO imaging field is limited and therefore requires acquisition of multiple images in order to visualize more than the pores of the LC. Pores may have been missed because of poor visibility of the LC, especially in healthy eyes, 13% of which were excluded. The LC is a three dimensional structure. Posterior cupping may have changed the angle of incidence between the laminar surface and the imaging axis, hence inducing errors in measurements in pore dimensions [START_REF] Sredar | 3D modeling to characterize lamina cribrosa surface and pore geometries using in vivo images from normal and glaucomatous eyes[END_REF][START_REF] Shoji | Correlation between Lamina Cribrosa Tilt Angles, Myopia and Glaucoma Using OCT with a Wide Bandwidth Femtosecond Mode-Locked Laser[END_REF] .

In order to understand the morphological modifications to the LC that are specific to glaucomatous neuropathy, it is essential to clearly characterize the difference between healthy and pathological LCs and define a morphological characteristic that would better correspond to a glaucomatous LC pore pattern. The FIAO cmarea used in this study enabled us to clearly measure a difference between two types of pores -round and oval -that is coherent with other in vivo observations. The proportion of LC pores considered to be oval using our method allowed us to determine a cutoff value based on the percentage of oval pores among the visible pores. The examination of subjects with at least one direct relative in the ascending line with familial history of POAG (group 3) allowed us to test our hypothesis and to propose responses regarding the origins of the LC pore shape. We found that three out of these subjects had more than 60% oval-shaped pores. The youngest of those subjects was 9 years of age. In the nine remaining subjects, less than 60% of LC pores were considered oval. In the first three cases, these early alterations of the LC pores were detected before the suspected changes that would affect the RNFLs. A closer follow-up routine with repeated IOP measurements will be proposed to these subjects to detect whether any signs of glaucomatous neuropathy develop further.

Thanks to this technique and our findings in descendants of POAG patients, the respective roles of IOP and LC morphological changes, thus in POAG pathogenesis, could be clarified by a further prospective study. The percentage of oval LC pores may thus be a warning signal requiring closer and more regular medical examination. However, only a long-term prospective study with a larger population would be able to confirm whether this morphological aspect is truly an early sign of impending glaucomatous neuropathy, a risk factor -whether or not it results in further IOP elevation during the subject's lifetime -or only coincidence. This morphological pattern could translate into a genetic phenotype to identify subjects who have inherited one or several risk factors for POAG.

Figure 1 :

 1 Figure 1 : Measurement procedure of lamina cribrosa (LC) pores. Left, the optic disc as seen with FIAO imaging; right, morphometric analysis.

Figure 2 :

 2 Figure 2: FIAO images of the LC in two healthy control subjects.

Figure 3 :

 3 Figure 3: Example of FIAO imaging of the LC of two POAG subjects.

Figure 4 :

 4 Figure 4: Example of FIAO imaging of the LC of two healthy subjects with at least one direct relative in the ascending line with POAG.

Michel Paques is a consultant for Imagine Eyes.


N Menad
email: n.menad@brgm.fr.

A Seron

CHARACTERISATION OF PERMANENT MAGNETSFROM WEEE

Keywords: Waste of electric and electronic equipments, magnets, thermal treatment, characterization

The increasing use of rare earths elements in a number of recent technological innovations led to a rapid increase in (plus 50% in the last decade) of their applications. Europe is one of the most important regions of consumption of these substances. In this context, Europe in its 'Raw materials' strategy puts the recycling at the center of its concerns to provide a part of securing its supplies in rare earth elements. Recycling of these substances, on an industrial scale, remains somewhat developed while it presents numerous advantages over the exploitation of primary resources. This paper will present some results obtained from characterization study of permanent magnets present in wastes of electric and electronic equipment. Three different electronic components containing magnets are identified: hard dick drives, small electric motors and speakers. Several kilograms of theses wastes have been sampled at recycling plant. The representative sample has been dismantled manually to recover the magnets contained to quantify the amount of magnets in the investigated components. Thorough characterization results show that the weight percentage of magnets varies in the three investigated electronic components: 4 6% in the speakers, 2.5-2.8% in the hard disks, and between 0.8 and 2% in some electric motors.

The results of the thermal treatments of the magnets of the investigated samples show that the majority of these magnets lose their magnetic property upon reaching Curie temperature (300-400° C) in 15-20 minutes.

Scanning Electronic Microscopy (SEM) reveals the morphological aspects of these magnets which consist in crystals shaped tetrahedral phase Nd 2 Fe 14 B sintered in the presence of the interphase rich in rare earths elements (Nd, Dy and Pr). The magnetsare layer coated with 20 µm thick. This layer consists in Ni, Zn or metals alloys. The chemical composition of some magnets obtained from EDS is close to theoretical composition of the standard magnet.

INTRODUCTION

The increasing use of rare earths elements (REEs) in a number of recent technological innovations led to a rapid increase in (more than 50% in the last decade) their applications. In this context, Europe in its 'Raw materials' strategy puts the recycling at the center of its concerns to provide a part of securing its supplies ofREEs. Recycling of these substances, at the industrial scale, remains somewhat developed while it presents numerous advantages over the exploitation of primary resources:

 Europe is one of the most important regions of consumption of these substances. It has, in addition, accumulated during decades of consumer goods that arrived at end of life and are considered as secondary resources which could be extracted from the REEs  French and European dependency on resources from foreign countries can be reduced through the recycling of post-consumer waste;  Treatment of secondary resources for the production of REEs would not cause no health and no environmental risks induced linked to the presence of processions of radionuclides from primary deposits;  Production of metal resources through the use of secondary resources is most often done with energy consumption much lower than those observed for the exploitation of primary resources. It also expects that most recycling operations have an environmental benefit.

Thus, in order to increase the efficiency of the use of the REEs and decrease European dependence on these strategic elements, an effort to research and development should be made in all areas of their life cycle whether it is exploitation of ores (mineral processing, extractive metallurgy) or from the equipment at the end of life as the waste of electrical and electronic equipment WEEE.

This paper presents the work done with the project financed by French research agency in the frame of the contract ECO-TS deals with characterisation of permanent magnets present in electronic devices in order to recovery REES contained.

RARE EARTH ELEMENTS

The rare earths market is private, reserved only for professionals and depends on supply and demand. These rare earths have no stock or State regulations instruments such as gold and oil market. Their prices are reported by the main world mines, representing the main stakeholders of rare earths in this case Chinese mines that monopolize the market. The rare earths are sold in different forms (oxide or metal) with 99% purity.

Application of REEs

In General, rare earths elements (REEs) are used in high technology, especially in the manufacture of high performance magnets, in phosphors present in color televisions or energy saving lamps, catalytic converters, batteries for mobile phones and magnetic alloys. REEs are also used in medical applications (medicines, ophthalmology, NMR, IRM, etc...). Table 1groups their applications. It can be noted that the applications which consume more than 25% of REEs, are considered as major applications as shown in red color in table 1. As examples, we can say Samarium, neodymium, praseodymium, Gadolinium and Dysprosium which are the most used in the manufacture of permanent magnets Table 1: Global applications of rare earth elements (Roskill) Neodymium is one of the most abundant elements in WEEE. As shown in Figure 1, it is present in high quantity in different electronic devices. (Loudspeakers, HDD, LCDs, Tablet computers etc…).

As shown by Figure 1, the magnets can be found in different electronic devices with different concentrations of Neodymium (Nd). For example: computer contains in average 5.03 mg Nd: 2.4mg in HDD, 771 mg in CD-ROM and 310 mg in Loudspeakers; Laptop

Magnets in WEEE

Since the development of powerful magnets (Nd-Fe-B) in 1980, the volume production of Neodymium has increased dramatically. This development permitted to improve significantly the performance of small engines and reduce the bulk and weight of portable electronic devices. As example, utilisation of miniaturized engines in mobile phones on the basis of small Nd-Fe-B type magnetsfor their vibration functions. These magnets are also very widely used in the computer HDD where they constitute the engine, which ensures the positioning of the read/write heads. They allow to improving significantly the performance of this storage device and contributing to the reduction of the computer size. If the increase in the prices of rare earths elements has been relatively constant over the last decade, the technological revolution of developed countries made appear of the deficits of supply and the tensions that have resulted in a surge in prices since January 2010.

Despite the fact that the hard disk for computer market is doomed to continue its regression by 2017 (Figure 2), in general, the opportunities have been identified for hard disk drives. According to the literature, an overall increase of 11% by 2016 is expected on the market of hard disks (Figure 3).

Production and market of magnet

China is a larger producer of magnet in the world. In 2010, China and Japan produce about 50 Gg (50 000 t) and more than 10 Gg (10 000 t) of NdFeB type magnet respectively (Figure 4,A). However, the production of magnet in Europe and USA is lower than 14 000 t and 2 000 t respectively (Figure 4,B). In 2012, the global demand of REEs for the manufacturing of permanent magnets is estimated around 25 500 t, approximately 21% of the worldwide demand which is about 120, 000t (Roskill, 2012). The demand for the magnets is very rapid increases (>150%) from 2000 to 2007 before decreasing to about 1/3 during the financial crisis between 2008 and 2009. The permanent magnets represent a very important market for REEs with a rapid increase in 2014. About 27Ktons of rare earth oxides (REOs) have been consumed for the production of magnets representing 22% of total consumption.

As shown in light blue bar in the charts (Figure 5) the sales of neodymium-iron-boron (Neo) magnets are increasing exponentially. Sales of all permanent magnets were about $8 billion in 2005 and NeO alone will be sold over $17 billion in 2020 [START_REF] Benecki | Permanent Magnets: 2010 -2020 ,author 6 Sofred Consultants, Enjeux économiques des métaux stratégiques pour les filières automobiles et aéronautique[END_REF] Figure 5: Market of Permanent Magnets [START_REF] Benecki | Permanent Magnets: 2010 -2020 ,author 6 Sofred Consultants, Enjeux économiques des métaux stratégiques pour les filières automobiles et aéronautique[END_REF] The NdFeB type magnets are the most commercialized in 2015. China is the country that consumes most REOs for magnet manufacturing. According to Roskill (2012), the global application of NdFeB magnets is expected to increase on average about 9% per year by 2020: 6-8% per year by 2016 with an acceleration from 2016 (Sofred Consultants, 2013) . Demand will be driven by three sectors:

1. ICT: hard drives, mobile phone, DVD, etc. that contain low amounts of NdFeB magnets but are produced by mass (14000t of magnets would have sold in 2012) 2. Electric motors (between 60 g and 350 g of NdFeB magnets by engine) in Asia primarily and hybrid and electric cars (approximately 2 kg of magnets per vehicle); 3. Wind turbines: current wind turbines use close to 600 kg of magnets per MW (direct drive), which corresponds to 155 Kg of neodymium and praseodymium Kg 27.5 per megawatt. The new generation of wind turbines will require much less reported power (165-250 kg of magnet/MW). However, the power of wind turbines to increase the size of the magnets will continue to grow and consequently the demand for rare earths. Some authors announce the figures of 2.3 tons of neodymium and 400 Kg of praseodymium by wind for 10 to 15 MW of power [report notes strategic CEIS, Matthieu Ahmed 2014].

The majority of the rare earth type magnet is manufactured in China (80%), 17% in the Japan and 3% in Europe. According to S. Contantinides, 2012, the change in the use of the magnet predicts a necessary increase of dysprosium by 80% between 2010 and 2015, while the requirement for neodymium will increase much less to approximately 54%.

3. MATERIAL AND METHOD Three samples of hard disks drive (HDD), electric motors and loudspeakers were characterised in this work. More attention is given toHDD. After collection, the electronic devices containing magnets were subjected to sampling shown in figure6. The working of specimen samples that can be defined as samples made without special precautions for HDD, the loudspeakers and electronic motors in the small electronic appliances were collected from various industrial plants. The characterisation of these specimens allowed us to define the minimum masses to be taken to ensure the representativeness of the samples and analyses. As noted, the magnets in these electronic products are very heterogeneous. One tonne of each product containing these magnets is required to perform the tests at the laboratory and pilot scales.

Dismantling and magnet recovery

The representative samples of electronic components collected from industrial plant were sampled again for characterisation. As shown by figure 7, the bag containing laptop HDD contains about 70% of Laptop HDD and 30% computer HDD. However, the bag containing computer HDD consists of 98% of computer HDD and 2% others non-identified components. HDD were dismantled manually to recover the contained magnets. These magnets are then heated to 300 ° C between 15 and 20 minutes to demagnetize them. Each HDD is referenced by brand name, the year and the memory content volume. The samples are dismantled manually and all parts are weighted and the weight percent of the magnets contained each HDD is calculated. Furthermore, the recovered permanent magnets are characterised by Scanning Electron Microscopy (SEM) and chemical analyses A hundreds of loudspeakers and a few tens of small electric motors were collected from representative professional equipment (Figure 8). The characterization procedure performed is the same as that used for HDD.

HDD/Laptop computer

Weight (kg) Wt%

Figure 8: Recovery of magnet from different electronic components of WEEE by manual dismantling

The results obtained from characterisation of computer HDD show that magnet represents about 3 Wt%, aluminium 80 Wt%, PCB 7 Wt%, plastics 1 Wt%, iron 8 Wt% and 1Wt% others (ceramics etc…) see Figure 9.

Figure 9: Composition of HDD

After dismantling of components containing rare earth type permanent magnets, the total fraction of electronic components containing permanent magnets was determined by weighing of all components and the only magnets was taking into a count for the determination of an average concentration magnet in each type of components. The results are presented in Figure 10. It can be seen, for central unit, the Wt% of magnet is varied from 1 Wt% to 6Wt% in average 3Wt%. However, for laptop, the Wt% of magnet is varied from 1 to 4Wt% in average 2.5 Wt%. Table 2 gives the weight percentages of magnets contained in other electronic components such as loudspeakers (4 -6 Wt%) and electric motors (22 -26 Wt% or 0.8 -2 Wt%). To determine the temperature which the magnet loses its magnetic properties, the test of TG/DTA was carried out on the permanent magnet recovered from electronic devices. The results are shown inFigure 11. This figure shows the thermal behaviour of permanent magnets of HDD and loudspeakers in the temperature range of 50 to 500°C. It can be seen that the effect for loudspeakers permanent magnet is at 459°C, this can be attributed to the Curie temperature of ferrite magnets. However, for HDD, two effects are observed. The first one is started at 145°C, which is attributed to their temperature utilisation, and the second one at 297°C. This temperature is attributed to the Curie temperature of the rare earth type magnets at which they lose their magnetic properties.Then, to demagnetize the NdFeB and ferrites type magnets, it must be heated, respectively, at the temperatures around 300°Cand 500°C. The collected samples of loudspeakers and electronic motors are heterogeneous in point of view of type of magnet contained. To select those interested samples, X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) were carried. Figure 12 shows the XRD patterns of loudspeakers and electric motors. From this figure, it can be seen that not all permanent magnets present in the collected samples of electronic devices contain NdFeB type magnet. Figure 13 shows that the Ni or Zn protective coating of magnet consists of a layer of approximately 20 µm thick. The morphology aspect of the same magnet observed from a polished section that lets appear the small size of grain. Some of them are filled with a mixture of rare earths and other almost nonexistent because of a sintering performance(Figure 14).The analysis conducted by EDS (Energy Dispersive Spectroscopy) on the magnet constituents is similar to that obtained theoretically by calculation from the formula Nd 2 Fe 14 B (Table 3)The analysis preformed on tetrahedral grains confirms their composition of Fe, Nd and Pr and the composition of interphase which is rich in rare earth (Nd, Pr, Dy). Identification of deposits of the magnets present in WEEE, and focusing on hard drives, small electric motors and speakers, we take into account 98% of the magnet field receivable in the small electronic appliances feed. The rest of the present magnets in this stream is disseminated in other equipment such as phones fixed, mobile, internet box... more difficult recoverable. 2. Two sampling campaigns were conducted on two different sites of industrial plant to collect a representative sample of hard drives and the loudspeakers. 3. The characterization study shows that the weight percent of magnets varies in the three investigated targets: 4 -6% in the loudspeakers, 2.5 -2.8% in the hard disks of station unit of computers, 2 -3% in the laptops, and between 0.8 and 2% in small electric motors. 4. Scanning electron microscopy (SEM) shows that the magnets containing rare earth elements present in WEEE consist of Nd-Fe-B alloy in a tetrahedral form with an interface rich in REEs (Nd, Dy and Pr). About 20 µm thick coating layer consists of Ni, Zn or an alloy of Cu / Ni. 5. According to the XRD, the permanent magnets present in WEEE contain not only REEs, but also ferrites. 6. The Curie point at which the magnets lose their magnetic properties was determined by TGA for different investigated samples of magnets. The results show that the temperature utilisation of NdFeB type magnet is around 150°C and Curie point is about 300°C. However the ferrite magnet loses its magnet property at about 500°C.

  (4.45 mg Nd):1121 mg in HDD, 621 mg in CD-ROM and 626 mg in Loudspeakers; Tablet computer (347 mg Nd); Mobile-phone (46.4 mg Nd); Smartphone (120 mg Nd); Earphones (260 mg Nd) and LCD ( 3650 mg Nd).

Figure 1 :

 1 Figure 1: Neodymium in electronic devices (Luise Westphal and Kerstin Kuchta)

Figure 2 :Figure 3 :

 23 Figure 2: Worldwide supply of Desktop and portable PCs, Portable PCs and Tablets forecast 2017

Figure 4 :

 4 Figure 4: Production of NdFeB magnet in China and Japan (A), USA and Europe (B) (Xiaoyue Du and T.E. Graedel)

Figure 6 -

 6 Figure 6 -Sampling of Hard disks at French Plant recycling company

Figure 7 :

 7 Figure 7: Hard Disks drive representative sample Two samples from hard drives of computers and laptop (Figure x) representing about 500HDD were dismantled manually to recover the contained magnets. These magnets are then heated to 300 ° C between 15 and 20 minutes to demagnetize them. Each HDD is referenced by brand name, the year and the memory content volume. The samples are dismantled manually and all parts are weighted and the weight percent of the magnets contained each HDD is calculated. Furthermore, the recovered permanent magnets are characterised by Scanning Electron Microscopy (SEM) and chemical analyses A hundreds of loudspeakers and a few tens of small electric motors were collected from representative professional equipment (Figure8). The characterization procedure performed is the same as that used for HDD.

Figure 10 -

 10 Figure 10 -Weight percent of magnets in computers (central units and laptops)

Figure 11 :

 11 Figure 11: TGA of permanent magnets of HDD and loudspeakers.

Figure 12 :

 12 Figure 12: XRD patterns of loudspeaker and small electric motor magnets

Figure 13 :

 13 Figure 13: Photo SE of magnet coating Figure 14: Morphological aspects and EDS of HDD magnet

Figure 15 :

 15 Figure 15: Textural and chemical Characterization of a HDD permanent magnet after demagnetization The permanent magnets that we are looking for contained Nd-Fe-B doped with Dy and Pr, and the chemical composition is shown in table 3.

Table 2 :

 2 Weight percent of magnet in different electronic components 4.2. Determination of demagnetisationtemperature

Table 3 -

 3 Chemical composition of magnet from computer hard disks, %

	5. CONCLUSIONS
	1.

ACKNOWLEDGMENTS

This work presented herein was performed in the frame of contract N° ANR-13-ECOTS-0006-01The authors gratefully acknowledge the financial support of the French National Research Agency which has made this collaboration possible, Team2 and other partners of the research project for samples and discussions: Galloo, GPM Rouen, Eco-systèmes, Selfrag and Cyclamen. The authors also thank the reviewers for their constructive comments.


N Menad
email: n.menad@brgm.fr.

A Seron

M Save

Y Menard

N Maat

V Jean-Marie Le Breton

V Nachbaur

A Bizouard

M Delain

L Waignein

R Hennion

O François

F Von Der Weid

RECOVERY OF PERMANENT MAGNETS TYPE NDFEB FROM WEEE

Keywords: equipment, permanent magnets, rare earth elements, thermal treatment, recovery, vaporization process

The increasing use of rare earths elements (REE) in a number of recent technological innovations led to a rapid increase (plus 50% in lastdecade) of their applications. Besides, Europe is one of the most important regions of consumption of these substances. In this context, in its 'Raw materials' strategy, Europe puts the recycling at the center of its concerns to secure its supplies in REEs. Recycling of these substances, on an industrial scale, remains somewhat developed while it presents numerous advantages over the exploitation of primary resources.

Thus, in order to increase the efficiency of the use of the REEs and to decrease European dependence on these strategic elements, research and development efforts must be achieved in all areas of their life cycle whether it concerns exploitation of ores or end-of-life equipment such as the one EXTRADE project targets (Wastes of Electric and Electronic Equipment).

In this context, the project EXTRADE aims to develop new fields of valorization of permanent magnets type NdFeB present in WEEE targeting 3 types of electronic equipment,i) hard disk drives of computers, ii) speakers of audio and video devices and iii) small electric motors present in ICT (information and Communication Technologies).

EXTRADE project proposes to address the extraction of the NdFeB permanent magnetsfrom the WEEE deposit, developing units operation of treatment of WEEE intended to retrieve the contents of the magnet type NdFeB and to develop thermal, physical and physico-chemical treatments for producing new magnets or fractions enriched in alloys of REEs compatible with a recycling in the hydrometallurgical production of REE.

INTRODUCTION

The developed countries face a persistent concern about the supply of criticalmetals. Thesemetals, including REEs, are essential to the development of innovative high-tech industries, and particularly those associated with green energy. The recent political crisis caused by China towards Japan putting REEs supply in balance (95% of the world's needs) amplified those concerns. The fundamental issue is to ensure the supply of industries manufacturing for which these chemical compounds made from criticalmetals and alloys are essential, even though their availability shows vulnerabilities at different levels of their supply chain. In this context, the European Union released its report 'Critical raw materials for the EU' that identifies 20 metals described as strategic for the European economy as a whole. At the French level, the roadmap to improve the productivity of resources is marked by the implementation of the Plan of strategic metals and the creation of the COMES(Committee for strategic metals). Among these strategic metals, rare earths contained in permanent magnets of certain WEEE categories are a priority target of growing interest. Since the development of powerful magnets made of neodymium (Nd-Fe-B) in 1980, the volume production of this material has increased dramatically.

The new technologies that use more rare earth elements (REEs) contribute to growing and sustainable demand, at the time, of these substances. Europe is one of the most important regions of REEs consumption through its industries with high added values. She has also accumulated during decades the consumer"s goods that arrived at end of life, and are considered as secondary resources from which REEs can be extracted. The development of a specific sector to recover these permanent magnets contained in the WEEE and recycle rare earths elements contained must therefore become a priority.

The main objective of this work is the implementation of effective techniques oftreatment, recycling and valorization of permanent magnets present in the WEEE.

In Japan, the recycling of REEs from permanent magnets is well developed.It is directed primarily by extractive metallurgy. This problem is relatively recent in Europe. At the scale of the French territory no specific treatment was developed to the point. At present, the current reflections focus on recycling magnets in wind turbines and hybrid or all-electric vehicles as they are the higher magnets -consuming sectors, yet the WEEE have to be considered too as the amount of REEs in the WEEE flow is not negligible.

However, the recycling of permanent magnets containing REEs in WEEE is facing many locks. As an example, we can list:

1. the heterogeneity of the WEEE deposit and the difficulty of obtaining representative samples, 2. the dispersion of rare-earth in WEEE deposit, 3. lack of knowledge of rare earths content in small household appliances + IC flow, 4. the magnetic property sought in permanent magnets constitutes a technical lock during recycling operations (these magnets ' stick' in grinding/sorting equipment), 5. the variability of the flow of WEEE (ungraded) input method, 6. the effectiveness of the unit operations of crushing and sorting, comminution/liberation of complex waste matrices,

1.1.

Rare earth elements Rare earths elements are a group of that exhibits special properties (magnetic, electronic, catalytic and optical)and which comprisesyttrium, scandium and the 15 lanthanides.

Unlikewhat is suggested by their name, these metals are quite prevalent in the earth's crust, to the equal of some base metals. Generally they are used in small proportions but their application for mass-market products makes that the world demand quickly increases.It is important to note that all REEs are included in the European list of strategic metals. Worldwide, their demand is slightly higher than their supply (Figure 1). This is true for Eu, Dy, Tband Y and not for Nd and Ce. The total demand of REEs for different applications is estimated about 162 500 t representing 66% of market share (Table 1). For permanent magnets (not only in WEEE), the total demand is around 36 000 t representing 22% of market share. Europe has classified all REEs within 20 critical metals and according to US-TMR, the REEs such as Nd, Dy, Eu, Y and Tb will continue to be critical in 5 to 15 years see figure 2. Application of REEs The majority of REEs are used in high technology, especially in the manufacture of high performance magnets, in phosphors present in color televisions or energy saving lamps, catalytic converters, batteries for mobile phones and magnetic alloys. REEs are also used in medical applications (medicines, ophthalmology, NMR, IRM, etc...).

End

As shown by figure 3, 81% of rare earth elements are produced in China, 13% in Japan and north east of Asia, 2% in USA, and 4% in the rest of world including Europe. These REEs are used in permanent magnets (22%), as alloys (19%), as catalysts (21%), in glass industry (10%), in polishing (16%), in ceramics (5%) and in phosphorous (7%). Extrade process [2] The extraction of REEs from permanent magnets is well documented in the literature. There is a large enough set of publications and patents regarding the extraction of rare earth from permanent magnetsscraps, and their recycling.However, there are few studies regarding the recyclingof the magnets from the small household appliances "stream. The only studies so far are mostly Japanese, with the development of a machine to separate and collect NdFeB type magnets from hard disks drives and compressors. This new machine can process up to 100 HDD per hour.

The Extrade process shown in Figure 4 is focusing on the improvement of the classical treatment process of WEEE. After depollution of WEEE, the components containing magnets would beisolated,thermally treated to demagnetize them and fragmentedto release the magnets, then sorted regarding there technologies (in order to isolated theNdFeB magnets),.

The magnets would berecovered by a separator X, and after cleaning, the recovered magnets would bemicronized. The powders obtained would bepurified for the production of new magnets or for the extraction of the rare earths contained.

MATERIALS AND METHODS

Materials

The EXTRADE project aims to develop new fields of development of permanent rare earth type magnets present in the WEEE, targeting 3 types of electronic devices: i) hard drives of computers, ii) loudspeakers of audio and video materials and iii) the small electric motors present in ICT (information and Communication Technologies) and small electronic appliances see figure 5. Methods Several possibilities were explored to extract the NdFeB type magnetsfrom the three targeted samples of the Extrade project. The first one deals with the recovery of magnet from WEEE stream by manual or mechanical dismantling. After identifyingthe NdFeB type magnets in different collected electronic devices of WEEE, the materials were subjected to liberate the magnets manually by using different tools. The main objective of this action is to minimize the time and thus the labor cost to remove the magnets from the three project"s targets. Concerning the mechanical dismantling, different shredders were used on the investigated demagnetized samples. The objective is to choose the most available equipment which can liberate the magnets.

The sortedNdFeB type magnets were crushed and a physical separation technique was used in order to remove the metal coating (figure 6). The objective of this operation wasto produce a powder rich in rare earth elements (Nd, Dy and Pr), which can be treated by hydrometallurgical techniques to recover REEs selectively. The valorisation of NdFeB type magnets of HDD requires beingable to isolate the magnets and therefore to selectively fragment the HDD structure that preserve the integrity of these magnets. One of the technologies identified to achieve this fragmentation is the electrofragmentation equipment developed by SELFRAG(Figure 7 left). It involves applying high voltage electric pulses (Figure 7 right), (few kV per cm), through complex multi-phased or multi-constituents matrices, immersed in a dielectric liquid (water preferably). The spread of these impulses in the water and in the solid is materialized by electric arcs that propagate preferentially at the interfaces between mineral phases of ores or components of waste and which lead to a smart, selective crushing of HDD and so, to the release of permanent magnets contained.

Figure 7 -Physical and electrical requirements for the Selfrag process

The equipment set-up for the tests was using a 2 L closed vessel and a standard electrode (8 mm). The objective was to investigate the selective liberation of the three targets of the Extrade project. Six samples were processed using appropriate conditions.

RESULTS

Characteristics of permanent magnets

The three representative samples were dismantled for characterisation. The first action deals with determination of Wt% of magnets in the investigated electronic devices. The results are shown in Table 2. It can be seen that, central unit computer HDD, loudspeakers, laptop and electric motors contain respectively, 2.5 -2.8 wt%, 4 -6 wt %, 22 -26 wt % or 0.8 -2 wt % of magnets.

Sources

Weight % of magnet Characterization of the magnets was performed according to method described (N. Menad and A. Seron, 2016). Figure 8 show the morphological aspects of the investigated sample of magnet obtained by scanning electron microscopy (SEM). Figure9 shows that the Ni or Zn protective coating of magnet consists of a layer of approximately 20 µm thick. The texture of these magnets consists of sintered crystals of Nd 2 Fe 14 B phase tetrahedral shape and rich rare earth oxides (Nd, Dy and Pr) at interphase (see EDS in figure 8).

Thermal treatment (demagnetization)

Permanent magnets have several physical properties, including the Curie temperature and maximum operating temperature which differ from a type of magnet to another. The Curie temperature (T c ) is the temperature above which a magnetic body loses irreversibly its magnetization. When heating a magnetic material above this temperature, the order of the magnetic fields disappears to a paramagnetic disordered state. The maximum operating temperature (T max ) is the temperature at which the magnet loses its magnetic property but remains usable after cooling. It is important to underline that T max is a function of the size of the magnets.

To determine those parameters, TGA was carried out on the investigated samples. About 15g of the investigated samples (whole magnets) are heated in nitrogen atmosphere until 500°C with temperature rate of 2°C min -1 in a specific way in order to determine physical properties, particular Curie temperature at which the magnets lose their magnetic properties.The results are shown in Figure 10. It can be seen that the effect for loudspeakers permanent magnet is at 459°C, this can be attributed to the Curie temperature of ferrite magnets. However, for HDD, two effects are observed. The first one is started at 145°C, which is attributed to their maximum operating temperature, and the second one at 297°C. Thelast one is attributed to the Curie temperature of the rare earth type magnets at which they lose their magnetic properties. Then, to demagnetize the NdFeB and ferrites type magnets, it must be heated, respectively, at the temperatures around 300°C and 500°C.

Manual dismantling Strictly manual disassembly

Different tools of market were used to perform this task. By investing in learning optimized movements, repeatability and durability, it is possible to minimize the time of this action, which is incompressible due to the number of screws and change of tools. A significant time remainsnecessary to extract the magnets from their support.

Semi-mechanized disassembly

To save time by avoiding total manual disassembly to get near-identical own fractions, hacksaw and stand drill were tested. The results show that the drill gives the same disassembly time than manual process, however it offers two significant advantages. It requires less effort and it allows delivering strong screws, while the hacksaw provided no benefit.

Mechanical dismantling

Different shredders that can be found in mineral processing were tested. The objective was to liberate the magnets contained in the three investigated samples of electronic devices. From several shredders tested, only one allowed to liberate around 98% of magnets. The results will be patented. As shown in figure 11, the products generated are classified in different fractions, and the fractionenrichedin magnets was subjected to physical separation to recover selectively all magnets.

Electrical (high-voltage electric pulses)treatment

The results obtained from electro fragmentation tests show:

1. After only 10 pulses the hard disc itself began to "swell" and surface components started to become liberated. After 40 pulses, internal components started to be liberated and by 80 pulses, the entire drive was separated into distinct components (casing, hard drive, motor, etc.). With 120 pulses, there was liberation and size reduction of the all parts, except for the metal casing.

2. Regarding the small electrical motor 1, the magnet was immediately fragmented upon the application of 10 pulses and the internal coils were separated from casting after 50 pulses and by adding the energy the tightly wound copper wires began to liberate.

3. Only 10 pulses were needed to liberate the electrical motor 2 from the board along with the internal components of the motor, and any additional energy was used to fragment said components further as well as remove those still attached to the circuit board (Figure 12) The dissolution of the magnet powder was carried out by using a weak acid. The solution obtained contained Nd, Dy, Pr and high content of iron present in the form of Fe 2+ and Fe 3+

.

The results are reported in Figure 13. It shows the evolution of the dissolution rate of magnet as function of the time. From this figure, it can be concludedthat all metals are dissolved in 7 hours exceptnickel which is stable and can thus be recovered in the solid phase after filtration of the solution. It is important to note that this result is under processing of patent.

The precipitation tests of the solution containing ion metals by NaOH were performed at different pH. The results are given in Figure 14 showing the evolution of the precipitation rates of Nd, Dy and Fe as function of pH. From this figure, it can be seen that at pH lower than 4, about 80% of iron is precipitated in the form of Fe +3 , while Fe +2 will be totally precipitated at pH = 10 with Nd and Dy. As the precipitation of those elements contained in the solution is notselective, several tests were carried out on the useof different biomaterials to selectively extractthe ion metals contained. The test results of sorption of rare earths on solutions (Figure 15) clearly show that some biomaterials allow a specific extractionof dissolved iron and consequently enrichment in REEs ofthe solution.Such a process seems to be able to lead to a quantitative separation of iron and rare-earth elements. Other Experiments are under way to optimize the conditions for implementation. The process subjected to patenting procedure will lead to the protection of a process from the preparation of constituent elements solution of the magnets up totheir separation before their recovery. 4. CONCLUSIONS From the characterization of the small household flow, the magnets present in hard drives, small electric motors and speakers, represent around 98% of the magnet deposit collectable in the small electronic appliances flow. The rest of the magnets in this stream is disseminated in other equipment such as fixed or mobile phones, internet boxes which cannot be easily sorted regarding the current processing treatment chain.

The best way to reduce the time of manual disassembly of the electronic devices containing NdFeB type magnets is to recover the magnets still stuck on the stainless steel carrier at the stage of downstream valorization.

The results of the thermal treatments show that the majority of the magnets present in the three investigated electronic devices lose their magnetic properties in reaching the Curie temperature (300-400 ° C) in 15-20 minutes.

Pilot-scale trials on mechanical dismantling of hard drives to recover the magnets give encouraging results. More than 87% of magnets were released without pulverizing them. An innovative physical separation technique will be tested on the class-20 mm to extract contained magnets.

Fragmentation of the investigated samples of the electronic devices containing magnets in the SELFRAG process is easily achieved. For material completely encased in metal, the liberation is difficult, but not impossible. The initial energy required to "break in to" to casing and loosen it may be high, but once liberation is initiated, it tends to propagate rapidly. Any exposed components are quickly broken down, especially liberating plastic from metal Physical and chemical techniques are developed to extract the magnet coating. A mass balance of the developed process will be performed.Dissolution test results with weak acid show that magnet-alloys are dissolved in 7 hours while the coating of Ni or zinc is not attacked.

The precipitation study of cations of the solutions obtained from dissolution of magnets with NaOH shows that at pH 3, approximately 80% of Fe (III) areprecipitated; the remaining 20%are in thedissolved iron (II)form. The co-precipitation of iron (II) with REEs starts at pH > 3.Consequently, 6 biomaterials have been tested to extract iron and enrich the solution in REES. From thesebiomaterials tested for theirselective adsorption capacity of REEs, two have given encouraging results.

Figure 1 :

 1 Figure 1: World demand and supply of rare earth (Dudley Kingsnorth, /2012)

Figure 2 :

 2 Figure 2: Criticality of REEs in long term (Gareth P Hatch, 2013) 1.2.Application of REEs The majority of REEs are used in high technology, especially in the manufacture of high performance magnets, in phosphors present in color televisions or energy saving lamps, catalytic converters, batteries for mobile phones and magnetic alloys. REEs are also used in medical applications (medicines, ophthalmology, NMR, IRM, etc...).

Figure 3 :

 3 Figure 3: Application of REEs and production places of rare earth magnets

Figure 4 :

 4 Figure 4: Extrade process to be developed

Figure 5 :

 5 Figure 5: Electronic devices containing REEs 2.2.Methods Several possibilities were explored to extract the NdFeB type magnetsfrom the three targeted samples of the Extrade project. The first one deals with the recovery of magnet from WEEE stream by manual or mechanical dismantling. After identifyingthe NdFeB type magnets in different collected electronic devices of WEEE, the materials were subjected to liberate the magnets manually by using different tools. The main objective of this action is to minimize the time and thus the labor cost to remove the magnets from the three project"s targets. Concerning the mechanical dismantling, different shredders were used on the investigated demagnetized samples. The objective is to choose the most available equipment which can liberate the magnets.

Figure 6 :

 6 Figure 6: Physical process of purification of magnet powder The NdFeB powder was dissolved by a new simple method and the REEs were selectively recovered by several tested sorbents. All products generated form the cited methods were characterized by XRD, SEMand chemical analyses.

Figure 8 :

 8 Figure 8: Morphological aspects and EDS of HDD magnet

Figure 10 :

 10 Figure 10: TGA of permanent magnets of HDD and loudspeakers

Figure 11 :

 11 Figure 11: Process recovery of permanent magnets from electronic component.

Figure 13 :

 13 Figure 13: Dissolution kinetics of magnet Figure 14: Precipitation of Nd, Fe and Py

Figure 15 :

 15 Figure 15: Selective sorption of REE using biomaterials (biomaterials A, B, C, D, E, F)

Use China USA Japan & SE Asia Others Total Market Share, %

	Permanent Magnets 28000	2000	4500	1500	36 000	22
	Metal Alloys	20000	2000	2500	1500	26 000	16
	Catalysts	14500	6500	2500	1500	25 000	15
	Polishing Powders	19000	3000	2000	1000	25 000	15
	Phosphors	9000	1 000	2000	500	12 500	8
	Glass Additives	6000	1000	1000	1000	9 000	6
	Ceramic	4000	2 000	2000	1000	9 000	6
	Other	6500	8000	3500	2000	20000	12

Total Demand 107000 25500 20000 10000 162 500 100

	Market Share	66%	16%	12%	7%	100%

Table 1 :

 1 Forecast for Global demand of REEs end uses (Source: IMCOA)

Table 2 :

 2 Weight percent of magnets in different electronic components

	Computer loudspeakers	4 -6
	HDD from central unit computer	2.5 -2,8
	HDD from Laptop	2 -3
	Small electric motors (A)	22 -26
	Small electric motors (B)	0.8 -2

ACKNOWLEDGEMENTS

This work presented herein was performed in the frame of contract N° ANR-13-ECOTS-0006-01. The authors gratefully acknowledge the financial support of the French National Research Agency which has made this collaboration possible, Team2 and other partners of the research project for samples and discussions: Galloo, GPM Rouen, Eco-systèmes, Selfrag and Cyclamen. The authors also thank the reviewers for their constructive comments.