Total Germanium Recycling from Electronic and Optical Waste

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Kinetics, Catalysis, and Reaction Engineering

Total germanium recycling from electronic and optical waste Jakub Bumba, Pavel Dytrych, Radek Fajgar, Frantisek Kastanek, and Olga Solcova Ind. Eng. Chem. Res., Just Accepted Manuscript • DOI: 10.1021/acs.iecr.8b01237 • Publication Date (Web): 07 Jun 2018 Downloaded from http://pubs.acs.org on June 7, 2018

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Industrial & Engineering Chemistry Research

Total germanium recycling from electronic and optical waste Jakub Bumba, Pavel Dytrych, Radek Fajgar, Frantisek Kastanek, Olga Solcova* Institute of Chemical Process Fundamentals of the CAS, v. v. i., Rozvojova 135/1, Prague 6, Czech Republic ABSTRACT: The method of germanium and silicon regeneration from waste germanium lenses and photovoltaic cells was successfully verified with the total yield of germanium of above 97 w%. The preparation of magnesium germanide, magnesium silicide and their mixtures in an optimized semi-opened reactor was investigated in details. Obtained products were characterized by dispersive Raman spectroscopy, Scanning Electron Microscopy with Energy Dispersive X-Ray Spectroscopy (SEM/EDX) and X-Ray Diffraction (XRD), which confirmed high conversion, homogeneity and crystallinity of prepared products. The measured data, together with data obtained from literature, served as input parameters for a mathematical model. Subsequent hydrolysis of prepared products to obtain germanium and silicon hydrides was observed by Fourier Transform Infrared Spectroscopy (FTIR) and by gas chromatography mass spectrometry (GC/MS). A successful separation of hydrolysis products to individual hydrides was also performed. Magnesium hydrogen phosphate trihydrate, a desired fertilizer, and the only byproduct of the whole process, was crystallized out from hydrolysis residue with the purity of over 95 %.

1.

germanium tetrachloride, then hydrolyzes to oxide, and finally, reduces to pure germanium by means of hydrogen or carbon. Further refining is required for high-purity germanium. For this procedure, stringent regulations must be in place to transport and use Cl2, and HCl, including corrosion-resistant facilities and precautions to rigorously maintain worker exposure for Cl2 and HCl, respectively. Many of these precautions must be maintained to manipulate downstream chlorides, which are generally moisture-sensitive and corrosive. The combination of these features creates clear motivations to replace Cl2 and its associated products with more environmentally sensitive and cheaper alternatives.8, 9, 10

INTRODUCTION

The demand for germanium in the field of semiconductors, electronic and optical devices has been rapidly growing; however, resources of germanium are rather scarce worldwide.1 By far the most important application of germanium is the manufacture of semiconductors. Nevertheless, the new use of germanium in high technological industrial applications, which caused the scarcity of germanium resources, has increased its price up to 2000 USD/kg in 2015. Therefore, it has been attractive to process raw materials and electronic scrap even of a very low germanium content. This fact initiated significant efforts to improve the efficiency of germanium extraction and refining, similarly as recycling from waste products.

Germanium has often been used in combination with silicon for transistor, processor and photovoltaic applications. Silicon recovery is usually based on waste leaching and the subsequent conversion to silicon chlorides followed by purification steps and thermal decomposition. Vital Materials Limited Company (Guangdong Xiandao Rare Material Co. Ltd., 2011) processes solar panels containing materials such as indium and gallium using hydrometallurgy, after fine grinding to recover the materials from solar panels. Their process includes a liquid extraction, with gallium salt and lithium salt added to the water extraction; separation; recycling; filtering; etc.11, 12 Lin and Tai studied the recovery of silicon from kerfs loss slurry by a phase-transfer separation method. The best result obtained was 71.1% in overall recovery and 99.1 wt% in Si purity. 13, 14 Wang et al. proposed the process which reached almost 62% recovery of silicon material.13, 15 O.

Nowadays, Ge is mainly gained as a by-product of zinc ore processing.2, 3 About 30 % of Ge used in the world is obtained from recycled electronic devices and optical fibers. Sometimes germanium is contained in coals, particularly in coal-combustion by-products; especially in fly ash. Therefore, many studies have focused on the recovery from fly ash.4, 5, 6 The basic procedure of obtaining germanium from solid wastes was leaching by hot sulfuric acid. Many techniques were applied to separate Ge from other elements contained in leachates such as precipitation, adsorption, solvent extraction, adsorption on chelating, exchange resins, ion-exchange extraction, vacuum reduction metallurgical process, etc.7 After the Ge concentration reaches a certain value, germanium converts into

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Solcova et al.16 introduced a low temperature recycling process of silicon waste via magnesium silicide preparation with subsequent hydrolysis to silane. C.R. Clark et al.17 tried to prepare magnesium silicide and germanide by mechanical alloying in a ball mill. Despite using pure raw materials, even after 14 hours, no total transformation to intermetallic product occurred. F. C. Gennari et al.18 observed that even after 330 hours of milling, the preparation of magnesium germanide was not completed. One Chinese invention189 has described the preparation of magnesium germanide in a furnace tube under vacuum at 500 – 600°C for 1 – 3 hours to make the reaction fully perform. E.Ratai et al. prepared Mg2Si from stoichiometric amounts of ultrapure magnesium in sealed tantalum ampules under the reduced pressure of ≈ 0.2 atm of argon and then heated at the rate of 60 °C/h to 700 °C for 3 days.18

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Magnesium germanide, similarly as magnesium silicide, can be used as a raw material for the germanium hydride (germane) preparation by hydrochloric acid hydrolysis with hydride reagents such as sodium borohydride.21 The reaction with borohydrides is catalyzed by various acids and can be carried out in either an aqueous or organic solvent.Error! Reference source not found. A typical synthesis involved the reaction of Na2GeO3 with sodium borohydride. Error! Reference source not found. Other methods for the synthesis of germane include an electrochemical reduction and a plasma-based method.Error! Reference source not found. Germane can be decomposed to hydrogen and germanium at about 300 ° CError! Reference source not found. due to its temperature instability, which is widely utilized in electronic and semiconductor applications, where germane is applied as a source of germanium for a chemical vapor deposition method (CVD).Error! Reference source not found. This work is focused on widening the new method of silicon recovery from waste photovoltaic panels.10 The possible application on electronic waste containing germanium and germanium/silicon mixtures was tested. For the synthesis, a different content of germanium and silicon scrap in raw mixtures was used to describe the recovery from various types of germanium and magnesium wastes. The low-temperature preparation of magnesium germanide and/or magnesium silicide from waste starting mixtures, together with the obtained products, was studied in detail. Subsequently, the separation of individual germanium and silicon hydrides, including their mixtures prepared by hydrolysis with phosphoric acid, was suggested and verified. All products were characterized by various techniques with a special attention to possible hydrolysis byproducts.

2. EXPERIMENTAL 2.1. Materials and experimental conditions Partially oxidized magnesium chips, waste germanium lens and silicon of end-of-life photovoltaic panels were used as raw materials for the preparation of magnesium germanide, magnesium silicide and their mixtures. Magnesium possessed a particle size of less than 200 µm and 97 % purity containing 3 % of Mg-O (Fichema s.r.o.), the purity of germanium lens pieces was 99.999 % (Alkor Technologies) and purity of photovoltaic panels scraps achieved 90 % with Si-O content less than 10 % (Solartec). Pieces of germanium lens and scraps of photovoltaic panels were milled separately into powder with the grain size of less than 50 µm. After milling, powdered materials were mixed in various molar ratios (see Table 1) and finally homogenized.

B


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Table 1: Molar ratios of germanium and silicon in raw mixtures.

dropping funnel with a phosphoric acid solution. The second neck was connected to a vacuum pump and FTIR Sample

In all cases, 2.1 molar ratio of magnesium (5% excess) was applied to compensate its evaporation during the reaction. The total weight of raw materials filled into the reactor was 10 g in all cases. The filled reactor was then evacuated at 120°C (time 0) and heated to final temperature.

S1

S2

1:0

0.75 0.25

S3

S4

S5

Mg 2.1 versus Ge : Si [mol tio]

2.2. The reactor and its arrangement The experiments were performed in a semi-opened tube reactor (see Figure 1), which is a small stainless steel tube with a sealed bottom at one end and a vent-hole at the other end. The vent-hole enabled continual evacuation of air and impurities from the reactor. Moreover, its small diameter (1 mm) prevented strong evaporation of magnesium during the reaction. The used reactor possessed the length of 23.5 cm, inner diameter of 1.4cm and volume of 36 cm3. The reactor after being filled by the reaction mixture was inserted into a quartz tube and evacuated. After stabilizing the pressure at 5 Pa, which was the limit for the used vacuum pump, the quartz tube with the reactor was put into the tube furnace and the set-up was ready for an experiment. The reactor was heated up to 400°C with the temperature rate of 15°C/min. The end of the reaction was detected by pressure changes. After reaching the starting value of pressure again, the heating was turned off and the furnace was removed. The system was cooled down at laboratory temperature and the prepared samples were observed by analytical methods.

:

0.5 0.5

:

0.25 0.75

:

0:1

ra-

cuvette for sample collecting. The device was evacuated after the constant pressure of 5 Pa was achieved. In the next step, phosphoric acid was slowly dropped into the flask with the sample, and the resulting gaseous product was collected in the FTIR cuvette. The collected gas samples were then characterized by FTIR and GC/MS.

2.4. Analysis procedure Obtained products and raw materials were characterized by X-Ray Photoelectron Spectrometer (XPS), Scanning Electron Microscopy (SEM) with Energy Dispersive X-Ray Spectroscopy (EDX), X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), and Fourier Transform Infrared Spectroscopy (FTIR). The purity of starting materials was determined by XPS (X-Ray Photoelectron Spectrometer, Kratos ESCA 3400) and SEM with EDX. The base pressure inside the XPS chamber was lower than 5.0 10-7 Pa, and as a source of X-Ray, the polychromatic Mg Kα at 1253.4 eV was used. The XPS spectra were charge corrected by the C 1s spectral component binding energy set to 284.8 eV for Si, SiOx, Mg, MgOx, Mg2Si, Ge, GeOx, Mg2Ge samples. The spectra were fitted using a Gaussian–Lorentzian line shape, Shirley background subtraction and a damped non-linear least square procedure. Spectra were taken over Si 2p, Ge 3d, 2p, Mg 2p, O 1s, C 1s and valence band regions. Samples were repeatedly sputtered with Ar+ ions at 1 kV with the current of 10 µA for 30 s to remove superficial layers.27 Conditions of SEM/EDX (Tescan Indusem) measurement: The SEM with mounted EDX was used for composition evaluation of products based on intensity ratios of Mg Kα, Si Kα and Ge Kα. Tungsten substrates were used as a support of the layers measured by EDX at acceleration voltage 15 - 30 kV. Gold plates with a thin layer of studied material on the surface were attached using adhesive material to non-diffracting sample holders. The composition of solid products was characterized by XRD in a continuous scan on PANalytical X’Pert PRO equipped with a fast X’Celerator detector and PW3050/60 (Theta/Theta) goniometer. The polychromatic Cu Kα1: 1.54060; Kα2: 1.54443; Kβ: 1.39225 [Å]; Kα2 / Kα1 Ratio: 0.50000 without monochromator was used. XRF measurements were used for an elemental composition on ARL 9400 Rh using 60kV LiF200 LiF220 Ge111 TlAP. The elemental composition was evaluated from peak shapes and impact factors.

Figure 1: Semi-opened tube reactor.

2.3. Hydrolysis of prepared samples Samples of magnesium germanide, magnesium silicide and their mixtures were hydrolyzed by phosphoric acid (25 % (w/w) H3PO4) at laboratory temperature. 200 mg of samples were put into a two-neck round-bottom flask with a magnetic mixer. The first neck was closed by a

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The FTIR spectra of gaseous hydrolysis products before cooling and silane decomposition were measured on an Nicolet spectrometer with the spectral resolution of 1 cm-1 with 100 repetitions. All Raman dispersive spectra were collected in 256 exposures with the excitation wavelength of 473 nm (power of 8-10 mW) and resolution of 2 cm-1. The gas chromatography–mass spectroscopy (GC-Hewlett Packard 6890 series, MS-5973 Mass selective protector), using a 30 m long DB-5 capillary column (diameter = 0,25 mm), programmed to 35–290 °C with temperature increase of 10 °C/min, helium carrier gas (flow = 1 ml/min) with injector temperature of 130 °C and sampling by a gastight syringe after He (atmospheric pressure) were used for the detection of hydrolyzed products. The products were also observed by a dispersive Raman Nicolet Almega XR Spectrometer.

Figure 2: Pressure dependence on time at rising temperature during magnesium germanide preparation.

3. Results and Discussion

A rapid increase of the pressure ca. 20 minutes after the start of heating is evident. This step change of the pressure was caused by magnesium sublimation, which allowed for the acceleration of the reaction rate. It was confirmed by a short stoppage of the temperature increase caused by heat utilization for phase transition of magnesium. It is obvious that sublimation of magnesium started at about 400°C.The subsequent pressure drop was caused by the quick reaction of magnesium vapor with germanium. This decrease of pressure to the starting value represented the end of the reaction, which did not exceed 25 minutes. It should be stressed that the course of the pressure curve was the same for all tested samples with different ratios of Ge:Si (S1-S5). The composition of obtained products was characterized by XRD. The results are summarized in Table 2.

The reuse of germanium and/or silicon from waste electronic scrap belongs to the most important challenges. In our previous manuscript10 we showed that the recovery of silicon from waste photovoltaic panels can be advantageously done through magnesium silicide with subsequent hydrolysis. Based on this knowledge, the application of the developed procedure on waste electronic scrap containing germanium and/or silicon was tested. An optimized semi-opened tube reactor under continuous vacuum was applied for the preparation of magnesium germanide, magnesium silicide, and their mixtures. These reactions belong to solid-solid reactions; however, magnesium can partially sublimate under particularly used reaction conditions. The standard formation enthalpy of magnesium silicide at temperature of 25 °C is approximately -77.8 to -79.1 kJ/mol for the solid-solid reaction (Equation 1) and -373.5 kJ/mol for the gas-solid reaction (Equation 2).28, 29 The reaction enthalpy of magnesium germanide at the temperature of 25 °C is approximately -115 kJ/mol for solid-solid reaction Equation 3.30 2 Mg (s) + Si (s) -> Mg2Si (s)

(1)

2 Mg (g) + Si (s) -> Mg2Si (s)

(2)

2 Mg (s) + Ge (s) -> Mg2Ge (s)

(3)

Table 2: Composition of products prepared from samples in semi-opened tube reactor at 400 °C for 25 min from XRD. Sample

Mg2Ge

Mg2Si

Mg

Ge

Si

Products [w %]

To obtain information on the whole ratio of Ge : concerning Si ratios (see Table 1), five various molar ratios were tested. In all cases, 2.1 molar ratio of magnesium (5% excess) was applied to compensate its evaporation during the reaction. Figure 2 demonstrates the pressure dependence on time at temperature up to 600°C during the magnesium germanide preparation.

S1

95.0

-

3.0

-

-

S2

77.0

20.0

2.0

0.5

0.5

S3

60.0

38.0

-

-

-

S4

20.0

70.0

2.0

-

4.0

S5

-

97.9

2.0

-

0.1

It is evident that conversion of raw materials to products was over 95 % in all cases. The purity of prepared magnesium silicide achieved almost 98 % and 95 % in the case of magnesium germanide. The most valuable material, germanium, was almost totally converted to the desired

D


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product - magnesium germanide with the yields of at least 99.5 w% related to germanium. The remaining mass reaching up to 100 %, which varied between 0 – 4%, corresponded to weak signals on XRD patterns. Matching these weak signals to particular products appeared a bit uncertain. Based on the results of product purity and reaction course knowledge, the mathematical model, which describes the dependence of product formation on temperature including dependence of each component concentration on time, was designed and tested. The transition of magnesium and silicon to magnesium silicide (Equation 1) was modeled by a series of differential equations for the mass and enthalpy balance (dH_reaction = - 77.8 kJ/mol28, activation energy Ea = 116 kJ/mol31). The input parameters used for modeling were: Mg0 = 2.1, Si0 = 1, Mg2Si0 = 0, T0 = 298 K, Tmax = 650 K, Q0 = 1e6, Q = 750, n = 20000, m = 3600, k0 = 0.05, Cp,apparatus = 3.0e4 J, dHreaction = 77500 J/mol, A = 1e16, Ea = 120.0e3, Rg = 8.314 J/mol/K.

Figure 4: Simulated dependence of components concentration on time. The experimental data depicted in Figure 3 were measured by XRD after the preparation of magnesium silicide in a semi-opened tube reactor under the pressure of 5 Pa with the temperature rate of 15°C/min. The experiments were performed to find the minimal reaction temperature for the total conversion of silicon to magnesium silicide. Therefore, the reaction was interrupted at various temperatures, which allowed the product analysis and the calculation of conversion with the experimental error of 5 %.

The change of entropy during the chemical reaction was negligible compared to reaction enthalpy; thus, it was not taken into account. To obtain the most reliable input parameters, our experimental data, together with the data obtained from literature28, 31, were employed as the input parameters. The heat capacity of the system – the reactor and furnace, as well as the power output of the furnace, was obtained by fitting our experimental data in the course of Mg2Si preparation. Modeled results are summarized in Figures 3 and 4, where the modeled and experimental data curves representing the dependence of Mg2Si formation on temperature and simulated curve of components concentration on time during the magnesium silicide preparation in the focused area are depicted. Apparently, the model curve shows a good adherence to experimental data. However, the quick acceleration of the reaction rate caused by magnesium sublimation is relatively underestimated in the model.

The model depicted in Figure 4, based on the experimental data, describes the concentration decrease of raw materials (Si, Mg) together with the concentration increase of the product (Mg2Si) during the reaction. With the rate of 10°C/min and the final temperature of 400°C, it is can be seen that the reaction started at the temperature of about 350°C (5 minutes at Figure4) and ended approximately at 400°C. This was obtained in 6.5 minutes. Between these temperatures, the concentration of Mg and Si rapidly decreased and the concentration of Mg2Si increased accordingly, which corresponded to the experimental data. The elemental composition of prepared samples and distribution of elements were characterized by the EDX technique. Elemental mapping of S1 (pure Ge/Mg) and S5 (pure Si/Mg) was measured using sub-micrometer electron beams. The spot size and distribution of investigated elements in the reaction products are depicted in Figure 5. Both products, Mg2Ge and Mg2Si, revealed fine-grained textures with high homogeneity. The same results concerning homogeneity and fine-grained texture were obtained for all mixed samples, S2-S4. The fine crystalline structure of all products obtained by XRD, which is shown in Table 2, was corroborated by Raman spectroscopy. The Raman spectra (Figure 6) depict the characteristic phonon modes of magnesium silicide and germanide crystalline structures at about 250 cm-1, which closely corresponds to literature (254.5 cm-1 and 255 cm-1 for

Figure 3: Simulated dependence of Mg2Si formation on temperature.

E



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Mg2Ge and 258.3 cm-1 and 258.5 cm-1 for Mg2Si)32, 33, where Mg2Si represents 258 cm-1 and Mg2Ge 255 cm-1. It is also evident that almost no peaks of germanium and silicon are visible in the spectra, which demonstrates an efficient reaction of both elements and magnesium.

Figure 5: SEM/EDX of Mg2Ge prepared from S1 (left) and Mg2Si prepared from S5 (right).

Figure 6: Raman spectra of all prepared samples.

Figure 7: GC-MS of gaseous product of hydrolysis by phosphoric acid: S1) Mg2Ge; S2) Mg2Si and Mg2Ge mixture; S3) Mg2Si and Mg2Ge mixture; S4) Mg2Si and Mg2Ge mixture; S5) Mg2Si.

The uniform distribution of components and large active surface of small grains enabled a rapid reaction in the next step, which was hydrolysis by phosphoric acid. The resulting gaseous products according to Equation 4, 5 and their combination were collected for GC/MS and FTIR measurements.10 Mg2Si (s) + H3PO4(l) -> Mg(HPO4) (aq) + SinH2n+2

Mg2Ge (s) + H3PO4(l) -> Mg(HPO4) (aq) + GenH2n+2 (5) Based on Figure 7, where GC/MS spectra of all five samples are shown, it is obvious that the main product of Mg2Ge hydrolysis was digermane, and the main product of Mg2Si hydrolysis disilan. The dominant products for hydrolysis of Mg2Si and Mg2Ge mixtures were trisilane

(4)

F


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and other corresponding silanes, germanes and even germylsilanes; see Figure 7 S2, S3 and S4. FTIR spectra of gaseous hydrolysis products of pure Mg2Ge, Mg2Si and their equimolar mixture shown in Figure 8 confirmed the presence of germanium and silicon hydrides by characteristic vibrations, which corresponds to literature data.34 All samples also contained a small amount of water. It is evident that in all cases the gaseous products contained mixtures of various germanes and silanes. Owing to that, the boiling points of all possible hydrolysis products are sufficiently different (see Table 3) regarding the separation of the compounds by distillation. The fraction distillation was tested as a suitable separation method. The gaseous products of hydrolysis were initially collected in a glass finger immersed in liquid nitrogen and then gradually heated. Based on boiling points of the frozen compounds, the mixture was fractioned and the gaseous products were continuously characterized by FTIR. For this purpose, the finger was purged by a nitrogen flow and products in the carrier gas were measured in a flow cell equipped with NaCl windows. Table 3: Boiling points of individual hydrolysis products. Compound

Boiling point (°C)35, 36

SiH4

−111.8

GeH4

−88.1

Si2H6

−14.3

H3Si-GeH3

+7.0

Ge2H6

+29.0

Si3H8

+53.1

i-Si4H10, n-Si4H10

+101.7, +108.1

Ge3H8

+110.5

Ge4H10

+176.9

H5Ge2-SiH3

-

G



Figure 8: FTIR of gaseous products of hydrolysis by phosphoric acid: S1) Mg2Ge; S3) Mg2Si and Mg2Ge mixture; S5) Mg2Si. tion. Compounds (from above): Silane, germane, disilane, digermane. FTIR spectra of separated products (original S3) are shown in Figure 9. The figure shows 50 subsequent scans collected during fraction distillation. Each scan was collected for 60 second and gradual evaporation of the individual products was easily monitored. It is obvious that the effective separation based on big differences in boiling points was successfully verified. Even the compounds with high boiling points were collected as a gaseous product. The only byproduct of hydrolysis was hydrolysis residues remaining in the liquid form. Therefore, the mentioned aqueous solution was evaporated, and the obtained solid product was characterized by SEM/EDX and XRD. The EDX analysis (Figure 10) shows elements contained in the solid hydrolysis byproduct. The presence of phosphorus, magnesium and oxygen correlates with the expected magnesium phosphate byproduct according to Equation 4 and 5. To obtain the exact composition of studied byproduct, the XRD characterization was employed.

1 st min. Intensity (arb. units)

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3 rd min.

7 th min.

11 th min. 2400

2000

1600

1200

800

Wavenumbers (cm -1 )

Figure 9: Upper picture: Continual FTIR spectra during distillation of freeze-dried gaseous product of Mg2Si and Mg2Ge mixture (S3) hydrolysis by phosphoric acid. Lower picture: spectra of products as measured during fractiona-

Figure 10: EDX analysis of solid hydrolysis byproduct.

H


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Table 4: Composition of (s) hydrolysis byproduct by XRD. Chemical formula

Content (mass %)

Mg (HPO4) (H2O)3

> 95

Si Ge

conversion at least. The reaction rate was accelerated by magnesium sublimation at about 400°C (5 Pa), which caused the quick pressure increase reaching up to approximately 250 Pa with the subsequent sharp drop corresponding to the end of the reaction. Nearly the same pressure course was modeled by mathematical simulation of studied reactions. It is apparent that high conversion of raw materials and short reaction time correspond to the solid-gas reaction. Prepared magnesium germanide and/or silicide possessed the homogeneity, crystalline structure and fine-grained texture with high purity, which was confirmed by SEM/EDX, XRD and Raman spectroscopy. These properties allowed for successful hydrolysis by 25 % (w/w) H3PO4 and resulted in gaseous products; mixtures of silanes, germanes and even germylsilanes whose composition dependeded on waste materials used. The gaseous mixture of prepared hydrides was successfully separated into individual gaseous products of excellent purity by distillation due to great differences in their boiling points. The only byproduct was magnesium hydrogen phosphate trihydrate, which is a desired fertilizer. Isolated gaseous products can be utilized as a very desired CVD precursors for thin semiconductor layer-deposition in electronics and catalysis. Isolated products have various applications in metallurgy, chemistry, electronics and energetics. Moreover, silanes and germanes could be thermally or radiofrequently decomposed to ultrapure elements (Ge, Si) applicable either for electronic or optical lenses, and hydrogen applicable for chemistry or energetics.

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Total Germanium Recycling from Electronic and Optical Waste

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