Impact of Grinding of Printed Circuit Boards on the Efficiency of Metal Recovery by Means of Electrostatic Separation
Abstract
:1. Introduction
2. Materials and Methods
2.1. Grinding Materials and Methods
- option 1—1 mm screen perforation, mill load (capacity of feeding the material to the mill): 5 g/min;
- option 2—1 mm screen perforation, cooling the feed with liquid nitrogen, mill load: 20 g/min;
- option 3—2 mm screen perforation, mill load: 10 g/min;
- option 4—3 mm screen perforation, mill load: 10 g/min.
- rotator speed: 2815 min−1;
- gap between the knives in the mill: 0.5 mm.
2.2. Electrostatic Separation
2.3. Product Analysis
- Fritsch screens with mesh sizes of 2 mm, 1.4 mm, 1 mm, 710 μm, 500 μm, 355 μm, 250 μm, 180 μm, 125 μm, and 90 μm.
- ANALYSETTE 22 MicroTec Plus Laser Particle Sizer (Fritsch, Idar-Oberstein, Germany)—the measurement was not carried out on material obtained from grinding in a mill with a screen with 2 and 3 mm perforation due to limitations in the measurement of grain size.
- ICP-AES—using the JY2000 Optical Emission Spectrometer (by Jobin Yvon) in order to assess the content of elements in products. The source of the induction was a plasma torch coupled with a 40.68 MHz frequency generator; the products were previously dissolved.
- Specific density analysis—using Gay-Lussac pycnometers on the basis of PN-EN 1097-7:2001 with the use of ethyl alcohol with a density of 0.7893 g/cm3.
- Microscope analysis with Zeiss SteREO Discovery Modular Stereo Microscope (Carl Zeiss AG, Jena, Germany).
- High-resolution Zeiss SUPRA 35 scanning electron microscope (Carl Zeiss AG, Germany), equipped with EDAX energy dispersive X-ray spectroscopy (EDS) chemical analysis system (EDAX, Mahwah, NJ, USA).
- Qualitative phase analysis was performed with the use of a Panalytical X’Pert Pro MPD diffractometer (Panalytical, Almelo, The Netherlands), utilising filtered radiation of a cobalt anode lamp (λKα = 0.179 nm). The diffraction lines were recorded in the Bragg–Brentano geometry, using the step-scanning method by means of a PIXcell 3D detector on the diffracted beam axis, in the angle range of 20°–100° [2θ] (step, 0.05°; count time per step, 200 s). The obtained diffractograms were analysed with the use of Panalytical HighScore Plus (v. 3.0e) software with the PAN-ICSD database.
3. Results
3.1. Grinding
3.2. Analysis of the Electrostatic Separation Efficiency
4. Discussion
5. Conclusions
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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Grain Class, mm | Yield of Product, % | |||||
---|---|---|---|---|---|---|
Option 1 a | Option 1 b | Option 2 a | Option 2 b | Option 3 a | Option 4 a | |
>2.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.2 |
2.0–1.4 | 0.0 | 0.0 | 0.0 | 0.0 | 0.4 | 13.7 |
1.4–1.0 | 0.3 | 0.0 | 0.4 | 0.0 | 11.1 | 24.6 |
1.0–0.71 | 5.7 | 5.2 | 3.6 | 1.6 | 25.6 | 16.8 |
0.71–0.50 | 14.1 | 14.8 | 13.0 | 10.4 | 15.6 | 10.7 |
0.50–0.36 | 19.3 | 22.0 | 19.5 | 22.1 | 11.6 | 8.4 |
0.36–0.25 | 17.0 | 10.4 | 17.0 | 14.2 | 8.6 | 6.3 |
0.25–0.18 | 9.6 | 5.6 | 10.6 | 6.5 | 5.0 | 4.1 |
0.18–0.13 | 8.5 | 4.9 | 10.8 | 5.3 | 4.5 | 4.5 |
0.13–0.09 | 9.1 | 3.8 | 8.5 | 4.3 | 3.6 | 4.2 |
<0.09 | 16.3 | 33.3 | 16.6 | 35.6 | 13.9 | 6.5 |
Grinding Option | Yield of Product, % | Density, g/cc | ||||
---|---|---|---|---|---|---|
Waste | Intermediate | Concentrate | Waste | Intermediate | Concentrate | |
Option 1 | 71.5 | 2.8 | 25.8 | 2.61 | 5.98 | 8.78 |
Option 2 | 71.0 | 2.8 | 26.2 | 2.29 | 5.33 | 8.87 |
Option 3 | 66.7 | 6.1 | 27.2 | 2.92 | 3.76 | 7.32 |
Option 4 | 50.4 | 6.3 | 43.2 | 3.35 | 3.5 | 5.51 |
Element | Content of the Element, %, in | |||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Feed | Concentrate | Intermediate | Waste | |||||||||||
Option 1 | Option 2 | Option 3 | Option 4 | Option 1 | Option 2 | Option 3 | Option 4 | Option 1 | Option 2 | Option 3 | Option 4 | |||
Valuable elements | Cu | 17.70 ± 1.77 | 64.17 ± 6.42 | 68.50 ± 6.85 | 54.29 ± 5.43 | 38.45 ± 3.85 | 5.14 ± 0.51 | 6.68 ± 0.67 | 6.42 ± 0.64 | 7.47 ± 0.75 | 1.24 ± 0.12 | 0.17 ± 0.02 | 3.20 ± 0.32 | 3.89 ± 0.39 |
Al | 1.95 ± 0.20 | 5.28 ± 0.53 | 6.82 ± 0.68 | 4.58 ± 0.46 | 4.08 ± 0.41 | 1.18 ± 0.12 | 1.34 ± 0.13 | 0.84 ± 0.08 | 0.54 ± 0.05 | 0.2 ± 0.02 | 0.07 ± 0.01 | 0.48 ± 0.05 | 0.29 ± 0.03 | |
Pb | 0.39 ± 0.04 | 2.04 ± 0.20 | 1.5 ± 0.15 | 2.54 ± 0.25 | 1.74 ± 0.17 | 1.28 ± 0.13 | 0.74 ± 0.07 | 0.47 ± 0.04 | 0.08 ± 0.01 | BDL * | 0.001 ± 0.0001 | BDL * | 0.02 ± 0.002 | |
Zn | 0.69 ± 0.07 | 1.22 ± 0.12 | 2.5 ± 0.25 | 1.87 ± 0.19 | 0.87 ± 0.09 | 0.74 ± 0.07 | 0.94 ± 0.09 | 0.40 ± 0.04 | 0.94 ± 0.09 | 0.14 ± 0.01 | BDL * | 0.08 ± 0.01 | BDL * | |
Ni | 0.19 ± 0.02 | 1.28 ± 0.13 | 0.75 ± 0.08 | 0.49 ± 0.05 | 0.34 ± 0.03 | 0.75 ± 0.07 | 0.31 ± 0.03 | 0.41 ± 0.04 | 0.21 ± 0.02 | BDL * | BDL * | 0.18 ± 0.02 | BDL * | |
Fe | 0.38 ± 0.04 | 2.42 ± 0.24 | 0.95 ± 0.10 | 1.87 ± 0.19 | 1.11 ± 0.11 | 0.61 ± 0.06 | 1.50 ± 0.15 | 1.64 ± 0.16 | 0.84 ± 0.08 | 0.04 ± 0.004 | 0.09 ± 0.01 | 0.15 ± 0.02 | 0.40 ± 0.04 | |
Sn | 2.92 ± 0.29 | 9.54 ± 0.95 | 11.5 ± 1.15 | 9.78 ± 0.98 | 7.21 ± 0.72 | 2.57 ± 0.26 | 1.18 ± 0.12 | 1.88 ± 0.19 | 0.58 ± 0.06 | 0.15 ± 0.02 | 0.02 ± 0.002 | 1.14 ± 0.11 | 1.19 ± 0.12 | |
Cr | 0.06 ± 0.06 | 0.18 ± 0.02 | 0.15 ± 0.02 | 0.09 ± 0.01 | 0.04 ± 0.004 | 0.02 ± 0.002 | 0.04 ± 0.004 | 0.47 ± 0.05 | 0.27 ± 0.03 | 0.001 ± 0.0001 | 0.001 ± 0.0001 | BDL * | 0.04 ± 0.004 | |
Ti | 0.26 ± 0.03 | 0.39 ± 0.04 | 0.51 ± 0.05 | 0.51 ± 0.05 | 0.51 ± 0.05 | BDL * | 0.39 ± 0.04 | 0.40 ± 0.04 | 0.22 ± 0.02 | 0.21 ± 0.02 | 0.18 ± 0.02 | 0.28 ± 0.03 | BDL * | |
Ag | 0.030 ± 0.003 | 0.0647 ± 0.0067 | 0.1074 ± 0.0011 | 0.0221 ± 0.0022 | 0.0054 ± 0.0005 | BDL * | BDL * | 0.0007 ± 0.0001 | BDL * | BDL * | BDL * | BDL * | 0.0002 ± 0.00002 | |
Au | 0.0029 ± 0.0003 | 0.0010 ± 0.0001 | 0.0092 ± 0.0009 | 0.0005 ± 0.0001 | 0.0007 ± 0.0001 | BDL * | BDL * | BDL * | BDL * | BDL * | BDL * | BDL * | BDL * | |
Sum | 24.57 | 86.58 | 93.30 | 76.04 | 54.36 | 12.29 | 13.12 | 12.93 | 11.15 | 1.99 | 0.54 | 5.51 | 5.83 | |
Nonvaluable elements | Sb | 0.22 ± 0.02 | 0.27 ± 0.03 | 0.61 ± 0.06 | 0.19 ± 0.02 | 0.08 ± 0.01 | BDL * | 0.18 ± 0.02 | 0.18 ± 0.02 | 0.12 ± 0.01 | 0.21 ± 0.02 | 0.01 ± 0.001 | 0.27 ± 0.03 | 0.33 ± 0.03 |
Ca | 6.56 ± 0.66 | 0.98 ± 0.10 | 0.92 ± 0.09 | 1.12 ± 0.11 | 2.24 ± 0.22 | 2.81 ± 0.28 | 2.41 ± 0.24 | 4.78 ± 0.48 | 3.91 ± 0.39 | 8.43 ± 0.84 | 7.51 ± 0.75 | 6.93 ± 0.70 | 9.05 ± 0.91 | |
Br | 1.64 ± 0.08 | 0.08 ± 0.01 | 0.03 ± 0.003 | 0.35 ± 0.04 | 0.78 ± 0.08 | 0.78 ± 0.08 | 1.12 ± 0.12 | 1.49 ± 0.15 | 1.21 ± 0.12 | 2.11 ± 0.21 | 1.28 ± 0.13 | 1.69 ± 0.17 | 1.41 ± 0.14 | |
Ba | 0.31 ± 0.03 | 0.10 ± 0.01 | BDL * | 0.2 ± 0.02 | 0.15 ± 0.02 | BDL * | 0.41 ± 0.04 | 0.12 ± 0.01 | 0.32 ± 0.03 | 0.64 ± 0.06 | 0.77 ± 0.08 | 0.59 ± 0.06 | 0.59 ± 0.06 | |
Mg | 0.57 ± 0.06 | 0.05 ± 0.01 | 0.05 ± 0.01 | 0.28 ± 0.03 | 0.43 ± 0.04 | 0.95 ± 0.09 | 1.51 ± 0.15 | 0.64 ± 0.06 | 0.44 ± 0.04 | 2.01 ± 0.20 | 2.50 ± 0.25 | 2.10 ± 0.21 | 1.48 ± 0.15 | |
Si | 12.00 ± 1.20 | 1.21 ± 0.12 | 0.40 ± 0.04 | 7.45 ± 0.75 | 6.15 ± 0.62 | 5.68 ± 0.57 | 3.19 ± 0.32 | 6.78 ± 0.68 | 7.28 ± 0.73 | 14.48 ± 1.45 | 13.92 ± 1.39 | 11.21 ± 1.12 | 12.1 ± 1.21 | |
Mn | 0.01 ± 0.001 | 0.03 ± 0.003 | 0.03 ± 0.003 | 0.03 ± 0.003 | 0.03 ± 0.003 | BDL * | BDL * | BDL * | BDL * | BDL * | BDL * | BDL * | BDL * | |
Sum | 21.26 | 2.69 | 2.01 | 9.59 | 9.83 | 10.22 | 8.82 | 13.99 | 13.28 | 27.88 | 26.00 | 22.79 | 24.93 |
Element | Point of Analysis | ||||||||
---|---|---|---|---|---|---|---|---|---|
A1 | A2 | A3 | A4 | A5 | A6 | A7 | A8 | A9 | |
Mg | - | - | - | 6.2 | - | - | - | - | - |
Al | 1.4 | 2.3 | 19.0 | 93.8 | 22.4 | 4.1 | 5.5 | 34.9 | 4.0 |
Si | - | 1.0 | 46.8 | - | - | - | - | 3.6 | 1.7 |
Sc | - | - | - | - | - | - | 0.2 | - | 0.2 |
Fe | - | - | - | - | 3.2 | - | - | - | - |
Ni | - | - | - | - | 26.4 | - | - | - | 37.0 |
Cu | 98.6 | 96.8 | 5.0 | - | 12 | - | 3.1 | 50.9 | 45.8 |
Sn | - | - | - | - | - | 95.9 | 89.7 | 10.7 | 10.6 |
Sb | - | - | - | - | - | - | 1.6 | - | 0.7 |
Au | - | - | - | - | 36 | - | - | - | - |
Na | - | - | 1.0 | - | - | - | - | - | - |
Element | Point of Analysis | |||||||
---|---|---|---|---|---|---|---|---|
B1 | B2 | B3 | B4 | B5 | B6 | B7 | B8 | |
Mg | - | - | 1.5 | - | - | - | 1.8 | - |
Al | 3.4 | 4.6 | 13.7 | 74.8 | 6.8 | 2.4 | 8.5 | 9.9 |
Si | - | - | 20.4 | 4.6 | - | 1.2 | - | 1.2 |
Sc | - | - | - | - | 0.3 | - | - | - |
Fe | - | - | 23.1 | 1.7 | - | - | - | - |
Ni | 4.3 | - | 2.0 | - | - | - | - | - |
Cu | 17.2 | 95.4 | 26.9 | 10.6 | 5.9 | 96.4 | 89.7 | 87.3 |
Ag | 1.2 | - | - | - | 2.5 | - | - | - |
Sn | 73.9 | - | - | 6.6 | 83.6 | - | - | - |
Sb | - | - | - | - | 0.8 | - | - | - |
Ca | - | - | 4.7 | 1.3 | - | - | - | - |
Mn | - | - | 0.2 | - | - | - | - | - |
S | - | - | 0.5 | - | - | - | - | - |
Cl | - | - | - | 0.3 | - | - | - | 1.6 |
Cr | - | - | 6.7 | - | - | - | - | - |
Ba | - | - | 0.2 | - | - | - | - | - |
Metal | Price *, ($/Mg) | Metal Content in the Concentrate (Data from Table 3), % | Metal Recovery Level Related to the Initial PCB Mass (after Dismantling), % | Prices of Metals Obtained from 100 g of PCB, $ |
---|---|---|---|---|
Cu | 7635 | 68.5 | 17.95 | 1.4 |
Al | 1986 | 6.82 | 1.79 | 0.035 |
Pb | 2063 | 1.5 | 0.39 | 0.008 |
Zn | 2762 | 2,5 | 0.66 | 0.018 |
Ni | 16,390 | 0.75 | 0.20 | 0.032 |
Fe | 553 | 0.95 | 0.25 | 0.001 |
Sn | 19,128 | 11.5 | 3.01 | 0.576 |
Ag | 7.91 × 105 | 0.1074 | 0.0281 | 0.223 |
Au | 6.01 × 107 | 0.0092 | 0.0024 | 1.4 |
Suma, $ | 3.7 |
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Suponik, T.; Franke, D.M.; Nuckowski, P.M.; Matusiak, P.; Kowol, D.; Tora, B. Impact of Grinding of Printed Circuit Boards on the Efficiency of Metal Recovery by Means of Electrostatic Separation. Minerals 2021, 11, 281. https://doi.org/10.3390/min11030281
Suponik T, Franke DM, Nuckowski PM, Matusiak P, Kowol D, Tora B. Impact of Grinding of Printed Circuit Boards on the Efficiency of Metal Recovery by Means of Electrostatic Separation. Minerals. 2021; 11(3):281. https://doi.org/10.3390/min11030281
Chicago/Turabian StyleSuponik, Tomasz, Dawid M. Franke, Paweł M. Nuckowski, Piotr Matusiak, Daniel Kowol, and Barbara Tora. 2021. "Impact of Grinding of Printed Circuit Boards on the Efficiency of Metal Recovery by Means of Electrostatic Separation" Minerals 11, no. 3: 281. https://doi.org/10.3390/min11030281
APA StyleSuponik, T., Franke, D. M., Nuckowski, P. M., Matusiak, P., Kowol, D., & Tora, B. (2021). Impact of Grinding of Printed Circuit Boards on the Efficiency of Metal Recovery by Means of Electrostatic Separation. Minerals, 11(3), 281. https://doi.org/10.3390/min11030281