Utilization of magnetic and electrostatic separation in the recycling of printed circuit boards scrap

To discover the influence of separation technologies for PCBs on the preparation, characterization and application of pyrolytic carbon, two kinds of nonmetal fraction from magnetic and electrostatic separation were chosen as the precursors.

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Recovery of Metals from Printed Circuit Boards By Means of Electrostatic Separation

Management Systems in Production Engineering ◽

10.2478/mspe-2020-0031 ◽

2020 ◽

Vol 28 (4) ◽

pp. 213-219

Author(s):

Dawid Franke ◽

Tomasz Suponik ◽

Paweł M. Nuckowski ◽

Klaudiusz Gołombek ◽

Kamila Hyra

Keyword(s):

Waste Management ◽

Printed Circuit Boards ◽

Printed Circuit Board ◽

New Technologies ◽

Negative Impact ◽

Electronic Waste ◽

Circuit Board ◽

Circuit Boards ◽

Electrostatic Separation ◽

Printed Circuit

AbstractWithout the use of appropriate recycling technologies, the growing amount of electronic waste in the world can be a threat to the development of new technologies, and in the case of improper waste management, may have a negative impact on the environment. This is due to the fact that this waste contains large amounts of valuable metals and toxic polymers. Therefore, it should be recycled in accordance with the assumptions of the circular economy. The methods of mechanical recovery of metals from electronic waste, including printed circuits, may be widely used in the future by waste management companies as well as metal production and processing companies. That is why, a well-known and easily applicable electrostatic separation (ES) method was used to recover metals from printed circuit boards. The grain class of 0.32 - 0.10 mm, obtained after grinding the boards, was fed to a separator. Feed and separation products were analyzed by means of ICP-AES, SEM/EDS and XRD. The concentrate yield obtained after electrostatic separation amounted to 32.3% of the feed. Its density was 11.1 g/cc. Out of the 91.44% elements identified in the concentrate, over 90% were metals. XRD, SEM observations and EDS analysis confirmed the presence of non-metallic materials in the concentrate. This relatively high content of impurities indicates the need to grind printed circuit board into grain classes smaller than 0.32-0.10 mm.

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Simulation of Corona Electrostatic Separator for End-of-Life Management in Printed Circuit Boards

10.1115/detc2021-71447 ◽

2021 ◽

Author(s):

Trunal Patil ◽

Lara Rebaioli ◽

Irene Fassi

Keyword(s):

End Of Life ◽

Process Parameters ◽

Printed Circuit Boards ◽

Separation Process ◽

Circuit Boards ◽

Electrostatic Separation ◽

Printed Circuit ◽

Life Management ◽

Electrostatic Separator ◽

Particles Trajectories

Abstract Printed circuit boards (PCBs) are made of several materials, including platinum, gold, silver, and rare earth elements, which are very valuable from a circular economy perspective. The PCB end of life management starts with the component removal, then the PCBs are shredded into small particles. Eventually, different separation methods are applied to the pulverized material to separate metals and non-metals. The corona electrostatic separation is one of the methods that can be used for this purpose since it is able to separate the conductive and non-conductive materials. However, the lack of knowledge to set the process parameters may affect the efficiency of the corona electrostatic separation process, ultimately resulting in the loss of valuable materials. The simulation of particle trajectory can be very helpful to identify the effective process parameters of the separation process. Thus, in this study, a simulation model to predict the particles trajectories in a belt type corona electrostatic separator is developed with the help of COMSOL Multiphysics and MATLAB software. The model simulates the particle behavior taking into account the electrostatic, gravitational, centrifugal, electric image, and air drag forces. Moreover, the predicted particles trajectories are used to analyze the effects of the roll electrode voltage, angular velocity of roll electrode, and size of the particles on the separation process.

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Impact of Grinding of Printed Circuit Boards on the Efficiency of Metal Recovery by Means of Electrostatic Separation

Minerals ◽

10.3390/min11030281 ◽

2021 ◽

Vol 11 (3) ◽

pp. 281

Author(s):

Tomasz Suponik ◽

Dawid M. Franke ◽

Paweł M. Nuckowski ◽

Piotr Matusiak ◽

Daniel Kowol ◽

...

Keyword(s):

Cryogenic Temperature ◽

Printed Circuit Boards ◽

Raw Materials ◽

Microscopic Analysis ◽

Sieve Analysis ◽

Circuit Boards ◽

Electrostatic Separation ◽

Printed Circuit ◽

Valuable Metals ◽

The Impact

This paper analyses the impact of the method of grinding printed circuit boards (PCBs) in a knife mill on the efficiency and purity of products obtained during electrostatic separation. The separated metals and plastics and ceramics can be used as secondary raw materials. This is in line with the principle of circular economy. Three different screen perforations were used in the mill to obtain different sizes of ground grains. Moreover, the effect of cooling the feed to cryogenic temperature on the final products of separation was investigated. The level of contamination of the concentrate, intermediate, and waste obtained as a result of the application of fixed, determined electrostatic separation parameters was assessed using ICP-AES, SEM–EDS, XRD, and microscopic analysis as well as specific density. The yields of grain classes obtained from grinding in a knife mill were tested through sieve analysis and by using a particle size analyser. The test results indicate that using a knife mill with a 1 mm screen perforation along with cooling the feed to cryogenic temperature significantly improves the efficiency of the process. The grinding products were characterised by the highest release level of the useful substance—metals in the free state. The purity of the concentrate and waste obtained from electrostatic separation was satisfactory, and the content of the intermediate, in which conglomerates of solid metal–plastic connections were present, was very low. The yield of concentrate and waste amounted to 26.2% and 71.0%, respectively. Their purity, reflected in the content of the identified metals (valuable metals), was at the level of 93.3% and 0.5%, respectively. In order to achieve effective recovery of metals from PCBs by means of electrostatic separation, one should strive to obtain a feed composed of grains <1000 μm and, optimally, <800 μm.

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