WASTE PRINTED CIRCUIT BOARDS are complex heterogeneous mixture consisting of organic material, metal and glass fiber, therefore, it is quite difficult for the recovery of valuable materials from WASTE PRINTED CIRCUIT BOARDS. In this study, WASTE PRINTED CIRCUIT BOARDS without electronic components (known as bare BOARDS) are submerged into dimethyl sulfoxide solvent at 170oC using refluxing process. Metallographic microscope shows that WASTE PRINTED CIRCUIT BOARDS produce the delamination after treated with dimethyl sulfoxide solvent for 15 min. When WASTE PRINTED CIRCUIT BOARDS are treated with dimethyl sulfoxide solvent for 30 min, the separation of WASTE PRINTED CIRCUIT BOARDS is complete to obtain metals and glass fibers. Moreover, the used dimethyl sulfoxide solvent is vaporized by the rotary decompression which obtains regenerative dimethyl sulfoxide and solid residues. Comparing two Fourier transform infrared spectroscopies, it is found that the regenerative dimethyl sulfoxide is the same as original dimethyl sulfoxide. Thermal analyses combined with Fourier transform infrared spectroscopy show that the solid residues are bromine epoxy resins. These findings suggest that this innovative technology offers an environmental friendly process with no pollution and high efficiency for separating valuable materials from WASTE PRINTED CIRCUIT BOARDS.

Background and Objectives: By improving technology at recent years, some new environmental problems created. Electronic WASTE is one of the important problems. Recycling of e-WASTEs is limited. Just some countries by using traditional methods are recycling e-WASTEs. Pyrometallurgy and hydrometallurgy are two recycling methods for e-WASTE. These traditional methods are expensive and non-ecofriendly. Bioleaching is a new and efficient method for e-WASTE recovery which by interacting microorganisms helps to metal recovery. In this article biorecovery of Cu, Al, Ni, Zn, Mn, Mg, Ba, Cr, and Fe from PRINTED CIRCUIT BOARDS using one-step bioleaching was studied. To this purpose computer PRINTED CIRCUIT BOARDS were fined and the particle size was in the range of 75-149 micron. Penicillium simplicissimum was adapted to 1% (w/v) of computer PRINTED CIRCUIT BOARDS. After adaptation and bioleaching process Cu, Al, Ni, Zn, Mn, Mg, Ba, Cr, and Fe were bioleached about 94%, 99/8%, 100%, 100%, 61%, 81%, 46%, 26%, and 100% respectively. This paper proved the great potential of the bio-hydrometallurgical route to recover base metals from electronic WASTEs using fungi.

Today, the use of automated optical inspection systems in the production of PRINTED CIRCUIT BOARDS to control solders, the presence of the right elements and their direction has become an essential tool for electronic companies. The PRINTED CIRCUIT board in this system is irradiated by several light sources and one or more high-definition cameras are used for imaging. Automated optical inspection system, using the recorded image and comparing the image information with the machine information, detects and specifies any type of error (defect) or suspicious areas. In this paper, using a camera mounted on a conveyor, we try to cover most of the common errors that occur on PRINTED CIRCUIT BOARDS at any stage of the production line. The traveling salesman algorithm is used to control the movement of the camera on the conveyor. To introduce the PRINTED CIRCUIT board to the system, a software has been designed that uses a CAD file to obtain the location and type of elements on the board. By selecting the optimal camera movement path, it detects errors due to the absence of elements, direction of elements, lack of soldering, cold soldering, excessive soldering, etc. in three stages of feature extraction, feature selection and decision making. The results show that the device is efficient in detecting glue error before installing the elements and detecting errors after tin bath.

It is greatly significant to separate precious metals from the WASTE PRINTED CIRCUIT BOARDS ((PCBS)) with appropriate methods for the resource recycling and environment protection. A combined physical beneficiation technology for the recovery of WASTE (PCBS) was investigated. WASTE (PCBS) were disassembled into substrates and slots firstly. WASTE PCB substrates were crushed to the size below 1 mm by a wet impact crushing approach. The double Rosin-Rammler functions were proposed to describe the particle size distribution characteristic of the substrates. The crushing products of the substrates were separated by a self-designed water-medium tapered column separation bed. The results indicate that the separation efficiency of 93.9% and metal recovery rate of 93.7% are obtained with a water discharge of 5.5 m3/h, feeding capacity of 250 g/min and inclination angle of 35o. WASTE PCB slots were crushed to the size range of 0.5-5 mm by a dry impact crushing approach and separated by an active pulsing air classifier. The separation results show that a separation efficiency of 92.4% and metal recovery rate of 96.2% are obtained with the airflow velocity of 2.90 m/s and pulsing frequency of 2.33 Hz. The mismatching components in the metal concentrate are relatively less with suitable operating conditions. Precious metals could be obtained by the further separation and purification of metal concentrates. The technology has great potential to be applied in the field of WASTE PCB recycling.

Recovery of gold and other valuable metals from electronic scrap involves a complex metallurgical flow sheet and requires state-of-the-art recovery technologies that are available in large-scale, integrated smelter and refinery operations. At the end of their use, electronic and other electrical product scrap offer an important recycling potential for the secondary supply of gold and silver into the market. With gold concentrations reaching 200-250 g/t for computer CIRCUIT BOARDS, this scrap is an ‘urban mine’ that is significantly richer in gold than the sources of the primary ores today. This paper gives methods of gold and silver recovery from PRINTED circular board. The methods of purification are given and they separate gold from the impurities (tin, copper and nickel). The obtained gold and silver have 99.99% quality.

In view of the rapidly increasing e-WASTE, bioleaching of metals from e-WASTE is an economical and ecologically conscientious option to address the issue of its disposal and/or recycling. Bioleaching of heavy metals by using bacteria of the Bacillus genus has been reported in many studies; however, the bioleaching potential of the Lysinibacillus genus is unexplored. In the present study, Lysinibacillus sp. SDG4 was isolated, identified, analysed and used for leaching toxic metals from e-WASTE PRINTED CIRCUIT BOARDS ((PCBS)). The bioleaching of metals was deciphered and analysed by using scanning electron microscopy (SEM) along with energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR) and inductively coupled plasma-optical emission spectrometry (ICP-OES). The presence of organic acids in the Lysinibacillus primary metabolites was established by FTIR analysis. The presence of functional groups like C–O and C–N in the transmittance band range of 1037.70 to 1658.78 cm-1 wavelength, C–H at 2746.63 and 2964.59 cm-1, O–H at 3412.08 cm-1 and RCO–OH at 582.50 cm-1 suggested the production of metal chelating functional groups by the bacterial strain. The heavy metal profile was determined using ICP-OES analysis. This revealed bioleaching of Al (99.74%), Zn (99.60 %), Cu (93.75%) and Fe (59.24%) in 30 days with a PCB concentration of 1 gm/ml by Lysinibacillus sp. SDG4.  These findings confirmed the display of morphological changes by accumulation of metals by Lysinibacillus sp. SDG4 using SEM-EDX analysis. Thus, the study exhibited the potential of the Lysinibacillus genus in bioleaching metals from e-WASTE.