Publication: Recovery of copper from waste printed circuit board by ultrasonic assisted separation
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Date
2024-07
Authors
Richard, Mazunzo Dikamdima
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Abstract
Recycling of waste printed circuit boards (WPCBs) normally result in the production of toxic substances and fumes that are polluting to the environment. Most of the recycling techniques use chemicals that can have negative impacts to the environment. It was important to develop a recycling technique that would be non-destructive and at the same time addressing the environmental concerns. In this work, a novel technology was developed in which ultrasonic pretreatment was used to enhance the separation of metals and non-metals in water. Then, a flotation process
with waste cooking oil (WCO) was used to recover copper. In this technology, no chemicals were used, and it is, therefore, considered a pollution-free process since no toxic effluent was discharged. Furthermore, WCO characterization showed that it has several organic compounds. The most dominant compound is oleic acid, which is a collector itself. The WPCBs were crushed and pretreated with ultrasound in an ultrasonic bath. The particles were then separated in water in a customised separation tank. Five factors that could influence copper recovery were studied. It was established that particle size and ultrasonication time were the most significant factors in the ultrasonic pretreatment. Particle size and ultrasonication time were linearly significant. Mass, bubbles and ultrasonication frequency were linearly insignificant. However, there were interactions among these factors. The maximum copper recovery obtained was 93.95%. The results were obtained with the following optimized parameters: a particle size fraction of (-212+106) μm, 20g of sample, and an ultrasonic pretreatment time of 69.3 minutes. The WCO was simply filtered to remove solid impurities. It has been shown that when used as a collector, WCO produced better results in terms of flotation rate than when gasoline was used. At a collector dosage of 0.1 mL/g of WPCB sample, a flotation rate of copper of 0.00179 g/ml was archived.