Copper Recovery From Waste Printed Circuit Boards And The Correlation Of Cu Pb Zn By Ionic Liquid

Abstract

Waste printed circuit boards (WPCBs) contain not only harmful materials but also many valuable resources, especially metals, which attracts more and more attention from the public. In this study, a sulfonic acid functionalized ionic liquid ([BSO3HPy]OTf) was used to recycle copper from WPCBs. Zinc and lead, represented as typical heavy metals, were chosen to study the leaching behavior and their relation to copper. Five factors such as particle size, ionic liquid (IL) concentration, H2O2 dose, solid to IL ratio and temperature were investigated in detail. The results showed that copper leaching rate was high, up to 99.77%, and zinc leaching rate reached the highest value of 74.88% under the optimum conditions. Lead cannot be leached effectively and the leaching rate was mostly low than 10%, which indirectly indicated that [BSO3HPy]OTf has a good selectivity to lead. Besides, the interaction of copper, lead and zinc was characterized macroscopically by means of statistical methods. The Spearman correlation analysis showed that copper and zinc had a highly positive correlation. Lead had little relation to copper, which to some extent indicated that the effect of zinc on copper leaching behavior was bigger than that of lead. 56F. LI, M. CHEN compared to 39.8 million metric tons in 2013, reaching to 41.8 million metric tons. However, the recycle of global e-waste is less than one in six in 2014 [3].Waste printed circuit boards (WPCBs) are the basic components of almost all WEEE, e.g., household appliances, personal computers and mobile phones. Thus, the recovery of WEEE is more inclined to the recycling of WPCBs [4]. WPCBs consist of environmentally poisonous materials such as persistence organic pollutants (POPs) and heavy metals (Pb, Cd, Cr). If not treated appropriately, it could badly threaten environment and human health [5]. In other sides, electronic wastes as the effective secondary resources contain many valuable substances. For example, a typical WPCBs constitute by more than 70 wt. % non-metal (i.e., plastic, resins, glass fibers) and metals (copper 16 wt. %, iron 3 wt. %, nickel 2 wt. %, silver 0.05 wt. %, gold 0.03 wt. % and palladium 0.01 wt. %) [6]. Generally copper content in WPCBs is much higher than that of other metals, and the market demand for copper increases year and year [7], which makes copper an important economic driver. Therefore, the recycling of WPCBs is an urgent environmental problem to be solved not only from the perspective of environmental protection but also the resource reuse.Many researchers have studied the recycling of WPCBs, including the mechanical--physical process [8,9], pyrometallurgy [10], hydrometallurgy [11,12] and biometallurgy [13,14]. The mechanical-physical process is the most widely used for the industrial treatment but it is usually as the preparation due to the limitation of metal alloy separation. The development of pyrometallurgy, a traditional technology for recycling precious metals from WPCBs, is restricted by the emission of harmful gases and highenergy con...