Effect of pyro-processing conditions on impurity removal and precious metal enrichment in waste printed circuit board (WPCB) recycling process

Abstract

The combinatorial effects of slag composition and O-2-blowing conditions on silicon (Si) and iron (Fe) removal as well as gold (Au) and silver (Ag) enrichment from waste printed circuit boards (WPCBs) were investigated to optimize pyrometallurgical WPCBs recycling process. Regardless of the experimental conditions, the removal rate for Si and Fe was approximately 100%, except in slag-free operation. The Si removal rate was generally higher than the Fe removal rate at a given reaction time irrespective of experimental variables because the O-2 affinity of Si is higher than that of Fe in molten copper, thermodynamically. The removal rate of impurities was clearly dependent on blowing conditions and slag composition, and a combinatorial operation of bottom-blowing and highly fluid slag favored the efficient removal of impurities. The maximum enrichment ratio of Au and Ag (C-Au,Ag(Max)) was about 10% and the possession rates of Au and Ag, R-Au,R-Ag at C(Au,Ag)(Max & nbsp