Effects of alkali-salt fusion process on recovery of amphoteric metals from waste printed circuit boards

Abstract

In this study, crushed metal enrichment (CME) originated from waste printed circuit boards was treated by a novel oxidizing alkali-salt fusion process to separate and recover metal values. The fusion system consists of CME, alkaline medium and oxidant. Based on former studies, mixture of NaOH and Na₂CO₃ was selected as alkaline medium, while NaNO₃ as the oxidant. Parameters and factors of the fusion process were studied systematically, and the optimized conditions were determined as CME/Na₂CO₃/NaOH/NaNO₃ mass ratio of 1:1:3:3, fusion temperature of 600°C, and fusion time of 40 min. Under these conditions, 84.55% of Sn, 73.97% of Pb, 95.22% of Al and 78.87% of Zn were transferred into solution, while over 99.51% of Cu and all precious metals were enriched in the residue.

Keywords

Alkali-salt fusion system Waste printed circuit board Amphoteric metal Conversion

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