COMBINED MECHANICAL BIO-HYDROMETALLURGICAL RECYCLING PROCESS OF PRINTED CIRCUIT BOARDS IN BRAZIL

Abstract

Precious metal content is much higher in electronic waste than in most worldwide mines, and therefore recycling is encouraged and mostly performed by hydrometallurgical and pyrometallurgical processes. This paper addresses a combined mechanical bio-hydrometallurgical recycling process for extracting gold, copper and iron from printed circuit boards as a less expensive technology feasible for the Brazilian context. Metal recovery was carried out by combining physical, chemical and biological processes. The combined process proved to be technically viable; the microbiological route using adapted bacteria Acidithiobacillus ferrooxidans-LR is also eco-friendly. Mechanical processes recovered 97% of the iron by magnetic separation, the bioleaching extracted 99% of the copper, and 86% of the gold was recovered during the last stage of cyanidation.