Kamalesh Kumar Singh

Title : Hydrometallurgical recovery of copper and gold from waste Printed circuit boards

Abstract:

Due to increasing trends of electronic waste specially the ICT related gadgets, their green recycling is still a greater challenge. This article presents a two-stage, eco-friendly hydrometallurgical route for the recovery of gold from the delaminated metallic layers of waste mobile phone Printed Circuit Boards. Initially, the printed circuit boards of waste mobile phone are cleaned with acetone. The attached components are removed by loosening the solders. The PCBs free from attached components are then downsized (1x1 cm²) and treated with an organic solvent dimethylacetamide. The organic solution enters the organic PCBs and act for the separation of metallic fraction from non-metallic glass fiber. In the first stage, liberated metallic sheets are used for the selective dissolution of copper in an aqueous leaching reagent. Influence of various parameters such as type of leaching reagent, the concentration of the solution, temperature, time and pulp density are optimized for the effective leaching of almost all copper. Results have shown that 3M nitric acid is a suitable reagent for copper leaching at room temperature. Gold is not leached and due to its chemical features, it remained there in solid residue. In the second stage, the separated residue is used for the recovery of gold by using sulphuric acid with a combination of halide salt. The halide leaching using in situ generated Cl₂ or Br₂ oxidant improve the leaching efficiency of the precious metal gold. Recovery of gold is at the optimized parameters is found more than 90 percent. The proposed process is economical and robust in favour of sustainable recycling of waste printed circuit boards.

Audience Take Away Notes:

• The recyclers of electronic waste can adopt this innovative process. It can help to design a new process of recycling of waste PCBs
• It will help the audience to learn a new process of hydrometallurgical metal extraction
• The academician and faculty members can expand their research and teaching skills by adding the outcome of this research in their labs and classrooms

Biography:

Dr. Kamalesh Kumar Singh studied Metallurgical Engineering at BIT Sindri at UG level 1994 and then did PhD at the Ranchi University, India in 2008. He then joined the department of Metallurgical Engineering at the Indian Institute of Technology Banaras Hindu University, Varanasi, India. He introduced a course in Management and recycling of electronic waste at same institute . He has published more than 50 research articles in reputed research journals.