Development of an efficient e-waste recycling and beneficiation method into separable precious metals

¹ Engineering Department, Malawi University of Science and Technology, Thyolo, Malawi
² Department of Mechanical and Mechatronic Engineering, Cape Peninsula University of Technology, South Africa
³ Department of Energy Systems, Mzuzu University, Mzuzu, Malawi
⁴ Namibia University of Science and Technology, 13 Jackson Kaujeua Street, Windhoek, Namibia
⁵ Department of Material Science and Metallurgical Engineering, University of Pretoria, South Africa

^* Corresponding author: rnkhoma@gmail.com

Abstract

The issue of e-waste recycling is the uncharted territory in in most developing countries with a full potential to be a source of secondary resources. Every year there are tonnes of electronic materials with precious metals in them that lie in the landfills as there are no economically viable methods to extract them. Many people have attempted to recover precious metals from e-waste and the challenge is to come up with a method that is fast, clean (environmentally friendly), cheap and safe. The aim of the research was to recover precious metals that are of high value such as gold using hydrometallurgical methods. To achieve the faster reaction rate, the process involved heating H₂SO₄ to about 70±10°C and then washing with water after using a 1:1 solution of water to HNO₃ to get rid of other remaining metals. Afterwards, a 10:1 ratio of HCl to H₂O₂ was added in order to strip the components of gold. Precipitation of the gold solution was done using Na₂S₂O₅ and left for 4 hrs to settle. The final result, after precipitating and drying , showed that with the devised method, it is possible to recover gold at a shortest possible period of 4 days.