Hydrometallurgical processes for heavy metals recovery from industrial sludges

Abstract

Hydrometallurgical approaches have been successfully employed for metal separation and recovery from various types of waste materials. Therefore, hydrometallurgy is a promising technology for metal recovery and the removal of potentially toxic heavy metals found in industrial sludge. However, a comprehensive review that focuses on the heavy metal recovery from industrial sludge using hydrometallurgical approaches has not been conducted in the recent past. The present review discusses the capacity of hydrometallurgical techniques in recovering heavy metals sourced from different types of industrial sludges, highlighting recent scientific findings. Hydrometallurgical approaches primarily consist of three process stages: metal dissolution, concentration and purification, and metal recovery. The chemical characteristics of industrial sludge, including the type, concentration and speciation of heavy metals, directly impact selection of the best recovery method. Solvent extraction, ion-exchange, and adsorption are the major techniques employed in concentration and purification, whereas electrodeposition and precipitation are the main methods used in metals recovery. Future research should focus on the development of more efficient and environmentally-friendly methods for metal dissolution from industrial sludges contaminated with multiple metals, while increasing selectivity and energy use efficiency in the concentration and purification, and recovery steps.

Graphical abstract

Keywords:

• Industrial waste
• resource recovery
• acid leaching

Additional information

Funding

The authors would like to acknowledge the Research Council, University of Sri Jayewardenepura, Sri Lanka, for providing financial support (Grant No. ASP/01/RE/SCI/2017/82) and the Ecosphere Resilience Research Centre, University of Sri Jayewardenepura, Sri Lanka, for providing the working environment. This work was supported by Hydrogen Energy Innovation Technology Development Program of the National Research Foundation of Korea (NRF) funded by the Korean government (Ministry of Science and ICT(MSIT)) (NRF-2019M3E6A1064197) and Korea University Grant.