Residue sampling and characterization

This chapter provides a comprehensive review of techniques, instruments, and methods suitable for mine residue sampling and characterization, using the potential recovery of critical raw materials (CRMs) from bauxite residues as an example. The sampling methods address diverse strategies for assessing the suitability of CRMs recovery, including screening, detailed characterization, determination of acid rock drainage generation and wastewater, and the implementation of a geometallurgical approach. The methods for characterizing mine residues are a selection of geochemical, mineralogical, and other techniques that can be used either in field environments (e.g., portable X-ray fluorescence, infrared spectroscopy) or in the laboratory (e.g., inductively coupled plasma-based techniques, scanning electron microscopy) to study the main properties of the waste material. Other techniques used for the remote characterization, such as earth observation are also addressed. Approaches for data analytics and the impact of digitalization in the characterization of mine residues are briefly discussed. Overall, this chapter aims to help practitioners and researchers to implement better practices in the sampling and characterization for the revalorization of mine residues.