Quantifying the platy morphology of gangue minerals with X-ray diffraction: A talc case study

Understanding the platy morphology of gangue minerals like talc is crucial for improving flotation operation efficiency, which is essential for beneficiation of low-grade copper ores. A practical method for quantifying the platy morphology of talcs using X-ray diffraction patterns is presented. The platy morphologies of talcs from various geological origins were quantified using an XRD morphology index (MI) that considers the aspect ratio as measured by the relative intensities of (004) and (020) Bragg reflections. Comparisons with the XRD preferred orientation (PO) correction, and the inverse aspect ratio (AR) from X-ray micro-computed tomography (micro-CT) and scanning electron microscopy (SEM), were conducted to validate the XRD-determined MI. There was a moderate correlation of 53.1 % between MI and the SEM-determined 2D inverse AR. The inverse AR results of the micro-CT did not correlate with that from the SEM. However, a strong correlation was observed between MI and XRD-determined PO correction and micro-CT-determined 3D inverse AR, with R² values of 90.3 % and 97.1 %, respectively. The results indicate that XRD, assuming adequate sample preparation, is a promising, feasible and rapid way to quantify the platy morphology of talc, whereas 2D SEM cannot quantify platiness due to the limitations of 2D projection and analysis of non-spherical particles.