• Thickened tailings exhibit pronounced nonhomogeneity in concentration, coarse particle content, and pore structure, with concentration and coarse particle proportion increasing toward lower slurry heights.
• Static yield stress (τB) of thickened tailings is 5.3–61.3 times higher than that of freshly mixed slurry, highlighting severe flowability challenges in thickening equipment.
• The coefficient of variation (CV) of slurry porosity is introduced as a quantitative indicator; lower CV values correspond to lower static yield stress, enabling predictive control.
• Field validation at an iron ore mine in China confirms that the CV-based approach can mitigate slurry hardening and rake blockages in silos and thickeners.