Optimization of Tailings Paste Preparation for Deep-Cone Thickeners Prone to Rake Blockage: From Particle Classification to Tailings Reconstitution

To address the high risk of rake blockage in deep-cone thickeners and the difficulty in optimizing backfill performance during paste preparation from full tailings, a paste preparation method based on particle classification, tailings dewatering, and secondary remixing and reconstruction was proposed. Sedimentation thickening tests, flowability tests, and strength tests were conducted to systematically investigate the dewatering characteristics of tailings, the flowability of backfill slurry, and the strength development of backfill. The results showed that flocculation sedimentation significantly improved the thickening efficiency of fine tailings. With increasing coarse-tailings proportion, the flowability of the slurry was enhanced, and the allowable transportable solids concentration gradually increased. The strength of the backfill was jointly affected by tailings gradation, solids concentration, and binder-to-tailings ratio, among which the binder-to-tailings ratio was the dominant factor, while an optimum tailings gradation existed. Based on the experimental results, a paste backfilling process suitable for the target mine was proposed. By separating the coarse fraction from the deep-cone thickening stage and subsequently remixing it with the thickened fine tailings, the proposed process provides a process-level basis for reducing the potential risk of rake blockage while maintaining satisfactory backfill performance. The findings provide a reference for the design of paste backfilling systems in mines utilizing full tailings.