Synergistic coagulation effect of the cationic coagulant and anionic flocculant on fluorite tailings

The efficient dewatering and thickening of tailings is the first step in the backfilling process and an essential prerequisite for high-quality backfilling. In order to clarify the supernatant of fluorite tailings slurry, the combination of cationic coagulant and anionic flocculant was proposed to increase the sedimentation efficiency and improve the sedimentation behavior of the tailings. In this study, the flocculation and sedimen-tation performance of fluorite tailings were investigated through static sedimentation experiments and dynamic sedimentation experiments. The results show that fine mont-morillonite particles with strong negative charges were the key reason for the turbidity of fluorite tailings slurry. And the synergistic effect of cationic coagulant combined with anionic flocculant significantly reduced the suspended solid content in the supernatant of fluorite tailings slurry. The suspended solid content in the supernatant decreased to 186 mg/L with the flocculant dosage of 10 g/t and the coagulant dosage of 20 g/t, which meets the wastewater discharge requirements. Additionally, a physical model of the tailings coagulation process was proposed. The coagulation process can be divided into the initial stage, the coagulation stage, the flocculation stage, and the sedimentation stage. The research results could provide insights into the development of flocculation and sedimentation technologies for fluorite tailings. (c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).