Study of the thickening and filtration of sulphide flotation tailings

This study investigates the thickening and filtration processes of sulphide flotation tailings using a laboratory-scale high-performance thickener with a diameter of 99 mm and a pilot-scale thickener with a diameter of 190 mm. Filtration of these tailings was tested using a laboratory filter press. Flocculants from the Nalco, Granfloc, and Magnafloc brands were evaluated. The sulphide flotation tailings utilized in the research had a density ranging from 1221 to 1234 kg/m3, with a solid phase density of 2710 to 2750 kg/m3. The tailings contained 28 to 29 % solids by weight. The sedimentation process and discharge purity were analyzed, revealing that the optimal flocculant dosage for achieving the required discharge purity was approximately 100 g/t using Granfloc 1435-1. Dynamic tests have shown that the maximum solid content achievable for the tailings slurry in the pilot-scale thickener (PT modification) was 66.3–66.4 % by weight. Rheological analysis was conducted using a HAAKE THERMO VT550 electronic rotational viscometer with a four-blade OK 600 rotor. The measured shear stress values ranged from 81 to 84 Pa, indicating that the tailings did not exhibit paste-like behavior. The specific performance under the optimal conditions was found to be 0.3 t/(m2·h), with a solids content of 13.8 % in the feed. Filtration tests were performed using a membrane filter press with a filtration area of 0.27 m2. The results have demonstrated that the tailings could be filtered at a specific filtration rate of 32.6 kg/(m2·h), achieving a residual cake moisture content of 16.3 %. Based on these findings, technical recommendations are proposed for the thickening and filtration of sulphide flotation tailings.