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The implications of physical conditions of the feedwell on the rheological properties of synthetic copper tailings, flocculated in seawater, were analysed. The mixing intensity of flocculation was related to the structural characteristics of the aggregates, and the outcomes were linked to the yield stress of the pulp sediments. Tailings settling assays were conducted by using a 30 mm turbine type stirrer with an in-situ aggregate size characterisation. The structural characteristics of the aggregates were determined by using the focused beam reflectance measurement (FBRM). After a mixing time between the pulp and the flocculant, the sample was allowed to settle for 2.5 h, where the variation of the sediment height was minimal. The sediment was gently removed and subjected to rheological characterisation. The yield stress was measured on an Anton Paar MCR 102 rheometer (ANAMIN Group, Santiago, Chile), with a vane-in-cup configuration. The mixing intensity was related to the characteristics of the aggregates, and the outcomes were linked to the yield stress of the flocculated pulp sediments. More aggressive hydrodynamics deteriorated the structure of the aggregates, promoting the reduction of both its size and the fractal dimension. This brought direct consequences on the rheological properties of the sediments: at higher mixing level, the yield stress was lower. The explanation lies in the structural changes of the aggregates, where at a fixed mixing rate, the yield stress presented a seemingly exponential increase over the fractal dimension. Additionally, correlations were found between the rheological properties with settling rate and aggregate size.
Matías Jeldres; Eder C. Piceros; Norman Toro; David Torres; Pedro Robles; Williams H. Leiva; Ricardo I. Jeldres; Jeldres. Copper Tailing Flocculation in Seawater: Relating the Yield Stress with Fractal Aggregates at Varied Mixing Conditions. Metals 2019, 9, 1295 .
AMA StyleMatías Jeldres, Eder C. Piceros, Norman Toro, David Torres, Pedro Robles, Williams H. Leiva, Ricardo I. Jeldres, Jeldres. Copper Tailing Flocculation in Seawater: Relating the Yield Stress with Fractal Aggregates at Varied Mixing Conditions. Metals. 2019; 9 (12):1295.
Chicago/Turabian StyleMatías Jeldres; Eder C. Piceros; Norman Toro; David Torres; Pedro Robles; Williams H. Leiva; Ricardo I. Jeldres; Jeldres. 2019. "Copper Tailing Flocculation in Seawater: Relating the Yield Stress with Fractal Aggregates at Varied Mixing Conditions." Metals 9, no. 12: 1295.
In this study, the viscoelastic properties of quartz and kaolin suspensions in seawater were analysed considering two distinct conditions: pH 8 and 10.7. Creep and oscillatory sweep tests provided the rheological parameters. An Anton Paar MCR 102 rheometer (ANAMIN Group, Santiago, Chile) was used with a vane-in-cup configuration, and the data were processed with RheoCompassTM Light software (ANAMIN Group, Santiago, Chile). The outcomes were associated with the formation of solid species principally composed of magnesium precipitates. The magnesium in solution reduced in the presence of quartz (68 wt %), from 1380 to 1280 mg/L. Since the difference was not large regarding the solid-free seawater, the disposition of solid complexes at pH 10.7 was expected to be similar. The jump in pH caused both yield stress and viscoelastic moduli to drop, suggesting that the solid precipitates diminished the strength of the particle networks that made up the suspension. For the kaolin slurries (37 wt %), the yield stress raised when the pH increased, but unlike quartz, there was significant adsorption of magnesium cations. In fact, the concentration of magnesium in solution fell from 1380 to 658 mg/L. Dynamic oscillatory assays revealed structural changes in both pulps; in particular, the phase angle was greater at pH 8 than at pH 10.7, which indicates that at more alkaline conditions, the suspension exhibits a more solid-like character.
Matías Jeldres; Eder Piceros; Pedro A. Robles; Norman Toro; Ricardo I. Jeldres. Viscoelasticity of Quartz and Kaolin Slurries in Seawater: Importance of Magnesium Precipitates. Metals 2019, 9, 1120 .
AMA StyleMatías Jeldres, Eder Piceros, Pedro A. Robles, Norman Toro, Ricardo I. Jeldres. Viscoelasticity of Quartz and Kaolin Slurries in Seawater: Importance of Magnesium Precipitates. Metals. 2019; 9 (10):1120.
Chicago/Turabian StyleMatías Jeldres; Eder Piceros; Pedro A. Robles; Norman Toro; Ricardo I. Jeldres. 2019. "Viscoelasticity of Quartz and Kaolin Slurries in Seawater: Importance of Magnesium Precipitates." Metals 9, no. 10: 1120.