Date

2022-8

Author

Aktaş, Berke Beste

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The gradual depletion of high-grade ores force mining operations to process ores to finer particles to extract valuable minerals. With the increased amount of fine particles and, in some cases, high clay mineral content presence, complex rheological behaviors in phases including suspensions, such as high viscosity and high yield stress have been observed, causing a decrease in the performance of certain mineral processing operations. Through the study, rheological characteristics of ore tailings slurries with respect to the mineralogy and with special emphasis on the presence of clay minerals were investigated for backfill purposes of tailings from mineral processing plants. Also, this study aims to identify the influence of clay presence, on the flow behavior of ore tailings slurries, as a key information for slurry involving phases in downstream processes. Pure mineral suspensions and tailings samples were investigated in terms of surface charge properties to establish a rheological classification. In addition to surface charge property experiments, the rheological properties of the tailings samples with greater and less extent of clay minerals were examined to enable the real simulations of rheological properties of clay minerals in complex multi-component ore systems where different clay particles are locked in valuable mineral particles. The tailings samples were examined to identify their viscosity and yield stress values at different pulp conditions. The rheological data produced were evaluated using “Bingham Plastic” and “Casson” models. The significant findings were obtained thanks to rheological measurements. First of all, regardless of the vein of the tailings samples, the samples showed thixotropic behavior. Secondly, it was obtained that solid content plays an important role in viscosity regardless of which veins the tailings samples were sourced. The small amount of increase in the solid content caused a significant decrease in the flow by increasing viscosity. In addition to these findings, it was revealed that the mineralogical characteristics have a significant effect on the rheological behavior of tailings slurries. In this context, the ore tailings sample from the clayey vein of the deposit showed higher viscosity than that of the normal vein of the same deposit despite similar solid content. The higher values of surface charges caused the more dispersed state whereas the particles with relatively lower values of surface charges were prone to interparticle interactions and agglomeration in suspensions. As a result, this would result in suspensions of higher viscosity and yield stress than in the dispersed state. To conclude, the transportation of “clayey” tailings was observed to be more challenging. Therefore, it becomes more critical to optimize rheological behavior of ore tailings slurries by arranging solid content especially for “clayey” tailings. In other words, the mineralogical characteristics of tailings slurries, and the processing conditions are critical for the transportation of the tailings from the minerals processing plant for backfill purposes. Therefore, the real simulation and the optimization of the rheological behavior of ore tailings slurries are of great importance so that the problems encountered during the transportation of tailings can be eliminated, and the desired processing plant conditions with high command can be provided.

Subject Keywords

Rheology, Yield Stress, Viscosity, Surface Charge, Clay Minerals

URI

https://hdl.handle.net/11511/98775

Collections

Graduate School of Natural and Applied Sciences, Thesis