Depression of Pyrite in Seawater Flotation by Guar Gum

The application of guar gum for pyrite depression in seawater flotation was assessed through microflotation tests, Focused Beam Reflectance Measurements (FBRM), and Particle Vision Measurements (PVM). Potassium amyl xanthate (PAX) and methyl isobutyl carbinol (MIBC) were used as collector and frother, respectively. Chemical species on the pyrite surface were characterized by Fourier-transform infrared spectroscopy (FTIR) spectroscopy. The microflotation tests were performed at pH 8, which is the pH at the copper sulfide processing plants that operate with seawater. Pyrite flotation recovery was correlated with FBRM and PVM characterization to delineate the pyrite depression mechanisms by the guar gum. The high flotation recovery of pyrite with PAX was significantly lowered by guar gum, indicating that this polysaccharide could be used as an effective depressant in flotation with sea water. FTIR analysis showed that PAX and guar gum co-adsorbed on the pyrite surface, but the highly hydrophilic nature of the guar gum embedded the hydrophobicity due to the PAX. FBRM and PVM revealed that the guar gum promoted the formation of flocs whose size depended on the addition of guar gum and PAX. It is proposed that the highest pyrite depression occurred not only because of the hydrophilicity induced by the guar gum, but also due to the formation of large flocs, which could not be transported by the bubbles to the froth phase. Furthermore, it is shown that an overdose of guar gum hindered the depression effect due to redispersion of the flocs

Dynamic moduli of flocculated kaolinite sediments: effect of salinity, flocculant dose, and settling time

Oscillatory rheological assays are used to determine the viscoelastic properties of flocculated kaolinite sediments over a range of sodium chloride concentration, flocculant dose, and settling time. The plunger method is used to promote efficient mixing between flocculant, particles, and electrolytes, ensuring the least amount of disturbance in the system. The suspensions are prepared at natural pH, varying salt concentration and flocculant dose, and then allowed to settle for a pre-set time. The sediment is then subjected to oscillatory rheological tests under small amplitude oscillatory shear (SAOS) and large amplitude oscillatory shear (LAOS) regimes. It is very remarkable that the viscoelastic moduli respond differently depending on the variable being examined; on the one hand, the salinity changes the internal structure of the floc network conforming the sediment by adopting liquid-like characteristics as salinity increases, on the other hand, different flocculant doses and settling times lead to unaltered floc network architectures

Analysis of Silica Pulp Viscoelasticity in Saline Media: The Effect of Cation Size

The effect of alkali metal chlorides on the viscoelastic behavior and yielding properties of silica suspensions was studied through creep-recovery and dynamic oscillatory tests with stress control. Then, the viscoelasticity of the pulps was correlated with the silica zeta potential, aggregate size, and the percentage of cations adsorbed on the surface of the ore. The results indicate that larger cations are more prone to adhere to the silica surface, which increases the number of ionic bonds that bind the particles. This generates stronger particle networks and a greater agglomeration of particles, especially those smaller than 10 µm. As the size of the bare cations increases, the rheological response provides higher values of yield stress, complex viscosity, and viscoelastic moduli, but in turn, pulps undergo minor deformations under the application of stress. Dynamic oscillatory tests suggest structural changes, with the phase angle following the inverse relationship with the bare cation size, indicating that the liquid-like character of the pulps increases as the size of the cations increases