Rheological Characterization of Mineral Slurries Based on the Principle of Maximum Entropy †

The rheological characterization of mineral slurries is a complex task, especially in the presence of coarse particles with high specific gravity, such as hematite. In laboratory rotational rheometers (LRRs), entrance effects, particle settling, and Taylor vortices can jeopardize the accuracy of the results. This paper presents a new methodology for the rheological characterization of mineral slurries in tubular devices and the Principle of Maximum Entropy (PME) supports this new approach. Iron ore slurries were prepared at mass concentrations of 36.8 % and 43.6 % solids and subjected to rheological characterization in LRR and a pumping loop tubular device (PLTD). The results from LRR revealed shear-thickening behavior for the slurries; whereas the results from PLTD, associated with entropic equations for the friction factor and shear rate, revealed shear-thinning behavior (at low shear rates) and shear-thickening behavior (at high rates). The results from LRR plus PLTD were plotted in a single rheogram, and curve fitting was accomplished by the power law model (R2 = 0.995), indicating an overall shear-thickening behavior. PME proved to be capable of supporting the rheological characterization of mineral slurries at shear rates above 1500 s-1 in PLTD, complementing the results obtained by LRR. Shear Stress (Pa) 25 20 15 10 5 0 Rotational Rheometer Tubular Device Cm/m= 43.6% y= 4.279E-4x1.409 R2 = 0.995 0 500 1000 1500 Shear Rate (s-1) 2000 2500 Shear Stress (Pa) 25 20 15 10 5 0 Rotational Rheometer Tubular Device Cm/m = 36.8% y = (3.997E -4)x1.411 R2 = 0.995 0 500 1000 1500 2000 2500 Shear Rate (s-1)