Effect of particle size, blend ratio and some selective bio-additives on rheological behaviour of high-concentration iron ore slurry

摘要

The influence of particle size, blend ratio and some selective bio-additives on the rheological behaviour of an Indian iron ore sample in a slurry concentration range of 60-75% by mass was evaluated. The rheological parameters were measured using a high-precision ThermoFisher Scientific HAAKE? RheoStress? 1 Rheometer. The iron ore slurry samples indicated non-Newtonian flow behaviour and fitted quite well with the Bingham plastic model in the studied range of concentrations. The specific multimodal iron ore samples with a broad size distribution indicated a substantial reduction in slurry viscosity, yield stress and improved solids loading compared to monomodal ones. The reduction in apparent viscosity at a given shear rate for the specific iron ore slurry sample was correlated to a distribution modulus (Ψ) derived from the Farris theory.The application of small dosages (0.8-1% w/w of total solids) of two selective bio-additives extracted from Indian spinach (Basella alba) and Bellyache bush (Jatropha gossypifolia Linn) further reduced the Bingham viscosity and yield stress values through surface modification at higher solids loading. The increase in yield stress values with an increase in solids concentration was attributed to the formation of loosely packed floes and immobilisation of water within them, thus increasing particle-particle and particle-fluid friction. The bio-additives may be able to improve the fluid mobility among the particles, thus reducing the internal friction constituting the floes and facilitating the slurry flow with the application of a reasonably lesser shearing force. The study reveals that the blending of fines with coarse iron ore at a controlled particle size distribution supplemented by small dosages of low-cost additives may be employed for preparation and transportation of high-concentration iron ore slurry with improved pipe economics.