Rheology modifiers for water-based slurry pipeline transportation: overview, efficiency, and intensification

Owing to their cost-efficiency and eco-friendliness, water-based slurry pipelines are the state-of-the-art technology for the transportation of several types of solids such as coal, fly ash, petcoke, iron ore, phosphate rock and other minerals. This review comprehensively examines the effect of numerous commercial dispersants and novel chemical additives that are used as rheology modifiers to enhance the slurryability and fluidity of solid-water slurries at high solids loading. Several key performance parameters such as the rheological characteristics (shear stress, apparent viscosity, yields stress, and flow behavior), the potential stability, surface tension and contact angle that highlight the efficiency of the rheology modifiers were thoroughly reviewed and the adsorption mechanisms of the chemical additives on the surface of the solid particles were discussed. Generally, the efficiency of the chemical additives was found to strongly depend on the features of the additives (dosage, molecular weight, functional groups, …), the surface properties of the solid material, and the characteristics of the slurry. The reviewed studies indicate that conventional dispersants typically reduce apparent viscosity by 20-40%, while biosurfactants achieve reductions of 30-50%. More advanced graft copolymers and nanoparticle-assisted dispersants can reduce apparent viscosity by 50-80%, while enabling solids loadings above 70wt% at low additive dosages (<0.5wt%). Furthermore, synergistic additive mixtures have been shown to reduce pipeline pressure drop by up to 50%, demonstrating the strong potential of multi-component dispersant systems for industrial slurry transportation. Furthermore, the shortcomings of some methodologies used were critically analyzed and recommendations for future research were provided.