Abstract
In deep sea mining, it is necessary to transport marine mineral resources from the seafloor in the depth of over 1,000 m to sea surface. To enhance transportation efficiency, a method using the mixtures of bentonite suspension and sand particles as the carrier material (CM) was proposed. Meanwhile, the viscous characteristics of CMs (the relationships between the shear stress, τ, and the shear rate, ý) are one of the most important properties to evaluate the pumpability and lifting efficiency. In this study, a new tube-type viscometer, the falling head flow test (FHFT) was proposed for Bingham fluids containing solid particles. To measure the viscous characteristics of CMs, FHFTs were conducted using the bentonite suspension with and without sand particles. The measured results demonstrated the flow curves of CMs can be modelled by bi-linear lines with two gradients crossing at ý≒1.0 /s. Moreover, the relationships between the viscous parameters (the plastic viscosity ηp and the yield stress τy) and the mixing proportions of CMs were modelled.
