Rheological Properties of High Concentration Coal Slime

Concentrated coal slime serves as a clean and promising fluid fuel and is commonly employed via pipeline transportation. Currently, there are still limitations in understanding the rheological properties of coal slime, including its yield stress, viscoelasticity, and the impact of factors, such as temperature, on these properties. Therefore, we conducted tests to examine the rheological properties and yield stress of coal slime at various temperatures for two different concentrations using a pipeline transportation system and rheometers. Furthermore, due to the challenges in measuring dynamic yield stress caused by the shear bands of highly viscous slime, a method using the residual pressure inside the pipeline after cessation of transportation is proposed. The viscoelasticity of coal slime at various temperatures was examined through oscillatory shear tests. Finally, the pressure wave velocity in the pipeline transportation system was used to determine the bulk modulus. The results indicated that the shear stress under high shear rates decreased with an increase in temperature, while the yield stress and shear stress under low shear conditions gradually increased with temperature. The coal slime exhibited certain viscoelasticity with shear elasticity increasing as the temperature rose. The pressure wave velocity in the pipeline remained constant and did not vary significantly with temperature.