Rheological characteristics of Chinese Shenmu coal ash slag at high-temperature

The rheological behavior of Chinese Shenfu coal ash slag was investigated experimentally by using a high-temperature rheometer at temperatures between 1200°C and 1360°C. The effects of shear rate and temperature on the rheological behavior of the coal ash slag were studied. A metallurgical microscope was used to study the crystalline phase of the quenched sample at different temperatures. The computer software package FactSage was used to predict the proportions of solids and the compositions of the remaining liquid phase. The liquidus Urbain model was used to describe the viscosities of the homogeneous liquid in coal ash slag in a wide range of temperature. The modified Einstein-Roscoe equation was used to describe the effect of presence of solid suspension on the viscosity of partly crystallized coal ash slag. The results showed that, at its liquidus temperature calculated by FactSage, the coal ash slag behaved as a Newtonian fluid, below its liquidus temperature, however, the rheological behavior of the coal ash slag became non-Newtonian owing to its increased solid-phase content. Meanwhile, at a high crystal content, coal ash slag exhibited shear thinning behavior. The models provided a good description of the experimental data of fully liquid and liquid+solid mixtures. The modified Einstein-Roscoe equation satisfactorily estimated viscosities of the coal ash slag at different crystal contents.