高濃度石炭-水混合物(CWM)のチキソトロピー
1986 年 14 巻 3 号 p. 123-127
詳細
1986 年 14 巻 3 号 p. 123-127
The shear stress-shear rate behavior of a thixotropic coal-water mixture(CWM) was studied in a coaxial rotating cylinder rheometer under a wide variety of rest and shear rate history. The transient stress data were used to construct equilibrium and constant-structure flow curves. These transient stress data, i. e. the stress relaxation data and the stress recovery data, were also used to evaluate the breakdown and buildup processes of the internal structure. A phenomenological thixotropy model, which had the structural stress as a thixotropic structural parameter, was proposed. Dependence of thixotropic parameters on pH values of CWM was experimentally determined. Strong dependence of the time constant for buildup of structural stress on pH values was observed, and this phenomenon corresponded to the rapid coagulation of coal particles at lower pH values. However, coagulation and dispersion of coal particles could not be explained by the simple hetero-coagulation theory with measured zeta-potential values.
