Rheological properties of dense medium suspension for coal preparation

ABSTRACT

Dense medium preparation is widely used in coal preparation, and the rheology of dense medium suspension is a key factor affecting the coal separation performance. The rheological properties of dense medium suspensions in coal preparation with density from 1.40 g/cm³ to 1.80 g/cm³ were investigated. A linear fitting correction method for measuring the viscosity of suspension with a rotary viscometer is proposed, which reduces the measurement error of suspension viscosity caused by particle sedimentation. The rheological equation of dense medium suspensions with 0-30% slime was determined. It has no obvious yield stress and can be described using a pseudoplastic fluid model. Proper addition of 0-7% kaolinite will increase the apparent viscosity of the suspensions, but it will not affect the characteristics of the pseudoplastic fluid in the suspension.

KEYWORDS:

• Dense medium suspension
• rheological properties
• coal preparation
• rheological parameters
• kaolinite

Nomenclature

${\rho }_{av}$	=	Average solid density, g/cm3
${\gamma }_1$	=	The weight of magnetite powder, %
${\gamma }_2$	=	The weight of magnetite powder, %
${\rho }_1$	=	The density of magnetite powder, g/cm3
${\rho }_2$	=	The density of magnetite slime, %
$\rho$	=	The density of suspension, g/cm3
$G$	=	Total mass of suspension, g
$G_1$	=	The weight of solid, g
$G_2$	=	The weight of water, g
$V$	=	Total volume of suspension, cm3
$V_1$	=	Total solid volume, cm3
$V_2$	=	Water volume, cm3
$\lambda$	=	Solid volume fraction of the suspension, dimensionless
$K$	=	Consistency coefficient, dimensionless
$n$	=	Power law index, dimensionless
$\tau$	=	Shear stress, Pa
${\tau }_0$	=	Yield stress, Pa
$\gamma$	=	Shear rate, r/min
$\eta$	=	Viscosity, Pa·s
R	=	Correlation coefficient, dimensionless
$S$	=	Mean square error, dimensionless

Additional information

Funding

The project was supported by the National Natural Science Foundation of China [Grant No. 51604281].

Notes on contributors

Xueshuai Zhu

Xueshuai Zhu is a professor and currently works at the School of Chemical and Environmental Engineering of China University of Mining and Technology (Beijing). His main research interests are coal beneficiation and clean utilization, and recycling of spent lithium-ion battery.

Junli Liu

Junli Liu, Xizu Yang and Chao Cao have respectively done Ph.D. in the third grade, postgraduate in the second grade and the third grade. They are currently majoring in mineral processing technology at China University of Mining and Technology (Beijing), whose research interests are mainly coal sorting and clean utilization.

Xizu Yang

Junli Liu, Xizu Yang and Chao Cao have respectively done Ph.D. in the third grade, postgraduate in the second grade and the third grade. They are currently majoring in mineral processing technology at China University of Mining and Technology (Beijing), whose research interests are mainly coal sorting and clean utilization.

Chao Cao

Ming Chen currently works at Ministry of Public Foundation at Hubei College of Chinese Medicine in China and engaged in basic theoretical research for several years.

Ming Chen

Ming Chen currently works at Ministry of Public Foundation at Hubei College of Chinese Medicine in China and engaged in basic theoretical research for several years.