Promotion of Coal Slime Water Sedimentation and Filtration via Hydrophobic Coagulation

ABSTRACT

Highly turbid coal slime water is characterized by high concentrations of fine particles with negative electric charges and a high clay content. These characteristics hinder the sedimentation and dewatering of highly turbid coal slime water. Therefore, we investigated the initial settling velocity, light transmittance, and filter cake moisture content, as well as the effects of quaternary ammonium surfactants on sedimentation and filtration of coal slime water. Amendment with quaternary ammonium surfactants promoted the sedimentation and filtration of coal slime water by enhancing the hydrophobicity of particles and decreasing the electric charge on particle surfaces. In addition, factors such as kinetic energy input (i.e., mixing), reagent type and dosage, solution pH, the size and mineral composition of coal slime water particles affected sedimentation and filtration. For example, under prolonged treatment with quaternary ammonium containing long alkyl chains, the contact angle of slime particles increased, leading to improved sedimentation and dewatering. Further, high quartz and clay mineral contents exerted unfavorable effects on sedimentation and filtration. Also, the optimal solution pH conducive to sedimentation and filtration ranged from 8 to 10. The results of this study should help improve coal slime sedimentation and filtration processes because the study addresses current technological limitations.

KEYWORDS:

• Aggregate
• coal slime water
• dewatering
• hydrophobic coagulation
• interface

Acknowledgments

This work was sponsored by the Natural Science Foundation of China [51874011].

Additional information

Funding

This work was  sponsored by the Natural Science Foundation of China [51874011].