COAL AND MINERAL PARTICLES

University Coal Research Contractors Review Conference

Others  :  http://www.netl.doe.gov/publications/proceedings/97/97ucr/mazumder.pdf
PID  :  6024

来源: CEUR

【 摘 要 】

OBJECTIVE:The aim of our studies is development of a comprehensive physical and chemical model for electrostatic charging of coal carbons and mineral particles.Properties of the fundamental constituents of coal are analyzed in relation to bulk coal powders processed with a laboratory scale electrostatic separator.Characterization techniques include:quantitative sulfur analyses, single particle charge and mass measurements, petrographic analyses, ultraviolet photoelectron spectroscopy, and effects of chemical conditioning agents and oxidation on beneficiation.Electrostatic beneficiation may become commercially viable when the factors which influence charging properties of each maceral and mineral type is understood. WORK DONE AND CONCLUSIONS: A fluorescence petrographic microscope was equipped with a cube and polarizers for white light observation of coal particles and bulk coal specimens.This allows for improved ability to differentiate maceral and mineral types.In one study, charged copy machine toner powders are deposited onto charged or uncharged polished coal specimens.The powder deposits onto different types of macerals and minerals on the coal surface depending on experimental conditions.For example, when both the coal sample and powder are charged, powder deposits primarily on interfaces between macerals and minerals.Fringe field effects thus dominate.Conversely if the coal is not charged, then the charged toner powder adheres preferentially on inertinite macerals.Deposition of charged toner on inertinite is likely due to image charging of the inertinite by the toner since inertinite is the most electrically conductive maceral. Based on experiment and theory, the main points of our current chemical model for charging are as