The potential of QEMSCAN in predicting coal washability of Mpumalanga coals

Traditional float and sink analyses are undertaken to determine the washability of coal. Float and sink analyses are costly, require toxic heavy organic liquids and the procedure to wash and dry the float and discard fractions is lengthy. QEMSCAN has the ability to characterise particle density based on the mineralogical composition of the particle. The objective of this research is to determine if QEMSCAN is a viable alternative to float and sink analysis. Float and sink analysis typically requires coarse size fractions while QEMSCAN analysis requires samples to be crushed down to 1mm. Any crushing will liberate minerals, which will alter the particle density distribution. Crushing a large particle generates 'puzzle pieces' of the original particle. The smaller 'puzzle pieces' have densities frequently different to the original particle. A mineralogical based particle density prediction model confirms that the float and sink analysis data used in this study is valid. The measured ash contents for the different float and discard fractions were within the expected limits. It is observed that there are a set of controls over the liberation of particles when crushed. Particles in the low float fractions (<1.6g/cm3) predominantly comprise vitrinite rich coal with fine lamellae of kaolinite. The higher float fractions (>1.6-2.0g/cm3) comprise bright and dull coal incorporated into an 'inertodetrinite' texture. Cleats and kaolinite laminae serve as preferential cleavage planes in the lower density fractions, while bright and dull coal serve as preferential breakage planes in the higher float fractions. As a result, these phases are liberated and there is evidence to support that liberation of minerals have controls that can be identified and corrected for. Thus, washability can be determined using QEMSCAN since the significant effect of liberation can be calculated and corrected, for a specific coal type.

Grantor dc:publisher

University of Pretoria

Year dc:date.issued

2015

Advisor dc:contributor.advisor

• Merkle, R.K.W. (Roland Karl Willi), 1954-

• UCTD
• QEMSCAN
• Coal washability
• Mpumalanga coals
• Coal beneficiation
• Dense medium separation (DMS)
• Coal preparation

Statement dc:rights

• © 2017 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria.

Language dc:language.iso

en

Dc Identifier Other

A2017

OAI identifier oai:identifier

oai:repository.up.ac.za:2263/60858