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Proceedings Paper

An Investigation Of The Effect Of Particle Size On Oxidation Of Pyrites In Coal.
Author(s): Paul K. Chan; David C. Frost
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Paper Abstract

We have used X-ray photoelectron spectroscopy (XPS) to study the variation of surface pyrite density with coal particle size (53 4m - 250 4μm). We also detect and monitor pyrite oxidation to sulfate, an important process influencing the surface-dependency of coal-cleansing methods such as flotation. It is very likely that as coal is crushed as part of the processes employed to rid it of prospective pollutants one eventually reaches a pyrite size which may be called "characteristic". It is this parameter that we examine here. Good correlations are established between (i) the liberation of pyrite and particle size, (ii) surface pyrite/sulfate ratio, and (iii) oxidized and non-oxidized sulfur in a typical Canadian coal. For "non-oxidized", or "fresh" coal, the dispersion of pyrite on the coal surface is inversely proportional to coal particle radius, and the tangents of this curve intersect at a particular particle size (106±5 4μm). Although, for the oxidized coal, the appearance of the curves depend on oxidation time intervals at low temperature with humid air, there is an "optimum" particle size which exhibits maximum surface pyrite. Notably, this "optimum" size corresponds to the tangent's intersection for the non-oxidized coal, and hence the "characteristic" size of constituent pyrite. This should allow prediction of pyrite occurrence, a parameter of paramount interest in coal processing and cleaning technology. Coal surface characterization obtained by XPS after various conditioning steps and during flotation, allow both a functional analysis via the study of chemical shifts and a semi-quantitative analysis based on relative intensity measurements.

Paper Details

Date Published: 12 August 1986
PDF: 6 pages
Proc. SPIE 0690, X-Rays in Materials Analysis: Novel Applications and Recent Developments, (12 August 1986); doi: 10.1117/12.936605
Show Author Affiliations
Paul K. Chan, University of British Columbia (Canada)
David C. Frost, University of British Columbia (Canada)

Published in SPIE Proceedings Vol. 0690:
X-Rays in Materials Analysis: Novel Applications and Recent Developments
Thomas W. Rusch, Editor(s)

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