Coal and Coal Products: Analytical Characterization Techniques

322 Pages·1982·5.63 MB·English

by  E. L. Fuller

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In Coal and Coal Products: Analytical Characterization Techniques; Fuller, E.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1982.
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In Coal and Coal Products: Analytical Characterization Techniques; Fuller, E.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1982.
Coal and Coal Products:
Analytical Characterization
Techniques
E. L. Fuller, Jr., EDITOR
Union Carbide Nuclear Division
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8 Divisions of Analytical,
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21/ Fuel, and Colloid
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ACS SYMPOSIUM SERIES 205
AMERICAN CHEMICAL SOCIETY
WASHINGTON, D. C. 1982
In Coal and Coal Products: Analytical Characterization Techniques; Fuller, E.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1982.
Library of Congress Cataloging in Publication Data
Coal and coal products.
(ACS symposium series, ISSN 0097-6156; 205)
Includes bibliographies and index.
01 1. Coal—Analysis—Congresses.
w0 I. Fuller, E. L. II. American Chemical Society.
5.f Division of Analytical Chemistry. III. American
0 Chemical Society. Division of Fuel Chemistry. IV.
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0 American Chemical Society. Division of Colloid and
82- Surface Chemistry. V. Series.
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k-1 TP325.C5145 1948 622.6'22 82-18442
b ISBN 0-8412-0748-8 ACSMC8 205 1-326
21/ 1982
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n Copyright © 1982
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blic American Chemical Society
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PRINTED IN THE UNITED STATES OF AMERICA
In Coal and Coal Products: Analytical Characterization Techniques; Fuller, E.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1982.
ACS Symposium Series
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1 Donald D. Dollberg Leon Petrakis
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Herbert D. Kaesz Gunter Zweig
In Coal and Coal Products: Analytical Characterization Techniques; Fuller, E.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1982.
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0 FOREWORD
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bk- The ACS SYMPOSIUM SERIES was founded in 1974 to provide
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98 mitted by the authors in camera-ready form. Papers are re
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In Coal and Coal Products: Analytical Characterization Techniques; Fuller, E.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1982.
PREFACE
THE INDUSTRIAL REVOLUTION was based upon efficient use of mechanical
energy for production and processing of materials. The initial source of
this energy came from the thermal energy stored in coal, but rapid advance
ments were made, and petroleum soon replaced coal as the prime source
of energy to support an increased standard of living for mankind. The
world's population has increased to such a staggering extent that the
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5. ties just to provide essential life-supporting food, clothing, and shelter.
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98 each of us must work to provide services and products that are needed
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k- by others. This increase in efficiency allows us to inhabit the earth at a
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21/ population density and state of well being far in excess of the hunter/
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0.1 farmer status of the past.
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oi: However, this mode of operation strains our natural resource supplies
2 | d to varying degrees. The recent "energy crisis" serves a good purpose: it
98 points out that comprehensive planning and research are required to ensure
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2, that mankind can flourish and that the raw materials are carefully and
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er efficiently utilized. The simple political control of one supply of energy
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m (crude oil in this case) from one rather small geographic region has suddenly
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atio provide charcoal for the steel industry.
blic We now have adequate information, processing capabilities, technical
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implemented without the tragic impact of "crisis" situations. Our sources
of energy can be brought into play without significant impact on the
environment if proper comprehensive analysis is employed. Coal still reigns
among sources of energy in terms of the amount and availability. The
generically related materials (oil shales, tar sands, lignite, peat, heavy oils,
etc.) further extend the importance of fossil fuels for energy bases.
This volume represents a small step toward the research and inter
disciplinary communications required to return efficiently to our large
reserves of coal for a primary source of energy. Each presentation chosen
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In Coal and Coal Products: Analytical Characterization Techniques; Fuller, E.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1982.
for this volume represents a significant contribution to either a specific area
of technical importance in coal processing and utilization, or a specific
application of a given method of analysis as applicable to various coals and/
or derived products.
New and/or alternate approaches to studies of the structure and
chemistry of coals and related materials will yield increased productivity
and improved environments. In our small way this treatise is our current
international effort to advance the technology we all need.
E. L. FULLER, JR.
Union Carbide Nuclear Division
Oak Ridge, TN 37830
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In Coal and Coal Products: Analytical Characterization Techniques; Fuller, E.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1982.
1
Theoretical and Experimental Approaches
to the Carbonization of Coal and Coal Blends
MAGGI FORREST and HARRY MARSH
University of Newcastle upon Tyne, Northern Carbon Research Labs,
School of Chemistry, Newcastle upon Tyne, NE1 75U, England
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5.c Mechanisms of carbonization of fluid systems from pitches and
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2 coals of different origin and rank to form anisotropic cokes are
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2- discussed. The concept of nematic liquid crystals and mesophase is
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19 introduced. The origins of optical texture in cokes and the
k- chemical and physical factors which control the size and shape of
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10 in metallurgical cokes is analysed in terms of coke strength and
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1 chemical reactivity. Laboratory experimental approaches include
oi: control over carbonization procedures, the examination of polished
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98 scanning electron microscopy to monitor changes induced by thermal
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2, treatment and gasification of cokes, as well as point-counting of
er 1 optical texture and the use of microstrength testing procedures.
b Modern technological approaches to the successful use of coals of
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e several ranks to make metallurgical coke include blending of coals
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No sometimes with pitch additions. The resultant enhancement of coke
e: strength is explained in terms of the development of suitable
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on Hydrogen transfer reactions are important here. The use of breeze
ati additions in coal blends is commented upon.
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Metallurgical coke is used in the blast furnace as an energy
source, a chemical reducing agent and to provide permeability and
support for the furnace load. To fulfil these functions and
maintain blast furnace performance the coke must maintain its size
within an optimum range. It must therefore be able to maintain
its mechanical strength and to withstand degradation due to gasifi
cation in carbon dioxide, abrasion, compressive forces and thermal
shock in the furnace. Prime coking coals of volatile content
19-33% are becoming scarce in Western Europe and Japan and economic
necessity dictates the need for the development of blending
0097-6156/82/0205-0001$07.50/0
© 1982 American Chemical Society
In Coal and Coal Products: Analytical Characterization Techniques; Fuller, E.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1982.
2 COAL AND COAL PRODUCTS
procedures which make use of coals of volatile content above and
below this critical range. The characteristics of cokes from such
blends must fall within stringent specifications to maintain blast
furnace performance (1). It is therefore necessary to combine the
results of fundamental research with experience gained from the
past empirical approach to coal blending (£). The purpose of this
paper is to discuss recent theoretical considerations and experi
mental studies of coal and coal/pitch blending procedures,
gasification and thermal treatment of metallurgical cokes and the
effects of pitch coke breeze additives upon coke strength.
The Carbonization Process
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0 The Formation of Anisotropic Carbon. As coal is heated it
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20 evolution of gas and condensible vapours and leaves behind a solid
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10. Over the temperature range 623 K to 773 K, caking coals begin
oi: to soften, coalesce,swell and then re-solidify into a porous
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98 temperature, is green coke.
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er 1 Initial softening of the coal is due to increased thermal
b agitation. At the same time, but independently of the physical
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e process, pyrolysis begins to modify the viscosity of the coal by
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No breakage of the chemical cross-linkages responsible for making
e: coal a polymeric material. Swelling of the mass is due to the
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on and which encounters resistance to its flow through macropores and
ati fissures in the coal C5).
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of molecular constituents so converting the plastic state into a
visco-elastic state and finally into a brittle porous solid.
Similarly, coal tar and petroleum pitches, on carbonization,
form a fluid melt. The viscosity of this melt initially decreases
with increasing temperature and then increases once again as
molecular reactivity leads to chemical polymerization. Eventually
these materials form the anisotropic graphitizable cokes.
It is during the plastic (fluid) stages of carbonization that
the most important features of coke structure are formed,
particularly porosity (6) and pore wall structure. During the
plastic stage, the optically isotropic parent material undergoes
a phase transition to an optically anisotropic melt which finally
In Coal and Coal Products: Analytical Characterization Techniques; Fuller, E.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1982.