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ENERGY
ReTseeacrhcnho l oagnyd
Branch
Recent Studies of Coal Mining,
Cleaning and Upgrading
Projects supported in part by the Alberta/Canada
Energy Resources Research Fund and the Action
Committee on Western Canadian Low-Sulphur
Coal to Ontario
ALBERTA
OFFICE OF
COAL
RESEARCH &
TECHNOLOGY
Digitized by the Internet Archive
in 2016
https://archive.org/details/recentstudiesofcOOalbe
Recent Studies of Coal Mining,
Cleaning and Upgrading
Projects supported in part by the Alberta/Canada
Energy Resources Research Fund and the Action
Committee on Western Canadian Low-Sulphur
Coal to Ontario
Ahsna
1992 ENERGY
Edmonton Research and Technology Branch
ISBN 0-86499-865-1
Pub. No. T/257
Disclaimer
The contents of this publication are based on the
information and data obtained from, and the results and
conclusions of, research projects conducted by
independent researchers with financial assistance from
either the Alberta/Canada Energy Resources Research
Fund or the Action Committee on Western Canadian
Low-Sulphur Coal to Ontario.
The contents of this publication do not necessarily reflect
the views of the Government of Alberta, its officers,
employees, agents, or the Alberta/Canada Energy Resources
Research Fund Committee, or the Action Committee on
Western Canadian Low-Sulphur Coal to Ontario.
Neither the Government of Alberta nor its officers,
employees or agents makes any warranty, express or
implied, representation or otherwise, in respect of,
or assumes any liability for, the contents of this
publication.
1
Foreword
Beginning in 1976, numerous projects were The Alberta Office of Coal Research and
initiated in Alberta by industry and academic Technology is the agency through which
research institutions to help make better use funding contributions by the Government of
Alberta and A/CERRF are provided to coal
of Alberta's energy resources.
research and development projects in industry,
Most of these research, development and academic institutions and other research
demonstration efforts were funded by the establishments. As part of its mandate, the
Alberta/Canada Energy Resources Research Office monitors the progress of these research
Fund (A/CERRF), which was established as a projects in an overall program designed to
result of the 1974 agreement on oil prices improve the production, transportation and
between the federal government and the oil- marketability of Alberta coals.
producing provinces.
The A/CERRF program ended on March 31,
Responsibility for applying and administering 1991, and the support it p rovided has been
the fund rested with the A/CERRF Committee, replaced by funding from the Alberta
made up of senior Alberta and federal government.
government officials.
A s eries of technology transfer booklets,
A/CERRF program priorities focused primarily on begun in 1986 with A/CERRF support,
coal, energy conservation and renewable continues to make research results available to
energy, and conventional energy resources. In industry and others who can use the
1988/89, a hydrogen research component was information. This service will continue until all
added. A/CERRF projects have been described.
Administration for the A/CERRF program was For more information about other publications
provided by staff within the Research and in the series, please refer to page 13.
Technology Branch of Alberta Energy.
For more information about the program to
In recognition of the importance of coal to encourage greater use of western Canadian
coal in Ontario, contact:
Alberta's economy, the Alberta Office of Coal
Research and Technology was established in
1984 within Alberta Energy and Natural Chairman
Resources (now Alberta Energy). Its primary Intergovernmental Secretariat to the
purpose is to encourage the development and Action Committee on Western Canadian
application of new technologies related to Low-Sulphur Coal to Ontario
Alberta coals. Alberta Energy
11th Floor, North Petroleum Plaza
In 1987, the Action Committee on Western 9945 - 108 Street
Canadian Low-Sulphur Coal to Ontario was Edmonton, Alberta
established. It comprises the Deputy Prime T5K 2C9
Minister and the premiers of British Columbia,
Alberta, Saskatchewan and Ontario. The
Telephone: (403) 427-8042
purpose of the Committee is to foster greater
use of western Canadian coal in Ontario. This Telex: 037-3676
would provide social and economic benefits in
both Ontario and western Canada, and Fax: (403) 422-0975
substantially improve the air quality associated
with coal-burning in Ontario. The research
program of the Committee is administered by
an Intergovernmental Secretariat whose
members represent all the participating
governments.
2
Recent Studies of Coal Mining,
Cleaning and Upgrading
Introduction
In a world coal market characterized by combustion performance characteristics, and
considerable competition, depressed prices and to recover more fines in the form of
emerging coal-use technologies, it is recognized economically valuable products.
that Alberta coal companies must find ways to
remain competitive. To do this, they must mine Some of these research projects were funded
and prepare coal more efficiently for a market in part by the Alberta/Canada Energy
that is becoming increasingly sophisticated. It is Resources Research Fund (A/CERRF), while
clear that coal consumers have become more
others received support from the provincial
demanding about product consistency in terms and federal government participants in the
of combustion characteristics, ash production Action Committee on Western Canadian Low-
and the formation of air pollutants. To satisfy Sulphur Coal to Ontario. The Government of
these demands, techniques for removing non- Alberta is a member of this committee, and
combustible mineral matter and moisture in
Alberta's financial contributions are made from
coals are constantly being improved. This not the Alberta Heritage Savings Trust Fund.
only allows producers to supply higher quality
coals, but also minimizes the costs of shipping The results of this research are reported here.
non-combustible substances having no Earlier studies were described in 1988 and
economic value.
1 989 in the technology transfer publications.
Development of an Agglomeration Process to
Although washing continues to be the most Beneficiate and Transport Alberta Coals; Coal
common coal preparation method, in Alberta it Preparation Research in Alberta; and Studies
generates substantial quantities of tailings from of Fine Coal Cleaning and Upgrading Processes
the clays and fines associated with Alberta for Alberta Coals.
coals. These tailings represent lost product and
require large storage lagoons as an
environmental protection measure. Therefore, Automated Machine Control
alternatives to current washing techniques are
needed. for Optimized Mining
(AMCOM)
Also, as modern fuel standards have become
more stringent in response to the availability of
new or improved combustion technologies, coal In 1987/88, a detailed review was made by
researchers world-wide have begun to develop the Coal Mining Research Company of non-
methods to upgrade coal into products that cable vehicle guidance systems that might be
have been energy-enhanced or which produce used in Alberta's coal industry, and might also
fewer nitrogen and sulphur oxides when provide an opportunity to manufacture new
burned.
eprcoodnuocmtys., thereby diversifying Alberta's
A broad range of research investigations
covering all these issues is being pursued in In this project, some of the reviewed
Alberta, particularly those studies aimed at technologies included systems based on
upgrading bituminous and subbituminous coals inertial guidance, dead reckoning, radar, laser
to enhance their energy content and beacons, ultrasonics, machine vision and radio
frequencies.
3
The most promising systems were investigated
in terms of range, accuracy, flexibility,
reliability and costs. Plans were developed for
constructing a single prototype and testing it
under local mining conditions. This project was
described in 1989 in the technology transfer
booklet. Advanced Coal Mining Techniques for
Alberta.
Experience gained from this project led to the
development of an improved dragline monitor
and an automated machine control system for
selectively mining coal adjacent to partings
and waste material.
AMCOM, installed on a b ulldozer, was used in
The latter device, known as Automated mine-site tests.
Machine Control for Optimized Mining (Photo courtesy of Coal Mining Research Company)
(AMCOM), is intended to help reduce the
amount of coal lost, and the amount of foreign
material introduced, when mining occurs at Precision Of Blade Elevation Control
coal/waste interfaces. In some mining AMCOM MINE-SITE TRIALS
operations, for example, more than 10 per
cent of the total coal reserves are lost in this
manner. In other cases, excessive amounts of
foreign material are mixed with coal. This
causes problems in power plant boilers and
preparation plants.
The AMCOM design comprises four modules,
each of which uses proven, off-the-shelf
components. The four modules are:
• a coal quality sensing module;
Horizontal Distance (metres)
• a computing/lithology-mapping module; Standard Deviation ot Control Error = 9.6 mm
(Source: Automated Machine Control For Optimized Mining,
• a navigation/vehicle-position tracking Dauqela, G.C., B.G. Hollingshead, G L . Hoffman and R.A. Wilson.
module; and Coal Mining Research Company, 1989)
• a machine control module.
Dragline Operations Monitor
During 1988/89, all four modules were
developed and installed on a Bobcat loader for
initial field testing. The test showed that the
The second project evolving from the non-
AMCOM could control the elevation of the cable vehicle guidance project, and carried out
Bobcat bucket within 10 mm of the required by the Coal Mining Research Company, was
position. Subsequently, the system was the development of a dragline monitor to help
installed on a bulldozer and tested at a coal improve the efficiency of dragline operation
mine. Here, the system provided a reliable and reduce mining costs.
electronic map of the elevation of the
coal/waste contact in the working area, and In a typical overburden-removal operation at
the control strategy employed by AMCOM an open-pit coal mine, a dragline operator is
provided the required control precision. Also, required to co-ordinate several controls and
the AMCOM operated satisfactorily during make frequent changes to operating
adverse weather conditions. techniques. Without some form of measuring
4
device, it is difficult for the operator to
determine accurately the advantages of one
WESTCOAL Separator
technique over another. A d ragline monitor,
however, can record information quantifying
the performance of the dragline in various When coal and associated refuse are mined
operational modes and the performance of
and processed, they break into smaller
individual operators as they use different particles. Thus, it is impossible to avoid
techniques. producing some fines and slimes, which are
defined as being 1 mm x 0 .1 mm and <0.1
In this project, an existing dragline monitor mm in size, respectively. For western
was obtained from Interactive Sciences Inc. in
Canadian coals, the proportion of fines and
the U.S.A., and modified to record various
slimes is typically twice that of coals from
machine functions. The modifications were
other coal-producing areas. Also, the refuse
made primarily to assure the generation of associated with western Canadian coals tends
confidential information, but other alterations to be soft. Therefore, considerable effort and
were made to accommodate the requirements cost must be expended to clean the fines and
of western Canadian coal mine operators. slimes found with western Canadian coals.
Actual data from a U.S. coal mine were used
The principal method for cleaning coal is
to demonstrate the monitor's capabilities. gravimetric separation, while fines and slimes
While the productivity of large draglines varies are commonly cleaned by froth flotation
from one operator to another, use of the techniques. Because the relative density of
dragline monitor showed that these
coal is related to its non-carbonaceous, or ash,
differences can be recorded and identified.
content, cleaning with gravimetric separation
It was concluded that the device could be allows a desired ash content to be achieved
used successfully to train operators because it when coal having a certain range of relative
allows them to emulate the techniques of densities is recoverd from the process. For
individuals who are proficient at specific tasks. western Canadian coals, an accurate
Also, use of the dragline monitor might
separation in the relative density range of 1.5 -
enhance the prospects of partially automating 1 .7 is often required.
the operation of a dragline.
Devices known as spiral separators are
Dragline Operations Monitor Sample Report generating interest in western Canada because
OPERATOR PERFORMANCE ASSESSMENT they can recover fine coal more accurately
than other devices and are reputed to have
stable operating characteristics. Thus far,
however, the lowest "cut-point" range
available is approximately 1.9 - 2 .2.
Therefore, to optimize production and satisfy
out-of-province and export markets, the
objective of a project undertaken by the Coal
Mining Research Company was to design and
develop a device, known as the WESTCOAL
Separator, specifically for western coals. In
particular, the device was intended to have an
appropriate density "cut point" and a higher
unit capacity.
(Source: Dragline Operations Monitor, Daugela, G.C. and B.G.
Hollingshead, Coal Mining Research Company, 1989)
5
Using an existing spiral separator that was in It was found that the dried coals, whether
operation at the Obed Mountain coal mine, treated with ARCOFLUX 130 or not, were
several modifications were made to the device significantly more reactive than the
and its operation. Some resulted in poorer comparable moist feed. Also, it was noted
performance, but eventually a combination of that the coals treated with ARCOFLUX 1 3 0
modifications was found that achieved the did not exhibit significantly improved stability
desired improvement in separation or moisture sorption properties relative to the
performance and resulted in a lower ash untreated dried coals.
content in the recovered coal.
Testing also showed the following:
It was recommended that a patent be sought
for the WESTCOAL Separator, and prospective • when applied at rates of two or three per
manufacturers be approached regarding their cent, ARCOFLUX did not significantly reduce
interest in fabricating the device. A p reliminary the oxygen absorption potential or the
market survey showed that sufficient potential production of carbon monoxide and carbon
for use of such a device exists in North dioxide by dried coal;
America to proceed with developing and
producing this product. Because the • at the same application rates, ARCOFLUX
mechanical and operating details are 130 did not reduce the equilibrium moisture
confidential, additional information about the ccooanltse;n t or moisture sorption potential of
WESTCOAL Separator is available from the
Chairman of the Office of Coal Research and
Technology. • ARCOFLUX 130 has excellent dust
suppression properties;
• ARCOFLUX 130 can significantly reduce the
Testing of ARCOFLUX 130 flow characteristics of coal; and
• the presence of surface clays appeared to
In a patented process of the ARCO Petroleum reduce the coating effectiveness of
Products Company, coal is dried to less than ARCOFLUX 130.
its equilibrium moisture, and then cooled. This
is followed by treatment with a roofing asphalt The project was financed by Obed Mountain
product called ARCOFLUX 1 30. The treated Coal Company Limited, the federal Department
coal is reported to be dust-free, free flowing of Western Economic Diversification,
and more stable than untreated coal. To Saskatchewan Energy and Mines, Ontario
determine whether similar results would occur Ministry of Energy and the Government of
with Alberta coals, a study was carried out by Alberta. Alberta's contribution was
the Coal Mining Research Company involving administered by the Office of Coal Research
ARCOFLUX 1 30 as a potential deactivant to and Technology.
prevent thermally dried low-rank coals from
combusting spontaneously.
Coals from the Obed Mountain, Highvale and Particle Distribution in Slurry
Costello mines were dried in a Roto-Louvre
Flow Through Tees and
Dryer to less than their equilibrium moisture
Manifolds
content, the values being 8, 8 and 17 per
cent, respectively. After cooling, the dried
coals were treated by spraying with
ARCOFLUX 130. Two-phase (solid/liquid) flow through a
manifold is used commonly in industry to
The stability of the treated coals with respect distribute solids to various processing units.
to spontaneous combustion and moisture This occurs in coal preparation plants as well.
sorption potential was determined and Because differences in inertia occur between
compared with the parent coals in a moist or the solid and liquid phases, the solids
dry, untreated state. concentration is not always the same in
6
various branches of a manifold. This led
University of Alberta researchers to conclude
HYDROSIZER for Fine Coal
that a study was needed to determine the
relationship between solids concentration in Recovery from Tailings
the branches and the main pipe, as well as
determining the upstream operating conditions
that can affect this relationship. The objective Coal-cleaning experience elsewhere has shown
was to achieve equal distribution of solids in that the patented HYDROSIZER device
each branch.
effectively separates low-density, undesirable
material from fine coal (0.55 mm x 0 .1 mm)
In a project carried out at the University of having specific gravity values of less than 1.5.
Alberta, a closed-loop piping arrangement
having a manifold with four branches and
In this project, the device was tested for the
valves was used to control slurry flow through first time on western Canadian coals. A p ilot
the branches. Isokinetic and conductivity unit at the Obed Mountain coal mine was fed
probes were installed to measure solids with a 1 .2 mm x 0 m m raw coal slurry
concentration upstream and downstream of
partially deslimed at 0.15 mm. Two full
the branch tees. Initial experiments involving
performance tests were undertaken over a
sand/water slurries were conducted, using
range of cut points.
three configurations of branches: upwards,
sideways and downwards. Also, three grades The performance was separately evaluated for
of sand were used: fine, medium and coarse. the following 2:1 size fractions: 1.2 mm x
0.6 mm, 0.6 mm x 0 .3 mm, and 0.3 mm x
It was learned that for sand-water slurries, 0.15 mm. Mass and ash balances, and float-
only the sideways branch orientation gave a sink analyses, provided data for determining
uniform solids distribution for the medium and partition curves for each fraction.
coarse ranges of particle sizes, whereas a
uniform solids distribution was achieved for all Low cut points were achieved for material
three piping orientations when fine sand was coarser than 0.6 mm, although the separations
used. were not as sharp as those reported in the
literature. Some suggestions were made to
The laboratory data were used to develop a improve this performance. Products coarser
model of solids distribution in the branches of than 0.3 mm met clean coal specifications for
the manifold. This empirical model, which was ash content. This result cannot be achieved by
used to predict the concentration of solids in other devices using single-stage cleaning of
each branch, was found to be accurate to this particular clay-contaminated thermal coal.
within 1 5 p er cent of laboratory observations.
This is considered to be adequate for design It was concluded that the HYDROSIZER can
purposes. be a useful device in existing western
Canadian coal preparation plants where a low
Experiments with polyvinyl chloride particles, or adjustable separation gravity is required.
having a specific density of 1.2, showed the
solids distribution for all three orientations was The project was financed by Obed Mountain
equally satisfactory. This is significant because Coal Company Limited and the Government of
the density of polyvinyl chloride is a better Alberta, through the Office of Coal Research
approximation to that of coal than is sand, and Technology.
which has a specific gravity of 2.6.
