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Our
Expertise . . . |
Trona Projects
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FMC Wyoming Corporation,
Wyoming, USA
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FMC Corporation, Wyoming, USA
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General Chemical, Wyoming, USA
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OCI Wyoming, L.P., Wyoming, USA
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Solvay Minerals, Inc., Wyoming,
USA
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Tg soda ash inc.,
Wyoming, USA
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Wold Trona Company, Inc.,
Wyoming, USA
FMC Wyoming Corporation, Longwall Gateroad Analysis,
Green River, Wyoming, USA
AAI performed a comparative stability evaluation for the East
Longwall Panel 8 Gateroads. Four different gateroads were analyzed,
including three- and four-entry layouts. Analyses were performed using SALT4
and EXPAREA, both of which can model time-dependent salt behavior. SALT4 was
used for two-dimensional analyses of gateroad profile stresses, while
EXPAREA was used to analyze vertical pillar stresses. An instrumentation
program was implemented to confirm the modeling effort.
 FMC Corporation,
Alkali Chemicals Division, Absolute Stress Determinations, Green River,
Wyoming, USA
Agapito Associates, Inc. was retained by
FMC Corporation to determine absolute vertical stress levels at two
locations previously instrumented with vibrating wire stress meters.
The USBM borehole deformation gage and overcoring method was to be used for
the stress determination. The measurements served two purposes:
(1) to quantify load transfer and (2) to establish a stress baseline in
the pillars. AAI provided all drilling equipment, two technicians,
overcoring equipment, and specialized tools and supplies required for
operation, calibration, and maintenance of the gages and equipment.
Two horizontal holes 45 ft deep with six
overcore runs each were completed. The holes were drilled
perpendicular from two 9-ft-high by 15-ft-wide entries mined with a bore
miner. The project was completed in 11 days with no accidents or
incidents. Mobilization into and demobilization out of the mine were
expedited by the ability to hoist AAI's loaded trailer, saving several
manual transfers of the equipment and supplies required to complete the
project.
A report of the details of the project
and stress determination results was completed and submitted to FMC.
General Chemical, Alchem Mine, Green
River, Wyoming, USA
The Alchem Mine utilizes continuous miners in a room-and-pillar
layout to produce trona from a single seam. AAI evaluated stability of
two-seam mining as part of a feasibility study. This work included
laboratory testing for rock properties to be used in the mining evaluation,
numerical modeling of stress interactions from two-seam mining, and modeling
of open stability. AAI was also involved in the review and evaluation of a
five-year mining plan.
General Chemical, GCSAP Mine Bed
14 Feasibility Study, Green River, Wyoming, USA
A detailed analysis of the feasibility of mining Bed 14 was
conducted, including a conceptual mine plan and cost estimate. Ore reserves
were estimated from drill hole data. General arrangement drawings were
prepared for concurrent, multi-seam mechanical mining of Beds 14 and 17.
Potential ground control issues and ventilation were analyzed. A capital cost estimate for
Bed 14 access and an operating cost estimate for mining were developed.
OCI Wyoming, L.P., Big Island Mine,
Green River, Wyoming, USA
AAI has conducted a variety of mine design projects for the Big
Island trona mine since 1976. In addition to numerous rock mechanics
investigations, the firm has evaluated two-seam room-and-pillar mining
systems, investigated the effect of underground tailings emplacement on
pillar stability, designed ground support for underground ore bins and
ramps, conducted ventilation surveys, and helped design the ventilation
system for mine expansion. The most significant projects involved the design
of a yielding pillar mining system to increase the extraction ratio. Design
and application of yielding pillars was initially tested in a small
instrumented area with a conventional panel. Pillar deformation and stress
changes were used to develop a viscoelastic creep formulation used in
simulating the long-term yielding of various panel layouts and extraction
ratios. Adoption of the yield pillar design led to an increase in both total
recovery and productivity.
As part of a multi-phase project to optimize the Big Island Mine, an
underground pressure and velocity survey was conducted. Aneroid barometers
were used to measure pressure drops throughout the mine and to construct
pressure gradients. Velocities were concurrently measured. A network model
was developed using the computer codes MTU and MFIRE, and calibrated to the
field measurements. The model has been used to assess ventilation
alternatives for expansion of mining options.
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Solvay Minerals, Inc., Longwall Rock
Mechanics Study, Green River, Wyoming, USA
AAI prepared a longwall feasibility study for Solvay that included
a gateroad design evaluation, barrier pillar review, face width evaluation,
support recommendation, subsidence evaluation, strata gas review, and
instrumentation plan.
Solvay Minerals, Inc., Rock Mechanics, Green River, Wyoming, USA
In 1995, AAI was commissioned by Solvay to investigate the collapse
of twelve panels in the southwest portion of the Solvay Mine. During this
study, AAI was involved with a review of existing geotechnical data,
laboratory testing for mechanical properties, overcore and undercore stress
measurements, core drilling, compilation of the data, and interpretation
with respect to current and future mine design. Numerical modeling was
conducted to assist in interpretation of measured stresses and to assist in
understanding load transfer mechanisms. A back-analysis was conducted of the
subsidence over the southwest portion of the mine using a proprietary
subsidence prediction code (BASIN) developed by AAI. Good agreement was
obtained between the measured and calculated subsidence.
Solvay Minerals, Inc., Stress Determinations and Testing, Green River,
Wyoming, USA
AAI completed field services work for Solvay. The project included
overcore stress determinations at three sites within the mine. The sites
were selected to provide information regarding in situ stress conditions in
advance of planned mining and in a main entry system influenced by the
extraction of adjacent mining panels.
In addition, samples of the trona, roof, and floor horizons were collected
and prepared for laboratory testing. Uniaxial and triaxial compression tests
were conducted to determine material properties, including unconfined
compressive strength, elastic modulus, Poisson's ratio, density, and
internal angle of friction.
The information developed was subsequently used for numerical modeling
analyses and stability evaluation.
Tg soda ash, inc., Longwall Rock Mechanics
Study, Granger, Wyoming, USA
Tg is investigating the feasibility of longwall mining in trona. A
longwall geotechnical evaluation was performed for Bed 20 that included
gateroad design evaluation, barrier pillar review, face width evaluation,
support recommendations, preliminary subsidence evaluation, strata gas
review, hydrologic effects, and instrumentation plan.
Tg soda ash, inc., Stability Evaluation of Shortwall Mining, Granger,
Wyoming, USA
A geotechnical program was developed for the design and stability
monitoring of shortwall mining applying microcomputer analyses of mining
layouts on a routine basis. Specific layouts analyzed consisted of a
shortwall mining system with advancing tailgate and a three-entry gate
system using 17-ft-wide pillars at a 1400-ft depth. A geotechnical
evaluation of the minability of Bed 20 was also made.
Wold Trona Company, Inc., Benetron Project,
Casper, Wyoming, USA
AAI developed the bid document package for the design and
construction of production and service shafts for this proposed trona mine
project in southwest Wyoming. The 4.5 MTY underground mine will be at an
approximate 1500-ft depth. The bid package includes sinking, headframes,
hoisting, shaft fittings, loading pockets, and underground mine development.
Services include pre-engineering, ventilation, equipment, mine development
logistics, etc., bid specifications, bidders list development, engineer's
estimate for capital and construction costs, interface with potential
bidders, and development of geologic/geotechnical database. Other roles
include the evaluation of resource minability and improvements to
productivity using available technology.
AAI conducted a geologic and rock mechanics characterization
program that included detailed structural logging, generation of a core
photographic record, and core testing to determine mechanical properties.
Detailed logs and characterization of the formations in the vicinity of
proposed access shafts were generated. These data were integrated with the
client's lithologic logs in a comprehensive Geotechnical Design Summary
Report (GDSR). The GDSR provided a basis for contractor preparation of shaft
sinking and bid estimates for development of shaft access to a proposed
underground trona mine.
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AGAPITO
ASSOCIATES, INC.