Excelsior's NSH-5 hydraulic conductivity at five ft/d
2013-02-05 07:08 ET - News Release
Mr. Stephen Twyerould reports
EXCELSIOR MINING CORP.: HYDROLOGY TESTS CONFIRM SUITABLE CONDITIONS FOR IN-SITU RECOVERY AT GUNNISON
Excelsior Mining Corp. has released results from recent hydrological tests conducted at the Gunnison copper project, located in southeastern Arizona.
Aquifer testing at well NSH-5 indicated a hydraulic conductivity (K) of approximately 5 feet per day (ft/day) while aquifer testing at well NSH-4B had a K value of approximately 0.5 ft/day. These results confirm Excelsior's hydro-geological model and are higher than the average hydrologic conductivity of 0.4 ft/day (160 millidarcys) used in the Preliminary Economic Assessment (see news release dated December 1, 2011).
"We are very pleased with these results as they demonstrate not only our ability to predict hydrological conditions using our 3D structural model, but also demonstrate our ability to reproduce earlier results demonstrating the viability of in-situ recovery methods for our Gunnison Copper Project," says Stephen Twyerould, President and CEO of Excelsior.
The locations of these two wells were selected in order to validate the predicted aquifer conditions within highly and moderately fractured zones of the Gunnison Project's North Star deposit. Hydraulic conductivity is a measure of the efficiency with which water moves through rock; it is measured in feet per day and/or millidarcys.
Further results are expected this quarter, including new metallurgical data and new geological and resource models. All of these data will be used to complete a Pre-Feasibility study expected later this year.
Excelsior's new 3D structural geological model allows for the prediction of structural domains throughout the deposit, which in turn allow for the prediction of permeability conditions. From this structural model two sites were identified to validate the model and generate additional hydrological data for the up-coming Pre-Feasibility study. The locations were chosen to test medium and high flow zones representing the bulk of the copper oxide mineralization within the North Star deposit.
Five day constant rate pump tests were completed on wells NSH-5 and NSH-4B. These wells were surrounded by 13 observation wells at different radial locations and distances from the pumping wells. Both drawdown and recovery phases of the test were monitored in the individual test wells and observation wells. In addition, extensive geophysical logging, geological logging, assaying, and water quality sampling were completed for the test wells and various observation wells.
Well NSH-5 aquifer testing data indicated a hydraulic conductivity value of about 5 ft/day, measured over an interval from 724 to 1,024 feet below surface. Well NSH-4B aquifer testing data indicated a hydraulic conductivity value of about 0.5 ft/day over an interval from 685 to 1,031 feet below surface.
These results are consistent with previous hydrological testing performed at the North Star Deposit (see news release dated September 6, 2011), and are consistent with K values from similar ISR projects.
The Gunnison Copper Project is located in a remote section of Cochise County in southeastern Arizona. The focus of the project is the North Star deposit, which currently has a total Indicated mineral resource of 3.21 billion pounds of oxide copper (511 M tons at 0.31%) and an Inferred mineral resource of 0.88 billion pounds of oxide copper (159 M tons at 0.28%). This oxide mineral resource has the potential to be mined using in-situ recovery methods. Please note, mineral resources which are not mineral reserves do not have demonstrated economic viability.
Tim Oliver, P.E., Mining Services Manager at Haley & Aldrich, Inc., Tucson, AZ, reviewed the well construction, test protocol, results and calculations disclosed in this news release and finds them sound and reasonable. Mr. Oliver is a Qualified Person (QP) as defined by NI 43-101.
Excelsior's exploration work on the Gunnison Property is supervised by Dr. Stephen Twyerould, Fellow of AUSIMM, President and CEO of Excelsior, and a Qualified Person as defined by NI 43-101. Dr. Twyerould has reviewed and approved the technical information disclosed in the "Project Summary" and "About Excelsior" sections of this news release.
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