Hydrologic mechanisms and optimization of in-situ copper leaching : case study-BHP Copper, San Manuel, Arizona

Persistent Link:
http://hdl.handle.net/10150/191229
Title:
Hydrologic mechanisms and optimization of in-situ copper leaching : case study-BHP Copper, San Manuel, Arizona
Author:
Williamson, Christian Thoreau.
Issue Date:
1998
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
In-situ copper leaching at BHP Copper's San Manuel open pit mine was established in 1986. Currently, over a thousand wells on the benches of the open pit mine are simultaneously injecting and pumping sulfuric acid solutions. A large-scale reconfiguration of the well field in 1996 led to a dramatic, yet temporary, increase in copper pounds, apparently due to changes in flowpaths. While the first reconfiguration was accomplished by means of hydrologic intuition, a question arose regarding the issue of whether subsequent reconfigurations supplemented with additional smaller scale characterization could ultimately lead to increased copper production. To study this question, two fifty-well sites were selected within the in-situ leach well field. Because in-situ leaching involves the movement of fluid within the subsurface, hydrology is a natural context in which to study the process. The desire to optimize well-to-well in-situ leaching for enhanced copper recovery through the fundamental understanding of important hydrologic mechanisms is the primary motivation for this dissertation. Hydrologic testing in San Manuel is inherently challenging due to the hydraulically dynamic environment. A hydraulic cross-hole testing procedure termed "Cyclic Pulse Testing" (CPT) was used to overcome this issue. Over 100 pressure responses obtained via CPT at the two test sites were examined by means of type curve analysis. The spatially distributed hydraulic parameters were analyzed within the framework of geostatistics. The kriged heterogeneous hydraulic conductivity fields were inputted into a numerical flow and transport model to study, along with other issues, the impact heterogeneity has upon the in-situ leaching process. A number of conclusions were reached based upon the investigation of the two test sites. Comparison between single-hole and cross-hole hydraulic tests revealed the probable presence of a low permeable skin surrounding the wells. By far, the most important hydrologic mechanism controlling the in-situ leaching process in San Manuel was the massively induced hydraulic background gradient, in places, on the order of 35°. Modeling revealed insignificant differences on the sweeping efficiency of the formation between heterogeneous and homogeneous simulations. However, due to the twodimensional nature of the collected data, additional three-dimensional information may lead to a different conclusion.
Type:
Dissertation-Reproduction (electronic); text
Keywords:
Hydrology.; Hydrology -- Arizona -- San Manuel.; Copper -- Metallurgy.; Copper mines and mining -- Arizona -- San Manuel.
Degree Name:
Ph. D.
Degree Level:
doctoral
Degree Program:
Hydrology and Water Resources; Graduate College
Degree Grantor:
University of Arizona
Committee Chair:
Neuman, Shlomo

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleHydrologic mechanisms and optimization of in-situ copper leaching : case study-BHP Copper, San Manuel, Arizonaen_US
dc.creatorWilliamson, Christian Thoreau.en_US
dc.contributor.authorWilliamson, Christian Thoreau.en_US
dc.date.issued1998en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractIn-situ copper leaching at BHP Copper's San Manuel open pit mine was established in 1986. Currently, over a thousand wells on the benches of the open pit mine are simultaneously injecting and pumping sulfuric acid solutions. A large-scale reconfiguration of the well field in 1996 led to a dramatic, yet temporary, increase in copper pounds, apparently due to changes in flowpaths. While the first reconfiguration was accomplished by means of hydrologic intuition, a question arose regarding the issue of whether subsequent reconfigurations supplemented with additional smaller scale characterization could ultimately lead to increased copper production. To study this question, two fifty-well sites were selected within the in-situ leach well field. Because in-situ leaching involves the movement of fluid within the subsurface, hydrology is a natural context in which to study the process. The desire to optimize well-to-well in-situ leaching for enhanced copper recovery through the fundamental understanding of important hydrologic mechanisms is the primary motivation for this dissertation. Hydrologic testing in San Manuel is inherently challenging due to the hydraulically dynamic environment. A hydraulic cross-hole testing procedure termed "Cyclic Pulse Testing" (CPT) was used to overcome this issue. Over 100 pressure responses obtained via CPT at the two test sites were examined by means of type curve analysis. The spatially distributed hydraulic parameters were analyzed within the framework of geostatistics. The kriged heterogeneous hydraulic conductivity fields were inputted into a numerical flow and transport model to study, along with other issues, the impact heterogeneity has upon the in-situ leaching process. A number of conclusions were reached based upon the investigation of the two test sites. Comparison between single-hole and cross-hole hydraulic tests revealed the probable presence of a low permeable skin surrounding the wells. By far, the most important hydrologic mechanism controlling the in-situ leaching process in San Manuel was the massively induced hydraulic background gradient, in places, on the order of 35°. Modeling revealed insignificant differences on the sweeping efficiency of the formation between heterogeneous and homogeneous simulations. However, due to the twodimensional nature of the collected data, additional three-dimensional information may lead to a different conclusion.en_US
dc.description.notehydrology collectionen_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.typetexten_US
dc.subjectHydrology.en_US
dc.subjectHydrology -- Arizona -- San Manuel.en_US
dc.subjectCopper -- Metallurgy.en_US
dc.subjectCopper mines and mining -- Arizona -- San Manuel.en_US
thesis.degree.namePh. D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineHydrology and Water Resourcesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.chairNeuman, Shlomoen_US
dc.contributor.committeememberBassett, Randyen_US
dc.contributor.committeememberOrr, Shlomoen_US
dc.contributor.committeememberPoulton, Maryen_US
dc.contributor.committeememberWang, Fei-Yueen_US
dc.identifier.oclc224594383en_US
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