Browsing by Subject "Platinum group"

Now showing 1 - 5 of 5
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    Characterization of Residue from the Pressure Oxidation Leaching of Bulk Copper-Nickel Sulfides from the Duluth Gabbro
    (University of Minnesota Duluth, 1999) Benner, Blair R; Niles, Harlan B
    The copper-nickel bearing material in the Duluth Gabbro represent a potentially significant reserve of copper and nickel with lesser amounts of cobalt and platinum group elements (PGEs). To help promote the development of this resource, the Coleraine Minerals Research Laboratory (CMRL) has conducted a series of investigations into methods of processing the material. A bulk sulfide flotation process followed by oxidation pressure leaching resulted in high extractions (>98 %) of the copper and nickel in the flotation concentrate. During the leaching, the iron in the flotation concentrate leaches and precipitates as either hematite (crystalline or amorphous) or as a basic iron sulfate (jarosite). The leaching should also leave the PGEs in the residue. If the hematite was present as a crystalline material, then if may be possible to recover a high grade iron product from the residue. If any PGE minerals could be found, then it may be possible to develop a method to recover and concentrate the PGEs. The Minnesota DNA through the Minerals Coordinating Committee funded the current study. The purpose of the research was to characterize the leach residue as to the iron bearing material and to determine if any PGE minerals could be found either by X-ray diffraction (XRD) or by electron microprobe analysis.
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    Finish Logging of Duluth Complex Drill Core (and a Reinterpretation of the Geology at the Mesaba (Babbitt) Deposit)
    (University of Minnesota Duluth, 2008) Severson, Mark J; Hauck, Steven A
    This project was undertaken with the objective to finish logging all drill holes from the basal contact zone of the Duluth Complex. Logging of Duluth Complex holes by Natural Resources Research Institute (NRRI) personnel began in 1989, when Severson and Hauck (1990) defined the igneous stratigraphy for most of the Partridge River intrusion (PRI). During the ensuing years the NRRI logged a total of 955 holes and defined igneous stratigraphic sections for several more intrusions of the Duluth Complex. As of 2005, a remainder of over 220 holes had yet to be logged. At the end of this project, 295 holes, which include some recently-drilled holes, were logged with about 20 holes still to be logged from the far eastern end of the Mesaba deposit. Lithologic logs for most of the holes that have been logged since 1989 are now available on the NRRI Geology Group’s website at www.nrri.umn.edu/egg/. The vast majority of holes that were logged for this project were from the Mesaba (Babbitt) Cu-Ni±PGE deposit, and thus, this report deals mostly with that deposit. A result of logging a large number of holes at the Mesaba deposit indicates that most of the deposit does not exhibit a stratigraphic package that has been recognized within the nearby Partridge River intrusion. This suggests that most of the deposit is situated within another sub-intrusion, informally called the Bathtub intrusion (BTI). The BTI appears to have been fed by a vent in the Grano Fault area on the east side of the Mesaba deposit. Forty-two cross-sections from the Mesaba deposit, showing the geology in over 450 surface holes, are presented in this report. Another 26 cross-sections, showing the geology in 219 underground holes, are also presented for the Local Boy ore zone of the Mesaba deposit. All of these cross-sections are utilized to define the igneous stratigraphy of the BTI and adjacent PRI at the deposit. All publically-available drill holes have now been logged from the Dunka Pit Cu-Ni deposit located in the South Kawishiwi intrusion (SKI). Nineteen cross-sections through the deposit are presented in this report. These cross-sections show the geology, potential Cu-Ni ore zones in the holes, and the down dip extent of potential mineable zones of the Biwabik Iron Formation at depth. Additional areas in the SKI where holes were logged for this project include the Maturi, Spruce Road, and Nokomis deposits. Cross-sections and hung stratigraphic sections are presented, and they show the geology intersected in these newly-logged holes relative to previously-logged holes. Drill holes from two Oxide-bearing Ultramafic Intrusions (OUI) were also logged for this investigation. These logs include ten holes from the Longnose deposit and ten holes from the Water Hen deposit. Six cross-sections through the Longnose deposit are presented in this report. In summary, the holes logged in this investigation have added greatly to our understanding of the geology of basal portions of the Duluth Complex. In some cases, the previously defined igneous stratigraphic sections for the various intrusions have held up remarkably well as additional holes are drilled and logged. Of course, there are always some exceptions to the rule. In other cases, e.g., the Mesaba deposit, as more holes were logged and/or drilled, the igneous stratigraphy had to be modified in order to explain differences in a group of holes that were situated in the BTI versus the nearby PRI. This change serves as an example that definition of igneous units, and modes of mineralization, in the Duluth Complex is an iterative process and has to be continuously refined as more data, in the form of new drill holes, are generated.
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    Geology and Cr-PGE Mineralization of the Birch Lake Area, South Kawishiwi Intrusion, Duluth Complex
    (University of Minnesota Duluth, 1997) Hauck, Steven A; Severson, Mark J; Ripley, Edward M; Goldberg, Steven A; Alapieti, Tuomo
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    Igneous Stratigraphy and Mineralization in the Basal Portion of the Partridge River Intrusion, Duluth Complex, Allen Quadrangle, Minnesota
    (University of Minnesota Duluth, 1997-12) Severson, Mark J; Hauck, Steven A
    Geologic mapping of the igneous rocks of the Partridge River intrusion (PRI) within the Allen Quadrangle was conducted during the 1996-1997 period by Severson and Miller (1997). In addition to the surface geology, drill holes were logged in order to gain a better understanding of the third-dimensional geology and Cu-Ni mineralization of the quadrangle. Drill hole correlations of igneous units, along with cross-sections and a discussion of Cu-Ni±PGE enriched zones, are presented in this report. Detailed logging of drill core from over 400 drill holes indicates that there are at least seven major igneous units (Units I through VII) within the basal 3,000 feet of the PRI. These units, starting with Unit I at the base, are described in Severson and Hauck (1990) and are reiterated herein for drill holes within the Allen Quadrangle. Also present within the quadrangle and described in this report are late plug-like bodies of Oxide-bearing Ultramafic Intrusions (OUI), a Keweenawan sill within the Biwabik Iron-Formation (K-Sill), and a small Keweenawan(?) intrusive within the Archean rocks near a major fault zone. Establishment of an igneous stratigraphy for the PRI provides a framework that can be used to determine the nature and location of fault offsets between drill holes. The tenor of Cu-Ni mineralization is often locally increased along some of these faults. Fault zones, with or without increased mineralization, that are discussed in this report include faults in the Wetlegs Cu-Ni deposit, faults in the Wyman Creek Cu-Ni deposit, the Siphon Fault, and the Donora Fault. Many of these fault zones are depicted on the cross-sections that accompany this report. Enrichments in Platinum Group Elements (PGE) occur at several stratabound horizons within the Allen Quadrangle (using an arbitrary cutoff of >90 ppb Pd). All of these PGE-enriched horizons are present in sulfide-bearing troctolitic rocks that are positioned immediately below, and in some cases within, laterally continuous ultramafic layers. However, the overall Pd content in some of the horizons shows a definite decrease in an east-to-west direction. This trend suggests that as the magma of the PRI was intruded, in an east-to-west direction(?), it became progressively impoverished with respect to PGEs.
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    Platinum Group Elements (PGEs) and Platinum Group Minerals (PGMs) in the Duluth Complex
    (University of Minnesota Duluth, 2003) Severson, Mark J; Hauck, Steven A