Minerals & Metallurgy

Persistent link for this collectionhttps://hdl.handle.net/11299/187105

Please note: This collection contains a variety of Reports of Investigations, Technical Reports, and Technical Summary Reports on a particular subject. For all Reports of Investigations, Technical Reports, or Technical Summary Reports, please see the following collections:

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An Addendum to: Geology and Sulfide Content of Archean Rocks Along Two Proposed Highway 169 Relocations to the North of Sixmile Lake, St. Louis County, Northeastern Minnesota and Geologic Investigations in the Armstrong Lake Area
(University of Minnesota Duluth, 2012) Severson, Mark J; Heine, John J
This report summarizes the geochemical results pertaining to the sulfur contents of rock samples collected in the Sixmile Lake area, and thusly, serves as an addendum to a previous report by Severson and Heine (2010). Geologic mapping in the Sixmile Lake area was initiated at the request of the Minnesota Department of Transportation (Mn/DOT) and concentrated on areas where Highway 169 could potentially be re-routed. The second purpose of this addendum is to provide the appropriate GIS-related shape files that were omitted from the initial report by Severson and Heine (2010). These shape files have been finalized and are provided in this report. In addition, reconnaissance geologic mapping took place along other Highway 169 relocations in the Armstrong Lake/McComber Mine area. The results of that endeavor are provided in this report. The results of sulfur analyses for samples collected from the Sixmile Lake area show that most of the samples with ≥ 0.15% analyzed sulfur contents were correctly mapped as “anomalous sulfide zones” by Severson and Heine (2010). However, there were several instances where the visually-estimated pyrite contents did not compare well with the actual sulfur contents due to a “nugget effect” variation in the third dimension. This “nugget effect” variability is troublesome and suggests that some form of drilling should take place in the areas of future road cuts in order to obtain more representative S% values. Examination of rock exposures and recent drilling of the iron-formation in the vicinity of Shaft #2 in the McComber Mine area indicates that pyrite is present in much higher amounts when compared to Sixmile Lake. Thus, additional drilling will be needed in the McComber Mine/Shaft #2 subarea, and possibly in the Clear Lake subarea, in order to obtain a better understanding of the amount of pyrite present.
Bedrock Geologic Map of the Duluth Complex in the Northern South Kawishiwi Intrusion and Surrounding Area, Lake and St. Louis Counties, Minnesota
(University of Minnesota Duluth, 2008-05) Peterson, Dean M
This map is the result of numerous investigations by the author and many others over the last 8 years of the South Kawishiwi intrusion (SKI) and it's contained Cu-Ni-PGE mineralization. Detailed geological mapping evolved from a study of the Nickel Lake Macrodike (NLM) into a comprehensive geologic mapping and compilation project (104,000 acres) to answer some of the fundamental questions on the origin of the extensive known and undiscovered Cu-Ni-PGE mineralization in the northern portion of the SKI. Such an increase in scope is needed due to the economic significance of the published resource estimates (>$146 billion in contained metal) from this area. To date, nearly 15,000 outcrops, 1,400 structural measurements, geology and geochemistry from 773 drill holes totaling over 845,000 feet of core, and 12,500,000 meters of elevated contour lines (see Digital Topography image below) have been integrated into the comprehensive GIS database. The map units of the SKI depicted on this map sheet differ from previous maps from the area, in that the author has consulted with numerous company geologists and defined map units based on what industry geologists use to define rock masses encountered in drill core. This new map includes geology from each of the major lithologic units in the area, namely the Late Archean Giants Range batholith, the Paleoproterozoic Biwabik Iron and Virginia Formations, and the Anorthositic Series, Bald Eagle Intrusion, SKI, and the NLM of the Mesoproterozoic Duluth Complex. There are only a few faults depicted on the map, and literally hundreds of kilometers of linear topographic features that remain to be investigated in detail (see Digital Topography image below). However, little obvious offset of rock units have been observed along these features where investigated in detail, thus the author has purposely not drawn many faults on the map. One main new insight of this recently completed compilation is the recognition that the northeastern extent of the SKI is not a shallowly dipping sill but rather a southwest trending, inclined funnel-like body. Such an interpretation leads to the conclusion that the eastern contact of the SKI, which previously was interpreted as the top of the intrusion, is a basal contact, and thus has great potential for hosting Cu-Ni-PGE mineralization at its base. Understanding the origin of mineralized zones is the goal of all economic geologists, and in magmatic ore systems like the SKI, one must try to imagine the magmatic processes that culminated in the formation of the ores and surrounding rocks, i.e. how did the SKI form? Did the magmas intrude as crystal-laden slurries? Are the "Open" and "Confined" styles of mineralization defined by Peterson (2001) true mappable units? Such thoughts are the basis upon which the author began the quest to complete this map sheet. The author has inserted a number of inset maps and figures for the reader to review and ponder about the possible types of magmatic prosesses that occurred in the area (now depicted on this map sheet) 1.1 billion years ago. It is hoped that careful review of the bedrock geologic map and inset figures will give the reader and user of the map new geologic insight and ideas for future mineral exploration programs and scientific study.
Bedrock Geology Map of the Nickel Lake Macrodike and Adjacent Areas: Lake County, Northeastern Minnesota
(University of Minnesota Duluth, 2006-11) Peterson, Dean M; Albers, Paul B; White, Chris R
This map is the first of what is hoped (contingent on funding) to be a series of new detailed bedrock geology maps of the marginal zone of the South Kawishiwi Intrusion by the University of Minnesota Duluth's Natural Resources Research Institute (see Peterson, 2006). Such mapping will form the basis for continued exploration for Cu-Ni-PGE mineralization as well create the geologic base upon which environmental review associated with exploitation of such mineralization can be built. Recent detailed mapping at a scale of 1:5,000 by the authors was conducted west and south of the Boundary Waters Canoe Area Wilderness (BWCAW). Nearly 1,000 outcrops along approximately 100 kilometers of field traverses were examined to identify and confirm the internal lithologic variability, contact relationships, and structure of the Nickel Lake Macrodike between the BWCAW and Omaday Lake. The authors wish to acknowledge Dr. Paul Weiblen (emeritus professor of geology at the University of Minnesota) for his keen insight of the geology of the area and Dr. George Hudak and undergraduate student Jeremiah Gowey of the University of Wisconsin Oshkosh for assistance in mapping outcrops around and south of Omaday Lake. Additional reconnaissance mapping in early November by the senior author was conducted to field check compiled outcrop locations depicted on the 1957 INCO map of the Spruce Road Deposit and the 1968 Hanna Mining map of the South Filson Creek Deposit (both of which are publically available in the DNR archive at Hibbing, Minnesota). The reconnaissance mapping confirmed the location of gossaneous Cu-Ni bearing INCO outcrops and reconfirmed the outstanding field mapping of all types of Duluth Complex rocks by Hanna Mining Company geologists of the late 1960s (see figure of "Sources of Information"). This map has been built upon (in the areas surrounding depicted outcrops and historic drill holes) the 1966 map of the Gabbro Lake 15' quadrangle by Green et al. (Minnesota Geological Survey Miscellaneous Map M-2), which because of its quality has been the geologic foundation for this area for 40 years. The reader of this map should compare the author's interpretation of the bedrock geology to that depicted on M-2, which will undoubtedly highlight the need for continued detailed mapping of the marginal zone of the South Kawishiwi Intrusion (which was not the purpose of map M-2), especially in light of the greatly increased interest in the potential for exploiting the vast resources of Cu-Ni-PGE mineralization enclosed within these rocks. The Nickel Lake Macrodike is lithologically and structurally related to the South Kawishiwi Intrusion and the known Cu-Ni-PGE deposits of Birch Lake, Maturi, Maturi Extension, Spruce Road, and South Filson Creek. The citation for this map includes the caveat "Version 1", which points out the fact that the authors believe that more detailed geologic mapping and analytical studies (no petrography or geochemical analyses of recently collected samples has been completed) are needed to truly understand what the bedrock geology enclosed within the boundaries of this map sheet (and the area to the west-southwest) really is (ie. we've only begun to scratch the surface). This map and all associated GIS data (in ArcView 3.2 format) can be obtained online at http://www.nrri.umn.edu/egg/publicationlist.html.
Bedrock Geology, Sample Location, and Property Position Maps of the West Birch Lake Area, South Kawishiwi Intrusion, Duluth Complex, Lake and St. Louis Counties, Northeastern Minnesota
(University of Minnesota Duluth, 2002-04) Peterson, Dean M; Marma, John; Brown, Philip
This map (NRRI/MAP-2002/02) is the outcome of eight field days mapping and sampling in the area by the senior author. The initial impetus for this mapping was to try to define Duluth Complex induced contact-metamorphic zonation in the footwall Giants Range batholith, and to relate this to Cu-rich mineralization in these rocks. Research into footwall Cu-rich mineralization continues, and will be published in the future. However, the discovery of large expanses of Cu-Ni mineralized rock in the basal zone of the South Kawishiwi, in an essentially unmapped area, lead to this preliminary map (Figure 1). The geologic map represents the initial interpretaton of the bedrock geology of the basal zone of the South Kawishiwi Intrusion, based on mapped outcrops, subcrops, and glacial materials (float). In addition, geologic units intersected in drill holes have been projected updip to the surface. The faults depicted on the map are interpreted from aeromagnetic data, steepening of the dip of the basal contact of the Duluth Complex, and topographic lineaments. The location and simplified regional geology encompassing the map area is depicted in Figure 4. The lithologic legend of the geology map is simplified into the intrusive stratigraphy of the South Kawishiwi Intrusion first defined by Severson (1994). Readers interested in detailed descriptions of the regional South Kawishiwi Intrusion stratigraphy are referred to that work. Cu-Ni-PGE mineralization is largely confined to the basal stratigraphic units of the intrusion (units BAN, BH, and U3), and on the ground is largely represented by knob-like outcrops, and large expanses of rusty, gossaneous boulder fields (subcrops). Old test pit dumps (circa 1890 ?) into the Biwabik Iron Formation are common in the southern portion of the map, and occur in areas of anomalous magnetic field properties. Seventy-five rock samples (Figure 2) were collected in the area (described in Table 1), and Dr. Philip Brown and John Marma (Department of Geology, University of Wisconsin - Madison) provided the funding for the base- and precious-metal analyses of twenty of these samples (presented in Table 2). Check assays for anomalous samples were analyzed by ALS Chemex labs from the original pulps and rejects (Table 2). Assay data for the majority of the drill holes in the map area have been compiled by Peterson (1997), which includes > 60,000 geochemical analyses for drill holes throughout the Duluth Complex. The smaller-scale property position map (Figure 3) depicts the current mineral lease holders in the area, and should only be viewed as a "snapshot" of the mineral land positions at the date of this map. Detailed geologic mapping in the area, including additional geochemical analyses, has been approved from the Permanent University Trust Fund, and will be completed during the 2002 field season.
Bench Scale Tests to Separate Mercury from Wet‐Scrubber Solids from Taconite Plants
(University of Minnesota Duluth, 2007) Benner, Blair R
Bench-Scale Evaluation of Hydrometallurgical Processing to Recover Vanadium from Minnesota Titanium Resources
(University of Minnesota Duluth, 2021-10) Hudak, George J; Monson Geerts, Stephen D; Chen, Jonathan; Halim, A; Sridhar, Ram; Lakshmanan, V.I.
Vanadium is the twenty-second most abundant element in the Earth’s crust and occurs as a major component (greater than 10% by weight) in 156 minerals that occur in a variety of mineral deposit types. These mineral deposit types are globally distributed and include vanidiferous titanomagnetite (VTM) deposits, sandstone hosted (SSV) deposits, shale-hosted vanadium deposits, and vanadate deposits (Kelley et al., 2017). The Duluth Complex of northeastern Minnesota contains a variety of base and precious metal resources (Fig. 1), including a number of Mesoproterozoic-age copper-nickel-cobalt-platinum group element (Cu-Ni-Co-PGE) resources as well as a series of younger, Mesoproterozoic-age oxide ultramafic intrusions (OUIs) that contain both titanium and vanadium resources (Minnesota Minerals Coordinating Committee, 2016; Table 1). Vanadium deposits within OUI deposits associated with the Duluth Complex are classified as vanadiferous titanomagnetite (VTM-type) vanadium deposits by the United States Geological Survey (USGS; Kelley et al., 2017). World resources of vanadium are greater than 63 million tons; however, vanadium concentrations generally constitute less than 2% of the deposit host rock (Polyak, 2021). In 2020, mine production of vanadium worldwide was approximately 94,800 tons, with the United States (0.2%), Brazil (7.7%), China (61.6%), Russia (21.0%) and South Africa (9.5%) being the major producers (Polyak, 2021). Vanadium is utilized in a variety of applications. Its principal use is for the production of metal alloys such as high-strength steel and alloys utilized in the aerospace industry. It is also used for catalysts in the chemical industry, in ceramics, in glasses, and as a pigment (Schulz et al., 2017). Production of carbon-, full-alloy-, and high-strength low-alloy steels accounted for 18%, 45%, and 33% of domestic consumption in 2020, respectively (Polyak, 2021). The emerging need for large-scale “green” electrical energy storage associated with wind, solar, and other intermittent power sources may result in major utilization of vanadium in the form of vanadium redox-flow batteries (VFRB) which take advantage of the various electrical valencies of vanadium cations (https://energystorage.org/why-energy-storage/technologies/vanadium-redox-vrb-flow-batteries/). As well, vanadium is utilized in other battery applications, including lithium-vanadium-phosphate batteries and lithium ion batteries (Schulz et al., 2017). Commercial products resulting from processing of vanadium ores include ferrovanadium (FeV, an iron-vanadium alloy), which is used in the production of steel alloys, vanadium pentoxide (V2O5), which is commonly utilized as a chemical catalyst, and ammonium metavanadate (NH4VO3), a precursor for the production of vanadium pentoxide, catalysts, and analytical reagents (Pérez-Benítez and Bernès, 2018). In 2020, U.S. net import reliance for vanadium was 96%, with major import sources being Brazil, South Africa, Austria and Canada (United States Geological Survey, 2021). A large portion of domestic needs could be met by domestic resources and secondary recovery processes (Polyak, 2021). As a result of this large net import reliance, vanadium is considered a critical mineral resource in the United States (Executive Order 13817 “Federal Strategy to Ensure Reliable Supplies of Critical Metals”; Schulz et al., 2017; Nassar and Fortier, 2021). Results of recent hydrometallurgical experiments conducted by Process Research Ortech (PRO) and the Natural Resources Research Institute (NRRI) indicate that vanadium concentrations continue to increase within titanium raffinate as recycling of organics takes place in a closed-system hydrometallurgical circuit developed to produce TiO2 and Fe2O3 products from the Longnose OUI mineral deposit (Hudak et al., 2021). The research described in this report discusses collaborative research conducted by PRO and NRRI to evaluate whether or not high-purity vanadium materials (specifically ammonium metavanadate and vanadium pentoxide) could be produced as by-products of hydrometallurgical processing of the titanium raffinate solutions resulting from continuous pilot-scale hydrometallurgical processing of Longnose mineral concentrates (Hudak et al., 2021).
A Bibliography of Published Research in Minnesota Related to the State’s Mineral Potential: April 2020
(University of Minnesota Duluth, 2020-04) Hudak, George J
The United States Geological Survey (USGS) provided funding via the FY 2019 National Geological and Geophysical Data Preservation Program (NGGDPP) for the project “Updated Minnesota Data Inventory: Preservation of Pillsbury Hall Rock Collections with Associated Additional Documentation: Assembly of Mineral Potential Related Information.” The three priority components of this project were as follows: • Priority 1: Collection Inventory and metadata record revision in the National Digital Catalog; • Priority 2: Preservation of Pillsbury Hall Rock collections with associated and additional documentation; and • Priority 3: Assemble information that supports identification of critical mineral resources in Minnesota. As part of Priority 3, the Natural Resources Research Institute (NRRI) was subcontracted by the Minnesota Geological Survey to prepare a bibliography briefly describing published research specific to Minnesota that supports inference of mineral potential on the basis of geological mapping, and a bibliography listing references for published literature on this topic. The NRRI provided matching funding to complete this work from the NRRI University of Minnesota Permanent University Trust Fund. The USGS has recently developed a new minerals system approach for critical minerals inventory, research and assessment (https://www.usgs.gov/energy-and-minerals/mineral-resourcesprogram/ science/systems-approach-critical-minerals-inventory?qt-science_center_objects=0#qtscience_ center_objects; Hostra, 2019). The following bibliography is organized utilizing this minerals system classification scheme. As Minnesota has a preserved geologic history that spans greater than 3.6 billion years, and as a wide variety of geological processes have been active over this geological history, mineral potential exists in many of the mineral systems, including Chemical Weathering, Placer, Meteoric Recharge, Marine Chemocline, Volcanogenic Seafloor, Orogenic, Metamorphic, IOA-IOCG, and Mafic Magmatic. As well, a short bibliography of potential By-Products/Recycling resources has been included with this bibliography.
A Bibliography of Published Research in Minnesota Related to the State’s Mineral Potential: June 2022
(University of Minnesota Duluth, 2022-06) Hudak, George J
The Minnesota Geological Survey (MGS) was provided funding from the United States Geological Survey (USGS) via the FY 2021 National Geological and Geophysical Data Preservation Program for the “FY21 Minnesota Geological and Geophysical Data Preservation Program.” The program included two priorities that collectively involved 11 separate Projects: Priority 1: Data Preservation • Project 1: Preservation of MGS Field Data • Project 2: Preservation of MGS Cuttings • Project 3: Minnesota Drill Core Library Inventory, Phase I • Project 4: Data Preservation Workshop Priority 2: Mineral Potential-Related Information • Project 5: State Compilation of Mineral Deposits / Districts • Project 6: Contribute Data to USGS Map Compilation of Focus Areas • Projects 7 and 8: State Compilation of Borehole Data with Metadata to NDC • Project 9: Update Geologic Map Database • Project 10: USGS Critical Minerals Workshop • Project 11: Strategic Plan for Critical Minerals As a Component of Priority 2, Project 6, “Contribute Data to USGS Map Compilation of Focus Areas,” the Natural Resources Research Institute (NRRI) was subcontracted by the Minnesota Geological Survey (MGS) to prepare a bibliography indicating published geological, geochemical, and geophysical research specific to Minnesota that supports inference of Mineral potential. Matching funding was provided from the NRRI University of Minnesota Permanent University Trust Fund to complete this work. The publications that form the basis of this bibliography are in NRRI Technical Summary Report “Duluth Complex Geological Bibliography” (Hauck, 2017), “A Bibliography of Published Research in Minnesota Related to the State’s Mineral Potential” (Hudak, 2020), and “Minnesota Data Preservation Report for 2019/2020: Updated Data Inventory, Preservation of Pillsbury Hall Rock Collections and Documentation, Assembly of Mineral Potential Related Information (Thorleifson, 2020). Matching funding was provided from the NRRI University of Minnesota Permanent University Trust Fund to complete this work. The following bibliography has been organized utilizing the USGS Mineral Systems approach for critical minerals inventory, research and assessment (Hofstra, 2019; Hofstra and Kreiner, 2020). As Minnesota has a preserved Geologic history that spans greater than 3.6 billion years, a wide variety of geological Processes encompassing a number of Mineral Systems have been active within the State. These include Chemical Weathering, Placer, Meteoric Recharge, Marine Chemocline, Volcanogenic Seafloor, Orogenic, Metamorphic, IOA-IOCG, and Mafic Magmatic. This bibliography includes references specific to each of these Mineral Systems, as well as a list of references Related to potential by-products, recycling, and carbon Mineralization publications focused on Minnesota resources.
A Bibliography of Published Research in Minnesota Related to the State’s Mineral Potential: June 2023
(University of Minnesota Duluth, 2023-06) Hudak, George J
The Minnesota Geological Survey (MGS) was provided funding from the United States Geological Survey (USGS) via the FY 2022 National Geological and Geophysical Data Preservation Program for the “FY22 Minnesota Geological and Geophysical Data Preservation Program.” The program included two priorities that collectively involved 10 separate projects: Priority 1: Data Preservation • Project 1: Preservation of MGS Field Data • Project 2: Seismic Database and Geophysical Compilation • Project 3: Preservation of MGS Cuttings, Phase Three • Project 4: Minnesota Drill Core Library Inventory, Phase Two • Project 5: Data Preservation Workshop Priority 2: Mineral Potential-Related Information • Project 6: State Compilation of Mineral Deposits / Districts • Project 7: Mapping for USGS Compilation of Earth MRI Focus Areas • Projects 8: State Compilation of Borehole Data • Project 9: Prepare For, and Attend, and Follow-Up Earth MRI Workshop • Project 10: Preservation Plan for Critical Minerals As a Component of Priority 2, Project 7, “Mapping for USGS Compilation of Earth MRI Focus Areas,” the Natural Resources Research Institute (NRRI) was subcontracted by the Minnesota Geological Survey (MGS) to prepare a bibliography indicating published geological, geochemical, and geophysical research specific to Minnesota that supports inference of Mineral potential. Matching funding was provided from the NRRI University of Minnesota Permanent University Trust Fund to complete this work. The publications that form the basis of this bibliography are included in NRRI Technical Summary Report “Duluth Complex Geological Bibliography” (Hauck, 2017), “A Bibliography of Published Research in Minnesota Related to the State’s Mineral Potential” (Hudak, 2020), “Minnesota Data Preservation Report for 2019/2020: Updated Data Inventory, Preservation of Pillsbury Hall Rock Collections and Documentation, Assembly of Mineral Potential Related Information” (Thorleifson, 2020), and “A Bibliography of Published Research in Minnesota Related to the State’s Mineral Potential: June 2022” (Hudak, 2022). The following bibliography has been organized utilizing the USGS Mineral Systems approach for critical minerals inventory, research and assessment (Hofstra, 2019; Hofstra and Kreiner, 2020). As Minnesota has a preserved geologic history that spans greater than 3.6 billion years, a wide variety of geological processes encompassing several mineral systems have been active within the State. These include Chemical Weathering, Placer, Meteoric Recharge, Marine Chemocline, Volcanogenic Seafloor, Orogenic, Metamorphic, IOA-IOCG, and Mafic Magmatic. This bibliography includes references specific to each of these mineral systems, as well as a list of references related to potential by-products, recycling, and carbon mineralization publications focused on—and/or referencing—Minnesota resources.
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.
Characterization of the Kaolin Occurrences in Northern and Central Minnesota
(University of Minnesota Duluth, 1998) Heine, John J; Patelke, Richard L; Oreskovich, Julie A
Kaolin mining and exploration in Minnesota has been concentrated in the Minnesota River Valley, in the south-central part of the state. Potential exists for kaolins in northern and central Minnesota. Using the resources of the Minnesota Department of Natural Resources Drill Core Repository, over 1,250 drill logs were reviewed for references to kaolin bearing materials. This process resulted in 170 drill holes that contained references to kaolin bearing materials. Examination of these drill holes resulted in the selection of 60 drill holes containing kaolinitic materials for detailed logging. Detailed logging resulted in the collection of 287 samples from 40 drill holes. All samples were run for particle size analysis, and 27 selected samples were run for geochemistry. Many regions in the study area show potential for kaolin clay exploration. All areas sampled have favorable geochemistry and particle size analyses for current industrial clay uses, which include brick manufacturing, ceramics, and portland cement production. The areas with the greatest potential are Cass, Crow Wing, Stearns, Chippewa, Lac Qui Parle, and Pope Counties. Other possible uses for these clays include, refractory materials, fillers and pigments for industrial and agricultural applications, and coating and fillers for the paper industry. Exploration for kaolin deposits may be hindered by the lack of outcrop and thick overburden in some of these areas. The use of geophysical techniques, coupled with the examination of other drill holes and water well log data, may aid in the location of areas of further interest for exploration companies.
Chemistry, Mineralogy & Liberation Characteristics of Samples of EVTAC Concentrator Unit Operations
(University of Minnesota Duluth, 2005) Niles, Harlan B
Minnesota taconite operations frequently encounter quality problems due to chemical-mineralogical variations in crude ore blends. Mine personnel have expressed interest in determining ore blend behaviors in unit operations of concentrators. This knowledge could assist in providing ore blends that produce more uniform and desirable final concentrates. The behavior of ores in intermediate concentrator stages may also help concentrator operators to adjust units to produce optimum results. A project proposal submitted to the Permanent University Trust Fund (PUTF) to determine chemistry, mineralogy, and indicated magnetite liberation for samples of unit operations of two EVTAC ore blends was approved. Feed, concentrate, and tailing samples from concentrator unit operations that represented two crude ore blends were received by the Coleraine Minerals Research Laboratory (CMRL) in 2001 and 2002. They were designated Set 1 and Set 2, respectively. The samples were dried, mixed, and split into portions for "As Is" Davis tube magnetic separations and other splits to be pulverized for chemical analyses and for x-ray diffraction. Chemistry was run at the CMRL and x-ray diffraction patterns were run at the University of Minnesota Shepherd Laboratory in Minneapolis. Mineral percentages in each sample were calculated from the chemical analyses on a spreadsheet in a "Quattro Pro for Windows" computer program after examining x-ray patterns to determine the minerals that were present. The spreadsheet was adjusted to comprehend minerals present and their chemical compositions, and so that the sum of mineral percentages in a sample was within 0.50 percent of the chemistry total oxides (near 100 percent). The results of “As Is" Davis tube separations are given in Table I. It shows magnetic weight recoveries and concentrate iron and silica percentages and provides an indication of the progressively improved magnetite liberation through the concentrator operations. It also shows that liberation in sample Set 2 was somewhat better than in Set 1, and, when compared to the sample chemical analyses in Table 2, separation efficiencies in concentrator units are demonstrated. Calculated mineral percentages in cobber feed samples showed that total silicates were nearly equal in Sets 1 and 2, that the hematite percentage was considerably higher in Set 1, and that total carbonate was higher in Set 2. In the final concentrates, most hematite and silicates had been rejected from both sets, but the total carbonate from Set 2 was 3.6 percent, about double that for Set 1. A set of bar graphs was made for each unit operation, which shows percentages of each mineral in the feed, concentrate and tailing. They illustrate the recovery and rejection of each mineral in each concentrator operation. Company personnel may therefore distinguish the effectiveness of each unit in recovering and rejecting particular gangue minerals.
A Comparative Economic Analysis of the Impact of Taxes and Royalties on Potential Non-Ferrous Mining Projects: Minnesota’s Rank - Nationally and Internationally - at the Start of the 21st Century: Interim Report
(University of Minnesota Duluth, 2002) Zanko, Lawrence M
There still exists in the non-ferrous minerals industry a perception that Minnesota is a hightax state, making it unattractive for hard rock mineral investment. This perception is reflected by the most recent industry survey performed by the Canada-based Fraser Institute, in which Minnesota was ranked near the bottom in the categories of: 1) mineral potential, 2) policy potential, and 3) investment attractiveness, relative to several U.S. states, Canadian provinces, and most other foreign countries. To address this negative perception issue, an up-to-date, rigorous, and objective comparative economic analysis is being performed to quantify the economic impact that Minnesota’s current tax and royalty policies have on potential non-ferrous mining projects. This ongoing analysis uses hypothetical mining project models that are patterned after realistic mining operations worldwide, with an emphasis on Cu ± Ni ± PGE and PGE deposits, given Minnesota’s widely acknowledged mineral potential for both. Both underground and open pit mining methods are addressed in what will ultimately be a multi-state (Minnesota, Wisconsin, Montana, Arizona, Alaska, and Nevada) and multi-province and country (Ontario, British Columbia, Western Australia, Chile, and Sweden) comparison, against which the tax and royalty policies of each regime are applied. Economic measurement tools - like discounted cash flow rate of return (DCFROR) and sensitivity analyses - are used to provide quantitative results. Multiple economic scenarios will provide a range of outcomes that can be evaluated by both the private and public sector. For example, the specific example presented herein shows that Minnesota compares well with the Canadian province of Ontario with respect to mining taxes and royalties.
A Comparative Economic Analysis of the Impact of Taxes and Royalties on Potential Non-Ferrous Mining Projects: Minnesota’s Rank – Nationally and Internationally – at the Start of the 21st Century [Part I]
(University of Minnesota Duluth, 2007) Zanko, Lawrence M; Peterman, Jill
Comparative Geology, Stratigraphy, and Lithogeochemistry of the Five Mile Lake, Quartz Hill, and Skeleton Lake VMS Occurrences, Western Vermilion District, NE Minnesota
(University of Minnesota Duluth, 2002-12) Hudak, George J; Heine, John J; Newkirk, Trent; Odette, Jason; Hauck, Steven A
Comparison of One and Two Stage High Pressure Rolls Grinding followed by Ball Milling with Conventional Rod and Ball Milling
(University of Minnesota Duluth, 1999) Benner, Blair R
With the development of the autogenous wear surface, the high pressure roller press (HPR) is receiving interest from the mineral industry. Previous work by the Coleraine Laboratory had indicated energy saving using a single stage of HPR compared to rod milling and an energy saving using 2 stage HPR compared to single stage HPR. The purpose of this study was to compare three flowsheets using the same feed and producing a final size of about 85 percent passing 270 mesh. The flowsheets were as follows: (1) Rod mill followed by wet magnetic separation with ball mill grinding of the magnetic concentrate; (2) HPR closed with a 3 mesh screen followed by wet magnetic separation of the screen undersize and ball milling of the magnetic concentrate; (3) HPR closed with a 3 mesh screen with the screen undersize being upgraded by dry magnetic separation followed by open circuit HPR on the magnetic concentrate with wet magnetic separation of the HPR product and ball milling of the wet magnetic concentrate. The test work indicated that the single stage HPR required 27.25 kWh/It of new feed compared to 34.0 kWh/It for the rod mill to produce an 85 percent passing 270 mesh ball mill discharge. The two stage HPR flowsheet was even more energy efficient, requiring only 23.29 kWh/It of new feed. With the single stage HPR, the energy savings appears to be only in the coarse grinding. The ball mill grindability, as measured by the operating work index, was essentially the same for the rod mill and HPR magnetic concentrates. The two stage HPR resulted in energy savings in both the coarse grinding and in the ball milling. The operating work index for the ball mill portion only was 23.5 kWh/It of ball mill feed for the two stage flowsheet compared to about 29 kWh/It for the other two flow sheets. Davis tube tests on the ball mill discharges suggest that there is a liberation benefit associated with the two stage HPR flowsheet, but not with the single stage HPR flowsheet.
Compile and Make Digital the Lithologies for all NRRI Drill Logs, with Emphasis on the Duluth Complex Drill Holes (An Addendum to an Earlier NRRI Database)
(University of Minnesota Duluth, 2009) Severson, Mark J; Oreskovich, Julie A; Patelke, Marsha Meinders
This report and associated databases are updates on many of the holes that have been recently logged by the Natural Resources Research Institute (NRRI) in the Keweenawan Duluth Complex, the Paleoproterozoic Biwabik Iron Formation of the Mesabi Iron Range, and the Archean Deer Lake Complex of northeastern Itasca County, Minnesota. The main emphasis of this project was to update some of the databases that were presented in an earlier NRRI report (Patelke, 2003) with regard to lithologies in Duluth Complex drill holes that were logged by the NRRI since 2003 (and discussed in Severson and Hauck, 2008). To date, all of the publically available drill holes (except for around 30 drill holes) have now been logged in the Duluth Complex by the NRRI. These 30 holes are all that are missing from either the databases in this report or the databases in Patelke (2003). It is strongly suggested that the databases herein be combined, at the user’s discretion, with corresponding databases in Patelke (2003) in order to make an all- encompassing database for lithologies for all NRRI logged drill holes in the Duluth Complex. A secondary goal of this project was to present a header file database for all the holes that were recently drilled in the Duluth Complex (post-2003). Most of these holes are not yet publically available, but data regarding drill hole locations can be gleaned from abandonment files. Combining Duluth Complex header files in this report with the similar header file in Patelke (2003) could provide an all-encompassing database of locations for all of the holes drilled to date in the Duluth Complex (pre-2010 data). This combining of the data is left to the user’s discretion. Lastly, additional goals of this project (time permitting) were to present lithologic databases for all holes logged by the NRRI in the Mesabi Iron Range and, to a much lesser extent, holes logged by the NRRI in the Deer Lake Complex. The database for the Mesabi Iron Range contains information for almost 300 drill holes (over 5,947 lines of lithologic data) in regard to the lithologic picks pertaining to informal members and submembers of the iron-formation. The data in this file is about 80% complete in that not all of the iron-formation submembers are presented for holes drilled at the Keetac Taconite mine or in the Coleraine, MN, area (the latter holes are discussed in Zanko et al., 2003).
Continuous Pilot-Scale Demonstration of Ilmenite Processing Technology
(University of Minnesota Duluth, 2021-05) Hudak, George J; Rao, Shashi; Peterson, Dean M; Chen, Jonathan; Lakshmanan, V.I.; Sridhar, Ram; Gluck, Eugen
Control of Residual Sulfides in Flotation Tailings of Cu-Ni Duluth Complex via Grinding Media Selection
(University of Minnesota Duluth, 2001) Iwasaki, Iwao
The effects of grinding media chemistries on ball wear and flotation were compared by grinding a Cu-Ni bearing Duluth Complex sample using forged steel and 27% Cr cast iron balls under nitrogen, air and oxygen atmospheres. Both types of balls increased their wear in air and oxygen atmospheres, but Cr balls wore only one-third as much as forged steel balls. The wear increased roughly in proportion to the oxygen content of the mill atmosphere. Flotation recoveries of sulfide minerals were adversely affected when the sample was ground in a nitrogen atmosphere. Residual sulfur in flotation tailings ground using both types of grinding balls under an air or oxygen atmosphere was lowered to about 0.15%, with Cr balls producing somewhat lower sulfur values. Davis magnetic tube tests on flotation tailings lowered the residual sulfur to 0. 1 % or less by recovering mainly pyrrhotite. PGM recoveries paralleled the recoveries of sulfur, although Pd recoveries remained somewhat lower, implying that a part of Pd might be associated with pyrrhotite. Pd, not recovered in flotation, appeared to be recovered by magnetic separation of flotation tailings.
Correlating Particle Size, Geochemical, and Gamma-Ray Log Data Relationships at the Ochs Brick and Tile Company Springfield Clay Mine, Springfield, Minnesota
(University of Minnesota Duluth, 1998) Zanko, Lawrence M; Setterholm, Dale R
Borehole geophysical techniques can be very useful for characterizing the physical and chemical characteristics of sedimentary deposits. A comparison of down-hole gamma-ray response to particle size and geochemistry shows that the down-hole gamma-ray logging technique effectively distinguished between intervals of varying composition at the Ochs Brick and Tile Company (OBT) Springfield clay mine in Brown County, Minnesota. Particle size (grain size) has a first order effect on the gamma activity; it is likely that mineralogy also is a significant contributor to variations of radioactivity. The naturally occurring radionuclides K, U, and Th in selected drill core samples show that K dominates the total gamma measurements obtained from borehole logging equipment. Consistency of the U and Th activities indicate no significant post-depositional migration of isotopes with the decay series for each nuclide and reflect the average crustal abundance for each. While the collection and laboratory testing of drill hole samples should be attempted whenever possible (especially during property exploration and development), the down-hole gamma-ray probe can provide additional valuable stratigraphic information. Therefore, gamma-ray logs would be especially beneficial where: 1) extensive drill hole sampling is impractical; or 2) the drilling method makes determining stratigraphic position and unit composition difficult or impossible, e.g., auger drilling. However, if gamma-ray logging is to be used extensively during exploration or property development, down-hole sampling should still be done to establish basic relationships between the "typical" gamma-ray profile and the type of material present at the property in question.

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