Reports of Investigations

Persistent link for this collectionhttps://hdl.handle.net/11299/187080

Please note: This collection contains all Reports of Investigations produced by NRRI. We are in the process of sorting these reports by subject; for Reports of Investigations sorted by specific subject, please see the subject-specific collections (which contain Reports of Investigations, Technical Reports, and Technical Summary Reports):

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Opportunities Offered by Emerging Hydrometallurgical Technologies
(University of Minnesota Duluth, 2022-08) Rao, Shashi; Mlinar, Matthew A; Hudak, George J; Kangas, Kevin W; Peterson, Dean M
Minnesota has abundant mineral resources, including deposits of iron, iron manganese, copper-nickel- cobalt-platinum group elements, titanium-vanadium, copper-zinc, gold with and without silver, sand, and aggregate. Commercial and industrial byproducts such as mine tailings, industrial residues, and waste electrical and electronic equipment also contain valuable mineral resources. To address significant environmental impact concerns associated with mining, collection and processing of these materials, new processing technology approaches with reduced water and energy consumption and minimal environmental footprints are needed to support production of value-added products. Emerging hydrometallurgical processing technologies offer promising opportunities. Hydrometallurgy techniques have a range of applications from extraction of high-value products from mineral and recycled materials to water remediation to generating secondary products for carbon sequestration. To evaluate the technical, economic, and environmental resiliency of emerging hydrometallurgical innovations, the Minnesota Legislative-Citizen’s Commission on Minnesota Resources (LCCMR) provided funding to the Natural Resources Research Institute (NRRI) to evaluate how to best support the development of emerging hydrometallurgical technologies in the state. To support this effort, NRRI evaluated: 1) A summary of perceived current and future hydrometallurgical needs of stakeholders based on a “voice of customer” (VOC) survey. 2) A discussion of how to apply hydrometallurgical capabilities to Minnesota-specific mineral and waste resources to maximize long-term economic, environmental, and social benefits and resilience. 3) A vision developed to advance Minnesota’s research capabilities in mineral characterization, mineral processing, extraction, and refining via hydrometallurgy that will lead to more efficient and effective utilization of Minnesota minerals and waste resources in the future. This research digs deeper into emerging applications of hydrometallurgical techniques in the production of value-added materials from a range of primary and secondary resources. The report also explores how application of these techniques to regional resources could potentially foster a more diversified minerals economy in Minnesota, develop treatment technologies to protect water resources, utilize regional resources for carbon mineralization, and supply materials required to build clean energy technologies.
Examination of Non-Lithium Battery Storage Concepts
(University of Minnesota Duluth, 2021-06) Fosnacht, Donald R; Peterson, Dean M; Myers, Evan
This study was undertaken to inform State of Minnesota Energy Policy and is funded by the Legislative-Citizens Commission on Minnesota Resources (LCCMR). It is focused on identifying alternative energy storage opportunities for the state. Various battery storage techniques for renewable energy are under active development by various parties, and many of these technologies are geared for energy storage for 2- to 4-hour duration. Other non-battery technologies are also under active development. These do not involve electrochemical storage concepts. This report summarizes non-lithium ion battery approaches that take advantage of physical principles involving gravity, compressing air and/or carbon dioxide, using hot carbon dioxide or molten salts or flywheel systems to capture energy that can be converted into electricity when renewable energy sources are unable to provide what is required. The use of these concepts can lead to long-duration storage that can facilitate better capture of available renewable energy and potentially eliminate the need for natural gas-based peaking plants to provide a more stable electrical supply when intermittent (e.g., solar or wind) resources cannot supply the necessary electricity. Additionally, the future impact of hydrogen as a means for long-duration energy storage is considered, especially using ammonia as a storage media. It is also apparent that redox flow batteries may also be useful in supporting storage needs beyond 2- to 4-hour duration. The techniques noted do not require nickel, cobalt, or lithium resources, have improved environmental characteristics, and in most cases reduced fire hazards compared to lithium ion-based battery systems. Finally, geographic information system (GIS) analysis is applied to better understand where the technologies can be potentially adopted at specific locations in the state of Minnesota. Some technologies need very specific geologic features for ready site selection; others can be placed if suitable near-grid locations are available.
Measuring what matters: Assessing the full suite of benefits of OHF investments
(2021-01-08) Noe, Ryan; Locke, Christina; Host, George; Gorzo, Jessica; Johnson, Lucinda; Lonsdorf, Eric; Grinde, Alexis; Joyce, Michael; Bednar, Josh; Dumke, Josh; Keeler, Bonnie
Little Tamarack River and Wright Bog Stream Flow – October 2019
(University of Minnesota Duluth, 2020-03) Johnson, Kurt W; Henneck, Jerald
Minnesota Taconite Workers Health Study: Environmental Study of Airborne Particulate Matter in Mesabi Iron Range Communities and Taconite Processing Plants - Lake Sediment Study
(University of Minnesota Duluth, 2019-12) Zanko, Lawrence M; Reavie, Euan D; Post, Sara P
Atmospheric deposition of airborne particulate matter such as fugitive dust contributes to sediment that accumulates at the bottom of a lake. Because of this phenomenon, lake sediment can provide an historic mineralogical and chemical record of what may have been in the air at the time of its atmospheric deposition. This point is important, because the NRRI’s role in the Minnesota Taconite Workers Health Study (MTWHS) was to not only help answer the question “What is in the air?” by conducting present-day in-plant and community air sampling, but – and even more challengingly – to potentially answer the question “What was in the air, when?” by collecting and analyzing historic samples. Lake sediment was the only historic sampling medium available that could allow the investigators to make an attempt to assess what might have been present in the air in the past on Minnesota’s Mesabi Iron Range (MIR). The NRRI therefore core-sampled, age-dated, and characterized intervals of sediment from two MIR lakes – Silver Lake in Virginia, on the central MIR, and “North-of-Snort” Lake on the eastern end of the MIR, near Babbitt (Fig. i). The objective was to determine if fugitive mineral dust generated by past iron ore/taconite mining activity could be discerned in mineral particulate matter (PM) deposited and preserved in the sediment of both lakes.
Minnesota Taconite Workers Health Study: Environmental Study of Airborne Particulate Matter in Mesabi Iron Range Communities and Taconite Processing Plants - Elemental Chemistry of Particulate Matter
(University of Minnesota Duluth, 2019-12) Monson Geerts, Stephen D; Hudak, George J; Marple, Virgil; Lundgren, Dale; Gordee, Sarah M; Olson, Bernard; Zanko, Lawrence M
The Minnesota Taconite Workers Health Study (MTWHS) was initiated in 2008 and included a multicomponent study to further understand taconite worker health issues on the Mesabi Iron Range (MIR) in northeastern Minnesota. Approximately $4.9 million funding was provided by the Minnesota Legislature to conduct five separate studies related to this initiative, including: ▪ An Occupational Exposure Assessment, conducted by the University of Minnesota School of Public Health (SPH); ▪ A Mortality (Cause of Death) study, conducted by the University of Minnesota SPH; ▪ Incidence studies, conducted by the University of Minnesota SPH; ▪ A Respiratory Survey of Taconite Workers and Spouses, conducted by the University of Minnesota SPH; and ▪ An Environmental Study of Airborne Particulate Matter, conducted by the Natural Resources Research Institute (NRRI) at the University of Minnesota Duluth (UMD). NRRI’s “Environmental Study of Airborne Particulate Matter” comprises a multi-faceted characterization of size-fractionated airborne particulate matter (PM) from MIR community “rooftop” locations, background sites, and all taconite processing facilities active between 2008 and 2014. Characterization includes gravimetric determinations, chemical characterization, mineralogical characterization, and morphological characterization. This report specifically discusses the elemental chemistry of particulate matter (PM) collected from the rooftops of five communities located within the Mesabi Iron Range (MIR), three reference or background locations, and the six taconite processing plants while they were active (operating) and inactive (temporarily, but completely, shut down). The samples were collected between 2008 and 2011.
Minnesota Taconite Workers Health Study: Environmental Study of Airborne Particulate Matter in Mesabi Iron Range Communities and Taconite Processing Plants - A Characterization of the Mineral Component of Particulate Matter
(University of Minnesota Duluth, 2019-12) Monson Geerts, Stephen D; Hudak, George J; Marple, Virgil; Lundgren, Dale; Zanko, Lawrence M; Olson, Bernard; Bandli, Bryan
The Minnesota Taconite Workers Health Study (MTWHS) was initiated in 2008 and included a multicomponent study to further understand taconite worker health issues on the Mesabi Iron Range (MIR) in northeastern Minnesota. Approximately $4.9 million funding was provided by the Minnesota Legislature to conduct five separate studies related to this initiative, including:  An Occupational Exposure Assessment, conducted by the University of Minnesota School of Public Health (SPH);  A Mortality (Cause of Death) study, conducted by the University of Minnesota SPH;  Incidence studies, conducted by the University of Minnesota SPH;  A Respiratory Survey of Taconite Workers and Spouses, conducted by the University of Minnesota SPH; and  An Environmental Study of Airborne Particulate Matter, conducted by the Natural Resources Research Institute (NRRI) at the University of Minnesota Duluth (UMD). Results of the four studies conducted by the University of Minnesota SPH can be found on the Taconite Workers Health Study website (http://taconiteworkers.umn.edu/news/documents/Taconite_FinalReport_120114.pdf). NRRI’s “Environmental Study of Airborne Particulate Matter” comprises a multi-faceted characterization of size-fractionated airborne particulate matter (PM) from MIR community “rooftop” locations, background sites, and all taconite processing facilities active between 2008 and 2014. Characterization includes gravimetric determinations, chemical characterization, mineralogical characterization, and morphological characterization. This report specifically discusses the mineralogy and morphology of EMPs collected from the rooftops of five communities located within the MIR, three reference or background locations, and the six taconite processing plants. The samples were collected between 2008 and 2011.
Minnesota Taconite Workers Health Study: Environmental Study of Airborne Particulate Matter in Mesabi Iron Range Communities and Taconite Processing Plants - Mesabi Iron Range Community Particulate Matter Collection and Gravimetric Analysis
(University of Minnesota Duluth, 2019-12) Monson Geerts, Stephen D; Hudak, George J; Marple, Virgil; Lundgren, Dale; Zanko, Lawrence M; Olson, Bernard
The Minnesota Taconite Workers Health Study (MTWHS) was initiated in 2008 and included a multicomponent study to further understand taconite worker health issues on the Mesabi Iron Range (MIR) in northeastern Minnesota. Approximately $4.9 million funding was provided by the Minnesota Legislature to conduct five separate studies related to this initiative, including:  An Occupational Exposure Assessment, conducted by the University of Minnesota School of Public Health (SPH);  A Mortality (Cause of Death) study, conducted by the University of Minnesota SPH;  Incidence studies, conducted by the University of Minnesota SPH;  A Respiratory Survey of Taconite Workers and Spouses, conducted by the University of Minnesota SPH; and  An Environmental Study of Airborne Particulate Matter, conducted by the Natural Resources Research Institute (NRRI) at the University of Minnesota Duluth (UMD). NRRI’s “Environmental Study of Airborne Particulate Matter” comprises a multi-faceted characterization of size-fractionated airborne particulate matter (PM) from MIR community “rooftop” locations, background sites, and all taconite processing facilities active between 2008 and 2014. Characterization includes gravimetric determinations, chemical characterization, mineralogical characterization, and morphological characterization. This report specifically discusses the methods and gravimetric results of multiple aerosol PM sample collections from five communities located within the MIR, as well as three background locations. The samples were collected between 2008 and 2011.
Minnesota Taconite Workers Health Study: Environmental Study of Airborne Particulate Matter in Mesabi Iron Range Communities and Taconite Processing Plants - Taconite Processing Facilities Particulate Matter Collection and Gravimetric Analysis
(University of Minnesota Duluth, 2019-12) Monson Geerts, Stephen D; Hudak, George J; Marple, Virgil; Lundgren, Dale; Zanko, Lawrence M; Olson, Bernard
The Minnesota Taconite Workers Health Study (MTWHS) was initiated in 2008 and included a multicomponent study to further understand taconite worker health issues on the Mesabi Iron Range (MIR) in northeastern Minnesota. Approximately $4.9 million funding was provided by the Minnesota Legislature to conduct five separate studies related to this initiative, including:  An Occupational Exposure Assessment, conducted by the University of Minnesota School of Public Health (SPH);  A Mortality (Cause of Death) study, conducted by the University of Minnesota SPH;  Incidence studies, conducted by the University of Minnesota SPH;  A Respiratory Survey of Taconite Workers and Spouses, conducted by the University of Minnesota SPH; and  An Environmental Study of Airborne Particulate Matter, conducted by the Natural Resources Research Institute (NRRI) at the University of Minnesota Duluth (UMD). NRRI’s “Environmental Study of Airborne Particulate Matter” comprises a multi-faceted characterization of size-fractionated airborne particulate matter (PM) from MIR community “rooftop” locations, background sites, and all taconite processing facilities active between 2008 and 2014. Characterization includes gravimetric determinations, chemical characterization, mineralogical characterization, and morphological characterization. This report specifically discusses the methods and gravimetric results of multiple aerosol PM sample collections from active (operating) and inactive (temporarily, but completely, shut down) taconite plants on the MIR. Taconite plant samples were collected in 2009 and 2010.
Minnesota Taconite Workers Health Study: Environmental Study of Airborne Particulate Matter in Mesabi Iron Range Communities and Taconite Processing Plants - Development of Standard Operating Procedures for Particulate Collection and Gravimetric Analysis
(University of Minnesota Duluth, 2019-12) Monson Geerts, Stephen D; Hudak, George J; Marple, Virgil; Lundgren, Dale; Olson, Bernard; Zanko, Lawrence M; Bandli, Bryan; Brecke, Devon M
The Minnesota Taconite Workers Health Study (MTWHS) was initiated in 2008 and included a multicomponent study to further understand taconite worker health issues on the Mesabi Iron Range (MIR) in northeastern Minnesota. Approximately $4.9 million funding was provided by the Minnesota Legislature to conduct five separate studies related to this initiative, including:  An Occupational Exposure Assessment, conducted by the University of Minnesota School of Public Health (SPH);  A Mortality (Cause of Death) study, conducted by the University of Minnesota SPH;  Incidence studies, conducted by the University of Minnesota SPH;  A Respiratory Survey of Taconite Workers and Spouses, conducted by the University of Minnesota SPH; and  An Environmental Study of Airborne Particulate Matter, conducted by the Natural Resources Research Institute (NRRI) at the University of Minnesota Duluth (UMD). NRRI’s “Environmental Study of Airborne Particulate Matter” comprises a multi-faceted characterization of size-fractionated airborne particulate matter (PM) from MIR community “rooftop” locations, background sites, and all taconite processing facilities active between 2008 and 2014. Characterization includes gravimetric determinations, chemical characterization, mineralogical characterization, and morphological characterization. This report discusses the standard operating procedures for particle collection and gravimetric analysis. The methodology and practices that have been developed and performed have been completed in conjunction with NRRI’s Science Advisory Board and in collaboration with aerosol scientists at the University of Minnesota Department of Mechanical Engineering and University of Florida-Gainesville. As well, this report outlines the development of the sampling methodology and the history of in-house experiments conducted throughout the project to strengthen the sampling design that ultimately resulted in the development of the standard operating procedures adopted by, and practiced in, this portion of the study. Definitions for specific terms used in this document are consistent with terminology described in Appendix G.
Mapping Industrial Clay Potential in the Minnesota River Valley
(University of Minnesota Duluth, 1998-12) Zanko, Lawrence M; Oreskovich, Julie A; Heine, John J; Grant, James A; Hauck, Steven A; Setterholm, Dale R
Oxide, Sulphide and Platinum Mineralogy of the South Kawishiwi and Partridge River Intrusions of the Duluth Layered Intrusion Complex Minnesota, U.S.A.
(University of Minnesota Duluth, 1998) Komppa, Ulla; Hicks, Malcolm
The Duluth Complex in north-east Minnesota, U.S.A., is one of the largest basic layered intrusion complexes in the world, occupying an area of about 4700 km2 • It is composed of several separate intrusions which discharged via the Midcontinent Rift System about 1100 ± 15 Ma ago. Characteristic of the complex is the occurrence of mineralizations containing Cr-Fe-Ti-V oxides, CuNi sulphides and platinum group elements in the troctolitic South Kawishiwi and Partridge River Intrusions on its western and northern edges. The purpose of this work is to study and compare these two adjacent intrusions in terms of their platinum mineralogy and to provide the basic data necessary for determining the origins of their mineralizations. As the platinum mineralizations are closely connected with oxide and sulphide mineralizations, the latter are also examined in detail. The work is based to a great extent on the available literature and on a set of 221 core samples taken from the two intrusions. A total of 119 whole rock x-ray fluorescence analyses, 253 WDS x-ray microanalyses, 68 EDS analyses and 499 scanning electron microscope analyses ( also employing the EDS method) were performed on these cores for the determination of oxides, sulphides and platinum group minerals. The mineralizations of the Duluth Layered Intrusion Complex resemble other corresponding ones in Cu and Ni-bearing basic igneous rocks in their ore mineralogy and in the rock types present. The mineralizations exhibit properties suggestive of a role for both magmatic and hydrothermal processes in the distribution of platinum group elements. The results obtained here are consistent with earlier findings.
Preliminary Evaluation of Drilling Activities in the Koochinching-Beltrami-Roseau-Lake of the Woods Counties in Northern Minnesota
(University of Minnesota Duluth, 2012-08) Severson, Mark J; Heine, John J
The main objective of this project is to make a first pass evaluation of the volcanic-hosted massive sulfide (VMS) potential, through a literature search of exploration files, for a portion of the Wabigoon greenstone belt in northern Minnesota. The area chosen for this investigation is situated in portions of Koochiching, Beltrami, Roseau, and Lake of the Woods counties (abbreviated as KBRLW area). Over 230 holes were drilled in the KBRLW area during 1952-1997 by numerous exploration companies, the Minnesota Geological Survey (for geologic mapping purposes), and the Minnesota Department of Natural Resources (for overburden sampling and geologic mapping purposes). A review of the historical drill logs indicates that semi-massive to massive sulfide mineralization, mostly pyrite and pyrrhotite, was intersected in 52 of the 230 holes. A review of the geochemistry indicates that there are three belts in the KBRLW area wherein groups of drill holes encountered mildly anomalous zinc values (>0.45% Zinc) associated with sulfide-rich intervals. These belts are informally named the “Baudette Belt,” “Oaks Belt,” and “Birchdale Belt.” The most impressive zinc assays, up to 4.9% Zn in drill hole B24-2, are associated with the “Oaks Belt.” A nearby hole, BD-N-1, intersected over 302 feet of reported massive to semi-massive sulfide that averaged 0.2% Zn with a maximum of 0.73% Zn – this hole was terminated in semi-massive sulfide. There are 17 holes in the “Baudette Belt” that intersected massive to semi-massive sulfide, 5 of which contained zones with >0.45% zinc but only a maximum of 0.7% zinc. Only one hole in the “Birchdale Belt” contained anomalous zinc (4.06% Zn); however, the occurrence was an isolated anomaly that was never repeated in nearby drill holes. In regards to gold assay data, the “Baudette Belt” contains the vast majority of holes with significant gold shows (>450 ppb Au threshold). One hole from the “Baudette Belt” (hole FT-14) is the most unique of this group in that it contains an 11-foot-thick interval that averages 1,185 ppb Au with a maximum of 2,745 ppb Au. Overall, the available data suggests that the “Baudette Belt” appears to have the best potential of hosting an economic VMS deposit. Furthermore, the “Baudette Belt” also appears to exhibit the best gold potential as borne out by the presence of several holes with anomalous gold (>450 ppb Au). Detailed re-logging of the drill holes in this belt should take place in order to more fully refine the geology/lithostratigraphy and alteration footprints.
Electron Microprobe Analysis of Alteration Mineralogy at the Archean Five Mile Lake Volcanic Associated Massive Sulfide Mineral Prospect in the Vermilion District of Northeastern Minnesota
(University of Minnesota Duluth, 2003-05) Hocker, Stephanie M; Hudak, George J; Heine, John J
Alteration mineral assemblage mapping at the Five Mile Lake Prospect in the Vermilion District of northeastern Minnesota has identified two distinct types of alteration zones within 2.7 billion year-old volcanic and volcaniclastic rocks associated with volcanic-hosted massive sulfide (VHMS) mineralization (Hudak et al., in press; Odette et al., 2001a, 2001b; Peterson, 2001). Regional semi-conformable alteration zones are composed of various proportions of quartz + epidote ± amphibole ± chlorite ± plagioclase feldspar. These regional, semiconformable alteration zones are locally crosscut by several relatively narrow, northeasttrending disconformable alteration zones composed of fine-grained chlorite and/or sericite that are closely associated with synvolcanic fault zones. Electron microprobe analyses of the various alteration mineral phases (epidote group minerals, chlorite, amphibole, white mica, and feldspar) have been conducted in an effort to better understand the hydrothermal processes associated with the development of the semiconformable and disconformable alteration zones at the Five Mile Lake Prospect. These analyses indicate that: a) epidote group minerals range in composition from zoisite/clinozoisite to pistacite; b) chlorite is dominantly ripidolite; c) amphibole is primarily actinolite and ferroactinolite, with magnesio-hornblende and ferro-hornblende also present; d) sericite is finegrained muscovite; and e) feldspar is albite. This mineral chemistry suggests the presence of a complex, long-lived hydrothermal system that evolved from seafloor-proximal (hundreds of meters) to deeper subseafloor environments (~1-3 km) as the volcanic rocks were buried by rapid, dominantly effusive mafic to intermediate volcanism and associated sedimentation. Alteration mineral chemistry at the Five Mile Lake Prospect is remarkably similar to that from the Noranda VHMS mining camp of Canada as well as other VHMS orebodies. This mineral chemistry, combined with favorable volcanology and numerous untested geophysical targets, suggest that the Five Mile Lake Prospect, as well as the uppermost several hundred meters of the Lower Member of the Ely Greenstone, have excellent exploration potential for VHMS mineral deposits.
Historical Use of Taconite Byproducts as Construction Aggregate Materials in Minnesota: A Progress Report
(University of Minnesota Duluth, 2006-10) Oreskovich, Julie A; Patelke, Marsha Meinders
Coarse taconite tailings and crushed taconite rock (Mesabi Hard Rock™) have been a staple of the road construction industry on Minnesota’s Mesabi Iron Range for over four decades. Comparable to trap rock in quality, taconite aggregates have proven to be strong and durable when used as subgrade and base material and in bituminous pavements. The superior hardness and durability of these materials make them a viable candidate for exporting to the Twin Cities metro and out-state areas and to surrounding states as stand alone aggregate or for blending with local aggregates to produce more competent pavements. Documenting how and where taconite byproducts have been used in Minnesota, along with related test and longevity data, will provide the potential end user a basis for selecting these materials over another aggregate source.
Imagining Scientific Realities Deep Underground: Utilizing Knowledge and 3-D Geological Modeling, Fundamental Tenets of The University of Minnesota’s Proposed Institute for Underground Science and Soudan Dusel
(University of Minnesota Duluth, 2007-03) Peterson, Dean M
The ultimate goal of scientific research is to enhance knowledge, thus allowing one (or all) to imagine reality. The most renowned physicists, e.g., Nicholas Copernicus, Galileo Galilei, Isaac Newton, Max Planck, Albert Einstein, and Niels Bohr, and geologists, e.g., Nicholas Steno, William Smith, Charles Lyell, Louis Agassiz, Alfred Wegener, Harry Hess, and J. Tuzo Wilson, all used their individual imaginations to open the door to new scientific realities that we as a society now realize. Quite possibly the greatest scientific reality ever imagined is Charles Darwin’s theory of Natural Selection (“On the Origin of Species,” published in 1859). The National Science Foundation’s (NSF) goal of scientific research at a U.S. Deep Underground Science and Engineering Laboratory (DUSEL) is to enhance our collective knowledge of physics, geology, biology, and engineering through dedicated research in a deep underground setting. This short report highlights some of the geological features and their relationships to future science opportunities associated with the University of Minnesota’s most recent (January 9, 2007) DUSEL proposal to the NSF (Marshak et al., 2007). In this proposal, the University plans to develop the Institute for Underground Science (IUS) at the University of Minnesota and expand the current Soudan Underground Laboratory down to a depth of 1500m, i.e., 4125 meters of water equivalent (MWE) immediately southeast of its current location. The IUS would be a widely-collaborative, multidisciplinary institute with a mission to facilitate a coherent theoretical and experimental program in underground science and technology. Previous University of Minnesota DUSEL proposals (Marshak et al., 2003, 2005) have outlined the opportunities for deep underground science at the Soudan Mine near Tower, Minnesota, though an interdisciplinary science vision was not yet developed in the 2003 proposal, and the location of a Soudan DUSEL in the 2005 proposal was approximately one mile east (and thus largely hosted within a different stratigraphic sequence of rocks) than the recently proposed site at Soudan.
Photomicrographs of the Minerals of the Central and Western Mesabi Range
(University of Minnesota Duluth, 2009-09) Niles, Harlan B
The paper consist of photomicrographs that show colors, forms, occurences, and associations of minerals of the central and western Mesabi Range. These minerals are minnesotaite, talc, stilpnomelane, greenalite, chlorites, quartz, carbonates (mostly siderite and ankerite), magnetite, hematite, and goethite.
SEM Image Comparison of Selected Crushed Mineral Standards Sample Preparation and Analysis
(University of Minnesota Duluth, 2010-09) Schreiber, Megan
The qualitative investigation observed, through scanning electron microscope (SEM) analysis, the morphological (size and shape) characteristics that specimen-grade mineral standards can exhibit on a microscopic scale following mechanical crushing. A hand-crushing technique (via mortar and pestle) was used to represent the macroscopic mineral crushing that occurs throughout the taconite mining industry. The results are intended to show how SEM analyses of these crushed standards can be used as a point of reference for comparison to crushed minerals found within the taconite ore and taconite mining by-products of Minnesota’s Mesabi Iron Range. For this SEM-based investigation, standards were chosen as analogs to three common minerals found on the western Mesabi Iron Range: quartz, magnetite, and stilpnomelane. A fourth mineral standard (actinolite) was chosen as an amphibole mineral that can occur in the contact-metamorphosed easternmost portion of the Mesabi Iron Range. The findings show that mechanical crushing can generate elongated mineral particles (EMP) from all four standards, including quartz. Simply put, an EMP is a particle having length-to-width ratio ≥3:1. Consequently, most – if not all – mineral processing and/or rock crushing operations nationwide have the potential to generate elongated mineral particles.
Finish Logging of Duluth Complex Drill Core
(University of Minnesota Duluth, 2007-10) Severson, Mark J; Hauck, Steven A
From 1988 through 2005, NRRI personnel had logged 955 drill holes from the basal zone of the Duluth Complex. The major result of all this effort was the establishment of igneous stratigraphic packages, which in turn, were used to improve our understanding of the mineralization controls on the Cu-Ni deposits and the distribution of Platinum Group Elements (PGE). However, at the beginning of the biennium there were still over 220 drill holes (226,000 feet of core) that remained to be re-logged from portions of the Partridge River and South Kawishiwi intrusions. The main objective of this proposal was to complete a logging campaign of these remaining holes and establish a complete stratigraphic section for these two intrusions of the Duluth Complex. To date, 224 holes have been relogged for this project totaling 198,979 feet of drill core. This total includes several holes that were recently drilled in the Maturi Extension/Nokomis deposit by Duluth Metals, and several recently found drill cores from the Dunka Pit deposit. All of the newly logged holes, see appendix, are located in eight deposits within the Partridge River and South Kawishiwi intrusions; including a few scattered holes in the Cloquet Lake and Tuscarora intrusions. The vast majority of relogged holes were from the Babbitt/Mesaba deposit due to the incredibly large number of drill holes drilled there in the first place. While this project made a significant dent in the total amount of holes logged at the Babbitt deposit, there are still about 20 holes that yet remain to be logged. In an addendum to this report, these drill holes at the Babbitt deposit will be logged, and an unknown number of additional drill holes at the Maturi Extension will be logged.
Taconite Tailings and Water Quality - A Survey of Existing Data
(University of Minnesota Duluth, 2010-09) Patelke, Marsha Meinders; Zanko, Lawrence M
For over 40 years, taconite tailings, a by-product of taconite iron ore processing, has been used in northeastern Minnesota road construction projects as aggregate. The dominant uses have been as fill materials and in bituminous pavements. Over 125 million tons of tailings are produced annually by Minnesota’s iron mining industry (Oreskovich et al., 2007). The Natural Resources Research Institute (NRRI), University of Minnesota Duluth, has been involved in a multiplephase project to evaluate the quality and use of this material. When used as aggregate for bituminous pavements, the taconite tailings grains are encapsulated in the asphalt mix that separates the tailings from contact with water. As fill, taconite tailings can be in contact with water, intermittently, seasonally, or continuously. Do taconite tailings affect water quality? In an effort to evaluate this question, a compilation and review of existing groundwater and surface water chemistry associated with tailings in contact with water has been completed. We evaluate water quality by comparing existing water sample chemical analyses data to published State of Minnesota ground and surface water standards. Data utilized for this study include: Minnesota Department of Natural Resources (DNR) reports from 1989 and 1999, Minnesota Pollution Control Agency (MPCA), Keetac Pollutant Discharge Elimination System (NPDES) permit water sampling data from several mines, and previous investigations completed by the Natural Resources Research Institute (NRRI). Based on our review, the data from water quality and taconite tailings revealed the following findings: 1. Most Minnesota water quality standards are met. The exceptions include arsenic, cobalt, iron, and manganese. Iron and manganese exceed secondary drinking water standards that are based on attributes of the water like taste, odor, and appearance, and not because of health risk issues. Arsenic and cobalt exceed the MPCA’s 2A chronic standard for surface waters of 2 ppb and 2.8 ppb, respectively. These elements do not exceed the drinking water standards or Class 7 surface water standards; 2. Mercury is typically an environmental concern. Based on the NPDES data reviewed, the following information was noted. Chemical analyses completed on surface water collected at three of the mines had the following reported numbers: maximum value 7.24 ng/L, minimum value 0.45 ng/L and a median value of 1 μg/L. Minimum and median reported mercury values meet the most stringent surface water standard, the Great Lakes Initiative, of 1.3 ng/L. Thirty-four water samples were analyzed for total mercury. A total of 678 NPDES water sample data were reviewed. DNR reports do not contain mercury data for water samples. Atmospheric mercury could add to the amount detected by chemical analyses in surface water samples; 3. Iron formation contains arsenic, cobalt, manganese, and iron; 4. Taconite tailings do contain arsenic, cobalt, manganese, and iron. Arsenic occurs at a minimum value of 8.8 mg/kg, maximum value of 39.4 mg/kg, and a median value of 17 mg/kg. Cobalt occurs at a minimum value of 4.4 mg/kg, maximum value of 15.4 mg/kg, and a median value of 7.7 mg/kg. Manganese and iron were not reported as trace metals but were included in whole rock analyses; 5. NRRI completed Toxicity Characterization Leaching procedure (TCLP) and Synthetic Precipitation Leaching Procedure (SPLP) chemical analyses on three samples of taconite tailings. Results indicated that arsenic results ranged from < 2 μg/L to 4.3 μg/L, slightly above the surface water quality chronic standard of 2.0 μg/L for 2A waters; 6. Further evaluation is recommended. Testing on taconite tailings samples, as well as other typical aggregates, should include physical and chemical parameters. Testing on samples of aggregate and water should be done to evaluate all sites by the same methods and current detection limits. Analytes should include: RCRA metals as well as cobalt. Additional testing should include grain size analyses and hydraulic conductivity; and 7. Mechanisms for the potential release of metals into surface water by tailings are dependent on water characteristics such as pH, Eh, time, hydrology, and reduction (redox) potential. Therefore, it is site specific. Additional testing of leachate from taconite tailings is suggested using SPLP test methods and could include pH dependent leaching and liquid to solid (L/S) ratio dependent leaching as described by Jambeck and Greenwood (2007) and Kosson (2002). Data derived from these test methods may produce results more applicable to use of taconite tailings as fill material in contact with wet environments.

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