Browsing by Subject "Nickel"
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Item Emplacement and Crystallization Histories of Cu-Ni-PGE Sulfide-mineralized Peridotites in the Eagle and Eagle East Intrusions(2018-06) Mulcahy, ConnorThe Eagle and Eagle East intrusions, located about 40 kilometers northwest of Marquette, MI, are two small, partially exposed, sub-vertical, funnel-shaped mafic/ultramafic intrusions emplaced in Paleoproterozoic black slates. Both intrusions host economic Ni-Cu-(PGE) sulfide deposits, the Eagle intrusion in its main body and the Eagle East intrusion in its feeder at depth. The Eagle deposit has been being mined by the Lundin Mining Corporation since 2014, which is now also expanding its operation to mine the Eagle East deposit. Transmitted light petrography, scanning electron microscopy, and electron microprobe analyses were performed on samples from six drill cores in the Eagle system, three from Eagle and three from Eagle East. Lundin additionally provided whole-rock geochemistry for five of these cores at ~1.5m intervals. The concentration of Ni in olivines in the Eagle and Eagle East intrusions were measured by electron microprobe. A bimodal distribution of Ni concentration in olivine - i.e., both enriched and unenriched populations being present - may have been evidence for multiple magma pulses in the Eagle system. However, olivine in both intrusions were determined to be universally Ni-enriched, which means that this line of inquiry was not useful for determining the number of magma pulses. The cumulate nature of samples were determined by whole-rock geochemistry, wherein incompatible trace elements including Zr, and La were used as proxies for the amount of intercumulus material present in a sample, as well as by visual estimation using transmitted-light petrography. Counter to the conclusions of Ding et el. (2010), variations in incompatible trace element ratios in various rock types in the Eagle system were satisfactorily explained by the cumulate nature and high sulfide content of the samples, with no need to invoke multiple parental magmas in the explanation. The intrusive breccia (or “IBRX”) lithology present in both the Eagle and Eagle East intrusions was studied with transmitted light petrography. It was determined to occur in at least two variations. Both variations have a feldspathic lherzolite matrix with subangular clasts, but in one type heavy sulfide mineralization (up to 30% by volume) occurs in the clasts and in the other type the clasts are nearly devoid of sulfides. In both cases the clasts have high pyroxene abundances and are devoid of olivine, but clasts with high sulfide content tend to have more plagioclase and are more heavily altered. In the Eagle East intrusion, sampled clasts were only of the low-sulfide variety. The IBRX clasts may be a slower-cooling version of the PRX lithology also present in the Eagle system. Alternatively, they may be part of an older intrusion that the Eagle system parental magma cannibalized at depth during emplacement. The main body of the Eagle East intrusion was studied by petrographic examination of a core that profiled its depth. While there was no significant change in cumulate rock type, the core did show modest cryptic variation with depth. Notably, a horizon of increased olivine abundance indicated the potential recharge of the intrusion with the same, homogeneous parental magma. The lithological similarity of the Eagle and Eagle East intrusions indicates that they likely formed from the same parental magma. The main petrographic differences between the two intrusions were the poikilitic nature of clinopyroxene and the lower abundance of plagioclase in the Eagle East intrusion. These differences may be explained by the larger size and thus presumed longer cooling time of the Eagle East intrusion.Item An Investigation of Ni and Cu Isotopic Fractionation in Basal Duluth Complex Cu-Ni-PGE Mineralization, Northeastern Minnesota(2016-05) Asp, KristoferCu-Ni-PGE magmatic sulfide-style mineralization occurs along the western margin of the Duluth Complex in northeastern Minnesota. Previous studies have demonstrated a notable fractionation of 60Ni and 58Ni in terrestrial materials, including both primary and secondary phases, with a total range of up to 2.1 ‰. Other work has indicated a fractionation of 65Cu and 63Cu, with pronounced differences between primary copper sulfides and secondary copper phases in a variety of deposit types. Prior to this study, no δ60/58Ni or δ65/63Cu values have been measured in Duluth Complex rocks. The primary goal of this study is to measure Ni and Cu isotope values in a variety of Duluth Complex samples, and develop a possible model for the δ60/58Ni isotopic system in this geologic terrane. Based on the findings of previous studies, samples were collected to determine the isotopic differences between sulfide-bearing and sulfide-barren material. Samples were collected from a variety of locations in the basal Duluth Complex, including glacial till beds and surface outcrops in the vicinity of the I, II, Serpentine, Mesaba, and NorthMet deposits. Additional drill core material was obtained from the III, Wetlegs, and Wyman Creek deposits. A detailed characterization of till, weathered surface, and primary drill core samples revealed three main sources of nickel in Duluth Complex material: silicate, sulfide, and secondary oxide. The 24 δ60/58Ni values have an overall range from -0.97 to 0.22 ‰, but are correspondingly distinct in each type of material: silicate (-0.03 ‰ average), sulfide (-0.36 ‰ average), secondary oxide (-0.50 ‰ average). Further geochemical and microprobe work, along with the isotopic values, indicate two main stages of Ni fractionation in basal Duluth Complex rocks: a high temperature stage during crystallization, and a low temperature stage during surficial weathering. High-T fractionation is defined by a preferential incorporation of 58Ni into sulfide, while silicates, especially olivine, are reflective of the Bulk Silicate Earth value. Low-T fractionation results in a preferential incorporation of 58Ni into secondary oxide, while 60Ni possibly enters solution and leaves the system. The 22 measured Duluth Complex δ65/63Cu values have an overall range from -1.28 ‰ to 0.36 ‰, with an overall average of -0.35 ‰. Further work is necessary to better define and interpret the involved fractionation processes in the Duluth Complex.Item Metallurgical Testing of Copper-Nickel Bearing Material from the Duluth Gabbro Progress Summary(University of Minnesota Duluth, 1998-06) Benner, Blair RThis report summarizes the progress of metallurgical testing of copper-nickel bearing material from the Duluth gabbro to date and outlines the plan for the ongoing test program being funded under the University of Minnesota Permanent Trust Fund (PUTF).Item NRRI Library to House Materials Related to Copper-Nickel Study(1989) Sandy, John H; Miller, PatriciaThis article describes a large collection of published materials, including journal articles, technical reports, theses, and other sources used by authors in writing and compiling a major report on the copper-nickel deposits and related environment in northern Minnesota. The collection was originally stored at the Environmental Conservation Library at the Minneapolis Public Library before being transferred to the Natural Resources Library at the Natural Resources Research Institute, University of Minnesota Duluth.Item NRRI Now (1989 Winter)(University of Minnesota Duluth, 1989) University of Minnesota Duluth. Natural Resources Research Institute; Sandy, John H; Miller, PatriciaIncludes an article on page 12 “NRRI Library to House Materials Related to Copper-Nickel Study” by John H. Sandy and Patricia Miller. This article describes a large collection of published materials, including journal articles, technical reports, theses, and other sources used by authors in writing and compiling a major report on the copper-nickel deposits and related environment in northern Minnesota. The collection was originally stored at the Environmental Conservation Library at the Minneapolis Public Library before being transferred to the Natural Resources Library at the Natural Resources Research Institute, University of Minnesota Duluth.Item Olefin Oligomerization on Nickel-Based Metal Organic Framework Catalysts(2023-07) Yeh, BenjaminOlefin oligomerization on nickel-based catalysts to produce linear alpha olefins, comonomers for polyethylene synthesis, requires the use of cocatalysts, involves transients during induction periods, and is plagued by catalyst deactivation. The need for cocatalysts and the observed induction period is ascribed to the formation of a nickel-alkyl intermediate which initiates propagation sequences described by the Cossee-Arlman mechanism as opposed to the metallacycle mechanism to form oligomers. This work investigates two nickel metal organic frameworks (MOFs), Ni/UiO-66 and Ni-MIL-127, that activate onstream devoid of cocatalysts and uniquely maintain stable oligomerization rates. The structures of both catalysts evolve under different chemical and thermal environments to generate catalytically relevant nickel species for olefin oligomerization, as evinced by transient and steady state rate measurements and spectroscopic methods. The active nickel species are enumerated with in-situ NO titrations to demonstrate that not all nickel species in the material are active for olefin oligomerization. Through analysis of steady state kinetics and product selectivities and comparison with experimental and computed activation energies with density functional theory on cluster models of Ni/UiO-66 and Ni-MIL-127, the Cossee-Arlman mechanism is postulated over the metallacycle mechanism for olefin oligomerization. These studies, which can be used to guide the synthesis of tunable MOFs for olefin oligomerization through a combination of experiment and theory, describe how the structures of MOFs change by undergoing active site generation and defect formation to enable distinct stability characteristics for olefin oligomerization catalysis.Item The Systematic Design of Nickel Complexes Toward Energy-Relevant Bond Activations(2022-07) Prat, JacobThe production of catalysts capable of the efficient and selective reactivity of CO2, H2, and CO toward useful products is required to lower global energy costs and allow for a sustainable carbon neutral future. To this end the design and synthesis of metal complexes capable of controlling the reactivity of these small molecules is highly desired. Bimetallic complexes allow for a greater chemical space allowing for high tailorability of metal catalyst properties presenting a new strategy for solving these issues. The tuning of a Z-type nickel-support bond toward small molecule reactivity unifies the chemistry described herein. In the introductory chapter the environmental and energy considerations motivating this work is made explicit. Inspired by enzymatic catalysis, a nickel-iron bimetallic complex for CO2 reduction to CO was studied in depth by NMR, Mössbauer, and electrochemical studies is detailed in Chapter 2. In Chapter 3 the role of a group 13 support on H2 binding and hydride transfer reactivity was investigated with the synthesis and characterization of a set of nickel-boron complexes. In Chapter 3 the combination of open ligand choice and metal support for the modulation of CO and CO2 binding was explored with iron and tin bimetallic nickel complexes.Item Tuning Nickel Electronics and Hydrogenation Reactivity with Rare Earth Metalloligands(2020-08) Ramirez, BiancaIndustrially, many chemical transformations require the use of expensive precious metal catalysts to proceed. A major chemical pursuit aims at replacing these expensive metals with inexpensive, Earth-abundant transition metals. Unfortunately, Earth-abundant transition metals are often poor catalysts for challenging multi-electron processes. One strategy to circumvent this problem makes use of σ-accepting (or Z-type) ligands to control the electronic characteristics and reactivity of a metal center. However, a heavy focus on main group metals within this field has yielded a lack of diversity in the metals employed as Z-type ligands. In this vein, this dissertation investigates the use of rare earth metals as Z-type ligands to promote homogenous transition metal catalysis. A series of nickel–rare earth (Sc, Y, lanthanides) heterobimetallic complexes were synthesized using new phosphinoamide ligands. The complexes were characterized using a suite of spectroscopic, electrochemical, and computational methods. The electronic effects of the rare earth supporting metals poised the Ni metal center for the hydrogenation of olefins to alkanes as well as alkynes to (E)-alkenes. Furthermore, it was found that altering the coordination sphere of the rare earth support significantly impacts the resulting properties and catalytic activity of the active Ni metal center. By quantitatively comparing structure, redox properties, and mechanistic intermediates, the effects of the supporting metal on the Ni electronics, catalytic activity, and kinetics of the Ni−M complexes were elucidated. Collectively, this work demonstrates that modulating a transition metal center via an appended rare earth support metal can favorably alter the properties of inexpensive metals, thus promoting a new reactivity paradigm in homogenous transition metal catalysis.