Hudak, George JMonson Geerts, Stephen DChen, JonathanHalim, ASridhar, RamLakshmanan, V.I.2022-01-282022-01-282021-10https://hdl.handle.net/11299/226177Vanadium 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).enNatural Resources Research InstituteUniversity of Minnesota DuluthTechnical Report