George J. Simandl

Bio: George J. Simandl is an academic researcher from University of Victoria. The author has contributed to research in topics: Geology & Geochemistry. The author has an hindex of 11, co-authored 22 publications receiving 438 citations.

Carbonatites: related ore deposits, resources, footprint, and exploration methods

Abstract: Most carbonatites were emplaced in continental extensional settings and range in age from Archean to recent. They commonly coexist with alkaline silicate igneous rocks, forming alkaline-carbonatite...

Geology, market and supply chain of niobium and tantalum—a review

Abstract: Tantalum (Ta) and niobium (Nb) are essential metals in modern society. Their use in corrosion prevention, micro-electronics, specialty alloys and high-strength low-alloy (HSLA) steel earns them a strategic designation in most industrialised countries. The Ta market is unstable due in part to historic influx of ‘conflict’ columbite-tantalite concentrate, or “Coltan,” that caused Ta mines in Australia and Canada to be placed on care and maintenance. More recently, the growing appetite of modern society for consumer goods made of ‘conflict-free’ minerals or metals has put pressure on suppliers. Pegmatites, rare-element-enriched granites, related placer deposits and weathered crusts overlying carbonatite and peralkaline complexes account for the majority of Ta production. Several carbonatite-related deposits (e.g. Upper Fir and Crevier, Canada) are being considered for potential co-production of Ta and Nb. Pyrochlore (Nb–Ta), columbite-tantalite (Nb–Ta), wodginite (Ta, Nb and Sn) and microlite (Ta and Nb) are the main ore minerals. Approximately 40 % of Ta used in 2012 came from Ta mines, 30 % from recycling, 20 % from tin slag refining and 10 % from secondary mine concentrates. Due to rapid industrialisation and increased use of Nb in steel making in countries such as China and India, demand for Nb is rising. Weathered crusts overlying carbonatite complexes in Brazil and one hard rock carbonatite deposit in Canada account for about 92 and 7 % of Nb world mine production, respectively. Since the bulk of the production is geographically and politically restricted to a single country, security of supply is considered at risk. Other prospective resources of Nb, beside carbonatites and associated weathered crusts, are peralkaline complexes (e.g. Nechalacho; where Nb is considered as a potential co-product of REE and zirconium). Economically, significant deposits of Ta and Nb contain pyrochlore, columbite-tantalite, fersmite, loparite and struverite. Assuming continued elasticity of Ta and Nb prices and that the law of the supply and demand applies, new sources of these metals can be developed. In the long term, there is no need to worry about Ta and Nb availability. Temporary disruptions in Ta and Nb supply are possible and could be difficult to cope with, so new sources of supply may be developed to diversify geographic sources of supply for strategic reasons.

Geology and market-dependent significance of rare earth element resources

Abstract: China started to produce rare earth elements (REEs) in the 1980s, and since the mid-1990s, it has become the dominant producer. Rare earth element export quotas first introduced by the Chinese government in the early 2000s were severely reduced in 2010 and 2011. This led to strong government-created disparity between prices within China and the rest of the world. Industrialized countries identified several REEs as strategic metals. Because of rapid price increases of REE outside of China, we have witnessed a world-scale REE exploration rush. The REE resources are concentrated in carbonatite-related deposits, peralkaline igneous rocks, pegmatites, monazite ± apatite veins, ion adsorption clays, placers, and some deep ocean sediments. REE could also be derived as a by-product of phosphate fertilizer production, U processing, mining of Ti-Zr-bearing placers, and exploitation of Olympic Dam subtype iron oxide copper gold (IOCG) deposits. Currently, REEs are produced mostly from carbonatite-related deposits, but ion adsorption clay deposits are an important source of heavy REE (HREE). Small quantities of REE are derived from placer deposits and one peralkaline intrusion-related deposit. The ideal REE development targets would be located in a politically stable jurisdiction with a pro-mining disposition such as Canada and Australia. REE grade, HREE/light REE (LREE) ratio of the mineralization, tonnage, mineralogy, and permissive metallurgy are some of the key technical factors that could be used to screen potential development projects. As REEs are considered strategic metals from economic, national security, and environmental points of view, technical and economic parameters alone are unlikely to be used in REE project development decision-making. Recycling of REE is in its infancy and unless legislated, in the short term, it is not expected to contribute significantly to the supply of REE.

The Nature and Origin of the REE Mineralization in the Wicheeda Carbonatite, British Columbia, Canada

Abstract: The Wicheeda carbonatite is a deformed plug or sill that hosts relatively high grade light rare earth elements (LREE) mineralization in the British Columbia alkaline province. It was emplaced within metasedimentary rocks belonging to the Kechika Group, which have been altered to potassic fenite near the intrusion and sodic fenite at greater distances from it. The intrusion comprises a ferroan dolomite carbonatite core, which passes gradationally outward into calcite carbonatite. The potentially economic REE mineralization is hosted by the dolomite carbonatite. Three types of dolomite have been recognized. Dolomite 1 constitutes the bulk of the dolomite carbonatite, dolomite 2 replaced dolomite 1 near veins and vugs, and dolomite 3 occurs in veins and vugs together with the REE mineralization. Carbon and oxygen isotope ratios indicate that the calcite carbonatite crystallized from a magma of mantle origin, that dolomite 1 is of primary igneous origin, that dolomite 2 has a largely igneous signature with a small hydrothermal component, and that dolomite 3 is of hydrothermal origin. The REE minerals comprise REE fluorocarbonates, ancylite-(Ce), and monazite-(Ce). In addition to dolomite 3, they occur with barite, molybdenite, pyrite, and thorite. Minor concentrations of niobium are present as magmatic pyrochlore in the calcite carbonatite. A model is proposed in which crystallization of calcite carbonatite preceded that of dolomite carbonatite. During crystallization of the latter, an aqueous-carbonic fluid was exsolved, which mobilized the REE as chloride complexes into vugs and fractures in the dolomite carbonatite, where they precipitated mainly in response to the increase in pH that accompanied fluid-rock interaction and, in the case of the REE fluorocarbonates, decreasing temperature. These fluids altered the host metasedimentary rock to potassic fenite adjacent to the carbonatite and, distal to it, they mixed with formational waters to produce sodic fenite.

Geological, Ocean, and Mineral CO2 Sequestration Options: A Technical Review

Abstract: Of the six greenhouse gases (GHG) covered by the Kyoto protocol, carbon dioxide (CO 2 ) is the greatest contributor to Canada's total GHG emissions. Fossil fuel combustion is the main source of anthropogenic CO 2 , and it currently supplies over 85% of the global energy demand. Worldwide, an effort for reduction of CO 2 emissions aims at increased efficiency of fossil energy usage, development of energy sources with lower carbon content and increased reliability on alternative energy sources such as wind, solar, geothermal and nuclear. However, to meet the objectives of the Kyoto agreement, CO 2 sequestration methods may be needed. In this review, the methods that we will cover are storage in oil and gas reservoirs, in deep coal seams, in deep saline aquifers, in deep ocean, in salt caverns, and mineral carbonation. Each of these methods has its weaknesses and strengths. RESUME Des six types de gaz a effet de serre (GES) dont il est question dans le traite de Kyoto, le gaz carbonique (CO 2 ) est celui qui contribue le plus au emissions totales de GES au Canada. La combustion de carburants fossiles qui repond presentement a 85 % des besoins d'energie de notre monde, constitue la principal source de CO 2 anthropogenique. L'effort mondial de reduction des emissions de CO 2 vise a augmenter l'efficacite de l'utilisation des energies fossiles, a developper des sources d'energie contenant moins de carbone et a augmenter l'apport d'autres sources d'energie comme le vent, le soleil, l'energie geothermique et l'energie nucleaire. Cependant, pour atteindre les objectifs du traite de Kyoto, on devra peut-etre recourir a des methodes de sequestration du CO 2 . Dans la presente etude retrospective, les methodes considerees sont les suivantes : le stockage dans des reservoirs de petroleet de gaz, dans des couches de charbon en profondeur, dans des aquiferes salins profonds, dans le fond des oceans, dans des cavernes de gisements de sel, ainsi que par carbonatation de mineraux. Chacune de ces methodes presentent des avantages et des inconvenients.

Toward Solar Fuels: Photocatalytic Conversion of Carbon Dioxide to Hydrocarbons

Abstract: The past several decades have seen a significant rise in atmospheric carbon dioxide levels resulting from the combustion of hydrocarbon fuels. A solar energy based technology to recycle carbon dioxide into readily transportable hydrocarbon fuel (i.e., a solar fuel) would help reduce atmospheric CO2 levels and partly fulfill energy demands within the present hydrocarbon based fuel infrastructure. We review the present status of carbon dioxide conversion techniques, with particular attention to a recently developed photocatalytic process to convert carbon dioxide and water vapor into hydrocarbon fuels using sunlight.