Results 1 - 10 of 20954
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[en] Helium isotopes have been measured in fluorite and sulphides in order to obtain conclusive means of assessing the involvement of mantle and crustally derived volatiles in F-Ba deposits from Asturias (N of Spain). Fluorite mineralizations are hosted in Mesozoic (Permotriassic) and Paleozoic age rocks. Mineralization is composed of fluorite, barite, calcite, dolomite, quartz and sulphides, and shares the characteristics of most Mississippi Valley Type (MVT) deposits associated with rifting events related to the opening of the Atlantic Ocean. The 3He/4He values of the Asturias ore fluids (≤ 0,1 Ra) indicate a crustal fluid source and exclude the involvement of a mantle helium component. These values are consistent with the acceptance of the existing basinal model for MVT genesis and sedimentary brines migration, with the lack of igneous activity in the area contemporary with the mineralization, and also consistent with similar helium isotope data recorded in other fluorite deposits in Europe. (Author) 24 refs.
[en] The great evolution of the technology development given in the last decade is undoubtedly due to the use of Rare Earth Elements (REE). They directly modify both physical and chemical properties in materials. An example of this is the progress in smart and high-resolution technologies, such as cell phones, computer hard drives, hybrid and electric vehicles, and LED monitors and lighting, as well as the attractive economic value that rare earth oxides possess in the world market. The Chilean Nuclear Energy Commission (CCHEN), together with the National Mining Company (ENAMI), began geological and metallurgical research. These studies allowed them to identify a prospect in the Atacama Region for studies that justify the technical and economic feasibility in the exploitation of a rare earth deposit as a new mining alternative. These previously conducted studies allowed to understand the fundamental parameters in the REE concentration for a Davidite ore. These studies reached a 60% recovery of REE at sulfuric concentration of 5M for temperatures between 90 to 100oC and a particle size less than 44 microns, with agitation being the only non-predominant parameter for this study. The purpose of this work is to increase the recovery of those elements that belong to the davidite ore, to obtain a leaching product with REE recoveries values greater than the previous studies, and reducing the concentration of the ions that affect negatively from post leaching processes. To validate this theory, the tests increased the leaching recovery of the impurity elements in the ore, especially iron, using two different methodologies. The first method incorporated NaCl into an H2SO4 leaching solution to increase the acid generation in the reaction, in order to enhance the dissolution of REE in leaching. This procedure showed that the increase in acid in the system over 2M and for NaCl concentration ranges between 0.5 to 1M, obtained recoveries over 60% REE. The second method included a reductive leaching in a H2SO4 leaching solution and the constant injection of sulphurous anhydride. This process dissolved the iron contained in the ore, and reduced it to its lower ionic state (ferrous ion). This addition allowed obtaining a recovery of 30% iron and fulfilling the purpose of the methodology, since the reaction potential in the system was over 600 mV, a range in which the ferrous ion is stable
[en] The occurrence, dispersion and concentration of U, Th with REE in favourable litho-structural geo-domains, are constrained by the geo-genetic nature of primary U and Th minerals in the host rock. The paper includes the use of a non-destructive analytical mineralogy technique, the Electron Probe Micro-analysis (EPMA), in complete in-situ minerlo-chemical analysis based geo-genetic finger printing of discrete primary U- and Th-minerals with REE, viz. uraninite, pitchblende, coffinite, brannerite, U-thorite, thorite and monazite (LREE + Th phosphate) that occurs in diverse rocks and along the coast of India respectively. (author)
[en] The mining industry is a vital contributor to national and global economies. It is a truly international business that depends on the trust and confidence of investors and other stakeholders for its financial and operational well-being. Unlike many other industries, it is based on depleting mineral assets, the knowledge of which is imperfect prior to the commencement of extraction. It is therefore essential that the industry communicates the risks associated with investment effectively and transparently in order to earn the level of trust necessary to underpin its activities. Enforceable mineral resource and mineral (Ore) reserves codes are critical to earning this confidence.
[en] A report has recently been made public which describes the findings of the International Uranium Resources Evaluation Project (IUREP) Mission to Madagascar. The IUREP Orientation Phase Mission to Madagascar estimates the Speculative Resources of that country to be within the wide range of 4 000 to 38 000 tonnes uranium. Such resources could lie in areas with known occurrences (uranothorianite, Ft. Dauphin up to 5 000 t U, i.e. 'pegmatoids'; uranocircite, Antsirabe up to 3 000 t U in Neogene sediments; carnotiteautonite, Karoo area up to 30 000 t U in sandstones and in areas with as yet untested environments (e.g. related to unconformities and calcretes). Modifications to existing uranium exploration programmes are suggested and policy alternatives reviewed. No specific budget is proposed. (author)