Project Results
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The project aimed to demonstrate by a detailed fundamental and applied investigationthetechnicallyfeasible
alternative for strategic metals production as Heavy and Rare Metals (HRM) consisting of Lanthanides and Gallium, Strontium, Rubidium, Yttrium and Wolfram by utilizing fresh and reuse landfilled fly ash and bottom ash as a source soft (pulverized) rock. Project RAREASH
Assessment of Possible Recycling Directions of Heavy & Rare Metals Discovered from Combustion Waste Products
The proposed approach, with a very limited experience in Europe and even worldwide, demonstrated innovative methods/technologies to develop metal recovery processes and transform wastes into high-grade andvaluable metals with various applications, creating the possibility for a fast and low-cost access to strategic metals and a widespread saving of EU primary mineral resources. The project achieved results will be used as an initial basis for the advanced, waste-less and environmentally safety utilization of various ashes to obtain concentrates, high purity reactives, metals and metallic salts, and adsorbents, metal and oxide nanoparticles, scale controlled and functionalized as well as solar collectors precursors potential manufacturing to be used in high-tech and environmental purposes. The characterization of Oltenia bottom ash, Polish coal ashes and LIPOR ashes was one of the main aims of the project together with the metals extraction. In this sense the characterization tasks were fully accomplishedand a much better insight on the characteristic of theses ashes towards their use as a secondary source of rare and heavy metals is an achievement of the project. Resuming: (i) it was found that Oltenia bottom ash is a potentially promising source of REY. However, Gdseems to be the most promising element, especially in the 0.090–0.125mm and < 0.063mm size fractions; (ii) it was found that for Polish samples the prospect for recovery are four elements (cerium, lanthanum, scandium, neodymium), which account for a total of 77% of the total rare earth elements contained in the examined waste. Coefficients of variation of these elements are in the range of 6% to 11%. The average content of such rare earth elements as scandium, lanthanum, cerium, praseodymium, neodymium, and dysprosium is higher than in the earth's crust. (iii) in LIPOR fly ash between 75% and 85% of the samples mass is concentrated in the >75 μm size fractions, and the <25 μm fraction is always less than 2%. The insoluble residue corresponds to approximately a 20%ofthe fly ash and does not vary with time. The chemical analysis of this fraction shows that its major compounds are chlorides, sulfates and CaO. However, Pb value was also high (783 ppm).
The LIPOR bottom ash size fraction < 2mm shows high concentration of Mo, Cu, Pb, Zn, Cd, Sb, In, Zr, and Sn in relation to the Upper Continental Crust, whereas the fly ash shows high concentrations of Mo, Cu, Pb, Zn, Cd, Sb, W, In, Bi, Zr, Sn, and Se in relation to the Upper Continental Crust. Meanwhile, major, minor and trace elements do not present high variations with time. Derivative scientific objectives: The Oltenia bottom ash not used for metals extraction has a promising potential to be recycled in making ceramic composites. It was found that in coal fly ash and bottom ash from Romania and Poland, several morphotypes did not fit into the general fly ash classifications, unless grouped together as “undifferentiated inorganics”. However,many of these morphotypes not only have distinctive petrographic patterns but are also characterized by a chemical assemblage dominated by Ca, Mg, and P. Therefore, the following nomenclature are proposed: “calcispheres”,
“calcimagnesiaspheres” and “magnesiaspheres”.
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