Elemental recoveries are compared to the certified values results indicate generally good to excellent recoveries across a range of alkaline earth, rare earth, transition metal, and actinide elements. Finally, the sample decomposition method is performed on several soil and pitchblende ore standard reference materials, after which elemental constituent analysis is performed by ICP-OES and ICP-MS. The degree of solubilization of these sample classes are compared to the fluoride stoichiometry that is theoretically necessary to enact complete fluorination of the sample types. Method performance is evaluated across two variables: duration of molten ABF treatment and ABF reagent mass to sample mass ratio. Herein, a sample decomposition method that employs molten ABF sample treatment in the initial step is systematically evaluated across a range of inorganic sample types: glass, quartz, zircon, soil, and pitchblende ore. It has been more recently applied to the decomposition of inorganic matrices prior to elemental analysis. HF) is a well-known reagent for converting metal oxides to fluorides and for its applications in breaking down minerals and ores in order to extract useful components.Thus, this work provides a novel strategy for the high-value utilization of HAFA.Īmmonium bifluoride (ABF, NH4F Subsequently, dissolution of ammonium fluosilicate with a surfactant produced silica nanoparticles with a surface area of 454.2 m²/g and a recyclable ammonium fluoride solution through an ammonification process. However, impurities in HAFA inhibited further improvement of the Al/Si ratio. Silica in HAFA was transformed into gaseous ammonium fluosilicate, which was separated from the calcined product by condensation, thereby increasing the Al/Si ratio. The results showed that the Al/Si ratio reached 8.83 when HAFA with a F/Si ratio of 5.0 was calcined at 850 ☌ for 60 min. The influence of the ammonium fluoride to silica in HAFA molar ratio (F/Si), the calcination temperature, and calcination time on the alumina to silica mass ratio (Al/Si) of the calcined product were investigated. In this study, a novel method of alumina enrichment by ammonium fluoride activation was proposed. Thus, alumina enrichment via the separation of silica is a key technique for HAFA utilization. However, this industrial application has been restricted by the high silica content of HAFA. Įxtraction of alumina from high-alumina fly ash (HAFA) enhances the value-added utilization of HAFA. Overall, this study proved that NH 4 HF 2 is one of the fluorination agents that is capable of synthesizing ThF 4. In addition, the heating of ammonium thorium fluoride at 450 ☌ was sufficient to produce ThF 4. The optimum molar ratio in synthesizing ammonium thorium fluoride was 1.0:5.5 (ThO 2 :NH 4 HF 2 ) with 5 days reaction time. In this study, ammonium thorium fluoride was synthesized through the fluorination of ThO 2 at room temperature. The characterization of ThF 4 was established using X-ray diffraction (XRD) and scanning electron microscopy–dispersion X-ray spectroscopy (SEM–EDX). Next, the mixtures were analyzed using X-ray diffraction (XRD) at the intervals of 5, 10, 15, and 20 days, followed by the heating of the mixtures at 450–750 ☌ with argon gas flow. Fluorination was performed at room temperature by mixing ThO 2 and NH 4 HF 2 at different molar ratios, which was then left to react for 20 days. The present study aims to investigate the fluorination of thorium oxide (ThO 2 ) by ammonium hydrogen difluoride (NH 4 HF 2 ). Quantum‐chemical calculations show that the M–F bonding interactions in 4– anions (M = Th – Bk) are strongly ionic. A molecular, mononuclear 4– anion is present in the compound (NH4)4 which was synthesized from NpO2 by treatment with hydrofluoric acid and subsequently with aqueous NH4F solution. Quantum‐chemical calculations of 4– anions show that the M–F bonds are highly ionic and the energy differences between different ligand arrangements likely can be overcome by lattice energies of different crystal structures in the solid state. In (NH4)4, molecular 4– anions, which can either be described as a distorted square‐antiprism or a bicapped trigonal prism, are present which are bound to the NH4+ ions via N–H The crystal structure of the compound was determined by single‐crystal X‐ray diffraction and observed to be isotypic to the uranium analogue. Olive‐green single crystals of ammonium octafluoridoneptunate(IV), (NH4)4, were obtained by converting NpO2 to a green neptunium tetrafluoride hydrate with hydrofluoric acid and subsequent treatment of the fluoride with an aqueous NH4F solution.
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