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Proceedings - European Metallurgical Conference, EMC 2015
Generically Dependent Continuant
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Synthesis and nature of the reaction of a solid solution of ammonium-potassium arsenojarosite in NaOH medium
A solid solution of ammonium-potassium arsenojarosite was synthesized for this study. It was chemically and mineralogically characterized by Inductively Coupled Plasma Spectrometry (ICP), elemental analysis, Atomic Absorption Spectrophotometry (AAS), X-Ray Diffraction (XRD) and Scanning Electron Microscopy with Energy-Dispersive X-Ray Spectroscopy (SEM-EDS). The following composition was obtained: 26.67 %25 Fe, 36.41 %25 SO4, 3.60 %25 K, 1 %25 NH4, 6.71 %25 AsO4 and 25.61 %25 OH–%2bH2O, which results in the following approximate formula: [(NH4)0.23K0.77] Fe2.47 [(SO4)1.69(AsO4)0.31] [(OH)4.1(H2O)1.9]. The amount of arsenic was higher than the reported by different authors who have synthesized similar compounds. The XRD results confirm that the obtained sample corresponds to ammonium-potassium arsenojarosite. The granulometric analysis showed that the main particle sizes are 38 and 25 µm, corresponding to mesh sizes 400 and 500. This indicates that a fine size particle was obtained. The compound’s nature of thereaction in NaOH was studied as well, showing an induction period characterized by the formation of active sites until a reaction front is established. It is followed by the progressive conversion period, in which K%2b, SO42- and NH4%2bincrease in the solution until reaching stabilization. The reaction was followed by determination of K with AAS. The obtained results are consistent with the kinetic model of constant-size spherical particles and unreacted core with chemical control. Partially decomposed particles were also observed by SEM, where an unreacted arsenojarosite core, a reaction front and an ash halo made of amorphous Fe(OH)3 with adsorbed AsO4 can be seen. © GDMB. All rights reserved.
Arsenojarosite; Characterization; Synthesis Absorption spectroscopy; Approximation algorithms; Atomic absorption spectrometry; Energy dispersive spectroscopy; Inductively coupled plasma; Iron compounds; Metallurgy; Particle size analysis; Potassium; Scanning electron microscopy; Sodium hydroxide; Synthesis (chemical); X ray diffraction; Approximate formulas; Arsenojarosite; Atomic absorption spectrophotometry; Chemical controls; Energy dispersive X ray spectroscopy; Granulometric analysis; Inductively coupled plasma spectrometry; Spherical particle; Solid solutions
A solid solution of ammonium-potassium arsenojarosite was synthesized for this study. It was chemically and mineralogically characterized by Inductively Coupled Plasma Spectrometry (ICP), elemental analysis, Atomic Absorption Spectrophotometry (AAS), X-Ray Diffraction (XRD) and Scanning Electron Microscopy with Energy-Dispersive X-Ray Spectroscopy (SEM-EDS). The following composition was obtained: 26.67 %25 Fe, 36.41 %25 SO4, 3.60 %25 K, 1 %25 NH4, 6.71 %25 AsO4 and 25.61 %25 OH– H2O, which results in the following approximate formula: [(NH4)0.23K0.77] Fe2.47 [(SO4)1.69(AsO4)0.31] [(OH)4.1(H2O)1.9]. The amount of arsenic was higher than the reported by different authors who have synthesized similar compounds. The XRD results confirm that the obtained sample corresponds to ammonium-potassium arsenojarosite. The granulometric analysis showed that the main particle sizes are 38 and 25 µm, corresponding to mesh sizes 400 and 500. This indicates that a fine size particle was obtained. The compound’s nature of thereaction in NaOH was studied as well, showing an induction period characterized by the formation of active sites until a reaction front is established. It is followed by the progressive conversion period, in which K , SO42- and NH4 increase in the solution until reaching stabilization. The reaction was followed by determination of K with AAS. The obtained results are consistent with the kinetic model of constant-size spherical particles and unreacted core with chemical control. Partially decomposed particles were also observed by SEM, where an unreacted arsenojarosite core, a reaction front and an ash halo made of amorphous Fe(OH)3 with adsorbed AsO4 can be seen. © GDMB. All rights reserved.